Detection of Antibiotic Resistance genes of Multidrug Resistance Enterobacter Cloacae and Enterobacter Aerogenes Isolated from the Patients of Dhaka Medical College Hospital

Author(s): Azmeri Haque, Nafisa Jabin Mishu, H M Khaleduzzaman, S M Shamsuzzaman, Avizit Sarker, MD Zabed Ahmed Mitu, Rizwana Zaman, Rubaiya Binte Kabir, MD Asaduzzaman

Emergence of multidrug resistant strains of Enterobacter spp. has a potential threat because these strains were responsible for high morbidity and mortality in recent years due to nosocomial infection in health care settings. Due to shortage of new effective antibiotic, old drug like fosfomycin recently reintroduced in human medicine for the treatment of multi drug resistant (MDR) gram negative bacteria. Sample size was 360. We collected different samples like urine, wound swab, endotracheal aspirate and blood from microbiology lab of Dhaka medical college. Organisms were isolated and identified by culture, gram staining and biochemical tests. Further tests were done only on common Enterobacter species. Antibiotic susceptibility tests were performed by disc diffusion technique. Polymerase chain reaction (PCR) was used to identify different colistin resistance genes (mcr-1 and mcr-2,) fosfomycin resistance genes (fosA, fosA3, fosA4) and carbapenem resistance genes (blaKPC, blaIMP, blaVIM and blaOXA-48 / blaOXA181). Sequencing of fosA4 gene was done. Present study observed the presence of fosfomycin resistance gene of multidrug resistant (MDR) Enterobacter spp. Among the 360 samples 66.11% yielded culture positive results and out of the culture positive samples 10.53% were Enterobacter spp. Among Enterobacter spp. 82.76% E. cloacae and 17.24% E. aerogenes were identified by biochemical tests. Among the 17.24% isolated E. aerogenes, 100% were resistant to amoxiclav and cefoxitin and ceftazidime, 80% were resistant to ciprofloxacin and amikacin, 60% were resistant to piperaicillin-tazobactam, cefuroxime and ceftriaxone, 40% were resistant to aztreonum, cefepime and fosfomycin, 20% were resistant to imipenem and colistin but none were resistant to tigecycline. Among the fosfomycin resistant Enterobacter spp. 80% were positive for fosA gene, 50% were positive for fosA4 gene, 50% were positive for fosA5gene. Sequencing of PCR product of fosA4 gene showed multiple point mutations. So, Antimicrobial susceptibility testing must be done before prescribing antibiotics due to the high rates of resistance of Enterobacter spp. to multiple antibiotics.