Treatment of Aerococcus sanguinicola Infections
Penicillin or ampicillin should be the first-line treatment for Aerococcus sanguinicola infections, with consideration of adding an aminoglycoside for severe invasive infections such as infective endocarditis. 1, 2
Antimicrobial Susceptibility Profile
All reported A. sanguinicola isolates demonstrate consistent susceptibility to penicillin, ampicillin, cefuroxime, vancomycin, erythromycin, and rifampicin. 1
Low MIC values are consistently documented for penicillin, cefotaxime, and vancomycin across multiple case series. 3
Ceftriaxone, penicillin G, and vancomycin show reliable activity against both A. sanguinicola and the related species A. urinae. 4
Treatment Recommendations by Clinical Presentation
Uncomplicated Urinary Tract Infections
For simple UTI with A. sanguinicola, penicillin or ampicillin is the preferred agent based on consistent susceptibility patterns. 1, 2
Avoid empiric use of trimethoprim-sulfamethoxazole or fluoroquinolones, as their efficacy against aerococci remains uncertain. 2
Ceftriaxone represents a reasonable alternative for patients unable to tolerate penicillins. 4
Bacteremia and Severe Sepsis
Initiate intravenous penicillin G or ampicillin immediately for A. sanguinicola bacteremia, particularly in elderly men with urinary tract abnormalities. 3
For patients meeting criteria for severe sepsis (which occurs in the majority of bacteremia cases), use high-dose intravenous beta-lactam therapy. 3
Vancomycin serves as an appropriate alternative for patients with documented penicillin allergy. 1, 3
Infective Endocarditis
For A. sanguinicola endocarditis, combine penicillin with an aminoglycoside (gentamicin) to enhance bactericidal activity. 2
This combination therapy mirrors the approach used for viridans group streptococcal endocarditis, given the similar susceptibility patterns. 5, 2
Urgent cardiology and cardiac surgery consultation is mandatory, as A. sanguinicola can cause rapid valve destruction and death before surgical intervention. 6
Treatment duration should extend for 4-6 weeks for native valve endocarditis, following standard endocarditis treatment principles. 5
Critical Clinical Context
High-Risk Patient Population
A. sanguinicola predominantly affects elderly males (median age 70-82 years) with underlying urinary tract pathology including indwelling catheters, urinary retention, or structural abnormalities. 1, 3
Patients with neurological disorders (dementia, cerebral degeneration, myelomeningocele) represent a particularly vulnerable population. 1, 3
Source Control Considerations
Identify and address the primary infection source, most commonly the urinary tract (present in approximately 50% of cases) or gallbladder. 1
Remove indwelling urinary catheters when feasible, as they serve as a nidus for persistent infection. 3
Evaluate for underlying urological abnormalities requiring surgical correction to prevent recurrence. 2
Important Pitfalls to Avoid
Do not dismiss A. sanguinicola as a contaminant—it is a true pathogen capable of causing severe invasive disease including fatal endocarditis. 6, 2
Aerococci are frequently misidentified as streptococci or staphylococci on Gram stain, leading to inappropriate empiric therapy; MALDI-TOF mass spectrometry provides accurate identification. 2
The prognosis of bacteremia without endocarditis is generally favorable, but untreated infections can progress to urosepsis and death. 4, 2
Long-term prognosis often reflects the underlying frailty and comorbidities of affected patients rather than treatment failure. 1
Monitoring and Follow-up
Obtain repeat blood cultures 48-72 hours after initiating therapy to document clearance of bacteremia. 3
For endocarditis cases, perform serial echocardiography to assess valve function and detect complications such as abscess formation or progressive valve destruction. 6
Monitor renal function closely in elderly patients receiving aminoglycoside therapy, adjusting doses based on creatinine clearance. 5