THE EXPRESSION OF GENES ADEB AND ADEJ IN PATIENTS RESISTANT TO DRUG TIGECYCLINE

Objective: To investigate the effect of overexpression of efflux pump genes adeB and adeJ on the sensitivity of tigecycline resist-ance in carbapenems-resistant Acinetobacter baumannii strains. Methods: A total of 137 strains of meropenem-and imipenem-resistant Acinetobacter baumannii isolates from in-patient samples from our hospital within the period May 2016 to November 2017 were se-lected. The ATCC25922 E. coli quality control strain was used to determine the minimal inhibitory concentrations (MIC) of tigecycline against Acinetobacter strains, with broth microdilution method and efflux pump inhibition experiments. The relative expression levels of adeB and adeJ, were determined with RT-PCR, and their differences were analyzed. Results: A total of 137 strains of carbapenems-resistant Acinetobacter baumannii were collected. They comprised 25 (18.25 %) tigecycline non-susceptible A. baumannii (TNAB) strains and 112 (81.75 %) tigecycline-susceptible A. baumannii (TSAB) strains. After exposing the strains to efflux pump inhibitors, the MIC of tigecycline non-susceptible A. baumannii was significantly decreased (p< 0.05). There were no statistically significant differences between frequencies of adeB and adeJ between tigecycline non-susceptible A. baumannii strains and tigecycline susceptible A. baumannii strains (p> 0.05). However, the relative expression levels of adeB and adeJ in tigecycline-susceptible A. baumannii strains were lower than those in the tigecycline non-susceptible A. baumannii (p< 0.05). Conclusion: Overexpressions of efflux pump genes adeB and adeJ reduce the sensitivity of tigecycline resistance in carbapen-emsresistant Acinetobacter baumannii strains.