Prevalence of tigecycline resistant multidrug resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex from a tertiary care hospital in Nepal

Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex is an important nosocomial pathogen. Rapid development of resistance to multiple drugs limits the therapeutic options for the treatment of infections by ACB complex. The current study aimed to find the prevalence of ACB complex and know the antibiogram of these clinical isolates including the rate of multidrug resistance (MDR) and the in vitro activity of tigecycline against these isolates. This study was conducted from January to August, 2015. Of the 1,196 bacteria isolated from 10,950 clinical specimen, 150 (12.5%) were ACB complex. MDR-ACB complex were 71.3% of which 73.3% were from inpatient source. Resistance rates for ceftazidime 81.3%, ampicillin/sulbactam 56.7%, amikacin 56.7%, ciprofloxacin 68.7%, imipenem 47.3%, piperacillin 80.7% and piperacillin/tazobactam 68% were seen. Almost all ACB complex were sensitive to polymixin B and 98% to colistin. However, adopting the breakpoints recommended by the US FDA for Enterobacteriaceae, the resistance rate for tigecycline was 37.3%. Thus the present study provides valuable information regarding the very high prevalence of ACB complex in our hospital; the alarming number of MDRACB complex and the worrisome finding of comparatively high resistance rate to the latest drugtigecycline.