Significance of Gram’s stain in the diagnosis and management of Lower respiratory tract infections

Abstract

Objective: To establish the importance and relationship of Gram’s staining and positivity of sputum culture in lower respiratory tract infections

Study Design: Experimental study.

Place and Duration of Study: This study was carried out in the Dept. of Microbiology Basic Medical Sciences Institute, Jinnah Postgraduate Medical Center, from January 2001 to September 2001.

Materials and Methods: Sputum sample of   one hundred clinically suspected cases of lower respiratory tract infections attending OPD or admitted in the wards were included in the study. Early morning   sputum samples were collected in sterile container. Gram’s staining culture and sensitivity were carried out according to the standard methods.

Results: It was very interesting to note that a direct relationship exists between Gram’s staining and positivity of culture. Number of pus cells seen per HPF was directly proportional to the isolated bacterial pathogen. <15 pus cells /HPF had 13.2% cases positive for bacterial pathogen. Pus cells15- 20/HPF had 54.5% cases positive for bacterial pathogen and specimens in which there were >20 pus cells/HPF, 90% cases were positive for bacterial pathogen. 

Conclusion: Gram’s staining is a simple and cost effective method that could provide a basis for culture positivity of the specimen. Higher the number of pus cells in sputum sample greater was the culture positivity. Based on Grams staining results it would be possible to start empiric therapy and alter the therapy after the sensitivity of isolates if needed.