Formulation and Evaluation of Chitosan Beads of Levocetirizine Dihydrochloride.

Our study aims to design a controlled drug delivery system for Levocetirizine dihydrochloride by using chitosan beads. The beads were prepared by ionotropic gelation process, with Sodium tri poly phosphate (TPP) as an ionic agent. The formed beads were then further crosslinked using glutaraldehyde and the excess glutaraldehyde were then washed. The physical properties of the prepared beads such as beads sizes, shapes, encapsulation efficiencies, invitro release and degree of swelling were determined. The produced beads from all batches showed a very good spherical geometry with the bead size found to be less than 2mm. The drug loading efficiency was around 77.5% for all batches. The degree of swelling was found to be 1.4. FTIR, DSC and XRD studies shows the absence of the interaction between chitosan and the drug. This methodology of preparation of chitosan beads seems to be highly simple, commercially viable and a promising technique for controlling the release of drugs.

Antimicrobial resistance in Shigella - rapid increase & widening of spectrum in Andaman Islands, India.

Background & objectives: Shigellosis is known to be a major cause of acute childhood diarrhoea in Andaman & Nicobar Islands, India. Rapid emergence of antibiotic resistance warrants continuous monitoring of sensitivity pattern of bacterial isolates. We report here the salient findings of an ongoing study on shigellosis in Andaman Islands, India, with regards to change in drug resistance pattern during the past one decade. Method: During 2006-2009, stools samples from 412 paediatric diarrhoea patients were collected and processed for isolation and identification of Shigella spp. Susceptibility to 22 antimicrobial drugs was tested and MICs were determined for 3rd generation cephalosporins, quinolones, amoxicillin-clavulanic acid combination and gentamicin. Drug susceptibility pattern of these isolates were compared with that of 33 isolates obtained during 2000-2002. Results: Shigella isolates were recovered from 50 of 412 stool samples processed. Resistance to ampicillin, nalidixic acid, tetracycline and ciprofloxacin was observed in 100, 96, 94 and 82 per cent of the isolates, respectively. The frequency of resistance to these drugs was significantly (P<0.001) higher than that observed during 2000-2002. Resistance to seven drugs was observed in 2000-2002, whereas resistance to 21 drugs was seen during 2006-2009. The number of drug resistance pattern increased from 13 in 2000-2002 to 43 in 2006-2009. Resistance to newer generation fluoroquinolones, 3rd generation cephalosporins and augmentin, which was not observed during 2000-2002, appeared during 2006-2009. Interpretation & conclusions: The frequency of resistance among Shigella isolates has increased substantially between 2000-2002 and 2006-2009 and the spectrum of resistance has widened. At present, the option for antimicrobial therapy in shigellosis in Andaman is limited to a small number of drugs. Continuous local monitoring of resistance patterns is necessary for the appropriate selection of empirical antimicrobial therapy.

Survivability of Shigella dysenteriae type 1 & S. flexneri 2a in laboratory conditions simulating aquatic environment.

BACKGROUND & OBJECTIVES: Information about the duration of survival of Shigellae in water is speculative. The present study was undertaken to assess the duration of survival of Shigella dysenteriae type 1 and S. flexneri type 2a in the laboratory conditions simulating the aquatic environment, their invasive property and the association of different physico-chemical parameters in the survival process. METHODS: Five natural water sources were selected in a diarrhoea prone rural area. Collection of water, determination of physico-chemical parameters and bacteriology were carried out following standard procedures. Filter-sterilised water samples were inoculated with S. dysenteriae type 1 and S. flexneri 2a and survival was monitored by estimating total viable count at regular intervals. Bivariate correlations between the duration of survival and physico-chemical parameters were estimated. Multiple linear regression models were fitted for the duration of survival of the bacteria. RESULTS: All water sources were contaminated with faecal coliforms including Escherichia coli, S. dysenteriae type 1 survived for a mean duration of 3.33 days and S. flexneri 2a for mean 11.167 days in field water samples in laboratory condition. Duration of survival had positive correlation with the initial bacterial counts. In the multiple regression model the strongest predictor of the duration of survival of both S. dysenteriae type 1 and S. flexneri 2a was the concentration of bacteria. Other possible predictors for S. flexneri 2a were Mg and water temperature. INTERPRETATION & CONCLUSION: S. dysenteriae type 1 with epidemic potential survives for shorter duration than S. flexneri 2a. Although some of the physico-chemical parameters had positive relation with duration of survival, the variation of these in natural water samples studied has not caused much variation in the survival in case of S. dysenteriae type 1. In case of S. flexneri 2a, the observed variation in Mg concentration can cause up to 25 days difference in the duration of survival and thus could be a factor determining the endemicity of S. flexneri 2a infection.

Haemolysin production by environmental isolates of Vibrio parahaemolyticus from Andamans.

Sixty marine water samples were collected from various coastal sites around Port Blair at different times during August 1996 to July 1997. The specimens were subjected to standard procedure for isolation and identification of V. parahaemolyticus. Forty four V. parahaemolyticus isolates were detected from these specimens and all showed clear haemolysis on Wagatsuma agar plates. The haemolytic activity was abolished by heating the culture supernatants at 60 degrees C for 10 min and enhanced when plates were kept at 4 degrees C. When isolates were subjected to PCR assay for tdh gene, only one showed the presence of the gene. The results indicate the existence of pathogenic V. parahaemolyticus in the marine environment of these islands.

Existing status of shigellosis in Andaman & Nicobar islands.

A total of 691 children below five years of age, who were suffering from acute diarrhoea, were investigated. Conventional bacterial pathogens were isolated in 133 (19.2%) cases. Shigella sp. was the most common isolate being positive in 72 (10.4%) faecal specimens. No isolation of Shigella sp. was observed in paediatric patients less than 6 months of age while the maximum isolations were observed among 7-12 month old children. All isolates were sensitive to ciprofloxacin, norfloxacin, gentamycin and nalidixic acid and resistant to ampicillin. Multiple drug resistant isolates were observed during the study also. In all, 7 antibiograms were observed.

Colonization ability & intestinal pathology of rabbits orally fed with Vibrio cholerae O139 Bengal.

The colonization ability of a representative epidemic strain of V. cholerae O139 Bengal was studied in the oral rabbit colonization model and the nature of colonization in the ileal and jejunal tissues was examined ultrastructurally. Results of the colonization study and ileal loop assay indicated that the strain proliferates and colonizes the small intestine of the rabbit mucosal surface. Further, the electronmicroscopic study revealed the disruptive effect of the strain on the apical membrane of the epithelial cells. The results of this study suggested that apart from colonization, invasion of the bacteria was important in the pathogenesis of V. cholerae O139 mediated infections.

Etiological agents of diarrhoea.

Two decades of research have established newer pathogens and techniques in establishing several organisms of diarrhoeal diseases as aetiological agents. It is now possible to detect an agent in 80% of the situation of diarrhoea in a standard laboratory. The brief review describes the list of pathogens, their diagnostic techniques with short description on clinical and epidemiological status.

Clinical & bacteriological profiles of shigellosis in Calcutta before & after an epidemic (1984-87).

Patients below 5 yr of age, hospitalised for shigellosis over a period of four years (1984-87), were studied. During the epidemic of bacillary dysentery (1984) isolation of different Shigella spp. as well as Shigella dysenteriae type 1 was high. Decreased isolation of Sh. dysenteriae type 1 and increased isolation of Sh. flexneri was observed during post-epidemic years (1985-87). Isolation of different Shigella spp. was always above 25 per cent from patients with dysentery and greater than 7 per cent from those with watery diarrhoea during the post-epidemic years. Higher incidence of shigellosis was observed amongst older children (greater than 3 yr). Most of the shigellosis patients complained of blood and mucus in stools. Vomiting was common among shigellosis patients presenting with watery diarrhoea whereas fever was commonly seen in patients with both dysentery and watery diarrhoea. Most patients of shigellosis presenting with blood and mucus in stools had no dehydration.