Staphylococcus

Question 1

What type of bacteria are characterized as Gram positive cocci?

Answer 1

Staphylococcus

Staphylococcus is a genus of bacteria that are spherical in shape and stain positive in the Gram staining procedure.

Question 2

Are Staphylococcus bacteria motile or non-motile?

Answer 2

Non-motile (Atrichous)

Atrichous means lacking flagella, which are structures that enable motility.

Question 3

What type of spores do Staphylococcus bacteria form?

Answer 3

Non-sporing

Non-sporing indicates that these bacteria do not produce spores, which are typically resistant structures formed under adverse conditions.

Question 4

What is the oxygen requirement for Staphylococcus bacteria?

Answer 4

Facultative anaerobes

Facultative anaerobes can grow in the presence or absence of oxygen.

Question 5

What is the salt tolerance of Staphylococcus bacteria?

Answer 5

Can grow in 7-10% Salt

This characteristic indicates their ability to thrive in high-salinity environments.

Question 6

What biochemical reaction is Staphylococcus known for?

Answer 6

Catalase positive

Catalase positive means that these bacteria produce the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen.

Question 7

Is Staphylococcus oxidase positive or negative?

Answer 7

Oxidase negative

Oxidase negative indicates that these bacteria do not produce the enzyme oxidase.

Question 8

What is the culture requirement for Staphylococcus bacteria?

Answer 8

Non fastidious

Non fastidious means that they do not have complex nutritional requirements and can grow on a variety of media.

Question 10

Most Gram -vr bacteria grow on MacConkey agar except

Answer 10

Staph aureus and Enterococcus

Question 11

Selective media for staph aureus

Answer 11

Salt/salt milk agar
LUDLAMs medium

Question 13

M/c site of stap aureus (carriage)

Answer 13

Nose
Other sites : Hair, oropharynx, vagina, skin

Question 14

M/c mode of spread of mrsa in hospital

Answer 14

Hands of healthyworkers

Question 16

Virulence of staph aureus in cell wall that is anti phagocytic and anti complementary

Answer 16

Protein A
Used in co agglutination for soluble antigen

Question 17

Hemolysins in staph and their specialties
Alpha, beta, gamma

Answer 17

Alpha : Paradoxical reactivation (reactivation at 80°, deactivated at 100°)

Beta : hemolysis at 37°, completed at 4°C

Gamma: Synergohymenotrophic toxins

Question 19

Hot cold phenomenon is shown by

Answer 19

Beta hemolysin toxin

Question 20

Performed toxins are sene in

Answer 20

Staph aureus
Bacillus (chinese fried food)
Botulinum

Question 21

Panton Valentine leukocidin toxin seen in

Answer 21

Staph aureus

Question 22

Epidermolytic toxins cause
EF A and EF B

Answer 22

Staphylococcal scaldel skin syndrome (ssss)
or Ritters disease

Question 23

Proteolysis of which protein and which layer of skin causes ssss

Answer 23

Desmoglein 1
In stratum granulosum

Question 24

MSSA antibiotics choice
MRSA
Strep TSS

Answer 24

Nafcillin/oxacillin/cloxacillin
Vancomycin
Pencillin + Clindamycin

Question 25

Non menstrual TSS is

Answer 25

Caused by S pyogenes or S.aureus

Question 26

M/c of ventilator associated and hosp acquired pneumonia

Answer 26

S.aureus

Question 28

Most common cause in children of

Answer 28

Penumonia in cystic fibrosis

Question 29

Beta lactam resistance is by MRSA resistance is bu

Answer 29

1. Beta lactamase encoded by resistance plasmids 2. MRSa SCC mec -----> contains mecA gene ----> encoded altered transpeptidase

Question 30

Gold standard for mecA gene detection

Answer 30

PCR

Question 31

Vancomycin resistance

Answer 31

Normal vancomycin : binds to cell wall precursors D ala D ala, inhibit cell wall synthesis Resistance: Altered cell wall precursors (d ala d ala)

Question 32

Drug of choice for s.epidermidis

Answer 32

Vancomycin ( Bactermia in IV catheterization)

Question 34

S. Saprophyticus pathogenic city

Answer 34

UTI in sexually active women

Question 35

Slide coagulase positive Slide coagulase negative

Answer 35

+ : S.aureus - : S.epidermidis

Question 36

Which strains of Coagulase negative Staph are resistant to NOVOBIOCIN

Answer 36

S.saprophyticus S.nylosus

Question 37

Most pathogenic CoNS

Answer 37

Staph.epidermidis

Question 38

Most Gram negative grows in MacConkey agar except

Answer 38

Staph aureus and Enterococcus

Question 39

Selective media for Stap aureus

Answer 39

Salt/ salt milk agar, LUDLAMS medium

Question 40

M/c mode of spread of Stap aureus or MRSA in hospitals

Answer 40

Hands of healthcare workers