Campylobacter taeniopygiae sp. nov., Campylobacter aviculae sp. nov., and Campylobacter estrildidarum sp. nov., Novel Species Isolated from Laboratory-Maintained Zebra Finches

Zebra finches (Taeniopygia guttata) are laboratory animal species commonly used for modeling neurobiology and learning. Historically, using bacterial culture, biochemical analysis, and 16S ribosomal RNA gene sequencing, bacterial isolates from feces of finches housed at Massachusetts Institute of Technology had been presumptively diagnosed as Campylobacter jejuni, which is commonly isolated from both domestic and wild birds. Although the zebra finches were not clinically affected, C. jejuni is a known zoonotic pathogen that causes gastroenteritis in humans worldwide. Human transmission is predominantly foodborne and associated with the consumption of contaminated poultry; however, humans can also become infected from contact with C. jejuni-infected reservoir hosts. Because C. jejuni-infected finches pose a risk to research personnel, a study was undertaken to investigate the prevalence and taxonomic identification of Campylobacter spp. present in the finch colony. Campylobacter spp. were isolated from a total of 26 finch fecal samples collected in 2003, 2010, and 2017. 16S ribosomal RNA sequencing of all isolates determined that they shared 99% identity with either C. jejuni or Campylobacter lari. Sixteen of the isolates were subjected to further biochemical characterization and atpA and rpoB gene sequence analysis. Based on these analyses, three clusters of Campylobacter species were identified. The draft whole-genome sequences were determined for one representative isolate from each cluster. A pan-genomic phylogenetic tree, average nucleotide identity, digital DNA-DNA hybridization, and orthologous gene analyses indicated that each isolate was its own novel species, distinct from C. jejuni and other avian Campylobacter species. We have named these novel species Campylobacter taeniopygiae, Campylobacter aviculae, and Campylobacter estrildidarum, and in each novel species, we identified virulence genes suggesting their pathogenic and zoonotic potential.