Outbreaks of cholera-like diarrhoea caused by enterotoxigenic Escherichia coli in the Brazilian Amazon Rainforest
ABSTRACT The relationship between enteropathogens and severe diarrhoea in the Brazilian Amazon is poorly understood. In 1998, outbreaks of acute diarrhoea clinically diagnosed as cholera occurred in two small villages localized far from the main cholera route in the Brazilian rainforest. PCR was performed on some enteropathogens and heat-labile (LT) and/or heat-stable (STh) toxin genes, the virulence determinants of enterotoxigenic Escherichia coli (ETEC), were detected. Further characterization of ETEC isolates revealed the presence of two clones, one from each outbreak. One presenting serotype O167:H5 harboured LT-I and STh toxin genes and expressed the CS5CS6 colonization factor. The other, a non-typeable serotype, was positive for the LT-I gene and expressed the CS7 colonization factor. The current study demonstrates the importance of molecular diagnosis in regions such as the Amazon basin, where the enormous distances and local support conditions make standard laboratory diagnosis difficult. Here we also show that the mis-identified cholera cases were in fact associated with ETEC strains. This is the first report of ETEC, molecularly characterized as the aetiological agent of severe diarrhoea in children and adults in the Brazilian Amazon Rainforest.
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- "In this study, all Colombian ETEC strains positive for ST were only positive for the STh variant; no ETEC strains positive for STp were identified. Low frequency of STp ETEC strains was also reported among Brazilian, Bolivian, and Chilean ETEC clinical isolates suggesting that STh toxin predominates among Latin American ETECs [33, 46, 47]. "
ABSTRACT: Enterotoxigenic Escherichia coli (ETEC) are major causes of childhood diarrhea in low and middle income countries including Colombia, South America. To understand the diversity of ETEC strains in the region, clinical isolates obtained from northern Colombia children were evaluated for multiple locus sequencing typing, serotyping, classical and nonclassical virulence genes, and antibiotic susceptibility. Among 40 ETEC clinical isolates evaluated, 21 (52.5%) were positive for LT gene, 13 (32.5%) for ST gene, and 6 (15%) for both ST and LT. The most prevalent colonization surface antigens (CS) were CS21 and CFA/I identified in 21 (50%) and 13 (32.5%) isolates, respectively. The eatA, irp2, and fyuA were the most common nonclassical virulence genes present in more than 60% of the isolates. Ampicillin resistance (80% of the strains) was the most frequent phenotype among ETEC strains followed by trimethoprim-sulfamethoxazole resistance (52.5%). Based on multiple locus sequencing typing (MLST), we recognize that 6 clonal groups of ETEC clinical isolates circulate in Colombia. ETEC clinical isolates from children in northern Colombia are highly diverse, yet some isolates circulating in the community belong to well-defined clonal groups that share a unique set of virulence factors, serotypes, and MLST sequence types.BioMed Research International 04/2014; 2014(9):236260. DOI:10.1155/2014/236260 · 3.17 Impact Factor
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ABSTRACT: Tabu search (TS) is a stochastic global optimization algorithm, which has been proved to be efficient in solving various combinatorial optimization problems. In this paper a TS with a new technique restricting the neighbors of the current solution is proposed to solve flow shop scheduling problems. An idea obtained from a simulation study on the adaptive behavior of a fish school is used to determine a parameter necessary for neighborhood construction. In order to obtain a better suboptimal solution in a reasonable computation time, the parameter is determined depending on the characteristics of the job data. The validity of the proposed TS is examined through computer experiments. Comparison of the result is made successfully among the proposed TS, the genetic algorithm, and another TS proposed in our earlier paperSystems, Man, and Cybernetics, 2001 IEEE International Conference on; 02/2001
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ABSTRACT: Cholera continues to occur globally, particularly in sub-Saharan Africa and Asia. Oral cholera vaccines have been developed and have now been used for several years, primarily in traveller populations. The licensure in the European Union of a killed whole cell cholera vaccine combined with the recombinant B subunit of cholera toxin (rCTB-WC) has stimulated interest in protection against cholera. Because of the similarity between cholera toxin and the heat-labile toxin of Escherichia coli, a cause of travellers' diarrhoea, it has been proposed that the rCTB-WC vaccine may be used against travellers' diarrhoea. An analysis of trials of this vaccine against cholera (serotype O1) shows that for 4-6 months it will protect 61-86% of people living in cholera-endemic regions; lower levels of protection continue for 3 years. Protection wanes rapidly in young children. Because the risk of cholera for most travellers is extremely low, vaccination should be considered only for those working in relief or refugee settings or for those who will be travelling in cholera-epidemic areas and who will be unable to obtain prompt medical care. The vaccine can be expected to prevent 7% or less of cases of travellers' diarrhoea and should not be used for this purpose.The Lancet Infectious Diseases 07/2006; 6(6):361-73. DOI:10.1016/S1473-3099(06)70494-7 · 22.43 Impact Factor