3rd year > bacteriology > Flashcards

bacteriology Flashcards

(53 cards)

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1
Q

General characteristics of S. aureus are

A
  • Gram-positive cocci
  • Catalase positive
  • Nonmotile
  • Aerobic or facultatively anaerobic
  • Medium, circular and entire, smooth, convex, and usually white-to-yellow colonies
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2
Q

Transmission of Staphylococcus

A
  • Person-to-person
    Persistent carriers
    Intermittent carriers
    Noncarriers
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3
Q

Capsule

A
  • Slime laver
  • Biofilm
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4
Q

Cell wall

A
  • Peptidoglycan
  • Protein A
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5
Q

Disrupts smooth muscle and toxic to many cell types

A

Alpha toxins

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6
Q

Heat labile sphingomyelinase

A

Beta toxins

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7
Q

Cytotoxic to erythrocytes

A

Delta toxins

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8
Q

Mav function in association with Panton-Valentine Leuckocidin (PVL)

A

Gamma toxins

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9
Q

Heat stable enterotoxins in up to

A

50% of S. aureus strains

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10
Q

Localized skin infections

A
  • Folliculitis
  • Furuncles
  • Carbuncles
  • Impetigo
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11
Q

Infections in those who are immunocompromised

A

microcccus

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12
Q
  • Skin and soft-tissue infections
  • Toxic shock syndrome (TSS)
  • Food poisoning
  • Scalded skin syndrome
A

S. aureus

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13
Q

*Associated with UTIs in sexually active young women

A

S. saprophyticus

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14
Q

Panton- Valentine leukocidin (PVL) toxin

A

S. aureus

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15
Q

community -associated infections

A

MRSA or CA-MRSA

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16
Q
  • Usually infects neonates
  • Cause extensive sloughing of epidermis to produce a burn like effect on the patient
A

Scalded skin syndrome

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17
Q

Systemic effects on the patients; including fever, desquamation, hypotension leading to shock and death

A

Toxic Shock syndrome

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18
Q

Virulence Factors of Staphylococcus aureus

A
  • Produce and secretes toxins and enzymes
  • Leucocidin mediates destructio of phagocytes
  • Clumping factor
  • Coagulase
  • Hyaluronidase
  • Potent exotoxins (TSST-1) and enterotoxin
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19
Q

Spectrum of Diseases and infections in Staphylococcus aureus

A
  • Necrosis
  • Localized skin infections
  • Folliculiis
  • Furuncles (Boils)
  • Carbuncles
  • Impetigo
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20
Q
  • Coagulase negative staphylococci
  • Less virulent
  • Their prevalence as nosocomial infection is ,if not more related to medical procedures and practices
A

Staphylococcus epidermidis

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21
Q

virulence of epidermidis

A
  • Certain factors facilitate attachment to implanted medical devices
  • Production of exopolysaccharide “slime” or biofilm
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22
Q

INFECTIONS of epidermidis

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A
  • Ubiquitous (contaminant)
  • Difficult to establish clinical significance
  • Nosocomial bacterimia
23
Q
  • Involve implantation of medical devices
  • Production of slime layer or biofilm that facilitates attachment to implanted medical devices.
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A

S. haemolyticus and S. lugdunensis

24
Q
  • Community acquired UTI in young sexually active females
  • Not commonly associated with hospital-acquired infections,
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A

S. saprophyticus

25
* Virulence factor-UNKNOWN * Rarely associated with infection * Low virulence
micrococcus
26
* May appear as catalase + * Aerococcus * Enterococcus * Rothia (forrmerly Stomatococcus)
Pseudocatalase reaction
27
Rapid method to differentiate Staphylococcus from Micrococcus.
microdase test
28
blue to purple blue color
+ - micrococcus
29
No color change
- staphylococcus
30
Micrococcus
- Not lysed with lysostaphin - Susceptible to 0.04U bacitracin - Resistant to the antibiotic furazolidone - microdase positive
31
staphylococcus
- Lysed with lysostaphin - Resistant to 0.04U bacitracin - Susceptible to furazolidone - Microdase-negative - Facultatively anaerobic
32
Bound
* Clumping factor * Rapid slide test
33
Free
* Extracellular (free) coagulase * Tube coagulase test * Clot formation witin 1-4 hours of inoculation
34
Most laboratories do not identify coagulase negative staphylococci; EXCEPT:
* Isolates from normally sterile sites: * Blood * Joint fluid * CSF * Isolates from prosthetic devices * Catheters * Shunts * Isolates from UTI that may be S. saprophyticus
35
* Antibodies to teichoic acid * Performed in reference laboratories
SERODIAGNOSIS
36
Antimicrobial susceptibility testing and therapy Antistaphyococcal therapy
* Penicillinase-resistnt penicillin * Methicillin * Nafcillin * Oxacillin
37
* most commonly used cell-wall active agent that retains activity * Alternative drug for resistant strain
VANCOMYCIN
38
two newer agents available for use agains resistant strains
* Linezolid * Daptomycin
39
* Rarely encountered infections in humans * Therapeutic guidelines and standardized testing methods do not exist. * Appear to be susceptible to most beta-lactam antimicrobials
micrococcus spp.
40
Prevention of staphylococcus
* No approved antistaphylococcal vaccines * Health careworkers identified as intranasal carriers of an epidemic strain of S. aureus. Treated with muciprocin and in some cases, with rifampin.
41
Some doctors recommended use of antibacterial substances to umbilical cord stump to prevent staphylococcal disease in hospital nurseries such as:
* gentian violet * Acriflavie * Chlorhexidine * Bacitracin
42
Recommended that all full terms infants be bathed with __________ as soon after birth as possible and daily after discharge
3% hexachlorophene
43
Normal flora of anterior nares, nasopharynx, perineal area, & skin
S. aureus
44
Normal flora of skin and mucous membrane
S. epidermidis
45
Similar to S epidermidis, but in lower number
S. haemolyticus & lugdunensis
46
Normal flora of the skin and mucosa of GUT
S. saprophyticus
47
Normal flora of the skin mucosa and oropharnyx
Micrococcus spp.
48
Traumatic introduction, person person, fomites, air (TPFA)
S. aureus
49
Implantation of medical devices; person to person
S. epidermidis
50
Same with S. epidermidis
S. haemolyticus & lugdunensis
51
- Introduction of edogenoua flora into sterile urinary tract, - Community acquired infection
S. saprophyticus
52
Uncertain
Micrococcus
53
Colonial on 5% sheep blood agar
S. aereus - beta hemolytic S. epidermidis - Non hemolytic S. haemolyticus & lugdunensis - beta hemolytic S. saprophyticus - yellow to orange colonies Micrococcus - Non hemolytic (gamma)
3rd year
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