Helicobacter pylori infection in children: should it be carefully assessed?

The prevalence of H. pylori infection, mainly acquired during childhood and may be persisting throughout life, has been found high in developing countries; this high prevalence is related to low socioeconomic status. The persistence of bacterium exposure is related to gastritis and other severe complications including peptic ulcer, lymphoma MALT and gastric cancer, which are rarely present in the pediatric age due to a lower inflammatory and immunological response. Virulence factors, host gastric mucosal factors, and the natural environment of patients are associated with the clinical outcome of H. pylori infection. The main bacterial virulence factors include adhesins (BabA, SabA), vacuolating cytotoxin VacA, and the products of the cag pathogenicity island (cag PAI). There are geographic differences between cagA, vacA status and H. pylori related diseases. The main criteria to evaluate H. pylori infection in children are gastrointestinal and extra gastrointestinal manifestations related to H. pylori infection, familial history of gastric cancer, peptic ulcer, lymphoma MALT, symptomatic children living in high prevalence regions, and immigrant or adopted children in developed countries. Early detection of H. pylori and its virulence factors, in addition to effective methods of eradication associated with prevention programs, may lead to the decrease of H. pylori incidence and gastritis, especially in endemic high-risk regions. The early assessment in children may prevent further severe complications in adulthood.

Helicobacter pylori en Venezuela: un problema infeccioso multifactorial / Helicobacter pylori in Venezuela: a problem infectious multifactorial

Los objetivos del presente trabajo fueron: establecer la seroprevalencia de la infección por Helicobacter pylori en población venezolana y su asociación con trastornos gastroduodenales y evaluar la presencia del gen cagA mediante la reacción en cadena de la polimerasa y su asociación con trastornos gastroduodenales. Para el estudio de seroprevalencia se evaluaron un total de 1041 personas de distintos estados del país, 370 adultos sintomáticos, 406 asintomáticos, 27 niños sintomáticos y 238 asintomáticos. La determinación de anticuerpos IgG específicos se realizó mediante ELISA comercial. La presencia del gen CagA fue evaluada en 133 pacientes del área metropolitana y el Centro de Cáncer Gástrico de San Cristóbal. Las biopsias se analizaron por diferentes métodos de diagnóstico para H. pylori: cultivo, prueba de ureasa, reacción en cadena de la polimerasa. En la población infantil el porcentaje de niños con valores de anticuerpos IgG específicos anti-H. pylori varía de 30 por ciento a 60 por ciento. En adultos sintomáticos la seroprevalencia varía entre un 68 por ciento a 93 por ciento según el área geográfica estudiada. Una disminución de anticuerpos IgG anti- H. pylori se observó en pacientes con gastritis antral difusa asociada con metaplasia tipo II. En el grupo de pacientes de San Cristóbal se observaron títulos elevados en pacientes con gastritis antral difusa. Un 46 por ciento de las cepas de H. pylori aisladas de pacientes del Area Metropolitana presentaron el gen cagA a diferencia de grupo de San Cristóbal donde se observó una frecuencia menor (26,41 por ciento).

Detection of human papillomaviruses of high oncogenic potential in oral squamous cell carcinoma in a Venezuelan population.

OBJECTIVE: The aim of this work was to detect and typify human papillomaviruses (HPV) in oral squamous cell carcinoma (OSCC) in a Venezuelan population. MATERIAL(S) AND METHODS: Eighteen tissue samples were obtained from biopsies, formalin-fixed, and paraffin-embedded; 16 were diagnosed as SCC. We isolated DNA from paraffin-embedded tissue; two to three sections of 5 microm were obtained and resuspended in digestion buffer and proteinase K. Five microliters of the aqueous phase was used for polymerase chain reaction (PCR). The PCR for HPV amplification was carried out with consensus primers for L1 region (MY09 and MY11) and beta-globin gene was used as internal control. The viral types were determined by molecular hybridization with a mix of probes for high/intermediate and low HPV oncogenic risk types. RESULTS: The HPV-DNA was detected in 50% (eight of 16) of the SCC cases. Of these HPV-DNA-positive samples, 68% were histopathologically diagnosed as moderately differentiated SCC. The most common anatomical location was the alveolar ridge mucosa. All positive biopsies contained high oncogenic HPV types. CONCLUSIONS: We observed a high prevalence of HPV infection of high oncogenic potential types in patients with SCC in our studied group. The moderately differentiated SCCs were more associated to HPV infection. These differences could be influenced by nutritional, environmental and genetical factors in our population but further studies should be carried out to determine these aspects.

Detección del virus papiloma humano en muestras cervicales de una población de estudiantes de la Universidad Central de Venezuela / Detection of the virus papiloma human in a population's of students of the cervical samples Universidad Central de Venezuela

Se hizo detección y tipificación del VPH en 102 estudiantes universitarios que tenían citología o biopsia con cambios relacionados con el virus, mediante la técnica de reacción en cadena de la polimerasa (RCP) e hibridación. La positividad viral hallada fue del 63,7 por ciento con76,9 por ciento de tipos de alto riesgo oncogénito. Un 9,2 por ciento de la población presentó infección mixta de alto y bajo riesgo. En el 18,5 por ciento de las muestras positivas del tipo de VPH fue indeterminado. Los cambios cambios histológicos por VPH sin atípias se hallaron en el 45 por ciento, NIC I en el 20,6 por ciento, NIC II en el 5,9 por ciento, NIC III en el 1 por ciento. A mayor grado histológico se encontró un aumento de muestras positivas para el virus; en cambios sugestivos por VPH fue de 47,8 por ciento, en NIC 180,9 por ciento, en NIC II 83,3 por ciento, y en NIC III 100 por ciento; la misma relación se halló con los porcentajes de genotipos de altos riesgo: cambios sugestivos por VPH 34,7 por ciento; NIC I 57,1 por ciento; NIC II 100 por ciento, NIC III 100 por ciento. La presencia del virus se observó incrementada en los grupos etareos de mayor edad y también con el mayor número de parejas sexuales

Detection of human papillomavirus DNA in benign oral squamous epithelial lesions in Venezuela.

The polymerase chain reaction (PCR) was applied to the detection of human papillomavirus (HPV) infection in biopsies taken from clinically normal oral mucosa of 20 subjects and clinical lesions of 40 patients. PCR for HPV-DNA amplification was performed using consensus primers MYO9/MYO11 and subsequent typing for HPV of high and low oncogenic risk HPV types were identified by restriction enzyme analysis (restriction fragment length polymorphism, RFLP). The HPV viral genome was present in 55% (22/40) of the oral benign lesions (OBL) and in 10% (2/20) of the control samples. In the PCR+ OBL, we observed 90.9% of low oncogenic risk types (HPV-6 -13 and -32) and 9.1% of the samples had a mixed infection with low and high oncogenic types (HPV-6 and -16). In the control samples, we observed one patient with HPV-6 and another with HPV-6 and -16 in the same sample. All of the eight focal epithelial hyperplasia cases were positive for low risk HPV types (88% HPV-13 and 12.5% HPV-32). In conclusion, this study demonstrates a high incidence of HPV in oral benign lesions from Venezuelan patients.

Expression of the multidrug-resistance (MDR) gene in breast cancer.

Of the approximately 18,000 new cases of cancer in Venezuela each year, only half can be treated with surgery and radiation. The remainder must be treated systematically using chemotherapy or biological response modifiers. It has become evident that any drug resistant human tumors express the MDR1 gene, since MDR1 RNA levels are elevated in many cancers that do not respond to chemotherapy. Human mammary carcinomas have multiple oncogene alterations, the most frequently reported being overexpression of the oncogenes c-myc, int-2, neu and c-myb. Thirteen specimens of mammary cancer were obtained by biopsy of untreated patients in stage IIIB. All these patients received three cycles of FAC or CMF-L+GM-CSF after biopsy. In the slot blot analysis of RNA from invasive carcinomas, MDR1 and c-myc transcripts were detectable at a high level in 30% of tumors. Two patients with increased levels of MDR1 before chemotherapy did not respond to the treatment and distant metastasis and death occurred in these patients. Another patient, MDR1-negative before therapy, did not respond to CMF-1 + GM-CSF and showed high levels of MDR1 transcripts in a second biopsy which was obtained during surgery.

[Immunoenzymatic assay for serodiagnosis of Helicobacter pylori infections]. / Ensayo inmunoenzimático para el serodiagnóstico de la infección de Helicobacter pylori.

Enzyme-linked immunosorbent assays (ELISA) have been developed to diagnose H. pylori infection. However, the methods are not standardized. We therefore evaluated the sensitivity of ELISA developed in our laboratory in a study population comprising 38 patients with dyspeptic symptoms and 41 healthy children under 10 years. The assays for immunoglobulin G used a pool of sonicated isolates of H. pylori from five patients with dyspeptic symptoms. Serum levels IgG antibodies to cell sonicates of H. pylori were significantly higher (p < 0.001) in patients with positive culture than in the control group. Cutoff score of 0.231 for positive results was determined with mean + 3ds of the healthy group analyzed. On the basis of this survey, we conclude that a serum dilution of 1:300 and 5 micrograms/ml of antigen, are the optimal condition for rapid screening with high sensitivity of 92% of symptomatic patients for the presence of H. pylori.

Detection of microcin production by pathogenic Escherichia coli isolates from children with acute diarrhoea.

Production of low molecular weight antibiotic substances was detected among pathogenic Escherichia coli isolates from diarrhoeal children's feces during evaluation of a rotavirus vaccine in Caracas city. One of these products, microcin V627a, was partially purified and characterized. Microcin synthesis and immunity system appears not to be plasmid determined and the antibiotic was produced to a high level in minimal medium during the stationary phase. This microcin has many features in common with the mccA15 family.

pUCV11001, an IncH plasmid isolated in a Escherichia coli strain from a healthy child.

Plasmids conferring resistance to potassium tellurite but not to other antimicrobial agents were detected among E. coli multiresistant strains isolated from healthy children during a survey in Caracas. Few of them were autotransferable to E. coli K12 and they were conjugative only at temperatures below 30 degrees C. They also conferred to the host cells resistance to lethal action of colicin B, PacB character. pUCV11001, a prototype, was classified into the incompatibility group HI, subgroup HI2. Presence of these non-antimicrobial resistant IncH plasmids in E. coli from human sources is indicative of their wide distribution among Enterobacteria in nature.

Effect of carbohydrate composition of semi-elemental diets on the nutritional recovery of children with chronic diarrhea.

46 of 74 children with chronic diarrhea of unknown etiology between the ages of 44-627 days were studies. They were assigned, by single randomization, to 3 dietary treatments: a) cow's milk, b) a sucrose- free (SED-S), and c) a sucrose containiNG semi-element diet (SED+S), for 15 days. The authors registered the daily increase of body weight, daily amount of ingested kcal, and the increase of body weight/1000 kcal. The number of days with diarrhea before hospitalization, the age and weight of each child before treatment were recorded and analyzed as covariates. Maltase, sucrase, and lactase activity values were compared before treatment, but were not different among the 3 groups. A significant increase of body weight/1000 kcal ingested was observed in children fed the SED-S diet compared to that observed in children on cow's milk (P=.013 in ANCOVA; P+.053 in RANCOVA), and those fed SED+S (P=.009 in Ancova; p.001 in RANCOVA). The covariates did not have any apparent effect on these results. Only 7 of 24 children receiving cow's milk completed the assigned diet. The carbohydrate composition of the semi-elemental diets proved to be fundamental in the nutritional recovery of these patients.

Effect of three dietary treatments upon the histopathology of jejunal biopsies of children with chronic diarrhea.

Thirty two children with chronic diarrhea of unknown etiology were prospectively investigated in a special hospitalization unit. They were all under 5 percentile for weight/height (NCHS). They had no edema and their age range was between three and eighteen months. The patients were given cow's milk and following the first jejunal biopsy they were fed one of three different diets as their only intake for a period of 15 days. The diets consisted of cow's milk and of two semi-elemental diets with different carbohydrate compositions. A second biopsy was taken at the conclusion of the specific diet. The jejunal biopsies were taken with a Crosby capsule just after the duodenal-jejunal junction and were analyzed by light microscopy. The morphological changes before and after 15 days of dietary treatment were evaluated. The children on semi-elemental diets showed a marked reduction of the number of interepithelial lymphocytes, and of lymphocytes in lamina propria. The infants on cow's milk showed no improvement. Our results suggest that cow's milk could be the cause of the persistent mucosal alterations observed in these infants.

Heterogeneous plasmid population from enterotoxigenic Escherichia coli strains isolated in Venezuelan children with acute diarrhea.

Thirty eight enterotoxigenic Escherichia coli (ETEC) isolated from children with acute diarrhea were analyzed in order to assess the possible associations among enterotoxigenicity, antibiotic resistance and other plasmid-mediated virulence properties such as CoIV, Hly and CFA/I. Eighty four percent of ETEC strains were multiresistant. Twenty strains (52.63%) were able to transfer one or more properties studied and 92.68% of the transconjugants were multiresistant. The simultaneous transfer of genes encoding ST enterotoxin and CoIV, Hly or CFA/I was very low (1.82%). The plasmid analysis revealed the presence of a heterogeneous enterotoxigenic (Ent) plasmid population. Additionally, the existence of a conjugative plasmid of approximately 31 megadaltons (Md) of molecular weight encoding for ST and resistance to ampicillin, kanamycin and streptomycin was found. However, this plasmid was not present in all isolates. These results show a diversity of Ent plasmid population which is probably a consequence of the indiscriminate use of antibiotics and the molecular mechanism of transposition of ST and drug-resistance in the evolution of bacterial strains.

[Serotyping of 27 Cryptococcus neoformans strains isolated in Venezuela]. / Serotipificación de 27 cepas de Cryptococcus neoformans aisladas en Venezuela.

Twenty seven autochtonous isolates of Cryptococcus neoformans from different parts of the country were studied. The analysis indicated the following serotype distribution: 63% Serotype A, 29.6% Serotype B, 3.7% Serotype D and 3.7% belonging to C. neoformans var gattii.

Preliminary characterization of Escherichia coli isolated from pigs with diarrhoea in Venezuela.

The aetiology of neonatal porcine diarrhoea was studied in 15 different herds located in the north-western region of Venezuela. Of 56 strains of Escherichia coli analyzed, 16 (28.6%) were shown to produce heat-stable (STa) enterotoxin, as detected by infant mouse assay. Only four of these STa+ isolates also possessed the K88 pilus antigen, two were 987P+ and none possessed the K99 antigen, leaving 10 STa+ samples in which no pilus antigen was identified. Among the 40 STa negative samples were six K88+ specimens, one K99+, four 987P+, one which reacted as K88+ + K99+ and one K88+ + 987P+. Considering as pathogenic any strain showing at least one of the characters studied, pathogenic E. coli were detected with an overall frequency of 42.9%, being more prevalent during the second week of life. An electrophoretic analysis of the plasmid content of the field isolates of E. coli, revealed the presence of numerous species of extrachromosomal DNA, although no direction association could be made between a particular plasmid and any of the pathogenic characteristics identified. Results of Southern blot analysis indicate that the STa enterotoxin was preferentially encoded within an endemic plasmid of 4.9 Md. Other plasmids present in the E. coli isolates could be related to antibiotic resistance. With the exception of one strain, all E. coli isolates were resistant to more than one of the nine drugs tested; multiresistant E. coli were frequently isolated, including four strains which were resistant to seven antibiotics.

Characterization of rotaviruses isolated from pigs with diarrhoea in Venezuela.

The prevalence of porcine rotavirus infection was studied in 15 different herds located in the north-western region of Venezuela. The presence of rotavirus was studied by direct electron microscopy (EM) and by an enzyme-linked immunosorbent assay (ELISA). From 136 samples analyzed during the six months of the study (September 1983-February 1984), 38 (27.9%) were found to be positive for rotaviruses, with infection more common in animals that were 4-6 weeks old. Atypical rotaviruses were not detected in any of the samples examined. Most rotavirus positive specimens were subgrouped using specific monoclonal antibodies in an ELISA test. The majority of the samples (26 out of 38) were found to exhibit Subgroup I antigenicity. Only two specimens, collected from the same herd in two consecutive months, were found to belong to Subgroup II. To characterize further the circulating rotaviruses, electrophoretic analysis of the RNA genome was performed on samples selected from nine different herds. Great variability in the RNA electropherotypes was observed. No correlation was found between subgroup specificity and the migration of the two smaller segments (Genes 10 and 11), as has been described for human rotaviruses.