Biomedical subjects
Publications and source records attributed to D C Old.
A series of 25 strains of Providencia spp. produced at least five different patterns of hemagglutination as judged by results from hemagglutination tests in the presence and absence of D-mannose and at least six distinct types of fimbriae as seen from observations with the electron microscope.
Tests for the presence of mannose-sensitive and mannose-resistant, eluting hemagglutinins and fimbriae were helpful in indicating whether biochemically atypical strains of the tribe Escherichieae might be escherichiae or shigellae.
Cultures of Escherichia coli of urinary origin were examined after storage for 12 to 15 years by a combination of the techniques of biotyping, resistotyping, haemagglutinin typing, and colicin typing (multiple typing) which allowed strain identification to be made even when variation in one or more typing characters had occurred in vivo. Biotyping and resistotyping used in conjunction were sufficient to allow identification of as many as 106 of 110 pairs of E. coli examined. In the four pairs of isolates for which it was necessary to extend strain identification profiles to include data from other typing methods, probable strain identification was achieved for all but one pair. The multiple typing approach seems useful for retrospective analysis of stored cultures of E. coli.
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Biotyping by the scheme of Duguid et al. (1975) of 2010 cultures of Salmonella typhimurium received by the Scottish Salmonella Reference Laboratory in 1974--6, the definitive phage types of which were known, revealed 137 different phage type/biotype groups. Four major epidemic clones, comprising 52% of the cultures, were recognized: 1/2a, 49/26a, 56/17g and 141/9f. The sources of each of these four groups of strains were primarily bovine (587 cultures) and human (361), suggesting a close association between infections in the two hosts. Epidemiological evidence showed that most of the outbreaks were caused by cultures of a single phage type/biotype, suggesting that both phage typing and biotyping characters were usually stable in the course of spread of epidemic strains. Thirty-two of the 63 phage types contained strains of more than one biotype. Cultures from 11 of the phage types were of two or more closely related biotypes and those from 21 others were of unrelated or distantly related biotypes. The combined use of phage typing and biotyping made it possible to detect occasional variations in the phage type or biotype in epidemic clones during their spread, e.g. phage type 49 to 204, 56 to 193, 141 to 193 and biotype 2a to 10a, 9f to 9bf, or 9cf, 26a to 26f.
Biotyping provided evidence of the phylogenetic relationships between strains of Salmonella typhimurium of phage types 49 and 204 and certain strains of phage type 193, which were interconvertible in phage types. All of 564 strains of phage types 49 and 204, 35 of which were chloramphenicol-resistant, were of biotype 26 whereas those of phage type 193 (91 strains) belonged to six different primary biotypes. Lines of descent are suggested for strains of phage type/biotype: 193/26a, 193/17g and 193/9f.
A series of 156 cultures of Escherichia coli isolated from sequential urines from 20 patients with urinary-tract infection was examined by biotyping, resistotyping, haemagglutinin typing, O serotyping and antibiogram typing. From 10 of the patients, we repeatedly isolated cultures of a single strain; from each of the other 10 patients, different strains were discriminated. All cultures were typable by biotyping and resistotyping, and those techniques should prove practicable for laboratories not able to perform complete serological analysis. Only a minority (43.6%) of the cultures was typed with a limited range of 24 commercial O sera. Maximum discrimination of strains was achieved by the combined use of several of these techniques.
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meso-Tartrate inhibited the growth of non-meso-tartrate-utilizing strains of Salmonella typhimurium in peptone water media and mineral salts media with some, but not all, carbon sources. C-R intermediates of the tricarboxylic acid cycle or compounds readily converted to them and substrates metabolized independently of the C-6 part of the cycle spared bacteria from the inhibitory effects of meso-tartrate when added to cultures along with meso-tartrate. Experiments with cell-free extracts of non-meso-tartrate-utilizing strains from batch and continuous cultures showed that meso-tartrate was a competitive inhibitor of isocitrate dehydrogenase and isocitrate lyase activities and also inhibited citrate synthase and malate synthase activities. The synthesis of these enzymes was not inhibited by meso-tartrate. The isocitrate enzymes of meso-tartrate-utilizing strains of S. typhimurium were similarly inhibited by meso-tartrate, but inhibition of the growth of meso-tartrate-utilizing strains was demonstrable only in uninduced cultures in which the intracellular concentrations of meso-tartrate were high.
Results from biotyping, resistotyping, hemagglutinin typing, and antibiotic sensitivity testing allowed discrimination of 184 cultures of Escherichia coli and indicated that from each of 20 patients, multiple specimens yielded isolates of a single strain despite the diversity of sites sampled; from each of another 13 patients, strains of different types were isolated. Whereas only 52% of cultures were typed with 24 commerical O antisera, all were characterized by biotyping (27 types) and resistotyping (39 types). Because they identified too few types, hemagglutinin testing (14 types) and antibiogram testing (9 types) were of limited discriminatory value when used alone but aided strain identification when used in conjunction with biotyping and resistotyping. Identification of strains as the same or different is most likely to be achieved by the combined use of several of these systems, each of which may be used in laboratories unable to perform complete serological analysis of strains of E. coli, and we judge that biotyping and resistotyping would provide the most useful information.
The production of fimbriate (Fim+) recombinants was observed in transductional crosses between different pairs of wild-type strains of different biotypes of Salmonella typhimurium. Fim+ recombinants were readily produced in transductions from Fim+ donor strains to Fim- recipient strains and, less frequently, between some pairs of Fim- strains, for example, between almost any strain of the firn biogroup (Fim- Inl- Rha- Bxyl-) and many strains of the non-FIRN Fim- biogroup. None of numerous crosses between different pairs of FIRN strains gave Fim+ recombinants, suggesting that the fim mutation was present at the same intragenic site in all FIRN strains. FIRN strains are thought to have descended from a single ancestral FIRN bacterium which originated by a series of mutations from a strain of the common biotype 1a (Fim+ Inl+ Rha+ Bxyl+). Two FIRN-like (Fim- Inl+ Rha- Bxyl-) strains that did not yield Fim+ recombinants in crosses with FIRN strains were probably wild-type Inl+ mutants from FIRN strains.
Cultures of Salmonella typhimurium (551 strains) of phage type 141 isolated in Scotland from 1965 to 1977 were examined for biotype and colicine type. Three main biotype clones were recognised: If (30 strains), 9f (507 strains) and 31bd (11 strains) with subtype variants 9bf (1 strain), 9cf (1 strain) and 31b (1 strain). The contribution made by each biotype clone to outbreaks in Scotland was analysed. The findings confirmed the distinctness of the three biotype clones within the single phage type and indicated possible origins of strains of biotypes of 9f and 31bd.
We examined the results of tests with 22 substrates for their ability to discriminate a series of 917 strains of Escherichia coli collected from different sources. The tests with three of the substrates were discarded because of difficulties in performance or interpretation, and another nine substrates because they provided little discrimination. The tests used to obtain biotype profiles for strains were those for the fermentation of dulcitol, D-raffinose or sucrose or both, L-rhamnose and L-sorbose, the decarboxylation of L-lysine and L-ornithine, the hydrolysis of aesculin, motility, and prototrophy. Observations on several series of cultures from different sources showed that biotype characters were stable in vivo and after storage on non-selective medium. The biotype profiles obtained were as reliable as partial O serotyping for the routine subtyping of strains of E. coli isolated from the urine of patients with long-term urinary-tract infections and those from other sources in different patients. Biotyping and O serotyping used in conjuction offered a very fine degree of strain discrimination.
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Enzyme studies of strains of Salmonella typhimurium representing biotypes that utilized D-xylose rapidly (xylose strong) or slowly (xylose weak) showed that they were different in the utilization of D-xylose because the xylose-weak strains were deficient in the transport of D-xylose. This observation is consistent with the idea that strains of the different xylose-weak biotypes, e.g. biotypes 17 to 32, were descended from strains of xylose-strong types, particularly from biotype 1.
Fimbriate strains of Escherichia coli K-12 of the AW405 series agglutinated erythrocytes of several animal species. The hemagglutination was mannose senstivie, and the fimbriae were type 1. When cultured for extended periods in static broths, they did not form fimbrial pellicles but formed thick, nonfimbrial pellicles, the appearance of which was not associated with the selective outgrowth of fimbriate-phase bacteria.
The clinical and bacteriological features of a case of endocarditis are described in which a Gram-positive coccus, presently designated Micrococcus sedentarius incertae sedis, was repeatedly isolated.