TABLE 3.

Adverse effects of rifampin for cases and controls

Characteristic or effect	Value for group		P value
	Cases	Controls
Total no. of subjects	42	42
Rifampin-resistant isolates [no. (%)]a	9 (21)	0 (0)	<0.001
Median time to rifampin resistanceb [days (range)]	16 (11-26)	NAd	NA
Elevated transaminases, ≥5 × baseline [no. (%)]	9 (21)	1 (2)	0.014
Drug interactions [no. (%)]c	22 (52)	0 (0)	<0.001

^aAll nine isolates were from patients who were bacteremic at initiation of rifampin treatment.

^bNine isolates were analyzed.

^cDrug interactions occurred with methadone (nine cases), warfarin (four cases), protease inhibitors (three cases), antifungal agents (e.g., fluconazole [three cases], voriconazole [one case]), and antiepileptic agents (e.g., phenytoin [two cases]).

^dNA, not applicable.