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S Giono-Cerezo

Publications and source records attributed to S Giono-Cerezo.

15 recordsLinked to original sources
PubMed2001

A comparison of Lewis x and Lewis y expression in Helicobacter pylori obtained from children and adults.

There are no reports, to our knowledge, on the expression of Lewis (Le) antigens in Helicobacter pylori isolates from children. The aim of this study was to compare the expression of Le antigens by H. pylori isolates from children and from adults. Totals of 278 clones from 22 children with recurrent abdominal pain and 293 clones from 22 adults with (n=10) or without (n=12) duodenal ulcer were studied. Expression of Le(x) and Le(y) antigens was determined by ELISA, using monoclonal anti-Le antibodies. The Le phenotype of the patients was determined in gastric juice with a hemagglutination assay. Clones expressing Le(x) were more common in children than in adults (55.4% vs. 33.4%, respectively; P<.001), and Le(y) was more common in adults than in children (81.6% vs. 66%, respectively; P<.01). A trend analysis showed a significant decline in frequency of clones expressing Le(x) with age (P=.021). In this community, expression of Le antigens differs in H. pylori isolates obtained from children versus adults.

Abdominal Pain↗
PubMed2001

Cell vacuolation caused by Vibrio cholerae hemolysin.

Non-O1 strains of Vibrio cholerae implicated in gastroenteritis and diarrhea generally lack virulence determinants such as cholera toxin that are characteristic of epidemic strains; the factors that contribute to their virulence are not understood. Here we report that at least one-third of diarrhea-associated nonepidemic V. cholerae strains from Mexico cause vacuolation of cultured Vero cells. Detailed analyses indicated that this vacuolation was related to that caused by aerolysin, a pore-forming toxin of Aeromonas; it involved primarily the endoplasmic reticulum at early times (approximately 1 to 4 h after exposure), and resulted in formation of large, acidic, endosome-like multivesicular vacuoles (probably autophagosomes) only at late times (approximately 16 h). In contrast to vacuolation caused by Helicobacter pylori VacA protein, that induced by V. cholerae was exacerbated by agents that block vacuolar proton pumping but not by endosome-targeted weak bases. It caused centripetal redistribution of endosomes, reflecting cytoplasmic alkalinization. The gene for V. cholerae vacuolating activity was cloned and was found to correspond to hlyA, the structural gene for hemolysin. HlyA protein is a pore-forming toxin that causes ion leakage and, ultimately, eukaryotic cell lysis. Thus, a distinct form of cell vacuolation precedes cytolysis at low doses of hemolysin. We propose that this vacuolation, in itself, contributes to the virulence of V. cholerae strains, perhaps by perturbing intracellular membrane trafficking or ion exchange in target cells and thereby affecting local intestinal inflammatory or other defense responses.

Adult↗
PubMed1995

The emerging diversity of the electrophoretic types of Vibrio cholerae in the Western Hemisphere.

Since the Latin American cholera epidemic began in 1991, 447 isolates of Vibrio cholerae O1 from the Western Hemisphere have been assayed by multilocus enzyme electrophoresis (MEE) to determine allelic variation among 16 enzyme-encoding genes. Two electrophoretic types (ETs) were identified among toxigenic isolates from Latin America: 323 were ET 4, the ET associated with the Latin American epidemic, and 29 were ET 3. Twenty-three of these ET 3 isolates had a distinctive antimicrobial resistance pattern also seen in isolates imported into the United States from Latin America and Southeast Asia. These resistant isolates had an identical ribotype and nearly identical pulsed-field gel electrophoresis (PFGE) patterns. Most nontoxigenic isolates analyzed were not precursors or descendants of toxigenic epidemic strains. MEE provided a population genetic frame-work for the interpretation of PFGE and ribotype data from the isolates in this study. All three methods identified 2 distinct strains of toxigenic V. cholerae O1 currently epidemic in Latin America.

Asia, Southeastern↗
PubMedDate not supplied

Frequency of identification of cytotoxigenic strains of Escherichia coli in cases of diarrhea from rural and urban communities.

It has been suggested that strains of Escherichia coli producing Vero-Toxin (VTEC) may cause diarrhea or hemorrhagic colitis; however, there are not enough studies to support this hypothesis. We studied the frequency of isolation of VTEC strains in patients with acute diarrhea from rural and urban communities. A total of 1430 strains were analyzed, 361 coming from 118 patients from the rural community (Cadereyta, Qro.) and 1069 from the urban district (D.F.); 95 of these patients were asymptomatic, 213 suffered from watery diarrhea and 43 had bloody diarrhea. For production of toxins, strains were grown in tryptic soy broth for 24h and the culture supernatant was inoculated on HeLa cells; strains were considered cytotoxic when they caused lysis in at least 50% of the cells. In the rural community, VTEC strains were isolated in 20% of the asymptomatics, in 45% of the watery diarrhea patients and in 76% of patients with bloody diarrhea. Frequency of isolation was significantly higher in patients with diarrhea than in asymptomatics (P less than 0.05). The relative risk to present watery diarrhea was 3 and to present bloody diarrhea was 12. In the urban district, VTEC strains were isolated in 13, 7.9 and 4.5% from asymptomatics, watery diarrhea and bloody diarrhea patients, respectively; the relative risk for diarrhea was 1. Colonization by VTEC strains is significantly higher in patients from the rural community and these infected patients have an important risk to develop diarrhea.

Acute Disease↗
PubMedDate not supplied

[Principal serotypes of Salmonella identified in 10703 strains in Mexico from 1982 to 1993].

From 1982 to 1993, 10703 Salmonella strains from The National Network of Diarroheal Laboratories of Mexico were sent to the Enteric Bacteriology Laboratory of INDRE. The strains were confirmed by serology and 119 different Salmonella serotypes were found. The most frequent serotypes were as follows: S. typhimurium, S, enteritidis, S. agona & S. typhi. The strains were classified according to the source of isolation as follows: 6671 strains (62.33%) from clinical samples, mainly of faecal origin; 2903 (27.1%) from food for human consumption; 425 from food for animal consumption, 665 (6.21%) from environment or fomites and 39 (0.36%) from animals. The most frequent serotype in clinical samples was S. typhimurium among 96 different serotypes. The main serotype from blood cultures was S. typhi although 27 other serotypes were found. Of thirteen serotypes related to diarrhoeal outbreaks the higher frequency of S. typhimurium was observed but S. typhi caused more outbreaks. A frequency of 119/> 2000 serotypes was observed, that means less than 5% of Salmonella known serotypes. A yearly variability on serotype predominance was observed as well as changes on source of isolation. This results suggest that epidemiological surveillance of salmonellosis should be continued and improved, looking for cases, asymptomatic carriers and contaminated food for human consumption.

Animal Feed↗
PubMedDate not supplied

[Identification of enterotoxins and cytotoxins of Escherichia coli by Vero cell culture and solid-phase hybridization (colony blot)].

We studied 40 E. coli strains from meat and hamburger and 64 strains from stools of people: 14/64 from traveler's diarrhea and 50/64 from infants with and without diarrhea. We want to know if they could be producing of cytotoxin and enterotoxin in Vero culture cells as well as phenotypic and genotypic relationships. The serotypes that we isolated were different than O:157H:7. We found 3 cytotoxic strains, 77 heat labile enterotoxic strains on Vero culture cells, and 19 E. coli strains with cytotoxin and LT enterotoxin. One strain isolated from infant with diarrhea was negative sorbitol but cytotoxic effect and it was O:55 serotype. The colony blot and cytotonic were found in 90 (86.5%) E. coli strains. The sensitivity of colony blot was 93.75%.

Adult↗
PubMedDate not supplied

[Phenotypic and genotypic characterization of Vibrio cholerae O1].

We made 52180 tests for isolation and identification of toxigenic V. cholerae O1 from rectal swabs and reference strains. We isolated 17.6% V. cholerae O1 strains in 1991, 43.5% in 1992 and 38.9% in 1993. The main serovar in 1991 was Inaba, whereas in 1993 a similar percentage was serovar Ogawa. The phenotype of V. cholerae strains was determined by hemolysis test, Voges-Proskauer test, polymyxin B resistance and phages 4 and 5 resistance. All of the mexican strains were El Tor. There were 2.9-0.75% hemolytic strains from 1991 to 1993, but they were negative when the test was made in tube with human erythrocytes. The resistotypes were performed in 24526 selected strains by Kirby-Bauer method and MIC tests. All of the strains were sensitive, except more than 100 strains isolated in Veracruz that were resistant to tetracycline and doxycycline. Detection of cholera toxin was made by ELISA and on culture of Vero and CHO cells. All the V. cholerae O1 strains were toxigenic. The genotype was determined by PCR and ribotyping. The PCR amplified one 564 pb fragment on V. cholerae O1. The ribotypes of mexican strains were 5 and 6a.

Bacterial Typing Techniques↗
PubMedDate not supplied

[Antibiotic resistance pattern of 24, 526 strains of Vibrio cholerae O1 isolated in Mexico from 1991 to 1993].

Profile of antimicrobial resistance by Kirby-Bauer method was performed on 24526 Vibrio cholerae O1 strains isolated in México (1991-1993) from fecal swabs in cholera cases and from asymptomatic carriers. Minimal inhibitory concentration (MIC) tests for tetracycline (Te) and doxycycline (D) were done on selected strains. Single antibiotic discs were used at concentrations of: Te, 30 micrograms; D, 30 micrograms; erythromycin (E), 15 micrograms; chloramphenicol (CM), 30 micrograms; ampicillin (AM), 10 micrograms; trimethoprim-sulfamethoxazole (SXT) 1.25 micrograms/23.75 micrograms. Strains whose halos were of a smaller diameter than the intermediate value were considered resistant. It is important to maintain surveillance on antimicrobial susceptibility as epidemiological marker on geographical selected areas in order to detect changes of resistant patterns.

Carrier State↗
PubMedDate not supplied

[Cytotonic and cytotoxic effect of cholera toxin on Vero cells and its relation to PCR].

We studied 40 Vibrio cholerae strains: 16 from stool, 16 from sewage and 8 from food. The serotypes were Inaba in 21 strains, 8 Ogawa strains and 11 V. cholerae non-O1. PCR was made with ctx2 and ctx3 primers with 25 cycles of temperature: 1 min at 94 degrees C, 1 min at 60 degrees C and 1 min at 72 degrees C. 24 V. cholerae strains were positive: 18/24 Inaba y 6/24 Ogawa. PCR was negative for 16 strains: 3 Inaba serotype, 2 Ogawa y 11 V. cholerae non-O1. In Vero culture cells 18 strains were cytotonic, 21 cytotoxic and 1 strain was negative. ELISA was positive for 11 strains with PCR positive. The PCR sensitivity was 95.83% compared with culture cells. V. cholerae O1 produced cytotoxic effect on Vero culture cells, maybe related to ACE factor. Colony blot was made with a specific probe labeled with digoxigenin and it could detect 4 Vibrio cholerae toxigenic strains with PCR negative. All V. cholerae Non O1 strains were PCR negative.

Animals↗
PubMedDate not supplied

[Polymerase chain reaction (PCR) for the identification of toxigenic Vibrio cholerae O1 in oysters].

PCR was made with ctx2 (CGG GCA GAT TCT AGA CCT CCT G) y ctx3 (CGA TGA TCT TGG AGC ATT CCC AC) primers for subunit A of cholera toxin, 30 cycles of temperature on samples of 50 g of oysters added in 450 ml of peptone alcaline water that were inoculated with 15 x 10(6), 0.75 x 10(6) and 0.15 x 10(6) CFU/ml of toxigenic 6707 V. cholerae O1 reference strain. The samples were tested by three microbiological methods: INDRE's method uses 1 x 10(-1) dilution of sample, two fold pass to peptone alcaline water pH 9 incubated 18 h and 6 h at 37 degrees C, the Food and Drugs Administration (FDA) method uses 10(-1) to 10(-6) dilutions of sample, 6 h incubation and reincubation for 18 h at 37 and 42 degrees C and the Mexican laboratories (LMD) with 10(-4) to 10(-3) dilutions, the samples were incubated for 6 h and then reincubated for 18 h at two temperatures 37 and 42 degrees C. The PCR by INDRE's method was positive with 3 x 10(2) CFU/ml/g oyster. In the FDA's method the PCR detected DNA in 10(-4) dilution with 3 x 10(1) CFU/ml/g oyster and in LMD's method the PCR was positive in 10(-3) with 3 CFU/ml/g oyster. The results of the PCR were obtained between 5-6 h, and later V. cholerae O1 was isolated by three microbiological methods. The PCR reproducibility was better on DNA sample diluted 1:4 and 10 microliters of sample increased from 1:1000 to 1:10000 the sensitivity of PCR.

Animals↗
PubMedDate not supplied

[Epidemiology and etiology of infectious diarrheas. The case of Mexico].

Gastrointestinal infections represent a health problem. It is estimated that 1647 million cases of diarrhea and 3.2 million deaths due to this cause occur among children less than five years of age per year. Those belonging to this age group have 15 times more risk of dying because of diarrhea. Cases of liquid acute diarrhea with blood represent 80% of cases, diarrhea with blood represent 10%. Most frequent causes of liquid diarrhea are enterotoxigenic Escherichia coli and rotaviruses and most frequent causes of bloody diarrhea are Shigella, E. coli (EHEC and EPEC). Campylobacter jejuni and Entamoeba histolytica. Annually 15,000 cases of typhoid fever are reported that continue being a public health problem. A negative correlation has been observed between the use of oral rehydration and infant mortality due to diarrhea. After prevention and control measures for cholera, a decrease in morbidity and mortality due to diarrhea has been observed. However, to reduce mortality due to this cause, it is necessary to treat the cases of acute dysentery and persistent diarrhea as well as to increase coverage of health care, to standardize the studies of etiology of diarrhea in Mexico, to establish surveillance centers for the study of diarrhea that give information on the distribution, frequency and trends of microbial agents and to achieve standardized microbiological and parasitological studies of etiology of diarrhea that support public health interventions as vaccination and selective administration of antibiotics.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

[Perspectives on cholera vaccines].

Perspectives of cholera vaccines with emphasis in their possible usage in Latin American countries are discussed. Microbiology, antigenicity, relevant aspects of traditional serology, protective immune responses and epidemiological data up to December, 1991, are presented. Indications of parenteral vaccines are discussed. Finally, perspectives of usage of cholera vaccines in Latin America are analyzed.

Adolescent↗