Hypokalemia during antibiotic treatment for bone and joint infections.

PURPOSE: During treatment of bone and joint infections (BJIs) with multiple antibiotic therapy, hypokalemia has been reported as a rare side effect. The aim of this study was to evaluate incidence and risk factors for hypokalemia in a cohort of patients treated with multidrug therapy for BJIs, in a single center.

METHODS: We retrospectively reviewed 331 clinical files of 150 consecutive patients (65% males; median age 59 years, 95% CI 55-62) admitted repeatedly to our Osteomyelitis Department for treatment of chronic BJIs. Besides surgical debridement, patients received a combination of oral and intravenous antibiotics. Routine laboratory tests were performed at admittance and repeated at least weekly. Possible hypokalemia risk factors were recorded and analyzed.

RESULTS: Progressive kalemia reduction occurred in > 39% of patients during hospitalization; prevalence of marked hypokalemia (K +  < 3.5 mEq/l) increased from 5% at admission to 11% (up to 22%) at day 14. Correlated factors were: age ≥ 68 years (p = 0.033), low serum albumin (p = 0.034), treatment with vancomycin (p < 0.001), rifampicin (p = 0.017) and ciprofloxacin (p < 0.001) and use of thiazide (p = 0.007) or loop diuretics (p = 0.029 for K +  < 3.5 mEq/l). At multivariate regression analysis, the main determinants of hypokalemia were simultaneous use of diuretics (p = 0.007) and older age (p < 0.049).

CONCLUSIONS: Appearance of severe hypokalemia is a frequent event among patients treated for BJIs with multiple antibiotic therapy, when this is prescribed in older age patients and associated with simultaneous use of diuretics. Due to possible increase in mortality risk in the short term, particular caution should be paid during intensive antibiotic treatment in these groups of patients.