Comparison of Molecular Method and Culture in Detection of Community Acquired Pneumonia in Under Five Year Children in Assam, India

Abstract

Introduction: Pneumonia is the single largest infectious cause of death in children worldwide. Aetiology of pneumonia can be identified using multiple diagnostic tools including culture, serology and Polymerase Chain Reaction (PCR); common pathogens include Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, some atypical bacteria like Mycoplasma pneumoniae and Chlamydophila pneumoniae. Aim: To find out the bacteriological agents causing Community Acquired Pneumonia (CAP) in under five year children and to compare the conventional culture and PCR in identifying the pathogen. Materials and Methods: This cross-sectional study was undertaken in the Department of Microbiology and Department of Paediatrics in a tertiary care centre of Assam, India, between March 2016 to September 2018. The study was undertaken with 200 under five year old children who were clinically diagnosed as CAP. Oropharyngeal (OP) swabs and blood culture were processed for bacteriological culture. PCR assay of OP swabs for Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus etc., including atypical bacteria like Mycoplasma pneumoniae and Chlamydophila pneumoniae were performed. Data entry, database management and statistical analysis were performed using Epi-Info software version 7.0. Results: A total of 200 subjects were included in the present study with a male:female ratio of 1.63:1. Most of the study subjects were <11 months of age. Most common isolates were Streptococcus pneumoniae (26.5%) and Staphylococcus aureus (25%) from OP swabs; blood culture revealed mostly Staphylococcus aureus (59%) and Streptococcus pneumoniae (25%). PCR assay of OP swabs were found positive mostly for Staphylococcus aureus (47%), Streptococcus pneumoniae (21.5%) while two children were positive for Haemophilus influenzae; Bordetella pertussis was detected in one child. On evaluation, PCR assay in detecting the bacterial pathogen was found statistically more significant than conventional culture of OP swabs (p<0.05). Conclusion:Staphylococcus aureus and Streptococcus pneumoniae were the most common bacterial organisms in the study. PCR assay was found to be more useful in diagnosing the pathogen for bacterial pneumonia including those difficult to grow in conventional culture.

Keywords

• atypical bacteria
• bacteriological culture
• polymerase chain reaction
• selective medium