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

Abstract

Background. Bacteremia due to Staphylococcus aureus has been associated with mortality rates of 15-60%. Central venous catheter(CVC) infection is a major cause of healthcare associated MRSA bacteremia, which is a growing problem. We investigated the differences in clin features and mortality rates for patients who have methicillin- resistant S.aureus(MRSA) bacteremia compared with methicillin-susceptible S.aureus(MSSA) bacteremia secondary to CVC infection. Methods. We retrospectively investigated all the patients who showed positive for MRSA or MSSA from peripheral blood cultures and also positive from semiquantitative cultures of CVC tip taken on the same or near date from Aug 2004 to Mar 2016 at St Luke's Intl Hosp(530 beds acute care hosp, inTokyo). We included the patients who were aged over 15, with sufficient medical records and did't have other primary infections.We analyzed the consecutive 36 patients with S.aureus bacteremia due to CVC infection. We compared the characteristics, therapy, complications and 60 day mortality rate of the MRSA patients and MSSA patients. Mann-Whitney U test, chisquare test, Fisher test were used for analysis. Results. There were 17 MRSA patients(47%) and 19 MSSA patients(53%). Median age 72(SD27) in MRSA patients, 55(33) in MSSA patients, P < 0.01. Underlying diseases of the MRSA patients vs the MSSA patients:MRSA carrier 10(59%) vs 3(16%), P = 0.01, Diabetes 3(18%) vs 5(26%), P = 0.70, Malignancy 2(12%) vs 5(26%), P = 0.41, Renal diseases 4(24%) vs 7(37%), P = 0.48, SteroidUse 8(48%) vs 4(22%), P = 0.16, TPN 10(60%) vs 4(22%), P = 0.16. Complications of the MRSA patients vs the MSSA patients:Septic shock 8(48%) vs 3(16%), P = 0.07, Endocarditis 0(0%) vs 2(11%), P = 0.49, Duration of catheter placement: MRSA patients 13.5 days (SD 8) vs MSSA patients 9.5 days (20), P = 0.58, Time lag from onset to CVC removal: MRSA patients <1 day vs MSSA patients 1.0 day, P = 0.71. Time lag from onset to start effective antibiotics( In all MRSA patients vancomycin was started.): MRSA patients<1day vs MSSA patients<1day, P = 0.7, 60day mortality rate was MRSA patients:6/17(35%) vs MSSA patients:1/19(5.3%), P = 0.04. Conclusion. Patients with MRSA carrier and old age might have higher risk of MRSA CVC infection. MRSA patients might have higher risk of septic shock (48%) and showed significantly higher 60 day mortality rate (35%) compared with MSSA patients (5.3%) in spite of appropriate therapy. (Table Presented).