Changing trends of antimicrobial resistance in clinical isolates yielded from lower respiratory tract specimens of ICU Patients-A Two-Year Study

Objective: To determine changing trends in antimicrobial resistance among Gram-negative bacterial isolates yielded in lower respiratory tract specimens in intensive care settings. Study Design: Cross-sectional study Place and Duration of Study: Armed Forces Institute of Pathology, Rawalpindi Pakistan, Jul 2018 to Jun 2020. Methodology: The study was carried out on 819 isolates from lower respiratory tract specimens collected from ICUs of multiple centres all over Pakistan. The antimicrobial susceptibility testing was performed according to performance standards provided by CLSI and EUCAST. Antimicrobial resistance trends were analyzed. Results: In Acinetobacter baumannii, resistance increased against Carbapenems (92% to 97.4%) and Polymyxins (0% to 5.3%). Pseudomonas aeruginosa showed increasing resistance, with Imipenem (33.3% to 46.9%), Meropenem (27.3% to 43.6%) and Polymyxin (0% to 3%). In Klebsiella pneumoniae, the resistance against Carbapenems rose from 60.5% to 79.2%, for Imipenem 68.4% to 83% for Meropenem. Polymyxin resistance was much higher in K. pneumoniae (increasing from 22% to 24.5%). In Escherichia coli, resistance increased from 23.5% to 41.7% for Imipenem 35.5% to 50% for Meropenem, and 0% to 8.3% for Polymyxins, whereas Tigecycline showed decreasing resistance trend. Other antimicrobials tested showed increasing resistance as well. Conclusion: Antimicrobial resistance is emerging so rapidly that the post-antibiotic era is approaching sooner than later. Extensive and up-to-date insight regarding antimicrobial resistance rates and trends against significant pathogens is required to deal with this emerging dilemma. (author)