Evaluation and Molecular Characterization of Colistin-Resistant Isolates of <i>Pseudomonas aeruginosa</i> and <i>Klebsiella pneumoniae</i> from the Infected Wounds of Hospitalized Patients

This study was planned to determine the colistin-resistant (CR) gene distribution among two species of gram-negative bacteria, <i>Pseudomonas aeruginosa</i> and <i>Klebsiella pneumoniae</i>. In total, 50 isolates of <i>K. pneumoniae</i> (14 isolates, 28%) and <i>P. aeruginosa</i> (36 isolates, 72%) were isolated between August 2023 and October 2023 from clinical wound samples at Jinnah Hospital and Lahore General Hospital Lahore, Pakistan. To determine the resistance genes linked to CR and assess antimicrobial susceptibility, all isolates were kept at -80°C in 15% glycerol broth. Using the right primer sets, a polymerase chain reaction (PCR) was utilized to identify the CR-associated <i>mcr-1</i> gene of the gram-negative isolates. Out of 50, 40 isolates (80%) showed resistance against colistin with MICs of 8 and 128 μg/ml. The majority (97%) of <i>P. aeruginosa</i> CR strains were considered multidrug resistant (MDR). All <i>K. pneumoniae</i> isolates were resistant to cefepime, cotrimoxazole, ceftriaxone, and imipenem. The clinical CR isolates of <i>P. aeruginosa</i> were highly resistant to ceftriaxone, imipenem, cefepime, cotrimoxazole, ciprofloxacin, amikacin, and piperacillin/tazobactum. The antibiotic resistance pattern was terrifyingly high among both bacterial species. According to the PCR results, CR was prevalent among the gram-negative samples, and the <i>mcr-1</i> gene was positive in 6/40 (15%) of the CR isolates, including four <i>P. aeruginosa</i> and two <i>K. pneumoniae</i> strains. The high CR (80%) reported in this research is cause for concern and underscores an urgent need to use colistin in a limited and logical manner, similar to other antibiotics.