López-García Alma, Rocha-Gracia Rosa Del Carmen, Bello-López Elena, Juárez-Zelocualtecalt Claudia, Sáenz Yolanda, Castañeda-Lucio Miguel, López-Pliego Liliana, González-Vázquez María Cristina, Torres Carmen, Ayala-Nuñez Teolincacihuatl, Jiménez-Flores Guadalupe, Arenas-Hernández Margarita María de la Paz, Lozano-Zarain Patricia
Benemérita Universidad Autónoma de Puebla, Instituto de Ciencias, Posgrado en Microbiología, Centro de Investigaciones en Ciencias Microbiológicas, Complejo de Ciencias, Ciudad Universitaria. Col San Manuel CP, Puebla, Mexico,
Area de Microbiología Molecular, Centro de Investigación Biomédica de La Rioja (CIBIR), Logroño, Spain.
Infect Drug Resist. 2018 Sep 20;11:1523-1536. doi: 10.2147/IDR.S173455. eCollection 2018.
infections in hospitals constitute an important problem due to the increasing multidrug resistance (MDR) and carbapenems resistance. The knowledge of resistance mechanisms in strains is an important issue for an adequate antimicrobial treatment. Therefore, the objective was to investigate other antimicrobial resistance mechanisms in MDR strains carrying , make a partial plasmids characterization, and determine if modifications in gene affect the expression of the OprD protein.
Susceptibility testing was performed by Kirby Baüer and by Minimum Inhibitory Concentration (presence/absence of efflux pump inhibitor); molecular typing by Pulsed-field gel electrophoresis (PFGE), resistance genotyping and integrons by PCR and sequencing; OprD expression by Western blot; plasmid characterization by MOB Typing Technique, molecular size by PFGE-S1; and location by Southern blot.
Among the 59 studied isolates, 41 multidrug resistance and carbapenems resistance isolates were detected and classified in 38 different PFGE patterns. Thirteen strains carried 16 and four carried both genes. This study centered on the 17 strains har-boring . New variants of β-lactamases were identified ( , , ) inside of new arrangements of class 1 integrons. The presence of gene was detected in two plasmids in the same strain. The participation of the OprD protein and efflux pumps in the resistance to carbapenems and quinolones is shown. No expression of the porin OprD due to stop codon or IS in the gene was found.
This study shows the participation of different resistance mechanisms, which are reflected in the levels of MIC to carbapenems. This is the first report of the presence of three new variants of β-lactamases inside of new arrangements of class 1 integrons, as well as the presence of two plasmids carrying in the same strain isolated in a Mexican hospital.
由于多重耐药（MDR）和碳青霉烯类耐药性的增加，医院感染构成了一个重要问题。了解菌株中的耐药机制是进行适当抗菌治疗的重要问题。因此，本研究的目的是调查携带 blaVIM-2 的 MDR 菌株中的其他抗菌耐药机制，对部分质粒进行表征，并确定 blaOprD 基因的修饰是否会影响 OprD 蛋白的表达。
采用 Kirby-Bauer 法和最低抑菌浓度法（有无外排泵抑制剂）进行药敏试验；通过脉冲场凝胶电泳（PFGE）进行分子分型，通过 PCR 和测序进行耐药基因分型和整合子分析；通过 Western blot 检测 OprD 表达；采用 MOB 分型技术进行质粒表征，通过 PFGE-S1 测定分子大小；通过 Southern blot 确定 blaVIM-2 的位置。
在 59 株研究的鲍曼不动杆菌分离株中，检测到 41 株多重耐药和碳青霉烯类耐药分离株，并分为 38 种不同的 PFGE 模式。13 株携带 blaVIM-16，4 株同时携带这两个基因。本研究聚焦于携带 blaVIM-2 的 17 株菌株。在 1 类整合子的新排列中鉴定出新型β-内酰胺酶变体（blaVIM-17、blaVIM-18、blaVIM-19）。在同一菌株的两个质粒中检测到 blaVIM-2 基因的存在。显示了 OprD 蛋白和外排泵在对碳青霉烯类和喹诺酮类耐药中的作用。未发现由于 blaOprD 基因中的终止密码子或插入序列导致孔蛋白 OprD 不表达。
本研究显示了不同耐药机制的参与，这反映在对碳青霉烯类的 MIC 水平上。这是首次报道在 1 类整合子的新排列中存在三种新型β-内酰胺酶变体，以及在墨西哥一家医院分离的同一鲍曼不动杆菌菌株中存在携带 blaVIM-2 的两个质粒。
