Exploring novel amides as efflux pump inhibitors for overcoming antibiotic resistance in multidrug-resistant Pseudomonas aeruginosa.

Background and objectives: Pseudomonas aeruginosa (P. aeruginosa), a multidrug-resistant bacterium, represents a considerable risk in healthcare environments owing to its capacity to induce various infections. The resistance of P. aeruginosa is frequently linked to efflux pumps that actively remove antibiotics from the bacterial cell. This study investigates novel amide compounds as potential alternatives to address P. aeruginosa isolates exhibiting multidrug resistance mediated by efflux pumps.

Materials and methods: Gram staining and biochemical assays revealed thirty-three multi-drug-resistant P. aeruginosa isolates from a tertiary care hospital Peshawar. After antibiotic susceptibility testing, efflux pumps were detected using Ethidium Bromide (EtBr) agar cartwheel technique and UV transilluminator. Novel amides were tested for efflux pump and anti-pseudomonal action against efflux pump-positive isolates utilizing agar well diffusion and micro broth dilution, including synergy with ciprofloxacin and gentamicin.

Results: Three high efflux pump activity P. aeruginosa isolates were chosen using ETBr agar cartwheel technique. Novel amides (ITC, ITD, ITE, DEP) block efflux pump, although TEM-cu is very antimicrobial. TEM-cu, DEP, ITC, and ITE have 0.19, 0.78, and 0.78 mg/ml MICs. Effectiveness against efflux pump-expressing P. aeruginosa is lowest with ITE (1.56 mg/ml). Together with ciprofloxacin and gentamicin, TEM-cu and DEP improved antimicrobial effectiveness.

Conclusion: TEM-cu is highly effective against efflux pump-positive P. aeruginosa, while amides like ITC, ITD, ITE, and DEP block these pumps. With significant reductions, DEP and TEM-cu improve ciprofloxacin and gentamicin efficacy. This method may help overcome P. aeruginosa efflux pump-mediated resistance.