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Biomedical subjects

R S Baltimore

Publications and source records attributed to R S Baltimore.

11 recordsLinked to original sources
PubMed1992

Infective endocarditis in children.

IE in children is associated primarily with underlying congenital structural heart lesions, predominantly septal defects or complex lesions involving septal defects. During the past 20 years IE associated with rheumatic heart disease has declined to a negligible number. Recently nosocomial catheter-associated bacteremia has been associated with the development of IE, especially in infants. Streptococci are most frequently associated with IE involving natural valves. Although streptococci have also been implicated in cases of IE associated with previous surgery or catheter-related infection, staphylococci, Gram-negative rod species and multiple infecting species are also encountered in this setting. Because infection can often be managed medically, removal of grafts or prosthetic valves is not necessary unless clinical or microbiologic failure occurs. Penicillin with or without an aminoglycoside is the regimen for most community-acquired streptococcal IE. A penicillinase-resistant beta-lactam generally is substituted for penicillin in IE caused by an unknown agent and is used in cases of staphylococcal IE. For IE caused by resistant staphylococci, vancomycin is the alternative agent. Currently there is limited information on the efficacy of alternative agents for treating IE caused by enterococci or staphylococci with multiple antibiotic resistance.

Anti-Bacterial Agents↗
PubMed1979

Immunodeterminant specificity of human immunity to type III group B streptococcus.

The type III polysaccharides of group B Streptococcus in its native state chemically consists of glucose, galactose, glucosamine, and sialic acid. The core of this polysaccharide lacks sialic acid and precipitates with type III antiserum to give a partial identity with the precipitate between the native antigen and this serum. The core determinant is immunochemically similar to the capsular polysaccharide of type XIV Streptococcus pneumoniae, while the native type III group B streptococcal polysaccharide does not cross-react with type XIV pneumococcal antiserum. In human sera, it is antibody directed to the native antigen which correlates very highly with opsonic immunity (r = 0.94) while a poorer correlation exists between antibody to the core antigen and opsonins (r = 0.51 P less than 0.001). In natural infections, as association exists between low levels of maternal antibody to the native antigen and risk of disease in the infant. This association is not true for antibody to the core structure, where both infected infants and their mothers have much higher levels of antibody to the core than the native antigens. Infected infants are also more likely to respond to infection by developing antibody to the native antigen. Immunization of 12 adults with multivalent pneumococcal polysaccharide induced significantly better antibody response to the core antigen than to the native, and this vaccine induced opsonic activity in only one recipient. Immunization of adults with type III group B streptococcal antigens induced antibody to the native determinant which correlated with opsonic activity. Therefore, it would appear that native group B streptococcal polysaccharides will provide the best candidate antigens for immunization.

Antibodies, Bacterial↗
PubMed1979

Mouse protection test for group B Streptococcus type III.

The mouse model has been used previously for the study of protection against challenge with strains of group B Streptococcus types Ia, Ib, and Ic, but investigators have not yet been successful in causing lethal disease when type III strains are inoculated. In this study, six clinical isolates belonging to serotype III were lethal in seven-week-old outbred albino mice; the 50% lethal dose (LD50) for mice tested ranged from 1.8 x 10(4) to 4.6 x 10(6). In contrast, a laboratory prototype strain of serotype III was not lethal. The lethality observed with this protection test depended on both the volume of the inoculum given and the medium in which the streptococci were suspended. LD50 values decreased as the volume of the inoculum, given intraperitoneally, increased, up to a volume of 1.5 ml. Hyperimmune rabbit antiserum to a clinical isolate of type III protected mice against an estimated 90% lethal dose of the isolate. Normal rabbit serum and heterologous antisera, except for one of two antisera to type Ia organisms, were not protective. Absorption of type III antiserum with whole organisms of serotype III or with purified, type III-specific polysaccharide inhibited protection of mice against type III organisms.

Absorption↗
PubMed1977

Meningococcal bacteremia: clinical and serologic studies of infants with mild illness.

We report three mildly ill infants who had meningococcal bacteremia and in whom meningitis or fulminant septicemia never developed. The infants were observed during a three-month period. Two of these infants had pneumonia, as evidenced by infiltrates on chest roentgenogram. The serogroups of the organisms isolated were B, Y, and 135. In none of the infants could specific bactericidal antibody be demonstrated in acute or convalescent serum.

Animals↗
PubMed1977

Antigenic specificity of opsonophagocytic antibodies in rabbit anti-sera to group B streptococci.

An opsonophagocytic assay has been developed which requires human polymorphonuclear leukocytes, immune serum, and complement for optimal killing of Group B streptococci. Only with all three of these components was killing of greater than 1.0 log10 of the initial inoculum achieved, using rabbit antisera directed to homologous strains of each of the five known serotypes of Group B streptococci. Titers of specific antisera which opsonized the strains and resulted in greater than 1 log 10 reduction of colony-forming units, ranged from 1:100 (serotype Ib) to 1:3200 (serotype Ia). Cross-reactions between serotype-specific sera and heterologous strains were seen in certain instances. Type Ic strain and serotype Ic antiserum demonstrated cross-reactions with types Ia and Ib which were explainable by known shared antigens among these types. The only other cross-reaction which resulted in greater than 1 log 10 reduction in colony-forming units was when unabsorbed antiserum to strain Ia was used to opsonize a strain of serotype III. Opsonization of 10 serotype III strains was demonstrated with a single type III antiserum. Killing of nine of these strains required polymorphonuclear leukocytes, complement, and antiserum, but one strain, D136C, the reference strain, could be killed (greater than 1 log 10 reduction in colony-forming units) without either complement or specific antiserum. Inhibition studies were performed utilizing large m.w. polysaccharide antigens extracted from each serotype. These antigens inhibited opsonization of homologous strains by homologous antisera with 50% inhibition points ranging between 0.5 and 4 mug.

Animals↗
PubMed1976

Perichondritis of the ear as a complication of acupuncture.

A 54-year-old woman developed pain, tenderness, and swelling at the site where a short acupuncture needle had been placed in the helix of the pinna. Staphylococcus aureus was isolated from this LESION. Which was treated with removal of the needle and intravenously administered nafcillin. The patient recovered completely and had no scarring.

Acupuncture Therapy↗
PubMed1976

Synergy of mecillinam (FL1060) with penicillins and cephalosporins against Proteus and Klebsiella, with observations on combinations with other antibiotics and against other bacterial species.

Thirty-five strains each of Klebsiella and Proteus were tested for susceptibility to mecillinam alone and in combination with ampicillin, carbenicillin, cephalothin, and cefazolin. Antibiotics were considered to be synergistic when there was a >/=fourfold reduction in minimum inhibiting concentration of both antibiotics in the combination as compared with that of each antibiotic alone. Synergy of mecillinam with ampicillin, carbenicillin, cephalothin, and cefazolin was demonstrated against 2, 3, 7, and 8 of the 35 strains of Klebsiella and against 14, 14, 19, and 24 of the 35 strains of Proteus, respectively. Synergy against the isolates of Proteus was related to species, whereas against Klebsiella it was related to susceptibility of the isolates to mecillinam. Tests of combinations of mecillinam with other antibiotics on the same and different species indicated that synergy was related to the antibiotic, the species, and the strains of organisms tested.

Anti-Bacterial Agents↗
PubMed1975

Coxsackievirus B5 infection and aseptic meningitis in neonates and children.

In metropolitan Washington, DC, an outbreak of aseptic meningitis in children was recognized in the summer and fall of 1972. Age-specific attack rates were highest in children less than 1 year of age. The incidence of cases showed two peaks: one in July and another in October. Coxsackievirus B5 was associated with cases occurring in July, August, and September, but was not implicated in the October cases. Seventy-six percent of the confirmed coxsackievirus B5 infections in aseptic meningitis patients occurred in infants less than 2 months old. Specific meningeal symptoms were less frequently observed in these young infants, although viral isolations were more common (13 of 15) compared to patients over 2 months of age (four of 19). Analysis of reported coxsackievirus B5 infections in Washington, DC, and the United States as a whole suggests a five- or six-year periodicity.

Adolescent↗