Background: Respiratory infections in critically ill patients are associated with high morbidity and mortality. Patients who are mechanically ventilated are at high risk of acquiring respiratory tract infections due to a complex interplay between the endotracheal tube, host immunity, and virulence of invading bacteria. To initiate empiric antimicrobial therapy knowledge of local antimicrobial resistance patterns are essential.

Aim: The aim of our study was to identify the bacterial pathogens and their antibiotic susceptibility of endotracheal aspirate samples collected from the patients on mechanical ventilation for more than 48 hours.

Materials and Methods:  This prospective study was done at Saveetha Medical College and Hospital, Chennai. One hundred and seven samples were collected, bacteriological identification and antibiotic susceptibility were tested for pathogen grown in endotracheal cultures received.

Results: Culture was positive in sixty-one out of one hundred and seven samples (i.e., 57% of all the samples) out of which gram-negative bacteria accounted for (59 out of 61) 96.72% cases and rest 2 cases were Candida spp.  Pseudomonas spp 37% (22 out of 61) was the commonest organism isolated followed by Klebsiella spp 33% (20 out of 61), Acinetobacter spp 20% (12 out of 61), Escherichia coli 3.3% (2 out of 61), Enterobacter spp 3.3% (2 out of 61) and Proteus spp 1.6% (1 out of 61). ESBL rate was highest among Acinetobacter spp (100%) followed by Klebsiella spp (40%) and Pseudomonas spp (27%). Most of the Acinetobacter spp 83% (10 out of 12) were Multidrug-resistant whereas five isolates of each of Klebsiella spp (25%) and Pseudomonas spp (23%) were found to be MDR and sensitive to only colistin and tigecycline. Fungal isolates consisted of one case of Candida albicans and Candida non-albicans each.

Conclusion: Gram-negative bacteria especially Pseudomonas spp, Klebsiella spp, Acinetobacter spp are most commonly encountered pathogens isolated in endotracheal samples of ventilator-associated pneumonia patients. Among these pathogens, Acinetobacter spp. shows very high ESBL positivity, while these characteristics are moderately expressed in Klebsiella spp and less commonly in Pseudomonas spp. Multidrug resistance also followed the same trail among these common pathogens.

Keyword: Bronchoalveolar lavage, Endotracheal aspirates, Extended Spectrum Beta-Lactamase (ESBL), Multidrug-resistant.

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Dr Debjita Debnath

Department of Microbiology, Saveetha Medical College & Hospital, Thandalam, Chennai, India

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