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. 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. 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. 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. 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.

Acute diarrheal disease (ADD) is a global public health problem, especially in developing countries and is one of the causes of mortality in children under five. ADD etiologic agents include viruses, bacteria and parasites in that order. Escherichia coli bacteria it is classified as a major diarrheagenic agent and transmitted by consuming contaminated water or undercooked foods. This review compiled updates on information virulence factors and pathogenic mechanisms involved in adhesion and colonization of seven pathotypes of E. coli called enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), shigatoxigenic E. coli (STEC), enteroaggregative E. coli (EAEC) and diffusely-adherent E. coli (DAEC). A final pathotype, adherent-invasive E. coli (AIEC) associated with Crohn's disease was also reviewed. The diarrheagenic pathotypes of E. coli affect different population groups and knowledge of the molecular mechanisms involved in the interaction with the human is important to guide research towards the development of vaccines and new tools for diagnosis and control.

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.

The Ib-M6 peptide has antibacterial activity against non-pathogenic Escherichia coli K-12 strain. The first part of this study determines the antibacterial activity of Ib-M6 against fourteen pathogenic strains of E. coli O157:H7. Susceptibility assay showed that Ib-M6 had values of Minimum Inhibitory Concentration (MIC) lower than streptomycin, used as a reference antibiotic. Moreover, to predict the possible interaction between Ib-M6 and outer membrane components of E. coli, we used molecular docking simulations where FhuA protein and its complex with Lipopolysaccharide (LPS–FhuA) were used as targets of the peptide. FhuA/Ib-M6 complexes had energy values between −39.5 and −40.5 Rosetta Energy Units (REU) and only one hydrogen bond. In contrast, complexes between LPS–FhuA and Ib-M6 displayed energy values between −25.6 and −40.6 REU, and the presence of five possible hydrogen bonds. Hence, the antimicrobial activity of Ib-M6 peptide shown in the experimental assays could be caused by its interaction with the outer membrane of E. coli.

The development of new strategies to reduce the use of traditional antibiotics has been a topic of global interest due to the resistance generated by multiresistant microorganisms, including Escherichia coli, as etiological agents of various diseases. Antimicrobial peptides are presented as an alternative for the treatment of infectious diseases caused by this type of microorganism. The Ib−M1 peptide meets the requirements to be used as an antimicrobial compound. However, it is necessary to use strategies that generate protection and resist the conditions encountered in a biological system. Therefore, in this study, we synthesized alginate and chitosan nanoparticles (Alg−Chi NPs) using the ionic gelation technique, which allows for the crosslinking of polymeric chains arranged in nanostructures by intermolecular interactions that can be either covalent or non-covalent. Such interactions can be achieved through the use of crosslinking agents that facilitate this binding. This technique allows for immobilization of the Ib−M1 peptide to form an Ib−M1/Alg−Chi bioconjugate. SEM, DLS, and FT-IR were used to determine the structural features of the nanoparticles. We evaluated the biological activity against E. coli ATCC 25922 and Vero mammalian cells, as well as the stability at various temperatures, pH, and proteases, of Ib−M1 and Ib−M1/Alg-Chi. The results showed agglomerates of nanoparticles with average sizes of 150 nm; an MIC of 12.5 µM, which was maintained in the bioconjugate; and cytotoxicity values close to 40%. Stability was maintained against pH and temperature; in proteases, it was only evidenced against pepsin in Ib−M1/Alg-Chi. The results are promising with respect to the use of Ib−M1 and Ib−M1/Alg−Chi as possible antimicrobial agents.

Introduction.Acute diarrheal disease (ADD) is a common cause of morbidity and mortality in children under 5 years of age. Understanding of the etiology of ADD is lacking in most low and middle income countries because reference laboratories detectlimited number of pathogens. The objective of this study was to determine the feasibility to conduct a comprehensive case-control study to survey diarrheal pathogens among children with and without moderate-to-severe ADD.Materials and Methods.Microbiology and molecular-based techniques were used to detect viral, bacterial, and parasitic enteropathogens. The study was conducted in Bucaramanga, Colombia, after Institutional Review Board approval was obtained.Results.Ninety children less than 5 years of age were recruited after a written informed consent was obtained from parents or guardians. Forty-five subjects served as cases with ADD and 45 as controls. Thirty-six subjects out of 90 (40.0%) were positive for at least one enteropathogen, that is, 20 (44.4%) cases and 16 (35.5%) controls.Conclusions.The three most common enteric pathogens were enteroaggregativeE. coli(10.0%),Norovirus(6.7%), andSalmonellaspp. (5.6%). TheE. colipathogens were 18.8% of all infections making them the most frequent pathogens. Half of ADD cases were negative for any pathogens.