摘要
      产生β-内酰胺酶的细菌的传播备受关注，环境已被发现是污染的主要来源。在此，建议使用表型和分子方法来确定整个勒马河流域抗微生物革兰氏阴性菌的频率。用显色培养基分离耐药细菌，并用抗菌药敏试验来表征其耐药性。通过PCR检测β-内酰胺类、氨基糖苷类和喹诺酮类的ARGs。物种通过Sanger 16S rRNA基因测序进行鉴定，耐多药菌株的代表性基因组通过NGS测序。在20个采样点中观察到分离物数量的高度变化，同时观察到抗性细菌的多样性较低。在12个已鉴定的细菌群中，弗氏梭菌、大肠杆菌和粘质链霉菌更为突出。证明了对β-内酰胺类、喹诺酮类和氨基糖苷类的高频率耐药性，其中blaCTX、qnrB、qnrS y和aac（6′）lb-cr基因最为普遍。弗氏梭菌显示出最高频率的耐多药菌株。全基因组测序显示，粘质链霉菌和肺炎克雷伯菌显示出大量的共同毒力和抗微生物耐药性基因，而大肠杆菌显示出最多的独特基因。携带各种ARG的MDR菌株对勒马河的污染应提高环境当局的认识，以评估这条重要河流的最佳卫生和卫生条件的风险和法规，这条河流支持墨西哥不同社区的经济活动。
Abstract
The spread of beta-lactamase-producing bacteria is of great concern and the environment has been found to be a main source of contamination. Herein, it was proposed to determine the frequency of antimicrobial-resistant-Gram-negative bacteria throughout the Lerma River basin using phenotypic and molecular methods. Resistant bacteria were isolated with chromogenic media and antimicrobial susceptibility tests were used to characterize their resistance. ARGs for beta-lactams, aminoglycosides, and quinolones were detected by PCR. Species were identified by Sanger sequencing the 16S rRNA gene and the representative genomes of MDR strains were sequenced by NGS. A high variation in the number of isolates was observed in the 20 sampled sites, while observing a low diversity among the resistant bacteria. Of the 12 identified bacterial groups, C. freundii, E. coli, and S. marcescens were more predominant. A high frequency of resistance to beta-lactams, quinolones, and aminoglycosides was evidenced, where the blaCTX, qnrB, qnrS y, and aac(6′)lb-cr genes were the most prevalent. C. freundii showed the highest frequency of MDR strains. Whole genome sequencing revealed that S. marcescens and K. pneumoniae showed a high number of shared virulence and antimicrobial resistance genes, while E. coli showed the highest number of unique genes. The contamination of the Lerma River with MDR strains carrying various ARGs should raise awareness among environmental authorities to assess the risks and regulations regarding the optimal hygienic and sanitary conditions for this important river that supports economic activities in the different communities in Mexico.

https://www.mdpi.com/1660-4601/19/21/13988