Yu-Zhang He1,2,3,4, Xu Kuang1,2,3,4, Teng-Fei Long1,2,3,4, Gong Li1,2,3,4, Hao Ren1,2,3,4, Bing He1,2,3,4, Jin-Ru Yan1,2,3,4, Xiao-Ping Liao1,2,3,4, Ya-Hong Liu1,2,3,4, Liang Chen5,6, Jian Sun1,2,3,4. 1. Center for Emerging and Zoonotic Diseases, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong 510642, China. 2. Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China. 3. National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China. 4. Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China. 5. Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ 07110, USA. 6. Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ 07110, USA.
Abstract
OBJECTIVES: In this study, we developed an IS26-based CRISPR/Cas9 system as a proof-of-concept study to explore the potential of a re-engineered bacterial translocatable unit (TU) for curing and immunizing against the replication genes and antimicrobial resistance genes. METHODS: A series of pIS26-CRISPR/Cas9 suicide plasmids were constructed, and specific guide RNAs were designed to target the replication gene of IncX4, IncI2 and IncHI2 plasmids, and the antibiotic resistance genes mcr-1, blaKPC-2 and blaNDM-5. Through conjugation and induction, the transposition efficiency and plasmid-curing efficiency in each recipient were tested. In addition, we examined the efficiency of the IS26-CRISPR/Cas9 system of cell immunity against the acquisition of the exogenous resistant plasmids by introducing this system into antimicrobial-susceptible hosts. RESULTS: This study aimed to eliminate the replication genes and antimicrobial resistance genes using pIS26-CRISPR/Cas9. Three plasmids with different replicon types, including IncX4, IncI2 and IncHI2 in three isolates, two pUC19-derived plasmids, pUC19-mcr-1 and pUC19-IS26mcr-1, in two lab strains, and two plasmids bearing blaKPC-2 and blaNDM-5 in two isolates were all successfully eliminated. Moreover, the IS26-based CRISPR/Cas9 system that remained in the plasmid-cured strains could efficiently serve as an immune system against the acquisition of the exogenous resistant plasmids. CONCLUSIONS: The IS26-based CRISPR/Cas9 system can be used to efficiently sensitize clinical Escherichia coli isolates to antibiotics in vitro. The single-guide RNAs targeted resistance genes or replication genes of specific incompatible plasmids that harboured resistance genes, providing a novel means to naturally select bacteria that cannot uptake and disseminate such genes.
OBJECTIVES: In this study, we developed an IS26-based CRISPR/Cas9 system as a proof-of-concept study to explore the potential of a re-engineered bacterial translocatable unit (TU) for curing and immunizing against the replication genes and antimicrobial resistance genes. METHODS: A series of pIS26-CRISPR/Cas9 suicide plasmids were constructed, and specific guide RNAs were designed to target the replication gene of IncX4, IncI2 and IncHI2 plasmids, and the antibiotic resistance genes mcr-1, blaKPC-2 and blaNDM-5. Through conjugation and induction, the transposition efficiency and plasmid-curing efficiency in each recipient were tested. In addition, we examined the efficiency of the IS26-CRISPR/Cas9 system of cell immunity against the acquisition of the exogenous resistant plasmids by introducing this system into antimicrobial-susceptible hosts. RESULTS: This study aimed to eliminate the replication genes and antimicrobial resistance genes using pIS26-CRISPR/Cas9. Three plasmids with different replicon types, including IncX4, IncI2 and IncHI2 in three isolates, two pUC19-derived plasmids, pUC19-mcr-1 and pUC19-IS26mcr-1, in two lab strains, and two plasmids bearing blaKPC-2 and blaNDM-5 in two isolates were all successfully eliminated. Moreover, the IS26-based CRISPR/Cas9 system that remained in the plasmid-cured strains could efficiently serve as an immune system against the acquisition of the exogenous resistant plasmids. CONCLUSIONS: The IS26-based CRISPR/Cas9 system can be used to efficiently sensitize clinical Escherichia coli isolates to antibiotics in vitro. The single-guide RNAs targeted resistance genes or replication genes of specific incompatible plasmids that harboured resistance genes, providing a novel means to naturally select bacteria that cannot uptake and disseminate such genes.