Epidemic and molecular characterization of fluoroquinolone-resistant Shigella dysenteriae 1 isolates from calves with diarrhea
Background: The widespread distribution of antimicrobial-resistant Shigella has become a recurrent challenge in many parts of the developing world. Previous studies indicate that the host of Shigella has expanded from humans to animals. This study aimed to investigate the prevalence of fluoroquinolone resistance and associated molecular characterization of S. dysenteriae 1 isolated from calves.
Results: All 38 unduplicated S. dysenteriae 1 isolates were collected from calves in Gansu Province from October 2014 to December 2016. According to MLST and PFGE analysis, these isolates were separated into 4 and 28 genotypes, respectively. The most common STs identified were ST228 (34.21%, 13/38) and ST229 (39.47%, 15/38), which were first found in the present study. All isolates harbored virulence genes, and the incidence of the seven virulence genes were ipaH (100%), ipaBCD (92.11%), stx (73.68%), ial (57.89%), sen (28.95%), set1A and set1B. According to the results of antimicrobial susceptibilities, 76.32% (29/38) were resistant to fluoroquinolone and showed multidrug resistance. In a study on the polymorphism of quinolone resistance–determining region (QRDR) of gyrA/B and parC/E genes, we identified two mutations in gyrA (Ser83→Leu and Asp87→Asn) and parC (Ser80→Ile and Ser83→Leu), respectively. Among them, 55.17% (16/29) of resistant strains had the gyrA point mutations (Ser83→Leu) and parC point mutation (Ser83→Leu). Moreover, 41.38% (12/29) of isolates had all five point mutations of gyrA and parC. In addition, the prevalence of the plasmid-mediated quinolone resistance (PMQR) determinant genes was also investigated. All 29 fluoroquinolone-resistant isolates were positive for the aac(6’)-Ib-cr gene but negative for qepA, except SD001. In addition, only 6 (20.69%, 6/29) isolates harbored the qnr gene, including two with qnrB (6.90%, 2/29) and four with qnrS (13.79%, 4/29).
Conclusion: Given the increased common emergence of multidrug resistant isolates, uninterrupted surveillance will be necessary to understand the actual epidemic burden and control this infection.
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Epidemic and molecular characterization of fluoroquinolone-resistant Shigella dysenteriae 1 isolates from calves with diarrhea
On 13 Nov, 2020
Received 13 Nov, 2020
On 12 Nov, 2020
Invitations sent on 12 Nov, 2020
On 12 Nov, 2020
On 12 Nov, 2020
Posted 10 Sep, 2020
On 29 Oct, 2020
Received 25 Oct, 2020
Received 20 Oct, 2020
Received 07 Oct, 2020
On 05 Oct, 2020
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Invitations sent on 02 Oct, 2020
On 02 Oct, 2020
On 07 Sep, 2020
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Received 11 Aug, 2020
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On 17 Jul, 2020
On 17 Jul, 2020
On 02 Jul, 2020
On 01 Jul, 2020
On 01 Jul, 2020
On 01 Jul, 2020
Background: The widespread distribution of antimicrobial-resistant Shigella has become a recurrent challenge in many parts of the developing world. Previous studies indicate that the host of Shigella has expanded from humans to animals. This study aimed to investigate the prevalence of fluoroquinolone resistance and associated molecular characterization of S. dysenteriae 1 isolated from calves.
Results: All 38 unduplicated S. dysenteriae 1 isolates were collected from calves in Gansu Province from October 2014 to December 2016. According to MLST and PFGE analysis, these isolates were separated into 4 and 28 genotypes, respectively. The most common STs identified were ST228 (34.21%, 13/38) and ST229 (39.47%, 15/38), which were first found in the present study. All isolates harbored virulence genes, and the incidence of the seven virulence genes were ipaH (100%), ipaBCD (92.11%), stx (73.68%), ial (57.89%), sen (28.95%), set1A and set1B. According to the results of antimicrobial susceptibilities, 76.32% (29/38) were resistant to fluoroquinolone and showed multidrug resistance. In a study on the polymorphism of quinolone resistance–determining region (QRDR) of gyrA/B and parC/E genes, we identified two mutations in gyrA (Ser83→Leu and Asp87→Asn) and parC (Ser80→Ile and Ser83→Leu), respectively. Among them, 55.17% (16/29) of resistant strains had the gyrA point mutations (Ser83→Leu) and parC point mutation (Ser83→Leu). Moreover, 41.38% (12/29) of isolates had all five point mutations of gyrA and parC. In addition, the prevalence of the plasmid-mediated quinolone resistance (PMQR) determinant genes was also investigated. All 29 fluoroquinolone-resistant isolates were positive for the aac(6’)-Ib-cr gene but negative for qepA, except SD001. In addition, only 6 (20.69%, 6/29) isolates harbored the qnr gene, including two with qnrB (6.90%, 2/29) and four with qnrS (13.79%, 4/29).
Conclusion: Given the increased common emergence of multidrug resistant isolates, uninterrupted surveillance will be necessary to understand the actual epidemic burden and control this infection.
Figure 1
Figure 2
Figure 3