Microbiology

Question 1

Septic patients given broad-spectrum antibiotics:

Answer 1

Amoxicillin
Gentamicin
Metronidazole

Question 2

PCR tests used for ?

Answer 2

Highly specific and sensitive to all microorganisms (bacteria, viruses, fungi, parasites)

Question 3

If gram-positive in chains =

Answer 3

Streptococci

Perform an agglutination assay

Question 4

Sensitivity vs resistance test

Answer 4

Disc diffusion

(+ sometimes there are e-tests for specific microorganisms)

Question 5

Sensitivity =

Answer 5

Trust your negatives

Question 6

Specificity =

Answer 6

Trust your positives

Question 7

Clearance of procalcitonin?

Answer 7

Renal

Question 8

Where is CRP produced?

Answer 8

Liver

Question 8

Where is procalcitonin (PCT) produced?

Answer 8

Lots of different cells

Question 9

High CRP but low PCT?

Answer 9

• Non-bacterial infection
• Post-surgical

Question 10

Infection is likely (scoring systems)

Answer 10

NEWS 5
(q-SOFA >2)
(SIRS >2)

Question 11

Important causes of gram-negative sepsis

Answer 11

Escherichia coli

Klebsiella, Serratia, Acinetobacter, Enterobacter (not to be confused with the gram-positive Enterococcus), Citrobacter (covered in GI and Renal)
Pseudomonas aeruginosa (covered in Resp, a bit in renal)
*Neisseria meningitides (covered in CNS)
Neisseria gonorrhoea

Question 12

H. influenzae gram stain

Answer 12

gram-negative coccobacillus

• generally aerobic but can function as a facultative anaerobe

Question 14

Macrolide

Answer 14

Mycin

Question 15

(Fluoro)quinolones

Answer 15

Floxacin

Question 16

Where does legionella invade and grow?

Answer 16

Alveolar macrophages

Question 17

Urinary antigen test for legionella - which serogroup?

Answer 17

L. pneumophila 1

(accounts for 80% of cases)

Question 18

Staph epidermis in the presence of prosthetic material

What antibiotic?

Answer 18

Vancomycin

(generally flucloxacillin resistant)

Question 20

Staphylococci vs streptococci

Answer 20

Staph = clusters
Strep = chains

Question 21

Plasma used for detection of coagulase

Answer 21

Rabbit coagulase plasma

Question 22

Criteria used to assess likelihood of endocarditis

Answer 22

Duke’s criteria

Question 23

Alpha haemolytic streptococci in suspected endocarditis =

Answer 23

Strep viridans

(could also be Strep pneumoniae but this is less likely)

Answer 24

Streptococcus pyogenes aka Group A beta haemolytic strep
- Pharyngitis, skin
- Immunologic sequelae

Streptococcus agalactiae aka Group B (beta) haemolytic strep
- Pregnancy and neonates

Streptococcus pneumoniae
- Otitis, pneumonia, meningitis

Viridans streptococcal group
- Endocarditis, abscesses

Streptococcus bovis renamed Streptococcus gallollyticus subsp. gallolyticus
- Endocarditis
- GI associations

Question 25

Enterococcus antibiotic of choice

Answer 25

Amoxicillin

• Vancomycin if penicillin-resistant

Question 26

Define MIC (minimum inhibitory concentration)

Answer 26

Measure of the potency of the drug against a given pathogen

concentration of drug required to kill 99.9% of organisms during 18 to 24 hours

Question 27

How to measure MIC?

Answer 27

Broth dilution method

Question 28

NEWS >5 + suspected infection =

Answer 28

SEPSIS

Do Sepsis 6