Streptococci

Question 1

alpha hemolytic streptococci?

Answer 1

s pneumo, s mutans, and s viridans

Question 2

beta hemolytic streptococci?

Answer 2

strep pyogenes (GAS), strep agalactiae (GBS)

Question 3

gama (non hemolytic) streptococci?

Answer 3

enterococcus

Question 4

• gram positive cocci arranged in chains
• normal flora of skin and mouth
• facultative anaerobes
• catalase negative

Answer 4

streptococci

Question 5

• present in mucosal epithelium of URT or epidermis
• transmission via direct contact or respiratory droplets (sneezing and coughing)
• invades mucus membrane of new host

Answer 5

GAS S. pyogenes

Question 6

• most common bacterial infection of the throat
• organisms persist 1-4 weeks w/o treatment
• treat with penicillins

Answer 6

acute streptococcal pharyngitis

Question 7

• complication of GAS pharyngitis
• produces SpeA/SpeC exotoxins
• diffuse erythematous sandpaper rash on chest
• raw strawberry tongue, desquamation
• circumoral pallor around moth
• can lead to rheumatic fever or glomerulonephritis

Answer 7

scarlet fever

Question 8

skin infections of group A strep pyogenes?

Answer 8

• impetigo: young kids 2-5
• erysipelas: raised bright red plaques with sharply defined borders
• wound infections, cellulitis
• toxic shock syndrome and necrotizing fasciitis

Question 9

Group A strep pyogenes virulence factors?

Answer 9

• M protein
• hyaluronic acid capsule (non antigenic)
• streptolysin O: pore forming toxin, lyses target cells
• Spe: superantigen causes scarlet fever and toxic shock syndrome
• streptokinases

Question 10

drug of choice for strep throat?

Answer 10

amoxacillin

Question 11

drug of choice for GAS strep pyogenes cellulitis?

Answer 11

penicillin, ceftriaxone

Question 12

drug of choice for bacteremia/toxic shock syndrome due to GAS strep pyogenes?

Answer 12

penicillin + clindamycin (suppresses toxin production)

Question 13

diagnosis of strep throat?

Answer 13

RADT of group A capsule antigen, culture if negative for more sensitivity

Question 14

• encapsulated
• group B antigen
• Beta hemolytic, weakly
• colonization of GI and GU tracts

Answer 14

GBS s. agalactiae

Question 15

• person to person transmission
• bacteremia, skin and soft tissue infections, pneumonia, endocarditis
• risk factors: diabetes, cancer, kidney disease, advanced age

Answer 15

GBS disease in adults

Question 16

• normal vaginal flora

- prenatal screening cultures at 35-37 WGA

Answer 16

GBS

Question 17

• pneumonia, meningitis, sepsis
• risk factors: maternal colonization, premature rupture of membranes
• early onset or late onset

Answer 17

GBS disease in neonates

Question 18

GBS virulence factors?

Answer 18

polysaccharide capsule, adhesins, c5a peptidase inhibits neutrophils, beta hemolysin, CAMP factor

Question 19

drug of choice for group B strep meningitis/bacteremia?

Answer 19

penicillin G

Question 20

drug of choice for GBS endocarditis?

Answer 20

penicillin G + gentamycin

Question 21

DOC for GBS neonates?

Answer 21

ampicillin + gentamycin

Question 22

• alpha hemolytic
• commensal and opportunistic pathogen (subacute endocarditis, intra abdominal abscesses, dental caries)
• bind fibrin platelet aggregates at damaged heart valves
• resistant to optochin and bile insoluble

Answer 22

strep viridans

Question 23

• gram positive lancet shaped coccus growing in pairs or short chains
• carbohydrate capsule
• naturally competent for DNA transformation
• transmission via respiratory droplets
• bacteremia higher in African Americans and native Americans

Answer 23

strep pneumonia

Question 24

• most common cause of CAP
• common cause of sinusitis and otitis media
• can develop into meningitis in children
• respiratory viral infection a predisposing factor

Answer 24

strep pneumonia

Question 25

- aspiration of bacteria and replication in alveolar spaces - 1-30 day incubation - abrupt onset of fever and shaking chills - pleurisy, productive cough, blood tinged sputum - bactermia

Answer 25

pneumonia

Question 26

risk factors for pneumonia?

Answer 26

antecedent viral infection (esp influenze), smoking, age less than 2 or greater than 65, hematologic disorders, asplenia, COPD, diabetes

Question 27

atypical walking pneumonia?

Answer 27

slow onset, moderate fever, non productive cough

Question 28

strep pneumonia virulence factors?

Answer 28

polysaccharide capsule, C polysaccharide present in urine and serum

Question 29

strep pneumonia toxins?

Answer 29

pneumolysin toxic to bronchial epithelial cells, autolysin degades peptidoglycan, IgA protease

Question 30

lab diagnosis of strep pneumonia?

Answer 30

- lancet shaped gram (+) diplococci - bile soluble, optochin sensitive (Kirby Bauer testing) - Quellung reaction visualizes capsule - C polysaccharide: capsular anitgen detected in CSF or urine

Question 31

treatment of strep pneumo?

Answer 31

- penicillin - vancomycin - fluoroquinolone + 3rd gen cephalopsorin (tax, tri, taz)

Question 32

strep pneumo prevention?

Answer 32

- Pneumovax PPSV23: adults >65, chronically ill, immunocompromised - PCV7 prevnar, PCV13

Question 33

- E faecalis and E faecium most common - cell wall modification to D-lactate - group D streptococcus

Answer 33

enterococcus

Question 34

- opportunistic pathogen - subacute endocarditis - biliary tract infections, UTIs

Answer 34

enterococcus

Question 35

enteroccocus virulence: - growth in 6.5% _____ or 40% _____ - high level antibiotic resistance often encoded on ________

Answer 35

NaCl, bile salts conjugative plasmids

Question 36

enterococcus lab tests?

Answer 36

- non hemolytic, grows in presence of high salt and bile salts - positive reaction with group D antisera

Question 37

enterococcus treatment?

Answer 37

penicillin, vancomycin, or ampicillin + beta lactamase inhibitor