Frequency of vacA, cagA and babA2 virulence markers in Helicobacter pylori strains isolated from Mexican patients with chronic gastritis.

BACKGROUND: Helicobacter pylori has been strongly associated with chronic gastritis, peptic and duodenal ulcers, and it is a risk factor for gastric cancer. Three major virulence factors of H. pylori have been described: the vacuolating toxin (VacA), the cytotoxin-associated gene product (CagA) and the adhesion protein BabA2. Since considerable geographic diversity in the prevalence of H. pylori virulence factors has been reported, the aim of this work was to establish the H. pylori and vacA, cagA and babA2 gene status in 238 adult patients, from a marginal urban area of Mexico, with chronic gastritis. METHODS: H. pylori was identified in cultures of gastric biopsies by nested PCR. vacA and cagA genes were detected by multiplex PCR, whereas babA2 gene was identified by conventional PCR. RESULTS: H. pylori-positive biopsies were 143 (60.1%). All H. pylori strains were vacA+; 39.2% were cagA+; 13.3% were cagA+ babA2+ and 8.4% were babA2+. Mexican strains examined possessed the vacA s1, m1 (43.4%), s1, m2 (24.5%), s2, m1 (20.3%) and s2, m2 (11.9%) genotypes. CONCLUSION: These results show that the Mexican patients suffering chronic gastritis we have studied had a high incidence of infection by H. pylori. Forty four percent (63/143) of the H. pylori strains analyzed in this work may be considered as highly virulent since they possessed two or three of the virulence markers analyzed: vacA s1 cagA babA2 (9.8%, 14/143), vacA s1 babA2 (4.9%, 7/143), and vacA s1 cagA (29.4%, 42/143). However, a statistically significant correlation was not observed between vacAs1, cagA and babA2 virulence markers (chi2 test; P > 0.05).

Two or more enteropathogens are associated with diarrhoea in Mexican children.

BACKGROUND: Diarrhoeal diseases constitute a major public health problem, particularly in the developing world, where the rate of mortality and morbidity is very high. The purpose of this study was to conduct a 2 years and 3 months study in order to determine the prevalence of five enteropathogen diarrheogenic agents in Mexico City. METHODS: Faecal samples were obtained from 300 Mexican children diagnosed as positive for diarrhoea, aged > 2 to < 12 years old, and from 80 children matched for age but with no symptoms of the disease (control group). Two multiplex PCR were used to detect Escherichia coli, Salmonella spp., and Shigella spp. In addition, the two protozoan parasites Entamoeba histolytica/Entamoeba dispar and Giardia intestinalis were detected by conventional methods. RESULTS: All diarrhoeal samples were positive for one or more enteropathogens. The most common enteropathogens in diarrhoeal samples were E. histolytica/E. dispar (70.3%), Salmonella (ohio 28.3%; typhimurium 16.3%; infantis 8%; anatum 0.6%; Newport 0.3%), G. intestinalis (33%), E. coli (ETEC 13.3%; EPEC 9.3%; VTEC 8.6%; EIEC 1%) and Shigella spp. (flexneri 1.6%, sonnei 1%). Infections by two (24%) three (16%) and four (12%) pathogens were observed. CONCLUSION: This study revealed that 52% of the patients were infected by more than one enteropathogen, notably E. histolitica/E. dispar and Salmonella ohio. These results are useful for clinicians to improve the empiric treatment used in such cases.

Actinobacillus pleuropneumoniae metalloprotease: cloning and in vivo expression.

The complete amino acid and nucleotide sequence of a secreted metalloprotease produced by Actinobacillus pleuropneumoniae serotype 1 is reported. A clone showing proteolytic activity in cell-free culture media was selected from a genomic library of A. pleuropneumoniae serotype 1 in pUC 19. The sequence obtained contained an open reading frame encoding a protein with 869 amino acids. This protein was identified as a zinc neutral-metalloprotease belonging to the aminopeptidase family, with a predicted molecular weight of approximately 101 kDa. This sequence showed high homology with other predicted or sequenced aminopeptidases reported for different Gram-negative bacteria. Expression of the protease was observed in lung tissue from pigs that died of porcine pleuropneumonia suggesting a role in pathogenesis.

Susceptibility to 5-fluorocytosine, miconazole and amphotericin B of Candida albicans strains isolated from the throat of non-AIDS patients.

Eighty Candida albicans strains, isolated from throat of patients at the Universitary Clinic of the Faculty of Superior Studies Iztacala of the National Autonomous University of Mexico, were analyzed. They were identified by microscopic and colony morphologies, germ tube test, and by auxanogram and zimogram. Minimal inhibitory concentrations (MIC) of 5-fluorocytosine, miconazole and amphotericin B were determined by microtiter broth dilution. MIC frequency distribution of 5-fluorocytosine showed a single peak (0.25-8.0 microg/ml), with 65% susceptible strains (MIC < or = 1.0 < or =g/ml) and 35% intermediate susceptible strains (MIC = 1.1-8 microg/ml). MIC frequency distribution of miconazole was threemodal with 6.25% susceptible (MIC = 1.562 microg/ml), 48.75% intermediate susceptible (MIC = 3.125-12.5 microg/ml), and 45% resistant (MIC = 25-50 microg/ml) strains. All strains were susceptible to amphotericin B (MIC= 0.0156-0.125 microg/m). These results shows that amphotericin B was the more active antimycotic, followed by 5-fluorocytosine, against the strains analyzed, and that miconazole was the less effective one.