Search PubMed⌕ Search

Biomedical subjects

H C Dillon

Publications and source records attributed to H C Dillon.

At least 37 records · Page 2Linked to original sources
PubMed1984

Interaction of group B streptococcal type-specific polysaccharides with wheat germ agglutinin and other lectins.

The group B streptococci (GBS) are known to have type-specific polysaccharides rich in N-acetylneuraminic acid end groups, which are thought to be important immunological determinants. Wheat germ agglutinin (WGA) has affinity for N-acetylneuraminic acid as well as N-acetylglucosamine, and readily precipitates the type but not the group polysaccharide. A WGA-Sepharose affinity column was used to isolate complete type polysaccharides of representative strains of the 4 major GBS types. WGA, other lectins, and rabbit antisera were then used to characterize the products of various extraction procedures and chemical degradations, including mild acid hydrolysis and treatment with neuraminidase. Results of lectin binding studies were consistent with proposed chemical structures of types Ia, Ib and II. Differences were noted, however, between the cross-reactive antigens of pneumococcus type 14 and the desialated GBS type III polysaccharide. Although structurally similar, indirect evidence from lectin binding studies suggest that these antigens may not be identical.

Animals↗
PubMed1984

Characterization of the group-specific polysaccharide of group B Streptococcus.

The group-specific polysaccharide of the group B Streptococcus was isolated by nitrous acid extraction followed by gel filtration on Sepharose 6B and chromatography on DEAE-Bio-Gel A. It was composed of rhamnose, galactose, N-acetylglucosamine, and glucitol phosphate. Mild periodate oxidation of the polysaccharide resulted in a rapid reduction in molecular weight, indicating that the glucitol was located in the backbone of the polymer. High-resolution 31P NMR showed the presence of a single type of phosphodiester bond in the molecule. Methylation analysis and several specific chemical degradations were done to determine sugar linkages. The basic structure of the group B polysaccharide consists of a backbone of 2-linked rhamnose, 2,4-linked rhamnose, and glucitol phosphate, and side chains of rhamnose(1----3)galactose(1----3)N-acetylglucosamine linked to the 4-position of a rhamnose in the backbone.

Chemical Phenomena↗
PubMed1983

Protection of mice from experimental infection with type III group B Streptococcus using monoclonal antibodies.

Mouse hybridoma antibodies of several major classes against group B streptococcus type III have been produced. Mice were immunized with either whole heat-killed or acid-treated organisms to obtain antibodies against both the complete (sialated) or incomplete (nonsialated) forms of the type III polysaccharide. Resulting monoclonal antibodies showed exclusive specificity for either the complete or incomplete antigen. The ability of these antibodies to protect mice from a lethal challenge of live type III organisms was tested with a mucin model that permitted use of very small inocula given intraperitoneally with antibody and mucin. Antibodies specific for the nonsialated antigen were not protective, whether of IgM, IgG2a, or IgG3 isotypes. Antibodies specific for the complete antigen were, however, highly protective, including monoclonals of IgM, IgG2a, and IgA isotypes. These mouse monoclonal antibodies against group B streptococci that are directed against either complete or incomplete antigenic determinants, and include isotypes other than IgM, should be particularly useful for studying the mechanism of protection against experimental infection.

Animals↗
PubMed1983

Treatment of staphylococcal skin infections: a comparison of cephalexin and dicloxacillin.

Cephalexin, given twice daily, and dicloxacillin, given four times daily, were compared in a randomly controlled study for the treatment of staphylococcal skin and skin structure infections. Among 70 evaluable patients, 57 had staphylococcal bullous impetigo. The remaining 13 patients had bullous impetigo with streptococcal or mixed streptococcal-staphylococcal cultures (6 patients), abscess (4 patients), or cellulitis with pyoderma (3 patients). Staphylococci were recovered from lesions of 64 of the 70 evaluable patients; all strains were sensitive to both cephalexin and dicloxacillin, but only 2 of the 64 strains were susceptible to penicillin G. Cephalexin and dicloxacillin proved equally effective. Treatment failures were uncommon (1 patient in each group), and recurrences (3 patients in each group) were limited to patients with bullous impetigo. In general, patients with staphylococcal bullous impetigo responded promptly, with clearing of lesions evident within the first week, but delayed healing with persistence of staphylococci in lesions was more common in the group receiving dicloxacillin. Twice-daily dosing with oral antibiotics is obviously convenient and may enhance compliance. Twice-daily therapy with cephalexin for staphylococcal skin and skin structure infections can be recommended with confidence.

Abscess↗
PubMed1983

Epidemiological studies of Streptococcus pneumoniae in infants: development of antibody to phosphocholine.

The pneumococci possess, in addition to type-specific capsular polysaccharides, a number of antigens common to the species. Antibodies to phosphocholine (PC), a major determinant of the C-carbohydrate, have been shown to protect mice from experimental pneumococcal infection, but little is known of the role of anti-PC antibodies in humans or the extent to which anti-PC levels are affected by carriage or infection. We examined 115 sera from 30 infants, who were followed prospectively from birth through 4 years of age, for the presence of immunoglobulin M antibody to PC, using a solid-phase radioimmunoassay method. Infants were found to develop antibody to PC in response to pneumococcal carriage and infection, and nearly all infants developed some antibody. Antibody levels increased with age. By using a regression model including both age and nasopharyngeal carriage of pneumococci, anti-PC levels were found to be highest after exposure to two or three different types of pneumococci; levels were highest soon after acquisition of pneumococci and declined thereafter.

Age Factors↗
PubMed1982

Puerperal and perinatal infections with group B streptococci.

Twenty-one patients were seen with puerperal sepsis owing to group B streptococci (GBS), resulting in an attack rate of 2/1,000 deliveries. Most were young primiparous black women from a population with a known high incidence of GBS carriage. The association among abdominal delivery, endometritis, and puerperal sepsis was striking. Cultures of the birth canal or lochia were commonly positive for the same serotype recovered from the blood. Forty-seven patients with nonbacteremic GBS infections were seen; 27 had endometritis or amnionitis. Twenty patients had GBS urinary tract infection: Eight infections occurred prenatally, seven at delivery, and five post partum. Seven neonates developed serious GBS infections; intrauterine exposure occurred in at least four cases. Fetal exposure to GBS also occurred in three of four cases in which parturients with GBS bacteremia were delivered of their infants by cesarean section. Because of the high incidence of puerperal and perinatal GBS infections in this population, antibiotic prophylaxis regimens may be beneficial.

Adolescent↗
PubMed1982

Anorectal and vaginal carriage of group B streptococci during pregnancy.

A longitudinal prospective study of carriage of group B streptococci during pregnancy was conducted in 2,540 women over a three-year period. Carriage was documented in 18% of the women by anorectal culture, in 4% by vaginal culture, and in 13% by simultaneously obtained anorectal and vaginal cultures (overall carriage rate, 35%). The rate and pattern of carriage were nearly identical from year to year. In sequential cultures in the second and third trimesters of 754 women, carriage rates were 31% and 28%, respectively; only 17% of the women were carriers in both trimesters. (1) Persistence of carriage was most common when the initial anorectal swabs were positive, (2) spread from the intestinal tract to the vagina occurred, and (3) the intestinal tract was commonly the primary site of acquisition in patients with previously negative cultures. The intestinal tract appears to be a primary reservoir for group B streptococci and the likely source of vaginal or urogenital colonization in pregnant women.

Adolescent↗
PubMed1982

Epidemiologic studies of Streptococcus pneumoniae in infants. The effects of season and age on pneumococcal acquisition and carriage in the first 24 months of life.

In a study of the natural history of pneumococcal carriage and infection in infants enrolled at birth in Birmingham, Alabama from November 1974 to December 1975, the authors observed patterns of acquisition and carriage that appeared to be influenced by age and the season of the year. To describe more precisely these effects, the original data were used to construct multiple regression models for acquisition, carriage rates, and duration of carriage of pneumococci during the first 24 months of life. The acquisition rate was strongly seasonal, with a marked winter peak and summer low. Seasonal rate increased with age, while the duration of carriage decreased; these combined effects were reflected in the carriage rate, which increased sharply up to the age of nine months, then leveled off. While age and season accounted for a relatively small part of the variation in acquisition and carriage rates, the models were found to fit the data very well. The authors were able to analyze the data in a precise fashion, confirm earlier observations, and relate them to the work of other investigators over the past 50 years.

Age Factors↗
PubMed1981

A prospective study of group B streptococcal bacteriuria in pregnancy.

Bacteriuria in pregnancy was prospectively studied in 569 women, with specific reference to group B streptococcal infection. Forty-six patients (8%) had bacteriuria, including 14 with group B streptococcal infection; group B streptococci (GBS) were exceeded in frequency only by Escherichia coli. Two thirds of the bacteriuric patients remained asymptomatic. The outcome of pregnancy was studied in 41/46 bacteriuric patients, including all those with group B streptococcal infection. Two pregnancies ended in intrauterine fetal death, and one neonate developed group B streptococcal sepsis; all three complications occurred in the 14 women with group B streptococcal bacteriuria. Diabetes mellitus appeared to increase the risk of group B streptococcal bacteriuria. This study revealed that group B streptococcal bacteriuria is more common in pregnancy than was previously suspected and suggests that culture methods to detect GBS should be used in bacteriuria screening programs done in pregnancy. In terms of perinatal infection risk, screening for group B streptococcal bacteriuria at or near the time of delivery may be more meaningful than other group B streptococcal surveillance culture studies.

Adolescent↗
PubMed1981

Sources and susceptibilities of staphylococci isolated from children. A seven-year survey.

A seven-year surveillance was done of the antibiotic susceptibility of Staphylococcus aureus isolated from patients seen in The Children's Hospital, Birmingham, Ala. There were no outbreaks of hospital-acquired staphylococcal infection during this time. Of 5,479 strains, 2,685 were from hospitalized children; 2,794 of 5,479 were from outpatients. The incidence of penicillin resistance increased from 76% to more than 85% between 1973 and 1979, with no significant difference noted between inpatient and outpatient strains. Penicillin resistance was similar, regardless of the clinical source (site of isolation) of staphylococci. Skin lesions, soft tissue, wounds, and abscess perennially accounted for the greatest proportion of isolates. Thus, skin lesions represent an important reservoir for penicillin-resistant staphylococci. Nearly all strains were susceptible to the other antibiotics tested; multiple resistance was rare. Susceptibility to clindamycin, erythromycin, cephalothin, sodium, and nafcillin sodium remained stable through the years. These agents provide effective therapeutic regimens for patients with staphylococcal infection, including those with penicillin allergy.

Anti-Bacterial Agents↗
PubMed1981

Epidemiologic studies of Streptococcus pneumoniae in infants: antibody response to nasopharyngeal carriage of types 3, 19, and 23.

The relationship between nasopharyngeal carriage of Streptococcus pneumoniae types 3, 19, and 23 and the development of homotypic serum antibody was examined in 17 infants followed prospectively from birth. Serially drawn sera from these children and single serum samples from 18 normal adolescents were assayed for opsonizing antibody using reduction of nitroblue tetrazolium to measure phagocytosis of killed whole pneumococci. Selected sera were also tested for quantitative antibody level by a radioimmunoassay, which correlated quite well with the nitroblue tetrazolium assay. All but one of the adolescents had antibody to type 19, and all 18 had antibody to type 23. None of the 12 infants tested for antibody to type 19 pneumococci showed evidence of an antibody response. Two of 10 infants responded to type 23 pneumococci, as did two of three infants tested to type 3 pneumococci.

Antibodies, Bacterial↗
PubMed1980

Epidemiologic studies of Streptococcus pneumoniae in infants: acquisition, carriage, and infection during the first 24 months of life.

A natural history study of pneumococcal infection in 82 infants followed from birth is reported. Longitudinal carriage patterns were determined by serial throat and nasopharyngeal cultures. Seventy-nine of 82 infants carried one or more types during the study period. The first type was acquired by a mean age of six months, and the duration of carriage decreased with successive types carried. Acquisition of new types peaked in winter months, but carriage rates fluctuated throughout the year. Thirty-one pneumococcal infections were documented in 24 infants: 28 episodes of otitis media, two of bacteremia, and one of meningitis. Types causing disease were similar to commonly carried types (6, 14, 19 and 23). However, infection usually occurred within one month of acquisition of a new type and was seldom associated with prolonged carriage. In terms of exposure to new strains, 15% (31 of 196) of acquisitions resulted in disease.

Age Factors↗
PubMed1979

Streptococcal pharyngitis therapy. A comparison of two erythromycin formulations.

The recommended dosage of erythromycin, without regard to the formulation prescribed, for children with streptococcal pharyngitis is 30 to 40 mg/kg/day. We previously reported an acceptable streptococcal eradication rate among patients with pharyngitis treated with erythromycin estolate, 20 mg/kg/day. In this study, an extension of the earlier one, the efficacy of this same dosage of erythromycin estolate was compared with a 40 mg/kg/day dosage of erythromycin ethylsuccinate. Streptococcal eradication rates were nearly identical in the two groups of patients. The efficacy of erythromycin estolate at a dosage lower than that recommended for children is most likely explained on pharmacologic grounds: better absorption and higher levels in serum and tissue than those achieved with other erythromycin formulations. It seems rational to calculate required dosages of erythromycin on the basis of the formulation being administered.

Antibodies, Bacterial↗
PubMed1979

Serotypes of Streptococcus pneumoniae causing disease.

Serotypes of Streptococcus pneumoniae from 525 infected children were examined over a four-year period. Type distribution was similar among 84 cases of bacteremia and 30 cases of meningitis, with types 6, 14, and 18 accounting for half of the illnesses. In contrast, half of 396 episodes of otitis media were caused by three other types, 19, 23, and 3. Four of eight fatalities were due to type 6. Carrier strains isolated from children had a distribution of types similar to that of the otitis media collection. Adult patients had fewer of the types that caused disease in children. Most childhood infections (80%) occurred in children less than or equal to 24 months of age; no relationship between age and infecting serotype was noted. There were no seasonal trends in type distribution.

Child↗