Medically Important Bacteria Flashcards
Endospores
Bacillus and Clostridium can form endopsores and allow individual cells to survive until conditions improve and favor reproduction via binary fission again
Phases of bacteria growth
Lag = cells at begging same as cells at end. Cells jsut are adapting to the environment and turning on proteins that will help them utilize the medium
Log = rapid exponential growth (generation time = time it takes for 1 cell to divide into 2)
Stationary Phase = nutrients used up and toxic byproducts tsart to accumulate. See plateau cus # of new cells = # of dying cells
Death phase = cells begin to die and total # declines
Thioglycate Medium
grows anaerobes
Loffler’s coagulated serum Medium
Selective for corynebacterium
Tellurite Agar
Differential for corynebacterium
Hektoen enterig agar
differential for enteric pathogens
Xylose-lysine-deoxycholate agar
enteric pathogens
Eosin methylene blue
differential for enteric bacteria
E. coli will turn a metallic green
MacConkeys
differntiate enteric bacteria
lactose fermenters will turn pink
TCBS = thiosulfate citrate bile salts sucrose agar)
selective for Vibrio cholerae
sucrose fermenters will turn orange
Charcoal yeast extract agar (CYE)
selective for legionella
Lownstein Jensen Medium
selective Myobacterium
Chocolate Agae
Neisseria from normally sterile sites of haemophilus
Thayer Martin Selective medium
chocolate agar with vanco, nystatin, and colistin to kill normal flora and NONPATHOGENIC neisseria
Selective for neisseria from sites with normal flora
Mnemonic for bacteria that need cysteine to grow
the fours sisters "Ella" worship in the "Cysteine" chapel Francisella, brucella legionella pasteurella
Obligate Aerobes
Mycobacterium = TB at apex of lung Pseudomonas = unusual UTI that "cannot ferment"
Microaerophilic
low 02. campylobacter and heliobacter
Obligate anaerobes
Obligate Anaerobes
lack superoxide dismutase and usually catalase
Actinomyces
bacteriodes
clostridium
Staphylococcus Aureus Labs Reservoir Transmission Predisposing factors Pathogenesis Major Diseases
Labs
-YELLOW colonies ob blood agar
-Gram positive cocci in clusters
-Catalase (+), Coagulase (+), Beta hemolytic, and ferments manitol
Reservoir - nasal mucosa and skin
Transmission = hands/sneexing and FOODS (custard pastries, potato salad, canned meats)
Predisposing = TAMPONS/”recenet menses”/surgical packing and Chonic granulomatous disease
Pathogenesis
-TSST1 superantigen
-enterotoxins that are heat stable so survive and ingested even when heat food and kill the bacteria
-Exfolatins = skin exfoliating toxins involved in scalded skin syndrome and bullous impetigo
Major Diseases
-gastroenteritis from ingested premade toxins (2-6hrs after eating
-acute infective endocarditis
-abscesses and mastitis
-Toxic shock syndrome = TSST1 causes scarlatiniform rash that desquamates (especially of palms and soles)
- impetigo = bullous
-Pneumonia = rapid onset and high necrosis. SALMON colored sputum nosocomial, ventilator, CF, chronic granulmoatous disease
-#1 cause of OSTEOMYELITIS especially in kids (unless they have sickle cell then think salmonella)
Staphylococcus Epidermidis
Gram (+) cocci, catalse (+), coagulase (-), novobiocin (S)
infections of catheters/shunts
Staphylococcus Saprophyticus
Gram (+) cocci, catalse (+), coagulase (-), novobiocin (R)
Honeymoon cystitis = UTI in newly sexually active female
Treatment of Staphylococcus
gastroenteritis is self limiting
Nafcillin/oxacillin major drugs (methacillin class)
for MRSA give vancomyocin
for VRSA or VISA give combo therapy of quinupristin and dalfopristin
Streptococcus Pyogenes Labs Reservoir Pathogenesis Major Diseases Treatment
Group A strep
Labs = gram (+), catalase (-), beta hemolytic, bacitracin (S)
Reservoir = throat
Pathogenesis
- M protein is antiphagocytic and M12 strains can cause acute glomerulonephritis
- enzymes allow it to break down skin and blood clots so it can spread diffusely
- Exotoxins A-C are superantigens and cause fever and rash
Major Diseases
-Pharyngitis = abrupt onset with tonsilar absecesses
-Scarlet fever = blanching “sandpaper rash” (palms and soles normally spared), strawberry tongue
-Impetigo = honey crusted lesions
-cellulitis and necrotizing fasciitis
-Rheumatic fever = 2 weeks after pharyngitis have antibodies directed towards heart (type II HS) see carditis, fever and joint inflammation. ASO titer >200
- acute glomerulonephritis = immune complexes cound to glomeruli and pulmonary edema w/ hypertension (type III HS)
Treatment
-beta lactams (penicillins) or macrolides if allergic
-prophylactic antibiotic treatment for people that had rheumatic fever
Streptococcus Agalactiae Labs Reservoir Pathogenesis Major Diseases Treatment
Group B Strep
Labs = gram (+), catalase (-), beta hemolytic, bacitracin (R), CAMP test (+)
Reservoid = Vagina and GI
Pathogenesis = capsule
Major Diseases = #1 cause of neonatal meningitis and septicemia
treatment = ampicillin w/ aminoglycoside or a cephalosporin (especially if meningitis)
-prophylactically treat women during labor w/ apicillin or penacillin. Clindamycin or erythromycin if allergic
