Vol.61 No.2 March 2013

A study of the usage of antibiotics and hand disinfectants and their effect on methicillin-resistant Staphylococcus aureus isolation rates

Toshiko Konishi¹⁾, Aeko Goto²⁾, Yuji Hirai³⁾, Yusuke Ainoda³⁾, Takahiro Fujita³⁾, Toshimi Kimura¹⁾ and Kyoichi Totsuka³⁾

¹⁾Department of Pharmacy, Tokyo Women's Medical University Hospital, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, Japan
²⁾Department of Clinical Laboratory, Tokyo Women's Medical University Hospital
³⁾Department of Infectious Disease, Tokyo Women's Medical University

Abstract

Methicillin-resistant Staphylococcus aureus(MRSA) is an important pathogenic bacterium causing nosocomial infections, accounting for 67% and 55% of all S. aureus isolates in Japan in 2004 and 2011, respectively. MRSA bacteremia is associated with a high mortality rate and is difficult to treat; therefore, the control and treatment of MRSA infections with antibiotics is important. Using data from patients hospitalized between April 2004 and March 2012, we examined how the use of antibiotics and hand disinfectants affected the MRSA isolation rates.
The prevalence of MRSA among S. aureus isolates from all the samples and blood culture samples (hereinafter referred to as the MRSA isolation rate) decreased from 43.5% and 60.6% in 2004 to 31.9% and 40.6% in 2011, respectively. The antimicrobial usage density (AUD) and the MRSA isolation rates from all the samples and blood culture samples were correlated for first-generation cephalosporins (r=-0.90, -0.99), penicillin antibiotics (r=-0.87, -0.82), glycopeptide antibiotics (r=-0.84, -0.86), and alcohol-based hand rub (ABHR)(r=-0.77, -0.89); the MRSA isolation rates decreased with the increased use of the above-mentioned antibiotics/disinfectants. In addition, as the use of second-generation cephalosporins (r=0.85, 0.91) decreased, the MRSA isolation rates also decreased. The AUDs of vancomycin and third-generation cephalosporins, which are correlated with the MRSA isolation rates, both increased. However, the AUD of the third-generation cephalosporins per total amount of the AUD was approximately 10%. The low comparative use of antibiotics did not affect the increase in the MRSA isolation rates. The AUDs of the first-generation cephalosporins and penicillin antibiotics increased by more than 60%. Our results suggested that the increasing AUDs of narrow-spectrum antibiotics might reduce the MRSA isolation rates. The use of ABHR, which has increased across institutions, appears to be strongly associated with the MRSA isolation rates. Improved hand hygiene after in-hospital education and the prevention of horizontal transmission through the use of infection control measures according to the infection transmission routes may also have contributed to the decrease in the number of patients with newly identified MRSA cultures. We consider it important to continue the implementation of hospital-wide infection control programs and antimicrobial stewardship, mainly by infection control teams.

Key word

MRSA, antimicrobial use density (AUD), alcohol-based hand-rub, antimicrobial stewardship, ICT

Received

October 22, 2012

Accepted

February 1, 2013

Jpn. J. Chemother. 61 (2): 162-170, 2013