Genotypic and phenotypic determination of five virulence markers in clinical isolates of Escherichia coli.

The presence of the virulence markers K1 capsule, serum resistance, aerobactin, S and P/PR fimbriae were examined in a total of 395 E. coli strains from different extraintestinal infections and in 81 faecal isolates of healthy volunteers using specific DNA probes and classical phenotypic methods. All markers were more frequently detected when genotypic assays were applied. The simultaneous occurrence of 3-4 virulence determinants was typical for isolates derived from patients with septicaemia or meningitis. Isolates from blood cultures and cerebrospinal fluid were expressing the virulence phenotypes to a greater extent than isolates from urine or faeces. The use of colony hybridization with specific oligonucleotide and polynucleotide probes for the detection of virulence determinants has been proven to be more specific and reliable than phenotypic approaches.

Hereditary compulsive self-mutillating behaviour in laboratory rabbits.

During the last few years an increasing number of cases of extensive automutilation has been observed in a rabbit breeding colony of Checkered crosses. Digits and pads of the front feet were traumatized. No other behavioural abnormalities or signs of disease were evident. Self-mutillation was seen both in stock, breeding and experimental animals, in rabbits kept singly in cages and in those housed in groups on the ground, in rabbits kept in different buildings and under the care of different staff members. This behavioural abnormality of Checkered crosses has also been observed in animals after being placed into other institutions or private homes. No evidence of an agent responsible for the occurrence of self-injury could be found with parasitological, mycological, histological, clinical or haematological examination. Twelve to 16 animals are affected yearly in a colony varying in size between 130 and 230 rabbits. Following complete healing, relapses occurred up to 3 times per year, on either the same or the opposite front foot. In the last 21 cases episodes of automutillation could be regularly interrupted with the dopamine antagonist, haloperidol. Similar signs of auto-mutillation were never seen in animals of another breeding line kept in the same building and under the same conditions nor in animals brought in from other breeding colonies. A relatively high coefficient of inbreeding can be presupposed in this 15-year-old breeding colony of Checkered crosses. A genetic predisposition for the behavioural anomaly described appears very likely.