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Biomedical subjects

W R Maxted

Publications and source records attributed to W R Maxted.

At least 19 recordsLinked to original sources
PubMed1982

Minimum amount of penicillin prophylaxis required to control Streptococcus pyogenes epidemic in closed community.

The prophylaxis required to control an epidemic of Streptococcus pyogenes throat infection in a junior detention centre has been reported. In a further epidemic an attempt was made to determine the minimum amount of penicillin required to control the outbreak. Oral penicillin (0.5 g) given as a single daily dose for 10 days to all boys after entry proved effective. The added risk of relatively deprived adolescent boys developing rheumatic fever is stressed.

Adolescent↗
PubMed1982

Transduction of the genetic determinant for streptolysin S in group A streptococci.

The genetic determinant for streptolysin S production (SLS+) was successfully transduced to two naturally occurring nonhemolytic strains of group A streptococci (Streptococcus pyogenes), an M-type 18 strain associated with an outbreak of rheumatic fever and an M-negative variant of a type 49 strain isolated from a skin lesion. Attempts to transduce this determinant to a nonhemolytic M-type 68 strain and a nonhemolytic T-type 12 strain were not successful. Transduction was accomplished with a double temperature-sensitive mutant bacteriophage. Cellular antigenic characters and the phage sensitivity of the transductants remained unaltered. The donor strain also transduced streptomycin resistance well when the nonhemolytic type 49 strain was used as a recipient. There was no evidence of cotransduction of the determinants for streptolysin S and streptomycin resistance.

Antigens, Bacterial↗
PubMed1980

Nosocomial transmission of bacteriophage type 7/11/12 group B streptococci in a special care nursery.

Two premature infants in a special care nursery acquired late-onset group B streptococcal (GBS) sepsis within a 24-hour period. The infecting strains were serotype III organisms with bacteriophage type 7/11/12. Cultures of the mothers of the two affected infants were negative for GBS, implying nosocomial acquisition of infection. Although 32% of nursery personnel had mucosal carriage of GBS, none of the seven isolates of GBS type III was the same bacteriophage type as the two infecting strains. Of the other infants hospitalized in the nursery, five were asymptomatically colonized with GBS. These infants were in bassinets adjacent to the affected infants; all five of their isolates were identical to the two infecting strains. We conclude that infant-to-infant transmission may result in nosocomial late-onset GBS septicemia.

Bacteriophage Typing↗
PubMed1980

Streptococcal infection in a Junior Detention Centre: a five-year study.

In 1972 more than 20% of boys admitted to a closed community (Junior Detention Centre) developed acute tonsillitis and group-A streptococci were isolated from more than 40% of all boys at some time during their stay of two months. The most common serotype was M-type 5, which has frequently been associated with rheumatic fever in other epidemics; four cases of rheumatic fever occurred between 1972 and 1977. Various methods were tried to eliminate the infection, but only full penicillin prophylaxis (0.25 g oral penicillin 4 times a day for 10 days) to all boys on entry appeared to be effective. In a sample of cases of acute tonsillitis, group-A haemolytic streptococci were isolated from 31.7% by the use of dry swabs or unenriched transport medium, but with enrichment medium duplicate swabs, 77.6% yielded positive results. We question the current practice in some laboratories of reporting positive cultures only when more than ten colonies of beta-haemolytic streptococci are present. In this survey viruses did not appear to be an important cause of acute tonsillitis. High titres of streptococcal antibodies (antistreptolysin O, anti-desoxyribonuclease B and anti-M associated protein) were found, not only in cases and carriers, but in boys on entry to the centre. This supports epidemiological evidence that adolescent boys are particularly prone to streptococcal throat infections.

Adolescent↗
PubMed1979

Serological grouping of streptococci by slide agglutination.

Streptococcal grouping sera for groups A, B, C, and G prepared for conventional testing by precipitation were made specific by absorption and used to identify streptococci by slide agglutination with and without staphyloccocal coagglutination. Trypsinised suspensions of 1055 strains, identified by precipitation as belonging to group A, B, C, or G, were tested by slide agglutination. Of these, 998 were correctly identified using a streptococcal suspension and antisera alone and a further 65 were identified when a loopful of protein A-positive staphylococci was added. Suspensions of 88 strains not of groups A, B, C, or G gave no reaction in the agglutination test with or without the addition of staphylococci. Group polysaccharide extracted by conventional methods also caused agglutination of staphylococci on a slide when specific antiserum was added. Growth from primary or secondary cultures digested in streptomyces enzyme for only 15-30 minutes provided an excellent antigen for a quick and simple method of streptococcal grouping using non-sensitised staphylococcal suspension and specific antisera for coagglutination.

Agglutination Tests↗
PubMed1977

Inhibition of beta-haemolysis by opacity factor in group A streptococci.

Group-A streptococci belonging to opacity-factor (OF)-positive M types were poorly haemolytic on horse-blood agar, but members of OF-negative M types, and M-negative variants of OF-positive strains gave good haemolysis. Horse-serum extracts of strains of OF-negative serotypes 6 and 12, and M-negative variant cultures of OF-positive serotypes 4 and 49, had higher titres of streptolysin S than did similar extracts of OF-positive, M-positive cultures of types 4 and 49. However, much larger amounts of streptolysin S could be extracted with ribonuclease (RNAase)-digested yeast ribonucleic acid (RNA) and M-positive OF-positive cultures treated in this way gave extracts at least as strong as did their M-negative variants or the OF-negative strains. Extraction of streptolysin S from OF-negative strains by serum could be inhibited by previous incubation of the serum with extracellular OF, suggesting that the production of diffusable OF by M-positive variants of OF-positive serotypes interferes with the extraction of streptolysin S by serum and leads to poor haemolysis on blood agar. The haemolysis of all strains on blood agar was greatly improved by the incorporation of 0-1% (w/v) RNAase-digested yeast RNA into the medium, but the improvement was most marked in OF-positive serotypes.

Hemolytic Plaque Technique↗
PubMed1976

Immunological heterogeneity among the M-associated protein antigens of group-A streptococci.

Different serotypes of group-A streptococci share common antigens that are closely associated with the type-specific determinant of M protein. By the use of selected human sera containing antibody to these M-associated antigens, we have shown that group-A streptococci can be divided into three categories. The majority of the opacity-factor-negative respiratory serotypes possess a shared M-associated antigen or antigens, to which high titres of antibody are common in patients with rheumatic fever, or patients recovering from upper respiratory infections with certain opacity-factor-negative serotypes. The antibody in these sera has a demonstrable but limited affinity for the M-associated antigens of strains belonging to a second category of M types, the majority of which are opacity-factor-positive serotypes of "throat" or "skin" origin. A third group, consisting mainly of opacity-factor-negative pyoderma serotypes, gave variable results and seemed to be intermediate between the other two categories. Complement-fixation-inhibition tests and absorption studies showed a marked degree of cross-reactivity between the M-associated antigens of the three categories.

Acute Disease↗
PubMed1976

Further studies of some "nontypable" group A streptococci.

Thirty-two strains of group A hemolytic streptococci which could not be M typed with the available typing sera in Nashville, Tenn., were reinvestigated at the Streptococcus Reference Laboratory in Colindale, England, in order to estimate the efficacy of other antisera not available in Nashville and newer techniques (the opacity factor inhibition test) of typing strains not isolated in England. Fifty percent were eventually typed and all but four contained enough M protein to suggest that they would have been typed had the appropriate typing sera been available. The results indicate that group A streptococci truly lacking M protein were seldom isolated from the Nashville children from whom the streptococci were cultured. Several factors responsible for nontypability were considered, including the nonavailability of the necessary type-specific antisera and loss of M protein due to a change from Matt to glossy colonial types in the laboratory.

Animals↗
PubMed1975

Outbreak of idiopathic erysipelas in a psychiatric hospital.

In an outbreak of idiopathic erysipelas ten women patients, aged 42-74, in a long-stay unit of a psychiatric hospital were simultaneously affected. Group A streptococci M-type 1 were isolated from two isolated from two patients with erysipelas and 18 carriers, but subsequent serological tests for type-specific antibody, antistreptolysin O, and anti-deoxyribonuclease B showed that the infection had been widespread in the unit. Treatment with ampicillin proved ineffective and to prevent relapse it was substituted by a standard course of intramuscular penicillin. This seems to be the first epidemic of this type to be reported and certainly the first outbreak of idiopathic erysipelas to be investigated by modern serological techniques.

Acute Disease↗
PubMed1974

An outbreak of streptococcal sore throat and rheumatic fever in a Royal Air Force training camp; significance of serum antibody to M-associated protein.

A large outbreak of streptococcal sore throat in a Royal Air Force Training Camp resulted in five cases of rheumatic fever among the 16- to 18-year-old apprentices, and one case in a 33-year-old airman. The most prevalent type of group A streptococcus isolated from throat swabs was M-type 5 and there was serological evidence that at least four of the rheumatic fever (R.F.) cases were due to this type.Among the patients with uncomplicated throat infection the anti-streptolysin O (ASO) and anti-deoxyribonuclease B (anti-DNAase B) responses were in general rather low, even where there was evidence of protective antibody against type 5. However, a combination of the results of the ASO and anti-DNAase B tests gave an estimate of the extent of streptococcal infection 15-25% higher than did either test alone.The titres of antibody to M-associated protein (MAP) were >/= 60 in all the R.F. patients, and in about 50% of the other patients with ASO titres >/= 200. This figure is unusually high compared with data from several other outbreaks of streptococcal infection due to different serotypes and also greatly exceeds comparable figures for cases of sporadic sore throat and acute glomerulonephritis.

Adolescent↗
PubMed1973

Antibody to streptococcal opacity factor in human sera.

Two tests are described for detecting antibody to the type-specific opacity factor (OF) of group A streptococci. This antibody was detected among patients convalescent from streptococcal sore throat in two communities in which outbreaks due to opacity factor-producing strains of group A streptococci occurred.In an outbreak due to streptococci of M-type 22 there was a close correspondence between the distribution of anti-OF and of bactericidal M-antibody for the type. In a smaller outbreak due to M-type 58 streptococci, however, M-antibody was detected more often than antibody to OF.

Animals↗