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Biomedical subjects

Adriana Santos

Publications and source records attributed to Adriana Santos.

12 recordsLinked to original sources
PubMed2005

Detection of mutations associated with macrolide resistance in thermophilic Campylobacter spp. by real-time PCR.

Two point mutations (A2074C and A2075G) in the 23S rRNA gene of Campylobacter coli and C. jejuni are associated with erythromycin resistance. A real-time fluorescence resonance energy transfer PCR assay using a melting curve analysis was developed to identify these two point mutations and the wild-type genotype in thermophilic Campylobacter species such as C. coli, C. jejuni, and C. lari. Concerning these species, 141 strains were tested and a result obtained in 140 (99.3%). A single genotype was detected in 133 cases and two genotypes in seven cases. There was an agreement with the phenotypic methods except for one C. coli strain that was not amplified during the PCR assay. The A2075G mutation was mainly found among the 92 resistant strains tested (95.6%) and the A2074C mutation only twice (2.2%). One C. jejuni strain (1.1%) harbored both mutations on the same 23S rDNA copy. When compared to the phenotypic tests, the new real-time PCR assay was able to detect the correct genotype, in all cases except one (1.1%). This assay is more sensitive and more rapid than other PCR assays, the entire procedure taking less than 2 hr.

Campylobacter coli↗
PubMed2004

IL1B and IL1RN polymorphic genes and Helicobacter pylori cagA strains decrease the risk of reflux esophagitis.

BACKGROUND & AIMS: Proinflammatory interleukin (IL)-1 gene polymorphisms associated with high levels of IL-1beta activity increase the risk for hypochlorhydria and distal gastric carcinoma. The aim of this study was to evaluate whether carriers of these polymorphic genes are protected against gastroesophageal reflux disease (GERD). TNFA-308 polymorphisms were also studied. METHODS: We prospectively evaluated 385 patients without gastric cancer and peptic ulcer. Of these patients, 383 (98 with GERD and 285 controls) were successfully genotyped for all cytokines studied. The cagA status of Helicobacter pylori isolates was determined by polymerase chain reaction (PCR). IL1B-511/-31, IL1RN, and TNFA-308 polymorphisms were genotyped by PCR, PCR/restriction fragment length polymorphism, or PCR/confronting 2-pair primers. Histologic gastritis was assessed according to the updated Sydney system. The role of the proinflammatory cytokine genotypes in the genesis of GERD was evaluated before and after stratification by H. pylori status in logistic regression models controlling for confounding factors. RESULTS: IL1B-31 (a near-complete linkage disequilibrium between polymorphism at -31 and -511 was found) and IL1RN*2 allele polymorphisms were associated with GERD. After stratification, in the group of H. pylori-positive patients, cagA-positive status, IL1B-31 polymorphic alleles, IL1RN*2 alleles, and the degree of corpus gastritis were negatively associated with GERD. In the H. pylori-negative group, IL1B-31C/C genotype was inversely associated with GERD even after adjustment for age and sex. CONCLUSIONS: This study provides evidence supporting the independent protective role of cagA-positive H. pylori status and IL1B and ILRN allele polymorphisms against GERD.

Adult↗
PubMed2003

Transmission of Helicobacter pylori infection in families of preschool-aged children from Minas Gerais, Brazil.

We evaluated the role of the family in the transmission of Helicobacter pylori infection in preschool-aged children from a rural district in the State of Minas Gerais, Brazil. Sixty-six families (66 index children, 63 mothers, 60 fathers and 134 siblings), defined as at least one parent living in the same household with at least one offspring up to 8 years old, were studied. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by logistic regression controlling for age, gender, number of children in household and H. pylori status of the father, mother and siblings. The prevalence of the infection was 69.7% (469 of 673) and it increased with age (P < 0.001). Positive mothers were a strong and independent risk factor for infection (OR 22.70; 95% CI 2.31-223.21). Positive siblings were also positively associated with infection (OR 1.81; 95% CI 1.01-3.30).

Adolescent↗
PubMed2003

Real-time PCR assay for rapid and accurate detection of point mutations conferring resistance to clarithromycin in Helicobacter pylori.

The main cause of failure of Helicobacter pylori eradication therapy is resistance to clarithromycin. The resistance is due to three point mutations in two positions on the 23S rRNA (A2142C, A2142G, and A2143G). Our aim was to develop a rapid and accurate method to detect these mutations directly on biopsy specimens. We developed a real-time PCR that included a simultaneous detection of the amplicons by hybridization of two probes labeled with LC-Red and fluorescein by using the fluorescence resonance energy transfer (FRET) technology and melting curve analysis with the LightCycler thermocycler. The assay was first applied successfully on reference strains, reference plasmids, and H. pylori-negative biopsies. Biopsies from 200 patients having failed a first eradication attempt and for whom the H. pylori strain was available were then tested with the new assay. A result was obtained in 199 cases; a single genotype was detected in 157 cases, two genotypes were detected in 41 cases, and three genotypes were detected in one case. There were, in total, seven discrepancies between the real-time PCR and the phenotypic method of determination of clarithromycin susceptibility, and in an additional four cases the two phenotypic methods were in disagreement. PCR-restriction fragment length polymorphism was applied to a sampling of biopsies, including all of the cases with multiple genotypes and all the cases with discrepant results. Finally, in four cases with discrepant results, the real-time PCR detected the resistant population at a concentration so low that it could not be detected by the phenotypic method, while in three cases other mutations could be involved. This assay had an accuracy at least as satisfactory as that of the phenotypic tests and could be performed within 2 h, allowing it to be used before the administration of therapy in the case of a first H. pylori eradication.

Anti-Bacterial Agents↗
PubMed2003

Accuracy of a commercial enzyme-linked immunosorbent assay for CagA in patients from Brazil with and without gastric carcinoma.

We validated a commercial enzyme-linked immunosorbent assay for the detection of anti-CagA antibodies in Brazilian patients with Helicobacter pylori infection. The test presented high sensitivity (97.4%) and specificity (88.9%) when employed in patients without gastric carcinoma. However, in gastric carcinoma patients, the test was neither sensitive nor specific enough to detect cagA-positive H. pylori infection.

Antigens, Bacterial↗
PubMed2003

New pathogenicity marker found in the plasticity region of the Helicobacter pylori genome.

Comparison of gastric carcinoma and gastritis isolates showed the presence of genes, probably carcinoma associated (JHP947 and JHP940), that are situated in a Helicobacter pylori genome region (45 kb in J99 and 68 kb in 26695) called the "plasticity region." This region presents a great variability of DNA sequences. We investigated, by PCR, the presence of the JHP940 and JHP947 genes, as well as the presence of a third gene which seems to be associated with gastritis (HP986), on H. pylori strains isolated from 200 Brazilian patients, 79 of whom had gastric carcinomas and 53 of whom had duodenal ulcers, to confirm this association. Gastritis isolates (n = 68) were included as a control. We also evaluated if these genes were related to the virulence-associated cagA genotype. The present methodology did not permit definitive conclusions to be reached regarding the association between the JHP940 gene and gastric carcinoma or between the HP986 gene and gastritis. However, we showed that the JHP947 gene might be implicated in the development of both duodenal ulcer and gastric carcinoma. The presence of the JHP947 gene was associated with the cagA-positive genotype. The JHP947 gene is a novel virulence marker candidate of H. pylori.

Bacterial Proteins↗
PubMed2003

babA2- and cagA-positive Helicobacter pylori strains are associated with duodenal ulcer and gastric carcinoma in Brazil.

The babA2 and cagA genes were investigated in 208 Brazilian Helicobacter pylori strains. A strong association between babA2 and duodenal ulcer or gastric carcinoma was observed, even after adjusting for confounding factors, such as age, gender, and cagA status. cagA-positive strains were also independently associated with H. pylori-related diseases.

Adhesins, Bacterial↗
PubMed2002

Factors associated with treatment failure of Helicobacter pylori infection in a developing country.

BACKGROUND: Although no regimen can eradicate in 100% of patients, factors that may affect the eradication rates have been poorly studied. GOAL: To evaluate factors associated with treatment failure. STUDY: One hundred patients were treated with pantoprazole plus clarithromycin and furazolidone for eradication. Clarithromycin and furazolidone resistance was evaluated by the agar dilution method. Point mutations in 23S rRNA genes related to clarithromycin resistance were investigated by polymerase chain reaction and restriction length fragment polymorphism and A by polymerase chain reaction. The data were analyzed by logistic regression. RESULTS: eradication occurred in 85 of 97 patients who completed the treatment (87.6%; 95% CI = 79.0-93.1). All strains were susceptible to furazolidone, and nine were resistant to clarithromycin (A2142G or A2143G mutation was detected in all of them). The treatment failure was significant and independently associated with clarithromycin resistance (OR = 7.79; 95% CI = 1.73-35.01), A-negative status (OR = 4.81; 95% CI = 1.14-20.14), and male gender (OR = 4.20; 95% CI = 1.01-17.78), but not with the type of disease, mean age, smoking, alcohol consumption, and the degree of the antral and oxyntic gastritis. CONCLUSION: Resistance to clarithromycin, A-negative status, and gender were predictive factors of eradication failure.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2002

Helicobacter pylori primary resistance to metronidazole and clarithromycin in Brazil.

Helicobacter pylori resistance to metronidazole was detected in 107 (52.97%) of 202 strains. Twenty (9.85%) strains, 18 of them harboring 23S ribosomal DNA mutations, were resistant to clarithromycin. Metronidazole resistance was associated with female gender. Resistance to metronidazole and resistance to clarithromycin were associated. Increasing clarithromycin resistance rates were observed over time.

Anti-Bacterial Agents↗
PubMed2002

Role of corpus gastritis and cagA-positive Helicobacter pylori infection in reflux esophagitis.

Considering that the role of Helicobacter pylori infection in gastroesophageal reflux and reflux esophagitis (GERD) is still controversial and that the role of virulence markers of the bacterium has not been evaluated in most studies of GERD, we investigated the association among H. pylori infection with cagA-positive and -negative strains, corpus gastritis, and GERD in a large group of patients by controlling for confounding factors. We studied prospectively 281 consecutive adult patients: 93 with GERD and 188 controls. H. pylori infection status was diagnosed by culture, by the preformed urease test, with a carbolfuchsin-stained smear, and by histology. The cagA status was determined by PCR of H. pylori isolates and gastric biopsy specimens. H. pylori infection was diagnosed in 191 (68.0%) of 281 patients. Among the 93 patients with GERD, 84 presented with mild or moderate esophagitis and 9 presented with severe esophagitis. In the multivariate analysis, the age of the patients and the degree of oxyntic gastritis were associated with GERD. Among the strains isolated from patients with GERD and from the control group, 24.4 and 66.9%, respectively, were positive for cagA (P < 0.001). Compared to infection with cagA-negative strains, infection with cagA-positive H. pylori strains was associated with a more intense gastritis in the corpus (P = 0.001). cagA status (odds ratio [OR] = 0.16, 95% confidence interval [CI] = 0.07 to 0.40), gastritis of the corpus (OR = 0.69, 95% CI = 0.48 to 0.99), and age (OR = 1.04, 95% CI = 1.01 to 1.07) were associated with GERD. In conclusion, the study provides evidence supporting the independent protective roles of cagA-positive H. pylori strains and the degree of corpus gastritis against GERD.

Adolescent↗