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Biomedical subjects

A Cravioto

Publications and source records attributed to A Cravioto.

64 records · Page 4Linked to original sources
PubMed1981

Production of heat-labile or heat-stable enterotoxins by strains of Escherichia coli belonging to serogroups O44, O114, and O128.

Strains of Escherichia coli which belong to enteropathogenic serogroups usually fail to produce heat-labile or heat-stable enterotoxins. However, 1 of 34 strains of E. coli O44, 9 of 45 strains of E. coli O114, and 18 of 82 strains of E. coli O128 produced heat-labile or heat-stable enterotoxins. Most enterotoxigenic isolates were from tropical or developing countries; all three enterotoxigenic strains isolated in Britain were from patients returned from abroad. Enterotoxigenic strains were of many different flagellar types. Certain enterotoxigenic strains of E. coli O114 and O128 possessed colonization factor antigen I.

Antigens, Bacterial↗
PubMedDate not supplied

Helicobacter pylori and other enteric bacteria in freshwater environments in Mexico City.

BACKGROUND: Helicobacter pylori infection is common in the Mexican population; however, sources, routes, and risk factors for infection as well as mode of transmission remain unclear. METHODS: H. pylori was detected by polymerase chain reaction (PCR) technique in three aquatic systems located in the Mexico City area. In addition, microbiologic cultures and physicochemical parameters were measured. The systems were sampled over an 18-month period (1997-1999), resulting in a total of 212 samples for the different analyses. RESULTS: Twenty-one percent of the samples (16/77) were positive for H. pylori; of these, 42% (5/12) were confirmed for cagA gene detection by PCR hybridization. Microbiologic samples (n = 74) yielded Aeromonas hydrophila, Aeromonas caviae, Aeromonas veronii, and Vibrio fluvialis. In the samples for physicochemical analyses (n = 61), low concentrations of dissolved oxygen were detected and residual chlorine was less than the inactivation dose, both providing conditions for potential survival of H. pylori and other enteric pathogens in these environments. CONCLUSIONS: The results of this study suggest that, in Mexico City, water used for human consumption and irrigation may play an important role as a vehicle in the transmission of H. pylori as well as infection by other known enteric pathogens.

Aeromonas↗
PubMedDate not supplied

[Social implications of physician professional and certification quality].

The paper analyzes the social implications of the professional quality of physicians and of their process of certification. The adequate competencies of physicians are especially relevant in countries that have broad social asymmetries and cultural plurality. This diversity of social and epidemiologic conditions demands a profile of physicians able to work in a wide range of environments and able to achieve the best professional practice, making the best use of the available resources for medical care. Medical competencies and quality of care are interrelated. The process of coupling universal knowledge and local conditions creates a synchronic diversity of professional practices. Medical certification must be viewed as part of the process of diffusion of innovations. The development of a variety of abilities to cope with innovations contributes to the production of a diachronic diversity of medical practices. In the light of continuing quality improvement, it is necessary that certification systems be articulated with both continuing medical education and the accreditation and progress of healthcare institutions. Otherwise, there is the risk of increasing inequality in medical practice that, in the last analysis, blames the victim.

Certification↗
PubMedDate not supplied

Short electropherotype rotaviruses isolated longitudinally from a cohort of Mexican infants.

Stool specimens obtained longitudinally during the first year of life of a cohort of 75 rural infants were tested for the presence of rotavirus with an enzyme-linked immunosorbent assay. Thirty four infants showed the presence of rotaviruses during the first year of life. Only 41% of these episodes were associated with diarrhea. Extraction of rotavirus RNA was still possible in 12 of 34 stool samples, ten of them obtained during episodes of associated-diarrhea. Electropherotyping of these rotavirus showed that nine had a short electropherotype. One diarrheal and two asymptomatic samples had a long electropherotype. Subgrouping the viruses with monoclonal antibodies showed that five of the nine rotaviruses with short electropherotype belonged to subgroup I, and two of the three with long electropherotype belonged to subgroup II. The rest of rotaviruses could not be subgrouped. This study confirms the prevalence of only few rotavirus strains in any defined geographic region over a specific period of time, in this case, a rotavirus with a short electropherotype.

Cohort Studies↗
PubMedDate not supplied

[Haemophilus influenzae b: a review on the determinants of pathogenicity and immune response to the infection].

Haemophilus influenzae is still one of the main causes of diverse invasive diseases in children in México. Epidemiologic data indicate that these processes affect primarily the central nervous system and the respiratory tract. Several factors are involved in the expression of infectious disease by this organism, among them the pathogenic determinants of the parasite and those related with resistance in the host. Occurrence of disease is usually the result of the interaction between these determinants. Knowledge of these pathogenic determinants of the parasite and of factors involved in the immune response of the host have allowed an understanding of the infectious process and have directed research in a least three areas: 1) identification of bacterial membrane fractions related with diagnosis of the disease, 2) screening for immunogenic components in the bacterias as vaccine candidates to be used in the prevention of the disease and, 3) the planning of appropriate alternatives for specific antimicrobial therapy.

Bacterial Vaccines↗
PubMedDate not supplied

[Presence of specific factors in mother's milk against strains of diarrhea-causing Escherichia coli in humans].

Presence of specific secretory immunoglobulin A (sIgA) against pathogenic factors of Escherichia coli related with diarrheal disease was studied in colostrum and breast-milk samples obtained longitudinally from a cohort of rural Mexican women. Levels of sIgA against heat-labile enterotoxin, Shiga-like toxin, colonization factors antigens I, II and E8775 and adherence to HEp-2 cells were detected in samples obtained from 54 rural women during the first year of lactation. Although production of specific sIgA against these pathogenic factors was almost universal it was not constant, even in the same woman. The results reflect a definite mother-infant relationship during this period. The data support the thesis of using breast-milk as a vaccination vehicle against diarrhea associated with specific organisms during the first year of life of infants born in developing areas of the world.

Antigens, Bacterial↗
PubMedDate not supplied

[Infections caused by enteropathogenic Escherichia coli].

Escherichia coli strains currently recognized to cause human diarrhea can be distinguished on the basis of pathogenic mechanism and separated into five categories: enterotoxigenic (ETEC), enteroinvasive (EIEC), enterohemorrhagic (EHEC), enteroaggregative (EAggEC) and enteropathogenic (EPEC). EPEC is a bacterial pathogen that causes diarrhea in infants, particularly in developing countries. The purpose of this review is to summarize recent advances in the understanding of EPEC pathogenesis and the contribution of Mexican investigators to the knowledge of this pathogen.

Bacterial Vaccines↗