Seventeen strains of Yersinia enterocolitica biotype 4 serotype 03 were isolated from 63 apparently healthy puppies. Of these strains, 76.4% showed both multiple resistance to antimicrobial agents and lack of sorbose fermentation.

Of 2,500 fecal samples collected from children with diarrhea in the province of Siena, 35 (1.4%) were found to be positive for Yersinia enterocolitica. Of the isolates, 94.2% belonged to biotype 4, serotype 0:3; 2.8% belonged to biotype 2, serotype 0:9; and 2.8% belonged to biotype 1, serotype 0:6. The in vitro pathogenicity tests showed that all but two isolates were calcium dependent and autoagglutinable and that all but one were also invasive in HEp-2 cell culture. As regards plasmid content, 32 of 33 biotype 4, serotype 0:3 strains harbored a plasmid of 48 megadaltons and 1 strain also harbored a small plasmid of 2 megadaltons. The biotype 2, serotype 0:9 strain harbored a plasmid of 42 megadaltons; one of the two strains lacking plasmids belonged to biotype 1, serotype 0:6, and the other belonged to biotype 4, serotype 0:3. Pyrazinamidase activity was positive only for the biotype 1, serotype 0:6 strain. Esculin was hydrolyzed only by the biotype 1, serotype 0:6 strain.

Thirteen strains of Yersinia spp. were isolated at the Rome zoo and at Castelporziano, a game preserve near Rome. The strains were tested for calcium dependency, autoagglutination, heat-stable toxin production, 50% minimum lethal dose in mice (LD50), pyrazinamidase activity and content of plasmids by electrophoresis in agarose gel. The former three tests were negative for all strains, the LD5 was always 1 x 10' CFU/ml and pyrazinamidase activity was positive for all strains. Electrophoresis revealed the presence of two plasmids of 27 and 66 megadaltons (MDa) in the two strains of Y. enterocolitica of serotype 027 isolated from animals in the zoo. The two strains of the same species and serotype, isolated from wild animals harboured a 42-MDa plasmid. A small plasmid of 2 MDa was found in two strains of Y. enterocolitica of serotype 07,8 from two subsequent samples of a zoo animal.

Legionella pneumophila serogroup 1 was isolated from post mortem specimens from 13 out of 58 patients with pneumonia diagnosed at autopsy. The results of a study undertaken in the hospital environment showed that the water plumbing system was colonized with L. pneumophila serogroup 1 which could also be isolated from respiratory devices filled with tap water. Control measures instituted are described.

Plasmid analysis and restriction-endonuclease digestion were used to study 54 clinical and environmental Legionella strains. Plasmids with approximate molecular masses of 40, 50, 70, and 90 megadaltons (Mdal) have been isolated from L. pneumophila serogroup 1 strains. One L. jordanis strain contained two plasmids of 25 and 70 Mdal. Restriction analysis of clinical and related hospital-environmental isolates resulted in identical patterns. Geographic diversity is shown for strains of different origin.