In the setting of increasing macrolide use, pneumococcal resistance has become common. Most resistant strains have MICs in the range in which treatment failures have been reported. Further study and surveillance are critical to understanding the clinical implications of our findings.

A Staphylococcus aureus isolate with reduced susceptibility to vancomycin was obtained from a dialysis patient with a fatal case of bacteremia. Comparison of the isolate with two methicillin-resistant S. aureus (MRSA) isolates obtained from the same patient 4 months earlier suggests that the S. aureus with reduced susceptibility to vancomycin emerged from the MRSA strain with which the patient was infected. Atypical phenotypic characteristics, including weak or negative latex-agglutination test results, weak or negative-slide coagulase test results, heterogeneous morphologic features, slow rate of growth, and vancomycin susceptibility (by disk diffusion test) were observed.

Gastrointestinal disorders of varying severity were observed in 239 (53%) of 455 campers and staff members at a coed summer camp in Sullivan County, New York, during July 1981. Five of seven hospitalized patients had appendectomies before the disease was recognized as yersiniosis. Yersinia enterocolitica serogroup O:8 (American strain) was isolated from 37 (54%) of 69 persons examined, including the head cook and 3 others of the 11-person kitchen staff. Of 48 food, water, and environmental samples collected from the camp area, Y. enterocolitica isolates belonging to the same serogroup and biogroup as the human isolates were recovered from dissolved powdered milk, a milk dispenser, and turkey chow mein. This laboratory finding supported the epidemiological data indicating a correlation between consumption of these foods and illness. Y. enterocolitica isolates of the same biogroup as the O:8 isolates but belonging to serogroup O:34 were also isolated from six campers and two samples of dissolved powdered milk. Pathogenicity studies on the Yersinia isolates were performed with three in vitro tests (calcium dependency, autoagglutination, and HeLa cell infection) and one in vivo test (intraperitoneal challenge of mice). Most of the serogroup O:8 human isolates and the chow mein isolate were positive in all four tests. Milk isolates of serogroup O:8 were positive in the in vitro tests but were relatively avirulent in mice, whereas serogroup O:34 isolates, regardless of source, were negative in all four tests.

Fecal specimens for Yersinia screening were obtained from a variety of wild mammals, birds, reptiles, fish, and invertebrates throughout New York state. One specimen from each of 1,426 animals was examined. A total of 148 isolates of Yersinia enterocolitica and related species were obtained from 133 (9.3%) of the animals. Y. enterocolitica was isolated from 100 (7%) of the animals tested, including 81 (10%) of 812 mammals and 19 (3.3%) of 573 birds. Y. intermedia, Y.frederiksenii, and Y. kristensenii were isolated from 39 (2.7%), 5 (0.35%), and 4 (0.28%) animals, respectively. The 81 Y. enterocolitica isolates from mammals belonged to 15 serogroups and included three pathogens: two isolates of typical serogroup 0:8, the "American strain," one from a gray fox (Urocyon cinereoargenteus) and one from a porcupine (Erethizon dorsatum); and one isolate of serogroup 0:3, bacteriophage type IXb, the "Canadian strain," from a gray fox. The most prevalent serogroups recovered from mammals were 0:6,31 (16 isolates) and 0:5,27 (6 isolates). The 19 isolates of Y. enterocolitica from birds belonged to nine serogroups and included one serogroup 0:6,31 isolate from a common grackle (Quiscalus quiscula) and two serogroup 0:5,27 isolates from great horned owls (Bubo virginianus).

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