Detection of In vitro Antibiotic Activity

Minimum Inhibitory Concentration (MIC) Assay - The MIC assay is a technique used to determine the lowest concentration of a particular antimicrobial needed to inhibit visible growth of bacteria. This assay is typically performed on planktonic (free floating) bacterial cells. MIC is determined by broth microdilution followed by inoculation onto agar plates for enumeration.

Minimal bactericidal concentration (MBC) - The MBC is the lowest concentration of antimicrobial required to kill an organism. To determine the MBC, cultures are incubated with serial dilutions of the compound(s) of interest, inoculated onto agar plates and enumerated. A colony count that represents 0.1% (99.9% reduction) of the original inoculum is considered as MBC.

Minimal doubling time/growth curve (MDT) - Additional testing could include the performance of a MDT of the strains in the presence or absence of the compound.

Bacteria currently available for testing (additional bacterial species can be acquired for purposes of individual interests):

Bacterial species

Number of isolates available

Details

Methicillin-Sensitive Staphylococcus aureus

19

Clinical and standard laboratory strains including 1 isogenic couple

Methicillin-Resistant Staphylococcus aureus

10

Clinical and standard laboratory strains including 2 isogenic couples

Pseudomonas aeruginosa

12

Clinical strains

Acinetobacter baumannii

20

Clinical strains

Enterobacter aerogenes

1

Clinical strains

Enterobacter cloacae

6

Clinical strains including ESBL, MDR, AMPC

Streptococcus pneumoniae

4

Clinical strains

Moraxella catarrhalis

3

Clinical strains