PTA124 Pathology - Chapter 5
colonization of organisms
-"asymptomatic -microorganisms may be present in the tissue of the host yet not cause symptomatic disease (host is a carrier)
Overview of Group B Streptococci
-"streptococcus agalactiae" is the leading cause of neonatal pneumonia, otitis media, meningitis and sepsis -a part of the normal vaginal flora and are found in more than 20% of women. -neonates may demonstrate hypotension, pneumonia, bacteremia or meningitis. -Treatment: rapid administration of IV antibiotics. CDC requires pregnant women to be screened for group B streptococci. -incidence: 5 to 10% of healthy adults and 20 to 40% of children.
Overview of STD's and STI's
-1 out of 4 sexually active people is carrying an infection other than HIV. -STDs and STIs may be completely asymptomatic and are less likely to be diagnosed until serious problems develop. -women are more susceptible to reproductive cancers, infertility and contracting other STDs and STIs once infected -prevention is the most important key
Overview of infections in drug users
-19.5 million people or 8.2% of the population are found to be using drugs in 2003 -HIV and hepatitis are commonly transmitted with injection drug use -Drug users have a high incidence of bacterial infections due to the various drugs used, route and sites of administration and preparation. -Drug users are more likely to develop a respiratory tract infection than others such as pneumonia -musculoskeletal infections may occur in unusual places
What are the post infection syndromes for Lyme disease?
-Also known as chronic Lyme disease, resembles fibromyalgia or chronic fatigue syndrome: disabling fatigue, severe headache, diffuse muscle or joint pain, cognitive difficulties and sleep abnormalities -symptoms may emerge with the infection or soon after treatment, persisting for months to years
Pathogenesis and clinical manifestations of Influenza
-Can progress rapidly to pneumonia, genetic mutations occur with 100s of variations -Onset is usually abrupt with a high fever, chills, malaise, muscle aches, headache, sore throat, nasal congestion, nonproductive cough, and for children: nausea, vomiting and otitis media. -The fever lasts about 1 to 7 days
There has been a recent increase with what illness?
-Clostridium difficile-associated illness, correlated with the emergence of a hyper virulent C. difficile strain, increasing resistance to the fluoroquinolones
Stage 2 clinical manifestations for Lyme disease
-Disseminated infection: occurs within days to weeks after the spirochete spreads to the nervous system, heart and joints. -15% of cases develop neurologic symptoms -mild headache, stiff neck and difficulty with mentation; cranial neuropathies such as Bell's palsy and radiculopathies. -50% may develop painful Lyme arthritis characterized by unilateral inflammation and swelling in the large joints (knees) -Overall migratory musculoskeletal pain (often lasts only hours or days at a given location)
Clinical manifestations of VZV
-Fever, malaise, rash (dewdrop on a rose petal) with vesicle on an erythematous base, pain and itching during the eruption of the vesicles, pneumonitis and encephalitis following the infection, secondary bacterial skin lesions, and postherpetic neuralgia (debilitating nerve pain from chronic shingles).
Clinical manifestations of HSV! and 2
-HSV 1 typically affects the mouth and oral cavity, causing vesicles in the mouth, throat and around the lips. -systemic symptoms of HSV 1: fever, myalgia and malaise -HSV 2: vesicles form in the genitourinary tract. Lesions are usually painful, small, grouped and vesicular with possible burning and itching. -Blister-like lesions break and weep after a few days leaving ulcer-like sores that crust over and heal in 1-2 weeks.
Incidence and transmission of Lyme disease
-It is an infectious multi systemic disorder caused by the tick-borne spirochete "Borrelia burgdorferi" -In the US, it is transmitted to humans only by the deer or black-legged tick in the northeastern and north central part; also by the western black-legged tick on the west coast -Lyme disease is the most prevalent vector-borne infectious disease in the US -Often seen in late spring and summer months
Overview of Staphylococcal infections (Staph)
-More than 30 species of staphylococci but only a few clinically relevant -nomotile and anaerobic, hardly able to survive on inanimate objects -incidence: Staphylococci bacteria are the leading cause of nosocomial and community-acquired infections (13% of all hospital infections/year) -affects all ages and involves the blood, skin, lung, soft tissue, joints and bones -germ normally found on the skin or inside nose that are usually asymptomatic
Pathogenesis and clinical manifestations for Respiratory Syncytial Virus
-People usually shed the virus for 3 to 8 days (3 to 4 weeks for infants) -Rapid diagnosis can be made by viral antigen identification of nasal washings using an enzyme-linked immunosorbent assay (ELISA) -Signs include a low-grade fever, tachypnea, wheezing, hyper inflated lungs, decreased gas exchange and otitis media. -Treatment: hydration, humidification of inspired air, ventilatory support and avoidance of tobacco smoke, cold air and air pollutants.
Pathogenesis of Staphylococcal infections
-S. aureus cannot invade through intact skin or mucous membranes (must be damaged skin) -once inside, organism is a virulent pathogen secreting membrane-damaging enzymes that harm host tissues and can spread via the blood stream.
Risk factors/Transmission of Staphylococci infection
-Spreads by direct contact with colonized surfaces or skin. -Colonization occurs more frequently in individuals with diabetes who are insulin dependent, HIV positive, clients receiving hemodialysis, IV drug users and people with chronic skin lesions. -Individuals more likely to develop the infection include surgical & burn patients, individuals with diabetes who require insulin, anyone who is neutropenic, individuals with prosthetics, chronic skin disease, rheumatoid arthritis or catheters and people undergoing corticosteroid therapy.
Overview of cytomegalovirus (HSV 5)
-a commonly occurring DNA herpesvirus, it increases in frequency with age. -1% of newborns have it and 4/5 adults older than 35 have CMV -transmitted by human contact with infected secretions (urine, breast milk, blood, feces, semen and vaginal and cervical secretions) and also through the placenta & transplanted organs. -can remain dormant
What is a fever and what abnormalities could cause it?
-a fever is a sustained temperature above normal -abnormalities of the hypothalamus, brain tumors, dehydration or toxic substances affecting the temperature-regulating center of the hypothalamus.
infectious disease
-a host-parasite interaction causes obvious injury and is accompanied by one or more clinical symptoms
Overview of pseudomonas aeruginosa
-a major opportunistic pathogen and one of the most common hospital & nursing home (nosocomial) acquired pathogens. -associated with pneumonia, wound infections, urinary tract disease, sepsis, burns, cystic fibrosis, chronic lung diseases, neutropenia associated with chemotherapy, and diabetes -thrives on moist environmental surfaces and is antibiotic resistant -spread by contact
Protozoa
-a single cell unit (group of non differentiated cells loosely held together) -cell membranes rather than cell walls -nuclei are surrounded by nuclear membranes -example: malaria
Incidence of HSV 1 and 2?
-about 70% over 12 years old carry HSV 1 (cold sores and 20% older than 12 years old have HSV 2, responsible for genital herpes -both can infect any visceral organ or mucocutaneous site
Clinical manifestations of staphylococcal infections?
-abscess formation, fever, chills, pain, swelling over infected area, restlessness and headache -treatment: drainage of abscess, removal of prosthetic devices, antibiotics & supportive therapy
Pathogenesis of Lyme disease
-after about 36 hours, the bacteria is passed into the host when the tick injects spirochete-laden saliva into the host. -After incubating for 3 to 32 days, the spirochetes cause an inflammatory response resulting in skin lesions at the site of the bite -The body activates an immune response producing cytokines and antibodies against the bacteria -B. burgdorferi can survive for years in certain areas of the body
Common symptoms of the CNS?
-altered level of consciousness, confusion or seizures -headaches -photophobia -memory loss -stiff neck or myalgia
Overview of infectious mononucleosis (HSV 4)
-an acute infectious disease caused by the Epstein-barr virus (EBV) -primarily affects young adults and children -95% of people 35 to 40 years have been infected (both genders affected equally) -transmission is through contact with oral secretions, blood or transplanted organs.
Overview of Clostridium difficile-associated disease (CDAD) or C. difficile (C diff)
-an anaerobic, spore-forming bacillus that can cause symptoms ranging from mild diarrhea to severe colonic inflammation, leading to death -increasingly recognized within long-term care facilities or acute care or short-stay hospitals (high rate of antibiotic use) -incidence: increasing rapidly in the US and Canada, no sign of decline
Rickettsiae
-animal pathogens that produce disease in human beings through the bite of an insect vector -small, gram negative, obligate intracellular organisms -require a host for replication
communicable disease
-any disease whereby the causative agent may pass or be carried from one person to another directly or indirectly
Pathogenesis, clinical manifestations and treatment of Hepatitis B
-body responds to infection with special disease-fighting cells, but they can lead to liver inflammation -manifestations vary with both acute & chronic, hepatitis & extra hepatic manifestations can also occur -treatment: post exposure prophylaxis, antiviral medications or liver transplant (immunization is available)
Pathogenesis for C. difficile?
-change in the protective flora of the enteric system induced by antibiotics may cause overgrowth by C. difficile -inactive spore form coverts to the vegetative form which then replicates and produces toxins
What are some of the most common causes of prolonged fever when someone's temperature exceeds 102 degrees?
-clostridium difficile colitis, heat stroke, HIV infection and transfusion reactions
What are the 5 main routes of transmission?
-contact (direct or indirect), airborne (less than 5 microns), droplet (greater than 5 microns), vehicle (common course to multiple susceptible hosts) and vector borne
What are some reasons why the elderly are more susceptible to infection?
-decrease in T cells and increase in # of memory T cells which have a slower response -atrophic skin more easily damaged, decreased cough and gag reflexes, physical decline, decreased mucociliary activity (pneumonia) and psychologic impairment
What are the 5 basic laboratory techniques that can be used to diagnose infectious diseases?
-direct visualization of the organism (microscope) -detection of microbial agents -search for clues produced by the host immune response to specific microorganisms (characteristic cell changes) -detection of specific microbial nucleotide sequences -isolation of the organism in a culture
Common symptoms of the Genitourinary system?
-dysuria or flank pain (painful urination) -hematuria (blood in the urine) -oliguria (low output) -urgency & frequency
What are some systemic symptoms of infectious disease
-fever, chills, sweating, malaise, nausea and vomiting. -change in blood composition may occur (more leukocytes) -older adults may experience change in mentation.
Pathogenesis and clinical manifestations of Infectious mononucleosis
-fever, sore throat and tender cervical lymphadenopathy; headache, malaise and abdominal pain -incubation period is 4 to 6 weeks -often an increase in WBC count with an elevation in atypical lymphocytes -spleen may enlarge 2 to 3 times its normal size and affected individuals are at risk for splenic rupture. -symptoms subside 6 to 10 days after onset of disease but may persist for weeks. -studies show an association between infectious mononucleosis and multiple sclerosis
Mode of Transmission for C. difficile?
-health care facilities via the fecal-oral route after contamination of the hands of HCWs and patients with oral ingestion of the causative organism -may come from nonhuman reservoirs
Overview of prostheses and implant infections
-implantation of any device with synthetic material can lead to serious life-threatening infections and reoperations have a higher risk -early detection of infection can reduce complications and morbidity
Pathogenesis of HSV 1 and 2
-infection occurs through a break in the mucous membranes of the mouth, throat, eye or genitals or via minor abrasions in the skin -the virus will multiply locally and enter the peripheral sensory nerves and migrate to the CNS and reside there.
Prions
-infectious particles containing protein without nucleic acids -transmitted from animals to humans and are characterized by a long latent interval in the host -example: mad cow disease
Pathogenesis of Varicella Zoster Virus
-initially multiplies at the site of entry, with viremia occurring 4 to 6 days after infection -virus then disseminates to other organs such as the liver, spleen and sensory ganglia and further replicates in the viscera. -incubation period is 14 to 16 days -VZV is present in white blood cells up to 5 days before the rash is present -individuals remain contagious until the lesions have crusted.
First line of defense
-intact skin and mucous membranes, oil and perspiration on skin, cilia in respiratory passages, gag and coughing reflexes, peristalsis in the GI tract, and the flushing action of tears, saliva and mucus. -all inhibit invasion of pathogens and remove them before they multiply. -nonspecific
Transmission of HSV 1 and 2
-intermittent, asymptomatic shedding is common: typical time of transmission is during shedding
Transmission, pathogenesis and clinical manifestations of Group B streptococci
-it is spread through direct contact or droplets of respiratory secretions -organism colonizes in oropharynx spreading hematogenously into other organs -manifestations: fever, chills, pleuritis, dyspnea with productive cough or purulent sputum, headache, stiff neck, nausea, vomiting or mental status changes
Overview of the Varicella Zoster Virus (HSV 3)
-known as chickenpox or shingles, 10 to 20% develops the secondary or reactivation form (300,000 cases of shingles a year) -High risk to adults over 50 years and anyone immunocompromised -acquired from contact with airborne droplets or by direct contact -persists in the body as a latent infection
Stage 3 clinical manifestations for Lyme disease
-late persistent infection: apparent weeks to months later where 60% of individuals left untreated will have intermittent arthritis associated with marked pain and swelling especially in the large joints. -it is rare for individuals to develop erosions or permanent joint abnormalities
Most common resistant bacteria?
-methicillin-resistant Staphylococcus aureus (MRSA) -vancomycin-resistant enterococci (VRE) -multidrug-resistant mycobacterium tuberculosis -vancomycin-resistant S. aureus strains -multidrug-resistant pseudomonas aeruginosa
What are some examples of infectious diseases spreading more rapidly compared to the past?
-misuse & overuse of antibiotics, large number of children in daycares, sicker populations in hospitals, antibiotics in agriculture, environmental pollutions & weather disasters
Strep Throat (streptococcal pharyngitis)
-most commonly in children (15-36% of all sore throats) -incubation is 1 to 5 days and manifestations may include fever, sore throat with pain on swallowing, beefy red pharynx, edematous tonsils with exudate, swollen lymph nodes along jaw line, generalized malaise and weakness, anorexia and occasional abdominal discomfort. -treatment is with antibiotics to avoid post streptococcal syndromes
Common symptoms of the GI system?
-nausea, vomiting or diarrhea
Latent infection
-occurs after a microorganism has replicated but remains dormant or inactive in the host, sometimes for years.
Overview of Group A streptococcal infections
-one of the most common bacterial pathogens of any age -Causes disease of diverse organ systems ranging from skin infections to acute self-limited pharyngitis to post infectious syndromes like rheumatic fever -(GAS) typically transmitted via contact with respiratory droplets or food borne transmission. In a health care setting it may be spread after contact with infected secretions
Pathogenesis & Manifestations of Group A Streptococci
-organism colonizes in throats, skin lesions, subcutaneous tissues, fascia or muscle producing several pyogenic endotoxins. -Clinical manifestations include fever, sore throat, edema, macule, rash, redness and swollen lymph nodes
Why is early recognition of infection an issue with older adults?
-people underreport symptoms -presentation is often vague or atypical -symptoms are difficult to assess -fever temps are masked by a low basal body temp (lower threshold for infection) -first symptoms of infection may be confusion, memory loss or other changes in mental status
Common symptoms of the cardiovascular system?
-petechial lesions -tachycardia -hypotension -change in pulse rate (may increase or decrease depending on the type of infection)
Pathogenesis of pseudomonas aeruginosa
-produces an array of proteins that help it attach, invade and destroy host tissue -avoids host inflammatory and immune defenses -surface molecules on injured epithelial cells serve as binding sites -many strains produce a proteoglycan that surrounds the bacteria, protecting them from mucociliary action, complement and phagocytes.
What are some of the most common causes of prolonged fever when someone's temperature does not exceed 102 degrees?
-pulmonary emboli, hepatitis, TB, dehydration and catheter-associated bacteriuria
Common symptoms of the integumentary system?
-purulent drainage from abscess, open wound, or skin lesion -skin rash or red streaks -bleeding from gums or into joints; joint effusion or erythema
Mycoplasmas
-self-replicating bacteria with no cell wall components and very small genomes -require a strict dependence on the host for nutrition and sustenance -able to pass through many bacteria-retaining filters/barriers because they are so small -antibiotics rarely have an effect
Bacteria
-single-celled microorganisms with cell walls -can grow independently (on artificial media) without the need for other cells -example: staph
Chlamydiae
-smaller than rickettsiae and bacteria but larger than viruses -always contain both DNA and RNA and are susceptible to antibiotics -depend on host cells for replication (STD)
Pathogenesis and clinical manifestations of Cytomegalovirus (HSV 5)
-spreads through the body via lymphocytes or mononuclear cells, where it produces inflammatory reactions. -usually asymptomatic or manifests like infectious mononucleosis but rarely causes pharyngitis or adenopathy -10 to 15% of those infected are born with hearing loss, vision impairment or degrees of mental retardation and the infection is deadly for 20 to 30% of neonates -other complications include diffuse interstitial pneumonitis leading to respiratory distress syndrome, hepatitis, adrenalitis, intestinal ulcerations and calcifications around ventricles in neonates.
Viruses
-subcellular organisms made up only of RNA or DNA -must invade a host cell & replicate the same virus to survive -not susceptible to antibiotics -smallest known organisms
What factors are involved in the chain of transmission?
-successful transmission depends on: a pathogenic agent, a reservoir, a portal of exit, a mode of transmission, a portal of entry into host and a susceptible host.
Incidence and transmission of Influenza
-susceptible to young children with chronic diseases, immunocompromised adults and the frail elderly. -Occurs between late fall and early spring (between December & March), caused by influenza viruses A or B (epidemic proportions) -Transmits by inhalation of aerosolized virus or by direct contact -Incubation period is 1 to 4 days
Clinical manifestations of pseudomonas aeruginosa
-symptoms vary with the site of infection and state of host defenses -often invades small arteries and veins, producing vascular thrombosis and hemorrhagic necrosis (lungs and skin) -Bacteremia, dissemination, sepsis, infection of the respiratory tract (pneumonia) and other parts of the body.
Common symptoms of the upper respiratory system?
-tachypnea, cough, dyspnea, hoarseness, sore throat, nasal drainage, sputum production, oxygen desaturation, decreased exercise tolerance and prolonged ventilatory support
Stage 1 clinical manifestations for Lyme disease
-the early localized stage: occurs within days after the bite where 80% of individual have a red, expanding rash -Rash resolves spontaneously without treatment within an average of 4 weeks -Flulike symptoms include fatigue, chills, fever, headache, lethargy, myalgias or arthralgia. -early symptoms are mild
third line of defense
-the immune response -responds in a specific manner to individual pathogens
second line of defense
-the inflammatory response -inflammation is a local reaction to cell injury of any type -nonspecific
Incidence and transmission of the Respiratory syncytial virus
-the leading cause of lower respiratory tract infections in children worldwide (75,000-125,000 hospitalizations) -nosocomial transmission is common -transmitted through large droplets during close contact or indirectly by hands or fomites that are contaminated with RSV -covers annual outbreaks of pneumonia, bronchiolitis and tracheobronchitis
Overview of Hepatitis C
-the most common etiologic agent in cases of non-A, non-H hepatitis in the US. -significant association between acquisition of disease and health care employment. -accidental exposures (needle sticks or cuts with sharp instruments) are the highest risk vehicle for transmission -incubation period is 6 to 7 weeks: nearly all individuals with acute infection will have chronic (3-6 months). -no vaccine available
incubation period
-the period between the pathogen entering the host and the appearance of clinical symptoms (days to months)
Overview of Hepatitis B
-the risk of acquiring HBV is dependent on the degree of exposure to blood and the presence of HBV e antigen from the source. -can be transmitted via percutaneous injuries or by direct or indirect contact with blood. -blood contains the highest amount of infected particles and can last up to 1 week on environmental surfaces.
period of communicability
-the time period when an organism can be shed
Fungi
-unicellular to filamentous organisms -occur as yeasts or molds (little cellular specialization) -possesses hyphae (filamentous outgrowths) surrounded by cell walls and containing nuclei
Overview of Herpes Virus 6, 7 & 8
Incidence: common in children (90% infected by age 2) -clinical manifestations: 3 to 5 days of high fever followed by a macular rash on neck & trunk (roseola), runny nose and fussiness
What is the second leading cause of death among infectious diseases?
Tuberculosis, killing about 2 million people a year -HIV is the leading cause of death
Infection
a process in which an organism establishes a parasitic relationship with its host
Treatment of infectious mononucleosis?
rest & supportive care, no specific interventions alters or shortens the process
Mycobacteria
rod-shaped aerobic bacteria (TB)
