A Study on Analysis of the Sputum Gram Staining and Culture in Patients with Lower Respiratory Tract Infections Attending a Tertiary Care Hospital

• Author Details:   
• Nithya Chinnnusamy
• Vijayalaksmi Arumugam
• Dillirani Vedachalam

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Background: Microscopical examination of expectorated sputum samples is the most commonly followed method in the Microbiological laboratory for diagnosis of lower respiratory tract infections (LRTIs). Sputum sample is usually contaminated with normal resident floral organisms of the oropharynx. For the diagnosis and management of LRTIs, collection of sputum sample, sputum microscopy and culture is very important. The present study was conducted to analyse the importance of the microscopical examination of Gram stained sputum smears and the sputum culture in patients with LRTIs.
Materials & Methods: The place of the study was in the department of Microbiology in a tertiary care hospital. The study period was for one year from Jan 2015 to Dec 2015. Gram staining and culture were done for all the 130 sputum samples. Gram stained sputum smears were observed under microscope for presence of organisms, pus cells and epithelial cells. Quality of expectorated sputum samples were assessed by using Bartlett’s grading system. By using standard protocols bacterial isolates were identified. Kirby Bauer disc diffusion method on Mueller Hinton agar was performed for antibiotic susceptibility testing.
Results and conclusion: Out of 130 sputum samples, 72 (55.4%) samples were acceptable based on Bartlett’s screening system and 58(44.6%) samples were in the not acceptable category. Among acceptable category, 64(78.05%) samples were showed culture positivity. Among non-acceptable category, 18(21.95%) samples were showed culture positivity. Klebsiella pnemoniae-31.71% was the commonest isolated organism followed by  Pseudomonas aeruginosa-14.63% and Staphylococcus aureus -13.41%.In this study authors recommended to  receive good quality of sputum and do  initial  sputum screening  for diagnosing clinically relevant LRTIs.

Keywords: Bartlett’s grading system, Gram stain, Non-acceptable category, Sputum acceptable category, Sputum culture