Bagge N, Ciofu O, Skovgaard L T, Høiby N
Department of Bacteriology, Institute of Medical Microbiology and Immunology, University of Copenhagen, Denmark.
APMIS. 2000 Sep;108(9):589-600. doi: 10.1034/j.1600-0463.2000.d01-102.x.
The aim of this study was to examine the development of resistance of biofilm-growing P. aeruginosa during treatment with ceftazidime. Biofilms were established in vitro using a modified Robbins device (MRD) and in vivo in the rat model of chronic lung infection. Three P. aeruginosa strains isolated from the lungs of cystic fibrosis (CF) patients (MICceftazidime-basal/induced beta-lactamase activity: PAO 579= 0.8 mg/l-19/550 milliunits, 19676A=50 mg/l-38/957 milliunits, 17107B=100 mg/l-504/947 milliunits) were studied. After 1 or 2 weeks of continuous or intermittent (4 h/day) administration of ceftazidime to biofilms established in MDR, a statistically significant development of resistance to ceftazidime in PAO 579 or 19676A bacterial populations occurred. When ceftazidime was administered 4 h/day (200 mg/l) for 2 weeks, the frequency of resistant 19676A having MIC>25 mg/l was 4.4 10(-1) compared to 6.0-10(-5) in the control biofilm. The same trend was observed after continuous administration of ceftazidime. MICceftazidime of the more resistant variants was increased 500-fold for PAO 579 and 8-fold for 19676A, and the specific basal beta-lactamase activities from 19 to 1,400 units for PAO 579 and from 38 to 10,000 units for 19676A. Chronic P. aeruginosa lung infection was established with alginate-embedded PAO 579, 19676A or 17107B in 146 Lewis rats which were treated with ceftazidime 4 g/kg intraperitoneally twice a day for 1 week. A statistically significant development of resistance was observed for all three strains. The MICceftazidime of the more resistant variants was increased 15-fold for PAO 579, 8-fold for 19676A, and 4-fold for 17107B, and the specific basal 3-lactamase activity from 19 to 100 units for PAO 579, from 38 to 1,300 units for 19676A, and from 500 to 1,300 units for 17107B. It was shown that, during treatment with ceftazidime, biofilm-growing P. aeruginosa had the capacity to develop resistance due to the production of chromosomal beta-lactamase.
本研究的目的是检测在使用头孢他啶治疗期间，生物被膜生长的铜绿假单胞菌的耐药性发展情况。使用改良的Robbins装置（MRD）在体外建立生物被膜，并在慢性肺部感染的大鼠模型中在体内建立生物被膜。研究了从囊性纤维化（CF）患者肺部分离出的三株铜绿假单胞菌（头孢他啶基础/诱导β-内酰胺酶活性的最低抑菌浓度：PAO 579 = 0.8 mg/l - 19/550毫单位，19676A = 50 mg/l - 38/957毫单位，17107B = 100 mg/l - 504/947毫单位）。在向MDR中建立的生物被膜连续或间歇（每天4小时）给予头孢他啶1或2周后，PAO 579或19676A细菌群体中对头孢他啶的耐药性出现了统计学上显著的发展。当每天4小时（200 mg/l）给予头孢他啶2周时，19676A中最低抑菌浓度>25 mg/l的耐药菌频率为4.4×10⁻¹，而对照生物被膜中为6.0×10⁻⁵。连续给予头孢他啶后也观察到了相同的趋势。PAO 579中耐药性更强的变体的头孢他啶最低抑菌浓度增加了500倍，19676A增加了8倍，PAO 579的特定基础β-内酰胺酶活性从19单位增加到1400单位，19676A从38单位增加到10000单位。用藻酸盐包埋的PAO 579、19676A或17107B在146只Lewis大鼠中建立慢性铜绿假单胞菌肺部感染，每天两次腹腔注射4 g/kg头孢他啶，持续1周。所有三株菌株均观察到耐药性有统计学上显著的发展。PAO 579中耐药性更强的变体的头孢他啶最低抑菌浓度增加了15倍，19676A增加了8倍，17107B增加了4倍，PAO 579的特定基础β-内酰胺酶活性从19单位增加到100单位，19676A从38单位增加到1300单位，17107B从500单位增加到1300单位。结果表明，在使用头孢他啶治疗期间，生物被膜生长的铜绿假单胞菌由于产生染色体β-内酰胺酶而具有产生耐药性的能力。
