Department of Laboratory Medicine, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania.
Medicina (Kaunas). 2011;47(7):361-7.
The aim of our study was to determine the changes in antibiotic resistance and O serogroup dependence of P. aeruginosa strains isolated from lower respiratory tract specimens of patients in 2003 and 2008; the patients were treated in intensive care units of the biggest treatment facility in Lithuania (Hospital of Lithuanian University of Health Sciences, HLUHS, former Hospital of Kaunas University of Medicine)
The study included 90 P. aeruginosa strains serotyped in 2003 and 101 P. aeruginosa strains serotyped in 2008, which were randomly selected. The resistance of P. aeruginosa strains was determined by the disc diffusion method based on the standard guidelines. The sizes of inhibition zones were interpreted according to the National Committee for Clinical Laboratory Standards (M(2)-A(6)). Isolates were serotyped using sera with specific antibodies against the O antigens of P. aeruginosa (Bio-Rad, France).
Comparison of changes in the distribution of P. aeruginosa serogroups in 2003 and 2008 showed that P. aeruginosa strains of serogroups O:1, O:2, and O:3 were more prevalent in 2003 as compared with 2008 (23.3%, n=21; 27.8%, n=25; 12.2%, n=11 vs. 9.9%, n=10; 10.9%, n=11; 4.0%, n=4, P<0.05). P. aeruginosa strains of serogroups O:6 and O:11 were isolated more frequently in 2008 than 2003 (26.7%, n=27; 34.7%, n=35 vs. 4.4%, n=4; 10.0%, n=9, P<0.001). The results showed that 18 of the 90 P. aeruginosa strains in 2003 and 25 of the 101 P. aeruginosa strains in 2008 were resistant to three or more antibiotics tested, i.e., they were multidrug-resistant. Analysis of the distribution of serogroups among these P. aeruginosa strains isolated in 2003 and 2008 revealed a significantly higher frequency of O:11 serogroup than other serogroups. Meanwhile, in the group of nonmultidrug-resistant P. aeruginosa strains, P. aeruginosa O:11 serogroup strains were identified less frequently and accounted only for 2.8% (n=2, P<0.001) of the isolates in 2003 and 27.6% (n=21, P<0.01) in 2008.
During the 5-year period, the isolation rate of P. aeruginosa strains belonging to serogroup O:11 increased. P. aeruginosa strains isolated in 2003 and 2008 belonging to serogroup O:11 were more frequently multidrug resistant. The increasing resistance of P. aeruginosa to reserve antibiotics of carbapenem group was observed.
本研究旨在确定 2003 年和 2008 年从立陶宛最大治疗机构（立陶宛健康科学大学医院，前身为考纳斯医科大学医院）重症监护病房患者下呼吸道标本中分离的铜绿假单胞菌菌株的抗生素耐药性和 O 血清群依赖性变化。
本研究纳入了 2003 年随机选择的 90 株铜绿假单胞菌血清型和 2008 年随机选择的 101 株铜绿假单胞菌血清型。采用基于标准指南的纸片扩散法测定铜绿假单胞菌的耐药性。根据国家临床实验室标准委员会（M2-A6），根据抑菌环大小来解释结果。使用针对铜绿假单胞菌 O 抗原的特异性抗体血清对分离株进行血清分型（Bio-Rad，法国）。
2003 年和 2008 年铜绿假单胞菌血清群分布变化的比较表明，2003 年 O:1、O:2 和 O:3 血清群的铜绿假单胞菌菌株比 2008 年更为常见（23.3%，n=21；27.8%，n=25；12.2%，n=11 比 9.9%，n=10；10.9%，n=11；4.0%，n=4，P<0.05）。2008 年 O:6 和 O:11 血清群的铜绿假单胞菌菌株比 2003 年分离更为频繁（26.7%，n=27；34.7%，n=35 比 4.4%，n=4；10.0%，n=9，P<0.001）。结果显示，2003 年的 90 株铜绿假单胞菌中有 18 株和 2008 年的 101 株铜绿假单胞菌中有 25 株对三种或三种以上测试的抗生素耐药，即它们为多药耐药菌。对 2003 年和 2008 年分离的这些铜绿假单胞菌菌株的血清群分布进行分析，发现 O:11 血清群的频率显著高于其他血清群。同时，在非多药耐药铜绿假单胞菌菌株组中，2003 年 O:11 血清群铜绿假单胞菌菌株的鉴定频率较低，仅占 2.8%（n=2，P<0.001），而 2008 年为 27.6%（n=21，P<0.01）。
在 5 年期间，属于 O:11 血清群的铜绿假单胞菌菌株的分离率增加。2003 年和 2008 年分离的属于 O:11 血清群的铜绿假单胞菌菌株更常为多药耐药菌。观察到铜绿假单胞菌对碳青霉烯类抗生素储备药物的耐药性不断增加。
