Graduate Institute of Clinical Medical Sciences, Chang Gung University College of Medicine, Taoyuan, Taiwan.
Int J Antimicrob Agents. 2010 Apr;35(4):382-6. doi: 10.1016/j.ijantimicag.2009.12.009. Epub 2010 Feb 6.
Nosocomial infections caused by multidrug-resistant (MDR) Acinetobacter baumannii have been increasing in recent years, posing a threat to public health worldwide. The susceptibility to eight antimicrobial agents of 35 clinical A. baumannii isolates from Taiwan was tested. Isolates were examined by polymerase chain reaction (PCR) and sequencing for beta-lactamase genes and mutations in the gyrA and parC genes. Expression of AdeB, an efflux pump protein, was evaluated by real-time quantitative PCR. The level of adeB expression correlated with resistance to ciprofloxacin and ampicillin/sulbactam in A. baumannii isolates. Almost all isolates with full resistance to ciprofloxacin had both high adeB expression and point mutations in parC and gyrA, but 4 intermediate-resistant isolates had only high adeB expression without point mutations in gyrA or parC, in contrast to 18 susceptible isolates with low adeB expression and without mutations in gyrA or parC. Sixteen isolates (45.7%) carrying a type 1 integron were MDR as well as being more resistant to imipenem, amikacin, gentamicin, ceftazidime or cefepime than those without the integron. The class 1 integron in A. baumannii carried different resistance gene cassettes, including 5'CS-bla(IMP-1)-aadA4-3'CS, 5'CS-aacA4-aadA1-3'CS and 5'CS-aacC1-aadA1-3'CS. In conclusion, expression of the adeB gene was associated with resistance to ciprofloxacin and ampicillin/sulbactam in A. baumannii. Multiple mutations in gyrA and parC also played a role in ciprofloxacin resistance. The major metallo-beta-lactamase contributing to imipenem resistance in A. baumannii in Taiwan was bla(IMP-1), which was carried by the class 1 integron. The class 1 integron was associated with the MDR phenotype in A. baumannii.
近年来，耐多药（MDR）鲍曼不动杆菌引起的医院感染不断增加，对全球公共健康构成威胁。检测了来自台湾的 35 株临床鲍曼不动杆菌分离株对 8 种抗菌药物的敏感性。通过聚合酶链反应（PCR）和测序检测β-内酰胺酶基因和 gyrA 和 parC 基因的突变。通过实时定量 PCR 评估 AdeB，一种外排泵蛋白的表达。A. baumannii 分离株中 adeB 表达水平与对环丙沙星和氨苄西林/舒巴坦的耐药性相关。几乎所有对环丙沙星完全耐药的分离株均具有高 adeB 表达和 parC 和 gyrA 中的点突变，但 4 株中度耐药的分离株仅具有高 adeB 表达，而 gyrA 或 parC 中没有点突变，而 18 株敏感的分离株则具有低 adeB 表达，且 gyrA 或 parC 中没有突变。携带 1 型整合子的 16 株（45.7%）对亚胺培南、阿米卡星、庆大霉素、头孢他啶或头孢吡肟的耐药性也高于无整合子的分离株。鲍曼不动杆菌中的 1 类整合子携带不同的耐药基因盒，包括 5'CS-bla(IMP-1)-aadA4-3'CS、5'CS-aacA4-aadA1-3'CS 和 5'CS-aacC1-aadA1-3'CS。总之，adeB 基因的表达与 A. baumannii 对环丙沙星和氨苄西林/舒巴坦的耐药性有关。gyrA 和 parC 的多重突变也在环丙沙星耐药中起作用。台湾鲍曼不动杆菌对亚胺培南耐药的主要金属β-内酰胺酶是 bla(IMP-1)，它由 1 类整合子携带。1 类整合子与 A. baumannii 的 MDR 表型有关。
