Carbapenems

    • Imipenem, meropenem, ertapenem, doripenem: GNB, anaerobes, strep. staph, neutropenic fever.

    • Imipenem 500 mg - 1 g IV/IM q6-8h, meropenem 1-2 g IV q8h or 500 mg IV q6h, doripenem 500 mg IV q8h, and ertapenem 1 g IV q24h are the currently available carbapenems.

    • Bactericidal by interfering with cell wall synthesis, similar to PCNs and cephalosporins and are active against most gram-positive and gram-negative bacteria, including anerobes. ABx of choice for infections caused by organsims producing AmpC or extended-spectrum beta-lactamases (ESBLs). Not effective against Burkholderia cepacia, Stenotrophomonas maltophilia, MRSA, E. faecium, and many coagulase-negative staphylococci.

Tx:

    • For many ABx resistant bacterial infections at most body sites.

    • Used for severe polymicrobial infections, including Fournier's gangrene, intra-abdominal catastrophes, and sepsis in immunocompromised hosts.

    • Notable bacteria that are resistant to carbapenems include ampicillin-resistant enterococci, MRSA, Stenotrophomonas, Burkholderia, and Klebsiella pneumoniae carbapenemase (KPC) producing gram-negative organisms. In addition, ertapenem does not provide reliable coverage against P. aeruginosa, Acinetobacter, or enterococci; therefore, imipenem, doripenem, or meropenem would be preferred for empiric treatment of nosocomial infections when these pathogens are suspected. Meropenem is the preferred carbapenem for treatment of CNS infections.

Special Considerations:

    • Carbapenems can precipitate seizure activity, especially in older patients, individual with renal insufficiency, and patients with preexisting seizure d/o or CNS pathology. Carbapenems should be avoided in these patients unless no reasonable alternative therapy is available. Seizures are less common with meropenem and it is therefore indicated in meningitis. Like cephalosporins, carbapenems have been rarely associated with anaphylaxis, interstitial nephritis, anemia, and leukopenia.

    • Patients who are allergic to PCNs/Cephalosporins may have a cross-hypersensitivity reaction to carbapenems, and these agents should not be used in a patient with a reported severe PCN allergy without prior skin testing, desensitization, or both. Prolonged therapy (> 2 weeks) is typically monitored with a weekly serum creatinine, LFTs, and CBC.