Immune and proliferative cellular responses to Helicobacter pylori infection in the gastric mucosa of Mexican children.

BACKGROUND: Helicobacter pylori infection occurs mostly during childhood, but few studies on this age group have addressed the innate immune and the proliferative response to this infection. Mexico has a high H. pylori prevalence in children, but a low risk of gastric cancer. The aim of this work was to study the cellular responses of the gastric mucosa to this infection in Mexican children. METHODS: Antral and corpus gastric biopsies were obtained from 44 H. pylori-infected children (mean age 12 +/- 3.2 years) and 44 uninfected children (mean age 10 +/- 3 years). Mucosal cellular responses were studied by immunohistochemistry, using anti-Ki67 antibodies for proliferation studies, antihuman tryptase for mast cells, and antihuman CD68 for macrophages. T and B lymphocytes were stained with a commercial integrated system. The intensity of cellular responses was estimated histologically using the software KS300. RESULTS: Epithelium proliferation and infiltration of macrophages and T and B lymphocytes were significantly higher in H. pylori-infected than in uninfected children. A balanced increase of CD4, CD8, and CD20 lymphocytes was observed in infected children. However, activated mast cells were decreased, and infiltration of neutrophil and mononuclear cells was low. Epithelial proliferation was associated with polymorphonuclear infiltration but not with infiltration of macrophages or lymphocytes. Inflammation and proliferation was higher in CagA (+)-infected children. CONCLUSIONS: Mexican children respond to H. pylori infection with a low inflammatory response, a balanced increase of T and B lymphocytes, and a high regenerative activity.

Association of Mycoplasma hominis and Ureaplasma urealyticum with some indicators of nonspecific vaginitis.

The purpose of this study was to determine the isolation rates of Mycoplasma hominis and Ureaplasma urealyticum from three populations of women and also to relate the presence of these microorganisms with some indicators of nonspecific vaginitis. Three hundred vaginal swabs were taken from delivery, pregnant and control (not pregnant) women. Cultures were done in E broth supplemented with arginine or urea. M. hominis was isolated in 5% at delivery, 12% from pregnant and 5% from control women and U. urealyticum was isolated in 21%, 31% and 28% respectively. There was statistical difference in the isolation rate of M. hominis in pregnant women respect to the other groups. Both microorganisms were more frequently isolated in women with acid vaginal pH, amine-like odor in KOH test, clue cells and leucorrhea. M. hominis was isolated in 17% and U. urealyticum in 52% from women with nonspecific vaginitis. M. hominis was isolated in 2% and U. urealyticum in 13% from women without nonspecific vaginitis. Although the presence of clue cells and amine-like odor in KOH test have relationship with Gardnerella vaginalis, these tests could also suggest the presence of these mycoplasmas.

[Mexican phenotype and genotype Vibrio cholerae 01]. / Vibrio cholerae 01 fenotipos y genotipos México.

This paper presents the phenotypical and genotypical characterization of 26922 Vibrio cholerae 01 strains isolated in Mexico from 1991 to 1993. All strains isolated were El Tor biovar. Strains were sensitive to antibiotics excluding furazolidone, streptomycin and sulfisoxasole to which we found resistance in 97% and we are using this characteristic as epidemiological markers. We detected a marked change in frequency of Inaba serotype from 1991, when it was dominant, with 99.5%, until 1992 when Ogawa serotype turned to be dominant with 95% of isolates. All Vibrio cholerae 01 strains, except one Ogawa strain, were to igenic, and V. choleraeno 01 were not toxigenic by ELISA, PCR and cell culture tests. Dominant ribotype was 5, but we found some strains with 6a pattern and two with ribotype 12. We are searching for ribotype 2 among hemolytic strains in order to learn if there is any relation to Gulf Coast strains prevalent in the USA, but until now we have not found any V. cholerae ribotype 2 in our isolates. Even if rapid tests are recommended for immediate diagnosis of cholera, it is necessary to continue bacterial isolation in order to have strains for phenotyping and genotyping studies that may support epidemiological analysis.

Experimental arthritis induced by Mycoplasma pneumoniae in rabbits.

Experimental arthritis in rabbits was induced by M. pneumoniae. We compared it with the arthritis produced by well known animal arthritogenic agents (M. pulmonis and M. arthritidis). Mycoplasmas were detected in the knee joint by different techniques. M. pneumoniae and M. pulmonis produced an acute arthritis that resolved in 2 weeks while, M. arthritidis produced a chronic arthritis. Live M. pneumoniae and M. pulmonis were recovered from the joint during all the experiments. No live M. arthritidis was detected. Live mycoplasmas play an important role in acute arthritis. A similar inflammatory pattern was shown by M. pneumoniae and M. pulmonis. This animal model could be helpful in the study of arthritis induced by a human pathogen mycoplasma.

[Diagnosis of streptococcal pharyngo-tonsillitis: clinical criteria or coagglutination?]. / Diagnóstico de faringoamigdalitis estreptocóccica: criterio clínico o coaglutinación?

With the purpose of evaluating the usefulness of clinical data and a coagglutination test for the diagnosis of streptococcal pharyngeal tonsillitis, a study was carried out comparing both methods with the standard pharynx culture (gold standard). One hundred and forty-one patients clinically diagnosed with pharyngeal tonsillitis were analyzed. 80 other patients diagnosed with rhino-pharyngitis were used as control groups as well as a group of 66 healthy patients. It was found that the presence of pus in the tonsils and the absence of rhinorrhea and/or a productive cough were isolated clinical variables which showed a significant difference when comparing those cases with a positive or a negative culture (P less than 0.01). These clinical data had a sensitivity and adequate negative predictive values (68 to 83% and 90 to 92%, respectively); specificity was 44 to 74% and the positive predictive value from 24 to 36%. The gathering of combined clinical indexes with different symptoms and signs, were not greater than isolated data. The coagglutination test in those cases of pharyngeal tonsillitis showed greater better specificity (98%) and positive predictive value (93%), but saw no improvement in sensitivity (72%) nor in the negative predictive value (91%), which is why when faced with a negative coagglutination test, it is still necessary to perform a throat culture due to the risk which the patient may be exposed to when no treatment is given. The analysis of the advantages and disadvantages in the routine use of coagglutination and cultures in their particular cases, allows us to conclude that in daily clinical practice the use of clinical criteria is of greater usefulness.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of Clostridium difficile and its cytotoxin in infants in Mexico.

The incidence of Clostridium difficile and its cytotoxic activity were determined in the feces of 122 children under 1 year of age. Samples were obtained from children receiving antibiotics and with (52 cases) or without (26 cases) diarrhea, from children with diarrhea who did not receive antibiotics (22 cases), and from healthy children (22 cases). Isolation of C. difficile in feces from children in all groups was similar (mean 23.4%) except for the group with non-antibiotic-associated diarrhea (4.5%). In both groups of children receiving antibiotics, with or without diarrhea, the cytotoxin was detected in 7.6% of the cases. In the group with non-antibiotic-associated diarrhea, none of the samples was positive for cytotoxicity. In healthy children, cytotoxin was positive in 4.5% of the cases.