Prevalence and Antimicrobial Resistance of Pseudomonas aeruginosa Recovered from Respiratory and Urinary Specimens in a Lebanese Hospital (2020–2025)

Background: Respiratory tract infections (RTIs) and urinary tract infections (UTIs) are among the most common infections in humans. It is estimated that millions of deaths occur each year worldwide due to these infections. Pseudomonas aeruginosa (P. aeruginosa), in particular, represents a public health threat since it has a high ability to acquire resistance to different antibiotic classes. The aim of this study was to determine the prevalence and antimicrobial resistance patterns of P. aeruginosa isolates from patients with RTIs and UTIs in Lebanon. Methods: This retrospective study was performed during 2020–2022 and 2024–2025. Samples were collected from both inpatients and outpatients, where identification and isolation of bacteria were performed along with antibiotic susceptibility testing. Results: The overall prevalence of P. aeruginosa isolates in RTI cases over the study period was 10.9%, and that of UTI cases was 1.3%. The general antimicrobial resistance profile of P. aeruginosa isolates from RTI and UTI cases showed the highest resistance for Piperacillin–Tazobactam and Aztreonam, respectively. For RTIs, antibiotic resistance decreased from 48.1% in 2020 to 36.7% in 2025 and increased from 16.7% to 19.4% for UTIs. Conclusions: According to our research, P. aeruginosa with low antibiotic susceptibility is frequently found in isolated samples, highlighting the significant challenge in treating severe infectious illnesses. To choose focused and efficient antibiotic therapy for RTIs and UTIs and to stop the emergence of multidrug-resistant (MDR) bacteria, it is essential to accurately identify the pathogenic microorganisms and their antibiotic susceptibility patterns.