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Background: Acute gastroenteritis (AGE) is a major cause of morbidity and mortality in children aged less than 5 years in low- and middle-income countries where limited access to potable water, poor sanitation, deficient hygiene, and food product contamination are prevalent. Research on the changing etiology of AGE and associated risk factors in Latin America, including Colombia, is essential to understand the epidemiology of these infections. The primary objectives of this study were to describe etiology of moderate to severe AGE in children less than 5 years of age from Bucaramanga, Colombia, a middle-income country in Latin American, and to identify the presence of emerging E. coli pathotypes., Methodology/principal Findings: This was a prospective, matched for age, case-control study to assess the etiology of moderate to severe AGE in children less than 5 years of age in Bucaramanga, Colombia, South America. We tested for 24 pathogens using locally available diagnostic testing, including stool culture, polymerase chain reaction, microscopy and enzyme-linked immunoassay. Adjusted attributable fractions were calculated to assess the association between AGE and each pathogen in this study population. The study included 861 participants, 431 cases and 430 controls. Enteric pathogens were detected in 71% of cases and in 54% of controls (p = <0.001). Co-infection was identified in 28% of cases and in 14% of controls (p = <0.001). The adjusted attributable fraction showed that Norovirus GII explained 14% (95% CI: 10-18%) of AGE, followed by rotavirus 9.3% (6.4-12%), adenovirus 3% (1-4%), astrovirus 2.9% (0.6-5%), enterotoxigenic Escherichia coli (ETEC) 2.4% (0.4-4%), Cryptosporidium sp. 2% (0.5-4%), Campylobacter sp. 2% (0.2-4%), and Salmonella sp.1.9% (0.3 to 3.5%). Except for Cryptosporidium, all parasite infections were not associated with AGE. Three emergent diarrheagenic E. coli pathotypes were identified in cases (0.7%), including an enteroaggregative/enterotoxigenic E.coli (EAEC/ETEC), an enteroaggregative/enteropathogenic E.coli (EAEC/EPEC), and an emergent enteroinvasive E. coli with a rare O96:H19. No deaths were reported among cases or controls., Conclusions/significance: Norovirus and rotavirus explained the major proportion of moderate to severe AGE in this study. Higher proportion of infection in cases, in the form of single infections or co-infections, showed association with AGE. Three novel E. coli pathotypes were identified among cases in this geographic region., Competing Interests: The authors have no conflicts of interest to disclose.

The development of new antimicrobial peptides has become an attractive alternative to conventional antibiotics due to the increasing rates of microbial drug resistance. Ib-M corresponds to a family of cationic synthetic peptides, 20 amino acids in length, that have shown inhibitory effect against the non-pathogenic strain Escherichia coli K-12. This work evaluated the antimicrobial potential of Ib-M peptides against the pathogenic E. coli O157: H7 using a reference strain and a clinical isolate. The Ib-M peptides showed antibacterial activity against both strains of E. coli O157: H7; the minimum inhibitory concentration of Ib-M peptides ranged from 1.6 to 12.5 μM and the minimum bactericidal concentration ranged from 3.7 to 22.9 μM, being Ib-M1 and Ib-M2 the peptides that presented the highest inhibitory effect. Time-kill kinetics assay showed a reduction of the bacterial population by more than 95% after 4 hours of exposure to 1xMIC of Ib-M1. Low cytotoxicity was observed in VERO cells with 50% cytotoxic concentration in the range from 197.5 to more than 400 μM. All peptides showed a random structure in hydrophilic environments, except Ib-M1, and all of them transitioned to an α-helical structure when the hydrophobicity of the medium was increased. In conclusion, these findings support the in vitro antimicrobial effect of Ib-M peptides against the pathogenic bacteria E. coli O157: H7 and prove to be promising molecules for the development of new therapeutic alternatives., Competing Interests: The authors have declared that no competing interests exist.

Introduction: Chronic hepatitis B virus (HBV) infection is an increasing cause of morbidity and mortality in human immunodeficiency virus (HIV)-infected individuals. HIV-positive patients are commonly co-infected with HBV due to shared routes of transmission., Objectives: Our aim was to determine the risk factors, prevalence, genotypes, and mutations of the Surface S gene of HBV, and occult hepatitis B infection (OBI) among patients infected with HIV in a northeastern Colombian city., Methods: A cross-sectional study was conducted with 275 HIV-positive patients attending an outpatient clinic in Bucaramanga, Colombia during 2009-2010. Blood samples were collected and screened for serological markers of HBV (anti-HBs, anti-HBc and HBsAg) through ELISA assay. Regardless of their serological profile, all samples were tested for the HBV S gene by nested-PCR and HBV genotypes were determined by phylogenetic inference. Clinical records were used to examine demographic, clinical, virological, immunological and antiretroviral therapy (ART) variables of HIV infection., Results: Participants were on average 37±11 years old and 65.1% male. The prevalence of HIV-HBV coinfection was 12% (95%CI 8.4-16.4) of which 3.3% had active HBV infection and 8.7% OBI. The prevalence of HIV-HBV coinfection was associated with AIDS stage and ART treatment. Sequence analysis identified genotype F, subgenotype F3 in 93.8% of patients and genotype A in 6.2% of patients. A C149R mutation, which may have resulted from failure in HBsAg detection, was found in one patient with OBI., Conclusions: The present study found a high prevalence of HIV-HBV coinfection with an incidence of OBI 2.6-fold higher compared to active HBV infection. These findings suggest including HBV DNA testing to detect OBI in addition to screening for HBV serological markers in HIV patients.