Pocket Oncology (Pocket Notebook Series), 1st Ed.

ANTIMICROBIAL THERAPY

Cesar J. Figueroa and Monika K. Shah

Overview

Understanding the complexity of infectious complications faced by oncologic pts & the changes in patterns of drug resistance is necessary to provide adequate anti-infective support.

Some Clinically Relevant Bacteria

Gram negatives: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus spp, Serratia marcescens, Acinetobacter baumannii, Enterobacter cloacae, Citrobacter spp, Providencia spp, Legionella pneumophilia, & non-pneumophila spp.

Gram positives: MSSA, MRSA, Coagulase-negative Staphylococcus, Enterococcus faecalis/faecium, Streptococcus pneumoniae, Streptococcus viridans group, Group A & B Streptococcus, Listeria monocytogenes.

Anaerobes: Fusobacterium spp, Bacteroides spp, Clostridium spp, Lactobacillus.

Selected Clinical Syndromes and Antimicrobials of Choice

Agents with Anaerobic Coverage

MNZ, Clindamycin, Beta-lactam/Beta-lactamase inhibitor, Carbapenems

Monitoring of Selected Antibacterials

• Vancomycin: Trough serum conc. most accurate & practical for monitoring efficacy → obtain before 4th dose (steady-state): Recommended in pts w/renal fxn changes or those needing prolonged Tx courses (Am J Health Syst Pharm2009;66:82)

• Most antibacterials: Need dose-adjustment based on GFR, few exceptions need dose-adjustment for liver dysfunction (ie, Cftx, tigecycline)

• All Beta-lactams: Ability to induce seizures at ↑ conc.; neurotoxicity reported w/use of carbapenems → risk w/Imipenem ↓ w/careful attention to dosage (Antimicrob Agents Chemother 2011;55:4943)

• AG & Polymyxin have the greatest potential for renal tox & should be used & monitored carefully in pts w/pre-existent renal disease.

Some Clinically Relevant Fungi

Yeast: Candida → albicans & non-albicans (ie, glabrata, krusei, parapsilosis, tropicalis, dubliniensis, guillermondii); Cryptococcus, Trichosporon.

Mold: Aspergillus → fumigatus (most common), flavus, terreus, niger; Mucormycosis agents → Mucor, Rhizopus, Cunninghamella, Rhizomucor, etc.; Fusarium; & Dematiaceous molds.

Dimorphic: Histoplasma, Coccidioides, Blastomyces, Paracoccidioides.

Commonly Used Antifungals

• Candidemia: IV central-catheter removal & ophthalmologic exam are recommended in all cases of Candidemia.

• In non-neutropenic pts → use Fluconazole or an Echinocandin

• If mod to severely ill OR neutropenic → echinocandins are preferred. Voriconazole is an adequate alternative if mold coverage is desired (Clin Infect Dis 2009;48:503)

• Aspergillosis: Voriconazole preferred, alternative: Liposomal Ampho B, dosing schemes vary, though use at higher doses (ie, 10 mg/kg/d vs. 3 mg/kg/d), a/w higher tox but no additional clinical benefit (AMBILOAD Clin Infect Dis 2007;44:1289)

Selected Antivirals and Therapeutic Uses