strep and staph

Question 1

is streptococcus gram positive or negative

Answer 1

negative

Question 2

what is the shape of streptococcus

Answer 2

cocci. in pairs or chains

Question 3

is streptococcus catalase negative or positive

Answer 3

negative

Question 4

how is streptococcus classified

Answer 4

extent of rbc haemolysis

alpha haemolytic = partial
beta haemolytic = complete
gamme haemolytic = no haemolysis

Question 5

how does alpha haemolytic streptococcus appear on blood agar

Answer 5

greenish

Question 6

how to differentiate streptococcus penumoniae from other alpha haemolytic

Answer 6

optochin test. s pneumonia optochin sensitive the rest are optochin resistant

Question 7

which streptococcus causes caries

Answer 7

s. mutans

Question 8

what gram negative bacteria can cause infective endocarditis

Answer 8

alpha haemolytic

Question 9

how does beta haemolytic streptococcus appear on blood agar

Answer 9

completely clear, translucent agar

Question 10

what group of strep are s pyogenes and s agalactiae from

Answer 10

both beta haemolytic. s pyogenes group a, s agalactiae group b

Question 11

what group is viridans streptococcus in

Answer 11

alpha haemolytic

Question 12

what does s pneumoniae cause

Answer 12

community acquired pneumonia, meningitis, respiratory tract infection

Question 13

what is characteristic of s pneumoniae on agar plate

Answer 13

draughtman’s colonies: depressed centre with elevated rim

Question 14

how to treat s pneumoniae

Answer 14

penicillin, vancomycin if penicillin allergic, cephalosporins

Question 15

what bacteria causes impetigo

Answer 15

group a (s pyogenes) beta haemolytic streptococcus and staph aureus

Question 16

what causes characteristic erythematous rash in scarlet fever

Answer 16

erythrogenic toxins eg streptolysin, leukocidin produced by s pyogenes

Question 17

who does s agalactiae affect

Answer 17

infected mother passes to baby during birth, causing neonatal meningitis, pneumonia, septicemia (prophylaxis with penicillin, amoxycillin)

Question 18

what kind of streptococcus is group d beta haemolytic

Answer 18

enterococcus

Question 19

is staphylococci gram positive or negative

Answer 19

positive

Question 20

what is the shape of staphylococci

Answer 20

cocci, in clusters like grapes

Question 21

is staphylococci aerobic

Answer 21

facultative anaerobe

Question 22

what is coagulase test used for

Answer 22

differentiate staph aureus from other commensal staphylococci. staph aureus is coagulase positive

Question 23

is s aureus sporing

Answer 23

no

Question 24

how does s aureus infect cells

Answer 24

extracellular proteins eg enzymes, toxins

Question 25

what does s aureus enterotoxin result in

Answer 25

vomiting and diarrhea, rapid onset (no need for antibiotics)

Question 26

which bacteria causes toxic shock syndrome

Answer 26

s aureus, produce toxin TST

Question 27

what bacteria has super antigen that stimulates enhanced t cell response

Answer 27

s aureus

Question 28

what do s aureus epidermolytic toxins causes

Answer 28

scalded skin syndrome

Question 29

what does localised s aureus infection cause

Answer 29

sappurative necrosis

Question 30

how to treat s aureus

Answer 30

do not use penicillin and amoxicillin. treat with cloxacillin. MRSA resistant to Cloxacillin, treated with Vancomycin if patient has penicillin allergy, give macrolides instead eg erythromycin, clarithromycin

Question 31

patient prescribed clindamycin for s aureus. experiences diarrhea. what happened

Answer 31

clostridium difficile associated diarrhea as good flora in gut cleared allowing cd to proliferate

Question 32

is coagulase negative staphylococci pathogenic

Answer 32

normal commensal bacteria, low pathogenicity. but may be able to cause low grade infections in immunocompromised

Question 33

example of coagulase negative staphylococci

Answer 33

s epidermis, s saprophyticus

Question 34

infection with honey crusted lesion caused by

Answer 34

s aureus, which can have golden appearance on agar plate. infection is impetigo

Question 35

what can cause intertrigo

Answer 35

sticky redness where skin rub together. most commonly caused by candida, can be caused by strep/staph

Question 36

tender track seen along forearm. cause?

Answer 36

lymphangitis. beta hemolytic strep or staph aureus invaded lymphatic vessel

Question 37

bilateral tender erythematous sections on face ie erysipelas caused by

Answer 37

group a strep

Question 38

what causes gas gangrene

Answer 38

mainly clostridium perfringens, but also staph and strep

Question 39

what bacteria class causes necrotising fasciitis

Answer 39

streptococci (strep mitis, beta haemolytic group a strep)

Question 40

what causes prosthetic joint infection

Answer 40

coagulase negative staph

Question 41

what causes septic arthritis

Answer 41

staph aureus

Question 42

what causes osteomyelitis

Answer 42

staph aureus typically. in <1y/o, may be due to coagulase negative staph ie skin commensals