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3rd year > bacteriology > Flashcards

bacteriology Flashcards

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

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.
A

S. haemolyticus and S. lugdunensis

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

S. saprophyticus

25
Q
  • Virulence factor-UNKNOWN
  • Rarely associated with infection
  • Low virulence
A

micrococcus

26
Q
  • May appear as catalase +
  • Aerococcus
  • Enterococcus
  • Rothia (forrmerly Stomatococcus)
A

Pseudocatalase reaction

27
Q

Rapid method to differentiate Staphylococcus from Micrococcus.

A

microdase test

28
Q

blue to purple blue color

A

+ - micrococcus

29
Q

No color change

A
  • staphylococcus
30
Q

Micrococcus

A
  • Not lysed with lysostaphin
  • Susceptible to 0.04U bacitracin
  • Resistant to the antibiotic furazolidone
  • microdase positive
31
Q

staphylococcus

A
  • Lysed with lysostaphin
  • Resistant to 0.04U bacitracin
  • Susceptible to furazolidone
  • Microdase-negative
  • Facultatively anaerobic
32
Q

Bound

A
  • Clumping factor
  • Rapid slide test
33
Q

Free

A
  • Extracellular (free) coagulase
  • Tube coagulase test
  • Clot formation witin 1-4 hours of inoculation
34
Q

Most laboratories do not identify coagulase negative staphylococci; EXCEPT:

A
  • Isolates from normally sterile sites:
  • Blood
  • Joint fluid
  • CSF
  • Isolates from prosthetic devices
  • Catheters
  • Shunts
  • Isolates from UTI that may be S. saprophyticus
35
Q
  • Antibodies to teichoic acid
  • Performed in reference laboratories
A

SERODIAGNOSIS

36
Q

Antimicrobial susceptibility testing and therapy
Antistaphyococcal therapy

A
  • Penicillinase-resistnt penicillin
  • Methicillin
  • Nafcillin
  • Oxacillin
37
Q
  • most commonly used cell-wall active agent that retains activity
  • Alternative drug for resistant strain
A

VANCOMYCIN

38
Q

two newer agents available for use agains resistant strains

A
  • Linezolid
  • Daptomycin
39
Q
  • Rarely encountered infections in humans
  • Therapeutic guidelines and standardized testing methods do not exist.
  • Appear to be susceptible to most beta-lactam antimicrobials
A

micrococcus spp.

40
Q

Prevention of staphylococcus

A
  • 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
Q

Some doctors recommended use of antibacterial substances to umbilical cord stump to prevent staphylococcal disease in hospital nurseries such as:

A
  • gentian violet
  • Acriflavie
  • Chlorhexidine
  • Bacitracin
42
Q

Recommended that all full terms infants be bathed with __________ as soon after birth as possible and daily after discharge

A

3% hexachlorophene

43
Q

Normal flora of anterior nares, nasopharynx, perineal area, & skin

A

S. aureus

44
Q

Normal flora of skin and mucous membrane

A

S. epidermidis

45
Q

Similar to S epidermidis, but in lower number

A

S. haemolyticus & lugdunensis

46
Q

Normal flora of the skin and mucosa of GUT

A

S. saprophyticus

47
Q

Normal flora of the skin mucosa and oropharnyx

A

Micrococcus spp.

48
Q

Traumatic introduction, person person, fomites, air (TPFA)

A

S. aureus

49
Q

Implantation of medical devices;
person to person

A

S. epidermidis

50
Q

Same with S. epidermidis

A

S. haemolyticus & lugdunensis

51
Q
  • Introduction of edogenoua flora into sterile urinary tract,
  • Community acquired infection
A

S. saprophyticus

52
Q

Uncertain

A

Micrococcus

53
Q

Colonial on 5% sheep blood agar

A

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 (19 decks)

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