Medically Important Bacteria

Question 1

Endospores

Answer 1

Bacillus and Clostridium can form endopsores and allow individual cells to survive until conditions improve and favor reproduction via binary fission again

Question 2

Phases of bacteria growth

Answer 2

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

Question 3

Thioglycate Medium

Answer 3

grows anaerobes

Question 4

Loffler’s coagulated serum Medium

Answer 4

Selective for corynebacterium

Question 5

Tellurite Agar

Answer 5

Differential for corynebacterium

Question 6

Hektoen enterig agar

Answer 6

differential for enteric pathogens

Question 7

Xylose-lysine-deoxycholate agar

Answer 7

enteric pathogens

Question 8

Eosin methylene blue

Answer 8

differential for enteric bacteria

E. coli will turn a metallic green

Question 9

MacConkeys

Answer 9

differntiate enteric bacteria

lactose fermenters will turn pink

Question 10

TCBS = thiosulfate citrate bile salts sucrose agar)

Answer 10

selective for Vibrio cholerae

sucrose fermenters will turn orange

Question 11

Charcoal yeast extract agar (CYE)

Answer 11

selective for legionella

Question 12

Lownstein Jensen Medium

Answer 12

selective Myobacterium

Question 13

Chocolate Agae

Answer 13

Neisseria from normally sterile sites of haemophilus

Question 14

Thayer Martin Selective medium

Answer 14

chocolate agar with vanco, nystatin, and colistin to kill normal flora and NONPATHOGENIC neisseria
Selective for neisseria from sites with normal flora

Question 15

Mnemonic for bacteria that need cysteine to grow

Answer 15

the fours sisters "Ella" worship in the "Cysteine" chapel
Francisella,
brucella
legionella
pasteurella

Question 16

Obligate Aerobes

Answer 16

Mycobacterium = TB at apex of lung
Pseudomonas = unusual UTI that "cannot ferment"

Question 17

Microaerophilic

Answer 17

low 02. campylobacter and heliobacter

Obligate anaerobes

Question 18

Obligate Anaerobes

Answer 18

lack superoxide dismutase and usually catalase
Actinomyces
bacteriodes
clostridium

Question 19

Staphylococcus Aureus 
Labs
Reservoir
Transmission
Predisposing factors
Pathogenesis
Major Diseases

Answer 19

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)

Question 20

Staphylococcus Epidermidis

Answer 20

Gram (+) cocci, catalse (+), coagulase (-), novobiocin (S)

infections of catheters/shunts

Question 21

Staphylococcus Saprophyticus

Answer 21

Gram (+) cocci, catalse (+), coagulase (-), novobiocin (R)

Honeymoon cystitis = UTI in newly sexually active female

Question 22

Treatment of Staphylococcus

Answer 22

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

Question 23

Streptococcus Pyogenes 
Labs 
Reservoir
Pathogenesis
Major Diseases
Treatment

Answer 23

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

Question 24

Streptococcus Agalactiae
Labs 
Reservoir
Pathogenesis
Major Diseases
Treatment

Answer 24

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