Gram Positive Cocci

Question 1

Gram positive

Answer 1

purple

Question 2

Gram positive cocci

Answer 2

Staphylococcus
Streptococcus
Enterococcus

Question 3

Gram positive cocci

Catalase positive

Answer 3

Staphylococcus

Question 4

S. aureus characteristics

Answer 4

Gram positive cocci
Catalase positive
Coagulase positive
Beta hemolytic
Mannitol fermentation

Question 5

Main virulence factor S. aureus

Answer 5

Protein A

binds Fc preventing opsonization

Question 6

S. aureus colonizes

Answer 6

Nares

Question 7

S. aureus diseases

Answer 7

Pneumonia
Septic arthritis
Cellulitis, Impetigo etc.
Acute bacterial endocarditis
Osteomyelitis

Question 8

Characteristics of S. aureus pneumonia

Answer 8

patchy infiltrate on CXR

secondary post-viral bacterial infection

Question 9

S. aureus is the most common cause of

Answer 9

septic arthritis

Question 10

Consider which S. aureus disease in IV drug users

Answer 10

Acute bacterial endocarditis

Question 11

S. aureus toxin-mediated syndromes

Answer 11

Scalded-skin syndrome
Toxic Shock Syndrome
Food Poisoning

Question 12

Toxin associated with scalded-skin syndrome

Answer 12

exfoliative toxin

Question 13

Toxin associated with TSS

Answer 13

TSST-1

Question 14

MOA of TSST-1

Answer 14

non-specific binding of MHC II and T-cell receptors resulting in overactivation and cytokine storm

Question 15

Toxin associated with food poisoning

Answer 15

Enterotoxin

1-8h

Question 16

MRSA

Answer 16

alters PBPs
use vancomycin
sensitive - use nafcillin

Question 17

Enemy of orthopedic surgeons

Answer 17

S. epidermidis

affects artificial joints, hardware, catheters

Question 18

S. epidermidis characteristics

Answer 18

Gram positive cocci
Catalase positive
Coagulase negative
Urease positive
Novobiocin sensitive

Question 19

Most common cause of endocarditis of artificial heart valves

Answer 19

S. epidermidis (biofilms)

Treat with vancomycin

Question 20

S. saprophyticus characteristics

Answer 20

Gram positive cocci
Catalase positive
Coagulase negative
Urease positive
Novobiocin resistant

Question 21

S. saprophyticus is common cause of

Answer 21

UTI in sexually active females

Question 22

Gram positive cocci

Catalase negative

Answer 22

Streptococcus

Question 23

GAS characteristics

Answer 23

Streptococcus pyogenes
Gram positive cocci in lines
Catalase negative
Bacitracin sensitive
Beta hemolytic

Question 24

Clinical infections of GAS

Answer 24

Impetigo - honey crusted
Pharyngitis
Erysepela/cellulitis

Question 25

Major toxin of GAS

Answer 25

SPE - strep pyogenic exotoxin

Question 26

SPE mediated diseases

Answer 26

Scarlet Fever Toxic Shock-Like Syndrome Necrotizing Fasciitis

Question 27

Scarlet Fever

Answer 27

Red/swollen strawberry tongue Pharyngitis Widespread rash sparing face

Question 28

TSLS

Answer 28

Similar to TSST-1

Question 29

Necrotizing Fasciitis

Answer 29

invades fascia under skin

Question 30

Subgroups of SPE

Answer 30

SpeA - SF and TSLS SpeB - NF SpeC - SF and TSLS

Question 31

Associated conditions and complications of GAS

Answer 31

Rheumatic Fever | Post-Strep Glomerulonephritis

Question 32

Rheumatic fever

Answer 32

M-protein - highly antigenic - Type II HSN Interferes w/opsonization and initiates immunogenic response Ab against myosin in heart - mitral valve

Question 33

JONES criteria of RF

Answer 33

Joints - polyarthritis Heart - valvular damage, murmurs, myocarditis etc. Nodules - subcutaneous nodules of forearm, elbows, knees E - erythema marginatum S - Sydenham Chorea

Question 34

PSGN

Answer 34

Type III HSN dark brown urine fascial swelling 2 weeks after strep infection

Question 35

Difference between RF and PSGN

Answer 35

PSGN can occur after both pharyngitis or skin infection; RF only after pharyngitis Early TX can prevent RF; cannot prevent PSGN

Question 36

Virulence factors of GAS

Answer 36

Streptolysin O - lyse RBC - beta hemolytic - generate ASO Ab Streptokinase DNAse

Question 37

GBS characteristics

Answer 37

``` Streptococcus agalactiae Gram positive cocci Catalase negative CAMP positive* Beta hemolytic Hippurate positive Bacitracin resistant ```

Question 38

GBS causes serious infections in

Answer 38

Newborns Infected as baby passes through vaginal canal Mothers get cultured at 35 weeks Positive - intrapartum PCN

Question 39

Clinical presentations of GBS

Answer 39

Neonatal meningitis - most common cause Neonatal sepsis Neonatal pneumonia

Question 40

Alpha hemolytic Strep

Answer 40

S. pneumoniae | S. viridans

Question 41

S. pneumoniae characteristics

Answer 41

``` Gram positive diplococci catalase negative Alpha hemolytic Optochin sensitive Bile soluble ```

Question 42

S. pneumoniae VFs

Answer 42

Polysaccharide capsule IgA protease Common infections in sickle cell

Question 43

S. pneumoniae vaccines

Answer 43

23 valent polysaccharide for adults - IgM | 7 valent conjugated for children - IgG

Question 44

Common clinical presentations of S. pneumoniae

Answer 44

Meningitis Otitis Media Pneumonia - rust colored, lower lobes - #1 community acquired pneumonia Sinusitis

Question 45

S. viridans characteristics

Answer 45

``` Gram positive cocci catalase negative alpha hemolytic Optochin resistant Bile resistant no capsule ```

Question 46

S. viridans associations

Answer 46

Dental caries - S. mutans | Endocarditis - S. sanguinis

Question 47

Enterococcus characteristics

Answer 47

Gram positive cocci Intestinal tract Grows in 6.5% NaCl Bile resistant

Question 48

Treatment of VRE

Answer 48

Linezolid | Tigecycline

Question 49

Enterococcus presentations

Answer 49

UTI Endocarditis Biliary tree infections