Ventilator associated pneumonia: bacterial isolates and its antibiotic resistance pattern

Keywords: Amp C ß lactamase Extended spectrum ß lactamase Metallobetalactamase Multidrug resistant organisms Ventilator associated pneumonia. Aims: Ventilator Associated Pneumonia (VAP) is the most frequent intensive care unit (ICU) acquired infection. Due to the increasing incidence of multidrug resistant organisms (MDR) in the ICU, early and correct diagnosis of VAP is an urgent challenge for optimal antibiotic treatment. The aim of the study was to detect the bacterial pathogens and to know their susceptibility pattern among clinically suspected VAP cases. Materials and Methods: Patients admitted to ICU fulfilling the clinical criteria for VAP were included in the study. Endotracheal aspirate (EA) was collected aseptically and processed. Gram stain smear showing > 25 pus 5 cells/ low power field were cultured and growth of > 10 cfu were considered as pathogens. The isolates were subjected to antibiotic sensitivity testing by Kirby Bauer disc diffusion method. Isolates resistant to 3rd generation cephalosporins were screened for the production of ESBL and AmpC ß lactamase. Isolates resistant to carbapenems and cefoxitin were screened for MBL and MRSA respectively. Results: A total of 806 patients were put on mechanical ventilation in different health care centres during Jan 2006-Dec 2010. At 48 hrs, 328 patients were weaned from ventilator support. The rate of VAP was 21%. The infection was polymicrobial in 20.29% cases. Gram negative bacilli were isolated in 351 cases (73.43%). Acinetobacter baumannii (22.17%) was the major pathogen isolated, followed by Pseudomonas aerugionsa (19.66%). Among the gram positive cocci isolated Staphylococcus aureus (11.44%) was predominant. Klebsiella pneumoniae (32.18%) and Escherichia coli (66.66%) were ESBL producers. Pseudomonas aeruginosa (2.19%) and Acinetobacter baumannii (0.9%) were Amp C ß lactamase producers. Conclusion: Rate of VAP in ICUs was high. MDR gram negative bacilli were the major pathogens. Judicious and timely use of appropriate antibiotic can reduce morbidity, mortality and high cost incurred because of longer ICU stay due to VAP.