Genotyping of Bacteroides fragilis isolates from stool specimens by arbitrarily-primed-PCR.

The research article investigates the genetic relationship of Bacteroides fragilis isolates gathered from different clinical sources using a technique known as arbitrarily primed Polymerase Chain Reaction (PCR).

Research Methodology

• The researcher used arbitrarily primed polymerase chain reaction (AP-PCR) to determine the genetic relation of Bacteroides fragilis isolates from different sources.
• They used 17 strains isolated from patients with inflammatory bowel disease and 20 strains obtained from foals with diarrhea for their comparison.
• Three reference ATCC strains were also included in the analysis for a more comprehensive evaluation.

Findings

• The study found eighteen different types among the 20 patient isolates when using a 22-mer arbitrary primer (ERIC-2).
• Types 1 (enterotoxigenic) and 9 (nonenterotoxigenic) were detected in the stools of two patients each.
• A high degree of genotypic variability was determined amongst the isolates as most of them exhibited a unique DNA banding pattern.
• For the isolates from the foals, eleven types were identified. Type 20, a nonenterotoxigenic type, was present in 30% of the foals.
• However, no correlation was detected between the isolates from humans and the isolates from horses.

Implication of the Findings

• The study did not find a clear relationship between a disease state – diarrhea or inflammatory bowel disease – and specific Bacteroides fragilis types.
• Aided by AP-PCR, the genetic relatedness could be determined, making it a valuable method for future epidemiologic studies of diarrheal diseases due to B. fragilis.