2025 – PAGE 138 – CARDIOLOGY

ACUTE BACTERIAL ENDOCARDITIS

Patients with acute bacterial endocarditis present acutely toxic with high fever and possibly a septic picture. The most common etiology is STAPH AUREUS.

SUBACUTE BACTERIAL ENDOCARDITIS

Patients with subacute bacterial endocarditis present with vague symptoms lasting for weeks, rather than acutely toxic. The most common organism is STREP VIRIDANS. Aortic valves are especially vulnerable.

MNEMONIC: “VERDE sounds like VIRIDANS and means GREEN in Spanish. Imagine VERDE DECAY in teeth (a common hideout for viridans) entering the blood stream during flossing and settling on heart valves.”

DIAGNOSING ENDOCARDITIS

Negative blood cultures make diagnosing a bacterial endocarditis extremely unlikely. Even if a vegetation is seen on echocardiogram, the likelihood of a bacterial endocarditis in the presence of negative blood cultures is very low.

TREATMENT OF ENDOCARDITIS

The treatment of endocarditis VARIES based on the type of valve affected (native vs. prosthetic).

NATIVE VALVE ENDOCARDITIS

• MNEMONIC: NATIVE = “NATIVITY” or natural, like a BABY. If you don’t have evidence of a Staphylococcal infection, treat native valve endocarditis the same way you would empirically treat a septic BABY: with Ampicillin and Gentamicin.
• PENICILLIN-SENSITIVE STREP: You may use a single antibiotic agent (Penicillin, Ampicillin, Ceftriaxone, or Cefazolin for 4 weeks). You may also use Ampicillin + Gentamicin for 2 weeks. Again, a single agent is fine if you have sensitivities. Strep viridans is still highly susceptible to PCN.
  • NOTE: If a patient is allergic to PCN, you may use Vancomycin (although it is not as effective as the beta lactams against Strep).
• PCN-INSENSITIVE STREP SPECIES (likely Enterococcus): Ampicillin + Gentamicin
  • PEARL: Although Enterococcus is no longer susceptible to PCN, Ampicillin and Amoxicillin do still work.
• STAPH AUREUS (non-MRSA): Any anti-Staph drug is fine (Cefazolin, Oxacillin, Nafcillin or Vancomycin)
• METHICILLIN RESISTANT STAPH AUREUS (MRSA): Vancomycin + Gentamicin ± Rifampin