Screening of campylobacter by Gram staining and culture confirmation in diarrheal stool: a qualitative study

Campylobacter is an important cause of diarrhoeal illness in children. As isolation of these fastidious bacteria from stool samples is laborious and expensive, it is not routinely investigated in certain geographical areas. This study aimed to demonstrate the utility of Gram staining as a rapid and cost-effective screening method for the detection of Campylobacter in stool specimens from children with acute diarrhoea.

Stool samples from 138 children below 12 years of age at a tertiary care centre were screened by Gram staining for Gram-negative spiral bacilli. Smear-positive samples were subjected to culture on campylobacter selective medium. Isolates were confirmed by polymerase chain reaction (PCR) targeting the genus-specific 16S rRNA gene and the mapA and ceuE genes, to Campylobacter jejuni and C.coli respectively. Antibiotic susceptibility testing was performed by the Kirby-Bauer disc diffusion method against erythromycin and ciprofloxacin.

Gram-negative spiral bacilli were detected in 15 (10.86%) and 13 were confirmed by culture (positive predictive value of Gram staining: 86.66%). One sample was positive on direct PCR with no growth. Of the isolates, 11 were identified as C. jejuni, one C.coli, and one as non-jejuni/non-coli. All isolates were susceptible to the tested antibiotics.

Gram staining of stool is rapid, low-cost and practical screening method for campylobacteriosis. With positive predictive value of 86.66%, it offers a valuable first-line diagnostic tool. C.jejuni is the predominant species in this paediatric population and the absence of antibiotic resistance supports the continued use of erythromycin and ciprofloxacin as first-line therapeutic agents.