Study reveals Antimicrobial resistance in aerobic bacteria isolated from endotracheal aspirate in ventilator-associated pneumonia

Nosocomial pneumonia, the second most prevalent hospital-related infection, is associated with significant morbidity and mortality, making it the most severe type of nosocomial infection. Ventilator-associated pneumonia (VAP) refers to pneumonia developing in a patient using a mechanical ventilator for more than 48 hours after intubation or tracheostomy. Recent study examined trends in demographic details, comorbid conditions, bacterial etiological agents, and their antibiotic resistance patterns causing ventilator-associated pneumonia (VAP) in adults over a 10-year period from 2008 to 2018 at a tertiary care hospital.

Bacterial Etiological Agents and Antibiotic Resistance Patterns

A total of 338 patients diagnosed with VAP were included in the analysis across the three time points of 2008, 2013, and 2018. Over two-thirds of the VAP patients were male, and nearly 45% were in the geriatric age group over 60 years old. The most common comorbid conditions were chronic obstructive pulmonary disease (24.6%), hypertension (19.5%), and diabetes mellitus (16.9%).

Among the bacterial isolates, gram-negative pathogens accounted for 94.9% of cases, with Klebsiella pneumoniae (34.5%), Acinetobacter species (27.0%), and Pseudomonas aeruginosa (16.6%) being the most common. The incidence of Acinetobacter species increased from 18.1% in 2008 to 36.3% in 2018, while Pseudomonas aeruginosa decreased over the study period. Methicillin-resistant Staphylococcus aureus (MRSA) comprised 50% of S. aureus isolates.

Analysis of antimicrobial resistance (AMR) patterns showed high levels of resistance among gram-negative isolates to ampicillin, third-generation cephalosporins (>75%), and gentamicin, levofloxacin, piperacillin/tazobactam (50-75%). Carbapenem resistance increased dramatically, from 20% in 2008 to 82.2% in 2018 for Acinetobacter species. Pseudomonas aeruginosa, Escherichia coli, and Citrobacter species also exhibited significant increases in carbapenem resistance over the decade.

Implications of the Study

The study highlights the growing burden of VAP, particularly driven by multidrug-resistant gram-negative pathogens like Acinetobacter species. The emergence of high-level resistance to key antimicrobial agents like carbapenems is a major concern for clinicians managing VAP in the intensive care setting. Continued surveillance of the evolving microbial epidemiology and antibiotic susceptibility patterns is crucial to guide appropriate empiric antimicrobial therapy and infection control measures in the ICU.

Key Points

Here are the 3 key points from the research paper:

1. The study examined trends in demographic details, comorbid conditions, bacterial etiological agents, and their antibiotic resistance patterns causing ventilator-associated pneumonia (VAP) in adults over a 10-year period from 2008 to 2018 at a tertiary care hospital.

2. The most common bacterial pathogens causing VAP were gram-negative organisms, with Klebsiella pneumoniae, Acinetobacter species, and Pseudomonas aeruginosa being the predominant isolates. The incidence of Acinetobacter species increased significantly over the study period, while Pseudomonas aeruginosa decreased.

3. The study found high levels of antimicrobial resistance among the gram-negative isolates, including to key antimicrobial agents like carbapenems. Carbapenem resistance increased dramatically, particularly for Acinetobacter species, which showed an increase from 20% in 2008 to 82.2% in 2018. This emergence of high-level resistance is a major concern for managing VAP in the intensive care setting.

Reference –

Rao SV, Thilakchand KR, Boloor R, Suresh S, George T, Pais ML, et al. Antimicrobial resistance pattern in aerobic bacteria isolated from endotracheal aspirate in ventilator‑associated pneumonia: Ten years observation from a tertiary care hospital. J Anaesthesiol Clin Pharmacol 2024;40:324‑9.