IgG antibodies against anaerobic bacteria in blood donor sera

Fifty-six blood donor sera were examined by indirect immunofluorescence for IgG antibodies to a selection of anaerobic bacterial strains, often isolated from wound cultures. Another 25 sera were examined by IgG antibodies to six NCTC Bacteroides strains. A wide range of IgG antibody titres were found against Fusobacterium, Clostridium, and anaerobic streptococcal species. Very low titres were found against the Bacteroides strains. It is suggested that the testing of a single serum specimen for IgG antibodies against a representative collection of Bacteroides fragilis strains could be helpful in verifying a clinical suspicion of infection with these organisms.