The following is the summary of “Comparison of carbapenem minimum inhibitory concentrations of Oxacillin-48-like Klebsiella pneumoniae by Sensititre, Vitek 2, MicroScan, and Etest” published in the December 2022 issue of clinical microbiology and infections by Nana, et al.
This laboratory investigation aimed to evaluate the sensitivity and specificity of the carbapenem minimum inhibitory concentration (MIC) for Klebsiella pneumoniae isolates produced by the Sensititre, Vitek 2, MicroScan WalkAway plus, and Etest. In addition, a convenience sample of 82 deduplicated blood culture OXA-48-like K. pneumoniae isolates was analyzed for categorical agreement for ertapenem, meropenem, and imipenem, as well as the proportion of isolates with MICs ≤8μg/mL and the MIC50/MIC90 for meropenem and imipenem.
Etest had a higher percentage of ertapenem-susceptible isolates (19/82) than Sensititre/Vitek (0%; 0%) and MicroScan (2.4%; 2.4%) (all P<0.001). Etest’s percentage of meropenem-susceptible isolates (31/82, 37.8%) was higher than Sensititre/percentage Vitek’s (19/82, 19.5%) (P=0.015). When comparing Sensititre (9/82, 11%) and Vitek (8/82, 9.8%) to MicroScan (27/82, 32.9%), there were significant differences (P=0.001 and P<0.001, respectively), when comparing Sensititre and Vitek to Etest (45/82, 54.9%), there were significant differences (P<0.001 and P<0.001, respectively); and when comparing MicroScan to Etest, there Both Sensititre and Vitek had considerably higher rates of isolates with meropenem MICs 8 g/mL compared to Etest (58.5 and 85.4%, respectively; P<0.001).
The MIC for meropenem and imipenem at which 50% of isolates were inhibited was found to be twofold and fourfold higher, respectively, on the Sensititre and the Vitek, compared to the MicroScan and the Etest. Carbapenem minimum inhibitory concentration (MIC) values showed substantial variation among the four techniques for OXA-48-like carbapenemase-producing Enterobacterales isolates. Labs must verify the performance features of their MIC methods for the most common Enterobacterales type generating carbapenemases to improve the precision of their carbapenem reporting.
Source: sciencedirect.com/science/article/abs/pii/S1198743X22003378
