Exploring the third-generation tetracycline resistance of multidrug-resistant livestock-associated methicillin-resistant Staphylococcus aureus ST9 across healthcare settings in China

Abstract

Background The overuse of antibiotics in livestock is contributing to the burden of antimicrobial resistance in humans, representing a One Health challenge. Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) has recently become a growing concern, and ST9 is the major LA-MRSA lineage in China and has emerged in clinical settings. Methods Antimicrobial susceptibility testing was used to evaluate the tetracycline resistance of ST9 MRSA collections, and gene cloning experiments were performed to explore the resistance mechanisms. Whole-genome sequencing and comparative genomics were used to analyse the genetic features of clinical ST9 isolates. A phylogenetic tree was constructed to investigate the relationship of human- and livestock-derived ST9 isolates. Results Clinical ST9 isolates were found to possess several types of resistance genes and resistance-related mutations and were multidrug-resistant. Notably, all clinical ST9 isolates were resistant to third-generation tetracyclines. Cloning experiments showed that both the acquisition of the tetracycline resistance gene tet(L)/tet(63) and a mutation in the rpsJ gene contributed to third-generation tetracycline resistance. Phylogenetic analysis showed that the ST9 isolates collected in healthcare systems were probably transmitted from livestock. The ST9 lineage underwent multiple interspecies recombination events and gained many resistance elements. Furthermore, the resistance to third-generation tetracyclines may have evolved under tetracycline pressure in livestock. Conclusions The evolution of ST9 MRSA in livestock and transmission of this clone between humans and livestock highlight the importance of establishing control strategies with the One Health approach to reduce the burden of antibiotic resistance.

Whole-Genome Investigation of Zoonotic Transmission of Livestock-Associated Methicillin-Resistant Staphylococcus aureus Clonal Complex 398 Isolated from Pigs and Humans in Thailand

“…In recent years, the carriage of multiple ccr gene complexes has been presented by a Chinese LA-MRSA ST9 from clinical and porcine isolates [26]. In addition, another study from China has reported the presence of coagulase-negative staphylococci (CoNS) carrying multiple SCCmec elements [27].…”

Genome-based surveillance reveals cross-transmission of MRSA ST59 between humans and retail livestock products in Hanzhong, China

“…Tetracyclines are a class of broad-spectrum antibiotics, including naturally occurring and semi-synthetic tetracyclines ( Roberts, 2003 ). Due to their side-effects, the use of tetracyclines is limited in human clinics, but they are still been used globally as important infection treatment measures and growth promoters among livestock animals which promoted the tetracycline resistant determinants transmission in livestock products ( Inglis et al, 2019 ; Chen et al, 2023 ). Since animals cannot fully absorb or metabolize tetracyclines, they excrete a significant fraction of such drugs or of their breakdown products into the environment via feces or urine which may also promote the transmission of resistant determinants ( Mackie et al, 2006 ).…”