Term
| Describe the bacteriology of the Bacillus species |
|
Definition
| Includes man aerobic, faculative, spore forming species as gram-positive rods, widespread, some strains are motile, characteristically form spores which are heat-resistant, grows on ordinary media in an aerobic condition |
|
|
Term
| Describe the bacteriology of Bacillus anthracis |
|
Definition
| Forms very long chains of rods, non-motile, forms non-hemolytic colonies, has D-glutamic acid polypeptide capsule of a single intigenic type that is antiphagocytic, produces potent exotoxin complex with different activities |
|
|
Term
| How does B. anthracis appear after gram-staining? |
|
Definition
| Has characteristic squared ends, endospores are ellipsoidal shaped and located centrally in the sporangium, spores are highly refractile to light and resist staining |
|
|
Term
| How do colonies of B. anthracis appear on a culture plate? |
|
Definition
| Forms characteristic colony with rough, uneven surface and multiple curled extensions at the edge resembling a "medusa head" |
|
|
Term
| How do you make mucoid colonies of B. anthracis? |
|
Definition
| Incubate at an increased CO2 tension which greatly enhances production of the poly-D-glutamyl capsule |
|
|
Term
| Describe the epidemiology of B. anthracis |
|
Definition
| Primarily a disease of herbivores (farm animals), humans become infected with inhalation or ingestion of spores, infection rate is low |
|
|
Term
| Describe the pathogenicity of Bacillus anthracis |
|
Definition
| 2 major determinants of virulence: formation of a poly-D-glutamyl capsule which mediates the invasive stage of the infection and the production of a multicomponent anthrax toxin which mediates the toxigenic stage |
|
|
Term
| What is significant about the poly-D-glutamyl capsule formed by Bacillus anthracis? |
|
Definition
| All virulent strains form this capsule, depends on the plasmid px02, capsule inhibits phagocytosis and allows the organism to sruvive and grow to produce exotoxins to cause disease |
|
|
Term
| What mediates the production of anthrax exotoxin? |
|
Definition
| Temperature sensitive plasmid pX01 |
|
|
Term
| What are the different factors of the anthrax exotoxin? |
|
Definition
| Factor I = edema factor, Factor II = protective antigen, Factor III = lethal factor |
|
|
Term
| What is the most common form of anthrax? |
|
Definition
| Cutaneous anthrax, usually acquired via injured skin or mucous membrane, disease of frequently fatal if it enters the blood stream |
|
|
Term
| Describe the clinical conditions of pulmonary/inhalation anthrax (woolsorter's disease) |
|
Definition
| Results most commonly from inhalation of spores, disease begins abruptly with high fever and chest pain, progresses rapidly to a systemic hemorrhagic pathology and is often fatal if treatment cannot stop the invasive aspect of infection |
|
|
Term
| Describe the clinical conditions caused by gastrointestinal anthrax |
|
Definition
| Results from ingestion of poorly cooked meat from infected animals, is rare but may cause explosive outbreaks associated with ingestion of infected animals, extremely high mortality rate |
|
|
Term
| How is B. anrthacis diagnosed? |
|
Definition
| Isolated in sputum specimen, grows easily on regular medium with characteristic colony, hemolysis and motility exclude B. anthracis, blood cultures are positive in most cases of pulmonary anthrax |
|
|
Term
| Describe anrthrax immunity |
|
Definition
| Specific mechanism unknown, evidence favors antibody directed against toxin complex, permanent immunity requires antibody response against both capsular antigen and toxins |
|
|
Term
|
Definition
| Vaccine is available but requires yearly boosters, treated with penicillin, resistant strains treated with doxycycline or fluoroquinolone |
|
|
Term
| What causes Pneumonic plague? |
|
Definition
|
|
Term
| Describe the bacteriology of Yersinia |
|
Definition
| Animal pathogen that occasionally transmits to humans by rat fleas, gram-negative bacteria which tends to be cocobacillary, bipolar staining, Y. enterocolitica and Y. pseudotuberculosis cause GI tract disease, is a faculative anaerobe, oxidase negative, susceptible to drying, has lipid A endotoxin |
|
|
Term
| Describe the virulence of Yersinia |
|
Definition
| Virulent plasmid, outer membrane protein (Yop) is major virulent factor by inhibiting phagocytosis, predominantly by altering cytoskeletal organization of the phagocytes (impairs phagocytic movement), impairs production of inflammatory cytokines and platelet aggregation |
|
|
Term
| How does Y. pestis appear after Wayson staining? |
|
Definition
| Has a safety pin appearance |
|
|
Term
| How is Y. pestis usually grown? |
|
Definition
| On sheep blood agar but can also be grown on nutrient agar or brain-hear infusion medium, colonies appear as grey-white translucent colonies too small to be seen individually until around 48 hrs, have raised "fried egg" appearance, sometimes described as "hammered copper" |
|
|
Term
| Describe the epidemiology of plague |
|
Definition
| Sylvatic cycle still persists (includes prairie dogs, deer mice, rabbits, and wood rats), around 15 cases reported annually, virulent factors are produced at ambient temps, enhances multiplication, flea regurgitates blood and bacteria into bite wound, after enting blood, temp and ionic change causes bacteria to produce a new set of virulence factor, muliplies rapidly in lymph nodes, produces hemorhagic supprative lymphadenitis (the bubo), seeding of lungs can produce necrotizing, hemorrhagic pneumonia, and pneumonic plague |
|
|
Term
| What are the new virulence factors produced when Y. pestis enters a new host? |
|
Definition
| Yops, plasmid encoding for the secretion apparatus, PAI, F1 capsular protein (gel0like capsule with antiphagocytic property), and plasminogen activating protein |
|
|
Term
| What are the clinical features of Y. pestis? |
|
Definition
| Incubation period is 2-7 days for bubonic plague, 2-3 days for pneumonic plague, prognosis is grave if treatment is delayed by just one day |
|
|
Term
| What are the symptoms of primary pneumonic plague? |
|
Definition
| Fever, malaise, tightness of chest, cough, productive sputum, dyspnea, cyanosis |
|
|
Term
| Describe immunity to bubonic plague |
|
Definition
| Recovery convers lasting immunity via antibody against F1 capsular protein which enhances phagocytosis |
|
|
Term
| How is Y. pestis treated? |
|
Definition
| Streptomycin, can also be treated with tetracycline, chlorapmphenicol, and TSX, timely treatment is critical |
|
|
