Identification and Characterization of OXA-48 Carbapenemase- Producing Enterobacteriaceae Clinical Isolates in Baghdad


Background: Enterobacteriaceae is the most frequent Gram-negative pathogens that are accountable for many serious infectious diseases. The emergence and widespread carbapenem-resistant Enterobacteriaceae have increased dramatically and have become a burden on public health with increasing challenge in treatment with classical antibiotics.Objectives: The goal of this research was to detect of OXA-48 carbapenemaseproducing Enterobacteriaceae clinical isolates using a new in vitro phenotypes technique“OXA-48 K-SeT assay”.Methods: A total of 40 Enterobacteriaceae strains was involved in this investigation. Antibiotics susceptibility rates were carried out by modifying Kirby-Bauer’s disk diffusion technique. Biochemical tests were performed using the API 20 E kit. Identification of OXA-48 carbapenemase was tested by OXA-48 K-SeT assay and modified Calgary biofilm method were used for detection of biofilm formation.Results: The majority of Enterobacteriaceae isolates were obtained from urine samples 23 (57.5%) followed by sputum and wound exudate samples 6 (15%), 5 (12.5%) respectively. The prevalence of infection with E. coli and K. pneumoniae was significant among age groups of 40 -59 years old (P <0.001), and patients with age below twenty or over sixty years old showed lower susceptibility to infection withEnterobacteriaceae. The strains of k. pneumoniae obtained from urine samples exhibited a strong propensity to develop biofilms and it showed an excellent biofilm propensity score, whereas E. colistrains showed a lower propensity to form biofilm. In addition, K. Pneumonia was displaying a predisposition to resistant to OXA-48 carbapenemase with 7 (17.5%) positive for OXA-48 K-SeT, while only 4 (10%) E. coli exhibit positive results for OXA-48 K-SeT.The most OXA-48-positive and OXA-48-negative of Enterobacteriaceae isolates showed markedly resistance to beta-lactamase inhibitor combination (amoxicillin-clavulanate and piperacillin-tazobactam) with different resistance rates were noted against cephalosporin groups (ceftazidime, cefotaxime, cefepime, and cefoxitin) and less resistance to monobactam groups (aztreonam) were observed, while no resistance was observed against colistin. The higher levels of antibiotic resistance correlated dramatically with increase biofilm-producing of Enterobacteriaceae, regardless of types of antibiotics (β-lactam and non- β-lactam antibiotics).Conclusion: The findings of this study show that the OXA-48 K-SeT assay were exact phenotypic method and significant test for direct detection of OXA-48-producing Enterobacteriaceae. This study found clearly correlating of biofilm formation and increased level of antibiotic resistance in Enterobacteriaceae isolates. The quick recognition and confirmation of carbapenemases resistance in these bacteria is important for proper choice of antibiotics and avoidance multidrug-resistant pathogens.