Applied Microbiology and Beneficial Microbes

Biography

Biography: Juhee Ahn

Abstract

The multidrug resistance in K. pneumoniae is primarily mediated by the production of different classes of b-lactamases. The relationship between b-lactamase production and resistance phenotype is essential to understand the resistance mechanisms in K. pneumoniae. However, there is still a lack of information on the phenotypic and genotypic antibiotic resistance profiles in association with the classes of b-lactamases in K. pneumoniae. Therefore, the aim of this study was to evaluate the antibiotic susceptibility and b-lactamase production in ciprofloxacin-induced and clinically-isolated antibiotic-resistant K. pneumoniae strains, based on the interaction between b-lactamases and b-lactamase inhibitors. The antibiotic susceptibility and β-lactamase activity of K. pneumoniae strains, including antibiotic-sensitive K. pneumoniae (KP^WT), ciprofloxacin-induced resistant K. pneumoniae (KP^CIP), and clinically isolated K. pneumoniae strains (KP^CI237, KP^CI263, and KP^CI272), were determined in the absence and presence of β-lactamase inhibitors (BLI 489, sulbactam, clavulanate, and tazobactam). All strains were highly resistant to ampicillin in the absence of b-lactamase inhibitors (MIC≥512 mg mL^-1). In the presence of clavulanate, the MICs of ampicillin and piperacillin against KP^WT were decreased by >64-fold and 4-fold, respectively. The resistance of KP^CI263 to cefotaxime, ceftazidime, ceftriaxone, and piperacillin were increased in the presence of BLI-489. The antibiotic susceptibilities KP^CI237 to b-lactams were not noticeably changed in the presence of β-lactamase inhibitors (clavulanate, sulbactam, and tazobactam). KP^WT, KP^CIP and KP^CI272 were positive for bla_SHV, bla_AmpC, and bla_FOX/MOX, KP^CI237 for bla_SHV and bla_AmpC, and KP^CI263 for bla_SHV and bla_OXA-48. The antibiotic susceptibility corresponded well with the results obtained from dual disc diffusion assay, which was in good agreement with the b-lactamase production. The results provide useful information for understanding the resistance phenotypes in association with b-lactamase production.