Quesada-Gómez Carlos, Rodríguez-Cavallini Evelyn, Rodríguez César
Facultad de Microbiología, and Centro de Investigación en Enfermedades Tropicales (CIET), Universidad de Costa Rica, Ciudad Universitaria Rodrigo Facio, San Pedro Montes de Oca 2060, San José, Costa Rica.
Anaerobe. 2013 Jun;21:18-21. doi: 10.1016/j.anaerobe.2013.03.006. Epub 2013 Mar 22.
The frequency of finding of clindamycin-resistant anaerobic bacteria in clinical samples has doubled from 2008 to 2010 in Costa Rica. To determine whether this increase is due to dissemination of erm genes aided by tetQ elements, we analyzed 100 isolates of Bacteroides or Parabacteroides from a regional hospital, a national hospital, and the community. Antimicrobial susceptibilities were recorded with a broth micro-dilution method and erm genes were detected by PCR and Southern blotting. In addition, plasmid isolation and mating experiments were performed to clarify the location and mobility of the detected erm genes. Resistance to clindamycin was by far more frequent in the regional hospital (72%) than in the national hospital (29%) and the community (26%). Resistance to tetracycline was even more common, with the community (85%) outweighing the hospitals (71-72%). While MIC of clindamycin were higher in the hospitals than in the community (P < 0.05), the opposite was seen for tetracycline (P < 0.0001). Of the sought-after genes, only ermG (n = 2), ermA (n = 1), and ermF (n = 1) were detected in the hospitals and ermF in the community (n = 2). In opposition to the low frequency of finding of erm genes, 71% of the isolates were positive for tetQ. None of the detected genes were encoded on plasmids. Only three isolates from the hospitals transferred their erm genes laterally. By contrast, 13 hospital isolates and two community isolates transferred tetQ. Despite the widespread finding of tetracycline-resistant tetQ-positive bacteria, mobile erm genes were rare in our bacterial collection. We conclude that the detected erm genes are likely not included in typical conjugative transposons of Bacteroides and Parabacteroides.
在哥斯达黎加，临床样本中克林霉素耐药厌氧菌的检出率在2008年至2010年间翻了一番。为了确定这种增加是否是由于tetQ元件辅助erm基因的传播所致，我们分析了来自一家地区医院、一家国立医院和社区的100株拟杆菌属或副拟杆菌属菌株。采用肉汤微量稀释法记录抗菌药物敏感性，并通过PCR和Southern印迹法检测erm基因。此外，进行了质粒分离和接合实验，以阐明检测到的erm基因的位置和移动性。地区医院对克林霉素的耐药率（72%）远高于国立医院（29%）和社区（26%）。对四环素的耐药更为常见，社区（85%）高于医院（71 - 72%）。虽然医院中克林霉素的最低抑菌浓度高于社区（P < 0.05），但四环素的情况相反（P < 0.0001）。在所寻找的基因中，仅在医院中检测到ermG（n = 2）、ermA（n = 1）和ermF（n = 1），在社区中检测到ermF（n = 2）。与erm基因的低检出率相反，71%的分离株tetQ呈阳性。所有检测到的基因均未编码在质粒上。仅3株来自医院的分离株横向转移了它们的erm基因。相比之下，13株医院分离株和2株社区分离株转移了tetQ。尽管四环素耐药tetQ阳性细菌广泛存在，但在我们的细菌样本中可移动的erm基因很少见。我们得出结论，检测到的erm基因可能不包含在拟杆菌属和副拟杆菌属的典型接合转座子中。
