Detection of blaNDM-1 and blaOXA-23-like genes in carbapenem resistant Acinetobacter calcoaceticus-baumanii complex isolated from inpatients of Kathmandu Model Hospital, Nepal

Abstract

Abstract Background Acinetobacter calcoaceticus-baumannii (ACB) complex is a major nosocomial pathogen that is frequently involved in outbreaks of infection, occurring mostly in intensive care units. They have capacity to acquire resistance to various classes of antibiotics including carbapenems and hence emerged as one of the most common nosocomial pathogens of the present time. Methods This study was conducted to detect blaNDM-1, blaOXA-23-like, and blaOXA-24-like genes from carbapenem resistant Acinetobacter calcoaceticus-baumanii (CR-ACB) complex. This study was crossectional hospital-based study carried out in Kathmandu Model Hospital in which total of 992 representative inpatient samples were taken for the study and genetic works were performed in Centre for Health and Disease studies. Results Out of 992 samples, 43(4.33%) isolates were found to be ACB complex out of which 35 (81.4%) isolates were found to be carbapenem resistant. All CR-ACB complex were found sensitive towards polymixin B and colistin but tigecycline was effective in only 54.28% isolates. Thirty-three (94.28%) isolates gave positive MHT. Among 35 isolates of CR-ACB complex, 29(82.86%) isolates were positive for blaOXA-23-like gene and 12 (34.28%) isolates were positive for blaNDM-1 gene. However, all isolates were negative for blaOXA-24-like gene. Eleven (31.4%) of the isolates contained both blaOXA-23-like and blaNDM-1 genes which showed co-existence. Total 30 (85.7%) isolates were found to have carbapenemase genes. Conclusion Thus, the study showed that significant association between carbapenem resistance and genetic presence of carbapenemase genes although there are others parameters that are also responsible for carbapenem resistance.