[Analysis of molecular fingerprint and virulence factors of Helicobacter pylori strains]. / Análise das impressões digitais de DNA e de fatores de virulência de linhagens de Helicobacter pylori.

BACKGROUND: Helicobacter pylori is now accepted as the most important agent of gastritis in humans, as well as a risk factor for peptic ulcer disease and gastric carcinoma. The outcome of the infection is related to several factors, among them bacterial ones such as cagA and vacA s1m1 genotype. Random amplified polymorphic DNA (RAPD)-PCR, has been used to generate DNA fingerprints to evaluate similarity among strains within a bacterial species. AIM: To assess the association between RAPD fingerprinting, virulence factors and the disease. METHODS: H. pylori was isolated from 112 patients (41 with gastritis; 19 with gastric ulcers; 38 with duodenal ulcer disease; and 14 with gastroesophageal reflux disease). Allelic variants of cagA and vacA were identified using the polymerase chain reaction (PCR) and the fingerprints were generated by RAPD-PCR. RESULTS: There was a strong association between the genotype vacA s1m1 and duodenal ulcers. Although RADP-PCR is a very useful tool in genotyping H. pylori, no significant correlation between the diseases studied and DNA fingerprint was detected neither with fingerprint and different vacA and, cagA genotypes. CONCLUSIONS: The extension of our analysis to patients with well-characterized gastric diseases may provide significant information on the relationship between vacA genotypes and clinical outcomes of H. pylori infection.

Análise das impressões digitais de DNA e de fatores de virulência de linhagens de Helicobacter pylori / Analysis of molecular fingerprint and virulence factors of Helicobacter pylori strains

RACIONAL: Helicobacter pylori é hoje aceito como o principal agente etiológico de gastrite em seres humanos e fator de risco para úlcera péptica e câncer gástrico. A evolução da infecção está relacionada a diversos fatores, inclusive bacterianos, como presença do gene cagA e o genótipo vacA s1m1, associados ao desenvolvimento de úlcera e adenocarcinoma gástrico. A técnica de RAPD ("random amplified polimorphic") tem sido amplamente utilizada para obtenção de impressões digitais de DNA para examinar a similaridade entre linhagens. OBJETIVOS: Avaliar a presença de cagA e alelos do vacA em amostras de H. pylori e associar os achados com a doença apresentada e também investigar possível clonicidade entre os fatores de virulência e as doenças com a impressão digital de DNA gerada pelo RAPD-PCR. MÉTODOS: Foram incluídas 112 amostras provenientes de pacientes com diferentes laudos endoscópicos: gastrite (n = 41), esofagite de refluxo (n = 14), úlcera gástrica (n = 19) e úlcera duodenal (n = 38). A análise dos fatores de virulência da bactéria foi feita por PCR e as impressões digitais de DNA foram estabelecidas pelo método de RAPD-PCR. RESULTADOS: Os resultados obtidos indicam que houve uma associação significativa entre úlcera duodenal e o mosaico vacA s1m1. Analisando-se os padrões de bandas geradas pelo RAPD-PCR, sete diferentes dendogramas foram construídos e não foi possível detectar associação significativa entre os agrupamentos, sugerindo que as amostras não possuem perfil clonal. CONCLUSÃO: Os resultados reforçam a importância do gene vacA como um marcador de virulência do H. pylori. O RAPD da impressão digital de DNA realizado foi incapaz de associar o padrão de bandas com as enfermidades e os genótipos de vacA e cagA.

BACKGROUND: Helicobacter pylori is now accepted as the most important agent of gastritis in humans, as well as a risk factor for peptic ulcer disease and gastric carcinoma. The outcome of the infection is related to several factors, among them bacterial ones such as cagA and vacA s1m1 genotype. Random amplified polymorphic DNA (RAPD)-PCR, has been used to generate DNA fingerprints to evaluate similarity among strains within a bacterial species. AIM: To assess the association between RAPD fingerprinting, virulence factors and the disease. METHODS: H. pylori was isolated from 112 patients (41 with gastritis; 19 with gastric ulcers; 38 with duodenal ulcer disease; and 14 with gastroesophageal reflux disease). Allelic variants of cagA and vacA were identified using the polymerase chain reaction (PCR) and the fingerprints were generated by RAPD-PCR. RESULTS: There was a strong association between the genotype vacA s1m1 and duodenal ulcers. Although RADP-PCR is a very useful tool in genotyping H. pylori, no significant correlation between the diseases studied and DNA fingerprint was detected neither with fingerprint and different vacA and, cagA genotypes. CONCLUSIONS: The extension of our analysis to patients with well-characterized gastric diseases may provide significant information on the relationship between vacA genotypes and clinical outcomes of H. pylori infection.

Mutations in the 23S rRNA gene are associated with clarithromycin resistance in Helicobacter pylori isolates in Brazil.

BACKGROUND: Resistance of Helicobacter pylori to clarithromycin has been associated with A2142G and A2143G point mutations in the 23S rRNA gene. Thus, the purpose of the present study was to determine the prevalence of each mutation in 52 clarithromycin-resistant H. pylori strains and to characterize the influence each type of mutation on the MIC. METHODS: The MIC for clarithromycin was determined by the agar dilution method, and the point mutations of H. pylori were detected by PCR followed by restriction fragment length polymorphism. RESULTS: Clarithromycin MICs ranged from 2 to >256 microgram ml-1 among the 52 strains included in this study. Both the A2142G and the A2143G mutations were present in 94.2% of clarithromycin-resistant H. pylori strains examined. A relationship was observed between the presence of the A2142G mutation and the highest MIC values (p = 0.01). CONCLUSION: In an H. pylori-infected population, the A2142G mutation may incur to a greater probability of treatment failure if clarithromycin is used.