Classification of Bacteroides nodosus by agglutination tests

Area of Science:

• Veterinary Microbiology
• Sheep Pathology
• Bacteriology

Background:

• Ovine footrot, caused by Bacteroides nodosus, is a significant concern in sheep farming.
• Understanding the serological diversity of Bacteroides nodosus is crucial for effective disease control and vaccine development.

Purpose of the Study:

• To serologically classify a large number of Bacteroides nodosus isolates from sheep.
• To investigate the potential for serological subgroups (serotypes) within the identified serogroups.
• To assess the prevalence of mixed serogroup infections in sheep and flocks.

Main Methods:

• Slide agglutination tests were used to classify 1260 Bacteroides nodosus isolates into 8 serogroups (A-H).
• Cross-tube agglutination tests were performed on selected isolates and antisera to explore potential serotypes.
• Multiple isolates from individual sheep and flocks were examined to determine serological diversity.

Main Results:

• 1260 out of 1267 isolates were classified into 8 serogroups (A-H).
• Individual flocks and sheep frequently harbored multiple serogroups, with up to 6 in flocks and 4 in single feet.
• 13% of examined sheep (38 out of 292) had mixed serogroup infections.
• Cross-tube tests indicated the existence of at least 16 serotypes within Bacteroides nodosus.

Conclusions:

• Bacteroides nodosus exhibits significant serological diversity in sheep populations.
• The classification into 8 major serogroups may represent a simplification, with potentially 16 or more serotypes existing.
• Further research is needed to elucidate the specific antigens responsible for agglutination reactions and confirm serotype distinctions.