Biomedical subjects

J R Tagg

Publications and source records attributed to J R Tagg.

At least 19 recordsLinked to original sources

PubMed2006

A preliminary study of the effect of probiotic Streptococcus salivarius K12 on oral malodour parameters.

AIMS: To determine whether dosing with bacteriocin-producing Streptococcus salivarius following an antimicrobial mouthwash effects a change in oral malodour parameters and in the composition of the oral microbiota of subjects with halitosis. MATERIALS AND RESULTS: Twenty-three subjects with halitosis undertook a 3-day regimen of chlorhexidine (CHX) mouth rinsing, followed at intervals by the use of lozenges containing either S. salivarius K12 or placebo. Assessment of the subjects' volatile sulphur compound (VSC) levels 1 week after treatment initiation showed that 85% of the K12-treated group and 30% of the placebo group had substantial (>100 ppb) reductions. The bacterial composition of the saliva was monitored by culture and PCR-denaturing gradient gel electrophoresis (PCR-DGGE). Changes in the PCR-DGGE profiles occurred in most subjects following K12 treatment. In vitro testing showed that S. salivarius K12 suppressed the growth of black-pigmented bacteria in saliva samples and also in various reference strains of bacteria implicated in halitosis. CONCLUSIONS: Administration of bacteriocin-producing S. salivarius after an oral antimicrobial mouthwash reduces oral VSC levels. SIGNIFICANCE AND IMPACT OF THE STUDY: The outcome of this preliminary study indicates that the replacement of bacteria implicated in halitosis by colonization with competitive bacteria such as S. salivarius K12 may provide an effective strategy to reduce the severity of halitosis.

Administration, Oral↗

PubMed2006

Commensal bacilli inhibitory to mastitis pathogens isolated from the udder microbiota of healthy cows.

AIMS: To isolate from the microbiota of the healthy cow udder commensal bacteria having antimicrobial activity against bovine mastitis pathogens, with a long-term view to their potential application as antimastitis probiotics. METHODS AND RESULTS: Bacterial isolates from four healthy cow udders were tested for inhibitory activity against three Gram-positive indicator bacteria. This led to the selection of nine broadly inhibitory strains. All were of the Bacillus genus and their antimicrobial activities, which appeared heterogeneous on the basis of their antibacterial spectra and heat susceptibilities, enabled grouping of the inhibitory bacilli into six different inhibitory profiles. All displayed strong in vitro activity against Gram-positive mastitis pathogens. Inhibitory bacilli were recovered from each of the 11 udder samples collected over 7 months from one of these cows and the isolates included representatives of all six inhibitory profiles. CONCLUSIONS: Bacilli present in the udder microbiota of healthy cows can produce a variety of broadly active inhibitors of Gram-positive bacteria, including potential mastitis pathogens. SIGNIFICANCE AND IMPACT OF THE STUDY: Inhibitor-producing strains of commensal Bacillus species have been identified, which may have the potential for use as possible antimastitis probiotics.

Animals↗

PubMed2005

The rationale and potential for the reduction of oral malodour using Streptococcus salivarius probiotics.

The primary treatment for oral malodour is the reduction of bacterial populations, especially those present on the tongue, by use of a variety of antimicrobial agents or mechanical devices. However, shortly after treatment the problematic bacteria quickly repopulate the tongue and the malodour returns. In our studies, we have used a broadly-active antimicrobial (chlorhexidine) to effect temporary depletion of the oral microbiota and then have attempted to repopulate the tongue surface with Streptococcus salivarius K12, a benign commensal probiotic. The objective of this is to prevent re-establishment of non-desirable bacterial populations and thus help limit the re-occurrence of oral malodour over a prolonged period. In this paper, we discuss why contemporary probiotics are inadequate for treatment of oral malodour and examine the rationale for selection of particular bacterial species for future use in the treatment of this condition. In our preliminary trials of the use of a chlorhexidine rinse followed by strain K12 lozenges, the majority (8/13) of subjects with confirmed halitosis maintained reduced breath levels of volatile sulphur compounds for at least 2 weeks. We conclude that probiotic bacterial strains originally sourced from the indigenous oral microbiotas of healthy humans may have potential application as adjuncts for the prevention and treatment of halitosis.

Halitosis↗

PubMed2004

Prevention of streptococcal pharyngitis by anti-Streptococcus pyogenes bacteriocin-like inhibitory substances (BLIS) produced by Streptococcus salivarius.

BACKGROUND & OBJECTIVES: Streptococcus salivarius is a numerically prominent member of the human oral microbiota that produces a variety of bacteriocin-like inhibitory substances (BLIS) having in vitro inhibitory activity against S. pyogenes. Our previous studies of S. salivarius isolates from children using a deferred antagonism BLIS production (P)-typing scheme showed that the 9 per cent of children having large populations of P-type 677 S. salivarius experienced fewer S. pyogenes acquisitions than either the 11 per cent of children having predominant P-type 226 populations or the 60 per cent of children with largely non-inhibitory (P-type 000) S. salivarius. Amongst the other BLIS P-types detected were a number of strongly-inhibitory (P-type 777) S. salivarius. In the present study the inhibitory agents produced by prototype strains of P-types 226, 677 and 777 S. salivarius are compared. METHODS: The prototype BLIS-producing S. salivarius strains SN, 20P3, and K12 were isolated from tongue swabbings. BLIS P-typing was done using standard procedures. The BLIS molecules were purified and characterized. RESULTS: S. salivarius SN (P-type 226) produces a heat-labile muramidase. S. salivarius 20P3 (P-type 677) produces the 2315 Da lantibiotic salivaricin A and S. salivarius K12 (P-type 777) produces two lantibiotics; salivaricin A2 (2368 Da) and salivaricin B (2733 Da). INTERPRETATION & CONCLUSION: The P-type 777 S. salivarius strain produced salivaricin A2 and salivaricin B. The combined production of two anti-S. pyogenes BLIS activities by this strain indicates that it could be adopted as a colonizing strain in bacterial interference trials.

Amino Acid Sequence↗

PubMed2004

Genetic basis for mutacin N and of its relationship to mutacin I.

BACKGROUND & OBJECTIVES: The mutans streptococci (MS) are a group of 7 species of dental cariesassociated bacteria of which Streptococcus mutans and Streptococcus sobrinus are the most important in humans. Many MS produce bacteriocin-like inhibitory substances (BLIS), some of which have been characterised as small peptides capable of inhibiting the growth of closely-related species. These peptides have most commonly been referred to as mutacins. S. mutans strains N and UA140 appear to have closely similar BLIS activities. Both produce mutacins that seem to target the same species of bacteria. On closer analysis however, these two strains have been shown to produce distinctly different mutacins, known as mutacin N and mutacin I respectively. In the present study the mutacin N structural gene (mutN) was cloned and compared with the mutacin I structural gene (mutA). METHODS: Cloning and sequencing of S. mutans N was done. The distribution of mutN using DNA from 216 streptococcal strains was determined by dot blotting. RESULTS: Mut N was cloned and sequenced from an 1800 bp Bam HI/Eco RI fragment. PCR with the mutN primers mutNF and mutNR on the four mutN-positive strains identified identical bands to S. mutans N. The location of mutN differs significantly from that of mutA in that it is directly upstream of comC, a gene encoding a putative competence stimulating factor. INTERPRETATION & CONCLUSION: The close upstream proximity of mutN to comC suggests a link between mutacin N production and competence development. Further studies need to be done to detect competence-related genes in S. mutans strain N.

Bacteriocins↗

PubMed2002

Different bacteriocin activities of Streptococcus mutans reflect distinct phylogenetic lineages.

Bacteriocins produced by mutans streptococci are known as mutacins. In this study 16 broadly active mutacin-producing Streptococcus mutans strains from New Zealand, North America and Europe were classified into four groups (A-D) on the basis of differences in their activity in deferred antagonism tests against either the homologous producer strain (to test for presence of self-immunity) or indicator strains Staphylococcus aureus 46 and Enterococcus faecium TE1. Two of the strains included in the study (UA140 and UA96) were representatives of the group I and II mutacin producer strains previously described by Caufield and co-workers. One of the New Zealand isolates of group A (S. mutans strain N) appeared to produce inhibitory activity similar to that of the group I prototype strain UA140. Four other New Zealand isolates of group B (S. mutans strains M19, M34, B34 and D14) had mutacin II-like activity. The group B mutacin producers differed from the group A mutacin producers in their additional activity against Staph. aureus 46. Seven S. mutans strains (M46, B46, B57, M12, M28, B28 and 13M) were distinguished from the group A and group B mutacin producers in that they inhibited E. faecium TE1. These were called group C mutacin producers. Strains H7 and H23 resembled the group C strains in their action on both indicator strains TE1 and 46. However, these two strains failed to exhibit immunity to their own inhibitory products in the deferred antagonism test and were separately classified as group D mutacin producers. Phylogenetic analysis of the strains by several genotypic and phenotypic characteristics revealed that the mutacin groups were associated with distinct evolutionary lineages of S. mutans.

Adult↗

PubMed2001

Intra- and interspecies signaling between Streptococcus salivarius and Streptococcus pyogenes mediated by SalA and SalA1 lantibiotic peptides.

Streptococcus salivarius 20P3 produces a 22-amino-acid residue lantibiotic, designated salivaricin A (SalA), that inhibits the growth of a range of streptococci, including all strains of Streptococcus pyogenes. Lantibiotic production is associated with the sal genetic locus comprising salA, the lantibiotic structural gene; salBCTX genes encoding peptide modification and export machinery proteins; and salYKR genes encoding a putative immunity protein and two-component sensor-regulator system. Insertional inactivation of salB in S. salivarius 20P3 resulted in abrogation of SalA peptide production, of immunity to SalA, and of salA transcription. Addition of exogenous SalA peptide to salB mutant cultures induced dose-dependent expression of salA mRNA (0.2 kb), demonstrating that SalA production was normally autoregulated. Inactivation of salR encoding the response regulator of the SalKR two-component system led to reduced production of, and immunity to, SalA. The sal genetic locus was also present in S. pyogenes SF370 (M type 1), but because of a deletion across the salBCT genes, the corresponding lantibiotic peptide, designated SalA1, was not produced. However, in S. pyogenes T11 (M type 4) the sal locus gene complement was apparently complete, and active SalA1 peptide was synthesized. Exogenously added SalA1 peptide from S. pyogenes T11 induced salA1 transcription in S. pyogenes SF370 and in an isogenic S. pyogenes T11 salB mutant and salA transcription in S. salivarius 20P3 salB. Thus, SalA and SalA1 are examples of streptococcal lantibiotics whose production is autoregulated. These peptides act as intra- and interspecies signaling molecules, modulating lantibiotic production and possibly influencing streptococcal population ecology in the oral cavity.

Amino Acid Sequence↗

PubMed2000

High pharyngeal carriage rates of Streptococcus pyogenes in Dunedin school children with a low incidence of rheumatic fever.

AIM: To document the incidence and type distribution of Streptococcus pyogenes in a group of Dunedin children throughout the 1997 school year. METHODS: The 780 children recruited from ten primary schools had their throats swabbed on each reporting of pharyngitis. Additional pharyngeal swabbings were obtained monthly from a representative subset of these children, referred to as group 1. All swab samples were plated on CNA-P, a blood agar medium that facilitates detection of haemolytic streptococci. S. pyogenes isolates were classified according to the RFLP patterns of PCR products of their emm genes (ERP typing). Representative isolates of each ERP pattern were also emm-typed, a sequence typing method that correlates with serological M-typing. RESULTS: 28% of the group 1 children were found to carry S. pyogenes for more than two months. This carriage rate is similar to that previously detected in Dunedin and Waikato schoolchildren, but is higher than that generally reported in other countries. Although the predominant S. pyogenes types detected in Dunedin are similar to those in North Island populations, some of the types frequently associated with North Island cases of rheumatic fever and glomerulonephritis were absent or isolated infrequently from the Dunedin children. CONCLUSION: The high pharyngeal carriage rates of S. pyogenes in Dunedin schoolchildren, without the concomitant increased occurrence of post-streptococcal sequelae observed in North Island populations may, in part, be due to a relatively lower occurrence of the M-types most commonly implicated in these diseases.

Bacterial Typing Techniques↗

PubMed2000

Streptococcus mutans strain N produces a novel low molecular mass non-lantibiotic bacteriocin.

Streptococcus mutans strain N was shown to have bacteriocin production and immunity characteristics consistent with those of Group I mutacin-producing strains of S. mutans. The bacteriocin mutacin N was purified from agar cultures of S. mutans strain N using XAD andp6 reversed phase chromatography. The molecular mass of mutacin N was 4806 Da and the entire 49 amino acid sequence was determined by N-terminal sequencing. Database searches indicate that mutacin N is a novel bacteriocin, but with some homology to the protein IIC domain of a hypothetical sugar-phosphotransferase enzyme from Acholeplasma florum.

Amino Acid Sequence↗

PubMed2000

Dental caries is a preventable infectious disease.

Dental caries is the most common infectious disease affecting humans. The principal causative agents are a group of streptococcal species collectively referred to as the mutans streptococci of which Streptococcus mutans and Streptococcus sobrinus are the most important agents of human caries. This review outlines what is currently known about these ubiquitous pathogens and discusses novel methods for elimination of these bacteria from dental plaque.

Adult↗

PubMed2000

A new alkaline pH-adjusted medium enhances detection of beta-hemolytic streptococci by minimizing bacterial interference due to Streptococcus salivarius.

A new selective medium (CNA-P) that reduces or eliminates the inhibitory activity of bacteriocin-producing Streptococcus salivarius against beta-hemolytic streptococci has been developed and compared with sheep blood agar (SBA) for the sensitive detection of small numbers of beta-hemolytic streptococci in clinical specimens. CNA-P has as its basis a commercial medium (Difco Columbia CNA agar) supplemented with 5% (vol/vol) sheep blood, and the CNA is further modified by addition of 100 mM PIPES buffer [piperazine-N,N'-bis(2-ethanesulfonic acid)] (pH 7.5) to maintain cultures at an alkaline pH during incubation. CNA-P was shown to inhibit the production and/or release of four different types of S. salivarius bacteriocins or bacteriocin-like inhibitory molecules. The efficacies of CNA-P and SBA for detection of beta-hemolytic streptococci in 1,352 pharyngeal samples from 376 children were compared. The beta-hemolytic streptococcal isolates recovered from the samples included 314 group A (S. pyogenes), 61 group G, 33 group B, and 5 group C streptococci. Of 314 samples that yielded S. pyogenes, 300 were positive on CNA-P (96%) and 264 (86%) were positive on SBA. A significantly greater number of S. pyogenes isolates from these samples were recovered only on CNA-P (50 of 314) compared with the number of isolates recovered only on SBA (14 of 314). In addition, the degree of positivity, a measure of the total numbers of S. pyogenes isolates on the plate, was significantly higher on CNA-P than on SBA (2.40 versus 2.07; P < 0.001). Interestingly, CNA-P was also found to enhance the hemolytic activity of streptolysin O, allowing detection of streptolysin S-deficient S. pyogenes strains which might otherwise go undetected on SBA and other isolation media.

Agar↗

PubMed1999

Identification of genes encoding two-component lantibiotic production in Staphylococcus aureus C55 and other phage group II S. aureus strains and demonstration of an association with the exfoliative toxin B gene.

The production of exfoliative toxin B (ET-B), but not ET-A, was shown to be specifically associated with production of a highly conserved two-component lantibiotic peptide system in phage group II Staphylococcus aureus. Two previously studied but incompletely characterized S. aureus bacteriocins, staphylococcins C55 and BacR1, were found to be members of this lantibiotic system, and considerable homology was also found with the two-component Lactococcus lactis bacteriocin, lacticin 3147. sacalphaA and sacbetaA, the structural genes of the lantibiotics staphylococcins C55alpha and C55beta and two putative lantibiotic processing genes, sacM1 and sacT, were localized together with the ET-B structural gene to a single 32-kb plasmid in strain C55. Irreversible loss of both ET-B and two-component lantibiotic production occurs during laboratory passage of ET-B-positive S. aureus strains, particularly at elevated temperatures.

Amino Acid Sequence↗

PubMed1998

Two-component anti-Staphylococcus aureus lantibiotic activity produced by Staphylococcus aureus C55.

Staphylococcus aureus C55 was shown to produce bacteriocin activity comprising three distinct peptide components, termed staphylococcins C55alpha, C55beta, and C55gamma. The three peptides were purified to homogeneity by a simple four-step purification procedure that consisted of ammonium sulfate precipitation followed by XAD-2 and reversed-phase (C8 and C18) chromatography. The yield following C8 chromatography was about 86%, with a more-than-300-fold increase in specific activity. When combined in approximately equimolar amounts, staphylococcins C55alpha and C55beta acted synergistically to kill S. aureus or Micrococcus luteus but not S. epidermidis strains. The N-terminal amino acid sequences of all three peptides were obtained and staphylococcins C55alpha and C55beta were shown to be lanthionine-containing (lantibiotic) molecules with molecular weights of 3,339 and 2,993, respectively. The C55gamma peptide did not appear to be a lantibiotic, nor did it augment the inhibitory activities of staphylococcin C55alpha and/or C55beta. Plasmids of 2. 5 and 32.0 kb are present in strain C55, and following growth of this strain at elevated temperature (42 degreesC), a large proportion of the progeny failed to produce strong bacteriocin activity and also lost the 32.0-kb plasmid. Protoplast transformation of these bacteria with purified 32-kb plasmid DNA regenerates the ability to produce the strong bacteriocin activity.

Amino Acids↗

PubMed1997

Cloning and sequence analysis of zooA, a Streptococcus zooepidemicus gene encoding a bacteriocin-like inhibitory substance having a domain structure similar to that of lysostaphin.

The nucleotide sequence has been determined for zooA, a gene encoding the bacteriocin-like inhibitory substance zoocin A in Streptococcus zooepidemicus strain 4881. The zooA gene product corresponds to the 285-amino acid (aa) zoocin A pre-peptide from which a leader sequence is cleaved to form the 262-aa biologically active molecule of estimated molecular mass 27,877 Da. Expression of zooA in a Gram-negative host was shown by the extracellular release from Escherichia coli, containing cloned zooA, of a biologically active peptide having an identical range of anti-bacterial activity to that of zoocin A, purified from S. zooepidemicus strain 4881. Data base searches revealed sequences having homologies with known muralytic proteins produced by both Gram-positive and Gram-negative bacteria and indicate a 'mix and match' blending of domain-type structures, the C-terminal putative receptor-recognition region of the molecule being joined by a threonine-proline-rich linker to an N-terminal putative catalytic region having homology with several known endopeptidases, including lysostaphin.

Amino Acid Sequence↗

PubMed1997

Bacteriocin production and sensitivity among coaggregating and noncoaggregating oral streptococci.

Twenty-one oral Streptococcus isolates of known interbacterial coaggregation groups were tested against one another (as both producers and indicators) to detect bacteriocin-like inhibitory activity. In agar-based antagonism tests, seven strains produced small inhibitory zones (< or = 3 mm diameter) but in liquid medium, only strain Streptococcus gordonii DL1 (Challis) produced a detectable antibacterial action (bacteriocin STH1). Five strains were sensitive to bacteriocin STH1, but neither the production of nor the sensitivity to any of the antagonistic agents correlated with coaggregation groupings. Four strains (C219, 903, 118 and Wicky) developed stable resistance in response to the bacteriocin, whereas one isolate (strain 34) remained sensitive following repeated bacteriocin exposure. With one exception (strain 903), bacteriocin STH1-sensitive strains were competent for genetic transformation, but not all competent strains were bacteriocin-sensitive. Bacteriocin-resistant derivatives of transformable strains exhibited decreased competence (80-90% reduction) compared with their parent strains.

Actinomyces↗

PubMed1996

Novel lantibiotics and their pre-peptides.

In recent years there has been a considerable increase in studies of bactericidal peptides produced by Gram-positive bacteria, with particular emphasis upon their potential application as food preservatives. A number of these peptides contain lanthionine and other post-translationally modified amino acid residues. The lanthionine-containing molecules (lantibiotic) appear to have evolved in two quite different lineages, type A and type B. This mini-review introduces the reader to several of the more recently described type A lantibiotics for which relatively detailed biochemical and/or genetic data has already been gathered. A wider diversity of compounds of type A lantibiotics has been described in the recent years. Novel features of some of the more recently described type A lantibiotics to be reported in this review include: a) New modifications such as D-Ala and 2-hydroxypropionyl residues, both derived from serine. b) Different types of pre-lantibiotic leader sequences. c) The apparent requirement for different numbers and types of genes for synthesis of some active type A lantibiotics. d) Cytolysin functions as both a hemolysin and a bacteriocin. e) One of the newly-described lantibiotics (lactocin S) does not have any net charge at neutral pH another (carnocin UI49) is the largest of the lantibiotics discovered and the killing action of another (cytolysin) has been shown to be depend on the interaction of two peptides.

Alanine↗

PubMed1996

Mode of action of a lysostaphin-like bacteriolytic agent produced by Streptococcus zooepidemicus 4881.

Electron microscopy of zoocin A-treated sensitive streptococcus cells revealed cytoplasmic disruption and ultimately complete rupture of the cell wall. Culture viability and optical density were shown to decrease rapidly and simultaneously in Streptococcus pyogenes FF22 but less quickly in the relatively more resistant Streptococcus mutans 10449. Zoocin A was shown to cleave hexaglycine in a colorimetric cell-free microtiter assay system, and it is concluded that the killing action of zoocin A, like that of lysostaphin, is most probably the result of direct cleavage of the peptidoglycan cross-links in the cell wall. The relationship between sensitivity to zoocin A and the peptidoglycan cross-linkage structure of Streptococcus zooepidemicus, Lactococcus spp., S. pyogenes, Streptococcus gordonii, Streptococcus oralis, S. mutans, and Streptococcus rattus has been evaluated.

Anti-Bacterial Agents↗

PubMed1995

Bacteriocins of gram-positive bacteria.

In recent years, a group of antibacterial proteins produced by gram-positive bacteria have attracted great interest in their potential use as food preservatives and as antibacterial agents to combat certain infections due to gram-positive pathogenic bacteria. They are ribosomally synthesized peptides of 30 to less than 60 amino acids, with a narrow to wide antibacterial spectrum against gram-positive bacteria; the antibacterial property is heat stable, and a producer strain displays a degree of specific self-protection against its own antibacterial peptide. In many respects, these proteins are quite different from the colicins and other bacteriocins produced by gram-negative bacteria, yet customarily they also are grouped as bacteriocins. Although a large number of these bacteriocins (or bacteriocin-like inhibitory substances) have been reported, only a few have been studied in detail for their mode of action, amino acid sequence, genetic characteristics, and biosynthesis mechanisms. Nevertheless, in general, they appear to be translated as inactive prepeptides containing an N-terminal leader sequence and a C-terminal propeptide component. During posttranslational modifications, the leader peptide is removed. In addition, depending on the particular type, some amino acids in the propeptide components may undergo either dehydration and thioether ring formation to produce lanthionine and beta-methyl lanthionine (as in lantibiotics) or thio ester ring formation to form cystine (as in thiolbiotics). Some of these steps, as well as the translocation of the molecules through the cytoplasmic membrane and producer self-protection against the homologous bacteriocin, are mediated through specific proteins (enzymes). Limited genetic studies have shown that the structural gene for such a bacteriocin and the genes encoding proteins associated with immunity, translocation, and processing are present in a cluster in either a plasmid, the chromosome, or a transposon. Following posttranslational modification and depending on the pH, the molecules may either be released into the environment or remain bound to the cell wall. The antibacterial action against a sensitive cell of a gram-positive strain is produced principally by destabilization of membrane functions. Under certain conditions, gram-negative bacterial cells can also be sensitive to some of these molecules. By application of site-specific mutagenesis, bacteriocin variants which may differ in their antimicrobial spectrum and physicochemical characteristics can be produced. Research activity in this field has grown remarkably but sometimes with an undisciplined regard for conformity in the definition, naming, and categorization of these molecules and their genetic effectors. Some suggestions for improved standardization of nomenclature are offered.

Amino Acid Sequence↗