Microbiology of Skin and Muscle Tissue
Characteristics of Elementary bodies
**Infectious cells that cannot grow on their own - must e taken up by the right type of eukaryotic cell so can differentiate into Reticulate body -Smaller than Reticulate bodies -Rigid cell wall -Relatively resistant to sonication -Resistant to trypsin - 1:1 DNA/RNA content -Toxic for mice -Isolated organism infectious -Adapted for extracellular survival
Characteristics of Reticulate bodies
**Once elementary bodies have differentiated into these, binary fission occurs - more elementary bodies are released into cell to spread** -initial body -Larger than elementary bodies -Fragile cell wall -Sensitive to sonication -Lysed by trypsin - 1:3 DNA/RNA content -Non-toxic for mince -Isolated organisms not infectious -Adapted for intracellular growth
Streptococcus pyogenes -What is it also known as? -What is it and how does it infect? -What are the consequences of its infection ---> common cause of what type of infection?
-Also known as group A streptococci --> -"flesh-eating" bacteria -This is an opportunistic skin & muscle tissue pathogen (can infect from breaks in the skin in particular) -Commonly causes cellulitis (common bacterial infection of the skin) -It can also lead to necrotizing fasciitis (bacterial skin infection that is flesh eating) and myositis (inflammation of muscles used to move your body) - "flesh-eating" bacteria
Streptococcus agalactiae -What is it also known as? -What can it do with birth?
-Also known as group B streptococci - very common the surface of the skin & is mostly commensal --> But, if a pregnant women is going through child birth & has Strep. agalactiae, on their skin or in their bowels, and it is transferred to newborns, it can cause severe, life-threatening infections with a 5% mortality rate -Pregnant women are now tested so antibiotics can be administered during child birth
Treponema pallidum -Phylum? -Causative agent of what and how contagious? -How likely is someone to become infected? -Why is it historically important?
-In Phylum Spirochaetes -causative agent of syphilis --> Syphilis is not highly contagious --> From a single exposure, there is about a 1 in 10 chance of contraction of syphilis from an infected individual -This was historically important & pervasive type of disease that, in some locations, caused entire segments of society to fall apart at certain points in history (especially around armies) --> Men in the army were separated from women almost entirely bc so many people were infected with syphilis at the time
Streptococcus -Phylum? -Order? -How do the get energy? -Where are they often found?
-In the phylum Firmicutes and in the order Lactobacillales -Streptococcus are facultative anaerobes that are non-spore forming -Streptococcus is common on the skin as well
What is an opportunistic infection? -Opportunistic infections of Staph. aureus --> where do they infect? --> What happens if they're uncontrolled? --> how easy are they to rid?
-Like E. coli, will cause opportunistic infections (take advantage of an opportunity that is not normally available) -Opportunistic infections of Staph. aureus are particularly common in immunocompromised individuals (can be hospital acquired) -Often infect somewhere on the skin (where sweat glands or hair follicles have been blocked up or where there is a boil or wound) -If infections are uncontrolled, can lead to more widespread, systemic infections are relatively common & are pretty easy to clear up w antibiotics -more of a major problem when they are antibiotic resistant (which is more likely to lead to systemic infections) -can also produce toxins on food (they are a pretty common source of food poisoning as well)
Normal microbiota - Urinary tract -Where are microbes typically found? -What areas are microbe-free? -Most common cause of UTIs?
-Microbes typically found on the skin or in the intestine are commonly found in the distal portion (of the urethra) -upper portion of the urethra and the bladder is microbe free (in healthy individual, no microorganisms are found in that part of the body unless there is an infection) - most common cause of urinary tract infections is E. coli (there can be other types of bacteria that would cause similar types of opportunistic infections)
Skin -How does it contribute/relate to the immune system? -Conditions of skin and how it affects microbial growth (3)
-Protected by the immune system & physical barrier -Conditions of the skin restrict microbial growth in general because the skin is: 1) Dry 2) Has a high concentration of salts 3) Sweat glands secrete moisture and fatty acids *These conditions essentially create a hostile environment for microorganism to grow in
Staphylococcus - Phylum? -2 common strains? --> In what class are these strains? -What are they? -How do they get their energy?
-Staphylococcus is in the phylum Firmicutes, Staph. aureus and Staph. epidermidis are in the class Bacilli - facultative anaerobes and non-spore forming cocci -are normal skin, nose, and mouth bacteria
Consequences/symptoms of Neisseria gonorrhoeae in men & women -Why is it a problem with childbirth?
-Symptoms are diff. for males & females -disease can be treated w antibiotic, but it can also clear up on its own (don't necessarily carry around gonorrhea for the rest of your life) -Males experience a burning discharge -Females often have no immediate symptoms (but can also have a similar discharge) -Over longer periods, it can lead to pelvic inflammatory disease, which can lead to sterility in women -also an even larger problem during child birth - if it infects the eyes during child birth, it can lead to blindness fairly readily -now in the US we give antibiotics or silver iodide drops into newborns' eyes prophylactically to insure that no infection occurs after birth
Prevalence of Syphilis in the US -How us it treated?
-Syphilis was nearly eliminated in the United States prior to 2000, but it has increased in prevalence over the last 20 years, with over 10,000 cases per year (1 case per 100,000) -It is usually treatable with penicillin (antibiotics)
Streptococcus virulence factors
-They produce extracellular enzymes that break down host molecules or dissolve clots -have a special protein known as the M protein and special capsules made from hyaluronic acid (similar to human connective tissue) that help it resist phagocytosis -Have a compound in the hyaluronic capsule that helps them resist or avoid the acquired immune system (because it simulates our own tissue) -also produce toxins that kill leukocytes (streptolysins)
Normal microbiota - Female Genital Tract - Why is it unique and what creates this? - What can cause change? - What causes Urethritis (infection)?
-Unique bc of the low pH that is created by Lactobacillus acidophilus (and the related Lactobacilli - which are anaerobes that produce lactic acid) - maintains a pH of about 4.5 ---> This results in 1 of the least diverse parts of the body -The bacterial community can change with the menstrual cycle (since there are dramatic changes during that time) -Urethritis (infection) can be caused by opportunistic pathogens (like E. coli) as well as more specialized pathogens
Staphylococcus -Staph. epidermidis --> how common? --> What does it do?
-found on almost everyone -Staph. epidermidis is a very common skin resident (on ~80% of ppl) that has been recently found to produce a compound that it secretes as an antimicrobial to try to get space away from other microbes that may be found on the skin -Staph. epidermidis was actually found to be protective against skin radiation, which causes cancer (may be used in the future as a skin probiotic to prevent sunburn and skin cancer)
Virulence factors in pathogenic strains of Staphylococcus (aureus)
-has a ton of diff. potential virulence factors, such as: 1) A slime layer, which helps in adherence & prevention of phagocytosis 2) Catalase, to help survive in oxygenated environments 3) Proteases, which are involved in destruction of our tissue as well as protein based parts of our immune system 4) Coagulase and hemolysin, which are other types of toxins --> There are other toxins as well --> Enterotoxin (something such as teichoic acid or peptidoglycan since it is a Gram-positive and doesn't have LPS) 5) Antibiotic resistance genes (such as methicillin resistance genes)
Physical characteristics of Phylum Spirochaetes
-have a Gram- cell wall w an additional outer layer called an outer sheath--> constructed from a combo of lipids, carbohydrates, & proteins have a periplasmic space, but also have another space bw the outer membrane & the outer sheath, & w/i this space, there are flagella (axial fibril or endoflagellum), which are basically wrapped around cell -Rather than their flagella being on the outside, they are essentially inside the organism bc they enclose them in the outer sheath -As they turn their flagella, can constrict & flex their shape to make it more of a corkscrew (more curved), & they can release that & let it relax -This provides them w their own unique form of motility, where they change their shape, providing them w a corkscrew-like motion --> This type of motion makes them able to move around in liquids & through fibrous tissue to some extend by burrowing & corkscrewing their way in
Phylum Spirochaetes
-have a flexible helical shape -very common in the environment (since it is an entire phylum, they are extremely diverse & are found in many diff. habitats) -often associated w animals (animal guts, mouths, etc.), but they are also found in sediments
Chlamydia trachomatis
-most commonly reported STD in the US - ~426 cases per 100,000 individuals in 2010 -Infections are usually asymptomatic or minor -There are a lot of carriers of Chlamydia -actual infection rate is estimated to be 6.8% -Complications: --> Infected ppl can experience burning discharge, which often subsides on its own -can lead to pelvic inflammatory disease, which can lead to sterility as well as chronic pain or ectopic pregnancy (life threatening for mother & baby) -can also cause infections in newborns at birth, which is another reason we treat newborns prophylactically
Neisseria gonorrhoeae -phylum -Class -What infection does it cause and what is the case rate? -How does it cause infection? - What is special about it and what about it contributes to reinfections?
-phylum Proteobacteria - Class β-Proteobacteria -2nd most common STD reported in the US -case rate of about 1 in 1,000 -able to grow inside of epithelial cells -Causative agent of gonorrhea --> Binds to the epithelial cells in the urethra --> can cause an infection just thru the binding to the epithelial cells, but it can also be phagocytosed & spread to underlying tissue -Survives in phagocytic cells - has the ability to vary surface proteins regularly, which can lead to reinfection even if we have acquired immune response & memory cells against gonorrhea (bc the surface proteins become diff.)
After contraction, there is a series of stages of Syphilis......
1) Initially, the symptoms of infection are a sore or chancre on the genitals (this is known as the initial stage or the primary chancre)--> This occurs a few weeks to a few months after infection 2) The infection becomes seemingly dormant (the Spirochaetes are still growing) & the spread thru the blood & lymph to many diff. parts of the body such as the skin, bone, nervous tissue, etc. 3) After a few months, there is a 2° eruption, where sores will appear on hands, legs, etc. -->contagious during these 2° periods, being most contagious during the 1° stage, & becomes harder & harder to treat the longer it is spreading throughout the body (& taking up residence in diff. types of tissues) 4) 3° stage occurs after yrs of life w the dormant Syphilis bacteria growing inside the person, especially in their nervous tissue. --> The person infected will develop lesions on infected tissue(nervous tissues usually), which can cause blindness & neurodegenerative disorders
The most common STD overall is
HPV (Human Papilloma Virus), which is the leading cause of cervical cancer
Where is IgA found? Secreted? -What group is the most common target for IgA
IgA is found in the large intestine lumen - it is secreted across the epithelial cells into the lumen of the large intestine *What group is the most common target for IgA - Gram-positive bacteria (such as Firmicutes)
one of the major problems with gonorrhea in the US?
Neisseria gonorrhoeae cases that are antibiotic resistant (slightly over a quarter of all strains were antibiotic resistant to at least one antibiotic - three quarters were susceptible to all antibiotics) -Around 10-15% of the strains were resistant to two or more antibiotics -This is one of the major problems with gonorrhea - it is becoming harder to treat (because of the spread of antibiotic resistance that is occurring)
affinity of Spirochaetes
Spirochaetes have an affinity for different types of tissue, and one of those is often nervous tissue
opportunistic pathogen -What is it? -What is it dependent on?
a bacteria that is normally commensal with you, but if your immune system becomes compromised or weakened, it will take advantage of the situation (this is relatively common) -there are often a lot of different strains, some of which are more virulent than others -dependent on both the strength of your immune system and the virulence of the particular organism
Trichomoniasis is what kind of disease?
a protozoan disease (STD)
Where is Streptococcus especially common?
common in breaks of the skin (including bug bites)
What is special (a physical characteristic of) the phylum Chlamydiae
generally lack peptidoglycan completely
Chlamydiae -How do they reproduce in humans? -What kinds of relationships do they have with other organisms? -->What has occurred as a result of this type of relationship?
group of obligate intracellular parasites (That only grow in bigger, eukaryotic cells) -In humans, they grow & reproduce by binary fission in cells that get infected until the cell lyses -can be symbiotic in other cases (species of Chlamydiae can associate w protozoa or other animals & just coexist - not so much for humans) -Bc of this lifestyle they've adopted of being intracellular parasites, they've lost a lot of genes for peptidoglycan, core metabolic processes & thus rely on host cells for a lot of the metabolites (a.a.s, etc.) -goes for the entire phylum - they all have small genomes (bc they're obligate intracellular parasites or symbionts)
What is the main bacterial strain that is adapted to llive on the skin? -What is characteristic about ot?
includes Propionibacterium, Staphylococcus, Corynebacterium, etc. (these are some of the normal residents of skin on the different parts of our body) -Staphylococcus is the only one on our taxa list (the only one we really need to know), but all of them are gram-positive bacteria
MRSA -What is it and why is it scary?
is Methicillin-Resistant Staph aureus -Methicillin is one of the last resort antibiotics (not very frequently used antibiotic, held in reserve) -If you have a bad infect, they may prescribe this -MRSA strains are scary bc they are resistant to this antibiotic as well as other antibiotics (infection can spread rather uncontrollably) -MRSA describes essentially a phenotype of the strains of Staph
Mycoplasma also lack ....... and cause a common form of what?
lack peptidoglycan - they cause a form of pneumonia
Staphylococcus -Staph. aureus --> Where found? --> how is it different than Staph. epidermidis?
normal inhabitant of the skin, but more aggressive (than Staph. epidermidis) in forming infections as well -Certain strains of Staph. aureus are more virulent than others, and if they introduced to the wrong spot on your body, they can cause major problems
Dermis, blood, and muscle tissue are all sterile due to...
protection by the skin and immune system (not exposed to the external environment, unlike the large intestine, which is essentially the "outside environment that is actually inside of us")