Sierra Josep M, Martinez-Martinez Luis, Vázquez Fernando, Giralt Ernest, Vila Jordi
Department of Microbiology, School of Medicine, Hospital Clínic, IDIBAPS, University of Barcelona, Barcelona, Spain.
Antimicrob Agents Chemother. 2005 May;49(5):1714-9. doi: 10.1128/AAC.49.5.1714-1719.2005.
Quinolone susceptibility was analyzed in 17 clinical isolates of Corynebacterium striatum and 9 strains of Corynebacterium amycolatum by the E-test method in Mueller-Hinton agar plates. The C. striatum ATCC 6940 strain was used as a control strain. The amplified quinolone resistance determining regions of the gyrA genes of C. amycolatum and C. striatum were characterized. Four in vitro quinolone-resistant mutants of C. amycolatum were selected and analyzed. Both in vivo and in vitro quinolone-resistant strains of C. amycolatum showed high levels of fluoroquinolone resistance in strains with a double mutation leading to an amino acid change in positions 87 and 91 or positions 87 and 88 (unusual mutation) of GyrA, whereas the same concomitant mutations at amino acid positions 87 and 91 in GyrA of C. striatum produced high levels of resistance to ciprofloxacin and levofloxacin but only showed a moderate increase in the MIC of moxifloxacin, suggesting that other mechanism(s) of quinolone resistance could be involved in moxifloxacin resistance in C. amycolatum. Moreover, a PCR-RFLP-NcoI of the gyrA gene was developed to distinguish between C. amycolatum and C. striatum species.
采用E试验法在穆勒-欣顿琼脂平板上对17株纹带棒状杆菌临床分离株和9株无枝菌酸棒状杆菌进行喹诺酮敏感性分析。以纹带棒状杆菌ATCC 6940菌株作为对照菌株。对无枝菌酸棒状杆菌和纹带棒状杆菌gyrA基因的喹诺酮耐药决定区进行扩增并鉴定其特征。选取并分析了4株无枝菌酸棒状杆菌的体外喹诺酮耐药突变体。无枝菌酸棒状杆菌的体内和体外喹诺酮耐药菌株在GyrA的第87和91位或第87和88位（异常突变）发生导致氨基酸改变的双重突变时，显示出高水平的氟喹诺酮耐药性，而纹带棒状杆菌GyrA的第87和91位氨基酸发生相同的伴随突变时，对环丙沙星和左氧氟沙星产生高水平耐药，但莫西沙星的最低抑菌浓度仅适度增加，这表明无枝菌酸棒状杆菌对莫西沙星的耐药性可能涉及其他喹诺酮耐药机制。此外，还开发了一种gyrA基因的PCR-RFLP-NcoI方法来区分无枝菌酸棒状杆菌和纹带棒状杆菌。
