MRSA clinical trials

Epidemiology and Treatment of Small-colony Variant Staphylococcus Aureus in Cystic Fibrosis

Methicillin-susceptible (MSSA) and Methicillin-resistant (MRSA) Staphylococcus aureus (SA) are two of the most important infectious pathogens in CF, with 69% of CF patients having lung infection with MSSA or MRSA in the last year. Wolter and co-workers recently demonstrated that a specific morphologic subtype of MSSA and MRSA, small-colony variant Staph aureus (SCV-SA), is associated with greater decline in lung function and worse clinical outcomes. SCV-SA is already recognized for its ability to contribute to persistent infection, likely due to SCV-SA's ability for intracellular growth, as well as its increased antibiotic resistance compared to normal-colony SA. To investigate the epidemiology and clinical significance of SCV-SA in CF, and explore the hypothesis that SCV-SA may require unique antibiotic treatment strategies to optimize clinical response, the investigators will perform the following: 1. Characterize the epidemiology of SCV-SA infection in both an adult and pediatric CF population and investigate the clinical significance of SCV-SA infection in CF by comparing clinical characteristics and outcomes of CF patients with SCV-SA compared to those with to normal-colony MSSA/MRSA. 2. Characterize the unique microbiologic characteristics of SCV-SA infection in CF by evaluating antibiotic susceptibility profiles and molecular characteristics of SCV-SA in a two large CF patient populations. 3. Perform a 16-patient pilot study of a novel treatment for SCV-SA infection in CF, utilizing low dose rifampin in combination with standard anti-SA antibiotics. These investigations will delineate the role of SCV-SA as a pathogen in CF and provide guidance to optimize treatment strategies of MSSA/MRSA CF lung infection.