Aerococcus spp.
Aerococcus urinae, Aerococcus viridans, Aerococcus sanguinicola
The bacteria
Aerococcus genus, a firmicute, was first identified in 1953 [Williams, 1953]. Multiple species have been identified since then; not all of them are human pathogens.
Laboratory identification
Aerococcus is a gram-positive coccus in clusters (like Staphylococcus), alpha-hemolytic on blood agar and catalase-negative (like Streptococcus).
Identification can be made using automated systems API, 16S rDNA sequence analysis or MALDI ToF. Automated systems may not have all the species in the database.
Differentiating Aerococcus from other similar organisms:
Differentiating between Aerococcus sp.
Clinical presentation
A urinae is known to cause
UTI in elderly (median age 75 y; F>M) people with comorbidities (Diabetes Mellitus, malignancy, prostatitis, indwelling catheter etc)
bacteraemia (mostly as a complication of UTI),
endocarditis (a complication of bacteraemia – 1/3rd of bacteraemia cases; poor prognosis)
and rarely other infection (see chart above).
The prevalence of these bacteria in the urine is 0.3-4%.
A urinae is often seen in mixed-blood culture with – St aureus, E coli, Actinobaculum schaalii.