Incidence of severe diarrhoea due to Vibrio cholerae in the catchment area of six surveillance hospitals in Bangladesh.

Cholera is an important public health problem in Bangladesh. Interventions to prevent cholera depend on their cost-effectiveness which in turn depends on cholera incidence. Hospital-based diarrhoeal disease surveillance has been ongoing in six Bangladeshi hospitals where a systematic proportion of patients admitted with diarrhoea were enrolled and tested for Vibrio cholerae. However, incidence calculation using only hospital data underestimates the real disease burden because many ill persons seek treatment elsewhere. We conducted a healthcare utilization survey in the catchment areas of surveillance hospitals to estimate the proportion of severe diarrhoeal cases that were admitted to surveillance hospitals and estimated the population-based incidence of severe diarrhoea due to V. cholerae by combining both hospital surveillance and catchment area survey data. The estimated incidence of severe diarrhoea due to cholera ranged from 0.3 to 4.9/1000 population in the catchment area of surveillance hospitals. In children aged <5 years, incidence ranged from 1.0 to 11.0/1000 children. Diarrhoeal deaths were most common in the Chhatak Hospital's catchment area (18.5/100 000 population). This study provides a credible estimate of the incidence of severe diarrhoea due to cholera in Bangladesh, which can be used to assess the cost-effectiveness of cholera prevention activities.

Emergence of multidrug-resistant NDM-1-producing Gram-negative bacteria in Bangladesh.

The main objective of this study was to investigate the prevalence of bla (NDM-1) in Gram-negative bacteria in Bangladesh. In October 2010 at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) laboratories, 1,816 consecutive clinical samples were tested for imipenem-resistant Gram-negative organisms. Imipenem-resistant isolates were tested for the bla (NDM-1) gene. Among 403 isolates, 14 (3.5 %) were positive for bla (NDM-1), and the predominant species were Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli. All bla (NDM-1)-positive isolates were resistant to multiple antibiotics. Among ß-lactamase genes, bla (CTX-M-1-group) was detected in ten isolates (eight bla (CTX-M-15)), bla (OXA-1-group) in six, bla (TEM) in nine, bla (SHV) in seven, and bla (VIM) and bla (CMY) in two isolates each. The 16S rRNA methylase gene, armA, was detected in five K. pneumoniae isolates and in one E. coli isolate. rmtB and rmtC were detected in a Citrobacter freundii and two K. pneumoniae isolates, respectively. qnr genes were detected in two K. pneumoniae isolates (one qnrB and one qnrS) and in an E. coli isolate (qnrA). Transferable plasmids (60-100 MDa) carrying bla (NDM-1) were detected in 7 of the 11 plasmid-containing isolates. Pulsed-field gel electrophoresis (PFGE) analysis grouped K. pneumoniae isolates into three clusters, while E. coli isolates differed significantly from each other. This study reports that approximately 3.5 % of Gram-negative clinical isolates in Bangladesh are NDM-1-producing.

Genetic characterization of Vibrio cholerae O1 strains isolated in Zambia during 1996-2004 possessing the unique VSP-II region of El Tor variant.

New variants of Vibrio cholerae O1 have appeared in different time-frames in various endemic regions, especially in Asia and Africa. Sixty-nine strains of V. cholerae O1 isolated in Zambia between 1996 and 2004 were investigated by various genotypic techniques to determine the lineage of virulence signatures and clonality. All strains were positive for Vibrio seventh pandemic Islands (VSP)-I and VSP-II and repeat toxin (RTX) gene clusters attesting their El Tor lineage. Interestingly, strains isolated in recent times (2003-2004) were identified as an altered variant (El Tor biotype that harbours El Tor type rstR but produce classical ctxB) that replaced completely the progenitor El Tor strains prevalent in 1996-1997. Recent altered variant strains differed from prototype El Tor strains isolated earlier in that these strains lacked two ORFs, VC0493 and VC0498, in the VSP-II region. PFGE analysis revealed two major clonal lineages in the strains; cluster A represented the strains isolated before 2003 and cluster B the altered strains isolated in 2003-2004. Cluster A was closely related to prototype El Tor reference strain isolated in Bangladesh in 1971. Cluster B was found to be matched with Bangladeshi altered strains but was different from the hybrid strains isolated from Mozambique and Bangladesh. This report provides important information on the genesis of altered strains of V. cholerae O1 isolated in Zambia and emphasizes the need for further studies to follow the trends of evolutionary changes.

Helicobacter pylori in the oral cavity is associated with gastroesophageal disease.

BACKGROUND: In Mexico, more than 80% of the population is infected with Helicobacter pylori. The frequency of H. pylori detection in the oral cavity is unknown, as its relationship with gastroesophageal pathology. AIM: To detect the presence of H. pylori in the oral cavity in Mexican population by PCR and to determine its association with gastroesophageal disease. METHODS: Patients were divided into two groups with different clinic conditions from whom gastric biopsy, dental plaque, and saliva samples were taken and analyzed. The first group comprised of hospitalized patients, the majority of whom were diagnosed with gastroesophageal disease, while the second group was selected from a dental clinic (ambulatory population) the majority of whom appeared to be healthy subjects. RESULTS: H. pylori was detected in gastric biopsy, dental plaque and saliva samples by PCR using a set of specific primers for the signal sequence of the vacuolating cytotoxin gene; detection of H. pylori in general was higher in gastric biopsy and dental plaque samples than in saliva samples. Detection of H. pylori in the oral cavity is significantly (P = 0.0001) associated with patients presenting gastroesophageal disease, while healthy subjects and those with other non-gastric disease do not present with H. pylori in their oral cavity. CONCLUSIONS: H. pylori detection in the oral cavity is associated to gastroesophageal disease. In addition, it is suggested that all patients presenting gastric symptoms and H. pylori detection in the oral cavity would begin bacterial treatment immediately.

Effects of gonadotrophin-releasing hormone, recombinant human activin-A and sex steroid hormones upon the follicle-stimulating isohormones secreted by rat anterior pituitary cells in culture.

FSH is produced and secreted from the anterior pituitary gland of rats in multiple molecular forms. At times of high gonadotrophin-releasing hormone (GnRH) and oestrogen output (e.g. the morning of the day of pro-oestrus) the pituitary increases the production of FSH isoforms with isoelectric point (pI) values greater than 5.0, whilst sex steroid deprivation leads to the production of strongly acidic and less in-vitro biologically active FSH molecules. It is not known, however, whether sex steroids modulate the production of specific FSH isoforms by a direct action at the pituitary level or indirectly through altering the rate of synthesis and/or secretion of GnRH. In order to obtain some insight on this issue, we examined the charge heterogeneity of FSH secreted by cultured pituitary cells exposed to different FSH-releasing factors, oestradiol-17 beta and progesterone, alone or in different time-sequenced combinations. Anterior pituitary glands from 21-day-old female rats were enzymatically dispersed into a single cell suspension and cultured for 5 days. During days 1 to 3, cells were incubated in the absence of factors or steroid hormones; on days 3 to 4, cells were incubated in the absence (controls) or presence of either oestradiol-17 beta (3.67 nmol/l) or oestradiol-17 beta plus progesterone (3.67 and 31.8 nmol/l respectively). Finally, during days 4 to 6, GnRH (10 nmol/l) or recombinant human activin-A (2 nmol/l) were added to half of all culture wells. Media from each cell group were concentrated and the several forms of secreted FSH were then separated by polyacrylamide gel isoelectric focusing (pH range 6.5-4.0) and quantitated. All media concentrates contained several forms of immunoactive secreted FSH focusing within a pH range of 6.44-4.23. A large amount (51-76%) of total FSH recovered focused within a pI range of 4.9-4.0 (area 3), whilst 20-43% and 4-8% of the total were identified within pI range of 5.9-5.0 (area 2) and 6.5-6.0 (area 1) respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparative viral frequency in Mexican children under 5 years of age with and without upper respiratory symptoms.

In Mexico, there is a lack of up-to-date published data that show viruses to be the main cause of acute respiratory infection (ARI). The objective of this study was to estimate the comparative viral frequency between children under the age of 5 years with and without ARI (n = 179 in each group) in a suburban community (Nezahualcóyotl City). A nasopharyngeal sample was collected for viral culture and identification was carried out by indirect immunofluorescence (IIF) using mAbs. There were no sex differences between the two groups. Children under 1 year of age with ARI showed a higher frequency (56 %) of viral infections; this was statistically significant (P < 0.05) when compared with the same age group in ARI-free children (17 %). Respiratory syncytial virus (RSV) was the most prevalent type of virus isolated from both groups (38 vs 18 %). A statistically significantly higher number of subjects with ARI (33/179) than without (12/179) were infected with RSV (P < 0.003). Prevalences of four other viruses studied were similar in the two groups. The highest viral incidence of ARI in children was detected in the winter-spring seasonal period.

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.

Survival and characterization of Escherichia coli strains in a typical Mexican acid-fermented food.

In this study, the presence and pathogenic characteristics of Escherichia coli strains in pozol, an acid-fermented maize beverage consumed in South-eastern Mexico, were determined. Seventy-three E. coli strains were isolated at early and late times (6 and 48 h) during the pozol fermentation process, when pH values of the doughs were 6.7-4.7 (6 h) and 4.7-3.7 (48 h). Serotypes that belong to diarrheagenic E. coli serogroups O18, O88, O8, O11, O20, O173 were identified. HEp-2 cell adherence in vitro assays showed localized, diffuse and aggregative adherence patterns among some of these strains. A DNA colony hybridization analysis with different probes showed the presence of virulence genes related to diarrheal pathogenesis. Thirty-three percent of the E. coli strains were tetracycline-resistant and 95% had a 20 kb plasmid. The presence and survival of potentially pathogenic E. coli in acid-fermented pozol suggest that such foods may be a potential source of foodborne outbreaks.

[Presence of specific factors in mother's milk against strains of diarrhea-causing Escherichia coli in humans]. / Presencia de factores específicos en leche materna contra cepas de Escherichia coli causantes de diarrea en humanos.

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.

[Social implications of physician professional and certification quality]. / Implicaciones sociales de la calidad profesional de los médicos y de la certificación.

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.

[Infections caused by enteropathogenic Escherichia coli]. / Infecciones por Escherichia coli enteropatógena.

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.

A novel and simple mixture as point-of-use water treatment agent to produce safe drinking water.

BACKGROUND: People in rural Bangladesh have a poor understanding of the link between use of contaminated surface water and disease. An inexpensive point-of-use water treatment agent was developed to purify surface water. METHODS: Surface water was collected from various sources in Bangladesh from February 2007 to January 2008. Microbiological and physicochemical parameters of raw and treated surface water were analysed. Water was treated with a mixture of alum potash, bleaching powder and lime, or with each agent individually. RESULTS: Raw water was contaminated with bacteria, the counts for total coliforms, faecal coliforms and faecal streptococci being 26,431, 14,548 and 240 colony-forming units (cfu) 100 ml(-1), respectively. These counts fell to 0 cfu 100 ml(-1) after treatment with the mixture. The count of artificially introduced Vibrio cholerae was also reduced to 0 cfu 100 ml(-1) after treatment. Treatment of raw water altered the pH from 6.90 to 6.87, turbidity from 21.61 to 3.55 nephelometric turbidity units (NTU), residual chlorine from 0 to 0.09 mg litre(-1), conductivity from 124.03 to 229.96 µS cm(-1), and total dissolved solids from 59.40 to 199.25 mg litre(-1). All these results of treatment were within the range recommended by the WHO as acceptable for drinking water. CONCLUSION: The mixture of alum potash, bleaching powder and lime described can be safely used to disinfect contaminated surface water to make it suitable for drinking and other household purposes in Bangladesh.

Microbiological quality of complementary foods and its association with diarrhoeal morbidity and nutritional status of Bangladeshi children.

BACKGROUND/OBJECTIVES: To examine the bacteriological quality of complementary foods (CF) and to correlate the results with diarrhoeal morbidity and nutritional status of Bangladeshi children aged 6-24 months. SUBJECTS/METHODS: A total of 212 CF samples were tested, of which 72 were collected immediately before the first time of feeding (≤ 1 h of food preparation) and 140 were collected at second/third time of feeding from 140 households located in urban and rural areas of Bangladesh. Anthropometry, food frequency data and demographic information of the children were collected. RESULTS: Of the first time feeding samples, 3% from each of urban and rural areas were found to be contaminated with faecal coliforms (FC) at ≥ 100 CFU/g. E. coli was isolated from 11% and 6% of samples, and B. cereus from 8% and 6% of samples from urban and rural areas, respectively. In contrast, 33% of the second/third time feeding samples from urban areas and 19% from rural areas were contaminated with FC at ≥ 100 CFU/g (P<0.05). E. coli was isolated from 40% and 39% of samples, and B. cereus from 33% and 26% of samples from urban and rural areas, respectively. Significantly high numbers of wasted rural children had CF with a high aerobic plate count, which was also significantly associated with diarrhoeal morbidity in children. CONCLUSIONS: Around 40% of CF samples were contaminated with E. coli, which was mainly attributable to food preparation practices. Consumption of contaminated CF appeared to be associated with a higher frequency of diarrhoea and malnutrition in children.

Evaluation of a probiotics, Bifidobacterium breve BBG-01, for enhancement of immunogenicity of an oral inactivated cholera vaccine and safety: a randomized, double-blind, placebo-controlled trial in Bangladeshi children under 5 years of age.

To evaluate the probiotic, Bifidobacterium breve strain Yakult (BBG-01), for safety and enhancement of immunogenicity in an oral inactivated cholera vaccine, a randomized double-blind placebo-controlled study was performed. Bangladeshi children under 5-year-old received BBG-01 or placebo for 4 weeks with two doses of oral cholera vaccine. Serum/fecal antibodies and fecal bacterial flora in the study participants were monitored. All adverse events were mild and transient and had no significant difference between the two groups. Immunological responses were similar comparing the two groups. A negative correlation between Bifidobacterium and Enterobacteriaceae in the probiotic group suggests a possible involvement of BBG-01 in alteration of the enteric bacterial flora. In conclusion, BBG-01 is well tolerated by Bangladeshi children although the post vaccinal immunostimulatory effect of BBG-01 was not evident.