PubMed Health⌕ Search

Biomedical subjects

M T Parker

Publications and source records attributed to M T Parker.

12 recordsLinked to original sources
PubMed1979

The cultural and biochemical characters of Streptococcus milleri strains isolated from human sources.

A collection of 346 strains of Streptococcus milleri from a variety of human sources was examined culturally and biochemically, and for the presence of Lancefield group antigens. Most of the strains were non-haemolytic and ungroupable, but 25% were beta haemolytic and 19% were alpha haemolytic; 28% possessed a group antigen (A, 5%; C, 6%, F, 14%, G, 3%). These antigens were present in 69% of beta-haemolytic but in only 13% of alpha-haemolytic or non-haemolytic strains; beta haemolysis occurred in 82% of group-F strains, 43% of other groupable strains and 11% of ungroupable strains.The following reactions were given by > 80% of S. milleri strains: hydrolysis of arginine and aesculin, a positive Voges-Proskauer reaction, and acidification of trehalose, lactose, salicin and sucrose. A minority of strains showed enhancement of growth by CO(2), bile tolerance, NaCl tolerance, and ability to acidify other sugars, notably mannitol, raffinose and melibiose. Departures from the modal pattern of biochemical reactions showed a weak correlation with the type of haemolysis and the presence or absence of a group antigen but were not sufficiently systematic for clear-cut subdivisions to be recognized within the species.S. milleri therefore appeared to comprise a ;central' group of non-haemolytic strains that rarely formed a Lancefield-group antigen, in which the aesculin reaction was nearly always positive, lactose was usually acidified, and a considerable minority showed enhancement of growth by CO(2) and bile tolerance. Deviations from this pattern were of two main types. (1) ;Loss' of one or more of these reactions, which tended to be associated with beta-haemolysis and presence of a group antigen. In these respects, alpha-haemolytic strains tended to occupy an intermediate position. (2) ;Gain' of the ability to acidify additional sugars, notably raffinose and melibiose or mannitol; this occurred mainly among otherwise typical non-haemolytic strains that were rarely groupable.Only 12% of isolations from the bloodstream of patients suffering from systemic infections were beta haemolytic and only 18% possessed a group antigen, but a considerably greater proportion of those from visceral abscesses were beta haemolytic (28%). Among isolations from superficial lesions in some body sites there were considerably greater proportions of beta-haemolytic and groupable strains; thus, nearly one-half of those isolated from the abdomen other than the female genital tract were beta-haemolytic and over one-half were groupable. On the other hand, strains from the teeth and gums were nearly always non-haemolytic and ungroupable, and most vaginal isolations were of non-haemolytic strains with a wide sugar-fermentation pattern.

Antigens, Viral↗
PubMed1977

Neonatal streptococcal infections.

Most serious neonatal streptococcal infections are caused by group-B streptococci. The pattern of serious group-B neonatal disease in Britain resembles that described in other countries; both "early-onset" and "late-onset" forms are seen, but reliable incidence rates have not yet been determined. Serological-type III strains predominate in neonatal meningitis in Britain, but not so markedly as in some parts of the U.S.A. A deficiency of group-II strains in meningitis is, however, apparent in both countries. Present information about the carriage of group-B streptococci suggests that antibiotic prophylaxis administered to mothers or infants is unlikely to reduce greatly the frequency of "early-onset" disease. The continuous presence of a suitable chemical disinfectant in the vagina during labour might be more effective. Insufficient is known about the epidemiology of "late-onset" neonatal disease for rational preventive measures to be designed. More information is required about the postnatal acquisition of group-B streptococci by neonates and its sources, and about passive transfer of type-specific antibody from the mother to her child.

Adolescent↗
PubMed1976

Streptococci and aerococci associated with systemic infection in man.

A collection of 820 isolates of streptococci and aerococci from human blood or internal organs was classified by means of a set of cultural and biochemical tests. Of these, 719 (712 streptococci and 7 aerococci) were from patients believed to be suffering from a systemic infection: endocarditis 317; a purulent lesion in an internal organ ("purulent disease") 152; bacteriaemia 250. The endocarditis streptococci included members of all recognisable taxa, but only certain of these were common: Streptococcus sanguis, 16-4%; dextran-positive and usually mannitol-fermenting strains of S. bovis (S. bovis I), 15-1%; S. mutans, 14-2%; S. mitior, 13-2%. Streptococci of the "alpha-haemolytic" taxa (S. sanguis, S. mitior and related strains) formed only 44-8% of the total. When the percentage frequency of streptococcal taxa among the endocarditis and "non-endocarditis" isolates was compared, the dextran-forming taxa (S. mutans, S. bovis I, S. sanguis, and dextran-positive streptococci otherwise resembling S. mitior) all had higher "endocarditis : non-endocarditis" ratios than did any of the non-dextran-producing taxa. Endocarditis increased in frequency with age, and showed an excess of males over females up to the age of 65 years. In young patients (less than 35 years), "alpha-haemolytic" streptococci predominated; with increasing age, the proportion of other streptococci increased progressively but the absolute numbers of isolations of "alpha-haemolytic" streptococci did not fall. Infections with S. mutans were prominent in the age-group 35-54 years and with S. bovis I at ages greater than or equal to 55 years. A history of previous heart disease was more often obtained in endocarditis due to "alpha-haemolytic" streptococci than in other streptococcal endocarditis. The streptococcus most often isolated from purulent lesions in internal organs was S. milleri (29-3%). It was associated with brain abscess, meningitis, pleural empyema and a variety of intra-abdominal abscesses. The only common predisposing factor in endocarditis was previous heart damage. In other systemic streptococcal diseases, other general or local predisposing causes could be observed, mainly in infections with the "pyogenic" groupable streptococci, the enterococci and S. milleri.

Adolescent↗
PubMed1976

Antibiotic susceptibilities of streptococci from the mouth and blood of patients treated with penicillin or lincomycin and clindamycin.

Patients undergoing dental extractions were non-randomly allocated to three groups, one of which received no antibiotic, one benzylpenicillin followed by oral penicillin for 5 days, and the third intramuscular lincomycin followed by oral clindamycin. Dental extraction was performed at the beginning of the course of chemotherapy. Streptococci were isolated from the extracted teeth, from blood cultures collected before and immediately after dental extraction, and from sutures removed from the gums 5-7 days after the operation. The species of these organisms was determined, and their susceptibilities to penicillin, clindamycin, cephaloridine, erythromycin and tetracycline were assessed. The majority of streptococci isolated from teeth belonged to the species Streptococcus sanguis, S. mitior, S. mutans and S. milleri. Occasional isolates of each of these organisms collected before the antibiotic could take effect were resistant to penicillin. Three of these species, but not S. mutans, were the commonest streptococci to be isolated from the blood after dental extraction. Penicillin completely suppressed dental bacteriaemia under the conditions of our investigation, and lincomycin reduced the incidence by about 60 per cent. The commonest streptococci from sutures were also S. sanguis, S. mitior, S. mutans and S. milleri. S. faecalis was also isolated, but only in patients who had received antibiotics. Among the non-faecalis organisms, penicillin resistance was significantly more frequent among isolates from patients given penicillin than from patients not given this antibiotic, and clindamycin resistance was significantly more frequent among isolates from patients given lincomycin and clindamycin than from patients not given these antibiotics.

Anti-Bacterial Agents↗