To perform the CIM, a suspension was made by suspending a full 10 μl inoculation loop of culture, taken from a Mueller-Hinton or blood agar plate in 400 μl water. Subsequently, a susceptibility-testing disk containing 10 μg meropenem (Oxoid Ltd, Hampshire, United Kingdom) was immersed in the suspension and incubated for a minimum of two hours at 35°C. After incubation, the disk was removed from the suspension using an inoculation loop, placed on a Mueller-Hinton agar plate inoculated with a susceptible E. coli indicator strain (ATCC 29522) and subsequently incubated at 35°C. Inoculation of the Mueller-Hinton agar plate with the indicator strain was done with a suspension of OD595 1.25 (correlates with a McFarland value of 0.5) streaked in three directions using a sterile cotton swab. If the bacterial isolate produced carbapenemase, the meropenem in the susceptibility disk was inactivated allowing uninhibited growth of the susceptible indicator strain. Disks incubated in suspensions that do not contain carbapenemases yielded a clear inhibition zone. If results are required within the same day, they can be read after six hours, but within the setting of our laboratory, we prefer reading results after overnight incubation