Karen Kvist Christensen

Chlorhexidine for prevention of neonatal colonization with group B streptococci. II. Chlorhexidine concentrations and recovery of group B streptococci following vaginal washing in pregnant women

The effect of a single washing of the urogenital tract with 0.5 g/l chlorhexidine was studied in 6 women in weeks 38-40 of pregnancy, among whom 5 were carriers of group B streptococci in urethra and/or cervix. The chlorhexidine concentrations varied between 25 and 200 mg/l during the first hour after washing in 5 of the 6 women, whereas one patient showed concentrations below 25 mg/l. With the exception of one patient, all individuals showed concentrations less than 25 mg/l at 3-24 h after washing. A clear suppression of the number of colony-forming units of GBS was already apparent after 60 min and was still evident 6 h after chlorhexidine washing.

IgG subclasses and antibodies to group B streptococci, pneumococci, and tetanus toxoid in preterm neonates after intravenous infusion of immunoglobulin to the mothers.

Abstract: High doses of intravenous immunoglobulin were given to seven pregnant women between the 27th and 36th wk of gestation who were at risk for preterm delivery. Determinations of IgG subclasses and of antibodies against group B streptococcal serotypes, pneumococcal polysaccharides, and tetanus toxoid were done in maternal serum before and after intravenous IgG infusion and after delivery in cord serum. Substantial transplacental passage of the infused material could be observed in five cases where delivery occurred at the 34th wk or later. After the 36th wk of gestation, IgG subclass and antibody concentrations in cord serum were increased up to the levels in the maternal serum.

Chlorhexidine for prevention of neonatal colonization with group B streptococci. III. Effect of vaginal washing with chlorhexidine before rupture of the membranes

A single vaginal washing with 2 g/l of chlorhexidine was performed before rupture of the membranes in 19 parturients who were urogenital carriers of group B streptococci (GBS). Two (11%) of the infants became colonized immediately after birth, in contrast to 16 of 41 (39%) infants to controls (P = 0.02). A significant reduction of GBS colonization of the ear (P = 0.02) and umbilicus (P = 0.01) was noted. Taken together, 2 of 57 (4%) cultures obtained at birth were positive in the chlorhexidine group, in contrast to 30 of 123 (24%) among the controls (P less than 0.01). These findings raise hope for the design of a simple washing procedure which might prevent serious infections in the early neonatal period with GBS but also with other chlorhexidine-sensitive organisms.

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.

Colonization of newborns with group B streptococci: relation to maternal urogenital carriage.

Urethral and cervical specimens were obtained from 786 parturients during labour. 126 women (16%) were found to be urogenital carriers of group B streptococci (GBS). Bacteriological specimens were also obtained from the throat, umbilicus and external auditory canal of their 786 infants immediately after birth, and from 671 of the infants staying at the maternity unit 4 days later. 51% (64/126) of the infants born to GBS carriers were culture-positive for GBS immediately after birth. Only 27% (6/22) of the infants born to women who were GBS culture-positive in the urethra but not in the cervix contracted GBS at the delivery, in contrast to 59% (58/85) of the infants born to combined urethral and cervical carriers (P less than 0.05). This difference in colonization rate was not related to differences in levels of antibodies to the type of GBS carried by the individual parturient. On day 4, 13% (90/671) of the infants in the maternity unit were colonized with GBS. 39% of them were colonized at birth from their mother, 12% were culture negative at birth but had become colonized by day 4 with the same type of GBS as that isolated from the urogenital tract of the mother, and 37% were GBS positive on day 4 but culture-negative at birth and the mothers specimens did not reveal GBS. The distribution of serotypes among these infants was identical with that found among the other colonized infants, indicating that they might have contracted their GBS from the other infants in the maternity unit.

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.

Chlorhexidine for prevention of neonatal colonization with group B streptococci. IV. Depressed puerperal carriage following vaginal washing with chlorhexidine during labour.

The effect of vaginal washing with chlorhexidine acetate, 2 g/l at delivery, on the colonization of the urogenital tract with group B streptococci (GBS) 4 days later was investigated. Patients who were culture-positive for GBS in urethra and/or cervix in pregnancy weeks 32 and 36 as well as at delivery were included in a prospective study. The washing procedure was performed in 31 parturients, and 10 (32%) were culture-negative at day 4 after delivery. In contrast, only 7/47 (15%) non-washed controls were negative at day 4 (p = 0.044). The results demonstrate a prolonged suppressive effect of vaginal washing with chlorhexidine on the recovery of GBS from the urogenital tract in this highly selected patient group.

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.

Chlorhexidine for prevention of neonatal colonization with group B streptococci. V. Chlorhexidine concentrations in blood following vaginal washing during delivery

Chlorhexidine 2 g/l was applied to the vagina of 96 women during delivery, whereas 28 served as controls. Both groups were given a shower using a chlorhexidine soap, and outer washing of the outer anogenital tract was also performed in all patients using chlorhexidine 2 g/l. Using a gas chromatographic method with a detection limit of 10 ng chlorhexidine per ml blood, 10-83 ng/ml was demonstrated in 34 (35%) of the study group patients, whereas the remaining study group patients and controls showed no detectable chlorhexidine. Performing the washing a second time after 6 hours in 14 patients and a third time in 3 patients after a further 6 hours did not result in increased serum levels. It was concluded that small amounts of chlorhexidine are absorbed through the vaginal mucosa and that chlorhexidine is not accumulated in the blood on repeated usage with 6 hour intervals during delivery.