Monocationic surfactant induced ultra structural changes in antibiotic resistant Escherichia coli.

Background & objectives: Cetrimide is a monocationic surfactant, commonly used for disinfection of hospital floors, equipments, for cleansing of burns and wounds, hand wash, etc. We evaluated whether antibiotic resistant (AR) Escherichia coli isolates from hospital settings (nosocomial pathogens) show any evidence of significant reduction in their susceptibility to cetrimide. Also the response of AR E. coli (nosocomial pathogens) to the action of cetrimide was assessed by studying the ultra structural changes induced using transmission electron microscopy (TEM). Methods: A total of 165 clinical samples were screened for isolation of E. coli. Eighty two (49.6%) samples were positive for E. coli. Antibiotic susceptibility testing of E. coli isolates was carried out by Kirby Bauer method to isolate AR E. coli. The randomly selected AR E. coli isolate was treated with different concentrations of cetrimide and minimum inhibitory concentration (MIC) of cetrimide was determined by broth micro dilution method. This same isolate was used for performing time kill assay and TEM study. Results: The test E. coli isolate showed resistance to 12 different antibiotics. The MIC of cetrimide against AR E. coli was 312.5 μg/ml. The ultra cellular structural changes in cetrimide treated AR E. coli revealed vacuole formation, disaxilization of nuclear material, loss of cytoplasmic granularity, bleb formation and cell lysis. Conclusion: Ultra structural changes induced by the action of cetrimide revealed cell damaging changes in the AR E. coli to be dose and time dependent. The results showed that antibiotic resistance does not alter any change in susceptibility of E. coli to cetrimide, which was found to be still an effective disinfectant against a nosocomial pathogen E. coli.

Single dose therapy of ascariasis--a randomized comparison of mebendazole and pyrantel.

A multicentre, randomized trial was carried out to compare the efficacy of two single-dose treatments for ascariasis: mebendazole 200 mg, and pyrantel 10 mg/kg. Each centre enrolled 200 patients with a suspected diagnosis of ascariasis, 100 for each treatment, and the treatments were randomized for each centre. To confirm the diagnosis, stools were examined for eggs of Ascaris lumbricoides by Kato's thick smear method. Efficacy was evaluated by stool examination repeated three weeks after treatment by a "blind" technician using two methods, viz. Kato's thick smear method and the zinc sulfate flotation method. Cure was defined as absence of ascaris eggs in the stools by both methods. Of the 600 enrolled patients, 32 were excluded from analysis as their initial stool examination was negative, and 568 completed the trial: 284 on each treatment. The cure rate was 80 per cent in the mebendazole group and 90 per cent in the pyrantel group (P less than 0.01). Thus pyrantel was found to be significantly more efficacious than mebendazole for single-dose treatment of ascariasis.