ABSTRACT
Aerococcus is a genus of aerobic gram-positive cocci that resemble enterococci but do not form chains. They are frequently isolated as airborne saprophytes in hospitals and as a pathogen of lobsters, cause greening in blood agar, and grow in the presence of 40% bile. In humans, they are found in endocarditis and in urinary tract infections and also some other health-related problems such as spondylodiscitis, lymphadenitis, and so forth.1-3
The genus Aerococcus was initially described by Williams.4 Aerococcus viridans has been isolated from a broad range of habitats such as air, vegetation, dust, soil, and meat-curing brines, and has also been associated, although rarely, with human infections. Despite its presence in such diverse sources, the taxonomic kinship of strains has been consistently demonstrated.5 Later on, Aerococcus urinae was proposed as a new species based on analysis of 16S rRNA sequences.6 A. urinae was isolated from urine of elderly persons suffering from urinary tract infections and from blood of patients with endocarditis and urosepticemia. Aerococcus spp. is a rarely reported pathogen, possibly due to difŠculties in the identi-Šcation of the organism. A. urinae is a gram-positive coccus that grows in pairs and clusters, produces alpha-hemolysis on blood agar, and is negative for catalase and pyrrolidonyl aminopeptidase. A. viridans organisms are gram-positive cocci with a strong tendency to form tetrads. A. urinae and A. viridans slightly differ in their reactions in the LAP and pyronylaminopeptidase (PYR) disk tests. A. urinae has the characteristics of being LAP-positive and PYR-negative,
whereas A. viridans is LAP-negative and PYR-positive.7,8 More recently, three additional species of Aerococcus have been described, based on 16S rRNA sequences and polyphasic taxonomy.9 Aerococcus urinaehominis has been recovered from a urine culture,5 Aerococcus sanguicola has been isolated from urine and blood,10 and A. christensenii has been recovered from a vaginal specimen.11
