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Biomedical subjects

J M Hardie

Publications and source records attributed to J M Hardie.

At least 19 recordsLinked to original sources
PubMed2002

Prevalence of helicobacter pylori at oral and gastrointestinal sites in children: evidence for possible oral-to-oral transmission.

Acquisition of Helicobacter pylori occurs mainly in childhood. However, the mode of transmission remains unclear. To help elucidate this, 100 children attending for upper gastrointestinal endoscopy were investigated for the presence of H. pylori at various sites. H. pylori was detected in antral gastric biopsies by the rapid urease test (13 patients), culture (13 patients), histology (15 patients) and PCR (20 patients). Gastric juice was positive for H. pylori in 3 patients by culture and 11 patients by PCR. The dental plaque from 68% of gastric biopsy-positive patients (as determined by culture or PCR) and 24% of gastric biopsy-negative patients was positive for H. pylori by PCR. The presence of H. pylori in dental plaque was significantly associated with the presence of this organism in the stomach. H. pylori was detected by PCR in the faeces of 25% of gastric biopsy-positive children sampled. H. pylori was not cultured on any occasion from the oral cavity or faeces. The evidence from this study suggests that oral-to-oral transmission may be a possible mode of spread of H. pylori in children.

Adolescent↗
PubMed2001

Morphological analysis of Helicobacter pylori from gastric biopsies and dental plaque by scanning electron microscopy.

Helicobacter pylori is rarely cultured from sites other than the gastric mucosa. The morphology of H. pylori in the stomach and dental plaque of adult dyspeptic patients was investigated to determine whether a difference in morphology at these sites could explain the inability to culture the organism from the oral cavity. Five adult patients attending for an upper gastrointestinal endoscopy were investigated. Dental plaque and gastric antral biopsy samples were analysed by culture and polymerase chain reaction (PCR) both before and after immunomagnetic separation using polyclonal rabbit anti-H. pylori IgG. Bead:bacteria aggregates were then examined by scanning electron microscopy (SEM). Rod and coccoid forms of H. pylori were seen by SEM in all oral and gastric samples which were H. pylori PCR positive. Although rod and coccoid forms have previously been shown to be associated with the gastric mucosa, this is the first time H. pylori cells have been visualized in dental plaque.

Adult↗
PubMed2001

Antimicrobial effect of acidified nitrite on periodontal bacteria.

The antimicrobial agent nitric oxide (NO) is formed in the mouth and its concentration is directly related to salivary nitrite, which in turn is related to dietary nitrate intake. The aim of this study was to determine whether nitrite under acidic conditions will have an inhibitory effect, possibly occurring through NO production, on the periodontal disease pathogens Fusobacterium nucleatum, Eikenella corrodens and Porphyromonas gingivalis. Whereas the growth of these organisms was inhibited by a more acid pH, the addition of nitrite caused a marked, further dose-dependent reduction in bacterial numbers after exposure. The ability of these bacteria to recover from nitrite exposure was also affected by pH and nitrite concentration. At acidity levels below pH 5.0, low concentrations of nitrite (0.2 mM) caused effective complete killing of the periodontal bacteria. Addition of sodium thiocyanate did not increase the bacteriostatic or bacteriocidal activity of acidified nitrite against any of the 3 bacteria. These results demonstrate the possibility that nitrite in saliva, under appropriate conditions, may have an effect on the growth and survival of the bacteria implicated in periodontal disease.

Acids↗
PubMed2000

Taxonomic study of "tufted mitior" strains of streptococci (Streptococcus sanguinis biotype 11); recognition of a new genospecies.

The taxonomic position of tufted strains of streptococci, phenotypically resembling Streptococcus mitis and previously referred to as 'tufted mitior' was investigated. By 16S rRNA sequence analysis, it was clear that the "tufted mitior" strains belonged to the mitis group of species within the genus Streptococcus. It was confirmed that these strains were taxonomically independent at the species level, sharing less than 43%, DNA-DNA similarity with all established species of the mitis group. However biochemical test data obtained, using three commercial identification kits (Rapid ID32 Strep, STREPTOGRAM, and Biolog GP-plate) together with in-house biochemical tests employing 4-MUF-linked fluorogenic substrates did not reveal sufficient differential tests with which to identify the "tufted mitior" strains unequivocally. From these data, we conclude that these "tufted mitior" strains represent a new taxon within the mitis group of the genus Streptococcus, and propose that they should be considered as a genospecies until differential phenotypic characteristics are found for their identification.

Bacterial Typing Techniques↗
PubMed2000

Quantitative culture of Helicobacter pylori from gastric juice: the potential for transmission.

The transmission of Helicobacter pylori may occur by spread of organisms from gastric juice which has been introduced into the mouth by gastro-oesophageal reflux. The aim of this study was to quantify the load of H. pylori present in gastric juice available for transmission. Gastric antral biopsy and gastric juice samples were collected from 108 adult dyspeptic patients undergoing routine upper gastroscopy and the presence of H. pylori was determined. In all, 54 (50%) of 108 patients gave positive results in the gastric antral biopsy rapid urease test and for H. pylori histology. The gastric juice of 40 (37%) of patients gave positive results for the urease A gene by PCR assay; 34 (31%) of patients were positive by these three tests and H. pylori was cultured from the gastric juice of 13 (38%) of these patients. The median count of H. pylori in gastric juice was 1.75 x 10(1) cfu/ml. Viable organisms in gastric juice may lead to transmission of H. pylori when refluxed or vomited into the mouth.

Adolescent↗
PubMed2000

Distribution of the intermedilysin gene among the anginosus group streptococci and correlation between intermedilysin production and deep-seated infection with Streptococcus intermedius.

The distribution of intermedilysin, a human-specific cytolysin, among the anginosus group streptococci and the correlation of toxin production and infection by Streptococcus intermedius were investigated. PCR and Southern hybridization specific for the intermedilysin gene revealed that the toxin gene exists only in S. intermedius and no homologue to the toxin gene is distributed in S. anginosus and S. constellatus. Thus, the intermedilysin gene is useful as a marker gene of S. intermedius. Moreover, a human-specific hemolysis assay and Western blotting with intermedilysin-specific antibodies clearly demonstrated that the intermedilysin production level in isolates from deep-seated infections, such as brain and liver abscesses, is higher (6.2- to 10.2-fold, respectively) than in strains from normal habitats, such as dental plaque, or from peripheral infection sites. However, other candidate virulence factors of S. intermedius, such as chondroitin sulfate depolymerase, hyaluronidase, and sialidase activities, did not show such a clear correlation between enzymatic activity and isolation sites or disease severity. From these results, intermedilysin is likely to be the pathogenic or triggering factor of significance in inducing deep-seated infections with S. intermedius.

Gene Expression↗
PubMed1999

Antimicrobial effect of acidified nitrite on cariogenic bacteria.

The antimicrobial agent nitric oxide (NO) is formed in the mouth and its concentration is directly related to salivary nitrite, which in turn is related to dietary nitrate intake. The aim of this study was to determine whether nitrite under acidic conditions will have an inhibitory effect, possibly occurring through NO production, on Streptococcus mutans, Lactobacillus casei and Actinomyces naeslundii. Whereas the growth of S. mutans was inhibited by a more acid pH, the addition of nitrite caused a marked, further dose-dependent reduction in bacterial numbers after 24 h of exposure. Similar effects were observed with A. naeslundii and L. casei. The ability of these bacteria to recover from nitrite exposure was also markedly affected by nitrite concentration. At acidity levels below pH 7, low concentrations of nitrite (0.2 mM) caused effective complete killing of S. mutans, with similar effects on the other organisms tested. These results demonstrate the possibility that nitrite in saliva has an effect on the growth and survival of cariogenic bacteria.

Actinomyces↗
PubMed1999

A study of small-colony, beta-haemolytic, Lancefield group C streptococci within the anginosus group: description of Streptococcus constellatus subsp. pharyngis subsp. nov., associated with the human throat and pharyngitis.

beta-Haemolytic, Lancefield group C streptococci within the anginosus-species group were shown by genetic and phenotypic criteria to be heterogeneous and to constitute two distinct taxa related at subspecies level to Streptococcus constellatus and Streptococcus anginosus, respectively. The first group, referred to here as DNA group 1, comprised six strains with 86-100% intragroup overall genomic DNA relatedness; five of the strains were originally isolated from the human throat and one was from an abdominal mass. They shared 61-77% DNA relatedness (delta Tm values = 1.2-1.5 degrees C) with reference strains of S. constellatus and were clearly differentiated from S. constellatus (now named Streptococcus constellatus subsp. constellatus) by the ability to produce beta-N-acetylgalactosaminidase, beta-N-acetylglucosaminidase, beta-D-fucosidase, beta-D-galactosidase and beta-D-glucosidase. The name S. constellatus subsp. pharyngis is proposed for these strains on the grounds that they are genetically and phenotypically distinct and exhibit a predeliction for the human throat, being isolated also from cases of pharyngitis. The DNA G + C content is 35-37 mol%. The type strain is MM9889aT (= NCTC 13122T). The second group (DNA group 2) was formed by five beta-haemolytic, Lancefield group C strains originally isolated from various human infections. DNA group 2 strains (81-100% intragroup DNA relatedness) shared 60-72% DNA relatedness (delta Tm values = 2.1-4.1 degrees C) with S. anginosus strains NCTC 10713T and MAS 283 but were not clearly differentiated phenotypically from S. anginosus, showed no clear pattern of clinical association, and therefore are not formally proposed as a new subspecies here.

Bacterial Typing Techniques↗
PubMed1999

Comparison of the effects of anaerobic and micro-aerophilic incubation on resistance of Helicobacter pylori to metronidazole.

To assess the influence of incubation conditions on the resistance of Helicobacter pylori this study compared the effect of micro-aerophilic and anaerobic incubation followed by micro-aerophilic incubation on the measurement of metronidazole resistance of 102 H. pylori isolates, by both disk diffusion and Epsilometer (E)-tests. Anaerobic incubation for 24 h before micro-aerophilic incubation for 48 h consistently increased metronidazole activity in both assay methods. Although statistically significant, this was microbiologically less significant, as only 4 of 102 isolates gave discrepant readings (all four were resistant in micro-aerophilic conditions but susceptible in anaerobic/micro-aerophilic conditions). In all four cases variation was by a few millimeters in zone size (i.e., all were close to the cut-off point). There was 100% agreement between disk diffusion and E-test results. Of 104 observations (52 duplicate assays: 13 strains, two atmospheric conditions, two methods of determining resistance) there was 100% intra-observer and inter-observer agreement with regard to susceptibility and resistance status for both E-test and disk diffusion methods. Anaerobic incubation followed by micro-aerophilic incubation had little effect on the estimation of prevalence of metronidazole resistance and seemed to add little, if any, significant advantage over micro-aerophilic incubation alone.

Aerobiosis↗
PubMed1997

Prevalence of Porphyromonas and Prevotella species in the dental plaque of dogs.

The prevalence and populations of Porphyromonas and Prevotella species were determined in three samples of dental plaque from each of 34 healthy dogs. Porphyromonas gingivalis was present in 68 per cent of the dogs and 47 per cent of the plaque samples. The counts of P gingivalis increased with age (P < 0.1), the amount of plaque (P < 0.05) and the degree of gingivitis (P < 0.1). Prevotella intermedia was present in 44 per cent of the dogs and 23 per cent of the plaque samples. The counts of P intermedia were correlated with the amount of plaque (P < 0.05) and the degree of gingivitis (P < 0.1). Porphyromonas canoris, P salivosa, P cangingivalis, P cansulci, P crevioricanis and Prevotella denticola were isolated from only 9, 6, 3, 3, 3 and 3 per cent of the dogs, respectively. Porphyromonas gingivicanis was not isolated from any of the animals sampled. There was a highly significant (P < 0.001) correlation between the amount of plaque, the extent of gingivitis and the age of the dog.

Animals↗
PubMed1997

Dental plaque flora of the dog with reference to fastidious and anaerobic bacteria associated with bites.

Animal bite wounds are amongst the most common types of traumatic injuries in humans. The organisms isolated from these wounds generally reflect the oral flora of the biting animal, and may be fastidious in nature and difficult to identify. This study was undertaken to determine the prevalence of Eikenella corrodens, Actinobacillus actinomycetemcomitans, Porphyromonas and Prevotella spp. in supragingival dental plaque collected from the right maxillary canine and carnassial teeth and the right mandibular canine tooth of dogs. In part one of the study, 30 dogs were used. E. corrodens was found in 62% of these dogs and 44% of individual plaque samples. A. actinomycetemcomitans was not detected in any of the dogs sampled. In part two, 34 dogs were used to determine the prevalence of the black pigmented anaerobic bacilli (Porphyromonas and Prevotella spp.). Porphyromonas gingivalis was present in 68% of these dogs and 47% of individual plaque samples. Prevotella intermedia was present in 44% of the dogs and 23% of individual plaque samples. The recently described Porphyromonas canoris, Porphyromonas salivosa, Porphyromonas cangingivalis, Porphyromonas cansulci, Porphyromonas crevioricanis and Prevotella denticola species were isolated from only 9%, 6%, 3%, 3%, 3% and 3% of dogs respectively. Porphyromonas gingivicanis was not isolated from any of the animals sampled. In conclusion, black-pigmented anaerobic bacilli were isolated from 91% of the animals sampled and therefore constitute a significant risk with respect to bite wound infections. It is also suggested that the prevalence of E. corrodens in wound infections has been underestimated in previous reports because of use of inappropriate techniques for detecting this organism.

Aggregatibacter actinomycetemcomitans↗
PubMed1996

Interactions between Eikenella corrodens and 'Streptococcus milleri-group' organisms: possible mechanisms of pathogenicity in mixed infections.

Interactions between the 'Streptococcus milleri-group' organisms (SMG; S. intermedius, S. constellatus and S. anginosus) and Eikenella corrodens were investigated. Coaggregation reactions occurred frequently between S. anginosus (83% of strain combinations) or S. constellatus (87%) and E. corrodens isolates, but were infrequent between S. intermedius and E. corrodens (28%). No enhancement of enzyme activities against lipid, phosphate, peptide and saccharide substrates tested were detected with combinations of species in comparison to the species alone. Exponential growth of S. constellatus and S. intermedius, in mixed culture with E. corrodens, occurred within 6h post inoculation, in comparison to 25h without E. corrodens. No growth stimulation of S. anginosus was observed. It is concluded that both coaggregation and growth stimulation occur between E. corrodens and SMG isolates, and may be important mechanisms in the establishment of mixed infections involving these bacteria.

Bacterial Adhesion↗
PubMed1995

Migration and Helicobacter pylori seroprevalence: Bangladeshi migrants in the U.K.

Helicobacter pylori, an infectious agent of worldwide public health importance, has higher seroprevalence in developing countries than in developed countries. We investigated whether Bangladeshi women, born in Bangladesh, have a greater H. pylori seroprevalence than Bangladeshi women born in the U.K. and, in addition, whether there is an association between H. pylori seropositivity and age of migration to the U.K. amongst Bangladeshi women. Women attending antenatal clinics at the Royal London Hospital were screened using ELISA for anti-H. pylori IgG. In Bangladeshi individuals born in the U.K., 13/16 (81%, 95% confidence interval (CI) 54%-96%) and, in Bangladeshi individuals born in Bangladesh 91/137 (66%, 95% CI 59%-74%) had antibodies to H. pylori. No significant association was found between H. pylori seropositivity and country of birth, or age at migration to the U.K. Public health strategies concerning H. pylori should consider migrant populations with high seroprevalence of H. pylori.

Adolescent↗