Martínez-Álvarez Sandra, Châtre Pierre, François Pauline, Abdullahi Idris Nasir, Simón Carmen, Zarazaga Myriam, Madec Jean-Yves, Haenni Marisa, Torres Carmen
Area of Biochemistry and Molecular Biology, OneHealth-UR Research Group, University of La Rioja, Logroño, Spain.
ANSES - Université de Lyon, Unité Antibiorésistance et Virulence Bactériennes, Lyon, France.
Ecotoxicol Environ Saf. 2024 Mar 15;273:116145. doi: 10.1016/j.ecoenv.2024.116145. Epub 2024 Mar 9.
The presence of methicillin-resistant or -susceptible S. aureus in pig nostrils has been known for a long time, but the occurrence of extended-spectrum beta-lactamase (ESBL)-producing E. coli has hardly been investigated. Here, we collected 25 E. coli recovered from nasal samples of 40 pigs/10 farmers of four farms. Nine ESBL-producing isolates belonging to ST48, ST117, ST847, ST5440, ST14914 and ST10 were retrieved from seven pigs. All bla genes (blablablabla and bla) were horizontally transferable by conjugation through plasmids belonging to IncI1 (n=3), IncX1 (n=3) and IncHI2 (n=1) types. IncI1-plasmids displayed different genetic environments: i) IS26-bla-deoR-IS26, ii) wbuC-bla-ISKpn26 (IS5), and iii) IS930-bla-IS26. The IncHI2-plasmid contained the genetic environment IS903-bla-fipA with multiple resistance genes associated either to: a) Tn21-like transposon harbouring genes conferring aminoglycosides/beta-lactams/chloramphenicol/macrolides resistance located on two atypical class 1 integrons with an embedded ΔTn5393; or b) Tn1721-derived transposon displaying an atypical class 1 integron harbouring aadA2-arr3-cmlA5-bla-aadA24-dfrA14, preceding the genetic platform IS26-bla-tet(A)-lysR-floR-virD2-ISVsa3-IS3075-IS26-qnrS1, as well as the tellurite resistance module. Other plasmids harbouring clinically relevant genes were detected, such as a ColE-type plasmid carrying the mcr-4.5 gene. Chromosomally encoded genes (fosA7) or integrons (intI1-dfrA1-aadA1-qacE-sul1/intI1-IS15-dfrA1-aadA2) were also identified. Finally, an IncY plasmid harbouring a class 2 integron (intI2-dfrA1-sat2-aadA1-qacL-IS406-sul3) was detected but not associated with a bla gene. Our results evidence that pig nostrils might favour the spread of ESBL-E. coli and mcr-mediated colistin-resistance. Therefore, enhanced monitoring should be considered, especially in a sector where close contact between animals in intensive farming increases the risk of spreading antimicrobial resistance.
长期以来，人们已经知道猪的鼻孔中存在耐甲氧西林或对甲氧西林敏感的金黄色葡萄球菌，但对产超广谱β-内酰胺酶（ESBL）的大肠杆菌的发生情况几乎没有进行过研究。在这里，我们从四个农场的40头猪/10位养殖户的鼻腔样本中收集了25株大肠杆菌。从7头猪中分离出9株产ESBL的菌株，它们分别属于ST48、ST117、ST847、ST5440、ST14914和ST10。所有bla基因（bla bla bla bla和bla）均可通过属于IncI1（n = 3）、IncX1（n = 3）和IncHI2（n = 1）类型的质粒进行接合水平转移。IncI1质粒表现出不同的遗传环境：i）IS26-bla-deoR-IS26，ii）wbuC-bla-ISKpn26（IS5），以及iii）IS930-bla-IS26。IncHI2质粒包含遗传环境IS903-bla-fipA，带有多个抗性基因，这些基因与以下两种情况相关：a）Tn21样转座子，其携带赋予氨基糖苷类/β-内酰胺类/氯霉素/大环内酯类抗性的基因，位于两个带有嵌入式ΔTn5393的非典型1类整合子上；或b）源自Tn1721的转座子，显示出一个非典型1类整合子，携带aadA2-arr3-cmlA5-bla-aadA24-dfrA14，位于遗传平台IS26-bla-tet(A)-lysR-floR-virD2-ISVsa3-IS3075-IS26-qnrS1之前，以及亚碲酸盐抗性模块。还检测到了其他携带临床相关基因的质粒，例如携带mcr-4.5基因的ColE型质粒。也鉴定出了染色体编码基因（fosA7）或整合子（intI1-dfrA1-aadA1-qacE-sul1/intI1-IS15-dfrA1-aadA2）。最后，检测到一个携带2类整合子（intI2-dfrA1-sat2-aadA1-qacL-IS406-sul3）的IncY质粒，但它与bla基因无关。我们的结果表明，猪的鼻孔可能有利于产ESBL大肠杆菌和mcr介导的黏菌素抗性的传播。因此，应考虑加强监测，尤其是在集约化养殖中动物之间密切接触会增加抗菌药物耐药性传播风险的行业。
