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Microbiolgy Lect 5
Bacillus, Clostridium, and other Gram Positive Rods
| Question | Answer |
|---|---|
| Describe the virulence factors and generalities about Bacillus | -small gram positive rod -toxin mediated -virulence factors: endospores and enterotoxins |
| Bacillus anthracis: where it's found; who is affected; it's 3 clinical presentations | -etiologic agent of anthrax; typically affects herbivores; spore formers that stay in the soil -Those who come into contact with the infected animals (farmers) -3 clinical presentations: develop cutaneous eschars; gastroenteritis; terrorism via inhalati |
| Bacillus cereus: what are it's 2 clinical presentations? | -Gastroenteritis: mediated by enterotoxins -Ocular: traumatic implantation of spores in the eye (causes rapid, progressive destruction) |
| Describe the virulence factors and generalities about Corynebacterium | -irregularly shaped gram positive rods -Ubiquitous in plants and animals; they colonize on human skin, GI, GU (genito-urinary), and respiratory tracts -collectively known as "diphtheroids" |
| What organism causes diphtheria? | C. diphtheriae |
| Describe the morphology of Erysipelothrix. Where is it found and how is it transmitted? | -small, thin rods that form long filaments -not found clinically but is found widespread in animals (turkey, swine and fish) -it is transmitted from animals to humans -affects butchers, farmers, and veterinarians -causes endocarditis and skin infection |
| Describe the morphology of Listeria. | -small, paired coccobacilli |
| Describe the generalities about Listeria monocytogenes. | -Widely found in animals, soil, water, and vegetation -Transmitted in contaminated food (especially unpasturized milk); vertically; zoonotic -fecally carried asymptomatic state -very young, very old and immunocompromised are affected -STRICT PATHOGEN |
| what are the virulence factors of Listeria monocytogenes? | -hemolysin; listeriolysin O, and they have th ability to survive in cold temperatures **Hemolysin and listeriolysin O abilities allow the organism to navigate host tissues** |
| Describe the generalities about Actinomyces. What are it's virulence factors. | -strict anaerobe that has a filamentous morphology (resembles hyphae) -colonize upper respiratory, GI, and female genital tracts (cause "lumpy jaw" cervix) -Low virulence factors: causes infection when mucus membranes are breached; present as lesions |
| What is the most common Actinomyces (anaerobe) species that causes human infections? | A. israelii |
| Describe the generalities for Clostridium. | -gram positive spore forming rods -found in the soil, water, and human GI tract |
| Describe the generalities and virulence factors for Clostridium perfringens. | -DOES NOT FORM SPORES -wide disease spectrum from mild gastroenteritis to severe myonecrosis -Serotypes A-E are antigen specific -virulence factors: arsenal of toxins known as "lethal toxins" |
| Which type of C. perfringens is responsible for most human disease? What type of toxin does it produce? | Serotype A: produces alpha toxin; it lyses red, white, platelet, and endothelial cells. |
| What are the generalities and virulence factors for Clostridium tetani? | -forms spores -other virulence factors: hemolysin; neurotoxin (responsible for clinical expression of tetanus by blocking NT release-what causes painful contortions) -up to 50% of deaths are in newborns; tetanus does not occur very often in dev. countri |
| Describe the generalities and virulence factors for Clostridium botulinum. | -causes botulism -found in soil -mediated by neurotoxin (types A-G are antigenically distinct) -very potent! Usually starts off as GI illness and then affects the cranial nerves |
| What are the 3 presentations of botulism? | -Food borne -Infant botulism: results from giving children under 1 y.o honey; the spore is activated when ingested and organism secretes EXOTOXIN -wound botulism; very rare |
| Describe the generalities and virulence factors for Clostridium difficile. | -normal GI in flora; disrupted by antibiotics -virulence factors: secrete toxin A (enterotoxin) and toxin B (cytotoxin); also form spores (helps it survive in hospital environments) -very strict anaerobe |
| What is an enterotoxin? | It is a chemotactic factor; it causes neutrophils to migrate to the GI tract. This increases permeability in the GI tract. |
| What is C. difficile most famous for causing? | AAC: antibiotic associated colitis -when people take antibiotics, it wipes out this normal flora so when they are reintroduced to C. difficile, it becomes very pathogenic and makes them very ill. |
| Describe the generalities of Lactobacillus. | -normal flora of the mouth, GI, and GU tract -organisms are often found as contaminants in urine -Cause: transient bacteremia ( after birth or gyn procedure); endocarditis; and opportunistic septicemia |
| Describe the generalities of Mobiluncus and Gardnerella | Appear gram negative on stains, but are classified as gram positive because they have a gram positive cell wall, antibiotic susceptibility, and lack endotoxin -colonize female genital tract -in post menopausal women, this infection can present as a UTI |
| Describe the generalities of Propionibacterium | -small, coccobacilli anaerobes -normal flora of skin, oropharynx, and female genital tract (they are found in the sebaceous glands and attract neutrophils to the site where you get pustules) -Most medically important species: P. acnes |
| What are the 5 medically important ANAEROBIC gram positive rods? | 1. Actinomyces 2. Clostridium 3. Lactobacillus 4. Mobiluncus 5. Propionbaacterium **colonize skin and mucosal surfaces** |
| What are the 4 medically important AEROBIC gram positive rods? | 1. Bacillus 2. Corynebacterium 3. Erysipelothrix 4. Gardnerella |
Created by:
mlb63
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