Differences and trends in pathogens between ventilator-associated pneumonia and non-ventilator-associated pneumonia: data from 61 hospitals in Suzhou, China, 2020-2024.

Abstract

To investigate the differences in pathogenic bacterial profiles between ventilator-associated pneumonia (VAP) and non-ventilator-associated hospital-acquired pneumonia (NV-HAP) and to provide data to support clinical infection prevention and control. A retrospective observational study using surveillance data, accompanied by a statistical analysis of pathogen-related variables between the two study cohorts. Sixty-one secondary and tertiary healthcare institutions in a single city. Data were extracted from the city's regional healthcare-associated infection surveillance platforms. Inpatients (≥18 years old) diagnosed with confirmed hospital-acquired pneumonia (HAP), including VAP and NV-HAP, at the aforementioned 61 healthcare institutions during the study period. Patients with community-acquired pneumonia (CAP) were excluded. (1) Pathogen distribution in patients with VAP and NV-HAP; (2) temporal trends in pathogen isolation rates (January 2020-December 2024) in both groups; (3) antimicrobial resistancecharacteristics of major pathogens, including detection/composition ratios of key multidrug-resistant organisms (MDROs): carbapenem-resistant <i>Acinetobacter baumannii</i> (CRAB), methicillin-resistant <i>Staphylococcus aureus</i> (MRSA), carbapenem-resistant <i>Escherichia coli</i> (CREC), carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP) and carbapenem-resistant <i>Pseudomonas aeruginosa</i> (CRPA); (4) susceptibility of major pathogens to antimicrobials. Pathogen distribution differed between the two groups, with Gram-negative bacteria being predominant in both groups (73.72% vs 80.98%). Among patients with NV-HAP, the isolation rates of <i>K. pneumoniae</i>, <i>Burkholderia cepacia</i> and <i>Candida albicans</i> showed a decreasing trend, whereas <i>A. baumannii</i> exhibited a slow increase. In patients with VAP, the isolation rates of <i>K. pneumoniae</i> and <i>B. cepacia</i> decreased, whereas <i>Stenotrophomonas maltophilia</i> increased. The proportion of drug-resistant bacteria was higher in patients with VAP than in those with NV-HAP (28.12% vs 19.74%). CRAB showed higher detection and composition ratios in the former group (77.37% and 48.05%, respectively). The MRSA detection rates were approximately 50% in both groups, whereas the CREC detection rate was below 6%. CRPA detection increased in patients with VAP, whereas CRKP and CRPA detection rates decreased in patients with NV-HAP. The antimicrobial resistance profiles of major pathogens were similar between the two groups. <i>K. pneumoniae</i> and <i>E. coli</i> remained susceptible to most antimicrobials, whereas CRKP and CREC were susceptible to only a few agents, such as tigecycline and polymyxin B. <i>A. baumannii</i> exhibited high resistance rates, with both <i>A. baumannii</i> and CRAB being susceptible only to tigecycline, minocycline and polymyxin B. <i>P. aeruginosa</i> and CRPA were largely susceptible to most antimicrobials. <i>S. maltophilia</i> exhibited a ceftazidime resistance rate exceeding 36%, and <i>B. cepacia</i> exhibited ticarcillin/clavulanate and cefoperazone/sulbactam resistance rates exceeding 67%. The resistance rates of <i>S. aureus</i> and MRSA to penicillin, erythromycin and clindamycin ranged from 41.83% to 98.72%. The resistance rates of <i>C. albicans</i> to commonly used antifungal agents were below 8%. The two groups differed in the distribution and antimicrobial resistance of the pathogens and MDROs, and these profiles fluctuated over time. Patients with VAP have a higher percentage of drug-resistant bacteria, requiring special attention to CRAB and CRPA. Local microbiological epidemiological surveillance should be strengthened to improve infection prevention, control strategies and guide empirical antibiotic therapy.