Staphylococcus aureus bacteremia in patients receiving pegylated interferon-alpha and ribavirin for chronic hepatitis C virus infection.

Bacteremia has rarely been reported in patients receiving treatment for hepatitis C virus (HCV) infection. We describe the features and investigation of four cases of Staphylococcus aureus bacteremia occurring between 3 November 2004 and 10 January 2005 in patients on therapy for chronic HCV infection. The unusual occurrence of S. aureus bacteremia in a series of patients led to an epidemiologic investigation and molecular typing methods were employed to assess the relatedness of cases. The mean time of bacteremia onset was week 10 of HCV treatment. No patient had neutropenia previously. The average duration of bacteremia was 2.6 days and complications included acute renal failure (2/4), disseminated intravascular coagulopathy (DIC) with sepsis syndrome (1/4), septic arthritis (1/4), spinal epidural abscess (1/4) and endocarditis (1/4). Two patients were in the same weight class for dosing, but no other epidemiologic links were found. One patient admitted to intravenous drug use (IVDU) and a second was suspected of IVDU. The two other patients were cirrhotic, but had no further identifiable risk factors. All bacterial isolates were methicillin-susceptible. By pulsed-field gel electrophoresis, two cases were found to have identical bacterial strains. However, fluorescent-based amplified fragment-length polymorphism analysis demonstrated distinct band patterns in all four cases. The epidemiologic data and molecular analysis of this cluster of S. aureus bacteremia cases among patients receiving combination therapy for treatment of chronic HCV infection suggest that these cases were not related. Additionally, IVDU and cirrhosis, but not neutropenia, are identified as potential risk factors for this uncommon complication of HCV therapy.