Molecular characterization of diarrheagenic Escherichia coli pathotypes: Association of virulent genes, serogroups, and antibiotic resistance among moderate-to-severe diarrhea patients.

BACKGROUND: Diarrheagenic Escherichia coli (DEC) signifies as an important etiological agent of moderate-to-severe diarrhea. This study was primarily focused on molecular identification of DEC pathotypes; their association with serogroups and estimates of resistance profiles against different antibiotics regime. METHODS: Five hundred seventy-two stool specimens from diarrhea patients were investigated for DEC pathotypes. Molecular pathotypes were identified by amplification of virulence genes associated with distinct pathotypes followed by sequencing. Diarrhea is a self-limiting disease, however, severity and persistence of infection suggest antibiotic use. Therefore, AST and MIC were determined against common antibiotic regimen. Correlations between molecular pathotypes and serogroups were analyzed by somatic "O" antigen serotyping. RESULTS: The present findings reveal incidence of DEC as an etiological agent up to a level of 21% among all diarrheal age groups. DEC infection rate was higher in children. Enteropathogenic E. coliEPEC, a molecular pathotype of DEC, was found as a predominant pathotype with highest frequency of 13.7%. Two other molecular pathotypes enterotoxigenic E. coli (ETEC) and enteroaggregative E. coli (EAEC) accounted for 5.7% and 1.3%, respectively for all diarrhea incidences. Serological analysis deciphered somatic antigens O26, O2, and O3 as major serogroups identified among EPEC, ETEC, and EAEC pathotypes, respectively. All DEC pathotypes exhibited high levels of antibiotic resistance except for cotrimoxazole and norfloxacin. CONCLUSION: Comprehensive molecular characterization of DEC pathotypes, their incidence estimates, and antibiogram patterns will help in ascertaining better diagnostic and therapeutic measures in management of diarrheal diseases.

Structural, luminescent and antimicrobial properties of ZnS and CdSe/ZnS quantum dot structures originated by precursors.

ZnS quantum dots (QDs) and their core/shell (CdSe/ZnS) structures were studied for Zn based precursor reactivities. ZnS and CdSe/ZnS QDs were prepared selecting aqueous route and then characterized via XRD, TEM, EDX, PL, RAMAN and FTIR practices. Core/shell nanostructures were synthesized by taking dissimilar precursors for the shell formation. Photoluminescence spectra of prepared QDs corroborate the effectual luminescence. Prepared QDs have large surface area that make them useful alternative as organic antimicrobial agent which are highly irritant and unstable. Study of antimicrobial behavior of QD structures was carried out by disk diffusion method. Antimicrobial study of QDs and their core/shell structures was performed against gram negative and gram positive bacteria, E. coli, A. baumanni and Bacillus subtilis respectively. It is found that elemental composition and size of QDs plays important role in antimicrobial behavior. Prepared QDs are fluorescent and have a key role in complex microbial population studies and identification of bacteria.

Prevalence of rotavirus, norovirus and enterovirus in diarrheal diseases in Himachal Pradesh, India.

Diarrheal diseases are responsible for a significant proportion of mortality and morbidity all around the globe. The contribution of viruses to gastroenteritis incidences in humans is well established. In the present study, we have studied the prevalence of rotavirus, norovirus and enterovirus in Himachal Pradesh, a north Indian state. A total of 287 (111 children and 176 adults) stool samples of gastroenteritis patients were screened for the viruses using RT-PCR method. 34.5 % samples were positive for the viral pathogens of gastroenteritis. Rotavirus was the predominant virus detected in the study with 49.5 and 14.8 % positivity in children and adults, respectively. Enterovirus was present in 5.6 % cases whereas norovirus had least prevalence (1.4 %). Co infection (rotavirus and enterovirus) was witnessed at the prevalence rate of 0.6 %. Among different age groups, the prevalence of studied viruses was highest in the children belonging to the age groups of <5 years. Rotavirus infections were found to be significantly associated with vomiting and trend of higher rates of fever and dehydration was seen in children along with diarrhea. Seasonal distribution shows circulation of diarrheagenic viruses throughout the year. This is the first report of prevalence of various diarrheagenic viruses circulating in this region. The outcome of the study from this cohort provides a baseline data which can be used to design the preventive strategies in the otherwise unexplored state of Himachal Pradesh.

Predominance of unusual rotavirus G1P[6] strain in North India: An evidence from hospitalized children and adult diarrheal patients.

Group A Rotavirus remains the leading cause of gastroenteritis in children and accounts for 0.2 million fatalities each year; out of which, approximately 47,100 deaths occur in India. In adults also, rotavirus is reported to be responsible for diarrhea severe enough to require hospitalizations. India has recently introduced rotavirus vaccine in the Universal Immunization Programme and Himachal Pradesh became the first Indian state to implement this project. This study is an attempt to provide the pre-vaccination data on rotavirus gastroenteritis burden and circulating genotypes in Himachal Pradesh, India. A total of 607 faecal specimens (247 children ≤5years, 50 older children and 310 adults) from hospitalized diarrheal patients from Himachal Pradesh, India were screened for rotavirus using ELISA and RT-PCR. The positive samples were further G/P genotyped using semi-nested PCR. Rotavirus was detected in 25.2% and 28.3% of samples with ELISA and RT-PCR, respectively. In children, rotavirus frequency was significantly high with positivity in 49.0% cases whereas 14.0% adult samples have rotavirus in them. Genotyping of the positive samples revealed predominance of G1 (66.0%) and P[6] (66.7%) genotypes. The most common G and P combination was G1P[6] (62.8%) followed by G1P[8] (16.5%), G9P[6] (7.4%) and G12P[6] (5.0%). Molecular analysis reveals the belonging of P[6] strains in Lineage 1a. This pre-vaccination data on rotavirus prevalence and diversity would be helpful for assessing the affect of vaccination on the disease burden and its comparison with post-vaccination data of circulating genotypes would help in studying the effect on diversity of rotavirus strains possibly due to vaccine selection pressure.