The genetic determinant of the cohemolysin which is responsible for the CAMP phenomenon, a cohemolysis, of Actinobacillus pleuropneumoniae was cloned in Escherichia coli. Total DNA from the A. pleuropneumoniae serotype 1 type strain 4074 was used to construct a gene library in plasmid pUC18 in E. coli JM83. A total of 10,500 clones containing recombinant plasmids have been screened for hemolysis on blood plates. Fifty-five clones which showed a weak hemolytic response after 24 to 48 h of incubation were screened for the CAMP reaction with Staphylococcus aureus. This led to the identification of one clone which showed a positive CAMP reaction. Immunoblot analysis revealed that the recombinant strain expressed a protein with a molecular mass of 27,000 daltons, similar in size to the CAMP protein of the group B streptococci. Rabbit antibodies against the CAMP+ clone neutralized the CAMP reaction mediated by the E. coli strain containing the cloned CAMP gene as well as that of A. pleuropneumoniae. Antibodies raised against the cloned CAMP cohemolysin cross-reacted with Streptococcus agalactiae protein B. We designate the 27,000-dalton molecule CAMP factor protein and name its corresponding gene cfp.

Summary A total of 70 puppies and their dams, distributed in 14 litters, were submitted to weekly fecal examinations for C. difficile during the first 10 weeks after birth. During the study, 94.3% of the puppies and 42.9% of the dams harboured C. difficile at least once in their feces. We calculated that 58% of the puppies carried toxigenic C. difficile at least once during the survey. In the puppies, C. difficile carriage rates ranging from 3.1% to 67.1% were observed at different moments of the observation period. In comparison, C. difficile carriage rate was 1.4% in a control group of healthy dogs more than 3 months old. Discrepancies in the toxigenic phenotype of the C. difficile strains isolated in the same litter showed that the neonate dogs were transiently infected with different strains, and that the dam is often not the source of infection with C. difficile. We could not demonstrate any pathogenicity of C. difficile for neonate dogs.

A sterile plastic tube, a boric acid-glycerol-sodium formate tube and a dip-slide tube were compared for transport of dog urine for bacteriological examination under practice conditions, at ambient temperature.In a first part, 50 dog urine samples were cultured on agar plates and on a dip-slide kit within 2 h after collection and after storage at 20°C in a sterile tube and in a boric acid tube for 24 h and 48 h. Culture of the samples stored in the boric acid tube and culture on the dip-slide yielded results which correlated very well with those of the culture of fresh urine. However, culture of the samples stored in the sterile tube yielded up to 65 % false positive results.In a second part, a comparison was drawn with culture results of 100 dog urine specimens collected by different practitioners and simultaneously mailed to our laboratory in a sterile tube, in a boric acid tube and in a dip-slide kit. Samples sent in the boric acid and in the dip-slide tube showed comparable culture results. Culture of the samples sent in the plastic tube yielded 53 % false positive results in comparison with those of the samples preserved in boric acid.

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