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Volume 47, Number 1, February 2014

Methicillin-resistant Staphylococcus aureus bacteremia in hemodialysis and nondialysis patients 


Li-Ping Kan, Jung-Chung Lin, Sheng-Kang Chiu, Yen-Cheng Yeh, Te-Yu Lin, Ya-Sung Yang, Yung-Chih Wang, Ning-Chi Wang, Kuo-Ming Yeh, Feng-Yee Chang


Received: April 30, 2012    Revised: July 31, 2012    Accepted: August 15, 2012   

 

Corresponding author:

Kuo-Ming Yeh, Corresponding author. Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, No. 325 Cheng-Kung Road, Section 2, Nei-hu, Taipei 114, Taiwan. 



 

Background and purpose: 

Increased mortality has been reported in patients treated with vancomycin for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia with high minimum inhibitory concentration (MIC) values within the susceptibility range. However, this finding has not been verified in hemodialysis patients, who have much higher invasive MRSA infection rates than nondialysis patients. We aimed at comparing vancomycin MICs between hemodialysis and nondialysis patients, and identifying predictors of high vancomycin MICs and infection-related mortality in hemodialysis patients with MRSA bacteremia.
 



 

Methods:

Patients with MRSA bacteremia from January 2008 through December 2009 were enrolled. Vancomycin MIC was determined for each first isolate using the Etest method. Clinical characteristics and vancomycin MICs were compared between hemodialysis and nondialysis patients. Factors associated with high vancomycin MIC (2 μg/mL) and infection-related mortality in hemodialysis patients were analyzed.
 



 

Results:

A total of 162 MRSA bacteremia episodes were identified. Forty-four (27.0%) isolates were obtained from hemodialysis patients and 118 (73.0%) from nondialysis patients. Diabetes (63.3% vs. 39.8%, p = 0.007) and prior vancomycin exposure in 30 days (31.8% vs. 12.7%, p = 0.005) were more prevalent in hemodialysis group than in nondialysis group. A higher prevalence of vancomycin MIC of 2 μg/mL was observed in hemodialysis group in comparison with nondialysis group (11.4% vs. 1.7%, p = 0.016). In following analyses of hemodialysis group, patients with initial presentation of septic shock had a higher risk of vancomycin MIC of 2 μg/mL than nonseptic shock patients (100.0% vs. 38.5% p = 0.014). Infection-related mortality was associated with age, Acute Physiology and Chronic Health Evaluation II (APACHE-II) score >15, presence of septic shock, receipt of mechanical ventilation, and failure to remove source of bacteremia in univariate analysis. 



 

Conclusion:

Hemodialysis patients with MRSA bacteremia are more likely to have a high vancomycin MIC (2 μg/mL) compared with nondialysis patients. Infection-related mortality is associated with the patient's clinical manifestations, including age, APACHE-II score >15, presence of septic shock, receipt of mechanical ventilation, and failure to remove source of bacteremia. Treatment selection should be tailored according to the patient's clinical condition.



 

Key words:

Bacteremia, Hemodialysis, Methicillin-resistant Staphylococcus aureus, Minimum inhibitory concentration