BIO 220 Chapters 18, 19, 20
Can cause pneumonia, especially in compromised patients, produces red pigmented colonies in culture
Serratia marcescens
figure 19.4
myonecrosis
figure 19.8
neonatal tetanus
separation of clinically important species of Staphylococcus
table of tests
NONCOLIFORM LACTOSE-NEGATIVE ENTERICS
***PROTEUS, MORGANELLA, AND PROVIDENCIA*** Where are these organisms normally found? - polluted water - associated with human and animals What types of infections do they cause? - UTI, wound infections, pneumonia *note: - Proteus vulgaris is motile so it tends to swarm an agar plates - figure 20.17 picture of wavelike, swarming pattern - let's swarm, weeee, you smell funny ***SALMONELLA AND SHIGELLA*** What is unique about these organisms? - primary pathogens, not normal human flora Salmonella typhi: What disease does this organism cause? - typhoid fever How does one get this disease? - fecally contaminated food or water How does this organism cause disease? - invasive diarrhea that leads to septicemia (most are from cases from people traveling to developing country) Salmonella cholera-suis: What is the source of this organism? - pigs (swine) Salmonella enteritidis: What kind of disease does this organism cause? - the one we hear most about - salmonella food poisoning and gastroenteritis Where do infections from this organism originate? - cattle, poultry, rodents, reptiles, animal, and dairy products - heavily associated with chicken so new guidelines is you don't wash raw chicken because it spreads it to other parts of the kitchen - fomites contaminated with animal intestinal (fecal) flora - raw eggs ***SHIGELLA*** What kind of disease does this genus of organisms cause? - shigellosis: incapacitating dysentery How do these organisms cause disease? - invades villus of large intestine *note - S. dysenteriae, S. sonnei, S. flexneri, and S. boydii (some are associated with our area of the world; some are carried abroad) - toxin producers and can be very serous - Shigella outbreaks can happen in daycares (lab 35) ***ENTERIC YERSINIA PATHOGENS*** Name 2 species in this group and the diseases they cause: - Yersinia enterocolitica: inflammation of the ileum; food borne illness often associated with pork products (lab 35) - Yersinia pseudotuberculosis: infection similar to tuberculosis ***NONENTERIC YERSINIA PESTIS AND PLAGUE*** - is of most interest because it is Yersinia pestis that causes the plague How do humans come in contact with this organism? - contact with animals or other infected humans What serves as a vector for this disease? - fleas What 3 types of plaque can develop? - humans are an accidental host in this process - ring around the rosie 1. Bubonic: infects lymph nodes in groin or axilla causing them to swell (bubo) 2. Septicemic: subcutaneous hemorrhage causing the skin to turn black (black plague) 3. Pneumonic: lungs are infected; highly contagious; fatal without treatment
Which organisms are primary pathogens? Click all that apply.
- Salmonella - Shigella
figure 19.14
- diagnosing diphtheria - characteristic pseudomembrane in throat
Describe some microscopic characteristics of staphylocci:
- gram-positive - cocci - arranged in clusters - Spherical cells arranged in irregular clusters •
figure 20.3
- picture of Pseudomonas (left) and Staphylococcus (right) - Pseudomonas produces a blue to green pigment and is very drug resistant
figure 19.27
- picture of man with N. brasiliensis - This case of pulmonary disease has extended through the chest wall and ribs to cutaneous surface
Describe the growth/physiological characteristics of staphylococci:
- they like body temperature (37 degrees C) - facultative anaerobe - since they grow on the skin they can stand a lot of extremes: high salt (sweat), extremes in pH (could be due to sweat), and fluctuating temperatures (including high temperatres) •Grows in large, round, opaque colonies •Optimum temperature of 37oC •Facultative anaerobe •Withstands high salt, extremes in pH, and high temperatures •Produces many virulence factors
Has cutaneous (skin), pulmonary (lung), and gastrointestinal forms, treated with Cipro antibiotic, complex vaccination only for military personnel. Cutaneous form causes black eschar lesion, spores are formed centrally in these cells.
Bacillus anthracis
Name the 5 most important staphylococcal human pathogens:
1. Staphylococcus aureus - top one The rest typically produce milder opportunistic diseases 2. Staphylococcus epidermidis 3. Staphylococcus hominis 4.Staphylococcus capitis 5. Staphylococcus saprophyticus
Airborne, attaches to dust particles, everywhere, can cause diarrheal disease, no treatment, short-lived (24 hours); a good reason to keep foods covered and another reason to keep foods at the proper temperature (hot food hot, cold foods cold).
Bacillys cereus
Causes "Whooping Cough" (patients make characteristic "whoop" sound), covered by the DTaP (or similar) vaccine, biggest threat is to babies who are too young to have their full set of vaccinations and can suffocate from this disease
Bordetella pertussis
Aerobic Gram-Negative Nonenteric Bacilli
Aerobic Gram-Negative Nonenteric Bacilli - large, diverse group of non-spore-forming bacteria - wide range of habitats: large intestines (enteric), zoonotic, respiratory, soil, water - most are not medically important; some are true pathogens, some are opportunists - all have a lipopolysaccharide outer membrane of cell wall (endotoxin) Pseudomonas - Pseudomonas aeruginosa Brucella - Brucella abortus - Brucella suis Francisella - Francisella tularensis Bordetella - Bordetella pertussis - Alcaligenes faecalis Legionella - Legionella pneumophila
BACILLUS
BACILLUS - Bacillus anthracis - Bacillus cereus Describe the microscopic appearance of Bacillus: - gram positive - spore-forming - motile rods. Describe the growth/physiological characteristics of Bacillus: - aerobic, - catalase positive - versatile What is the primary habitat of Bacillus? - soil
Bordetella
Bordetella pertussis: What disease does Bordetella pertussis cause? - pertussis or whooping cough (because of they type of cough - several coughs followed by a sharp inhalation of air) What are key characteristics of this disease? - type of cough - causes a series of several coughs followed by a sharp inhalation of air ("whoop") What effect does this disease have on the respiratory system? - loss of ciliary mechanism leads to buildup of mucus and blockage of the airways (especially true of babies and young children - could suffocate) How is this disease prevented? - vaccine - DTaP - acellular vaccine contains toxoid and other Ags ("P" of the vaccine) Alcaligenes faecalis: What types of infections is Alcaligenes faecalis associated with? - opportunistic infections
BRANHAMELLA and MORAXELLA
Briefly describe Branhamells catarrhalis: - found in nasopharynx - significant opportunist organism seen in in cancer, diabetes, alcoholism Briefly describe Moraxella: -Bacilli - found on mucous membranes - can cause opportunistic infections as well
causes undulant fever, a.k.a. Bang disease, produces undulating fever pattern that can last a year
Brucella
CATALASE TEST Staph and strep can cause similar types of infections. They can both cause skin types of "things". COAGULASE TEST When a patient has a staph infection, we want to know if it is Staphylococcus aureus (which is more invasive and has resistance problems) or if it is another type of Staphylococcus instead (which is generally less serious). We can do the coagulase test to figure this out
CATALASE TEST - Staphylococci are catalase positive (mixed with hydrogen peroxide and it produces bubbles) - Streptococci are catalase negative (won't produce any bubbles for lack of that enzyme COAGULASE TEST - Staphylococcus aureus is coagulase positive --> it coagulates (clots) blood --> it will clot the blood when you mix it with plasma - other staphylococci species are coagulase negative
CHAPTER 18 - QUIZ
CHAPTER 18 - QUIZ
CHAPTER 19 - QUIZ
CHAPTER 19 - QUIZ
CHAPTER 20 - QUIZ
CHAPTER 20 - QUIZ
CLOSTRIDIUM
CLOSTRIDIUM - Clostridium perfringes - Clostridium difficile - Clostridium tetani - Clostridium botulinum Describe the microscopic appearance of Clostridium: - Gram positive - spore-forming - rods Describe the growth/physiological characteristics of Clostridium: - anaerobic - catalase negative picture of - Clostridium perfringes (top) - Clostridium tetani (bottom) - Clostridium has terminal or sub-terminal endospores
Anaerobic, spore-former, can cause gas gangrene (separates muscles tissues, causing death of the tissue), not very invasive - has to be deep in a wound for anaerobic conditions, treatment - clean wounds, hyperbaric oxygen therapy, penicillin or cephalosporin. Can also cause mild intestinal illness, second most common cause of food poisoning worldwide, spores are formed terminally (at the end of) these cells.
Clostridium perfringes
Anaerobic, spore-former, found in the soil, causes lockjaw, covered by DTaP vaccine - booster needed every 10 years, toxin causes muscles to contract (can be fatal), most common in neonates in developing countries, geriatric patients, and IV drug users, requires a wound for anaerobic conditions, treated with antitoxin, penicillin, muscle relaxers, spores are formed terminally (at the end of) these cells and cause the spore-forming cells to appear club-shaped (like a caveman club).
Clostridium tetani
Describe where the following staphylococci reside as normal flora and what infections they cause:
Coagulase-negative staphylococcus; frequently involved in nosocomial and opportunistic infections: • S. epidermidis - lives on skin and mucous membranes; endocarditis, bacteremia, UTI • S. hominis - lives around apocrine sweat glands • S. capitis - live on scalp, face, external ear (head) •All 3 of the above may cause wound infections (and some other things) by penetrating through broken skin • S. saprophyticus - infrequently lives on skin, intestine, vagina; UTI (associated with UTI in a very specific population - females age 16-25 and sexually active
Anaerobic, spore-former, causes gastroenteritis, produces a toxin, which causes muscles to relax (can be fatal), can cause canned foods to expand outward due to gas produced, can especially be found in inadequately preserved home canned foods, presence of spores in honey can cause infant form of the disease - reason why honey has warning that it is not to be given to children under 1 year of age because their immune systems can't handle a few spores until after 1 year of age.
Clostridium botulinum
Causes antibiotic-associated colitis, treatment - replace fluids and stop broad-spectrum antibiotics causing the problem (present in low numbers in the colon already and broad-spectrum antibiotics cause it to overgrow, resulting in infection), major cause of diarrhea in hospitals.
Clostridium difficile
Where do staphylococci reside in/on the human body?
Common inhabitant of the skin and mucous membranes
Produces an A-B type of toxin, causes a pseudomembrane to form on the back of the throat (sometimes has to be removed surgically to prevent closing of the airway).
Corynebacterium diptheriae
Describe some microscopic characteristics of streptococci: Describe the growth/physiological characteristics of streptococci:
Describe some microscopic characteristics of streptococci: • Gram-positive spherical/ovoid cocci arranged in long chains; commonly in pairs • Non-spore-forming, nonmotile • Can form capsules and slime layers Describe the growth/physiological characteristics of streptococci: • Facultative anaerobes • Do not form catalase (i.e. catalase negative), but have a peroxidase system (which is a similar system to catalase) • Most parasitic forms are fastidious and require enriched media (they are fastidious so you have to grow them on blood agar which is enriched) • Small, nonpigmented colonies • Sensitive to drying, heat, and disinfectants * picture is of strep in chains (streptococcus)
Listeria monocytogenes:
Describe the microscopic appearance of Listeria: - gram-positive - non-spore-forming - ranging from coccobacilli (between cocci and baccili) to long filaments What is its virulence attributed to? - unique because of its ability to replicate in the cytoplasm of cells after inducing phagocytosis (after it has been ingested so it avoids humoral immune system) Where is it found? - primary reservoir is soil and water; animal intestines What disease does it cause? - Listeriosis What products is it associated with? - most cases associated with dairy products (Blue Bell ice cream), poultry, and meat (occasionally produce) How serious is this disease? - usually not very serious - often mild or subclinical in normal adults - immunocompromised patients, fetuses (miscarriage), and neonates; affects brain and meninges - 20% death rate How is it detected? - rapid diagnostic tests using ELISA, immunofluorescence, and DNA analysis How is it treated and prevented? - ampicillin and Bactrim (trimethoprim/ sulfamethoxazole ) - prevention - pasteurization and cooking figure 19.10 picture - multiplication cycle of Listeria monocytogenes - Listeria induced their own phagocytosis, multiply in the cytoplasm of the host cell, and then invade other cells
Mycobacterium tuberculosis:
Describe the microscopic appearance of Mycobacterium tuberculosis: - tubercle bacillus - forms cords or thread like cells What virulence factors does this organism have? - complex waxes - cord factor that causes it to grow this way What disease does it cause? - tuberculosis (TB) What are predisposing factors for this disease? - inadequate/poor nutrition - debilitated immune system - lack of access to good medical care - lung damage - genetics How common is carriage of this organism worldwide? - one third (1/3rd) of the world population What is the recent rise in the number of cases of this disease in the U.S. being attributed to? - immigrants/immigration because it is more common in the rest of the world How is this disease transmitted? - transmitted by airborne respiratory droplets (you need to mask up for TB patients) What percentage of infected people develop a clinical case of this disease? - 5% to 10% of infected people develop clinical disease Why is this? - this is because the disease progresses slowly How long might TB be latent? - years How can this disease progress? - if the tubercules that are formed in the lungs break open and release the cells into he circulation in the rest of the body What 4 ways is this disease diagnosed? 1. Mantoux skin test - local intradermal injection of purified protein derivative (PPD); look for red wheal to form in 48-72 hours - induration; established guidelines to indicate interpretation of result based on size of wheal and specific population factors - if this is positive an x-ray is done; some people will be positive even with saline 2. chest x-rays - looks for TB formations in the lunds; this x-ray could also indicate pneumona, lung cancer 3. acid-fast stain of a sputum collection (acid-fast bacilli in specimen) 4. culture (cultural isolation and biochemical testing) will be done for confirmation, but it takes 4 weeks to grow * note: preliminary treatment will be done based on 2 or 3 of these being positive How is this disease treated and prevented? - long term - 6 months to 2 years with a 2 drug combination - vaccine: other parts of the world have a vaccine figure 19.19 - picture of TB in the lungs - x-ray of secondary tubercular infection - the body will attempt to wall it off and form scar tissue around it; if the disease progresses it can break out of this and get into the circulation and travel around the body
Describe what members of the genus Neisseria look like microscopically: Describe the growth and physiological characteristics of these organisms: Where do they reside naturally? Name the 3 genera in this family: Name the 2 primary human pathogens in this family:
Describe what members of the genus Neisseria look like microscopically: - Gram-negative cocci - often diplococci (2 connected) - Genus Neisseria: gram-negative, bean-shaped, diplococci Describe the growth and physiological characteristics of these organisms: • Gram-negative, bean-shaped, diplococci • None develop flagella or spores • Capsules on pathogens • Pili • Strict parasites, do not survive long outside of the host • Aerobic or microaerophilic • Oxidative metabolism • Produce catalase (catalase positive) and cytochrome oxidase (oxidase positive) • Pathogenic species require enriched complex media (chocolate agar ) and higher levels of CO2 (carbon dioxide) Where do they reside naturally? - Residents of mucous membranes of warm-blooded animals (including humans) Name the 3 genera in this family: - Neisseria (we will talk mainly about this genera) - Branhamella - Moraxella Name the 2 primary human pathogens in this family (genus Neisseria): - Neisseria gonorrhoeae - Neisseria meningitidis
Causes 70% of traveler's diarrhea, 50-80% of UTI's (often treated with Cipro or Bactrim antibiotic), has pathogenic and hemorrhagic strains, ex. 0157:H7, that produces a toxin
E. coli
Enterobacteriaceae Family - E. coli - Klebsiella pneumoniae - Ebterobacter - Citrobacter - Serratia marcescens
E. coli: E. coli is known for being the most: - most common aerobic and non-fastidious bacterium in gut - it is facultative but capable of aerobic growth Name the 4 pathogenic strains of E. coli and describe the diseases they cause: 1. Enterotoxigenic E. coli causes severe diarrhea due to heat-labile toxin and heat-stable toxin - stimulate secretion and fluid loss; also has fimbriae (not the only one that produces a toxin) 2. Enteroinvasive E. coli causes inflammatory disease of the large intestine 3. Enteropathogenic E. coli linked to wasting form infantile diarrhea 4. Enterohemorrhagic E. coli, O157:H7 strain, causes hemorrhagic syndrome (intestines bleed) and kidney damage * these virulent strains all of these can be easily fatal which are different from the normal E. coli that we have in our large intestinges E. coli accounts for what percentage of the cases of traveler's diarrhea? - 70% E. coli accounts for what percentage of UTI's? - 50-80% (so much so that we treat UTI's as presumptive for E. coli unless other indications) E. coli is a common contaminator of: - water (absence of coliforms is what we want in drinking water report) figure 20.14 - picture of rapid identification of E. coli O157:H7 (lab 35) Klebsiella pneumoniae: Where does this organism normally reside? - respiratory tract What types of disease does Klebsiella pneumonia cause? - pneumonia (lab 23- currant jelly sputum) Enterobacter: What types of disease does Enterobacter sp. cause? - UTI Citrobacter: What types of disease does Citrobacter sp. cause? - UTI Serratia marcescens: What types of disease does Serratia marcescens cause? - atypical pneumonia What makes colonies of this organism easily identifiable? - produces a red pigment and can be seen if cultures are grown at room temperature (but usually don't show if grown a body temp 37 degrees in an incubator) *note: any of these coliform organisms can be displaced and cause UTI
Enterobacteriaceae Family
Enterobacteriaceae Family - E. coli - Klebsiella pneumoniae - Ebterobacter - Citrobacter - Serratia marcescens What symptom does this family of organisms cause? - diarrhea Enterics, along with Pseudomonas species, cause almost 50% of what types of infections? - nosocomial infections (hospital acquired) What key characteristics do genera in this family share? (lab 14 enterotube) - all ferment glucose - oxidase negative - catalase positive (See Figure 20.10 (7th ed.) Outline of biochemical traits for separating selected enteric genera) - shows different lab tests (enterotube for example) What antigenic structures/virulence factors do members of this family have? - figure 20.13: picture of antigenic structures in gram-negative enteric rods - H antigen: associated with their flagella (H stands for German word for hair because they are very hairlike) - K antigen: K is for capsule (in German capsule is spelled with a K) - O antigen: somatic anitgen or the body of the cell or cell wall antigen; may be called outer core - endotoxins - exotoxins
Escherichia coli, Klebsiella pneumonia, Enterobacter, Citrobacter, Serratia marcescens - cause diarrheal diseases and UTIs due to close proximity to the urinary tract
Enterobacteriaceae family
figure 19.18
Figure 19.18 - picture of skin testing for tuberculosis: the Mantoux test
causes "Rabbit fever," from the bite of wild animals
Francisella tularensis
picture of Figure 18.17 Diagnosing Streptococcus pneumoniae
Gram stain of sputum from a pneumonia patient
What virulence factors are members of the Enterobacteriaceae family known for?
H, K, O antigens, exotoxin, endotoxin
Causes pinkeye
Haemophilus aegyptius
causes acute bacterial meningitis in young children (2 month to 5-year-olds, prevented by vaccination, can be identified by the XV test or serotyping; the type b is the one of most concern; named because it can be a secondary bacterial infection following a common viral infection (that we also vaccinate for)
Haemophilus influenzae
IRREGULARLY-SHAPED NONSPOREFORMERS
IRREGULARLY-SHAPED NONSPOREFORMERS - Corynebacterium diphtheriae: - Propionibacterium acnes: What is the term for irregularly shaped and how do they stain? - pleomorphic (because they can morph into different shapes) - they stain unevenly for this reason What are some unique characteristics of this group? - possess mycolic acids an a unique type of peptidoglycan in their cell wall
Describe the following types of Staphylococcus infections:
LOCALIZED INFECTIONS 1) Abscess - Local infection that is an inflamed, fibrous lesion enclosing a core of pus 2) Folliculitis - superficial inflammation of hair follicle; usually resolved with no complications but can progress 3) Furuncle - boil; inflammation of hair follicle or sebaceous gland progresses into abscess or pustule (very common) 4) Carbuncle - larger and deeper lesion created by aggregation and interconnection of a cluster of furuncles 5) Impetigo - bubble-like swellings that can break and peel away, may be crusty - most common in newborns - can be cause by staph or strep SYSTEMIC INFECTIONS 6) Osteomyelitis - infection is established in the metaphysis (wider portion of the long bone); abscess forms - infection of the bone - it can actually break the bone -) Bacteremia - primary origin is bacteria from another infected site or medical devices; endocarditis (inflammation of the lining of the heart chambers or valves) possible - you can have bacteremia or septecemia with any organism 7) Food intoxication - ingestion of heat stable enterotoxins - gastrointestinal distress - this is where you ingest the organism and it produces the enterotoxins which cause gastrointestinal distress 8) Toxic shock syndrome - produces the toxic shock syndrome toxin - toxemia leading to shock and organ failure which is very serious 9) Staphylococcal scalded skin syndrome - SSSS - this is where it produces the exfoliative toxin - toxin induces bright red flush, blisters, then desquamation (peel) of the epidermis because the layers of the skin separate as if it has been scalded - we see this in young children, babies, infants
Causes a respiratory disease from standing water (ex. ponds or stagnant air conditioning water) that has a 30% fatality rate and was first diagnosed in the 1970s when there was an outbreak at a convention at a hotel.
Legionella pneumophila
Causes a disease associated with contaminated dairy products, poultry, meat, and sometimes produce, can cause miscarriage in pregnant women, prevented by pasteurization and proper cooking, virulence factor = they induce their own phagocytosis and multiply in phagocytes instead of being digested there.
Listeria monocytogenes
What is MRSA and why is it of concern?
MRSA: methicillin-resistant Staph aureus - carry multiple resistance - some strains have resistance to all major drug groups except vancomycin - vancomycin is toxic for a normal healthy patient otherwise the toxicity probably wont be a problem --> can be a problem for older or health compromised patients - organisms that are resistant to one antibiotic can typically carry resistance to multiple antibiotics - we now have VRSA which means we have to antibiotic treatment left for that patient so the organism can overcome the patient or the patients immune system may defeat the organism ultimately
MYCOBACTERIA
MYCOBACTERIA - Mycobacterium tuberculosis - Mycobacterium leprae Describe the microscopic appearance of Mycobacteria: - Gram-positive irregular bacilli Describe the growth/physiological characteristics of Mycobacteria: - produce catalase (catalase positive) - possess mycolic acids and a unique type of peptidoglycan -do not form capsules, flagella, or spores - unique because grow very slowly (these take weeks or longer to grow so can't do a 24 hour culture) What staining technique do we use to identify Mycobacteria and what do they stain? - acid-fast staining (mycobacteria are stained with a primary stain that is pink, then washed with acid, then a secondary blue stain is used; mycobacteria are acid-fast positive because they hold fast to that primary pink stain even after being washed with the acid) figure 19.15 - acid-fast stain: mycobacteria are acid-fast positive
Has lepromatous and tuberculoid forms, is endemic worldwide and still occurs today, though we don't isolate patients as we did in years past.
Mycobacterium leprae
Symptoms include malaise, fever, chills, productive cough, weight loss, confirmed by acid-fast positive stain, positive Mantoux skin test, chest x-ray showing the presence of this organism, growth on specific media, virulence factors - complex waxes, mycolic acids, cord factor, 6-24 month combined therapy, 1/3 of world population carries it, transmitted by respiratory route, 60% fatality rate if untreated in disseminated stage.
Mycobacterium tuberculosis
NEISSERIACEAE
NEISSERIACEAE
Causes gonorrhea, the "gonococcus," very fastidious- grow on chocolate agar, asymptomatic 10% of the time in males and 50% of the time in females, causes discharge in both, causes inflammation/blindness in newborns, so all newborns are given ointment in the eyes upon birth to prevent infection just in case.
Neisseria gonorrhoeae
Causes epidemic meningitis (prevalent cause of meningitis), the "meningococcus," very fastidious - grow on chocolate agar, children and young adults are at highest risk, vaccine available, can be deadly if untreated, hallmark symptom is a stiff neck, treated with penicillin, close contacts of infected person treated prophylactically.
Neisseria meningitidis
OXIDASE-POSITIVE NONENTERIC PATHOGENS
OXIDASE-POSITIVE NONENTERIC PATHOGENS - Pasteurella multocida - Haemophilus influenzae - H. aegyptius - H. ducreyi - H. parainfluenzae - H. aphrophilus PASTEURELLA - Pasteurella multocidia: zoonotic, opportunistic organism that causes a local infection that can spread after a person has been scratched or bitten by an animal HAEMOPHILUS How fastidious are these organisms? - very fastidious; must be grown on chocolate agar (lab 24) Name 5 species of Haemophilus and characteristics of each: 1. Haemophilus influenzae: - main one we are interested in and mainly strain B - causes acute bacterial meningitis particularly in 2months - 5 year olds - Hib vaccine - called influenzae not because it is the flu but because it can cause a secondary bacterial infection after the influenza virus has caused an infection 2. Haemophilus aegyptius: - very contageous - causes conjunctivitis (pink eye); school children who have this can't return until it clears up 3. Haemophilus ducreyi - chancroid STD 4. Haemophilus parainfluenzae - can exist as normal flora but can cause endocarditis 5. Haemophilus aphrophilus - can exist as normal flora but can cause endocarditis
According to the test (p. 543 of the 7th ed., first paragraph, last sentence), where does the burden of effective deterrence of Staphylococcus infections fall?
Prevention of Staphylococcal Infections •Universal precautions by healthcare providers to prevent nosocomial infections •Hygiene and cleansing •According to the text: "The burden of effective deterrence again falls to meticulous handwashing, proper disposal of infectious dressings and discharges, isolation of people with open lesions, and attention to indwelling catheters and needles.
Produces blue-green pigment and grape-like odor in culture and in wound infections
Pseudomonas aeruginosa
REGULARLY-SHAPED NONSPOREFORMERS
REGULARLY-SHAPED NONSPOREFORMERS - Listeria monocytogenes - Erysipelothrix rhuisopathiae
Describe the following types of Streptococcus pyogenes infections:
SKIN INFECTIONS • Impetigo (pyoderma) - superficial lesions that are bubbly and crusty and can peel and break and form highly contagious crust; often occurs in epidemics in school children; also associated with insect bites, poor hygiene, and crowded living conditions • Erysipelas - pathogen enters through a break in the skin and eventually spreads to the dermis and subcutaneous tissues; can remain superficial or become systemic; causes redness and swelling THROAT INFECTIONS • Streptococcal pharyngitis - strep throat; produces characteristic white spots on the tonsils; you can get strep throat if you don't have tonsils but it's more common to occur if you do SYSTEMIC INFETIONS • Scarlet fever - strain of S. pyogenes carrying a prophage that codes for erythrogenic toxin; can lead to sequelae (pathologic condition resulting from a disease); produces erythrogenic toxin; often occurs from untreated strep throat or reoccurring strep throat infections • Streptococcal toxic shock syndrome (Streptococcal TSS) - when you have large numbers of the organism they can put out the same sort of toxins produced by the staphs that causes shock and organ failure • Necrotizing Fasciitis - also known as flesh eating disease; certain strains of Strep. pyogenes or Staph. aureus can do this; may have to amputate to get out ahead of the organism • Rheumatic fever - follows overt or subclinical pharyngitis in children; carditis with extensive valve damage possible, arthritis, chorea (abnormal involuntary movement disorder), fever; affects the joints and can affect the heart; can also come from untreated strep throat or reoccurring strep throat infections • Acute glomerulonephritis - nephritis (inflammation of the nephrons in the kidneys), increased blood pressure, occasionally heart failure; can become chronic leading to kidney failure; can be combined with some of the other systemic infections
STAPHYLOCOCCI
STAPHYLOCOCCI
STREPTOCOCCI
STREPTOCOCCI
Describe where the following streptococci reside as normal flora and what infections they cause:
STREPTOCOCCI S. PYOGENES Lancefield Group: A Where it resides in/on the human body: human throat What type(s) of infection it causes: skin, throat infections (strep throat - streptococcal pharangitis), scarlet fever, rheumatic fever S. AGALACTIAE Lancefield Group: B Where it resides in/on the human body: human vagina, cow udder What type(s) of infection it causes: meningitis in newborns (neonatal) (this is why we test pregnant women and they get antibiotics if positive, wound infections VIRIDANS STREPTOCOCCI Lancefield Group: various Where it resides in/on the human body: human oral cavity What type(s) of infection it causes: usually don't cause a lot of trouble, maybe cavities, endocarditis in heart patients S. PNEUMONIAE Lancefield Group: not in a goup Where it resides in/on the human body: human respiratory tract (RT) What type(s) of infection it causes: bacterial pneumonia ENTEROCOCCUS FAECALIS (formerly Streptococcus faecalis) Lancefield Group: D Where it resides in/on the human body: human and animal intestine What type(s) of infection it causes: most commonly associated with UTI, endocarditis
Primary/true pathogen, source is animals including reptiles, or fomites, causes gastroenteritis
Salmonella enteritidis
Primary/true pathogen, causes typhoid fever, source is fecally-contaminated food or water, causes invasive diarrhea that can lead to septicemia
Salmonella typhi
Primary/true pathogen, causes dysentery, most often found circulating through daycare centers
Shigella
Which of the following organisms are beta-hemolytic? Click all that apply.
Staphyloccocus aureus Streptococcus pyogenes Streptococcus agalactiae
Causes skin infections: furuncles (boils), carbuncles, impetigo, scalded skin syndrome, toxic shock syndrome, has the most virulence factors of any pathogen, found on the skin and mucous membranes, can therefore withstand high salt conditions, and temperature and pH fluctuations, catalase positive, coagulase positive, beta-hemolytic, MRSA - difficult to treat, have to use vancomycin, some isolates are even VRSA.
Staphylococcus aureus
What is significant about the number of virulence factors that Staphylococcus aureus has?
Staphylococcus aureus produces many virulence factors - more than any other pathogen
Describe the 10 virulence factors of Staphylococcus aureus below:
Staphylococcus aureus produces many virulence factors - more than any other pathogen - these factors can be present in other organisms as well ENZYMES 1) Coagulase - coagulates plasma and blood; produced by 97% of human isolates; diagnostic; if the immune system is trying to get to this organism to kill it, the organism can put out the coagulase enzyme to keep the WBC away 2) Hyaluronidase - digests connective tissue - this organism can be a flesh eater that eats deeper into the body because of its ability to digest connective tissue 3) Staphylokinase - digests blood clots - if the immune system is trying to wall it off (block it) from going deeper into the body by clotting, then the organism can eat through those blood clots using this enzyme 4) Lipases - digest oils; enhances colonization on skin - oil on the skin is inhibitory for lots of organisms, but Staphs can withstand that due to the presence of these lipases 5) Penicillinase - inactivates penicillin so penicillin would not be an effective antibiotic to use against Staphylococcus aureus • DNase (not in top 5 list) - digests DNA TOXINS 6) Hemolysins (α, β, γ, δ) - β is the worst because it can lyse red blood cells -> β completely lyses the RBC so that it clears out the blood - different strains produce other hemolysins as well 7) Leukocidin - kills WBC - lyses (kills) neutrophils and macrophages (n & m are both WBC of the 2nd line of defense of the immune system) 8) Enterotoxin - induce gastrointestinal distress: diarrhea, vomiting, nausea, cramping, those types of things 9) Exfoliative toxin - can produce an exfoliative toxin that exfoliates the skin or causes it to peel - separates the epidermis from the dermis 10) Toxic shock syndrome toxin (TSST) - can produce TSST if an organism is in large numbers in an area - this toxin is particularly associated with the use of tampons or contraceptive sponges that are left in too long because you are trapping these organisms in an area and if you trap them for too long they will increase in number (multiply) and grow too large in numbers that put out this toxin - induces fever, vomiting, shock, systemic organ damage - can be deadly
In Group B - pregnant women are tested for carriage of this organism due to the risk of infection to newborns (meningitis), detect by positive CAMP test, fastidious - grow on blood agar, treated with penicillin.
Streptococcus agalactiae
Causes 60-70% of bacterial pneumonia, and causes otitis media in young children, the "pneumococcus," fastidious- grow on blood agar, alpha-hemolytic, appear as lancet-shaped diplococcic in sputum smear of pneumonia patient, capsule = major virulence factor, pneumococcal vaccine available.
Streptococcus pneumoniae
In Group A - causes childhood sore throat/pharyngitis, scarlet fever due to erythrogenic toxin, rheumatic fever, and other conditions, catalase negative, Beta-hemolytic, fastidious - grow on blood agar, treated with penicillin.
Streptococcus pyogenes
Which of the following organisms produces erythrogenic and pyrogenic toxins, as well as superantigens?
Streptococcus pyogenes
picture 18.28 one clinical sign of meningococcemia
Subcutaneous hemorrhages due to endotoxins released during blood infection
CHAPTER 18 - LECTURE
THE COCCI OF MEDICAL IMPORTANCE
CHAPTER 20
THE GRAM-NEGATIVE BACCILLI OF MEDICAL IMPORTANCE
CHAPTER 19 - LECTURE
THE GRAM-POSITIVE BACILLI OF MEDICAL IMPORTANCE
Describe how the rapid, direct test kit using monoclonal antibodies works for detecting streptococci: picture of streptococcal tests bacitracin disc test (top) monoclonal antibody test (bottom)
The rapid monoclonal antibody test is simpler and faster - positive reaction will be grainy - negative reaction will be just liquid - this is same as the lab 38 that we ran with the staph test Cultivation and diagnosis ensure proper treatment to prevent possible complications • Rapid diagnostic tests based on monoclonal antibodies that react with C-carbohydrates • Culture using bacitracin disc test, CAMP test, Esculin hydrolysis RAPID, DIRECT TEST KIT - This test kit uses monoclonal antibodies (produced in a lab animal) that are specific for Strep. pyogenes, for example - Mix patient specimen with monoclonal test reagent (antibodies in the test kit) - Positive = grainy clumping will form. - Negative = test remains liquid.
Virulence Factors of beta-Hemolytic S. Pyogenes: List the 5 virulence factors of streptococci: Name 3 extracellular toxins that contribute to the virulence of streptococci: Name 3 extracellular enzymes that contribute to virulence of streptococci:
Virulence Factors of beta-Hemolytic S. Pyogenes: Virulence Factors of beta-Hemolytic S. Pyogenes: List the 5 virulence factors of streptococci: Produces surface antigens: - C-carbohydrates - protect against lysozyme - Fimbriae - adherence, short hairs - M-protein - contributes to resistance to phagocytosis - Hyaluronic acid capsule - provokes no immune response - C5a protease (enzyme) hinders complement and neutrophil response most of these have to do with evading the immune system Name 3 extracellular toxins that contribute to the virulence of streptococci: Extracellular toxins: - Streptolysins - hemolysins; streptolysin O (SLO) and streptolysin S (SLS) - both cause cell and tissue injury - Erythrogenic toxin (pyrogenic) - induces fever and typical red rash; erythro means red; pyro means fire; scarlet fever - Superantigens (overreaction from the immune system which is harmful to the body) - strong monocyte and lymphocyte stimulants; cause the release of tissue necrotic factor Name 3 extracellular enzymes that contribute to virulence of streptococci: Extracellular enzymes - Streptokinase - digests fibrin clots; similar to staplylokinase produced by the staphs - Hyaluronidase - breaks down connective tissue - DNase - hydrolyzes DNA
Bacillus anthracis:
What disease does Bacillus anthracis cause? - Anthrax Where are the endospores situated as they develop in vegetative cells? - They are centrally located. Under what conditions does B. anthracis develop endospores? - Any besides in the human body - they are well-fed and comfortable in the body and have no need to form spores there. Endospores are fomed during "stress" Name 3 types of anthrax: 1. Cutaneous - spore enter through skin, least dangerous form. 2. Pulmonary - spores inhaled. 3. gastrointestinal (GI) - spores ingested. What is the characteristic lesion called that develops due to cutaneous anthrax? - Eschar lesion - very dark lesion that crusts and peels off eventually. - We have a few cases every year in the U.S.; it is mostly cutaneous and usually occurs in farmers who deal with the soil How is anthrax treated and prevented? - Treated with cipro, etc. - Can be prevented by vaccination, but we only vaccinate military - requires 6 injections over a year and a half and some people react badly to it (as people can to any vaccine) - cases are sporadic, so not necessary to vaccinate everyone anyway.
Brucella
What disease does Brucella cause and what are other names for this disease? - Brucellosis (can have several other names: malta fever, undulant fever, and Bang disease) is a zoonosis transmitted to humans from infected animals What is the reservoir for Brucella abortus? - cattle: causes miscarriage in cows but not in human What is the reservoir for Brucella suis? - pigs What is the 'cardinal manifestation' of human brucellosis? - fluctuating pattern of fever (which is how it gets the name "undulant fever") lasting weeks to a year
Clostridium botulinum:
What disease does Clostridium botulinum cause? - botulism - intoxication associated with inadequate food preservation What is the source of this disease? - inadequate food preservation (usually from home preservation/canning) What other Clostridium species can cause Clostridial food poisoning? - Clostridium botulinum (gas gangrene organism) - spore-forming anaerobe Where does Clostridium botulinum live? - commonly inhabits soil and water (this is how it gets in home canned foods - you want to get them to high enough temperature and do it sufficiently; get the type with the button that pops up) What toxin does it produce and what effects does it have? - potent toxin, botulin, is released - relaxes the muscles (opposite of tetanus); can relax you to death because you can't contract lungs What is the commercially available form of this toxin called and how is it used? - Botox; for wrinkles; migraines What 3 types of botulism are there, how are they acquired, and what symptoms do they cause? 1. botulism food poisoning (inadequate food preservation) will cause diarrhea, nausea, cramping, etc. 2. infant botulism - caused by ingested spores that germinate and release toxin; flaccid paralysis (causes "floppy baby syndrome"); the reason why honey has a warning not to give to infants under 1 year of age (immune systems can't handle it) 3. wound botulism - spores enter wound and cause food poisoning symptoms How is botulism treated and prevented? - antitoxin (which will bind to the toxin) - penicillin - practice proper methods of preserving and handling canned foods; addition of preservatives picture - infant botulism - "floppy baby syndrome" = flaccid paralysis
Clostridium difficile:
What disease does Clostridium difficile cause? What is another name for this disease? - C diff associated disease (CDAD) - antibiotic-associated colitis Where is it found? - normal resident of colon, in low numbers (held in check by other good intestinal flora What conditions make it able to cause disease? - treatment with broad-spectrum antibiotics kills the other bacteria, allowing C. difficile to overgrow How common is it? - major cause of diarrhea in hospitals - increasingly more common in community-acquired diarrhea How is it treated? - withdrawal of antimicrobials (if possible) - fluid and electrolyte replacement - Severe infections treated with other antimicrobials (oral vancomycin or metronidazole) and newer treatments are using replacement cultures figure 19.6 picture of antibiotic-associated colitis - normal colon (top) - pseudomembranous colitis (bottom)
Clostridium tetani:
What disease does Clostridium tetani cause? - , a neuromuscular disease What do spore-forming vegetative cells look like? - club shaped (because they swell at one end) Where does it reside? - common resident of soil and GI tracts of animals Whom does it commonly affect? - most commonly among geriatric patients (because they may not be current on their vaccination) - IV drug abusers (dirty needles) - neonates in developing countries (get it through the umbilical cord with unsanitary cutting What are possible portals of entry? - spores usually enter through accidental puncture wounds, burns, umbilical stumps, frostbite, and crushed body parts What neurotoxin does it produce and what does this neurotoxin do? - tetanospasmin - neurotoxin causes paralysis by binding to motor nerve endings; blocking the release of neurotransmitter for muscular contraction inhibition; muscles contract uncontrollably How can this disease cause death? - death most often due to paralysis of respiratory muscles (lungs are contracted and can't release) How is tetanus treated and prevented? - antitoxin therapy with human tetanus immune globulin; inactivates circulating toxin (tetanospasmin) but does not counteract that which is already bound - control infection with penicillin or tetracycline; and muscle relaxants - vaccine available; booster needed every 10 years figure 19.1 b and c - Clostridium tetani (bottom) - Clostridium tetani cells look "club-shaped when they form spores)
Francisella
What disease does Francisella tularensis cause? - tularemia: a zoonotic disease of mammals endemic to the northern hemisphere, particularly rabbits (also known as "rabbit fever" because it was first diagnosed in wild rabbits) - transmitted by contact with infected animals, water and dust or bites by vectors (bites from wild rabbits or other wild animals) What is another name for this disease? - rabbit fever
Legionella
What disease does Legionella pneumophila cause? - Legionnaires' disease (Legionellosis) How did it get its name? - 1976 epidemic of pneumonia afflicted 200 American Legion members attending a convention in Philadelphia and killed 29 (It was found to be in the air conditioning system) - found in Florence too in the mall Is this disease fatal? - yes, up to 30% of the time Who is at greatest risk for acquiring this infection? - prevalent in males over 50 What is this organism associated with (where is it found)? - standing water (in air conditioning systems or ponds)
Corynebacterium diphtheriae:
What disease does this organism cause? - diphtheria What is the reservoir of this organism? - healthy carriers Who is at risk for this disease? - non-immunized children How is it acquired? - respiratory droplets Why has the number of cases of diphtheria dropped so dramatically over the last 115 years? - immunization/vaccination Why are there still any cases? - not everyone gets vaccinated and even if they did not everyones system responds to vaccines Describe the 2 stages of this disease: 1. local infection in the throat (lab manual calls it a "bull neck") and a pseudomembrane in the back of the throat which can cause the patient to suffocate (asphyxiation) if it gets large enough (antibiotics and antitoxin treatments can cause this to recede on its own but if it gets too big it may need to be surgically removed - bleeding risk similar to tonsil removal) 2. diptherotoxin which can target organs (primarily heart and nerves) How is this disease diagnosed? - pseudomembrane and swelling indicative (bull neck) - stains - conditions, history - serological assay How is it treated and prevented? - antitoxin (binds of toxin and inactivates it) - penicillin or erythromycin - prevented by toxoid vaccine series and boosters (This is the D of the DTaP, Td, Tdap picture - Corynebacterium diptheriae - gram positive irregular bacilli - pleomorphism - palisades arrangement - granules
Mycobacterium leprae:
What disease does this organism cause? - leprosy What is another name for this disease? - Hansen's disease Can this organism be cultured? - no, it grows so slowly that it has never been cultured in the lab Where does this disease occur and how often? - endemic throughout the world (even in the U.S.) What is the incubation period for this disease? - 2-5 years What are the 2 forms of this disease and what do they affect? 1. tuberculoid: causes nerve damage 2. lepromatous: Biblical type that causes disfigurement and limb loss due to necrosis of the tissues What is the laboratory test for this organism? - acid-fast stain on patient specimens (skin scraping, tissue sample, nasal discharge) - presence of acid-fast bacilli in patient specimens since we can't grow it in culture What is the feather test? - tests for numbness due to nerve damage by this organism How is this disease treated? - complicated treatment - combination of drugs over a long period of time - treatment no longer requires isolation of patients Name 5 other non-tuberculosis mycobacteria and the diseases they cause: - M. avium complex - third most common cause of death in AIDS patients; complex of 2 species/organisms - M. kansaii - pulmonary infections in adult white males with emphysema or bronchitis - M. marinum - water inhabitant; lesions develop after scraping on swimming pool concrete - M. scrofulaceum - infects cervical lymph nodes - M. paratuberculosis - raw cow's milk; recovered from 65% of individuals diagnosed with Crohn's disease *note: other diseases/conditions can cause similar nodule to the skin like leprosy does
Clostridium perfringens:
What diseases does Clostridium perfringens cause? - gas gangrene (what it is most known for) - food poisoning Where are the spores found within the cells and where are they found in the environment? - spores are terminal or sub-terminal (located towards the ends of the cells) (very different from anthrax) - formed in the soil and associated with humans What are predisposing factors? - some type of wound is predisposing factor to getting gas gangrene - we are now better at wound care so we usually see it in untreated diabetic ulcers List the 4 virulence factors it possesses: 1. toxins (destroys tissues, RBCs) 2. collagenase (breaks down collagen) 3. hyaluronidase (breaks down connective tissue) 4. DNase How did the term gas gangrene get its name? - because it produces gas in the muscle fibers; this gas separates the muscle fibers so that they become gangrenous or die off How invasive is Clostridium perfringens? - NOT highly invasive What does it use to form gas in the tissues? - fermentation of muscle carbohydrates as a nutrition source What is myonecrosis? - myonecrosis is destruction or death of the muscle How is gas gangrene treated and prevented? - immediate cleansing of dirty wounds - debridement of disease tissue - large doses of cephalosporin or penicillin (regular natural antibiotics) - hyperbaric oxygen therapy (because it is anaerobic the oxygen will kill it)
ACTINOMYCETES
What do members of this group of bacilli look like microscopically? - nonmotile - filamentous Actinomyces israelii: Where in the body does this organism cause disease? - oral cavity - thoracic - intestines figure 19.26 - picture of man with infection due to A. israeli Nocardia brasiliensis: What kind of disease does this organism cause? - pulmonary disease (lung disease) similar to tuberculosis (TB)
Neisseria gonorrhoeae
What is Neisseria gonorrhoeae also called? - gonococcus What disease does it cause? - gonorrhea, an STD List 2 virulence factors for this organism: - Fimbriae (short hairs bacteria can use to adhere to our cells), other surface molecules for attachment; slows phagocytosis - IgA protease enzyme- cleaves the antibody that is present in mucus which is secretory IgA; you can find this is mucus membranes such as genital tissues What is the only species infected by this organism? - Strictly a human infection What is its survivability of fomites? - does not survive more than 1-2 hours on fomites (toilet seat isn't a good place to contract this) How often is gonorrhea asymptomatic? - Infection is asymptomatic in 10% of males and 50% of females (because of menstruation and more frequent UTIs etc) What are the effects of gonorrhea in males and females? - in both males and females is can cause discharge and infertility - Males - urethritis, yellowish discharge, scarring, and infertility - Females - vaginitis, urethritis, salpingitis (PID) mixed anaerobic abdominal infection, common cause of sterility and ectopic tubal pregnancies - Extragenital infections - anal, pharygeal, conjunctivitis, septicemia, arthritis Why are all newborns treated with silver nitrate or other antiseptic eye treatment immediately after birth? - because this organism can cause eye inflammation and blindness if infected as they pass through birth canal - chlamydia, herpes, HPV, etc can all cause sever eye infections - given to all babies regardless of method of birth (vaginal or c-section) - prevented by prophylaxis immediately after birth What does Neisseria gonorrhoeae look like mcroscopically? - Gram-negative intracellular (neutrophils WBC that attack bacteria) diplococci Is gonorrhea a reportable disease? - yes it is a reportable infectious disease, as are other STDs picture 18.27 - shows WBC with multi lobed nucleus - gram negative diplococci inside the WBC - urethreal puss smear from a male - lab 30 will explain more
Neisseria meningitidis
What is Neisseria meningitidis also called? - the meningococcus List 4 virulence factors of this organism: • 2 mentioned for Neisseria gonorrhoeae - Adhesive fimbriae - IgA protease • as well as: - Capsule - Endotoxin What disease does this organism cause? - Prevalent cause of meningitis; sporadic or epidemic What is the reservoir of this organism? - Human reservoir - nasopharynx; 3-30% of adult population; higher in institutional settings Who is at risk for this disease? - High risk individuals are those living in close quarters (because you need close very contact to transmit this disease) - children 6 months-3 years, children and young adults 10-20 years Where in the body does this organism invade? - Disease begins when bacteria enter bloodstream, cross the blood-brain barrier, permeate the meninges, and grow in the cerebrospinal fluid - cross the sinuses, cross the blood-brain barrier, and get into the cerebrospinal fluid infecting the meninges What is the hallmark symptom of this disease? - stiff neck; a stiff neck should always be of concern because bacterial meningitis can be fatal - Lyme disease also causes a stiff neck but isn't fatal What are the effects of this disease? - Very rapid onset; neurological symptoms; endotoxin causes hemorrhage and shock; can be fatal How is the disease diagnosed? - Gram stain CSF, blood, or nasopharyngeal sample - lab manual shows how to collect nasopharyngeal sample (maybe lab 26) (lab 2 show lab collection section) - culture for differentiation - rapid tests for capsular polysaccharide How is this disease treated and prevented? - treated with IV penicillin G, cephalosporin (both are "old school" natural antibiotics - prophylactic treatment of family members, medical personnel, or children in close contact with patient - primary vaccine (meningicoccal) contains specific purified capsular antigens What lab tests differentiate between the species in the family Neisseriaceae? - mostly sugar fermentation tests picture - shows how it can cross and infect the cerebrospinal fluid
Erysipelothrix rhusiopathiae:
What is the primary reservoir of this organism? - tonsils of healthy pigs What is its portal of entry? - enters through skin abrasion (usually on the hands of farmers), multiplies to produce erysipeloid, dark red lesions What type of lesions does it produce? - multiplies to produce erysipeloid, dark red lesions How is it treated and prevented? - penicillin or erythromycin - vaccine for pigs figure 19.11 - Erysipeloid on hand
Streptococcus pneumoniae:
What is this organism also called? - the pneumococcus What percentage of bacterial pneumonia cases does it cause? - Causes 60-70% of all bacterial pneumonias What does this organism look like microscopically? - Small, lancet-shaped (not perfect cocci and sort of look like rods) cells arranged in pairs and short chains (gram-positive) How is this organism cultivated in the lab? - you need an enriched medium and increased carbon dioxide (since this organism occurs deeper into the respiratory tract) - Culture requires blood or chocolate agar - Growth improved by 5-10% CO2 What is the major virulence factor of Strep. pneumoniae? - like many of the organisms that cause pneumonia/lung infections, its major virulence factor is its capsule - All pathogenic strains form large capsules - major virulence factor What other common infection does Strep. pneumoniae cause besides pneumonia? - Causes pneumonia and otitis media (inflammation of the middle ear) (this is where you would look for the bulging eardrum due to the presence of fluid build up there) (this is different from an outer ear infection such as swimmers ear) How common is carriage of Strep. pneumoniae? - 5-50% of all people carry it as normal flora in the nasopharynx; infections are usually endogenous (i.e. come from your own flora)(fluid build up in the lungs due to the flu or a chest cold is a great environment for this organism to really start growing) Does it exist on fomites? - no, it does not survive will on fomites at all - it is more of a droplet transfer when it is transferred between people - Very delicate, does not survive long outside of its habitat What tests indicate the presence of Strep. pneumoniae? - Gram stain of specimen - presumptive identification (if the lab sees the gram positive lancet-shaped cells, then they will presumptively assume that is strep. pneumoniae pneumonia and start antibiotic treatment) - Quellung test (= capsular swelling reaction - this is an antibody test) How is Strep. pneumoniae treated and prevented? - Traditionally treated with penicillin G or V as a primary first choice - Two vaccines available for high risk individuals: 1. Capsular antigen vaccine for older adults and other high risk individuals - effective 5 years 2. Conjugate vaccine for children 2 to 23 months
table 18.5 scheme for differentiating gram-negative cocci and coccobaccilli
What lab tests differentiate between the species in the family Neisseriaceae? - mostly sugar fermentation tests
What species does the viridans group include? How much of a concern is the viridans group?
What species does the viridans group include? • Large complex group - Streptococcus mutans - S. oralis (oral cavity) - S. salivarus (saliva) - S. sanguis - S. milleri - S. mitis • Most numerous and widespread residents of the gums and teeth, oral cavity, and also found in nasopharynx, genital tract, skin How much of a concern is the viridans group? • Not very invasive; dental or surgical procedures facilitate entrance • Persons with preexisting heart disease are at high risk - subacute endocarditis - Blood-borne bacteria settle and grow on heart lining or valves - someone with heart disease who needs a root canal or tooth extraction will take antibiotics prophylactically before having that work done
Propionibacterium acnes:
What type of infection does this organism cause? - acne Where does it reside? - common resident of pilosebaceous glands (hair follicles and oil glands) *interesting note: - people who have acne have one strain of this organism and people who don't have a different strain
Bacillus cereus:
Where is Bacillus cereus found? - airborn and attached to dust particles in the air Is it easily eradicated from the environment? - no, it's everywhere - as soon as you clean a surface with bleach, etc., more dust particles will immediately land again What type of disease does it cause? - 24-hour diarrhea, typically not serious and not requiring treatment How is it treated? - no treatment required
Pseudomonas
Where do pseudomonads live? - Primarily in soil, sea water, and fresh water; also colonize plants and animals How versatile are Pseudomonas species? - very versatile; can live in many different environments and use various things as nutrients Pseudomonas aeruginosa: figure 20.1 - picture showing Pseudomonas aeruginosa - monotrichous (1 flagella) in terms of its flagellum - motile (can be hard to tell in lab though because of only having 1 flagella) How common is this organism and what problems does it cause? - common inhabitant of soil and water - intestinal resident in 10% normal people - opportunistic pathogen What typically predisposes one to Pseudomonas aeruginosa infections? - hospitalization because it is a frequent contaminant of ventilators, IV solutions, anesthesia equipment - having cystic fibrosis What are unusual characteristics of infections caused by this organism? - grapelike odor - greenish-blue pigment (pyocyanin); it will do this on a plate, test tube, and wound of a patient How does this organism affect healthy people? - UTI Does this organism tend to be drug resistant and how important is drug susceptibility testing? - it tends to be extremely drug resistant so it is important to run a susceptibility test such as a Kirby-Bauer test on an infection caused by this organism (or an E-Test or broth dilution test) - Pseudomonas aeruginosa shows as much drug resistance as Staph (like Staph aureus - MRSA) can show Related Gram-Negative Aerobic Rods: - genera Burkholderia, Acinetobacter, Stenotrophomonas • Similar to pseudomonads - wide variety of habitats in soil, water, and related environments - obligate aerobes; do not ferment sugars - motile, oxidase positive - opportunistic Burkholderia: - Burkholderia cepacia: active in biodegradation of a variety of substances; opportunistic agent in respiratory tract, urinary tract, and occasionally skin infections; drug resistant (most likely to be contracted by an immunocompromised patient) - Burkholderia pseudomallei: generally acquired through penetrating injury or inhalation from environmental reservoir; wound infections, bronchitis and pneumonia, septicemia (more prevalent in the eastern hemisphere - so we might misdiagnose it here due to its rarity) Acinetobacter and Stenotrophomonas: - Acinetobacter baumanii: nosocomial and community acquired infections; wounds, lungs, urinary tract, burns, blood; extremely resistant - treatment with combination antimicrobials - Stenotrophomonas maltophilia: forms biofilms; contaminant of disinfectants dialysis equipment, respiratory equipment, water dispensers, and catheters; clinical isolate in respiratory soft tissue, blood, CSF; high resistance to multidrugs (usually affects dialysis or catheterized patients)
Causes "black plague," vector = fleas, bubonic, septicemic, and pneumonic (contagious, fatal) forms
Yersinia pestis
Describe how the CAMP test works for identifying streptococci:
beta-hemolytic streptococci - developed by a group of 4 scientists - CAMP stands for their names - you take a specimen of presumptive group B strep and streak it back and fourth on a blood plate (like on the left side) --> then streak it across (like in the middle) --> put the 2 disks (SXT and bacitracin) on the left streaked side --> then on the you cross streak it with staph aureus (on the right side) essentially you are doing 4 tests on one plate - looking for beta-hemolysis (middle area I think?) - resistance to A disk (bacitracin) - resistance to SXT disk - looking for area of increased hemolysis when you cross streak it with the beta hemolytic staph aureus Beta-hemolytic Staph. aureus is cross-streaked on a blood agar plate with presumptive Group B Strep (strep agalactiae) - if a region of greater hemolysis appears between the two, then the reaction is CAMP test positive (and therefore you do have group B strep). If not, it is negative (and it is another type of strep - pyogenes perhaps)
What is the main virulence factor for Streptococcus pneumoniae?
capsule
figure 19.25
picture of chronic swimming pool granuloma caused by M. marinum
figure 19.24
picture of feather test for leprosy
figure 19.21
picture of leprosy lesions
figure 19.22
picture of the lepromatous form
Present in the oral cavity, can cause dental caries, can cause more serious infection in heart patients (take antibiotics prophylactically for invasive dental work).
viridans Streptococci
Describe what alpha vs. beta hemolysis looks like on a blood agar plate: α-hemolysis β-hemolysis
α-hemolysis causes partial breakdown of the RBC which turns a green color which we call greening α-hemolysis β-hemolysis is a worse type of hemolysis because it is the complete destruction/breakdown of the RBC which causes clearing zones of β-hemolysis picture with - Streptococcus pyogenes with clearing zones of β-hemolysis - Streptococcus pneumoniae displaying greening α-hemolysis
How are Groups A and B treated and prevented?
• Groups A and B are treated with penicillin or secondary antibiotics for those with penicillin allergies • Long-term penicillin prophylaxis for people with a history of rheumatic fever or recurrent strep throat • Enterococcal treatment usually requires combined therapy
How were the Lancefield groups determined? Developed by Rebecca Lancefield
• Lancefield classification system based on cell wall carbohydrate•/Ag - 17 groups (A, B, C,....). An antigen (Ag) is anything, such as a cell marker, that causes a immune response. • Another classification system is based on hemolysis reactions b-hemolysis - A, B, C, G and some D strains a - hemolysis - S. pneumoniae and others collectively called viridans
