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Biomedical subjects

J R Tagg

Publications and source records attributed to J R Tagg.

At least 55 records · Page 3Linked to original sources
PubMed1987

Suspected periodontopathic microorganisms and their oral habitats in young children.

Samples of subgingival plaque from 67 children, 5-7 years of age, were examined for the presence of certain suspected periodontal pathogenic species using the conventional technique of anaerobic sonification, dilution and spiral plating. When this technique was compared with a direct plating procedure which involved no preliminary dispersion and dilution of plaque specimens, it was found that the direct method resulted in double the frequency of children in whom black-pigmented Bacteroides (BPB) were detected and a 10-times increase in the number of subjects harbouring Actinobacillus actinomycetemcomitans. Samples from the tongue, tonsils and saliva were also plated using the direct technique. BPB were detected less commonly in the plaque specimens (61.3% of children) than in saliva (89.5%), or on the tongue (86.6%) and tonsils (97.1%). Expressed as percentages of a pooled sample of the total BPB population, the most frequently detected species in plaque were Bacteroides intermedius (44.4%) and Bacteroides melaninogenicus (48.0%). The most prevalent isolate in all other oral sites was B. melaninogenicus. Expressed as percentages of children in whom BPB were detected, the most frequently isolated species from plaque using the conventional dilution technique was B. intermedius (21.3%), whereas other BPB species were present in fewer than 5% of children. Fusobacterium nucleatum and Capnocytophaga species were isolated most frequently from plaque but were also commonly detected in the various other oral sites.

Aggregatibacter actinomycetemcomitans↗
PubMed1987

Bacteriocin-like inhibitory activity associated with beta-hemolytic strains of Streptococcus salivarius.

Seven beta-hemolytic Streptococcus salivarius isolates produced bacteriocin-like inhibitory activity in deferred antagonism tests using a set of nine indicator bacteria (I1-I9). Five of these S. salivarius strains (KWF, TOVE-R, K17, K21, and K26) were inhibitory to indicators I2, I5, I6, and I7. Mutated non-hemolytic derivatives showed concomitant loss of inhibitory activity against I2, I5, and I6, but retained activity against I7. Inhibitory activity against I2, I5, and I6 was restored in beta-hemolytic revertants of such mutants. Strain 3638 was inhibitory to all of the indicator organisms except I3, and this pattern of inhibitory activity was retained by non-hemolytic derivatives. It appeared that strain 3638 produced an additional broadly-active inhibitory agent, since a mutant (strain 3638A), which was apparently defective in the production of this inhibitor, retained both the beta-hemolytic and I2-, I5-, I6-, and I7-inhibitory activities. Non-hemolytic derivatives of strain 3638A were inhibitory only to I7. Strain 3638, therefore, appeared to produce at least three inhibitory agents: one active only on I7; another acting on I2, I5, and I6 (and associated with beta-hemolytic activity); and a third apparently active on all of the indicators other than I3. S. salivarius strain JH inhibited all nine indicator strains and possessed a beta-hemolytic character which differed from that of the other strains in being readily eliminated on treatment with the plasmid-curing agent novobiocin. Non-hemolytic derivatives of JH retained inhibitory activity against the complete set of indicators.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriocins↗
PubMed1986

An inhibitor typing scheme for Streptococcus uberis.

A typing scheme was used to test 15 strains of Streptococcus uberis according to their production of (P-type) and sensitivity to (S-type) bacteriocin-like inhibitory substances. Twelve of the strains were inhibitor producers and nine different P-types were detected. All of the strains were typable according to inhibitor sensitivity, ten different S-types being distinguished. Both the P-type and S-type designations of the strains were reproducible on repeated testing. By combination of P-typing and S-typing, highly discriminatory inhibitor 'fingerprints' of the strains could be obtained. This scheme would appear to have considerable potential for typing isolates of Str. uberis as an aid to investigations into the epidemiology of Str. uberis mastitis in dairy cattle.

Animals↗
PubMed1986

Proteinase-related broad-spectrum inhibitory activity among group-A streptococci.

Some 10% of group-A streptococci have inhibitory activity against all nine strains (eight of them streptococci) in a set of indicators in an inhibitor-production typing (P-typing) scheme. This activity was associated with the concurrent synthesis of cell-associated proteinase by the streptococcal strain. Inhibitor production was prevented either by incubation of the test strain in conditions inimical to proteinase production, e.g., at low temperature and alkaline pH, or by addition to the medium of substances, such as glucose, iodoacetic acid, lincomycin, Congo red or trypan blue, that had an anti-proteinase effect. Inhibitory activity was not detectable in liquid cultures, but freeze-thaw extracts of cultures of group-A streptococcus strain A1013 on Gibco Columbia Agar Base (Gibco Diagnostics, Madison, WI, USA) had some inhibitory activity. The inhibitor was concentrated and partially purified, and the active agent was shown to be a high-mol.-wt cationic protein which was bactericidal for various bacteria in the logarithmic growth phase, including the homologous producer strain.

Antibiosis↗
PubMed1986

Role of proteinase in the formation of inhibitory levels of hematin by group A streptococcus cultures on blood-containing media.

Group A streptococci were tested for proteinase production and for the possible relationship of this production to the generation of bacteriocinlike inhibitor activity. Of 126 strains tested, 83% were positive for proteinase, and a similar distribution was found among strains isolated in association with rheumatic fever (89%) and nephritis (94%) and from uncomplicated acute infections (78%). Although application of an inhibitor production (P) typing scheme demonstrated a variety of P types, all of the proteinase-positive strains produced inhibitory activity and over 65% of these strains were P type 204. It was shown that hematin was responsible for this P type 204 activity and that it was produced only by actively proteolytic strains when grown on a hemoglobin-containing medium. Conditions optimizing proteinase production (anaerobic incubation at 37 degrees C on a test medium prepared from Columbia agar base [GIBCO Laboratories, Grand Island, N.Y.]) increased P type 204 activity. Interference with proteinase activity either by growth of the cultures at an alkaline pH or by incorporation of sub-growth inhibitory concentrations of either iodoacetic acid or lincomycin into the medium prevented production of P type 204 activity. Whether significant conversion of hemoglobin to hematin occurs in vivo and the possible implications of this conversion with regard to the pathogenesis of group A streptococcal infections remain to be determined.

Blood↗
PubMed1986

Incidence and characterization of anti-microbial effects produced by Actinomyces viscosus and Actinomyces naeslundii.

Sixty-two facultative Actinomyces strains isolated from dental plaque were tested for the production of bacteriocin-like inhibitory effects by a deferred antagonism method. When incubated anaerobically, all isolates produced identical inhibitory patterns against 15 indicator organisms, but under microaerophilic conditions, little inhibitory activity was observed. Activity was not evident after anaerobic incubation on a medium buffered by 0.5% (w/v) calcium carbonate. Gas-liquid chromatographic analyses of agar blocks removed from the inhibitory zones indicated that, compared with microaerophilic conditions, anaerobic incubation encouraged production of high concentrations of lactic and succinic acids, and the concomitant fall in the pH was probably responsible for the inhibitory effects.

Acids↗
PubMed1985

Production of broad-spectrum bacteriocin-like activity by group A streptococci of particular M-types.

Application of a bacteriocin production (P)-typing scheme to group A streptococci has shown that approximately 10% of the tested strains inhibit the growth of all 9 indicator bacteria, an activity referred to as P-type 777. Production of such activity was found to be restricted to 14 M-serotypes and within these M-types the incidence of P-type 777 activity was very high. There was no evidence of any correlation with the T-antigenic composition of the bacteria. Investigations of the conditions for production of P-type 777 activity and of its spectrum of activity indicate that the same inhibitory substance(s) are responsible for this inhibition in the various M-types of streptococci. Group C streptococcus strain T277 produces an inhibitor which has a similar activity spectrum to that of the P-type 777 group A streptococci, but there were considerable differences in the production conditions. Whereas the group C inhibitor was particularly dependent on conditions of incubation (37 degrees C, anaerobic) the group A activity was more dependent on the composition of the test medium (source of blood agar base and blood requirement). All of the tested P-type 777 group A streptococci had identical inhibitory spectra. This was principally directed against gram-positive bacteria, including the producer strains themselves. Of interest was the occurrence of some insensitive strains in otherwise susceptible species of bacteria and the discovery of one sensitive gram-negative strain, Bacteroides intermedius. Production of P-type 777 activity does not appear to correlate with production of various streptococcal enzymes, including protease, hemolysin, DNase and amylase. Many P-type 777 strains are producers of opacity factor, another M-type-associated product of group A streptococci. It is suggested that by the combined testing of group A streptococci for P-type 777 activity and for opacity factor it would be possible to narrow the choice of M-antisera to be used for typing purposes.

Amylases↗
PubMed1985

An inhibitor typing scheme applicable to Lancefield group E streptococci.

A previously described inhibitor typing scheme for hemolytic streptococci has been utilized to test 12 well-characterized strains of group E streptococci. These strains were differentiated into five inhibitor production (P) types and four inhibitor sensitivity (S) types: seven different strain "fingerprints" (combinations of P-type and S-type) being demonstrated. Inhibitor production by group E streptococci was increased under conditions of anaerobic incubation. The inhibitor fingerprints were stable on repeated testing of strains and it is suggested that the scheme is of value both for the labelling of serologically untypable strains and for subdividing strains belonging to existing serotypes.

Anaerobiosis↗
PubMed1984

A bacteriocin produced by certain M-type 49 Streptococcus pyogenes strains when incubated anaerobically.

Bacteriocin production (P)-typing of 75 M-type 49 group-A streptococci obtained from a variety of epidemiological incidents in different countries gave no evidence of production under the usual aerobic test conditions. However, with anaerobic incubation, 28% of the strains gave a pattern of inhibitory activity against the indicator strains which was indistinguishable from that previously attributed to the bacteriocin, streptococcin A-FF22 (SA-FF22). Isolation and partial purification of the M type 49 bacteriocin (SA-M49) by freeze-thaw elution from anaerobically grown lawn cultures, followed by ammonium sulphate precipitation and Sephadex chromatography, showed the activity to be associated with a heat-stable proteinaceous molecule of molecular weight approximately 8000 - properties similar to those of SA-FF22. SA-FF22 and SA-M49 were found to have identical inhibitory spectra including immunity of the producer strains to the inhibitory activity of both the homologous and heterologous bacteriocin preparations. SA-M49 production occurred in some strains of phage subtypes II, III and provisional VI and, since it was a consistent property for all isolates from single outbreaks of infection, it provides a means of discriminating between strains of each of these three phage subtypes. There was no evidence of any increased incidence of SA-M49 production in M-type 49 strains associated with nephritic sequelae.

Anaerobiosis↗
PubMed1984

Production of bacteriocin-like inhibitors by group A streptococci of nephritogenic M types.

Application of a bacteriocin-typing scheme that had been designed to minimize the inhibitory effects of hydrogen peroxide and acidic metabolites demonstrated a high incidence (72%) of bacteriocin-like inhibitors belonging to 5 different production (P) types in 61 strains of group A streptococci isolated in association with the development of acute glomerulonephritis. By contrast, only 4 of 16 (25%) rheumatic fever-associated strains were inhibitor positive, and 3 of these strains were P type 604, a P type not detected in any of the nephritis isolates. The P type designation was found to be identical for all inhibitor-positive strains within each particular M serotype, regardless of whether the source was a nephritis patient or an individual having an uncomplicated streptococcal infection. The incidence of inhibitor-positive strains was particularly high in strains of M types 2, 4, 12, 25, 57, and 60; it was moderately high in M types 49, 52, and 55 and absent in M1 and M3. Although the results indicate that the bacteriocin-like inhibitors detected in this study are probably unlikely to have a direct pathogenetic role in either rheumatic fever or acute glomerulonephritis, it does seem that the present P-typing scheme is a useful epidemiological tool, particularly for the presumptive identification of and differentiation among group A streptococcus strains of nephritogenic serotypes.

Aerobiosis↗
PubMed1984

Evaluation of a typing scheme for group A streptococci based upon bacteriocin-like inhibitor production.

A method of typing (P-typing) streptococci according to their production of inhibitory activity against a set of 9 indicator strains has been evaluated. Modifications to a previously described P-typing procedure have been made which improve the reproducibility of the method and also reduce the proportion of untypable strains. The test conditions, particularly medium composition, incubation temperature and aeration were found to be critical determinants of inhibitor production and must be carefully controlled. The use of certain commercial sources of Blood Agar Base and the presence of human blood in the typing medium are requirements for detection of some inhibitors, particularly for P-type 777 strains. The previously "standardized" conditions for P-typing specify incubation of the test strains aerobically at 32 degrees C. However, in order to increase the proportion of typable strains an additional set of cultures should be incubated anaerobically. Anaerobic incubation was found to be essential for the production of bacteriocin-like inhibitors by M-type 49 strains and markedly increased inhibitor production by M-type 4 and M-type 57 strains. Also associated with anaerobic incubation was an increase in the amount of non-specific, acid-mediated inhibition, but this could be eliminated by buffering the typing medium with 0.5% (w/v) calcium carbonate. The epidemiological validity of P-typing was tested in a survey of group A streptococcus carriage in a school and in 9 family groupings. Inhibitor production appeared to be a stable strain marker and the occurrence of some P-type subdivisions within clusters of strains having identical serotype patterns indicates that combined application of serotyping and P-typing may give improved strain discrimination.

Bacteriocins↗
PubMed1983

Application of inhibitor typing in a study of the transmission and retention in the human mouth of the bacterium Streptococcus salivarius.

Inhibitor production (P)-typing was used as a strain marker in epidemiological studies of Streptococcus salivarius. 43 per cent of 180 adult subjects had inhibitory Strep. salivarius strains as components of their oral microbiota. Strains of 13 different P-type patterns were detected and strains of different P-types often co-existed in the same subject. Adults from whom inhibitor-producing Strep. salivarius strains had been isolated retained their characteristic bacteriocinogenic strains over a 3-yr period. A specific Strep. salivarius-inhibitor screening method was used to study oral acquisition of Strep. salivarius by 14 newborn babies. Initially the babies were colonized by a wide variety of strains, many of which were not detected in the mothers' mouths. By the fifth day of life, strains with P-types identical with those in the mother had often become established as quantitatively prominent members of the babies' Strep. salivarius population.

Adult↗
PubMed1983

Bacteriocin-like activity of group B and group C streptococci of human and of animal origin.

An inhibitor "fingerprinting' technique was used to test 120 group B and 50 group C streptococcus strains for production of inhibitory activity. The incidence of inhibitor production was low. Five of 70 group B streptococci of animal origin and one of 50 from human sources consistently produced inhibitory activity. Six of 20 animal strains and three of 30 human strains of group C streptococci were inhibitor producers. These included two Streptococcus dysgalactiae, three S. equisimilis and four S. zooepidemicus. The temperature of incubation and species of origin of the blood used in the culture medium were critical determinants of inhibitor production. Investigation of inhibitors for their spectrum of activity, heat stability, sensitivity to trypsin, dialysability and mode of action indicated that five of the group B and seven of the group C streptococci produced inhibitors that had bacteriocin-line properties. Three bovine strains of group B streptococci produced very similar inhibitory activity. A greater variety of bacteriocin-like substances was detected in the group C streptococcus strains. Two of the S. zooepidemicus strains were each found to produce more than one inhibitory substance.

Anaerobiosis↗
PubMed1983

Inhibitor production by group-G streptococci of human and of animal origin.

Strains of group-G streptococci were tested by a "fingerprinting" method for the production of (P typing) and sensitivity to (S typing) inhibitory agents, and were biotyped. In the standard P-typing test, 28 of 50 strains of human origin, but none of 30 strains of animal origin, showed inhibitory activity. Of the human strains, 12 formed a bacteriocin that was active on group-A streptococci, including three (strains I2, I5 and I8) of the four streptococci of this group among the indicator strains. Sixteen other human strains inhibited the fourth group-A indicator (strain I7), and to a lesser extent strain I2, by lowering the pH of the typing medium. This acid-mediated inhibition was eliminated by testing on a medium containing calcium carbonate 0.5%; the 16 strains were then completely non-inhibitory, and the bacteriocin-forming strains, the typing pattern of which had originally been I2, I5, I7, I8, showed only inhibition attributable to the action of the bacteriocin. Nearly all group-A streptococci were sensitive to the group-G bacteriocin. The indicator strain I7 and several other members of M-type 28 were exceptions, but their resistance was not associated with the presence of R-antigen 28. Fifteen inhibitor-sensitivity patterns and 12 biotypes were identified among the strains; some of these tended to be associated with either a human or an animal origin. Neither S type nor biotype appeared to correlate with inhibitor production.

Animals↗
PubMed1983

M-type 57 group A streptococcus bacteriocin.

All 40 tested isolates of M-type 57 group A streptococci gave the same, highly characteristic inhibitory pattern (P-type 614) when tested by deferred antagonism using a set of nine indicator strains. One component of this inhibitory activity was attributed to the production of a bacteriocinlike substance, streptococcin A-M57 (SA-M57). Production of SA-M57 was enhanced by the presence of blood and also by growth at an alkaline pH. Partially purified SA-M57 was obtained from culture supernatants by a combination of ammonium sulphate fractionation and column chromatography. On Sephadex G-100 two different molecular weight forms (SA-M57 alpha, greater than 100 000; SA-M57 beta, 33 000) were demonstrated. Both SA-M57 forms were protease and heat sensitive and had identical inhibitory activity against a collection of indicator bacteria. The adsorption to and rate of kill of sensitive cells by SA-M57 was enhanced in the presence of human plasma. Partially purified SA-M57 preparations were devoid of M-type 57 protein and curing studies showed that loss of SA-M57 did not correlate with loss of M protein production.

Bacterial Proteins↗
PubMed1982

The production of bacteriocin-like substances by the oral bacterium Streptococcus salivarius.

Inhibitory substances produced by six strains of Streptococcus salivarius were isolated and partially characterized. The six prototype producer strains were selected initially on the basis of their differing spectra of inhibitory activity when tested against a set of nine standard indicator strains. Optimal production conditions were defined for each producer strain and inhibitor-containing extracts were obtained for characterization studies. All of the inhibitors appeared to be proteinaceous substances of molecular weight greater than 3500. When tested against a Streptococcus pyogenes indicator strain, one of the inhibitors was bactericidal, but the other five appeared to be bacteriostatic. Some differences between the inhibitors were observed with respect to heat and enzyme sensitivities.

Bacteriocins↗