Jure María A, Presti Constanza, Cudmani Norma M, Grellet Lidia M, López Carolina, Musa Eduardo H, Aulet Olga C, Nieto Carlos, Saavedra Lucila, de Castillo Marta Cecilia
Instituto de Microbiología Dr. Luis C. Verna, Cátedra de Bacteriología, Facultad de Bioquímica, Química, Farmacia y Biotecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán.
Rev Argent Microbiol. 2011 Jan-Mar;43(1):24-7. doi: 10.1590/S0325-75412011000100005.
In the last years, Enterobacteriaceae such as Klebsiella pneumoniae, Proteus mirabilis and Escherichia coli, have acquired resistance to third-generation cephalosporins (C3G) because of the presence of plasmid-mediated AmpC ß-lactamases. The aim of this work was to detect plasmid AmpC enzymes and to investigate the predominant types in our region. Between March and July 2009, 733 consecutive isolates of Enterobacteriaceae derived from hospitals and outpatient centers were studied. Susceptibility testing was performed by disk diffusion; one P. mirabilis and three E. coli strains showed resistance to cephamycins (cefoxitin) and C3G. An E-test to determine MIC and a synergy test by aminophenylboronic disks were performed. Enzymatic activity against cefoxitin was confirmed by a microbiological assay. A polymerase chain reaction (PCR) for the detection of plasmid-mediated ampC genes of different groups was performed and a 462-bp amplicon was obtained when using primers directed against the CIT group; the obtained sequences were compared to blaCMY-2 sequences, showing 100% identity. The emergence of CMY-2-type plasmid-mediated AmpC ß-lactamases indicated the importance of implementing systematic monitoring of these resistances to avoid potential clinical and epidemiological consequences.
在过去几年中，肺炎克雷伯菌、奇异变形杆菌和大肠杆菌等肠杆菌科细菌由于存在质粒介导的AmpCβ-内酰胺酶，已对第三代头孢菌素（C3G）产生耐药性。这项工作的目的是检测质粒AmpC酶，并调查我们地区的主要类型。2009年3月至7月，对来自医院和门诊中心的733株连续分离的肠杆菌科细菌进行了研究。采用纸片扩散法进行药敏试验；1株奇异变形杆菌和3株大肠杆菌对头孢霉素（头孢西丁）和C3G耐药。进行E试验以确定最低抑菌浓度（MIC），并通过氨基苯基硼酸纸片进行协同试验。通过微生物学测定证实了对头孢西丁的酶活性。进行聚合酶链反应（PCR）以检测不同组的质粒介导的ampC基因，当使用针对CIT组的引物时获得了一个462 bp的扩增子；将获得的序列与blaCMY-2序列进行比较，显示100%同一性。CMY-2型质粒介导的AmpCβ-内酰胺酶的出现表明实施这些耐药性的系统监测以避免潜在临床和流行病学后果的重要性。
