Acinetobacter baumannii 對fluoroquinolones抗藥性菌株之分子流行病學分析及抗藥性機轉研究
Other Title
Molecular Epidemiology and Clinical Characteristics of Fluoroquinolones-
Resistant Acinetobacter baumannii in Taiwan
Resistant Acinetobacter baumannii in Taiwan
Date Issued
2003
Date
2003
Author(s)
張上淳
DOI
912314B002167
Abstract
Acinetobacter baumannii is a new emerging nosocomial pathogen since 1990s. It
is usually highly resistant to various antibiotics and difficult to treat. The yearly
surveillance of nosocomial infection at National Taiwan University Hospital (NTUH)
showed A. baumannii infections increased from 2% to 5% in last decade.
Fluoroquinolones have once shown good activities against A. baumannii in early 1990s,
however, decreased susceptibilities of fluoroquinolones had been reported recently.
In this study, clinical fluoroquinolone-resistant isolates of A. baumannii preserved
between 1992 and 2002 at NTUH laboratory and isolates from various hospitals
preserved at National Health Research Institute (NHRI) collected during 1998 to 2000
were analyzed. Minimum inhibitory concentrations (MICs) of fluoroquinolones by agar
dilution method and pulsed-field gel electrophoresis (PFGE) analysis of FQs-resistant
isolates were performed. The MIC50 and MIC90 of ciprofloxacin of A. baumannii
isolated before1997at NTUH were 0.5 µg/mL and 8 µg/mL (range, 0.06-≥128µg/mL)
and 22% of the isolates were ciprofloxacin-resistant. However, the MIC50 and MIC90
had elevatedto 2µg/mL and 64µg/mL in 2002 with 47% of isolates were
ciprofloxacin-resistant. The same circumstances were similar among other
fluoroquinolones. Ciprofloxacin-resistant A. baumannii isolates were also
cross-resistant to other fluoroquinolones frequently; norfloxacin (100%), ofloxacin
(98%), levofloxacin (94%), gatifloxacin (93%) and moxifloxacin (88%). Secular
surveillance (1997 to 2002) revealed a trend of increasing high-level
fluoroquinolones-resistance (ciprofloxacin) for A. baumannii during recent years and
correlated with increasing use of fluoroquinolones. Totally 80 of 174 isolates (46%) of
A. baumannii from NHRI were fluoroquinolones-resistant (ciprofloxacin MICs ≧4
µg/mL); MIC50, 2µg/mL; MIC90, 32 µg/mL; ranged from 0.25-≥128µg/mL. Pulsed field gel electrophoresis (PFGE) of these isolates was performed and clonal spread within
hospital or between hospitals (region), especially of A. baumannii with high-level
FQs-resistance (ciprofloxacin MICs ≧64 µg/mL) was noted. The same PFGE pattern of
A. baumannii isolates with different MICs suggested the resistance of fluoroquinolone
were developed step by step. We further investigated the mechanisms of
fluoroquinolone-resistance by analysis the sequence of DNA gyrase (topoisomerase II,
gyr A) and topoisomerase IV (par C). No changes of aminoacid (gyr A: Gly 81, Ser 83,
Ala 84; par C: Ser 80, Glu 84) of quinolone-resistance determination region (QRDR) of
these isolates were detected. The actual mechanisms of fluoroquinolone-resistance in A.
baumannii in Taiwan needed further investigation.
In conclusion, the wide spread use of fluoroquinolones in Taiwan has resulted in
the emergence and subsequent increase of fluoroquinolone-resistance, at rates greater
than was anticipated. Spreading of high-level fluoroquinolone-resistant clones in recent
years compatible with increasing use of fluoroquinolones. It is important that
continuous infection control and prudent use of these agents (selective pressure) be
emphasized, not only treatment of human bacterial infections but also veterinary
medicine to prevent the emergence and increase of resistant strains.
Subjects
fluoroquinolones
molecular epidemiology
polymerase chain reaction (PCR)
pulsed-field gel electrophoresis (PFGE)
SDGs
Publisher
臺北市：國立臺灣大學醫學院內科
Type
report
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