Gram Positive Cocci

Question 1

Staph common infections

Answer 1

wound (boils, carbunles, impetigo)
septicemia
UTI
pneumonia

Question 2

Staph virulence factors

Answer 2

toxins (enterotoxins, toxic shock syn., exfoliative toxin, cytolytic toxin)
enzymes (coagulase, protease, hyaluronidase, lipase)
Protein A (interferes w/ opsonization by binding Fc or immunoglobins)

Question 3

complications of Staph aureus toxins

Answer 3

enterotoxin A & B- food poisoning
Toxin 1- toxic shock syn., Super Antigen, and Cytokine release (IL-1, 2, 6; TNF)
exfoliative toxin- scalded skin syn. (infants)

Question 4

Toxic shock syn.

Answer 4

high fever, hypotension, shock, rash

TSST-1 (acts on vascular sys. causing inflam., fever, shock)``

Question 5

Staph. aureus identifying features

Answer 5

catalase +
uniform in size
coagulase positive
beta hemolytic
ferments mannitol
creamy buttery colony
DNAse +

Question 6

other coagulase negative Staph

Answer 6

S. epidermidis (UTI)
S. haemolyticus (wounds, UTI, endocarditis)
S. saphrophyticus (UTI)
S. lugdunensis (endocarditis, meningitis, joint infec., surgical wound infec.)
S. warneri/ S. capitis/S. simulans/S. schleiferi (endocarditis, wound infec., septicemia)

Question 7

Staph key test

Answer 7

catalase test (+ bubbles)
glucose fermentation (+ yellow)
Staph aureus vs. CNS= coagulase test

Question 8

Micrococcus

Answer 8

GPC in tetrads
M. luteus bright yellow-orange
oxidase +
bacitracin S
furazolindone R
lysostaphin R

Question 9

Streptococcus grouping

Answer 9

Lancefield: ABCDFG

non-lancefield: viridans, pneumoniae

Question 10

GAS (group a strep)

Answer 10

chains or pairs; very tiny
S. pyogenes
capsule
beta hemolytic
bacitracin A: S
pharyngitis, impetigo, pneumonia, wound infec.
PYR +

Question 11

GBS (group b strep) characteristics

Answer 11

chains, pairs
S. agalactiae
beta hemolytic
neonatal meningitis
CAMP test + (arrow head hemolysis)
Na hippurate +

Question 12

Group C, F, G strep

Answer 12

C, G beta hemolytic
C, G cause human disease
pharyngitis
normal oral, GI and vaginal flora

Question 13

group D strep & Enterococcus

Answer 13

D carbo in wall
grp D: bile esculin + , no growth 6.5%NaCl, PYR -
Entero: bile esculin +, grow in 6.5% NaCl, PYR +
alpha/gamma hemolysis

Question 14

Step pneumoniae

Answer 14

GPC pairs, lancet shaped
capsule
alpha hemolytic
optochin S
Na deoxycholate +

Question 15

viridans Strep

Answer 15

oral, vaginal, GI normal flora
endocarditis, meningitis, dental caries
6 grps
small cocci may b in chains

Question 16

other strep like orgainisms

Answer 16

Aerococcus, Gemella, Leuconostoc
rarely cause infec.
facultative anaerobes
A. viridans & A. urinae clusters and tetrads
viridans alpha hemo., PYR +, LAP -
urinae alpha hemo., PYR -, LAP +
Gemella catalase -, PYR -, LAP +, vancomycin R

Question 17

S. epidermidis

Answer 17

Normal skin flora

Path: community acquired infec/contamination, prostectic valve endocarditis, septicemia in immonocompromised

Question 18

S. saprophyticus causes…

Answer 18

UTIs

Question 19

S. lugdensis

Answer 19

Community/hospital acquired infec.
Most virulent contain mecA gene which codes oxacillin resistance
Endocarditis has high mortality rate

Question 20

MRSA

Answer 20

Methicillin resistant staph aureus

Resistant to penicillin, oxacillin, and nafacilin

Question 21

CA-MRSA

Answer 21

Community associated methicillin resistant staph aureus

Question 22

VRSA

Answer 22

Vancomycin resistant staph aureus

Question 23

Streptococcaceae

Answer 23

Streptococcus and Enterococcus
Negative catalase
Aerotolerant anaerobes
Capnoplilic

Question 24

Capnophilic

Answer 24

Require increased CO2 to grow

Question 25

Strep etc. Exotoxins

Answer 25

Hemolysins alpha and beta

Question 26

Pyogenic Strep

Answer 26

``` (pus forming) S. pyogenes S. agalctaie S. dysgalactaie subsp. equisimilis S. anginosus ```

Question 27

GAS infections

Answer 27

``` Bacterial pharyngitis Impetigo, cellulitis, scarlet fever Necrotizing fasciitis Toxic shock syndrome Post streptococcal sequelae ```

Question 28

Complications of GAS

Answer 28

Rheumatic fever | Acute glomerulonephritis

Question 29

Strep agalctiae

Answer 29

GBS Capsule GBS disease

Question 30

GBS disease

Answer 30

Neonatal Early onset: under 7 days old- vertical transmission, 80% of cases, mortality rate high Late onset: 1wk-3mons after birth, meningitis, not usually vertical transmission

Question 31

Group c and d strep

Answer 31

Beta hemolytic S. dysgalactaie subsp equisimilis (large colony) S. anginosus (small colony) S. equi subsp zooepidemicus (rare in humans- animal pathogen)

Question 32

S. pneumoniae infections

Answer 32

Pneumonia, sinusitis, otitis media in kids <3, bacteremia, meningitis Spread through respiratory droplets Secondary infec.

Question 33

S. pneumoniae vaccine

Answer 33

``` Pneumococcal vaccine (pcv): 13 serotypes used- polysaccharides conj. to diltheria {children starting at 2 mons} PPSV23- 23 polysaccharides {adults 65+} ```

Question 34

S. pneumoniae morphology

Answer 34

``` gpc in pairs More oval lancet shaped Checked shaped colonies on plates Alpha hemolytic Auto lyses so hard to keep alive Optochin (S) & bile solubility (+) key tests ```

Question 35

S. agalctiae morphology

Answer 35

Greyish white colonies on plates Beta hemolytic CAMP and hippurate useful tests

Question 36

S. pyogenes morphology

Answer 36

Small transparent colonies Beta hemolytic GPC in short chains Bacitracin (S) and PYR (+) key tests

Question 37

Viridians Streptococci

Answer 37

``` Normal Flora of resp.tract/female genital tract/GI tract S. mitis grp S. mutans grp S. salivarius grp S. bovis grp S. anginosus grp ```

Question 38

Viridans Streptococci morphology

Answer 38

Viridans (green)- alpha hemolytic mostly Fastidious Pyr (-), lap (+) key tests Look like strep on plates

Question 39

Enterococcus

Answer 39

Normal Flora intestinal tract E. faecalis E. faecium

Question 40

Enterococcus infection

Answer 40

Noscomial infections: UTI Bacteremia

Question 41

VRE

Answer 41

Vancomycin resistant Enterococcus Resistance to aminoglycosides, beta lactams, glycopeptides, vancomycin

Question 42

Aerococcus

Answer 42

Airborne, opportunistic | Bacteremia, UTI in immunocompromised