Aerobic bacterial flora of the vagina and prepuce of California sea lions (Zalophus californianus) and investigation of associations with urogenital carcinoma

To investigate the association between genital bacterial infection and urogenital carcinoma in California sea lions (Zalophus californianus), vaginal and preputial swabs for bacterial isolation were taken from 148 free-ranging and 51 stranded California sea lions including 16 animals with urogenital carcinoma. Cytological examination of vaginal or preputial smears showed a majority (65.5%, 57/87) of animals examined had mild or no inflammation. Aerobic bacteria were isolated from 116 (78.4%) wild sea lions and 100% of stranded animals. A total of 403 isolates were identified representing 51 unique bacterial species. The median number of isolates per animal increased with age in the wild group, but there was no difference in the number of isolates per animal between wild and stranded adults. The most common bacteria isolated from the wild sea lions were Psychrobacter phenylpyruvicus (39 isolates), non-hemolytic Streptococcus (35 isolates), Corynebacterium spp. (30 isolates), and Escherichia coli (20 isolates). More bacterial species were isolated from stranded animals than wild animals (33 versus 26) and there was significantly less growth of P. phenylpyruvicus, Corynebacterium spp., and Moraxella-like spp. in the stranded animals. Beta-hemolytic Streptococcus was the only bacterium significantly associated with urogenital carcinomas in California sea lions, but only in females.