streptococcal & staphylococcal infection/ Neisseria Meningitidis Flashcards
1
Q
most common cause of pyogenic infection of the skin
and soft tissues
A
Staphylococcus aureus
2
Q
bacteremia associated with s.aureus
A
osteomyelitis, suppurative arthritis, pyomyositis, deep abscesses, pneumonia, empyema, endocarditis, pericarditis and rarely meningitis
3
Q
Toxin-mediated diseases of s.aureus
A
food poisoning,
staphylococcal scarlet fever,
scalded skin syndrome,
and toxic shock syndrome (TSS)
4
Q
interfere with opsonophagocytosis.
A
slime layer
5
Q
differentiates S. aureus from coagulase-negative staphylococci
A
clumping factor and/or coagulase
Clumping factor interacts with fibrinogen to cause large clumps of organisms, interfering with effective phagocytosis
6
Q
causes plasma to clot by interacting with fibrinogen and this may have an important role in localization of infection (abscess formation).
A
coagulase
7
Q
Present in most strains of S. aureus but not coagulase-negative staphylococci and reacts specifically with immunoglobulin G (IgG1, IgG2, and IgG4).
A
Protein A
located on the outermost coat of the cell wall and can absorb serum immunoglobulins, preventing antibacterial antibodies from acting as opsonins and thus inhibiting phagocytosis
8
Q
inactivates hydrogen peroxide, promoting
intracellular survival
A
catalaase
9
Q
inactivatespenicillin at the molecular level
A
penicillinase or B lactamase
10
Q
enzyme associate with skin infection
A
lipase
11
Q
protein that S. aureus combines with phospholipid in the leukocytic cell membrane, producing increased permeability and eventual death of the cell
A
Panton-Valentine leukocidin
Strains of S. aureus that produce Panton-Valentine leukocidin are associated with more-severe and invasive skin disease, pneumonia, and osteomyelitis.
12
Q
serologically distinct proteins that produce localized (bullous impetigo) or generalized (scalded skin syndrome, staphylococcal scarlet fever) dermatologic manifestations
A
Exfoliatin A & B
Exfoliatins produce skin separation by splitting the desmosome and altering the intracellular matrix in the stratum granulosum.
13
Q
superantigen that induces production of interleukin-1 and tumor necrosis factor, resulting in hypotension, fever, and multisystem involvement
A
Toxic shock syndrome toxin-1 (TSST-1)
associated with TSS related to menstruation and focal staphylococcal infection
14
Q
mediates adhesion to mucosal cells proteins that promote adhesion to fibrinogen,
fibronectin, collagen, and other human proteins
A
teichoic acid
15
Q
responsible for the methicillin resistance of MRSA isolates
A
altered PBP-2A
16
Q
risk factor for the development of infection
A
disruption of intact skin, including breaches from wounds,
skin disease such as eczema, epidermolysis bullosa or burns,
ventriculoperitoneal
shunts, and indwelling intravascular or intrathecal catheters
malnutrition
corticosteroid
azotemia
17
Q
congenital defects that increase risk for staph infection
A
Congenital defects in chemotaxis (Job syndrome, Chédiak-Higashisyndrome, Wiskott-Aldrich syndrome)
and defective phagocytosis and killing (neutropenia, chronic granulomatous disease)
18
Q
skin infection caused by staph
A
impetigo contagiosa, ecthyma, bullous impetigo, folliculitis, hydradenitis, furuncles (boils), carbuncles (multiple coalesced boils), paronychia, staphylococcal scalded skin syndrome, and staphylococcal scarlet fever,
19
Q
respiratory manifestation of staph
A
otitis media, sinusitis
membranous tracheitis
high fever, leukocytosis and evidence of severe upper airway obstruction
20
Q
direct laryngoscopy or bronchoscopy of staph
A
normal epiglottis with subglottic narrowing and thick, purulent secretions within the trachea
21
Q
necrotizing pneumonitis may be associated with
A
early development of empyema, pneumatocele, pyopneumothorax and bronchopleural fistula
22
Q
characteristic of disseminated s.aureus disease
A
fever, persistent bacteremia despite antibiotics, and focal involvement of 2 or more separate tissue sites (skin, bone, joint, kidney, lung, liver, heart).
23
Q
Localized staphylococcal abscesses in muscle sometimes without septicemia
A
pyomyositis
24
Q
most common cause of osteomyelitis and suppurative
arthritis in children
A
s.aureus
25
true or false:
| Meningitis caused by s.aureus is common
false
26
CNS infection caused by s.aureus is associated with
penetrating cranial trauma and neurosurgical procedures (craniotomy, cerebrospinal fluid [CSF] shunt placement), and
less frequently with endocarditis, parameningeal foci (epidural or brain abscess), diabetes mellitus, or malignancy
27
common cause of acute endocarditis on native valves, and results in high rates of morbidity and mortality
s. aureus
Perforation of heart valves, myocardial abscesses, heart failure, conduction disturbances, acute hemopericardium, purulent pericarditis, and sudden death may ensue
28
true or false
Pyelonephritis and cystitis
caused by S. aureus are unusual
true
common cause of renal and perinephric abscess usually of hematogenous origin
29
fever, shock &/ scarlet fever like rash
toxic shock syndrome
30
rarely follows overgrowth of normal bowel flora by S. aureus, which can occur as a result of broad-spectrum oral antibiotic therapy
staphylococcal enterocolitis
31
in staphylococcal food poisoning, how long will severe vomiting begin?
approx 2-7hrs after ingestion of toxin.
Watery diarrhea may develop, but fever is
absent or low. Symptoms rarely persist longer than 12-24 hr. Rarely,
shock and death may occur.
32
best culture material
Tissue samples or fluid aspirates in a syringe
33
Initial treatment for serious infections thought to be caused by methicillin-susceptible S. aureus
semisynthetic penicillin (e.g., nafcillin) or a first-generation cephalosporin (e.g., cefazolin)
34
true or false
Antistaphylococcal penicillins and cephalosporins provide activity against MRSA
false
35
initial treatment for drug penicillin-allergic individuals and those with
suspected serious infections caused by MRSA
vancomycin (10-20 μg/mL)
36
true or false
Clindamycin is bacteriostatic and should be used to treat endocarditis, brain abscess, or meningitis caused by S. aureus.
false
37
acute and potentiallysevere illness characterized by fever, hypotension, erythematous rash with subsequent desquamation on the hands and feet, and multisystem involvement, including vomiting, diarrhea, myalgias, nonfocal neurologic abnormalities, conjunctival hyperemia, and strawberry tongue
Toxic Shock Syndrome
38
pathogenesis of TSS
toxins act as a superantigens, which trigger cytokine release causing massive loss of fluid from the intravascular space and end-organ cellular injury
39
complication of TSS
acute respiratory distress syndrome, myocardial dysfunction, and renal failure
40
recovery of TSS associated with desquamation happens on what day?
7-10days
41
Diagnostic criteria of TSS
MAJOR CRITERIA (ALL REQUIRED)
1. Acute fever; temperature >38.8°C (101.8°F)
2. Hypotension (orthostatic, shock; blood pressure below age appropriate norms)
3. Rash (erythroderma with convalescent desquamation)
MINOR CRITERIA (ANY 3 OR MORE)
1. Mucous membrane inflammation (vaginal, oropharyngeal or
conjunctival hyperemia, strawberry tongue)
2. Vomiting, diarrhea
3. Liver abnormalities (bilirubin or transaminase greater than twice upper limit of normal)
4. Renal abnormalities (urea nitrogen or creatinine greater than twice upper limit of normal, or greater than 5 white blood cells per
high-power field)
5. Muscle abnormalities (myalgia or creatinine phosphokinase greater
than twice upper limit of normal)
6. Central nervous system abnormalities (alteration in consciousness without focal neurologic signs)
7. Thrombocytopenia (100,000/mm3 or less)
EXCLUSIONARY CRITERIA
1. Absence of another explanation
2. Negative blood cultures (except occasionally for Staphylococcus
aureus)
42
hair loss in TSS is observed how many months after toxin infltration
1-2 months
43
most common and persistent species, representing
| 65-90% of staphylococci present on the skin and mucous membranes
s.epidermidis
44
pathogenesis of CONS
CoNS produce an exopolysaccharide protective biofilm, or slime
layer, that surrounds the organism and may enhance adhesion to foreign surfaces, resist phagocytosis, and impair penetration of antibiotics.
45
manifestation of CONS bacteremia
apnea, bradycardia, temperature instability,
| abdominal distention, hematochezia, meningitis in the absence of CSF pleocytosis, and cutaneous abscesses.
46
common cause of prosthetic valve endocarditis,
| presumably a result of inoculation at the time of surgery
CONS
47
true or false
Central venous catheters become infected through the exit site and
subcutaneous tunnel, which provide a direct path to the bloodstream
true
48
manifestation of line sepsis
fever, leukocytosis, tenderness, erythema
49
Most (70-80%) infections
occur within __ mo of the operation and are manifested by signs of
meningeal irritation, fever, increased intracranial pressure (headache),
or peritonitis from the intraabdominal position of the distal end of the shunt tubing.
2 months
50
common cause of primary urinary tract infections
| in sexually active females
S. saprophyticus
51
DOC for methicillin resistant stain
vancomycin
52
Which of the following is not true regarding N. meningitides?
A. Smoking and influenza virus are asscoiated with increase carriage and disease.
B. Highest rate of meningococcal disease occurs in infants < 1 year old.
C. Carriage peaks in early childhood and is unusual in adolescence and young adulthood.
D. MSM, binge drinking, bar patronage increase disease risk.
C. Carriage peaks in early childhood and is unusual in adolescence and young adulthood.
Carriage is unusual in early childhood, and peaks in adolescence and young adulthoood.
53
```
The following are all common features in severe septicemia, EXCEPT:
A. Hypoglycemia
B. Acidosis
C. Hyperglycemia
D. Hypophosphatemia
E. Hypokalemia
```
C. Hyperglycemia
Hypoglycemia is a common feature
54
The most common form of menigococcal infection is:
A. Meningococcal meningitis
B. Occult bacteremia
C. Meningococcal septicemia with or without meningitis
D. Asymptomatic carriage in the nasopharynx
Asymptomatic carriage in the nasopharynx
55
Which of the following statements is not true about meningococcemia?
A. Chronic meningococcemia does not spontaneously resolve and meningitis surely develops in untreated cases.
B. Seizures and focal neurologic signs occur less frequently than in patients with meningitis caused by H. Influenza and S. pneumonia.
C. Focal infections in bone, eye, peritoneum, sinuses and amiddle ear are well recognized.
D. As the disease progreses, nonblanching or petechial rash will develop in 80% of cases.
A. Chronic meningococcemia does not spontaneously resolve and meningitis surely develops in untreated cases.
Chronic meningococcemia may spontaneously resolve but meningitis may develop in untreated cases
56
The following statements are true, EXCEPT:
A. Meningococci may be indentified in a Gram stain preparatin and/or culture of petechial purpuric skin lesions
B. Isolation of organism from the nasopharynx is diagnostic of invasive disease.
C. CSF culture results may be positive in patients with meningococcemia in the absence of CSF pleocytosis.
D. CSF specimens that are gram positive are sometimes culture negative.
B. Isolation of organism from the nasopharynx is diagnostic of invasive disease.
Isolation of organism form the nasopharynx is not diagnostic of invasive disease because the organism is a common commensal
57
]recommended treatment for invasive N. meningitides in neonates:
Cefotaxime 200-300mg/kg/day
58
most frequent neurologic sequelae of meningitis, occurring in 5-10% of children is
deafness
59
The presence of the ff indicate rapid, fulminant progression and poorer prognosis, EXCEPT:
A. purpura fulminans
B. low or normal ESR
C. petechiae less than 12hrs before admission
D. absence of meningitis
purpura fulminans
60
```
Which among these drugs is not routinely used as prophylaxis for Meningococemia
1/1
A. Rifampicin
B. Ciprofloxacin
C. Azithromycin
D. Ampicillin
```
D. Ampicillin
together with PenG are not used because it does not eradicate nasopharyngeal carriage
61
The ff are true regarding administration of secondary protection among those at risk for Meningococcemia after exposure except:
A. Those who frequently slept in same dwelling as index patient during 7 days before onset of illness.
B. Passengers seated directly next to index case during airline flights lasting >10hrs
C. household contact, especially children < 2yo
D. mouth to mouth resuscitation, unprotected contact during ET intubation during 7 days before onset of illness.
B. Passengers seated directly next to index case during airline flights lasting >10hrs
62
Which of the following statement is false regarding Staphylococcus?
1/1
a. PBP-2A is responsible for the methicillin and cephalosporin resistance of MRSA isolates.
b. Ingestion of preformed enterotoxin, particularly types A and B can result in food poisoning with S. aureus
c. The staphylococcal coagulase inactivates hydrogen peroxide, promoting intracellular survival.
d. Most staphylococci produce biofilm which may interfere with opsonophagocytosis.
c. The staphylococcal coagulase inactivates hydrogen peroxide, promoting intracellular survival.
The staphylococcal catalase inactivates hydrogen peroxide, promoting intracellular survival
63
The most significant risk factor for the development of infection of Staphylococcal infection is
Disruption of intact skin
64
Which of the ff is true regarding treatment of Staphylococcal infection:
A. Penicillin and ampicillin are appropriate empiric therapy for MSSA.
B. B-lactamase inhibitors when added to a penicillin-based drug confers activity against MRSA
C. Clindamycin is used to treat TSS due to its action as a cell wall inhibitor 3
D. Carbapenems have activity on both MRSA and MSSA
E. All of the statements are not true
E. All of the statements are not true
65
```
Which of the ff is may be an adjunctive agent to B-lactam or vancomycin in infections like endocarditis specifically involving prosthetic valve?
1/1
A. Oxacillin
B. Ceftaroline
C. Colistin
D. Rifampicin
```
D. Rifampicin
66
The most effective measure to preventing spread of staphylococci from between individuals is?
1/1
A. isolation of affected staphylococcal patients
B. strict hand hygiene practices
C. decolonization
D. Constant surveillance of staphylococcal infections within hospitals
B. strict hand hygiene practices
67
```
Initial empiric treatment for non-life threatening infection without signs with low likelihood of MRSA suspected is?
A. Cotrimoxazole
B. Clindamycin
C. Cefazolin
D.Oxacillin
```
C. Cefazolin
68
Food poisoning caused by staphylococci is described as follows except:
A. Severe vomiting could be present as early as 8 hrs after ingestion of the toxin1
B. Fever is absent or low.
C. Symptoms rarely persist >48 hrs (symptoms rarely persist >12-24 hrs
D. Shock and death are rare
C. Symptoms rarely persist >48 hrs (symptoms rarely persist >12-24 hrs
69
```
Major criteria for Staphylococcal Toxic Shock Syndrome include the ff except:
A. rash with convalescent desquamation
B. acute fever >38.8
C. thrombocytopenia
D. Hypotension
```
C. thrombocytopenia (minor criteria)
70
The most common cause of nosocomial bacteremia usually associated with CVC is
staph epidermidis
71
The ff. differentiates CONS bacteremia from contamination, EXCEPT:
A. > 1 blood culture is positive with the samw CONS strain
B. Symptoms compatible with CONS sepsis resolve with appropriate antibiotics
C. Blood culture grow rapidly within 48 hrs
D. Centeal and peripheral cultures are positive
C. Blood culture grow rapidly within 48 hrs
72
```
The following describe Streptococcus pneumonia bacteria, EXCEPT:
1/1
A. Optochin +
B. Bile soluble
C. Encapsulated
D. Catalase positive
```
D. Catalase positive
73
The ff. statements are true about Strep pneumonia, EXCEPT:
A. Polysaccharide pneumococcal vaccine is effective for children less than 2 yo
B. Rates of pneumococcal carriage peak during the first 2 yrs of life
C. Males are more frequently infected than females
D. Patients with cochlear implants are at increased risk.
A. Polysaccharide pneumococcal vaccine is effective for children less than 2 yo
Children <2 yrs have decreased ability to produce antibody against T-cell independent polysaccharide antigen hence the decreased effectiveness of pokysaccharide vaccine
74
This test should be performed to determine whether clindamycin resistance can be induced by erythromycin resistance
D-test
75
```
Which of the ff. is not part of the clinical criteria for defining streptococcal Toxic Shock Syndrome ?
A. Hepatic involvemenr
B. Hypotension
C. Gastrointestinal manifestations
D. Coagulopathy
```
C. Gastrointestinal manifestations
76
Which of the ff. is not true about Grouo A Strep pharyngitis?
1/1
A. Resistant strains against Penicillin and Cephalosporins have never been encountered
B. Recommended duration of treatment is 7 days.
C. Post treatment throat cultures are indicated only in certain situations.
D. Acute RF only follows an infection of the upper respiratory tract.
B. Recommended duration of treatment is 7 days.
77
The ff. statements are true about Poststreptococcal reactive arthritis (PSRA), EXCEPT:
1/1
A. Arthritis is nonmigratory
B. Arthritis responds dramatically with aspirin
C. May involve axial skeleton
D. Latent period between antecedent GAS pharyngitis and PRSA is shorter than in RF
B. Arthritis responds dramatically with aspirin
78
Which of the ff. statements is true about Rheumatic Fever?
A. Diagnosis of recurrent acute RF can be made only in high risk population by presence of 2 minor with evidence of preceding GAS infection.
B. Arthritis as one of the major criteria refers only to polyarthritis in low-risk areas but also monoarthritis and polyarthritis in high-risk areas.
C. Acute RF typically develops 10-28 days after an acute GAS infection.
D. Patients with carditis and/or congestive heart failure should not receive steroids
B. Arthritis as one of the major criteria refers only to polyarthritis in low-risk areas but also monoarthritis and polyarthritis in high-risk areas.
79
Which is the treatment of choice in maternal chemoprophylaxis against GBs infection?
Pen G
80
```
The following are alpha-hemolytic Streptococci, EXCEPT:
A. Group C Strep
B. Streptococcus mitis
C. Streptococcus viridans
D. Streptococcus bovis
```
A. Group C Strep
81
The ff. statements are true regarding GBS infection, EXCEPT:
A. Administration of maternal chemophrophylaxis before onset of labor is an effective means of eradicating maternal GBS colonization and consequently preventing neonatal GBS infection.
B. Vaginorectal GBS screening cultures must be performed for all pregnant women at 35-37 weeks.
C. UNcomplicated meningitis is treated for 14 days.
D. Late-onset neonatal GBS infection presents at > /= 7 days of life.
A. Administration of maternal chemophrophylaxis before onset of labor is an effective means of eradicating maternal GBS colonization and consequently preventing neonatal GBS infection.
