Coryneform bacteria associated with canine otitis externa.

Aalbæk B1, Bemis DA, Schjærff M, Kania SA, Frank LA, Guardabassi L.

Abstract

This study aims to investigate the occurrence of coryneform bacteria in canine otitis externa. A combined case series and case-control study was carried out to improve the current knowledge on frequency and clinical significance of coryneform bacteria in samples from canine otitis externa. A total of 16 cases of otitis externa with involvement of coryneform bacteria were recorded at two referral veterinary hospitals in Denmark and the US, respectively. Coryneform bacteria were identified by partial 16S rRNA gene sequencing. Corynebacterium auriscanis was the most common coryneform species (10 cases). Small colony variants of this species were also observed. Other coryneform isolates were identified as Corynebacterium amycolatum (3 cases), Corynebacterium freneyi (2 cases) and an Arcanobacterium-like species (1 case). The coryneform bacteria were in all cases isolated together with other bacteria, mainly Staphylococcus pseudintermedius alone (n=5) or in combination with Malassezia pachydermatis (n=5). Some coryneform isolates displayed resistance to fusidic acid or enrofloxacin, two antimicrobial agents commonly used for the treatment of otitis externa in dogs. The frequency of isolation of coryneform bacteria was 16% among 55 cases of canine otitis externa examined at the Danish hospital during 2007. In contrast, detectable levels of coryneform bacteria were not demonstrated in samples from the acustic meatus of 35 dogs with apparently healthy ears, attending the hospital during the same year. On basis of the current knowledge, these coryneform bacteria should be regarded as potential secondary pathogens able to proliferate in the environment of an inflamed ear canal.

Regards

http://www.ncbi.nlm.nih.gov/pubmed/20434850

Thank you doctor, but is there other studies on the improvement of clinical symptoms after antibiotic therapy in dogs ? what about humans ? Should we consider these coryneform ?

The most common bacteria isolated from the middle ear in acute otitis media (AOM) are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. Corynebacteria also have been isolated, but are likely secondary infections of which the relative pathogenicity of these species are not yet known. See attached link for more information.

http://www.sciencedirect.com/science/article/pii/S2090074014000218

They are rarely pathogenic in immune compromised patients.