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Indian Journal of Microbiology Research


To define usefulness of blood culture in microbiological diagnosis of ventilator- associated pneumonia (VAP)


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Author Details: Kotgire Santosh A

Volume : 3

Issue : 2

Online ISSN : 2394-5478

Print ISSN : 2394-546X

Article First Page : 118

Article End Page : 121


Abstract

Background and Objectives: The rate of positive blood culture in ventilator- associated pneumonia (VAP) ranges from 8-20% and some studies report that bacteremia is not always related to pulmonary infection. The present study was undertaken to assess the usefulness of blood culture in microbiological diagnosis of VAP.
Material and Methods: The study was carried out in the Department of Microbiology, Dr. Ulhas Patil Medical College for a period (January 2013 to December 2014). 85 patients receiving mechanical ventilation hospitalized for more than 48 hrs, were evaluated for VAP.
Endotracheal aspirate (ETA) and blood culture performed after establishing a clinical diagnosis of VAP using mucus extractor and 2 set of blood culture bottles (Himedia Mumbai) was used respectively. A growth of organism more than 105 cfu/ml was considered as microbiological VAP while less than 105 cfu/ml was considered as not significant or commensal growth. Bacteremia was diagnosed when both 2 set of blood culture yields a microorganism or when only one set was positive but same microorganism was present in ETA in concentration more than 105 cfu/ml.
Result: 39(45%) patients were ETA positive and remaining 46(55%) does not yield any significant growth of microorganisms while in blood culture only 12(14.11%) shows same isolate that were found in ETA culture while in 10(11.76%) blood culture microorganism were found which were not the same microorganism isolated from ETA culture and were considered as extra pulmonary source.
Conclusion: Blood culture have limited value in microbiological diagnosis of VAP. ETA shows 45% positive culture while blood culture yields only 25.88% positive culture. Blood culture may be useful in finding extrapulmonary source of infection associated with VAP.

Key Words:
Blood Culture, Ventilator Associated Pneumonia, Bacteremia