Abstract
Study of Cross-resistance to other antimicrobial agents and efflux pump (EP) resistance mechanism in Benzalkonium Chloride (BC) adapted Pseudomonas aeruginosa isolates. Minimum inhibitory concentration of BC of 88 P. aeruginosa isolates that collected from clinical settings in Egypt and Cross-resistance of BC-adapted isolates to other antimicrobial agents were determined by agar dilution method. EP regulatory genes (i.e. MexR, NfxB, MexT, and MexZ) were detected by PCR in BC adapted isolates, and then EP activity of isolates which have these four genes was determined by cartwheel method followed by sequencing for the isolate which showed the highest EP activity. Finally; the expression of EP genes (MexA, MexC, MexE, and MexX) was determined in the same isolate by real-time polymerase chain reaction (RT-PCR) in presence and absence of the most potent efflux pump inhibitor (EPI). Twenty isolates were BC-adapted with MIC 2048 mg/L, showed Cross-resistance to Cetrimide and Ciprofloxacin but not to other disinfectants used. The isolate no. 87 selected to be sequenced. Mutation founded in MexR (V126E) and MexZ (L138R) genes. By RT-PCR, Sertraline (the most potent EPI used) decreased the expression of the EP genes to three-folds. These results demonstrate that efflux-pump was the major mechanism of resistance to BC.
Highlights
Disinfectants have a vital role in keeping acceptable health standards by significantly decreasing microbial loads and inactivating pathogens (Antonio et al, 2017)
Minimum inhibitory concentration (MIC) of Benzalkonium chloride (BC) of 88 P. aeruginosa isolates that collected from clinical settings in Egypt and cross-resistance of BC-adapted isolates to other antimicrobial agents were determined by agar dilution method
By realtime polymerase chain reaction (RT-PCR), sertraline decreased the expression of the efflux pump (EP) genes to three-folds. These results demonstrate that EP was the major mechanism of resistance to BC
Summary
Disinfectants have a vital role in keeping acceptable health standards by significantly decreasing microbial loads and inactivating pathogens (Antonio et al, 2017). Benzalkonium chloride (BC) is the most important QACs used for surfaces disinfection in medical care applications because of their antibacterial activity (Antunes et al, 2016) in addition to its important use as a preservative in aqueous formulations to prevent several infections (Nones et al, 2017). Pseudomonas aeruginosa resists the lethal effects of BC by several mechanisms, such as increased efflux pump activity, mutations in GyrA and ParC genes that encode DNA gyrase and topoisomerase IV in addition to changes in the bacterial membrane (Ferreira et al, 2011). While there are at least 12 structural genes for the resistance-nodulation-division efflux systems have been identified in P. aeruginosa genome, four of them are clinically-important (MexAB-OprM, MexCD-OprJ, MexEF-OprN, and MexXY-OprM) (Lister et al, 2009). Mex systems co-expression has been reported in P. aeruginosa clinical isolates where its variable effect on antibiotic susceptibility has been observed (Poonsuk and Chuanchuen, 2014)
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