A serological study of anaerobic curved rods with rabbit hyperimmune antisera

Anaerobic curved rods (ACR) isolated from vaginal discharge of women with a diagnosis of bacterial vaginosis (BV) were investigated with regard to bacteriologic and serologic characteristics. According to morphologic criteria, long curved rods (LCR) which were sensitive to metronidazole, and short curved rods (SCR) which showed resistance to metronidazole, were recognized. LCR degraded several sugars, whereas SCR degraded only a few carbohydrates. With the use of hyperimmune polyclonal rabbit anti-ACR antibodies, heat-labile and heat-stable antigens were demonstrated in whole cells of both LCR and SCR strains by co-agglutination (CoA). Heat-labile antigens which could be flagellae or other surface components seemed to be responsible for inter-group and inter-strain specificity and did not cross-react between LCR and SCR. Two types of heat-stable antigens, one resistant to 120 degrees C, and one resistant to 100 degrees C but not 120 degrees C, were demonstrated in both LCR and SCR. These heat-stable antigens showed considerable one-way and two-way cross-reactivities within the LCR group, and one-way cross-reactivities were also demonstrated between LCR and SCR strains. These cross-reactivities were also demonstrated by indirect immunofluorescence (IFL) in untreated whole cells. The results show that IFL could be used to identify untreated whole cells and CoA to identify heated bacteria.