Overview Of Microbiology And Infectious Disease Introduction

Question 1

How will gram positive bacteria stain?

Answer 1

Purple

Question 2

How does gram negative bacteria stain

Answer 2

Red

Question 3

What are the gram positive bacteria in clusters

Answer 3

Staphylococcus

Question 4

What are the common staphylococci and where are they most commonly found

Answer 4

1. Staph aureus
   *nasal, skin flora, mucus membranes
2. S. Epidermidis
   *skin flora, mucus membrane
3. S. Saprophyticus
   *genital, perineum flora

Question 5

How will each straphylococci react to a a coagulate test

Answer 5

+ staph aureus
- s.epidermidis, s, saprophyticus

Question 6

What are gram positive bacteria in pairs and chains

Answer 6

Streptococci

Question 7

What are the alpha hemolytic streptococci and where are they found?

Answer 7

1. Viridians streptococci
2. Strep pneumonia (diplococci)
   *colonize in oral cavity, URT

Question 8

What are the beta hemolytic streptococci and where are they found?

Answer 8

1. S. Pyogenes (group A)
2. S. Agalactiae (group B)
   *GBS vaginal / GI flora

Question 9

What are y-hemolytic streptococci and where are they found?

Answer 9

1. Enterococci (E. Faecalis E. Faecium)
   *GI flora

Question 10

What are the gram positive bacteria bacilli

Answer 10

1. Listeria
2. Corynebacterium
3. Bacillus

Question 11

What are the gram positive anaerobes

Answer 11

1. Peptostreptococcus
2. Clostridium spp.
3. Propionibacterium
4. Lactobacillus

Question 12

What is the coagulase test used for ?

Answer 12

1. Used to differentiate S.aureus from coagulase negative staphylococci
   *S. Aureus (+)
   *S. epidermidis (-)
   *S. Saprophyticus (-)

Question 13

Wha is MSSA/MSSE?

Answer 13

Methicillin susceptible (staph aureus / epidermidis)
1. Cant destroy structurally resistant B-lactams, and can be neutralized by B-lactamase inhibitors

Question 14

What is MRSA / MRSE?

Answer 14

Methicillin-resistant
1. Changes in the penicillin binding proteins, the target site of B lactams, coded by the mcA gene

Question 15

What is MLSb resistant

Answer 15

Macrolide / Lincosamide / Streptogramin B resistant
1. One of macrolide resistance mechanisms in staphylococci is ‘methylation of 23s rRNA’
2. Results in cross-resistance to macrolides, Clindamycin, and type B streptogramin

Question 16

What is the problem with inducible MLSb resistance?

Answer 16

1. Staphylococci with inducible MLSb resistance will be shown as resistant to macrolides but susceptible to Clindamycin

Question 17

Failure to identify inducible MLSb resistance can lead to what?

Answer 17

1. Failure of therapy

Question 18

How to test for inducible resistance Clindamycin

Answer 18

D Test
1. Used to test S.aureus isolates that appears erythromycin resistant and Clindamycin susceptible during C&S testing
2. + test means the presence of Clindamycin resistance to staph aureus

Question 19

How to differentiate the streptococci

Answer 19

1. Hemolysis on blood agar
   *alpha beta, y-hemolytic
2. Type of cell wall carbohydrates
   *A, B, C, D

Question 20

What are the different type of alpha hemolytic streptococci and how will they look on a blood agar

Answer 20

1. Viridians streptococci
   *normal mouth flora
   *can cause oral/dental infection, endocarditis
2. S. Pneumonia
   *encapsulated virulent
   *colonize in the URT

**partial hemolysis
**looks greenish on blood agar

Question 21

What are the different types of beta hemolytic streptococci and how will it look on a blood agar

Answer 21

1. S. Pyogenes (group A strep, GAS)
   *virulent
2. S. Agalactiae (group B strep, GBS)
   *female vaginal a/o GI flora

**complete hemolysis
**clear area on red plate

Question 22

What are the Y-hemolytic streptococci and how will they look on the blood agar

Answer 22

1. Enterococci (E. Faecalis MC, E. Faecium LC)
   *normal GI flora
   *opportunistic tend to be in patients with co-morbidities
   *no hemolysis
   *blood agar stays red

Question 23

Which Y-hemolytic streptococci is more severe or resistant

Answer 23

E. Faecalis
*more common
*less resistant
E. Faecium
*less common
*more resistant

Question 24

What are different organisms of the clostridium spp

Answer 24

1. C. Perfringes
   *gas gangrene
   *cellulitis
2. C. Difficile
   *diarrhea
   *colitis

**gram positive anaerobes (use soap and water)

Question 25

What are the gram negative diplococci

Answer 25

1. Neisseria meningitidis
2. Neisseria gonorrhea

Question 26

What are the gram negative bacilli (lactose fermenter)

Answer 26

+ oxidase
1. Pasteurella
- oxidase
1. E. Coli, klebsiella
2. Enterobacter
3. Citrobacter

Question 27

What are the gram negative bacilli (non-lactose fermenter)

Answer 27

+ oxidase
1. Pseudomonas spp
- oxidase
1. Proteus spp
2. Acinetobacter spp

Question 28

What are the gram negative coccobacilli

Answer 28

1. Haemophilus influenza
   *colonize in URT

Question 29

What are the gram negative anaerobes

Answer 29

1. Bactericides fragilis
   *GI flora

Question 30

Which gram negative diplococci causes STIs and which causes meningitis

Answer 30

N. Gonorrhoeae
*STI
N. Meningitidis
*common cause of meningitis outbreak

Question 31

What organism belong to the Enterobacteriaceae family

Answer 31

1. E.coli (MC GN pathogen)
   *MC aerobe of the GI tract
   *flagella allow for movement
   *primary cause of UTI\

Question 32

What are other common enterbacteriacea species

Answer 32

1. Klebsiella pneumonia (2nd MC GN pathogen)
2. Enterobacter spp (4th MC GN pathogen)
3. Proteus spp (5th MC GN pathogen)