Role of Multidrug-resistant Pathogens in Ventilator-Associated Pneumonia in a Tertiary Care Hospital in India

Ventilator-associated pneumonia (VAP) is the second most common infection acquired in the intensive care unit (ICU). Bacteriological profiles cause VAP and their susceptibility patterns vary in different institutions.

A prospective study was conducted from June 2017 to May 2018 in a tertiary care hospital as per the recent NHSN guidelines in finding the incidence of VAP and further determining the etiological agents by both conventional and automated methods. The combination disk method (Phenotypic confirmatory test), ampicillin C (AmpC) disk test, modified carbapenem inactivation method, imipenem/ethylenediamine tetraacetic acid combined disc test, and cefoxitin disk test were performed for the detection of extended-spectrum beta-lactamases (ESBL), AmpC β-lactamases, carbapenemases, metallo-beta-lactamases (MBL), and methicillin-resistant Staphylococcus aureus, respectively.

Among 104 patients, 31 cases developed PVAP (possible VAP) during their ICU stay; of these cases, two patients had two episodes of VAP each, and the incidence of VAP was 32%. The most common isolate was Acinetobacter baumannii (38%), followed by Pseudomonas aeruginosa (22%), Klebsiella pneumoniae (16%), and Escherichia coli (13.51%). Twenty (54%) of the 37 VAP pathogens were multidrug resistant. ESBL was produced by 40% and 67% of E. coli and K. pneumoniae, respectively. MBL was produced by 25% of P. aeruginosa. In addition, AmpC beta-lactamases were produced by 18% each of the Enterobacteriaceae and non-fermenters, respectively. One of the two S. aureus isolates was methicillin-resistant.

The majority of VAP cases in our setting were caused by highly resistant strains. The frequency of specific multidrug resistance pathogens causing VAP may vary due to hospital, patient population, exposure to antibiotics, type of ICU patients, and changes over time, emphasizing the need for timely local surveillance data.