Estrategias para prevenir la contaminación microbiana: patógenos alimentarios emergentes / Strategies to prevent microbial contamination: emerging food pathogens

La contaminación de alimentos es un problema mundial que ha motivado a la OMC y al Codex Alimentarius a apoyar nuevas estrategias para asegurar la producción de alimentos seguros para todos. Los procedimientos basados en el análisis de riesgos y control de los puntos críticos (HACCP) constituyen la principal herramienta para el logro de este objetivo. El éxito de este sistema se basa en sólidos conocimientos científicos, y considera no sólo a microorganismos patógenos, sino también a las interacciones microbio-alimentos-huésped. La investigación e información científica es por lo tanto, crucial para el mejoramiento en la seguridad de los alimentos, y para reducir el consumo de alimentos contaminados. No menos de 10 Patógenos Microbianos Emergentes asociados a gastroenteritis y contaminación de alimentos. Estos son, Campylobacter jejuni, Escherichia coli enterohemorragica, Listeria monocytogenes. Arcobacter butzleri, Helicobacter pylori, Criptoporidium parvum, Cyclospora cayetanensis, de la Hepatis A virus Calicivirus and Rotavirus. Se han desarrollado un gran número de tests rápidos para detectar apropiadamente estos patógenos en alimentos contaminados. La mayoría de estos ensayos están basados en técnicas moleculares como PCR, inmunoensayos en fase sólida y otros. Esto implica que si el sistema HACCP va a ser implementado, y por lo tanto la industria de alimentos requerirá de inversiones y de entrenamiento, los laboratorios de microbiología de alimentos deberán establecer metodologías moleculares nuevas y entrenar adecuadamente a su personal. Por último, las agencias gubernamentales de control de alimentos deberán progresar desde un sistema basado en el control del producto final, a un dirigido a la estimación de riesgos y a la prevención. Estos importantes desafíos están aún pendientes en nuestro país

Aplicación de la serología para confirmar la erradicación de helicobacter pylori en pacientes con úlcera péptica / Serological asssessment of helicobacter pylori eradication in peptic ulcer patients

Background: Measurement of changes in serum antibodies is an excellent predictor of Helicobacter pylori eradication after antibiotic treatment. Aim: To measure the changes in serum antibody titers to Helicobacter pylori, before and after treatment. Material and methods: IgG antibodies to H. pylori were prospectively evaluated in 107 duodenal ulcer patients treated either with antibiotics (amoxicillin, metronidazole and bismuth subsalicylate) plus omeprazole or omeprazole alone. IgG antibody levels were determined using an "in house" ELISA in sera from 49 eradicated patients that received quadruple therapy and 58 non-eradicated patients (12 in whom antibiotic therapy failed and 46 that received omeprazole alone). Endoscopy, urease test, microscopy, and culture of gastric biopsies confirmed H. pylori eradication. Results: Patients in whom H. pylori was eradicated, showed a maintained drop in serum antibody titers that ranged from 15 percent, 62 percent, 74 percent to 76 percent at 28 days, 4, 8 and 12 months respectively. Such reduction was not observed in patients treated with omeprazole. Patients, in whom quadruple therapy failed to eradicate H. pylori, showed a discrete and transient decrease in antibody titers. By the fourth month, patients in whom eradication with quadruple therapy was not achieved, irrespective of whether they received quadruple therapy or omeprazole alone. Conclusions: A 45 percent decrease in IgG titer after 4 months is indicative of therapeutic success in H. pylori eradication. Therefore, serology may be useful to monitor the outcome of antibiotic therapy

Estudio prospectivo de erradicación de helicobacter pylori en ulcerosos duodenales: análisis de biopsias de antro y cuerpo gástrico / Prospective study of helicobacter pylori erradication in duodenal ulcer patients: analysis of antral and gastric body biopsies

Omeprazole may not eradicate helicobacter pylori from the stomach but rather displace it from the antrum to the stomach body. This fact could interfere with colonization studies in patients receiving the drug. The aim of this study was to assess the presence of helicobacter pylori, defined as a positive wrease test, culture or microscopical examination, in antral and gastric body biopsies in patients receiving treatment with omeprazole. Sixty four paired antral and gastric body biopsies obtained at the end of a 28 day course of omeprazole, 62 obtained 4 months later, 40 obtained 8 months later and 23 obtained 12 months later were analized. there was a 92 percent concordance between antral and gastric body biopsies for the presence of helicobacter pylori. However, 9 of the samples obtained at 28 days (14 percent) were negative for H. pylori in the antrum but positive in the gastric body. It is concluded that for early assessment of helicobacter pylori eradication after omeprazole treatment, paired biopsies of antral and gastric body are needed

Los hábitos de higiene a nivel familiar y fiebre tifoidea / Family hygiene and typhoid fever

We studied the relation of habits related to the fecal-oral cycle and incidence of typhoid fever in children attendidng to school system for 1 to years and in their families. The goal was to identify a predictor to detect families at risk for typhoid fever. A sample of 80 school-moter dyads, 40 of high and 40 of low socio-economic status was studied. 20 children in each group had had thyphoid fever. Logistic regression analysis allowed to identify dirty edges of the toilet vowl and nail eating habits as highly specific (97%) and sensitive (82%) index of risk. The predictor held both in high and low socio-economic groups and could be used to identify families at risk of developing typhoid fever

Respuesta de anticuerpos IgG en pacientes colonizados por helicobacter pylori / Antibodies to helicobacter pylori in colonized patients with gastric symptoms and in asymptomatic groups

The IgG antibody response specific to Helicobacter pylori was evaluated through ELISA in a group of 92 gastric patients colonized by this bacteria. 74 had gastritis and 19 gastroduodenal ulcer. Three control groups were studied in a similary way: normal adult volunteers (n=17), adults with E coli or S typhi bacteremia (n=30) and normal infants (n = 30). IgG antibody response to H pylori was demonstrated in 98% of colonized patients and 0% of infants. Asymptomatic individuals and those with bacteremia had high rates of antibody response (76 and 90% respectively), although this rate and also the titers of antibody response were significantly lower than that of colonized patients (p < 0.05). ELISA reactive sera from colonized patients and asymptomatic individuals evidenced a similar antibody pattern when tested by blotting. This profile was absent in non reactive sera, including those with high antibody titers to C jejuni. The presence of specific IgG antibodies to H pylory in the majority of colonized gastric patients and asymptomatic adults suggest that this infection is very common in our population

Campylobacter gastro-entéricos: bacteriología, epidemiología y patogenia / Gastro-enteric Campylobacter: bacteriology, epidemiology and pathogenesis

The genus Campylobacter compromises over ten species of Gram negative, curved or S shaped rods. Thermotolerant species (C. jejuni, C. coli and C. Laridis) are recognized as important agentes of human diarrhea, whreas C. fetus subsp. fetus is an apportunistic pathogen and C. pyloridis has been associated with gastritis and gastric ulcer. These bacteria can be isolated don selective media using a microaerobic atmosphere. Termotolerant species grow well at 43-C while the other species do not. Identification methods include morphological, cultural an biochemical test, that correlate well genetic characteristics. Enteric infections with Campylobacter spp. occur by ingestión of contaminated liquid or solid food, and through contact with infected animals. A large number of animal species are recognized as reservoirs of these zoonotic bacteria. Disease can be produced by means of invasiviness of by the production of toxins. Erythromycin is the drug of choice for the treatment of Campylobacter enteric infection. However, they are also susceptible to nitrofurans, chloramphenicol and gentamicin. Despite the great information existing about many aspects of Campylobacter infections, only the joint work of clinicians, epidemiologists and laboratory personnel could provide an oberview of the complex factor involved in the infections by Campylobacter spp