Viveka Lindén

Obstetrical care in future pregnancies after fetal loss in group B streptococcal septicemia. A prevention program based on bacteriological and immunological follow-up

Among 22 mothers of infants infected with group B streptococci (GBS), 19 showed markedly low levels of antibodies against the infecting type. Three of the patients with low antibody levels went through a new pregnancy within 1 yr after they had lost an infant (2 patients) or experienced fetal death due to GBS (1 patient). They were still urogenital carriers of the type of GBS causing the previous infection, and their serum levels of type-specific antibodies remained low. All three went through a successful pregnancy following a prevention program comprising antibiotic treatment from the 28th wk of pregnancy.

Chlorhexidine for prevention of neonatal colonization with group B streptococci. I. In vitro effect of chlorhexidine on group B streptococci

Forty-three strains of group B streptococci (GBS) of types Ia, Ib, II and III were tested for susceptibility to chlorhexidine in concentrations ranging from 256 to 0.25 mg/l using the agar and tube dilution methods. The strains showed minimum inhibitory concentration (MIC) values ranging from 0.5 to 1 mg/l. Serum added to the test medium (50%) increased the MIC values to 4-8 mg/l, while amniotic fluid (50%) had almost no effect, increasing the values to 1-2 mg/l. The minimum bactericidal concentration (MBC) ranged from 1 to 5 mg/l. The killing kinetics were related to the concentration of chlorhexidine and the length of exposure. For example, at a concentration of 63 mg/l, 7 h were required for a bactericidal effect in broth, as compared to 1 h at 500 mg/l chlorhexidine. 200 mg/l chlordexidine had no effect on the adherence of two GBS strains to vaginal epithelial cells, and no effect on the phagocytosis of GBS with mouse peritoneal macrophages.

Correlation between low levels of maternal IgG antibodies to R protein and neonatal septicemia with group B streptococci carrying R protein.

A method was designed for quantitation of serum antibodies to R protein in group B streptococci (GBS). Four sera from mothers of infants with neonatal septicemia caused by type II, R+ GBS showed a binding range from 400 to 740 cpm in contrast to a range of 690-1,220 cpm in 5 parturients carrying type II, R+ strains in the urogenital tract giving birth to healthy infants (p less than 0.05). The range of antibodies in sera from 8 mothers to infants infected with GBS type III,R+ was 370-750 cpm, whereas the range in sera from 10 carriers of type III,R+ giving birth to healthy infants varied between 510 and 1,280 cpm (p less than 0.01). These findings indicate that R protein is an important virulence factor in neonatal GBS septicemia/meningitis.

Deficiency of IgG Subclasses in Mothers of Infants with Group B Streptococcal Septicemia

Serum IgG subclasses were studied in 19 mothers of infants with serious infections caused by group B streptococci (GBS) and compared with a control group of 20 mothers of healthy infants. 13 of 19 mothers showed decreased subclass levels: 10 of 19 low IgG2, 9 of 19 low IgG1 and 4 of 19 low IgG3. The levels of IgG1, IgG2 and IgG3 were significantly lower among mothers of GBS-infected infants than among the controls. Thus, there is indirect evidence that the infants were immunodeficient at birth.

Mothers of Infants with Neonatal Group B Streptococcal Septicemia Are Poor Responders to Bacterial Carbohydrate Antigens

Serum antibodies against various carbohydrate antigens were studied in 16 mothers of infants with serious infections caused by group B streptococci (GBS) (the study group), and compared with a control group of 29 urogenital carriers of GBS who gave birth to neonatally healthy infants. Using a radioimmunoassay for the determination of antibodies to GBS types Ia, Ib, II and III, it was found that the study group had significantly lower levels of IgG antibodies to each of the 4 GBS types than the control group. The IgG levels against Salmonella BO and DO, Yersinia enterocolitica 03, Francisella tularense and Streptococcus pneumonia types 3, 6, 9, 19 and 23 purified carbohydrate antigens were determined using an ELISA technique. Significantly more individuals in the study group than in the control group had low levels of IgG antibodies against 8 of 9 carbohydrate antigens. No difference was found in IgM levels against 3 of 4 antigens studied, while the study group showed significantly more IgM antibodies against Salmonella DO than the controls. These results indicate that mothers of GBS-infected infants might be poor IgG antibody responders to bacterial carbohydrate antigens in general.

Human IgG Antibodies to Carbohydrate and Protein Antigens in Mouse Protection Tests with Group B Streptococci

Summary: The protective effect of four commercial human gammaglobulin batches (I-IV) in mice was studied using six different strains of group B streptococci (GBS): types la; Ib; II, R-protein negative (R-); II, R+; III, R-; and III, R+. Each mouse received 1.0 ml gammaglobulin and 0.5 ml bacteria, 106-108 colony forming units (CFU). There was a close correlation between antibody levels measured by the use of radiolabeled protein A and the mouse-protective effect of the gamma-globulins. The mouse-protection tests demonstrated that batch I protected against GBS types la and III, R— at low concentration (65 mg/kg mouse weight), against type Ib at medium (260 mg/kg) and against type III, R+ at high concentration. Batch IV protected against types la and Ib, although the doses were four times higher than those in batch I, but did not protect against type III, R+. There was no mouse protection by any of the batches against type II.Antibody levels against Ibc and R, protein antigens, were substantially lower in batch IV. Because the results of these mouse-protection studies indicate the importance of such antibodies against protein antigens, batches I—III might be more useful for therapy of neonatal GBS-septicemia.

Low Levels of Antibodies to Surface Antigens of Group B Streptococci in Commercial IgG Preparations

53 different batches of commercial IgG were tested for antibodies to group B streptococci (GBS) types Ia, Ib, II and III. The levels of antibodies varied widely. Comparison of the anti-GBS antibody levels in these preparations with those found in normal blood donor sera showed that the commercial IgG contained approximately 2.6 times less type-specific antibodies. We conclude that the commercial IgG now available is not optimal for passive immunization against GBS infections in neonates.