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 AmpC beta-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. © 2017 Akadémiai Kiadó, Budapest

Characterization of antimicrobial resistance patterns of Klebsiella pneumoniae isolates obtained from wound infections

BACKGROUND: Multidrug resistance among ESBL producing isolates has limited the administration of proper antibiotics. It is therefore important to monitor the resistance patterns of Klebsiella pneumoniae isolates and provide infection control strategies to prevent nosocomial outbreaks. This study was aimed to determine antimicrobial resistance patterns of K. pneumoniae isolates obtained from wound infections of patients in Tehran, Iran. METHODS: Totally, 102 K. pneumoniae isolates were obtained from wound infections of patients in Tehran, Iran. Phenotypic ESBL and carbapenemase production was assessed using double-disc synergy test (DDST) and modified Hodge test (MHT), respectively. PCR was performed for the detection of ESBL, carbapenemase, quinolone and aminoglycoside resistance genes. RESULTS: Forty-six (45.1) and 23 (22.5) isolates, out of the 102 isolates, were phenotypically detected as ESBL and carbapenemase producers, respectively. The PCR results showed that 80/102 (78.4) and 51/102 (50) isolates possessed at least one of the assessed ESBL and carbapenemase genes, respectively. Quinolone resistance determinants (QRDs) and aac(6')-Ib genes were found amongst 50 (49) and 67 (65.7) isolates, respectively. Four isolates carried the blaTEM, blaSHV, blaCTX-M, qnrB, qnrS and aac(6')-Ib genes, simultaneously. CONCLUSION: Because of the presence of multiple resistance genes among some K. pneumoniae strains, antibiotic agents should be used with caution to preserve their efficacy in case of life-threatening infections