Antibiotic resistance, virulence gene, and molecular profiles of Shiga toxin-producing Escherichia coli (STEC) non-O157 strains isolated from human stool samples, cow stool samples, and beef samples over a period of 2 years in Calcutta, India, were determined. Resistance to one or more antibiotics was observed in 49.2% of the STEC strains, with some of the strains exhibiting multidrug resistance. The dominant combinations of virulence genes present in the strains studied were stx 1 and stx 2 (44.5% of strains) and stx 1 , stx 2 , and hlyA (enterohemorrhagic E. coli hemolysin gene) (19% of strains). Only 6.4% of the STEC strains harbored eae. The diversity of STEC strains from various sources was assessed by random amplification of polymorphic DNA (RAPD). STEC strains that gave identical or nearly similar DNA fingerprints in RAPD-PCR and had similar virulence genotypes were further characterized by pulsed-field gel electrophoresis (PFGE). Identical RAPD and PFGE profiles were observed in four sets of strains, with each set comprising two strains. There was no match in the RAPD and PFGE profiles between strains of STEC isolated from cows and those isolated from humans. It appears that the clones present in bovine sources are not transmitted to humans in the Calcutta setting although these strains showed evolutionary relatedness. Maybe for this reason, STEC has still not become a major problem in India.During the past decade, Shiga toxin-producing Escherichia coli (STEC) has evolved from a clinical novelty to a global public health concern. STEC infections have been reported from over 30 countries and can cause a spectrum of human illness ranging from symptom-free carriage to severe bloody diarrhea and even life-threatening sequelae such as hemolyticuremic syndrome (HUS) (4, 31). STEC is a serologically diverse group of food-borne, zoonotic pathogens, of which the serotype O157:H7 has been epidemiologically significant worldwide because of its notoriety of being associated with lifethreatening disease (18). However, in some geographic areas, non-O157 strains are more commonly isolated from persons with diarrhea or HUS than are O157 STEC strains (40).The ability of STEC to cause serious disease in humans is related to the production of one or more Shiga-like toxins (Stx1, Stx2, or their variants), which inhibits protein synthesis of host cells, thus leading to cell death (26, 27). Additional virulence factors-including the presence of a pathogenicity island designated the locus of enterocyte effacement (LEE) and especially eae, one of the constituent genes of LEE, which is responsible for attaching and effacing lesions (17, 28)-are also shown to be necessary for STEC infection. The large plasmid of STEC O157 carries determinants characteristic for STEC that presumably harbor additional virulence factors:hlyA (the enterohemorrhagic E. coli hemolysin gene), which acts as a pore-forming cytolysin on eukaryotic cells (38); the bifunctional catalase peroxidase (KatP) (6); the etp gene cluster (36); and the secreted serin...

Enteroaggregative Escherichia coli (EAEC) is an important diarrheal enteropathogen defined by aggregative adherence to cultured epithelial cells. We have detected EAEC from 121 (6.6%) of 1,826 hospitalized patients admitted with diarrhea to the Infectious Diseases Hospital in Kolkata, India. Watery diarrhea was recorded significantly (P ‫؍‬ 0.0142) more often in children. The majority of the EAEC isolates were not serotypeable (62%) and showed resistance to five or more antibiotics (76%). We studied different virulence genes and the molecular epidemiology of 121 EAEC isolates recovered from diarrheal patients. A PCR assay for detection of virulence genes, an assay for determination of clump formation in liquid culture, and a HeLa cell adherence assay were carried out to characterize the EAEC isolates. Investigations were also conducted to correlate the virulence gene profiles with diarrheal symptoms and molecular epidemiology by pulsed-field gel electrophoresis (PFGE). Two or more virulence genes were detected in 109 (90.1%) EAEC isolates. In the cluster analysis, some isolates with specific gene profiles and phenotypes formed a group or subcluster. This study highlights the comparative distributions of three fimbrial adhesins and other virulence genes among EAEC isolates. The diverse virulence gene and PFGE profiles, along with the existence of diverse serotypes and antibiograms, suggests that the EAEC isolates are genetically heterogeneous in Kolkata.

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The results suggested that the solid dispersion with selected excipients is a powerful tool to accelerate the dissolution of poorly water-soluble drugs.

Inadequate skin permeability is the main challenge encountered in the transdermal drug delivery and to solve this crisis physical and chemical enhancement techniques are being developed. The aim of the present investigation was to study the combined effect of two such techniques, iontophoresis and esterification, on the transdermal delivery of atenolol. A series of ester prodrugs of atenolol were synthesized, characterized and studied for physicochemical properties and stability. In vitro permeation studies were carried out for atenolol and prodrugs at different donor concentrations (5, 10, and 20 mM) by passive process and iontophoresis (0.5 mA/cm(2)). Evaluation of the physicochemical parameters showed significant increase in lipophilicity and slight reduction in pK value in the ester prodrugs compared to parent drug. Stability studies revealed higher stability at pH 4 than pH 6. Prodrugs significantly enhanced the transdermal flux of atenolol in passive process while in iontophoresis the enhancement ranged from 1.4 to 2.7 fold compared to atenolol. In the prodrug series, permeation rate increased with increase in the length of alkyl side chain up to the addition of 5 carbon units, but thereafter no specific pattern was recorded in both passive and iontophoretic process. The steady state flux was highest in atenolol valerate (1.48 micromol/cm(2) h), which shows the promise of meeting the desired permeation rate (3.0- 31.0 micromol/ h) for maintenance of the therapeutic level in a 70 kg human.

In spite of having a excellent permeation-enhancing and targeted drug release profile, ethosome suffers from limited commercialization. Various challenges regarding their commercialization and product development are also discussed in this review with an objective of acting as a directional route for the researchers.