JAC Advance Access published online on June 11, 2009
Journal of Antimicrobial Chemotherapy, doi:10.1093/jac/dkp209
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Original research |
Antimicrobial susceptibility of Streptococcus pneumoniae at a university hospital in Taiwan, 2000–07: impact of modified non-meningeal penicillin breakpoints in CLSI M100-S18
1 Department of Laboratory Medicine, Chang Gung Memorial Hospital, 5 Fu-Hsin Street, Kweishan, Taoyuan 333, Taiwan 2 Chang Gung University College of Medicine, 259 Wenhua 1st Road, Kweishan, Taoyuan 333, Taiwan 3 Division of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Children's Hospital, 5 Fu-Hsin Street, Kweishan, Taoyuan 333, Taiwan
Received 22 September 2008; returned 30 December 2008; revised 15 April 2009; accepted 26 May 2009
* Corresponding author. Tel: +886-3-3281200, ext. 8896; Fax: +886-3-3288957; E-mail: chchiu{at}adm.cgmh.org.tw
Objectives: In 2008, a new set of penicillin breakpoints was published in the CLSI revised guideline, M100-S18, to define the susceptibility of non-meningeal isolates of Streptococcus pneumoniae. The impact of the change is studied and discussed.
Methods: Laboratory data on pneumococcal isolates collected from Chang Gung Memorial Hospital during 2000–07 were analysed using the original and modified penicillin CLSI breakpoints.
Results: A total of 3729 non-duplicate isolates were identifed, including 43 (1.2%) meningeal isolates showing high rates of penicillin (79.1%) and ceftriaxone (34.9%) resistance. For non-meningeal isolates, penicillin non-susceptibility was reduced significantly from 75.1% (72.4% in 2000–03 increasing to 77.4% in 2004–07) to 16% (28.6% in 2000 decreasing to 2.4% in 2007) if the modified breakpoints were applied. However, isolates for which penicillin MICs were 1–2 mg/L increased significantly from 34.2% in 2000 to 59.8% in 2007. Ceftriaxone non-susceptibility also increased significantly from 2.8% before 2005 to 18.4% thereafter. A quarter (25.7%) of the pneumococcal isolates were recovered from patients <10 years old. Higher resistance to penicillin (89.8% versus 70.4%; or 19.1% versus 13.2% by the modified breakpoints) or ceftriaxone (11.1% versus 5.8%) was found among these isolates, compared with those from older patients.
Conclusions: With the implementation of the new breakpoints, clinicians may continue to use penicillin for the treatment of non-meningeal pneumococcal infections in preference to other drug classes. However, as isolates with borderline penicillin MICs are increasing, continued surveillance of pneumococcal susceptibility to penicillin will be needed.
Key Words: clinical outcomes , pneumococcal infections , ceftriaxone resistance
These authors contributed equally to this work.