Maximizing protection from use of oral cholera vaccines in developing country settings: an immunological review of oral cholera vaccines.

Desai, Sachin N,Cravioto, Alejandro,Sur, Dipika,Kanungo, Suman Landes Bioscience 2014 Human Vaccines & Immunotherapeutics Vol.10 No.6

<P>When oral vaccines are administered to children in lower- and middle-income countries, they do not induce the same immune responses as they do in developed countries. Although not completely understood, reasons for this finding include maternal antibody interference, mucosal pathology secondary to infection, malnutrition, enteropathy, and previous exposure to the organism (or related organisms). Young children experience a high burden of cholera infection, which can lead to severe acute dehydrating diarrhea and substantial mortality and morbidity. Oral cholera vaccines show variations in their duration of protection and efficacy between children and adults. Evaluating innate and memory immune response is necessary to understand V. cholerae immunity and to improve current cholera vaccine candidates, especially in young children. Further research on the benefits of supplementary interventions and delivery schedules may also improve immunization strategies.</P>

Diversity in the composition of the accessory genome of Mexican Pseudomonas aeruginosa strains

Luis F. Espinosa-Camacho,Gabriela Delgado,Alejandro Cravioto,Rosario Morales-Espinosa 한국유전학회 2022 Genes & Genomics Vol.44 No.1

Background: Pseudomonas aeruginosa is an important opportunistic pathogen especially in nosocomial infections due to its easy adaptation to different environments; this characteristic is due to the great genetic diversity that presents its genome. In addition, it is considered a pathogen of critical priority due to the high antimicrobial resistance. Objectives: The aim of this study was to characterize the mobile genetic elements present in the chromosome of six Mexican P. aeruginosa strains isolated from adults with pneumonia and children with bacteremia. Methods: The genomic DNA of six P. aeruginosa strains were isolated and sequenced using PacBio RS-II platform. They were annotated using Prokaryotic Genome Annotation Pipeline and manually curated and analyzed for the presence of mobile genetic elements, antibiotic resistances genes, efflux pumps and virulence factors using several bioinformatics programs and databases. Results: The global analysis of the strains chromosomes showed a novel chromosomal rearrangement in two strains, possibly mediated by subsequent recombination and inversion events. They have a high content of mobile genetic elements: 21 genomic islands, four new islets, four different integrative conjugative elements, 28 different prophages, one CRISPR-Cas arrangements, and one class 1 integron. The acquisition of antimicrobials resistance genes into these elements are in concordance with their phenotype of multi-drug resistance. Conclusion: The accessory genome increased the ability of the strains to adapt or survive to the hospital environment, promote genomic plasticity and chromosomal rearrangements, which may affect the expression or functionality of the gene and might influence the clinical outcome, having an impact on the treatment.

Treating diarrhoeal disease in children under five: the global picture

Unger, Carla Chan,Salam, Shumona Sharmin,Sarker, Md Shafiqul Alam,Black, Robert,Cravioto, Alejandro,Arifeen, Shams El BMJ Publishing Group Ltd 2014 Archives of disease in childhood Vol.99 No.3

<P>Rates of childhood mortality due to diarrhoea remain unacceptably high and call for renewed global focus and commitment. Affordable, simple and effective diarrhoeal treatments have already been available for many years, yet a shift in international health priorities has seen coverage of recommended treatments slow to a near-standstill since 1995. This article reviews coverage of recommended childhood diarrhoeal treatments (low-osmolarity oral rehydration solution (ORS) and zinc), globally and regionally, and provides an overview of the major barriers to wide-scale coverage. It is argued that to ensure smooth supply and equitable distribution of ORS and zinc, adequate financing, relevant policy changes, strong public, private and non-government organisation (NGO) collaboration, local manufacturing of pharmaceuticals, mass media awareness and campaigning, in conjunction with strong government support, are necessary for successful treatment scale-up.</P>

Shift in Phenotypic Characteristics of Enterotoxigenic <i>Escherichia coli</i> (ETEC) Isolated from Diarrheal Patients in Bangladesh

Begum, Yasmin Ara,Baby, Nabilah Ibnat,Faruque, Abu S. G.,Jahan, Nusrat,Cravioto, Alejandro,Svennerholm, Ann-Mari,Qadri, Firdausi Public Library of Science 2014 PLoS neglected tropical diseases Vol.8 No.7

<▼1><P><B>Background</B></P><P>Enterotoxigenic <I>Escherichia coli</I> (ETEC) is one of the most common causes of bacterial diarrhea. Over the last decade, from 1996 to 2012, changes in the virulence antigen properties of ETEC such as heat labile (LT) and heat stable (ST) toxins, colonization factors (CFs), and ‘O’-serogroups have been observed. The aim of this prospective study was to compare changes in antigenic profiles of ETEC strains isolated from a 2% surveillance system at the icddr,b hospital in Dhaka, Bangladesh between 2007–2012 and an earlier time period of 1996–1998 conducted at the same surveillance site.</P><P><B>Methodology</B></P><P>In the surveillance system every 50<SUP>th</SUP> patient attending the hospital was screened for major enteric pathogens including ETEC, <I>Vibrio cholerae</I>, <I>Shigella</I> spp. and <I>Salmonella</I> spp. from January 2007 to December 2012.</P><P><B>Principal Findings</B></P><P>Of the 15,152 diarrheal specimens tested between 2007–2012, the overall rate of ETEC isolation was 11%; of these, 43% were LT/ST, 27% LT and 30% ST positive. Isolation rate of ST-ETEC (p<0.009) and LT/ST ETEC (p<0.011) during 2007–2012 period differed significantly compared to those seen between 1996–1998. In comparison to the 1996–1998 period, difference in CF profile of ETEC isolates during 2007–2012 was observed particularly for strains expressing CS7 (12.4%), CS14 (9.5%) and CS17 (10.0%). The predominant CF types were CS5+CS6, CFA/I, CS7, CS17, CS1+CS3, CS6 and CS14. The most common serogroups among the CF positive ETEC isolates were O115, O114, O6, O25 and O8. A strong association was found between CFs and ‘O’ serogroups i.e. between CS5+CS6 and (O115 and O126); CS7 and (O114), CFA/I and (O78 and O126), CS17 and (O8 and O167) and CS1/CS2+CS3 and (O6).</P><P><B>Conclusion</B></P><P>The analyses show a shift in prevalence of antigenic types of ETEC over the study period; the information is important in designing effective ETEC vaccines with broad protective coverage.</P></▼1><▼2><P><B>Author Summary</B></P><P>Diarrheal diseases constitute a major health problem in Bangladesh, where <I>Vibrio cholerae</I> and enterotoxigenic <I>Escherichia coli</I> (ETEC) are two most important causes of bacterial diarrhea. Prevention through vaccination is helpful to reduce the incidence and severity of diarrheal disease due to ETEC, particularly among children in low-resource settings. In this context, we collected stool and/or rectal swab (RS) specimens from patients with diarrhea between 2007 to 2012 under the 2% systematic routine surveillance system at the icddr,b hospital in Dhaka, Bangladesh and screened for ETEC infection. We tested the specimens for two major virulence factors of ETEC: toxins and colonization factors. In this research article, we have focused on changes in toxin as well as colonization factor profiles of ETEC strains isolated from diarrheal patients seeking care at the icddr,b hospital between 2007–2012 and an earlier time period of 1996–1998. We concluded that, such shift in antigenic profile of ETEC over the study period is important in designing effective ETEC vaccines with broad protective coverage.</P></▼2>

Type three secretion system in non-toxigenic <i>Vibrio cholerae</i> O1, Mexico

Mahmud, Jamil,Rashed, Shah M.,Islam, Tarequl,Islam, Saiful,Watanabe, Haruo,Cravioto, Alejandro,Alam, Munirul Lippincott Williams Wilkins 2014 Journal of medical microbiology Vol.63 No.12