The significance of cagA and vacA subtypes of Helicobacter pylori in the pathogenesis of inflammation and peptic ulceration.
AIMS: To assess the significance of cagA and vacA subtypes of Helicobacter pylori in relation to inflammation and density of bacterial colonisation in vivo within a dyspeptic UK population. METHODS: Dyspeptic patients who were Helicobacter pylori positive had antral samples taken for histology and culture. Gastroduodenal pathology was noted. The grade of bacterial density and inflammation was assessed using the Sydney system. Bacterial DNA was extracted and the vacA alleles and the cagA/gene typed using PCR. RESULTS: 120 patients were studied. There was high rate of cagA positive strains in this population. Bacterial density did not correlate with the presence of peptic ulceration. There was a significant association between cagA positive strains and increased inflammation and bacterial density. The vacA s1 type independently correlated with extensive chronic inflammation but there was no association with bacterial density. The vacA m type did not correlate with extent of inflammation or bacterial density. CONCLUSIONS: The results suggest that cagA is important in the pathogenesis of inflammation and peptic ulceration. These findings are in keeping with the hypothesis that cagA acts as a marker for a cag pathogenicity island which encodes several genes involved in inflammation. The vacA s1 allele correlates with inflammation independently of cagA, possibly through its enhanced ability to produce the vacuolating cytotoxin. (+info)
Acinetobacter bacteremia in Hong Kong: prospective study and review.
The epidemiological characteristics of 18 patients with acinetobacter bacteremia were analyzed. Patients (mean age, 55.5 years) developed bacteremia after an average of 14.1 days of hospitalization. Fifteen of 16 patients survived bacteremia caused by Acinetobacter baumannii. Cultures of blood from the remaining two patients yielded Acinetobacter lwoffii. Most patients (78%) resided in the general ward, while four patients (22%) were under intensive care. Genotyping by arbitrarily primed polymerase chain reaction analysis and the temporal sequence of isolation were more useful than phenotyping by antimicrobial susceptibility in the determination of the source of bacteremia, and the intravascular catheter was the leading infection source (39% of cases). The possibility of an association of glucose with the pathogenesis of acinetobacter infection was raised. (+info)
Legionnaires' disease on a cruise ship linked to the water supply system: clinical and public health implications.
The occurrence of legionnaires' disease has been described previously in passengers of cruise ships, but determination of the source has been rare. A 67-year-old, male cigarette smoker with heart disease contracted legionnaires' disease during a cruise in September 1995 and died 9 days after disembarking. Legionella pneumophila serogroup 1 was isolated from the patient's sputum and the ship's water supply. Samples from the air-conditioning system were negative. L. pneumophila serogroup 1 isolates from the water supply matched the patient's isolate, by both monoclonal antibody subtyping and genomic fingerprinting. None of 116 crew members had significant antibody titers to L. pneumophila serogroup 1. One clinically suspected case of legionnaires' disease and one confirmed case were subsequently diagnosed among passengers cruising on the same ship in November 1995 and October 1996, respectively. This is the first documented evidence of the involvement of a water supply system in the transmission of legionella infection on ships. These cases were identified because of the presence of a unique international system of surveillance and collaboration between public health authorities. (+info)
Risk factors for nosocomial bloodstream infections due to Acinetobacter baumannii: a case-control study of adult burn patients.
Risk factors for Acinetobacter baumannii bloodstream infection (BSI) were studied in patients with severe thermal injury in a burn intensive care unit where A. baumannii was endemic. Of 367 patients hospitalized for severe thermal injury during the study period, 29 patients with nosocomial A. baumannii BSI were identified (attack rate, 7.9%). Cases were compared with 58 matched controls without A. baumannii BSI. The overall mortality rate was 31% among cases and 14% among controls; only two deaths (7%) were considered directly related to A. baumannii BSI. Molecular typing of A. baumannii blood isolates by means of randomly amplified polymorphic DNA analysis and pulsed-field gel electrophoresis revealed the presence of three different strain types. Multivariate analysis showed that female gender (P = .027), total body surface area burn of > 50% (P = .016), prior nosocomial colonization with A. baumannii at a distant site (P = .0002), and use of hydrotherapy (P = .037) were independently associated with the acquisition of A. baumannii BSI in burn patients. These data underscore the need for effective infection control measures for this emerging nosocomial problem. (+info)
Molecular differentiation of Renibacterium salmoninarum isolates from worldwide locations.
Renibacterium salmoninarum is a genospecies that is an obligate pathogen of salmonid fish and is capable of intracellular survival. Conventional typing systems have failed to differentiate isolates of R. salmoninarum. We used two methods to assess the extent of molecular variation which was present in isolates from different geographic locations. In one analysis we investigated possible polymorphisms in a specific region of the genome, the intergenic spacer (ITS) region between the 16S and 23S rRNA genes. In the other analysis we analyzed differences throughout the genome by using randomly amplified polymorphic DNA (RAPD). We amplified the spacer region of 74 isolates by using PCR and performed a DNA sequence analysis with 14 geographically distinct samples. The results showed that the 16S-23S ribosomal DNA spacer region of R. salmoninarum is highly conserved and suggested that only a single copy of the rRNA operon is present in this slowly growing pathogen. DNA sequencing of the spacer region showed that it was the same length in all 14 isolates examined, and the same nucleotide sequence, sequevar 1, was obtained for 11 of these isolates. Two other sequevars were found. No tRNA genes were found. We found that RAPD analysis allows reproducible differentiation between isolates of R. salmoninarum obtained from different hosts and different geographic regions. By using RAPD analysis it was possible to differentiate between isolates with identical ITS sequences. (+info)
Biodiversity of Lactococcus garvieae strains isolated from fish in Europe, Asia, and Australia.
Lactococcus garvieae (junior synonym, Enterococcus seriolicida) is a major pathogen of fish, producing fatal septicemia among fish species living in very diverse environments. The phenotypic traits of L. garvieae strains collected from three different continents (Asia, Europe, and Australia) indicated phenotypic heterogeneity. On the basis of the acidification of D-tagatose and sucrose, three biotypes were defined. DNA relatedness values and a specific PCR assay showed that all the biotypes belonged to the same genospecies, L. garvieae. All of the L. garvieae strains were serotyped as Lancefield group N. Ribotyping proved that one clone was found both in Japan, where it probably originated, and in Italy, where it was probably imported. PCR of environmental samples did not reveal the source of the contamination of the fish in Italy. Specific clones (ribotypes) were found in outbreaks in Spain and in Italy. The L. garvieae reference strain, isolated in the United Kingdom from a cow, belonged to a unique ribotype. L. garvieae is a rising zoonotic agent. The biotyping scheme, the ribotyping analysis, and the PCR assay described in this work allowed the proper identification of L. garvieae and the description of the origin and of the source of contamination of strains involved in outbreaks or in sporadic cases. (+info)
Randomly amplified polymorphic DNA analysis of clinical and environmental isolates of Vibrio vulnificus and other vibrio species.
Vibrio vulnificus is an estuarine bacterium that is capable of causing a rapidly fatal infection in humans. A randomly amplified polymorphic DNA (RAPD) PCR protocol was developed for use in detecting V. vulnificus, as well as other members of the genus Vibrio. The resulting RAPD profiles were analyzed by using RFLPScan software. This RAPD method clearly differentiated between members of the genus Vibrio and between isolates of V. vulnificus. Each V. vulnificus strain produced a unique band pattern, indicating that the members of this species are genetically quite heterogeneous. All of the vibrios were found to have amplification products whose sizes were within four common molecular weight ranges, while the V. vulnificus strains had an additional two molecular weight range bands in common. All of the V. vulnificus strains isolated from clinical specimens produced an additional band that was only occasionally found in environmental strains; this suggests that, as is the case with the Kanagawa hemolysin of Vibrio parahaemolyticus, the presence of this band may be correlated with the ability of a strain to produce an infection in humans. In addition, band pattern differences were observed between encapsulated and nonencapsulated isogenic morphotypes of the same strain of V. vulnificus. (+info)
Arbitrarily primed PCR to type Vibrio spp. pathogenic for shrimp.
A molecular typing study on Vibrio strains implicated in shrimp disease outbreaks in New Caledonia and Japan was conducted by using AP-PCR (arbitrarily primed PCR). It allowed rapid identification of isolates at the genospecies level and studies of infraspecific population structures of epidemiological interest. Clusters identified within the species Vibrio penaeicida were related to their area of origin, allowing discrimination between Japanese and New Caledonian isolates, as well as between those from two different bays in New Caledonia separated by only 50 km. Other subclusters of New Caledonian V. penaeicida isolates could be identified, but it was not possible to link those differences to accurate epidemiological features. This contribution of AP-PCR to the study of vibriosis in penaeid shrimps demonstrates its high discriminating power and the relevance of the epidemiological information provided. This approach would contribute to better knowledge of the ecology of Vibrio spp. and their implication in shrimp disease in aquaculture. (+info)