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K M Boyer

Publications and source records attributed to K M Boyer.

At least 37 records · Page 2Linked to original sources
PubMed1988

Maternal screening in prevention of neonatal infections: current status and rationale for group B streptococcal screening.

Maternal screening--either selective or universal--is an accepted component of a number of strategies for prevention of congenital and perinatal infections. Using the results of maternal screening at prenatal visits and the presence of perinatal risk factors during labour, neonatal group B streptococcal (GBS) early-onset disease can be prevented by selective intrapartum chemoprophylaxis. Possible variations on this strategy may employ semiquantitative tests for GBS colonization at prenatal visits or, possibly, rapid bacterial diagnosis intrapartum. Based on the incidence and economic impact of GBS disease, selective intrapartum chemoprophylaxis appears cost-effective in United States populations, but may not be so in countries with lower incidence rates.

Anti-Bacterial Agents↗
PubMed1988

Antimicrobial prophylaxis of neonatal group B streptococcal sepsis.

This article reviews available studies on prevention of neonatal group B streptococcal infections with antimicrobial prophylaxis. The data show that short-term administration of ampicillin to parturients with prenatal streptococcal colonization and perinatal risk factors effectively prevents these serious infections. A strong case can be made for prenatal screening for group B streptococcal carriage to identify mothers whose babies are at risk.

Anti-Bacterial Agents↗
PubMed1986

Prevention of early-onset neonatal group B streptococcal disease with selective intrapartum chemoprophylaxis.

Most cases of neonatal group B streptococcal disease with early onset have an intrapartum pathogenesis. Attack rates are increased substantially in infants born to mothers with prenatal group B streptococcal colonization and various perinatal risk factors (premature labor, prolonged membrane rupture, or intrapartum fever). In a randomized controlled trial, we studied the effect of selective intrapartum prophylaxis with ampicillin in 160 such high-risk women. In infants born to mothers who received intravenous ampicillin during labor, as compared with controls who received no treatment, neonatal colonization with group B streptococci was present in 8 of 85 (9 percent) versus 40 of 79 (51 percent; P less than 0.001), colonization at multiple (greater than or equal to 3) sites was observed in 3 of 85 (4 percent) versus 24 of 79 (30 percent; P less than 0.001), and bacteremia occurred in none of 85 versus 5 of 79 (6 percent; P = 0.024). The side effects of ampicillin were limited to a single episode of urticaria in a mother who had no history of penicillin allergy. We conclude that intrapartum ampicillin prophylaxis in women with positive prenatal cultures for group B streptococci who have certain perinatal risk factors can prevent early-onset neonatal group B streptococcal disease.

Ampicillin↗
PubMed1986

Human IgG antibody to group b Streptococcus type III: comparison of protective levels in a murine model with levels in infected human neonates.

We determined the serum concentration of human IgG antibody to the native capsular polysaccharide of group B Streptococcus (GBS) type III needed to passively protect mice against lethal homologous challenge. Antibody was measured by an ELISA, standardized by two methods, and corrected for nonprecipitating antibody. A concentration of 1.3 micrograms of IgG antibody to GBS type III/ml protected 126 (97%) of 130 mice from an 80%-96% lethal dose bacterial challenge. Concentrations of IgG antibody to GBS type III in sera from 42 infected infants were less than or equal to 0.3 micrograms/ml. Concentrations of antibody ranged from less than 0.02 to 21.7 micrograms/ml in sera from 102 unselected pregnant women (median, 0.05 microgram/ml); 13% had concentrations greater than or equal to 1.3 microgram/ml. Levels in 25 women colonized with GBS type III who gave birth to normal infants were significantly higher and ranged from 0.1 to 10.7 microgram/ml (median, 0.78 micrograms/ml). In a study of transplacental passage of antibody, protective levels were found in a number of infants with gestational ages between 28 and 36 weeks.

Animals↗
PubMed1984

Type-specific capsular antigen is associated with virulence in late-onset group B Streptococcal type III disease.

Strain differences have been postulated to explain the observation that group B Streptococcus type III (GBS III) late-onset disease occurs in only a fraction of colonized infants. To determine the distribution of type-specific polysaccharide antigen (Ag) in GBS III, Ag was measured by rocket immunoelectrophoresis in both supernatant fluids and EDTA extracts and by radial immunodiffusion in multiple HCl extracts of the pellet from cultures of 10 strains of GBS III. Capsular Ag was defined as the sum of Ag in EDTA extracts + Ag in multiple HCl extracts. Both Ag in EDTA extracts and Ag in supernatant fluids correlated with capsular Ag (r = 0.94). GBS III strains were obtained from the blood of 19 infants with late-onset sepsis, from the cerebrospinal fluid or blood of 22 infants with late-onset meningitis, and from mucosal surfaces of both 18 infants and 12 mothers of infants with low levels of type-specific antibody and asymptomatic colonization. Mean values of Ag in supernatant fluids in strains from infants with late-onset sepsis (1.50 +/- 0.08 micrograms/ml) and late-onset meningitis (1.67 +/- 0.09 micrograms/ml) were significantly greater than those in asymptomatic colonization strains (1.14 +/- 0.05 micrograms/ml; P less than 0.001). The number of organisms required for a 50% lethal dose in the chick embryo, determined in 29 strains, was inversely related to Ag in supernatant fluids (r = -0.60). The demonstration that the quantity of capsular Ag produced by GBS III strains is related to their virulence in chick embryos and to their invasiveness in susceptible infants supports the hypothesis that Ag is a virulence factor in humans.

Animals↗
PubMed1984

Protective levels of human immunoglobulin G antibody to group B streptococcus type Ib.

We studied the concentration of circulating human immunoglobulin G (IgG) antibody to the native capsular polysaccharide of group B streptococcus (GBS) type Ib necessary to protect mice against lethal challenge by laboratory and clinical GBS Ib strains. Antibody was measured by an enzyme-linked immunosorbent assay in which native polysaccharide antigen coupled to human serum albumin was used. The assay was standardized by a quantitative precipitation test, using native antigen and specific human IgG antibody purified by affinity chromatography. IgG anti-GBS Ib antibody level-protection curves for 90% lethal dose challenge of mice were sigmoidal. The curves of whole serum and affinity-chromatographed IgG anti-GBS Ib were superimposable. The serum concentrations of human antibody required for complete protection of mice varied with the infecting strain and ranged from 0.038 to 0.175 microgram/ml. Protective levels of human IgG anti-GBS Ib were lower than those we found previously for homologous protection against GBS Ia challenge (range, 0.25 to 1.0 microgram/ml).

Animals↗
PubMed1983

Isolation guidelines for obstetric patients and newborn infants.

Available isolation guidelines for use in hospitals have often overlooked the infectious diseases and unique interactions of obstetric patients and their newborn infants. To help fill this void, we present our hospital's isolation policies for obstetric and neonatal patients and guidelines for maternal-infant contact and breast-feeding. These policies represent a multidisciplinary consensus of opinion and available epidemiologic data and have been found useful and practical in a single large teaching hospital. Other institutions should be able to adapt these guidelines to their own patient populations, personnel, and physical facilities.

Breast Feeding↗
PubMed1983

Estimation of the protective level of human IgG antibody to the type-specific polysaccharide of group B Streptococcus type Ia.

Human IgG antibody to the type-specific polysaccharide antigen of group B Streptococcus type Ia in the sera of mice was measured by enzyme-linked immunosorbent assay, previously standardized by quantitative precipitation, 24 hr after passive immunization with human serum or affinity-chromatographed antibody. The concentrations of antibody needed to protect mice against 90% lethal dose challenge varied with the bacterial inoculum and ranged from 0.25 to 1 microgram/ml using five strains of group B Streptococcus type Ia. Affinity-chromatographed antibody gave results comparable to serum, indicating the specificity of the antibody and the absence of other humoral factors in protection with this serum. Sera from 11 infected infants and their mothers had concentrations of antibody of less than or equal to 0.17 micrograms/ml, below the protective level delineated in the experimental model. Twelve percent of 50 adult women and 36% of 25 women colonized with group B Streptococcus type Ia had antibody levels of greater than or equal to 1 microgram/ml.

Adult↗