Minocycline Susceptibility and Gene in Carbapenem-Resistant in Taiwan.

PURPOSE

In this study, we evaluated the minocycline susceptibility rate in carbapenem-resistant (CRAB) clinical strains, and the association between carriage and minocycline susceptibility in CRAB.

PATIENTS AND METHODS

A total of 100 genetically unrelated CRAB clinical strains from bloodstream infection were randomly collected from a medical center in Taiwan. An argument for a new minocycline susceptibility breakpoint of 1 mg/L was suggested based on pharmacokinetic (PK) and pharmacodynamic (PD) studies. Strains with minocycline minimum inhibitory concentrations (MICs) of >1 mg/L were classified as PK-PD non-susceptible. carriage was detected by polymerase chain reaction (PCR).

RESULTS

Fifty-five (55%) CRAB strains were susceptible to minocycline according to the Clinical and Laboratory Standards Institute (CLSI) criteria, among which 98.2% (54/55) were PK-PD non-susceptible. The minocycline MIC was 4/16 mg/L. Ninety-seven (97%) strains carried . All of the -positive strains and 66.7% (2/3) of the -negative strains were PK-PD non-susceptible. By statistical analysis, carriage was significantly correlated with PK-PD non-susceptibility ( = 0.03) and a higher minocycline MIC ( = 0.02). The sensitivity and specificity of the PCR for predicting PK-PD non-susceptibility were 98% and 100%, respectively.

CONCLUSION

At our institute, most CRAB strains were PK-PD non-susceptible and most carried gene. Recognizing the minocycline MIC and status may be essential when using minocycline to treat CRAB-related infections.