Determination of Carbapenem Resistance in Gram-Negative Bacteremia in the Burn Intensive Care Unit

Abstract

Introduction: Gram-negative sepsis constitutes a significant cause of mortality and morbidity in the burns intensive care unit (BICU). In the current era of a global antibiotic resistance crisis, it is imperative to monitor the geographical distribution of carbapenem-resistant microorganisms. Therefore, we aimed to determine the resistance rates of gram-negative microorganisms and the mechanisms that cause carbapenem resistance in the BICU. Materials and Methods: From February 2015 to February 2016, we conducted a patient follow-up in the BICU of our hospital. Carbapenem-resistant gram-negative bacteria were identified in the blood cultures of 39 patients. Forty-nine episodes of bacteremia in 39 patients were included in this study. The study assessed the relationship between patients’ demographic characteristics, signs associated with burn, abbreviated burn severity index (ABSI), and acute physiology and chronic health evaluation (APACHE-II) score with mortality. The carbapenemase enzyme was identified using genotypic methods. Carbapenemase gene regions in DNA samples were investigated by multiplex polymerase chain reaction (PCR). Results: Out of the total cases, 77% were male patients with a median age of 36 (1-89) years. Flame burn was detected as the most common. The mortality rate in this study was 43%. Statistically significant relationships were identified between ABSI and APACHE-II scores with mortality. Of the blood culture isolates, 27 (55%) were Acinetobacter baumannii, 17 (34%) Pseudomonas aeruginosa, three (6%) Klebsiella pneumoniae, one (2%) Enterobacter cloacae, one (2%) Proteus vulgaris. OXA-23 enzyme was detected in all of the A. baumannii strains. KPC enzyme was detected in one of the P. aeruginosa strains. NDM was found in two of the K. pneumoniae strains, and NDM-1 and OXA-48 enzymes were detected together in one. NDM enzyme was detected in the E. cloacae strain. Conclusion: In this study, it was observed that A. baumannii strains are the most prevalent agents causing bacteremia in the burns intensive care unit (BICU). While the OXA-23 gene was detected in all of the A. baumannii strains, the Carbapenemase enzyme was not detected in 94% of the P. aeruginosa strains. It is anticipated that these data will guide the selection of antibiotics in the burns intensive care unit (BICU).

Keywords

• antibiotic resistance
• gram-negative bacteria
• carbapenemase