Real-time multiplex PCR assay reveals the increased prevalence of Campylobacter spp and diarrhoeagenic Escherichia coli in humans from Vellore, South India

Abstract

Introduction. Bacterial dysentery is one of the greatest causes of morbidity and mortality worldwide. Campylobacter spp. and diarrhoeagenic Escherichia coli (DEC) are recognised as the most common causes of bacterial enteritis in developing countries including India. Hypothesis/Gap statement. Rapid and accurate identification of dysentery causing organisms using molecular methods is essential for better disease management, epidemiology and outbreak investigations. Aim. In view of the limited information available on the dysentery causing agents like Campylobacter spp., enterohemorrhagic E. coli (EHEC)/enteropathogenic E. coli (EPEC) and enteroinvasive E. coli (EIEC)/ Shigella in India, this study was undertaken to investigate the presence of these pathogens in human and poultry stool samples by molecular methods. Methodology. In total, 400 human stool samples and 128 poultry samples were studied. Microaerophilic culture along with real-time multiplex PCR with the targets specific to the genus Campylobacter , Campylobacter jejuni , Campylobacter coli , EHEC, EPEC and EIEC/ Shigella was performed. Further species confirmation was done using MALDI-TOF MS. Results. On microaerophilic culture, C. coli was isolated in one human sample and two C. jejuni and one C. fetus in poultry samples. On PCR analysis, among human stool samples, typical EPEC (42%) was predominantly seen followed by Campylobacter spp. (19%) and EIEC/ Shigella (10%). In contrast, Campylobacter spp. (41%) was predominant in poultry samples, followed by typical EPEC (26%) and EIEC/ Shigella (9%). Poly-infections with Campylobacter spp. and DEC were also observed among both sources. Conclusion. The present study documented the increased prevalence of Campylobacter spp. in humans compared with the results of previous studies from India. Typical EPEC was found to be predominant in children less than 5 years of age in this study. The high prevalence of coinfections in the current study indicates that a multiple aetiology of diarrhoea is common in our settings.