Actinomycetes associated with abscess formation in a goat, a llama and two alpacas

Abstract

The genera Actinomyces and Schaalia, both members of the bacterial order Actinomycetales, include relevant infectious agents that cause abscesses in small ruminants and New World camelids. Due to the high diversity of the Actinomycetales, detection of undescribed members of this order is to be expected. Novel actinomycetes species were cultivated from a goat, a llama and two alpacas suffering from abscesses with suspected caseous lymphadenitis (CLA). Analyses carried out on these isolates using MALDI-TOF MS and 16S rRNA gene sequencing revealed actinomycetes, presumably belonging to the bacterial genera Actinomyces and Schaalia. The data suggest that the caprine isolate is a undescribed Actinomyces species, while the isolates originating from a llama and two alpacas show a close relationship to each other within a unique Schaalia cluster, suggesting a host-adapted novel Schaalia species. Both methods proved equally suitable for reliable identification of known and of undescribed Actinomyces and Schaalia species. This study contributes to extending our knowledge about novel species belonging to the bacterial family of Actinomycetaceae (actinomycetes) associated with abscesses in goats and New World camelids. Precise identification of actinomycetes at species level is of high relevance in veterinary practice with regard to differentiation from caseous lymphadenitis and assessment of treatment success.

Keywords

• small ruminant
• New World camelids
• pseudotuberculosis
• Actinomyces
• Actinomycetes
• Actinomycetaceae
• Schaalia