Antibiotic resistance among indicator bacteria isolated from healthy pigs in New Zealand.

AIM: To determine the resistance to antibiotics among the indictor bacteria, Escherichia coli and Enterococcus spp, isolated from the faeces of healthy pigs on three conventional pig farms and one organic farm in the North Island of New Zealand. METHODS: Faecal samples, collected at intervals between March and October 2001, were plated onto MacConkey agar and Slanetz-Bartley agar and examined after 1-3 days incubation for colonies resembling E. coli and Enterococcus spp, respectively. Typical colonies were subcultured for further identification and storage. The isolates were tested for antibiotic resistance, using disc diffusion, to ampicillin, gentamicin, streptomycin, and tetracycline. Escherichia coli isolates were also tested for resistance to ciprofloxacin, cotrimoxazole and neomycin. Enterococcus spp isolates were also tested for resistance to vancomycin, erythromycin and virginiamycin. RESULTS: A total of 296 E. coli and 273 Enterococcus spp isolates were obtained from the three conventional farms, and 79 E. coli and 80 Enterococcus spp isolates were obtained from the organic farm. All the E. coli isolates from both the conventional and organic pig farms were susceptible to ciprofloxacin, and all the Enterococcus spp isolates were susceptible to ampicillin, gentamicin and vancomycin. Isolates of E. coli from conventional pig farms were resistant to gentamicin (0.7%), neomycin (0.7%), ampicillin (2.7%), cotrimoxazole (11%), streptomycin (25%) and tetracycline (60%). Enterococcus spp isolates from the same farms were resistant to erythromycin (68%), tetracycline (66%), streptomycin (54%) and virginiamycin (49%). By contrast, for the organic pig farm

Controlled production of cirrhosis in the rat liver.

In the present study we propose a standardization of the method for the induction of fibrosis of the liver in rats by weekly administration of CCl4 by the intragastric route. The present method is a variation of that described by Proctor and Chatamra. The initial CCl4 dose is 0.04 ml (X dose) but the subsequent doses are calibrated using a 5% variation in animal weight as a reference point. For a weight gain of 5% or more, the successive doses are progressively increased by 50 to 150% (1.5X, 2X, 2.5X). When there is no variation in weight or loss in less than 5%, the previous dose is maintained. For a weight loss of more than 5%, the CCl4 dose is decreased by 50%. Consistent fibrosis if obtained as early as during the 8th week. Collagen content increases progressively from the 8th to the 12th week, reaching on average a level eight-fold higher than that observed in the control.