Substitutions in Penicillin-Binding Protein 1 in Amoxicillin-Resistant Helicobacter pylori Strains Isolated from Korean Patients

BACKGROUND/AIMS: A worldwide increase in amoxicillin resistance in Helicobacter pylori is having an adverse effect on eradication therapy. In this study, we investigated the mechanism of the amoxicillin resistance of H. pylori in terms of amino acid substitutions in penicillin-binding protein 1 (PBP1). METHODS: In total, 150 H. pylori strains were isolated from 144 patients with chronic gastritis, peptic ulcers, or stomach cancer. The minimum inhibitory concentrations (MICs) of the strains were determined with a serial 2-fold agar dilution method. The resistance breakpoint for amoxicillin was defined as >0.5 microg/mL. RESULTS: Nine of 150 H. pylori strains showed amoxicillin resistance (6%). The MIC values of the resistant strains ranged from 1 to 4 microg/mL. A PBP1 sequence analysis of the resistant strains revealed multiple amino acid substitutions: Val16-->Ile, Val45-->Ile, Ser414-->Arg, Asn562-->Tyr, Thr593-->Ala, Gly595-->Ser, and Ala599-->Thr. The natural transformation of these mutated genes into amoxicillin-sensitive strains was performed in two separate pbp1 gene segments. A moderate increase in the amoxicillin MIC was observed in the segment that contained the penicillin-binding motif of the C-terminal portion, the transpeptidase domain. CONCLUSIONS: pbp1 mutation affects the amoxicillin resistance of H. pylori through the transfer of the penicillin-binding motif.

Comparative analysis of two-dimensional electrophoresis maps (2-DE) of Helicobacter pylori from Brazilian patients with chronic gastritis and duodenal ulcer: a preliminary report

O Helicobacter pylori é uma bactéria reconhecida como a principal causa de úlcera péptica e gastrite crônica. Recentemente, o proteoma do H. pylori tem sido desenvolvido visando identificar fatores patogênicos relacionados ao microorganismo. Neste estudo preliminar, cepas de H. pylori foram isoladas de fragmento de mucosa gástrica de pacientes com úlcera duodenal e gastrite crônica. Posteriormente, realizou-se uma análise proteômica parcial dessas cepas, através da lise bacteriana e da separação de proteínas através da eletroforese de duas dimensões (2-DE). Por análise comparativa, foi possível verificar a expressão protéica diferencial entre os dois mapas 2-DE obtidos. Os dados poderão ser úteis para esclarecer a importância de diferentes proteínas relacionadas à patogênese da bactéria. Este estudo será complementado utilizando um maior número de amostras e a identificação protéica do H. pylori através da espectrometria de massa do tipo MALDI-TOF.

Crecimiento y evolución del Helicobacter pylori / Growth and evolution of Helicobacter pylori

El género Helicobacter tiene una historia relativamente reciente. Su protagonismo data del año 1982, fecha en la que el Helicobacter Pylori se aisló por primera vez de paciente humanos. Esta bacteria, inicialmente, se incluyó en el género Campylobacter y se la denominó Campylobacter Pylori o Piloridis. Posteriormente en el año 1989, se separo de este género y se creó uno nuevo el género Helycobacter, al que actualmente pertenecen varias especies. Los expertos en microbiología le asignaron este término por su forma de hélice in vivo y sus caracteres de bacteria in vitro, ya que encontraron que la denominación Campylobacter era errónea en vista del contenido de ácidos grasos de su pared y por el análisis del ADN se dieron cuenta que la bacteria no pertenecía a los Campylobacter.

Lower density of antral somatostatin-immunoreactive cells in the digestive form of chronic Chagas' disease

Patients with the digestive form of chronic Chagas' disease exhibit abnormally increased gastrin release, possibly caused by antral gastrin cell (G cell) hyperfunction. In order to identify the mechanisms underlying this abnormality, we used an immunohistochemical method to assess the population of antral somatostatin-producing cells (D cells) in chagasic patients, since somatostatin is known to be the main inhibitory factor of gastrin secretion. Samples (N = 11) of endoscopic antral biopsies taken from 16 Chagas' disease patients and 13 control subjects were studied. Antral D and G cell populations were determined by an immunohistochemical technique using highly specific antibodies against somatostatin and gastrin. There was no significant difference between Chagas' disease and control groups regarding G cell population (number of cells/mm reported as median (range): 70.0 (23.7-247.0) vs 98.1 (52.7-169.4), P>0.10). In contrast, the number of antral D cells in Chagas' disease patients was significantly lower than in controls (l6.4 (6.9-54.4) vs 59.3 (29.6-113.8), P<0.05). Chronic superficial gastritis and infection with Helicobacter pylori were more frequent in chagasic patients than in controls, but there was no demonstrable association between these factors and the reduction of the number of antral D cells. These data suggest that reduction in the number of antral somatostatin-producing cells, which should lead to reduced inhibition of gastrin cell activity, may play a role in the increased gastrin secretion observed in Chagas' disease patients.

Infección por helicobacter pylori en niños

Helicobacter pylori es un bacilo Gram-negativo espiralado que produce grandes cantidades de ureasa que le confiere un medio óptimo para la colonización de mucosa gástrica. En la actualidad se le considera como el mecanismo principal del daño de la mucosa gástrica y se ha identificado en 80 por ciento de los pacientes con gastritis y en 95 por ciento de aquéllos con úlcera duodenal. Muchos niños infectados son asintomáticos, sin embargo, síntomas como dolor abdominal recurrente, vómito, hematemesis se asocian frecuentemente a esta infección. La infección crónica por esta bacteria está relacionada con el desarrollo de cáncer gástrico principalmente con linfoma tipo MALT; por estas implicaciones se consideró importante hacer un diagnóstico precoz y un tratamiento oportuno como a continuación se describe.

Isolation and characterization of Helicobacter pylori strains from peptic ulcer patients in Dhaka, Bangladesh.

To study the association of Helicobacter pylori with peptic ulcer and the associated histopathological changes, to characterize the isolated strains in terms of their protein profile, 83 peptic ulcer cases were studied. A high association of H pylori with peptic ulcer (duodenal ulcer 77%, gastric ulcer 75%) and gastritis (74%) was observed. Age and smoking did not have any relationship with H pylori infection. The infection was predominantly associated with the 'quiescent' form of chronic gastritis. Comparative sodium dodecyl sulfate polyacrylamide gel electrophoresis of whole cell extracts of the local isolates and a reference strain from Australia showed a general homogeneity between the strains with obvious interstrain differences. However, the difference between the local isolates and the reference strain was more marked. Significant association of H. pylori with peptic ulcer along with strain variations were observed.

"Helicobacter pylori": erradicaçäo em curto prazo com o esquema Belo Horizonte modificado / Helicobacter pylori: short-term eradication with modified Belo Horizonte scheme

Após a constataçao de que a erradicaçao do H. pylori está correlacionada com a cura da doença ulcerosa, numerosos esquemas terapêuticos têm sido testados na procura de um tratamento ideal.Como os estudos in vitro mostram número elevado de cepas de H. pylori resistentes ao metronidazol, no Brasil, foram comparados dois grupos com diferentes esquemas. Sessenta pacientes (34 homens, idade média de 42 anos), positivos para o H. pylori, foram divididos em dois grupos: A) associaçao de furazolidona 600mg/dia, amoxicilina 1.500 mg/dia e subcitrato de bismuto 480mg/dia (esquema Belo Horizonte modificado); B) amoxicilina 2.000mg/dia, metronidazol 1.250mg/dia e subcitrato de bismuto 480mg/dia (esquema Sydney).A presença do H. pylori foi avaliada pelo teste da urease e pelo teste respiratório. Dos 60 pacientes, 49 (81 por cento) completaram o estudo (26 do grupo A e 23 do grupo B). Quatro pacientes (três no grupo A e um no grupo B) nao retornaram para controle. Sete pacientes (um no grupo A e seis no grupo B) interromperam o tratamento por causa de efeitos colaterais. No grupo A, o H. pylori foi erradicado em 17 (65,4 por cento) dos pacientes e, no grupo B, em 17 (73,9 por cento), nao havendo diferença estatisticamente significativa, permitindo a conclusao de que o esquema Belo Horizonte modificado é uma alternativa satisfatória na terapêutica anti-H.pylori.