staphylococci

Question 1

pyogenic

Answer 1

pus-forming

Question 2

staphylococci are able to survive in ____ environments

Answer 2

salty

Question 3

Mannitol Salt Agar (MSA)

S. aureus ferments the mannitol, releasing acid byproduct, causing phenol red pH indicator in agar to change to ______

Answer 3

yellow.

Question 4

Responsible for a broad spectrum of clinical syndromes

Answer 4

Staphylococcus aureus

Question 5

Medical device-related infections

Answer 5

Staphylococcus epidermidis

Question 6

Urinary tract infections

Answer 6

Staphylococcus saprophyticus

Question 7

Hospital Acquired S. aureus are mostly drug resistant (e.g. Methicillin Resistant S. aureus [MRSA], Vancomycin Resistant S. aureus [VRSA]).

Answer 7

yep

Question 8

Community Acquired S. aureus infections (CA-SA) generally have more treatment options, but

Answer 8

drug resistance is emerging

Question 9

The reservoir for S. aureus in adults is the human axillae (armpits), nares, and external genitalia. In neonates, S. aureus is found in the umbilical stump, perineum, skin and gastrointestinal tract.

The carriage rate is approximately 30% in the general population. Health care workers as well as diabetics, intravenous drug users and patients on hemodialysis have higher carriage rates.

Answer 9

yep

Question 10

main rout of entry for S.aureus

Answer 10

S. aureus gains entry to deeper tissues after trauma, surgery or instrumentation breach integrity of the skin or mucous membranes.

Question 11

S. aureus is specialized for survival in the host as an

Answer 11

extracellular pathogen

Question 12

S. aureus has Many Potent Virulence Factors (4)

Answer 12

1. Inhibitors of phagocytosis
2. Cell-associated adhesins for tissue colonization (many bind extracellular matrix proteins)
3. Secreted proteins for the creation of a hospitable extracellular milieu
4. Secreted toxins for nutrient acquisition and immune escape

Question 13

inhibitors of phagocytosis that S. aureus has (3)

Answer 13

1. Protein A.
2. polysaccharide capsule
3. coagulase

Question 14

Release nutrients from host
tissue aiding growth, and also
also allow for dissemination of
bacteria (3)

Answer 14

1. proteases
2. lipases
3. DNases

Question 15

numerous exotoxins exist like membrane-damaging toxins and superantigens

Answer 15

yep

Question 16

superatnigens

Answer 16

activates t-cells (high 20%) with a high cytokine release by bridging TCR and MHC II

Question 17

superantigen toxin-related disease

Answer 17

1. toxic shock syndrome
2. menstrual
3. non-menstrual
4. food poisoning
5. S. scalded skin syndrome

Question 18

resistant to many beta-lactams due to acquisition of mecA gene encoding alt. peptidoglycan synthesis protein

Answer 18

MRSA- methicillin-resistant

Question 19

Is the result of a thickened peptidoglycan layer.

Vancomycin is less able to penetrate.

Answer 19

VISA-Vancomycin-intermediate

Question 20

Acquisition of the vanA gene, originally from vancomycin-resistant
Enterococcus. (VanA makes D-alanine-D-lactate peptide cross-bridge
precursors in cell wall instead of the usual D-alanine-D-alanine.)

Answer 20

VRSA- Vancomycin-resistant

Question 21

S. epidermidis is a normal inhabitant of human skin.

Answer 21

yep

In the normal host, S. epidemidis cannot cause
infection in the absence of a foreign body,
even if the skin has been compromised.
Exceptions are neonates, IV drug users.

Question 22

S.epidermis adhesins (3) to biomaterials

Answer 22

1. fimbriae- surface structures
2. AtlE
3. capsular polysaccharide

Question 23

threapy for device related S. epidermidis

Answer 23

removal of the foreign body and then treat vancomycin

Question 24

therapy to S. saprophyticus

Answer 24

no different than other UTI pthogens

Question 25

golden, Beta-hemolytic colonies, can ferment mannitol.

Answer 25

S. aureus

Question 26

white, non-hemolytic, cannot | ferment mannitol.

Answer 26

S. epidermidis

Question 27

Gram-positive cocci, chains or diplococci, | catalase-negative

Answer 27

streptococci

Question 28

Group A Strep (GAS)

Answer 28

S. pyogenes –

Question 29

Group B Strep (GBS)

Answer 29

S. agalactiae –

Question 30

Group D Strep (GDS)

Answer 30

S. bovis –

Question 31

serotyping scheme based on cell wall carbohydrate antigens

Answer 31

Lancefield groups—

Question 32

type of hemolysis green/brown zone | around colonies

Answer 32

Alpha-hemolysis ***Alpha is due to breakdown of hemoglobin and other molecules in RBSs, not really lysis of RBCs.

Question 33

type of hemolysis: complete lysis, and clearing

Answer 33

Beta-hemolysis

Question 34

type of hemolysis: non-hemolytic

Answer 34

gamma-hemolysis

Question 35

S. pyogenes is found

Answer 35

on skin and mucosal surfaces of humans

Question 36

Skin and mucous membrane infections Strep throat -Colder weather; spread mainly by aerosol Impetigo -Warmer weather; contact transmission Erysipelas -Infection of the upper levels of dermis Deep tissue and blood infection Cellulitis Necrotizing fasciitis, myositis Pneumonia, puerperal fever (infection of placenta) Toxigenic manifestations Scarlet Fever (erythrogenic toxin [a superantigen]) Streptococcal toxic shock syndrome (strep TSS) due to superantigen expression

Answer 36

suppurative GAS disesase

Question 37

cellulitis

Answer 37

deeper infection of skin and can rapidly spread tx. with oral antibiotics

Question 38

strawberyy tongue associated with

Answer 38

Scarlet fever - GAS toxigenic manifestations

Question 39

A. Glomerulonephritis - Follows pharyngitis or impetigo, 10-15% attack rate - Antigen-antibody-complement complex deposited in kidney - Edema, smoky or rust colored urine, hypertension B. Acute rheumatic fever Valvular Heart Disease Follows untreated pharyngitis and/or scarlet fever, not impetigo Presents 1-5 weeks post-pharyngitis Fever, rash, arthritis, carditis, movement disorder (chorea) Caused by specific subset of GAS strains Proposed pathogenesis: autoimmunity Generation of cross-reactive antibodies recognizing heart Prevention: Rx pharyngitis with 10 d of antibiotics Now rare in US, but in developing countries a major cause of heart disease

Answer 39

non-suppurative complications of GAS infection

Question 40

major GAS virulence factor

Answer 40

surface localized "M protein"

Question 41

roles of M protein (3)

Answer 41

1. attachment 2. resistance of phagocytosis 3. resistance to complement

Question 42

M protein importance in immunity

Answer 42

Anti-M protein IgG is protective

Question 43

pore forming toxins in GAS exotoxins which important for necrotizing fascitis cause what type of hemolysis

Answer 43

beta

Question 44

Therapy for GAS

Answer 44

1. penicillin-sensitive

Question 45

S. agalactiae normally found in

Answer 45

lower GI tract which can colonize female genital tract leading to infection during birth

Question 46

S. bovis a GDS species is common in

Answer 46

bowel flora however when found in bloodstream it correlates with colon cancer and it is a significant cause of endocarditis

Question 47

enterococci normally inhabit the

Answer 47

GI tract

Question 48

enterococci can cause _____ and it is resistant to _____ and it is inhibited but not killed by _____

Answer 48

enterococci can cause endocarditis and it is resistant to cephalosporins and it is inhibited but not killed by penicillin

Question 49

Group of a-hemolytic , and some g-hemolytic (non-hemolytic) streptococcal species, that are commensals, and are of low virulence. Most are oral commensal bacteria isolated from dental plaque Cause of subacute endocarditis

Answer 49

viridans streptococci

Question 50

alpha–hemolytic (green/brown zone), not in a Lancefield group Mucosal pathogen, typically extracellular Asymptomatic nasopharynx carriage rate of ~15-25% Common cause of otitis media and community-acquired pneumonia Less frequently causes bacteremia and bacterial meningitis Estimated 1.6M annual deaths worldwide Capsular polysaccharide-based vaccines are protective but don’t cover most serogroups

Answer 50

s. pneumoniae- pneumococcus

Question 51

pneumoccocal lung infection causes

Answer 51

lobar pneumonia characterized by inflammatory exudate within the intra-alveolar space ** patchy bronchopneumonia can also occur

Question 52

severe complication of pneumococcal that causes the brain to be covered with inflammatory exudate (pus)

Answer 52

pneumococcal meningitis

Question 53

encounter of oneumococcus

Answer 53

aerosols, mucus exchange and formites

Question 54

host immunity that is protective of pneumococcus from inflammed lung to bloodstream (bacterimia"

Answer 54

anti-capsular antibody

Question 55

virulence factors of pneumococcus (4)

Answer 55

1. surface and secreted IgA1 protease 2. surface phosphoryl choline- resists antimicrobial peptides 3. pneumolysin: pore forming toxin that impairs mucociliary clearance and kills neutrophils 4. polysaccharide capsule- essential for colonization and virulence and protective of anticapsular ab

Question 56

capsular polysacchrides each conjugated to a protein to promote T-cell-dependent response 1999: (PCV7 [pneumococcal conjugate vaccine 7-valent ]) 2010: 13-valent (PCV13 or Prevnar13)

Answer 56

Conjugative vaccine for children < 5 yo and elderly >64 yo for pneumococcal

Question 57

(PPSV23 [pneumococcal polysaccharide vaccine 23-valent]) People with splenectomy Elderly—every 10 years or so (along with PCV13) Pre-existing lung conditions

Answer 57

nonconjugated vaccine of 23 common capsular polysacchrides for pneumococcal

Question 58

therapy for pneumococcal infection

Answer 58

1. penicillin-sensitive but some resistant so treat with ceftriaxoneand vancomycin * *** penicillin allergic pt. treat with fluroquinoline

Question 59

identification of pneumococcus: 1. Gram stain: 2. Culture on blood agar: 3. Serotype determination by Quellung reaction

Answer 59

1. Gram stain: Gram-positive diplococci 2. Culture on blood agar: - a-hemolytic - Optochin-sensitive (disk diffusion test) 3. Serotype determination by Quellung reaction - Serotype-specific antibody causes cross-linking of cells and apparent swelling