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Volume 45, Number 2, April 2012

A multicenter surveillance of antimicrobial resistance on Stenotrophomonas maltophilia in Taiwan

Hsiu Wu, Jen-Tay Wang, Yih-Ru Shiau, Hui-Yin Wang, Tsai-Ling Yang Lauderdale*, han-Chwen Chang, TSAR Hospitals

Received: March 31, 2011    Revised: May 17, 2011    Accepted: June 29, 2011   


Corresponding author:

Tsai-Ling Yang Lauderdale, Division of Infectious Diseases, National Health Research Institutes, 35 Keyan Road, Zhunan, 350 Taiwan.
E-mail address: (T.-L. Yang Lauderdale).


Background and purpose: 

Stenotrophomonas maltophilia has emerged as an important opportunistic pathogen in debilitated hosts. Clinical management of S. maltophilia is challenging due to its intrinsic resistance to a variety of antibiotics. This study investigated the trend and prevalence of antimicrobial resistance in S. maltophilia from a nationwide surveillance study in Taiwan.



S. maltophilia isolates were collected biennially between 1998 and 2008 as part of the Taiwan Surveillance of Antimicrobial Resistance (TSAR) program from medical centers and regional hospitals throughout Taiwan. Minimal inhibitory concentrations (MIC) were determined using the Clinical and Laboratory Standards Institute reference broth microdilution method



A total of 377 non-duplicate S. maltophilia isolates were collected from 38 hospitals. The majority of the isolates were from the respiratory tract (256, 67.9%), followed by blood (48, 12.7%). Overall, 376 (99.7%) isolates were susceptible to minocycline, 362 (96%) to tigecycline, 311 (82.5%) to trimethoprim/sulfamethoxazole (TMP-SMX), 300 (79.6%) to levofloxacin, 92 (24.4%) to ceftazidime, and 70 (18.6%) to ticarcillin-clavulanic acid. The MIC50/MIC90 of minocycline, tigecycline, TMP-SMX, levofloxacin, ceftazidime, and ticarcillin-clavulanic acid, were  0.5/1 mg/mL, 0.25/1 mg/mL,  0.25/8 mg/mL, 1/4 mg/mL, 32/128 mg/mL, and 64/128 mg/mL, respectively. A trend of increased non-susceptibility to levofloxacin
(pZ0.014) was observed over the 10-year study period. Compared to TMP-SMX-susceptible isolates, TMP-SMX-resistant isolates were less susceptible to levofloxacin (54.5% vs. 84.9%, p < 0.001).



In this 10-year study, minocycline and TMP-SMX remained the two antimicrobials with better in vitro activities against S. maltophilia than ceftazidime, levofloxacin, and ticarcillin-clavulanic acid. The activity of levofloxacin against S. maltophilia in Taiwan declined during the past 10 years.


Key words:

Antimicrobial resistance; Minimal inhibitory concentration; Stenotrophomonas maltophilia; Surveillance; Surveillance of Antimicrobial Resistance (TSAR); Taiwan