FIRST REPORT OF COEXISTENCE OF AmpC BETA-LACTAMASE GENES IN KLEBSIELLA PNEUMONIAE STRAINS ISOLATED FROM BURN PATIENTS

Klebsiella spp. are among the most frequently isolated bacteria from burn wounds. These organisms are among the most important opportunistic pathogens, causing hospital-acquired and healthcare-associated infections worldwide. Limited information is available about prevalence of AmpC-producing Klebsiella pneumoniae from burn patients. Therefore, the aim of this study was to determine the characterization of AmpC beta-lactamase among K. pneumoniae isolated from burn patients. Samples were collected from wound specimens of patients with burn injury from a burn hospital in Tehran during 18 months (March 2015 to August 2016). For phenotypic detection of AmpC beta-lactamase, disk diffusion method with cefoxitin was used for screening, AmpC disk test and boronic acid inhibitor-based method were used as confirmatory tests. Polymerase chain reaction (PCR) was performed to screen all isolates with AmpC genes including ACCM, DHAM, EBCM, FOXM, MOXM, and CITM. Finally, PCR products were validated using sequencing. During this study, 102 isolates of K. pneumoniae were collected. Among these isolates, 52.9% suspected as AmpC producer by disk agar diffusion cefoxitin screening method. By confirmatory phenotypic methods, 19.6% of isolates considered as AmpC producer. Molecular analysis revealed 43.1% of cefoxitin-resistant isolates harbored at least one of the AmpC genes including CITM (22.5%), EBCM (21.5%), DHAM (7.8%), and FOXM (0.98%). In addition, 5.8% of isolates harbored two AmpC genes and 2.9% harbored three AmpC genes. In conclusion, K. pneumoniae is becoming a serious problem in burn patients. Accurate and precise methods and guidelines should be designed for detection of antibiotic-resistant mechanisms. Our data showed the high rate of AmpCbeta-lactamase among K. pneumoniae isolated from burn patients, which limit the treatment options. Therefore, the results of this study can provide evidence to help for appropriate treatment of burn patients.