Lucena Andréa, Dalla Costa Libera M, Nogueira Keite da Silva, Matos Adriana P, Gales Ana C, Raboni Sonia M
Post-Graduate Program in Internal Medicine and Health Sciences, Universidade Federal do Paraná, Curitiba, Brazil.
Bacteriology Laboratory, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, Brazil; Faculdades e Instituto de Pesquisa Pelé Pequeno Príncipe, Curitiba, Paraná, Brazil.
Enferm Infecc Microbiol Clin. 2014 Dec;32(10):625-30. doi: 10.1016/j.eimc.2014.03.015. Epub 2014 Jun 6.
Metallo-β-lactamase (MBL)-producing gram-negative bacteria are an increasing public health concern worldwide. Screening tests for the rapid and specific identification of these pathogens are essential, and should be included among routine diagnostics in laboratories. This study aimed to determine the MBL frequency among carbapenem-resistant Pseudomonas aeruginosa isolates, and to evaluate the accuracy of different tests in screening for MBL production. From January 2001 to December 2008, a total of 142 imipenem-non-susceptible P. aeruginosa strains were isolated from distinct clinical samples from hospitalized patients. These isolates were examined by PCR, MBL E-test, double-disk synergy test (DDST), and combined disk (CD) test. The minimal inhibitory concentration (MIC; μg/mL) was determined by agar dilution, and pulsed field gel electrophoresis (PFGE) was performed on all samples. Sequencing was performed to confirm and define the MBL variant and subtype. Using PCR and DNA sequence analysis, 93 strains were confirmed positive for MBLs, 91 strains for the blaSPM-1 gene, 1 strain for the blaIMP-1 gene, and 1 strain for the blaIMP-16 gene. PFGE displayed a clonal pattern. The sensitivities, specificities, positive and negative predictive values were evaluated for all tests. The DDST assay (CAZ-MPA) was the optimal method for screening MBL production in P. aeruginosa strains. However, the results of the CD assay (IMP/EDTA) showed close agreement with those of the DDST. In addition, the CD assay allowed a more objective interpretation and did not require the use of a toxic substance.
产金属β-内酰胺酶（MBL）的革兰氏阴性菌在全球范围内日益引起公共卫生关注。用于快速、特异性鉴定这些病原体的筛查试验至关重要，应纳入实验室的常规诊断项目中。本研究旨在确定耐碳青霉烯类铜绿假单胞菌分离株中MBL的频率，并评估不同试验筛查MBL产生的准确性。2001年1月至2008年12月，从住院患者的不同临床样本中总共分离出142株对亚胺培南不敏感的铜绿假单胞菌菌株。这些分离株通过聚合酶链反应（PCR）、MBL E试验、双纸片协同试验（DDST）和复合纸片（CD）试验进行检测。通过琼脂稀释法测定最低抑菌浓度（MIC；μg/mL），并对所有样本进行脉冲场凝胶电泳（PFGE）。进行测序以确认和定义MBL变体及亚型。通过PCR和DNA序列分析，93株菌株被确认为MBL阳性，91株为blaSPM - 1基因阳性，1株为blaIMP - 1基因阳性，1株为blaIMP - 16基因阳性。PFGE显示出克隆模式。对所有试验评估了敏感性、特异性、阳性和阴性预测值。DDST试验（CAZ - MPA）是筛查铜绿假单胞菌菌株中MBL产生的最佳方法。然而，CD试验（IMP/EDTA）的结果与DDST的结果显示出高度一致性。此外，CD试验允许更客观的解读，且无需使用有毒物质。
