The Effect of pH Variation on Antibiotic Susceptibility of MDR <i>Klebsiella pneumoniae</i> Isolates

Background: Klebsiella pneumoniae is a significant opportunistic pathogen responsible for various nosocomial infections in humans. The emergence of multi-drug resistant strains poses a significant challenge in clinical settings, necessitating a deeper understanding of factors influencing antimicrobial resistance. Objective: This research aimed to investigate the impact of pH variation on the resistance patterns of multi-resistant K. pneumoniae isolated from Iraqi patients with urinary tract infections and wound infections against different antibiotics. Methods: Forty K. pneumoniae isolates were obtained from urine samples and wound swabs, and their identification was confirmed using the VITEK ® 2 compact system and molecular identification of the rpoB housekeeping gene. Antibiotic susceptibility testing was performed using the Kirby Bauer’s disk diffusion method under varying pH conditions (pH 5, 7, 9, and 11) at 37°C for 18 to 24 hours. Results: The study findings indicated that K. pneumoniae isolates exhibited differential susceptibility to antibiotics based on pH conditions. Cefotaxime demonstrated increased efficacy under alkaline pH, while tetracycline showed optimal efficacy under acidic conditions. However, ciprofloxacin displayed resistant phenotypes at acidic pH 5 and either resistant or intermediate phenotypes at alkaline pH 9. Conclusions: The results suggest a potential influence of pH on the antibiotic susceptibility profiles of K. pneumoniae isolates. Understanding the role of pH in antimicrobial resistance can inform strategies for better managing infections caused by multi-resistant pathogens. Further research is warranted to elucidate the underlying mechanisms and implications for clinical practice.