Migratory wild birds carrying multidrug-resistant Escherichia coli as potential transmitters of antimicrobial resistance in China.

Yang Sun,Yue Yuan,Bo-Wen Jiang,Xue Ji,Bing Liang,Abdelazeem Mohamed Algammal,Tie-Cheng Wang,Xue-Jun Guo,Jun Liu,Ling-Wei Zhu,Yuan-Guo Li

doi:10.1371/journal.pone.0261444

Abstract

Migratory birds play an important role in the spread of multidrug-resistant (MDR) bacteria. To investigate the prevalence of MDR Escherichia coli in migratory birds in China and potential relationships with the environment, a total of 1387 samples (fecal samples, cloacal swabs, or throat swabs) were collected from migratory birds from three different river basins in China. The collected samples were processed and subjected to bacteriological examinations. Antimicrobial susceptibility testing of the recovered isolates was performed using the E-test for the detection of minimum inhibitory concentrations (MICs). Some antibiotic resistance genes were detected and the PCR products were confirmed by sequencing. In total, 478 (34.7%) E. coli isolates were recovered. The results showed that the drug-resistant E. coli isolates were highly resistant to β-lactams (43.7%) and tetracycline (22.6%), and 73 (15.3%) were MDR, including eight that were extended spectrum β-lactamase-positive. The retrieved strains harbored the blaCTX-M, blaTEM-1, tet(A), tet(B), tet(M), sul1, sul2, sul3, cmlA, floR, and intI1 genes with a prevalence of 5.9%, 36.4%, 80.5%, 11.9%, 6.8%, 6.8%, 47.5%, 12.7%, 50.8%, 37.3%, and 61.0%, respectively. The drug resistance rate of the isolates from southern China was higher than those from northern China. The E. coli samples collected for migratory birds in the Pearl River Basin had the highest proportion (46.7%) MDR isolates. Furthermore, MDR bacteria carried by migratory birds were closely related to the antibiotic content in the basin, which confirms that MDR bacteria carried by migratory birds are likely acquired from the environment. This study also confirmed that migratory birds are potential transmitters of MDR bacteria, demonstrating the need to reduce the use and emission of antibiotics and further in-depth studies on the mechanisms underlying drug resistance of bacteria.

Highlights

Antimicrobial resistance (AMR) is among the most important threats to public health
Several recent investigations reported the emergence of MDR bacterial pathogens from different origins, including humans, birds, cattle, and fish, which increase the need for routine antimicrobial susceptibility testing to choose an appropriate antibiotic as well as the screening of the emerging MDR strains
Migratory wild birds carrying MDR E. coli might be act as potential transmitters of antimicrobial resistance in China

Summary

Introduction

Antimicrobial resistance (AMR) is among the most important threats to public health. The resulting spread of multidrug-resistant (MDR) bacteria and antibiotic resistance genes (ARGs) poses a significant threat to the health of humans and animals worldwide [1,2]. Several recent investigations reported the emergence of MDR bacterial pathogens from different origins, including humans, birds, cattle, and fish, which increase the need for routine antimicrobial susceptibility testing to choose an appropriate antibiotic as well as the screening of the emerging MDR strains. Β-lactam drugs account for about 60% of all prescribed antibacterial agents, probably due to safety and adequacy Overuse of these agents had led to the rapid emergence of MDR pathogens [10]. The frequent occurrence of MDR bacteria indicates the excessive and arbitrary use of antibiotics, which poses a great threat to public health, and reflects the necessity for the development of new potent and safe antibiotics [11]

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Discussion

Conclusion