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Biomedical subjects

B F Anthony

Publications and source records attributed to B F Anthony.

64 records · Page 4Linked to original sources

Attack rates of acute nephritis after type 49 streptococcal infection of the skin and of the respiratory tract.

Prospective studies in a population of American Indian children during an outbreak of acute nephritis associated with the Type 49 Group A streptococcus permitted a comparison of attack rates of renal complications after infection at different sites and at different ages. Acute nephritis or unexplained hematuria developed in 10 of 42 children (23.8%) with Type 49 streptococcal skin infection, in 2 of 44 (4.5%) with Type 49 throat infection, and in 3 of 16 (18.8%) with simultaneous Type 49 infection at both sites. The higher attack rate of nephritis and hematuria in children with pyoderma indicates that skin lesions played a direct and quantitatively greater role than respiratory infection in the pathogenesis of acute nephritis during this outbreak. Skin infections with the Type 49 strain were followed by evidence of renal complications more often in children younger than 6.5 yr (9 of 21 or 43%) than in older children (1 of 21 or 5%). Attack rates of renal complications after Type 49 skin infection were approximately equal in males and females.

Acute Disease↗

M antigens among group A streptococci isolated from skin lesions.

Three new provisional types of Group A streptococci have been identified among strains isolated from skin infections of American Indian children. A previously established type, Type 41, was also recognized among the pyoderma strains. Most of the skin streptococci with T-agglutination pattern 3/13/B3264 could be identified as Type 41 or as one of two new provisional types, Schoenborn (Type 52) and Hanson (proposed Type 53). Strains of the third new provisional type, Kingbird (proposed Type 54), agglutinated as 15/17/19/23/47, a T pattern not associated with skin infections in studies of other populations. Approximately half of the pyoderma strains examined were found to produce an M antigen; the proportion of M-typable strains from skin infections was found to be similar to that currently found in throat cultures of children with pharyngitis. The demonstration of M antigens in streptococci from skin lesions provides evidence of their potential virulence and should facilitate their classification in subsequent epidemiological studies.

Agglutination Tests↗

Bacterial interference in experimental burns.

A standardized, full thickness, dermal burn in rabbits was used to study interference between strains of Staph. aureus inoculated on the wound surface. Several strains appeared equally capable of colonizing lesions and of preventing superinfection by other staphylococci inoculated at a later time. In addition, cross-infection between rabbits colonized by different strains (502A and Q461) and placed together in cages was prevented, presumably by the same mechanism. Interference appeared to be a strictly local phenomenon, since it did not occur when an animal was colonized by strain 502A at one burn site and subsequently challenged with strain Q461 at a separate lesion. For interference to occur, a minimal time interval (9 hr) was required between inoculation of the interfering strain and inoculation of the challenge strain. In vivo growth rates indicated rapid growth in the first 24 hr by the interfering strain but no detectable multiplication by the challenge strain. Heat-killed staphylococci, even in large numbers, were incapable of producing interference. Penicillin treatment of animals colonized by strain 502A (penicillin-sensitive) abolished interference with strain Q461 (penicillin-resistant). These findings indicate that bacterial multiplication by the interfering strain is an essential feature of this phenomenon. The mechanism of interference between strains of Staph. aureus remains obscure. There was no evidence in these studies for direct bacterial antagonism in vitro or in vivo between most of the strains examined; yet, all were capable of producing interference. Attempts to identify antistaphylococcal activity in passively transferred tissue homogenates and serum collected from infected animals were also negative. The ability of large inocula of staphylococci grown in broth to superinfect colonized lesions indicates that the numerical superiority of the interfering strain over the challenge strain is an important aspect of interference. The observation that in vivo-grown organisms may superinfect in significantly smaller quantities is suggestive of a qualitative advantage as well.

Animals↗

Gram-positive bacteria: an overview and summary of session.

The more pathogenic gram-positive bacteria present a complex array of surface structures to the human or animal host. The cell wall of Staphylococcus aureus has a pattern of surface proteins; the predominant one is protein A. Virulent S. aureus strains may also produce polysaccharide capsules in vivo that impede opsonization and phagocytosis in the absence of anticapsular antibody. Coagulase-negative staphylococci commonly elaborate an exopolysaccharide slime that may promote adherence to plastic surfaces and interfere with host responses. Structure-function relationships for some antiphagocytic M proteins of group A streptococci are now well understood, and recombinant techniques offer the prospect of multivalent vaccines. The best known surface protein of group B streptococci is the c (Ibc) protein, which stimulates protective antibody in animals and may be an important virulence factor. Monoclonal antibodies to types Ib, II, and III group B streptococci have also confirmed the presence of multiple immunodeterminants on these antiphagocytic polysaccharides. A protein on the surface of pneumococci has been shown to induce protective antibody and to enhance pneumococcal virulence in mice, suggesting a potential alternative or adjunct to pneumococcal polysaccharide vaccines. Listeria also possess a variety of cell surface structures important in pathogenesis. Surface components are, therefore, critical determinants of the interaction of gram-positive bacteria with the host.

Animals↗

The role of specific antibody in neonatal bacterial infections: an overview.

Neonatal infections caused by GBS are commonly associated with a deficiency of IgG antibody to the type-specific polysaccharide of the infecting organism. The prevalence and importance of human antibody to specific surface proteins, which are very common in clinical GBS strains, are unknown. Type-specific antibody is sufficiently prevalent that immunoglobulin preparations for both intramuscular and intravenous use contain animal-protective, opsonic antibody for many GBS strains. The availability of polysaccharide vaccines suggest that even more potent, "hyperimmune" preparations can be prepared from immunized volunteers. The importance of selective antibody deficiency in K1 E. coli infections of newborns is less clear. Protective, opsonic antibody is more difficult to demonstrate in human serum, but activity has been shown in some IGIV preparations. The specificity of the active antibody and the feasibility of producing hyperimmune IGIV against K1 E. coli are unknown at this time.

Agammaglobulinemia↗