Avoiding serious interactions with long-term antibiotics for bone or joint infections
Quinolones are used for staph and diabetic foot infections. Watch for mental status changes, especially in the elderly or those with poor renal....
More ORAL antibiotics will be used for bone or joint infections. IV antibiotics for 6 weeks or longer used to be standard. But switching to orals after just 1 to 2 weeks is usually as effective, more convenient, and less costly. Help patients avoid serious interactions and toxicities with these long-term antibiotics. Explain that missed doses can lead to treatment failure, complications, and switching back to IV therapy.
- Quinolones are used for staph and diabetic foot infections. Watch for mental status changes, especially in the elderly or those with poor renal function. Make sure dosing is appropriate. Advise diabetes patients to monitor glucose. Quinolones can cause hypo- or hyperglycemia AND recommend adjusting diabetes medications if needed. Tell patients to report tendon pain or swelling, it's more common with the higher doses used for bone and joint infections.
- Trimethoprim/sulfamethoxazole (TMP/SMX) is used for staph, including MRSA. But interactions with warfarin can lead to a 3-fold bump in INR.
- If warfarin and TMP/SMX must be used together, recommend monitoring INR at least weekly until stable and expect to have to reduce the warfarin dose by 25% to 50% to reduce bleeding risk.
- Rifampin is sometimes added to improve staph coverage. It's a potent CYP450 enzyme INDUCER and can significantly reduce levels of many drugs, including warfarin. If warfarin must be used, recommend checking INR at least weekly until stable, and expect the dose to be increased up to 5-fold. When rifampin is stopped, recommend checking INR at least weekly. It can take a month or longer for its effects to wear off.
- Linezolid (Zyvox) is usually saved for MRSA when other antibiotics can't be used due to its cost and toxicity.
- Advise patients they will need a weekly CBC lab test to detect possible bone marrow suppression. Get our note "Be alert for thrombocytopenia and neutropenia with linezolid".
- Also caution about combining linezolid with other serotonergic drugs (SSRIs, etc) due to possible serotonin syndrome.
- Clindamycin, minocycline, and beta-lactams. Are occasionally used for staph or strep. Look for GI problems especially with clindamycin.
NPS-adv
References
- Kim BN, Kim ES, Oh MD. Oral antibiotic treatment of staphylococcal bone and joint infections in adults. J Antimicrob Chemother. 2014;69(2):309-322.
- Osmon DR, Berbari EF, Berendt AR, et al. Diagnosis and management of prosthetic joint infection: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2013;56(1):e1-e25.
