Download Title: CHARACTERIZATION OF METHICILLIN

Title: CHARACTERIZATION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS BACTEREMIA AND
REDUCED DAPTOMYCIN MIC WITHIN THE SUSCEPTIBLE RANGE
Category: Resistencia bacteriana e infecciones por microorganismos resistentes
Authors: BARDOSSY A.C.(1), RIZVI K.(1), MISIKIR H.(1), REHMAN T.(1), FAROOQUI Z.(1), NIAZY A.(1),
OSBORN Z.(1), PERRI M.(1), ZERVOS M(1).
(1) Infectious Disease Division, Henry Ford Health System, Detroit, Michigan, USA.
Responsible author:
Ana Cecilia Bardossy
Henry Ford Health System
2799 W Grand Blvd, Detroit, MI 48202, USA
Email: [email protected]
Cell phone: +1 248 550 7792
Introduction
The use of daptomycin as an alternative agent for methicillin-resistant Staphylococcus aureus (MRSA)
bloodstream infections (BSI) has increased, however daptomycin resistance remains uncommon. We
describe clinical characteristics of patients with MRSA BSI with low and high daptomycin MIC, within the
susceptible range.
Methods
A retrospective cohort study was conducted from 1/2016 to 9/2016 in a health system in Michigan.
Electronic medical records of patients with MRSA BSI were reviewed for clinical and laboratory data.
Patients without daptomycin susceptibility performed were excluded. Vancomycin and daptomycin MICs
were determined by Etest. Low daptomycin MIC was defined as <1 µg/ml and high MIC as 1 µg/ml.
Results
A total of 109 patients were evaluated, 10 (9.2%) had daptomycin MIC of 1 µg/ml. The average age of
patients with low MIC was 49.6 vs 60.8 years with high MIC (p 0.04). In the low and high MIC groups BSI
duration was 2.6 vs 4.6 days respectively. Three months prior exposure to vancomycin in low and high
groups was 26.3% and 50% (p 0.11); three months prior daptomycin exposure in low and high groups was
6.1% and 30% (p 0.009). One year prior MRSA infection was 12.2% in the low MIC group vs 50% in the
high MIC group (p 0.001). The mean vancomycin MIC was 1.06±0.31 in the low MIC group vs 1.23±0.45 in
the high MIC group (p 0.14). The 30-day all-cause mortality was 23.9%.
Conclusion
Patients with prior exposure to daptomycin and history of MRSA infection had higher daptomycin MIC.