A bacterial and fungal profile of sputum samples in a tertiary care hospital in Puducherry

Abstract

The microscopic examination of gram stained sputum sample aids in diagnosis of patients with lower respiratory tract infections. Gram stain plays the key role in deciding the appropriateness of the quality of the sputum sample received in the laboratory for culture. It helps to determine the represent ativeness of the sample for the site of collection intended. Aim: This study was done to correlate gram stain findings with culture and to assess the use of Gram stain in sputum examination in diagnostic microbiology. Materials and Methods: During 2017 (July to December) a total of 133 sputum samples were quality assessed using Bartlett's grading system. The total scoring was done and sample showing score of 1 and above were cultured and identified based on colony characteristics, gram staining morphology and biochemical reactions. Results: One hundred and thirty-three sputum samples were collected from patients with suspected lower respiratory tract infection. Of the 133 samples, 110(79%) were accepted and 23 (21%) were found to be unacceptable by Bartlett criteria. Potential pathogens were grown in 84 samples in the acceptable category. Normal respiratory flora were grown in 26 samples. Out of 84 samples, 63 samples were positive for bacterial growth and 21 showed fungal growth. Out of 63 bacterial growth, 44 were from in-patients and 19 were from out-patients. Among these bacterial isolates, 23 isolates were Pseudomonas aeruginosa followed by 16 isolates were Klebsiella pneumoniae, 10 isolates were E.coli, 6 isolates were Staphylococcus aureus, 2 isolates were Streptococcus species, 3 isolates were Proteus mirabilis and 3 isolates were Serratia marcesens. Conclusions: All the sputum samples should be subjected to gram staining before culture to differentiate true pathogens from contaminating flora on culture.