Antimicrobial resistance patterns of community-acquired pneumonia pathogens: A five-year retrospective study at Hai Phong International Hospital, Vietnam (2020 – 2024)

Abstract

Background: Antimicrobial resistance (AMR) is a growing global crisis and has increasingly complicated the management of community-acquired pneumonia (CAP). In Vietnam, several studies have documented alarming resistance levels among key respiratory pathogens, but multi-year data from tertiary hospitals remain limited. Methods: We conducted a retrospective descriptive study at Hai Phong International Hospital, Vietnam, analyzing 1,418 inpatients with CAP from 2020 to 2024. Eligible patients had received at least one antibiotic, stayed ≥24 hours, and had available clinical, laboratory, and microbiology data. Data were extracted from electronic medical records and the microbiology database. Bacterial isolates were identified, and antimicrobial susceptibility was interpreted according to CLSI/EUCAST standards. Clinical outcomes were assessed based on symptom resolution, biomarker changes (WBC, CRP), and discharge status. Statistical analysis included Chi-square tests, Wilcoxon signed-rank tests, and multinomial logistic regression. Results: The cohort was predominantly elderly (≥60 years, 76.0%) and male (53.1%), with hypertension (53.3%) and diabetes (37.8%) as the most common comorbidities. Positive bacterial cultures were obtained in 22.6% of cases. Pseudomonas aeruginosa (24.9%), Acinetobacter baumannii (19.3%), and Klebsiella pneumoniae (15.3%) were the leading pathogens, while Streptococcus pneumoniae (5.0%) and Haemophilus influenzae (6.9%) were less frequent. Resistance was widespread: E. coli showed 100% resistance to ampicillin and >85% resistance to cefotaxime and ciprofloxacin; Klebsiella spp. exhibited >55% resistance to multiple agents; P. aeruginosa showed >50% resistance to fluoroquinolones and carbapenems; and A. baumannii demonstrated >85% resistance to nearly all tested drugs. Among Gram-positive isolates, S. pneumoniae displayed high resistance to erythromycin (93.3%) and clindamycin (93.8%) but preserved full susceptibility to vancomycin and linezolid. Conclusion: CAP patients at Hai Phong International Hospital demonstrated a predominance of multidrug-resistant Gram-negative pathogens and very high resistance among S. pneumoniae to macrolides. These findings highlight the urgent need for locally tailored empirical therapy, robust antimicrobial stewardship, and continuous surveillance to mitigate the growing AMR burden in Vietnam.