Background: Ventilator-Associated Pneumonia (VAP) is the most frequent intensive-care-unit (ICU)-acquired infection. The aetiology of VAP varies with different patient populations and types of ICUs. Methodology: A prospective study was performed over a period of 15 months in a tertiary care hospital to determine the various aetiological agents causing VAP and the prevalence of multidrug resistant (MDR) pathogens. Combination disk method, Modified Hodge test, EDTA disk synergy (EDS) test and AmpC disk test were performed for the detection of extended spectrum beta-lactamases (ESBL), carbapenemases, metallo-beta-lactamases (MBL) and AmpC β-lactamases respectively. Results: Enterobacteriaceae, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, Candida spp. were more common in early-onset VAP, while non-fermenters (Pseudomonas spp. and Acinetobacter spp.) were significantly associated with late-onset VAP (P value 0.0267, Chi-square value 4.91). Thirty-seven (78.7%) of the 47 VAP pathogens were multidrug resistant. ESBL was produced by 50% and 67% of Escherichia coli and Klebsiella pneumoniae respectively. MBL was produced by 20% of P. aeruginosa. AmpC beta-lactamases were produced by 33.3% and 60.7% of the Enterobacteriaceae and non-fermenters respectively. Of the S. aureus isolates, 43% were methicillin resistant. Prior antibiotic therapy and hospitalization of five days or more were independent risk factors for VAP by MDR pathogens. Conclusions: VAP is increasingly associated with MDR pathogens. Production of ESBL, AmpC beta-lactamases and metallo beta-lactamases were responsible for the multi-drug resistance of these pathogens. Increasing prevalence of MDR pathogens in patients with late-onset VAP indicate that appropriate broad-spectrum antibiotics should be used to treat them.

Background: Pseudomonas aeruginosa and Acinetobacter baumannii have been reported to cause outbreaks of ventilator-associated pneumonia (VAP) in several studies. The high prevalence of these pathogens prompted us to study the different strains of these pathogens prevailing in our intensive care units (ICUs) and determine the role of ICU environment and health-care workers (HCWs) in the transmission of infection. Methodology: A prospective study was performed over a period of 15 months in two ICUs of Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry, India. Surveillance samples were collected from the HCWs and the ICU environment. Quantitative antibiogram typing and PCR-RFLP were used for comparison of the isolates from the surveillance samples and VAP patients. Results: Pseudomonas aeruginosa and Acinetobacter baumannii were the most common potential VAP pathogens isolated from the surveillance cultures. Eight strains of Pseudomonas aeruginosa were present in our ICUs, but multi-drug resistant (MDR) strain 2 and strain 4 were the most prevalent strains. Six strains of Acinetobacter baumannii were found in our ICUs, of which MDR strain 1 and strain 3 were the most common. The strains of Pseudomonas aeruginosa and Acinetobacter baumannii observed in the VAP patients were also found in the ICU milieu. Only one HCW was found to be the carrier of a Pseudomonas aeruginosa strain present in a VAP patient. Conclusions: The ICU environment was observed to be the potential reservoir for VAP pathogens; therefore, strict adherence to environmental infection control measures is essential to prevent health-care-associated infections.

The KBDD method can be reliably used for routine testing of meropenem resistance in A. baumannii, A. lwoffii and P. aeruginosa. However, further studies are needed before employing this technique for detecting meropenem resistance in Pseudomonas spp.

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