Staphylococcus Aureus Bacteremia Due to Central Venous Catheter Infection: A Clinical Comparison of Infections Caused by Methicillin-Resistant and Methicillin-Susceptible Strains

Background: Staphylococcus aureus ( S.aureus ) bacteremia has a mortality rate ranging from 20-40%. Central venous catheter (CVC) infection is the leading cause of S.aureus bacteremia. We investigated the differences in background characteristics, complications, and prognosis between patients with methicillin resistant S.aureus (MRSA) and methicillin sensitive S.aureus (MSSA) bacteremia due to CVC infection. Methods: We retrospectively investigated patients who had positive peripheral blood cultures versus positive semi-quantitative cultures for MRSA or MSSA from the CVC tip. We compared the clinical background characteristics, complications, and 60-day mortality rates between both groups. We analyzed our data using Mann-Whitney U test, chi-square test, and Fisher’s exact test. Results: This study had 17 (47%) and 19 (53%) MRSA and MSSA bacteremia patients, respectively. The median ages for MRSA and MSSA patients were 72 ± 27 and 55 ± 33 years, respectively (P<0.01). Comparison between baseline disease occurrence (MRSA vs. MSSA) was 10(59%) patients vs. 3(16%) patients (P=0.01), while complications included septic shock were 8(48%) vs. 3(16%) (P=0.07), respectively. The duration of catheter placement, time lag from onset of fever to CVC removal, and time lag from onset of fever to starting antimicrobial therapy were similar in both groups. Sixty-day mortality rates were 35%(6/17) vs. 5.3%(1/19), (P=0.04), in MRSA vs. MSSA groups, respectively. Conclusions: MRSA carriers and older patients were at a higher risk of MRSA CVC infection compared to MSSA bacteremia patients. MRSA bacteremia patients showed relatively higher rate of septic shock, and had significantly higher 60-day mortality rate despite appropriate antimicrobial therapy.