Influence of induced ciprofloxacin resistance on efflux pump activity of Klebsiella pneumoniae

Abstract

Abstract:Objective: The efflux pump (EP) is one of the major mechanisms of antibiotic resistance in Klebsiella pneumoniae. However, there are few reports on the effect of the abuse of antibiotic use on the activity of EPs. To determine whether the use of low efficacy antibiotics has any effect on the activity of EPs and induces drug resistance in K. pneumoniae, we investigated the effect of ciprofloxacin on the activity of EPs in K. pneumoniae strains. Methods: Sixteen susceptible K. pneumoniae strains were isolated from patients and their minimum inhibitory concentrations (MICs) of ciprofloxacin were measured in the absence and presence of the pump inhibitor carbonyl cyanide m-chlorophenyl hydrazone (CCCP). The strains were then induced with a gradient of ciprofloxacin until the MICs of the strains showed no further increase, to obtain induced resistant strains. The EP activities of the strains before and after induction were compared using EP inhibition and ethidium bromide (EtBr) accumulation assays. Results: The MIC values of the strains were 16-256 times higher after induction than before induction. In the presence of CCCP, the MIC values of 50% of the induced strains were 2-4-fold lower than that in the absence of this inhibitor. The EtBr accumulation assay showed that the fluorescence of EtBr in the induced cells was lower than that in the cells before induction. Conclusions: EPs are widespread in susceptible and drug-resistant K. pneumoniae strains. Induction with ciprofloxacin may increase the activity of EPs in K. pneumoniae. The EtBr accumulation assay is more sensitive than the EP inhibition assay in evaluating the activity of EPs in K. pneumoniae.

Assessment of antibiotic resistance in Klebsiella pneumoniae exposed to sequential in vitro antibiotic treatments

“…The emergence and spread of antibiotic-resistant bacteria has been a growing concern over the last decade, which can lead to serious clinical and public health problems. Klebsiella pneumoniae , an opportunistic pathogen, is mainly responsible for nosocomial infections with high morbidity and mortality [2]. Recently, the rapid emergence of extended-spectrum β-lactamase (ESBL) producing K .…”

“…Furthermore, multidrug-resistant K . pneumoniae strains can cause treatment failure with current antibiotic therapy [2]. …”

“…pneumoniae against different classes of antibiotics include release of antibiotic-inactivating enzymes, modification of antibiotic target sites, change in membrane permeability, activation of efflux pump systems, and alteration of metabolic pathways [2, 5]. Among these mechanisms, the enzymatic degradation and efflux pump systems play an important role in the development of multidrug resistance in K .…”

“…pneumoniae strains produce enzymes, including extended-spectrum β-lactamases, metallo-β-lactamases, oxacillinases, and carbapenemases, that can degrade β-lactam antibiotics. The efflux pumps, belonging to the resistance-nodulation-division (RND) family, can extrude amphiphilic and charged antibiotics such as β-lactams, fluoroquinolones, and aminoglycosides [2]. …”

Characteristics of Klebsiella pneumoniae exposed to serial antibiotic treatments

“…extended-spectrum β-lactamases, metallo-β-lactamases, oxacillinases, carbapenemases을 생성하고, resistance-nodulationdivision (RND) family에 의해 기질인 β-lactam, fluoroquinolone, aminoglycoside를 세포 밖으로 배출한다 (Rice et al, 1991;Zhong et al, 2013). K. pneumoniae를 포함한 많은 다제내성균 의 출현과 확산을 감소시키기 위해서는 적절한 항생제의 처방 이 요구된다 (Warren et al, 2004).…”