Antibiotic resistant Escherichia coli on a commercially prepared chicken carcass colonized the gut of a human volunteer handling the raw meat. Strains from both sources, identified on the basis of serotype and characterization of plasmids carried, were found to be identical.
The distribution of O-antigen types of Escherichia coli in calves over a ten-month period has been determined. A total of 400 calves from separate farms located over a wide area of England and Wales have been surveyed. Of the 148 0-types recognized, 93 were found in calves, compared with 107 in a previous survey in man; 42 of these were common to both hosts. In calves 60% of isolates were resistant to at least one antibiotic. Of these, 71 belonged to ten O-types, 9 of which were found in man. It is concluded that calves form a potential reservoir of R plasmid carrying E. coli.
The 0-antigen types of 600 independently isolated Escherichia coli strains from human feces have been determined, and the types have been related to the antibiotic resistance pattems of the strains. The relative abundance of each 0-antigen type differed in the susceptible and resistant series of strains. The majority (86%) of the resistant strains carried R plasmids. Resistant E. coli (20.3%) were found associated with 0-antigen types 8, 9 and 101, whereas the susceptible strains covered a wide range of 0-antigen types. Examination of 174 resistant strains isolated from calf feces also showed a prevalence of 0-antigen types 8, 9, 101 (24.1%), and it seems probable that strains expressing these three 0-antigen types commonly carry R plasmids in the alimentary tracts of man and calves. The number of strains not typeable with the 0 sera available were similar in the human (12.5%) and the calf (11.5%) series. There are no grounds for distinguishing "human" from "calf' E. coli on the basis of their 0-antigen reactions.
A study of calves and pigs was made to compare the effects on intestinal coli-aerogenes bacteria of feeding diets medicated with tetracycline, nitrovin or quindoxin. Results showed that even before the introduction of medicated diets, drug-resistant coli-aerogenes bacteria were present in surprisingly high numbers. However, it was clear with both animal species that only tetracycline had a selective effect. With calves a resistance to furazolidone was frequently present in tetracycline-resistant organisms. Analysis of the resistance patterns supported the contention that the dominant coli-aerogenes bacteria in the gut flora following use of certain growth-promoters, resulted from suppression of fully sensitive organisms: the distribution of the various resistance patterns was independent of the agent used and whether or not the diet was medicated. There was no significant difference in the transmissibility of resistance genes between calves and pigs receiving either tetracycline or quindoxin or neither treatment. Results obtained with nitrovin were thought to be similar but, inexplicably, the control animals all gave low values.
A theoretical study of the expected distribution of Escherichia coli serotypes among samples randomly drawn from populations containing different numbers, ranging from 2 to 40, was compared with experimental data based on the examination of 10 and 100 coiony samples from the same specimens. From these studies it was possible to lay down guide lines for the planning of efficient sampling programmes for determining most or all serotypes present in various animal species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.