Aerococcal infection at three US Tertiary Care Hospitals

The aim of the present study was to determine clinical features of Aerococcus infections and the significance of the Aerococcus species isolated from any clinical samples.

Electronic records of all cultures yielding Aerococcus species from 2002 to 2012 were obtained from three tertiary care hospitals. We performed an in-depth review of medical records.

Aerococcus was isolated from ≥ 1 site in 93 patients. Blood cultures were positive in 64 patients; 15 with definite bacteremia, including 3 with endocarditis, 7 with urinary tract infections, 13 with probable bacteremia, and 36 in which Aerococcus was judged to be a possible contaminant. Of 19 urine isolates, 10 were from patients with symptomatic urinary tract infections and 7 were from patients with asymptomatic bacteriuria; in 2 cases, urine isolates were regarded as possible contaminants. Most patients with urinary isolates had underlying urological abnormalities. Other sources for Aerococcus included synovial fluid, bile, bone, intraabdominal abscess, and ovarian abscess. All of the isolates tested with ampicillin, cefazolin, clindamycin, and vancomycin were susceptible. A total of two patients with definite Aerococcus infection died, but all of the others responded to antibiotic therapy.

Aerococcus often is considered a contaminant; however, in our case series, 35% of cases in which Aerococcus was isolated from any site indicated a definite infection. In patients with positive blood cultures for Aerococcus, at least 23% were associated with infection. Appropriate attention needs to be directed to Aerococcus when it is isolated from a normally sterile site.