Contribution of OqxAB Efflux Pump in Selection of Fluoroquinolone-Resistant Klebsiella pneumoniae

Abstract

The role of OqxAB efflux pump in Klebsiella pneumoniae was investigated in correlation with ciprofloxacin exposure. K. pneumoniae SE23 and K. pneumoniae SE191 were isolated from urinary tract infections and were analyzed in this study. Each carried oqxAB resistance determinant and exhibited ciprofloxacin MIC of 0.06 and 0.5 mg/L, respectively. Tested strains were initially exposed to their ciprofloxacin MIC values for 24 hours. Later on, the ciprofloxacin exposition has been increased to a daily 1, 2, 4, and to a final 8 mg/L. Total cellular RNA was extracted at 30, 60, 90, and 120 minutes of initial exposure and after every 24 hours. Quantitative reverse-transcriptase PCR was performed from each RNA sample. Mutation in gyrA and parC genes was analyzed in each strain and multilocus sequence typing (MLST) was performed. Ciprofloxacin exposure selected resistant strain from K. pneumoniae SE191; by contrast, K. pneumoniae SE23 was not adjustable to the increasing ciprofloxacin concentrations. During initial exposure, both oqxA and oqxB expression remained low (2−ΔCt = 1-2.03). However, increasing ciprofloxacin promoted oqxB expression as it reached fold increase of 15.8–22.8, while oqxA expression was maintained (2−ΔCt = 2-2.15). An amino acid substitution Ser83Tyr in gyrA was detected in K. pneumoniae SE191, but no additional mutations occurred as consequence to ciprofloxacin exposure. MLST identified K. pneumoniae SE191 as ST274, while K. pneumoniae SE23 belonged to the novel ST2567. Ciprofloxacin concentration-dependent upregulation of oqxAB efflux pump in K. pneumoniae is clonally related and contributes to selection for higher level of fluoroquinolone resistance.

Molecular patterns of clinically important fluoroquinolone resistance in multidrug-resistant Klebsiella pneumoniae isolates during nosocomial outbreaks in Shanghai, PR China

“…OqxAB, firstly identified on olaquindox resistance plasmids (pOLA52) in Escherichia coli of veterinary origin, is now widely distributed in diverse clinical MDR-KP genomes from humans [24]. Here, OqxAB pumps were presented in almost all isolates regardless of ciprofloxacin susceptibility, the bla-sequences of which varied, correlating with specific STs as a consequence of the transmission and evolution of the original sequence (oqxA1B1; pOLA52) from isolates of ST11, a finding that was consistent with the observation that ciprofloxacin concentration-dependent upregulation of OqxAB efflux pump in K. pneumoniae is clonally related [43]. Mobile quinolone pump, QepA, has not been detected in any hospital in PR China at present [13,33].…”

“…pneumoniae [3, 46, 47]. AcrAB and OqxAB, two resistance–nodulation–division family pumps, made differential contributions to MDR and virulence [43, 48, 49]. In the absence of AcrAB, gyrase mutations fail to produce clinically relevant levels of resistance [50].…”

“…Mutations that result in altered OM permeability have also been shown to generate a fluoroquinolone resistance phenotype in K. pneumoniae [3,46,47]. AcrAB and OqxAB, two resistance-nodulation-division family pumps, made differential contributions to MDR and virulence [43,48,49]. In the absence of AcrAB, gyrase mutations fail to produce clinically relevant levels of resistance [50].…”

Plethora of Resistance Genes in Carbapenem-Resistant Gram-Negative Bacteria in Greece: No End to a Continuous Genetic Evolution

“…The presence of genes oqxA and oqxB might also have contributed to the fluoroquinolone resistance profile of 26 K. pneumoniae. The plasmidic efflux pump OqxAB confers resistance to multiple agents, including fluoroquinolones as well as biocides, and has been shown to play a role in the selection of fluoroquinolone resistance in different K. pneumoniae clones [42,43].…”

Efflux pump activity, biofilm formation and antibiotic resistance profile of Klebsiella spp. isolated from clinical samples at Lagos University Teaching Hospital

“…Thus it could be asserted that active efflux pump played a role in the observed level of antibiotic resistance. Szabo et al [22] and Maurya et al [23] reported the role of efflux pump in quinolone and β-lactam antibiotic resistance in Klebsiella pneumoniae strains isolated from clinical samples in Hungary and India respectively. Klebsiella spp.…”