community study ͉ developing country ͉ diarrheal disease ͉ environment ͉ humans

Enteroinvasive Escherichia coli (EIEC) causes dysentery; however, it is less widely reported than other etiological agents in studies of diarrhea worldwide. Between August 2003 and July 2005, stool samples were collected in case-control studies in 22 rural communities in northwestern Ecuador. Infection was assessed by PCR specific for LT and STa genes of enterotoxigenic E. coli (ETEC), the bfp gene of enteropathogenic E. coli (EPEC), and the ipaH gene of both enteroinvasive E. coli and Shigellae. The pathogenic E. coli most frequently identified were EIEC (3.2 cases/100 persons) and Shigellae (1.5 cases/100 persons), followed by ETEC (1.3 cases/100 persons), and EPEC (0.9 case/100 persons). EIEC exhibited similar risk-factor relationships with other pathotypes analyzed but different age-specific infection rates. EIEC was the predominant diarrheagenic bacteria isolated in our community-based study, a unique observation compared with other regions of the world.

The evolution of antibiotic resistance (AR) increases treatment cost and probability of failure, threatening human health worldwide. The relative importance of individual antibiotic use, environmental transmission and rates of introduction of resistant bacteria in explaining community AR patterns is poorly understood. Evaluating their relative importance requires studying a region where they vary. The construction of a new road in a previously roadless area of northern coastal Ecuador provides a valuable natural experiment to study how changes in the social and natural environment affect the epidemiology of resistant Escherichia coli. We conducted seven bi-annual 15 day surveys of AR between 2003 and 2008 in 21 villages. Resistance to both ampicillin and sulphamethoxazole was the most frequently observed profile, based on antibiogram tests of seven antibiotics from 2210 samples. The prevalence of enteric bacteria with this resistance pair in the less remote communities was 80 per cent higher than in more remote communities (OR = 1.8 [1.3, 2.3]). This pattern could not be explained with data on individual antibiotic use. We used a transmission model to help explain this observed discrepancy. The model analysis suggests that both transmission and the rate of introduction of resistant bacteria into communities may contribute to the observed regional scale AR patterns, and that village-level antibiotic use rate determines which of these two factors predominate. While usually conceived as a main effect on individual risk, antibiotic use rate is revealed in this analysis as an effect modifier with regard to community-level risk of resistance.

Diarrheal risk associated with Plesiomonas shigelloides infection was assessed in rural communities in northwestern Ecuador during 2004–2008. We found little evidence that single infection with P. shigelloides is associated with diarrhea but stronger evidence that co-infection with rotavirus causes diarrhea.

Prevalence of this genotype is increasing.

Holm oak trees (Quercus ilex L.) mortality is increasing worryingly in the Mediterranean area in the last years. To a large degree this mortality is caused by the oomycete Phytophthora spp., which is responsible for forest decline and dieback in evergreen oak forest areas of the southwestern Iberian Peninsula. This study is based on the possibility of applying chemical elicitors or filtered oomycete extracts to holm oak somatic embryos (SE) in order to induce epigenetic memory, priming, that may increase tolerance to the pathogen in future infections. To this end, we first examined the effect of priming treatments on SE development and its oxidative stress state, to avoid elicitors that may cause damage to embryogenic tissues. Both, the sterile oomycete extracts and the chemical elicitor methyl jasmonate (MeJA) did not produce any detrimental effect on SE growth and development, unlike the elicitors benzothiadiazole (BTH) and p-aminobenzoic acid (PABA) that reduced the relative weight gain and resulted in necrotic and deformed SE when were applied at high concentrations (25 µM BTH or 50 µM PABA) in accordance with their high malondialdehyde content. No significant differences among elicitation treatments were found in dual culture bioassays, although those SEs elicited with 50 µM MeJA increased H2O2 production after challenged against active oomycete indicating the activation of stress response. Since this elicitation treatment did not produce any adverse effect in the embryogenic process we suggest that could be used in further priming experiments to produce holm oak plants adapted to biotic stress.

Previous studies suggest that the emerging G9P [8] genotype was the most prevalent rotavirus genotype in Ecuador during 2005. This present study provides a temporal analysis of the distribution of rotavirus genotypes in two locations within Ecuador by adding additional years (2006 -early 2008) to the originally reported 2005 data. Data were collected in a rural (northern coastal Ecuador) and urban (Quito) area. In the rural area, a community sample of cases (those presenting diarrhea) and controls (those not presenting diarrhea) were collected between August 2003 and March 2008 resulting in a total of 3,300 stool samples (876 cases and 2,424 controls). Of these samples, 260 were positive for rotavirus by an immunochromatographic test (196 cases and 64 controls). In Quito, 59 fecal samples were collected from children presenting diarrhea and diagnosed with rotavirus. An RT-PCR analysis of samples collected between 2005 and 2007 suggested that G9 was replaced by G1 and G2 in the rural and urban settings. During this period G9 decreased from 79% to 9% while G2 increased from 0% to 43% in the rural communities, and G9 decreased from 79% to 37% while G2 increased from 3% to 57% in the urban area of Quito. This rapid replacement of G9 by G1 and G2 reinforces the necessity of surveillance to inform vaccination programs.

Graphical abstract