Virulence factors and biofilm production by isolates of Bacteroides fragilis recovered from dog intestinal tracts

Bacteroides fragilis colonizes dog guts both as a commensal and as an opportunistic pathogen. This study aims to evaluate virulence factors of 13 B. fragilis strains isolated from dog intestinal tracts and their ability for biofilm formation. Capsules were detected in all the evaluated strains. A total of 61.5% of all strains were biofilm producers. These attributes most likely play an important role in B. fragilis persistent colonization in the gut.

Antimicrobial resistance patterns of Bacteroides fragilis group organisms in Korea

Antimicrobial resistance patterns of 913 clinical isolates of Bacteroides fragilis group organisms were monitored during an 8-year period in Korea. In general the resistance rates of the non-fragilis B. fragilis group species were higher than those of B. fragilis for all the drugs tested. The rate of resistance to clindamycin remarkably increased and those to some beta-lactam drugs such as piperacillin and cefotaxime also increased. No isolates were found to be resistant to imipenem, metronidazole, or chloramphenicol. beta-lactam and beta-lactamase inhibitor combinations and cefoxitin were more active than the other beta-lactams. Therefore, these agents may be considered when empirical selection of antimicrobial agents is required to treat severe anaerobic infections.

In vitro adhesiveness of Bacteroides fragilis group in relation to encapsulation.

The adhesive properties of the B. fragilis group to various erythrocytes were studied by haemagglutination technique and compared to encapsulation. Of the 61 strains of Bacteroides groups tested, only 40 strains of B. fragilis exhibited haemagglutination. Treatment of the organisms with carbohydrates and trypsin had no effect on haemagglutination, but boiling for one hour completely destroyed this property. Haemagglutinating activity of B. fragilis was found to be the highest with chick and tanned sheep erythrocytes. The presence of capsule was observed in 46 strains of B. fragilis group. Of the 40 strains of B. fragilis which exhibited agglutination, capsule was found only in 37. The findings of the study suggest a polysaccharide nature for the adhesin. The different patterns of haemagglutination, suggest the involvement of more than one adhesin. Capsule in capsulated strains and fimbriae in non-capsulated strains might be mediating the property of haemagglutination.

Adherence of bacteroides fragilis strains to a primary cell culture

Foi avaliada a capacidade de aderência de cepas de dBacteroides fragilis a várias linhagens de células de mamíferos. Algumas cepas, definidas como capazes de aglutinar eritrócitos humanso, foram capazes de aderir a células primárias, obtidas de carcaça de cobaio, nas näo às demais células testadas. Apenas uma cepa, näo aglutinante, näo demonstrou qualquer capacidade de aderência às linhagens celulares testadas.