Infection and Drug Resistance (May 2022)

Minocycline Susceptibility and tetB Gene in Carbapenem-Resistant Acinetobacter baumannii in Taiwan

  • Yang JL,
  • Yang CJ,
  • Chuang YC,
  • Sheng WH,
  • Chen YC,
  • Chang SC

Journal volume & issue
Vol. Volume 15
pp. 2401 – 2408


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Jia-Ling Yang,1 Chia-Jui Yang,2,3 Yu-Chung Chuang,1 Wang-Huei Sheng,1 Yee-Chun Chen,1 Shan-Chwen Chang1 1Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan, Republic of China; 2Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan; 3School of Medicine, National Yang Ming Chiao Tung University, Taipei, TaiwanCorrespondence: Yu-Chung Chuang, Division of Infectious Diseases, Department of Internal Medicine, National Taiwan University Hospital, No. 7 Chung-Shan South Road, Zhongzheng Dist, Taipei, 100225, Taiwan, Republic of China, Tel +886 2 2312 3456 ext 65054, Fax +886 2 2397 1412, Email [email protected]: In this study, we evaluated the minocycline susceptibility rate in carbapenem-resistant Acinetobacter baumannii (CRAB) clinical strains, and the association between tetB 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. TetB 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 MIC50/90 was 4/16 mg/L. Ninety-seven (97%) strains carried tetB. All of the tetB-positive strains and 66.7% (2/3) of the tetB-negative strains were PK-PD non-susceptible. By statistical analysis, tetB carriage was significantly correlated with PK-PD non-susceptibility (P = 0.03) and a higher minocycline MIC (P = 0.02). The sensitivity and specificity of the tetB 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 tetB gene. Recognizing the minocycline MIC and tetB status may be essential when using minocycline to treat CRAB-related infections.Keywords: CRAB, minocycline PK-PD non-susceptibility, multidrug resistance, efflux