Department of Microbiology and Parasitology, Faculty of Medicine, Los Andes University, 5101 Mérida, Venezuela; Laboratory of Molecular Microbiology, Faculty of Pharmacy and Bioanalysis, Los Andes University, 5101 Mérida, Venezuela.
Laboratory of Molecular Microbiology, Faculty of Pharmacy and Bioanalysis, Los Andes University, 5101 Mérida, Venezuela.
J Glob Antimicrob Resist. 2018 Sep;14:45-50. doi: 10.1016/j.jgar.2018.02.004. Epub 2018 Feb 12.
Genetic mechanisms of resistance, clonal composition and the occurrence of pili were analysed in 48 multidrug-resistant (MDR) pneumococci isolated from healthy children in Mérida, Venezuela. Intermediate resistance to penicillin was related to variations in pbp2b and pbp2x. High-level resistance to penicillin as well as low susceptibility to cephalosporins and carbapenems were associated with alterations in pbp1a, pbp2b and pbp2x. Non-β-lactam resistance was associated with Tn3872, Tn5253, Tn6002 and Tn2010 transposons. Macrolide-resistant strains carried ermB or mefE, but not mefA. Tetracycline- and chloramphenicol-resistant pneumococci carried tetM and cat, respectively. MDR pneumococci were related to six clonal complexes (CCs), largely CC156 or CC15. Limited diversity in pbp2a,2b,2x-RFLP profiles within each clone was observed. Conversely, detection of non-β-lactam resistance and transposons revealed clear genetic diversity within clones. A group of non-typeable/cpsA-negative pneumococci related to the null capsule clade 1 (NCC1) carrying a Tn2009 element was found. Each NCC1-related strain showed a novel MLST allelic combination and a different pbp2a,2b,2x-RFLP profile. PI-1 (pilus type 1 rrgC gene) was present in most of the MDR pneumococci and its occurrence was commonly homogeneous within each clone. PI-1 was present in all CC242 and CC320 pneumococci, whereas it was absent in all CC37, CC81 and NCC1 isolates. CC156 and CC15 isolates showed variations in the occurrence of PI-1. Both PI-1 and the islet for pilus type 2 were present in CC320 isolates. We provide useful data to follow the evolution of clonal composition, mechanisms of antibiotic resistance and the occurrence of pili among pneumococci circulating in Mérida.
在委内瑞拉梅里达，对 48 株分离自健康儿童的多药耐药（MDR）肺炎链球菌进行了耐药基因、克隆组成和菌毛发生的分析。对青霉素的中介耐药与 pbp2b 和 pbp2x 的变异有关。对青霉素的高水平耐药以及对头孢菌素和碳青霉烯类的低敏感性与 pbp1a、pbp2b 和 pbp2x 的改变有关。非β-内酰胺耐药与 Tn3872、Tn5253、Tn6002 和 Tn2010 转座子有关。大环内酯类耐药株携带 ermB 或 mefE，但不携带 mefA。四环素和氯霉素耐药肺炎链球菌分别携带 tetM 和 cat。MDR 肺炎链球菌与六个克隆复合体（CC）有关，主要是 CC156 或 CC15。每个克隆内 pbp2a、2b、2x-RFLP 谱的 pbp2a、2b、2x 型多样性有限。相反，非β-内酰胺耐药和转座子的检测显示出克隆内的明显遗传多样性。发现了一组与无荚膜/ cpsA 阴性肺炎链球菌相关的、携带 Tn2009 元件的空壳类 1（NCC1）的非定型/ cpa 阴性肺炎链球菌。每个与 NCC1 相关的菌株都表现出一种新的 MLST 等位基因组合和不同的 pbp2a、2b、2x-RFLP 谱。PI-1（菌毛 1 rrgC 基因）存在于大多数 MDR 肺炎链球菌中，并且在每个克隆中通常是同质的。PI-1 存在于所有 CC242 和 CC320 肺炎链球菌中，而在所有 CC37、CC81 和 NCC1 分离株中均不存在。CC156 和 CC15 分离株在 PI-1 发生的变异。PI-1 和菌毛 2 岛都存在于 CC320 分离株中。我们提供了有用的数据，以跟踪梅里达流行的肺炎链球菌中克隆组成、抗生素耐药机制和菌毛发生的演变。
