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30 Cards in this Set
- Front
- Back
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Genus Bacillus characteristics
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gram-positive
endospore motile rods aerobic catalase positive primary habitat soil |
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Bacillus anthracis
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virulence factors: capsule and exotoxins
3 types: cutaneous, pulmonary, gastrointestinal treated with penicillin or tetracycline Biological warfare threat 2001 Dead live stock decontaminated before burial to prevent soil contamination |
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Bacillus cereus
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airborne and dustborne
grows in foods, spores survive cooking ingestion of toxin-containing food causes nausea, vomiting, abdominal cramps, and diarrhea for 24 hours no treatment spores abundant in environment |
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Genus Clostridium characteristics
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gram-positive spore-forming rods
anaerobic and catalase negative 120 species spores produced only under anaerobic conditions synthesize organic acids and alcohols cause wound and tissue infections and food intoxications |
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Clostridium perfringens
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causes gas gangrene
2nd most common cause of food poisoning several virulence factors (toxins, collagenase, hyaluronidase, and DNase) |
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Clostridium difficile
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normal resident of colong, low in numbers
causes ANTIBIOTIC-ASSOCIATED COLITIS treatment with broad-spec antiobiotics kills the other bacteria, allowing C. difficile to grow produces enterotoxins that damage intestine major cause of diarrhea in hospitals |
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Clostridium tetani
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common resident of soil & GI tracts of animals
causes tetanus or lockjaw spores usually enter through accidental puncture wounds, burns, umbilical stumps, frostbite, and crushed body parts tetanospasmin neurotoxin causes paralysis vaccine booster every 10 years |
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Clostridium botulinum
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Food poisoning: spores are in soil, may contaminate vegetables, improper canning does not kill spores, they germinate in the can and produce botulinum toxin which causes paralysis by preventing release of acetylcholine
infant botulism: caused by ingested spores that germinate in the body and release toxin wound botulism: spores enter wound and cause food poisoning symptoms |
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Lysteria monocytogenes
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non-spore forming gram-positive
coccobacilli to long filaments 1-4 flagella, no capsules resistant to cold, heat, salt, pH extremes and bile primary reservoir in soil and water can contaminate foods and grow during refrigeration most cases are from contaminated diary products, poultry and meat disease is often mild/subclinical (fever, diarrhea) listerosis in immunocompromised patients, fetuses, and neonates affects brain and meninges (20% death rate) ampicillin & trimethoprimsulfamethoxazole prevention: pasteurization and cooking |
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Erysipelithrix rhusiopathiae
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gram-positive rod widely distributed in animals and environment
primary reservoir: tonsils of healthy pigs enters through skin abrasion, multiplies to produce erysipeloid, dark red lesions treated with penicillin or erythromycin vaccine for pigs |
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Corynbacterium diptheriae
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gram-positive irregular bacilli
catalase positive possess mycolic acids and a uniquie type of peptidoglycan 2 stages of disease: local infection (upper respiratory tract) and diptherotoxin production and toxemia pseudomembrane formation can cause asphyxiation diptheria: most cases are in children aged 1-10 in crowded settings, vaccine readily available |
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Propionibacterium acnes
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gram-positive rods
aerotolerant or anaerobic non-toxigenic common resident of sebaceous glands: causes acne |
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Genus Mycobacteria characteristics
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gram-positive irregular bacilli
acid-fast staining strict aerobes, catalase positive prsses mycolic acid and a unique type of peptidoglycan do not form capsules, flagella or spores grow slowly |
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Mycobacterium tuberculosis
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contain complex waxes and other substances that prevent destruction by lysosomes or macrophages
transmitted by airborne respiratory droplets only 5% of infected people develop clinical disease diagnosis: tuberculin testing, x rays, direct identification of acid-fast bacilli in specimen, and cultural isolation and biochemical testing treatment: 6-24 months of at least 2 drugs from a list of 11, vaccine success rate 80% in children, 20-50% in adults |
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Mycobacterium leprae
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Hansen's bacillus
strict parasite: has not been grown on artificial media or tissue culture slowest growing of all species multiplies with host cells in large packets called globi causes leprosy (chronic disease that begins in the skin and mucous membranes and progresses into nerves) endemic regions throughout the world spread through direct inoculation from leprotics 2 forms: tuberculoid and lepromatous treatment by long-term combined therapy |
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Actinomycetes
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genera Actinomyces and Nocardia are nonmotile filamentous bacteria related to mycobacteria
may cause chronic infection of the skin and soft tissues Actinomycetes species is responsible for diseases of the oral cavity and intestines Nocardia brasiliensis causes pulmonary disease similar to TB |
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Genus Staphylococci characteristics
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spherical cells arranged in clusters
gram-positive common inhabitant of the skin and mucous membranes lack spores and flagella may have capsules numerous species |
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Staphylcoccus aureus
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grows in large, round, opaque colonies
optimum temperature of 37C present in most environments frequented by humans readily isolated from fomites carriage rate for healthy adults i 20-60% carriage is most in anterior nares, skin, nasopharynx, intestine facultative anaerobe withstands high salt, extremes in pH, and high temperatures produces many virulence factors Enymes: coagulase, hyaluronidase, staphylokinase, DNase, lipases, penicillinase Toxins: hemolysins, leukocidin, enterotoxins, exfoliative toxin, toxic shock syndrome toxin Disease: localized (abscess, folliculitis, furuncle, carbuncle, inpetigo), systemic (osteomyelitis, bacteremia) toxigenic disease (food intoxication, scalded skin syndrome, toxic shock syndrome) |
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Staphylcoccus epidermidis
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lives on skin and mucous membranes and causes endocarditis, bacteremia, and UTI
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Staphlycoccus hominis
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lives around apocine sweat glands
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Staphlycoccus capitis
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lives on scalp, face, and external ear
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Staphlycoccus saprophyticus
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infrequently lives on skin, intestine, vagina and causes UTI
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Genus Streptococci characteristics
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gram-positive spherical/ovoid cocci arranged in long chains
non-spore forming, non-motile can form capsules and slime layers facultative anaerobes catalase negative, peroxidase positive most parasitic forms are fastidious and require enriched media small, nonpigmented colonies sensitive to dryin , heat, and disinfectants numerous species |
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Streptococci classification
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Lancefield classification system: based on cell wall (a, b, c...)
another classification based on hemolysis reactions b-hemolysis - A, B, C, G, & some D a-hemolysis - S. pheumoniae and others collectively called viridans |
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beta-hemolytic Streptococcus pyogenes
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group A, most serious streptococcal pathogen
strict parasite: inhabits throat, nasopharynx, and occasionally skin produced C-carbohydrates, M-protein (fimbrae), streptokinase, hyaluronidase, DNase, hemolysins, pyogenic toxin Humans only reservoir transmission through contact, droplets, food, fomites skin infections: pyoderma, impetigo, erysipelas systemic infections: strep throat, pharyngitis, scarlet fever sequelae: rheumatic fever, glomerulonephritis toxic sequelae to strep throat |
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Streptococcus agalactiae
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regularly resides in human vagina, pharynx, and large intestine
can be transferred to infant during delivery and cause sever infection most prevalent cause of neonatal pneumonia, sepsis, and meningitis 15,000 infections and 5,000 deaths in US pregnant women should be screened and treated wound and skin infections and endocarditis in debilitated people |
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Enterococcus faecalis
Enterococcus faecium |
normal colonists of human large intestine
cause opportunistic urinary, wound, and skin infections, particularly in debilitated people enterococcus genus related to streptococci and so studied together |
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Viridans group
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a-hemolytic, large complex group
most numerous and widespread residents of the oral cavity and also found in nasopharynx, genital tract, and skin not very invasive but dental or surgical procedures facilitate entrance bacteremia, meningitis, abdominal infection, tooth abscesses most serious infection: subacute endocarditis (blood-borne bacteria settle and grow on heat lining or valves persons with preexisting heart disease are at high risk and receive prophylactic antibiotics before surgery or dental procedures |
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Streptococcus mutans
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produces slime layers that adhere to teeth, basis for plaque involved in dental caries (cavities)
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Streptococcus pneumoniae
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causes 60-70% of all bacterial pneumonias
arranged in pairs and short chains culture requires blood or chocolate agar growth improved by 5-10% CO2 lack catalase and peroxidase (cultures dies in O2) all pathogenic strains form large capsules (major virulence factor) causes pneumonia and otitis media vaccine available for high risk people 5-50% of all people carry it as normal flora in pharynx very delicate, doesn't survive long outside of its habitat pneumonia occurs when cells are aspirated into the lungs of susceptible individuals pneumoccci multiply and induce and overwhelming inflammatory response treated with penicillin |
