Nutritional requirements of Bacteroides fragilis and Bacteroides vulgatus with reference to iron and virulence

Growth of Bacteroides fragilis under anaerobic conditions in the presence of either haemin or protoporphyrin IX was inhibited by the ferrous iron chelator bipyridyl. The ferric-iron chelator desferrioxamine inhibited growth in the presence of protoporphyrin but not haemin, suggesting that even under anaerobic conditions Fe3+ is involved in uptake of non-haem iron, which is required in the absence of haemin. However, the ferric iron chelators 1,2-dimethyl-3-hydroxy-pyrid-4-one (L1) and pyridoxal isonicotinoyl hydrazone (PIH) were only weakly inhibitory. Apotransferrin, which also binds Fe3+, inhibited growth, but this was not simply due to binding of iron in the medium, as under the reducing conditions present, transferrin was unable to bind iron. This study suggests that even under anaerobic conditions, uptake of non-haem iron by B. fragilis may involve conversion of Fe2+ to Fe3+.

Section: Introductionmentioning

confidence: 99%

Effect of ferric and ferrous iron chelators on growth of Bacteroides fragilis under anaerobic conditions

Rocha

1991

“…Serum was bacteriostatic for B. vulgatus with iron as a restrictive factor [13]. The higher virulence of B. fragilis was strongly associated with the ability of the strains to grow in serum.…”

Section: Introductionmentioning

confidence: 99%

Ability of bacteroides species to obtain iron from iron salts, haem-compounds and transferrin

Vught¹

1988

Of the five Bacteriodes species of the ‘fragilis group’ only Bacteroides fragilis was able to grow in human plasma. Therefore the capacity of several iron sources to stimulate to growth of Bacteroides species under iron restricted conditions in vitro was tested. The iron chelator bipyridyl was used for the restriction of iron in the media. Ferrous sulphate, ferric ammonium sulphate and ferric citrate stimulated the growth of all five Bacteroides species tested to the same extent. B. fragilis, and to a lesser extent B.thetaiotaomicron and B. distasonis were better able than B. vulgatus and B. ovatus to use haem‐compounds as an iron source in the presence of the iron chelator bipyridyl. All five Bacteroides species tested could use 30% iron‐saturated transferrin. There was no correlation between the ability of the strains to grow in human plasma and the ability to use either haem‐compounds of transferrin as a source of iron.

“…The virulence of the Bacteroides strains was measured by following the clearance of the bacteria from the skin of mice. The details of the model have been described before [5]. In short: approx.…”

Section: Virulence Studiesmentioning

confidence: 99%

“…Of the Bacteroides species belonging to the 'fragilis group', B. fragilis is most often found in human infections, despite its low prevalence in the normal gut flora, and is presumably the most virulent for man [1,3]. In experimental infections in animals, the greater virulence of B. fragilis in comparison to B. vulgatus has been established by several authors [4,5]. The most extensively studied * To whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Nutritional requirements of Bacteroides fragilis and Bacteroides vulgatus with reference to iron and virulence

Vught

1986

The virulence for mice of Bacteroides fragilis is higher than that of Bacteroides vulgatus. This enhanced virulence is related to the higher growth rate of B. fragilis in broth and to the ability of B. fragilis strains to grow in serum. The failure of B. vulgatus to grow in serum could be overcome by addition of haemin and an unidentified growth factor, present in tryptone. Haemoglobin, lysed erythroeytes or iron in combination with protoporphyrin IX could replace haemin.