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Updated: May 6, 2026
Murine Oropharyngeal Aspiration Model of Ventilator-associated and Hospital-acquired Bacterial Pneumonia
Published on: June 28, 2018
Aetiological agents of ventilator-associated pneumonia and its resistance pattern - a threat for treatment
Mv Pravin Charles1, Joshy M Easow, Noyal M Joseph
1Departments of Microbiology, Mahatma Gandhi Medical College and Research Institute, Pondicherry, India.
Background:
Ventilator-associated pneumonia (VAP) is a common type of nosocomial pneumonia encountered in intensive care units. There are several aetiological agents which make treatment challenging. Improper antibiotic treatment of ventilated patients may lead to the emergence of multidrug resistant (MDR) pathogens.
Method:
A prospective study was performed over a period of 20 months. Our study had two arms: the first, 'Incidence and risk factors of VAP in a tertiary care hospital' was the subject of an earlier publication; we therefore present the second investigative arm in this work. The aetiological agents of patients on mechanical ventilation (MV) were identified by standard bacteriological method. The susceptibility pattern was evaluated by Kirby-Bauer disc diffusion method. Extended spectrum beta lactamase (ESBL) testing was performed by combination disc method, and metallo-beta lactamase (MBL) testing was performed by EDTA disk synergy test (EDS).
Results:
Late-onset VAP was associated with Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli, while early-onset VAP was commonly caused by members of Enterobacteriaceae, Candida albicans and Staphylococcus aureus. 72.2 per cent of VAP patients had monomicrobial and 27.8 per cent had polymicrobial infection. Out of the 24 isolates obtained from patients with VAP, seven (29.2 per cent) were MDR pathogens. ESBL and MBL production was detected in 40 per cent and 20 per cent of Klebsiella pneumoniae isolated in our study. Around 50 per cent of isolates associated with late-onset VAP were MDR, while 22.2 per cent isolates obtained from patients with earlyonset VAP were MDR.
Conclusion:
VAP is a nosocomial pneumonia that is common among ventilated patients. The aetiological agents vary from common organisms to MDR pathogens that are difficult to treat. A proper knowledge of MDR pathogens and early isolation followed by prevention of prolonged antibiotic therapy can reduce the mortality of late onset VAP.
Insights
Ventilator-associated pneumonia (VAP) is a common ICU infection caused by diverse pathogens, including multidrug-resistant (MDR) organisms. Early identification and targeted antibiotic strategies are crucial for managing MDR VAP and reducing patient mortality.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Critical Care Medicine
Background:
- Ventilator-associated pneumonia (VAP) is a significant nosocomial infection in intensive care units.
- Diverse etiological agents complicate VAP treatment, with improper antibiotic use potentially driving multidrug-resistant (MDR) pathogen emergence.
Purpose of the Study:
- To investigate the etiological agents causing VAP in a tertiary care hospital.
- To determine the prevalence of multidrug-resistant (MDR) pathogens in VAP cases.
- To analyze the susceptibility patterns and resistance mechanisms (ESBL, MBL) of VAP pathogens.
Main Methods:
- Prospective study over 20 months, focusing on the etiological agents of VAP.
- Bacteriological identification of causative agents from mechanically ventilated patients.
- Antimicrobial susceptibility testing using Kirby-Bauer disc diffusion, with specific assays for ESBL and MBL production.
Main Results:
- Late-onset VAP was linked to Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli; early-onset VAP involved Enterobacteriaceae, Candida albicans, and Staphylococcus aureus.
- Monomicrobial infections occurred in 72.2% of VAP patients, polymicrobial in 27.8%.
- 29.2% of VAP isolates were MDR pathogens; 40% of Klebsiella pneumoniae isolates produced ESBL, and 20% produced MBL. MDR prevalence was higher in late-onset VAP (50%) compared to early-onset (22.2%).
Conclusions:
- VAP is frequently caused by a range of pathogens, including challenging MDR strains.
- Understanding the specific MDR pathogens and their resistance mechanisms is vital for effective VAP management.
- Early isolation of pathogens and judicious antibiotic use, avoiding prolonged therapy, can decrease mortality in late-onset VAP.
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