Prevalence, microbiological profiles, and determinants of hospital-acquired pneumonia in Addis Ababa: A focus on Pseudomonas aeruginosa and its antimicrobial resistance patterns in three hospitals

Hospital-acquired pneumonia is typically polymicrobial; nevertheless, Pseudomonas aeruginosa is a principal causative pathogen, attributable to its link with poor clinical prognoses and extensive antimicrobial resistance. Our study aims to assess the prevalence, microbiological profiles and determinants of hospital-acquired pneumonia with a focus on antibiotic-resistant P. aeruginosa across three hospitals in Addis Ababa. A cross-sectional study was conducted in which 1,800 patients were screened, and 298 cases of hospital-acquired pneumonia were identified between September 2022 and April 2024. Patient interviews and microbiological analysis of lower respiratory tract samples were performed. We detected a 17% prevalence of hospital-acquired pneumonia and 19% prevalence of ventilator-associated pneumonia across the study hospitals. Our patient profiles indicated a predominance of males (59%), with the largest proportion aged 30-39 years (28%), most were married (71%) and had attained secondary-level education (33%). Over half of the patients were admitted to the adult ICU (55%), 60% had a history of prior hospitalization and respiratory disease was the leading cause of admission (30%). Acinetobacter baumannii (n = 24) was the most frequently isolated pathogen, followed by Pseudomonas aeruginosa (n = 21) and Staphylococcus aureus (n = 13). Compounding these challenges, the P. aeruginosa isolates (7%) exhibited high resistance to ceftazidime and cefepime (89% resistance), while retaining relatively high susceptibility to amikacin (90%); notably, 67% of the isolates were multidrug resistant. We tested several patient-level vulnerabilities, only aspiration remained independently associated with presence of pneumonia-associated pathogen in patient samples (AOR = 4.43, 95% CI: 1.74-11.24, p = 0.002). This study demonstrates a substantial burden of multidrug resistance hospital-acquired pneumonia by ESKAPE pathogens that indicate deficiencies in hospital defences against hospital-acquired pathogens and risk of adverse patient outcomes. There is an urgent need to shift infection prevention strategies, emphasizing aspiration prevention measures and strengthened diagnostic stewardship.