Anti-microbials 2

Question 1

define minimum inhibitory concentration? MIC

Answer 1

how much abx is needed to inhibit growth of organism is a test tube

Question 2

drugs can have different patterns of activity.

Concentration-dependent killing and Prolonged persistent effects are examples of which type of activity?

what would then be the goal of therapy?

Answer 2

type 1

Maximize concentrations

Question 3

drugs can have different patterns of activity.

Time-dependent killing andModerate to prolonged persistent effects are examples of which type of activity?

what would then be the goal of therapy?

Answer 3

Type 3

Maximize amount of drug

Question 4

Time-dependent killing and Minimal persistent effects

Answer 4

Type 2

Maximize duration of exposure

Question 5

put these in order of length of treatment course from longest to shortest:

Gp A Streptococcal pharyngitis
N. meningitidis meningitis
Bacterial endocarditis
Simple cystitis (in women)
Acute osteomyelitis (adult)

Answer 5

Acute osteomyelitis (adult)                  6wks
Bacterial endocarditis				4-6 weeks

Gp A Streptococcal pharyngitis 10 days
N. meningitidis meningitis 7 days
Simple cystitis (in women) 3 days

Question 6

rx for Skin Infections i.e. cellulitis, wound infections and impetigo?

Answer 6

Flucloxacillin (unless penicillin allergy or MRSA)

Question 7

what is iGAS ?

what is another name?

Answer 7

invasive group A strep
invasive i.e bacteraemia

aka toxic shock syndrome

Question 8

treatment for iGAS/ toxic shock syndrome?

Answer 8

Surgical debridement !

protein synthesis inhibitors - Clindamycin !

IVIG !

Question 9

what is the Eagle Effect?

Answer 9

the relative lack of efficacy of beta-lactam antibacterial drugs on infections having large numbers of bacteria.

Question 10

what is the mechanism behind the eagle effect

Answer 10

Penicillin is bactericidal

works by inhibiting cell wall synthesis - only occurs when bacteria are actively replicating

In extremely high bacterial burden (such as with Group A Strep), bacteria may be in the stationary phase of growth.

since no bacteria are actively replicating (presumably due to nutrient restriction) penicillin has no activity

Question 11

rx for Pharyngitis (sore throat) ?

Answer 11

Benzyl penicillin x 10 days

Question 12

rx for Community-acquired pneumonia (mild)

Answer 12

amoxicillin

Question 13

rx for Community-acquired pneumonia (severe)?

Answer 13

Co-amoxiclav & clarithromycin

Question 14

Main pathogens causing Bacterial Meningitis?

rx?

Answer 14

N. Meningitidis
S. pneumoniae

Ceftriaxone (+/- amoxycillin if Listeria likely)

Question 15

Bacterial Meningitis rx in babies less than 3 months?

Answer 15

: Cefotaxime PLUS Amoxicillin (to cover for listeriosis)

Question 16

reasons for penicillin resistance in Neisseria meningitidis ?

Answer 16

there is production of altered forms of one of the penicillin-binding proteins. PBP

Question 17

rx for Simple cystitis (community) ?

Answer 17

Trimethoprim x 3 days

Question 18

rx for Hospital-acquired UTI (commonest type of HAI):

Answer 18

Co-amoxiclav

cephalexin

Question 19

1st and 2nd line for severe c diff infection?

Answer 19

1st - p.o. metronidazole

If above fails, use p.o. vancomycin