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BMC Microbiol. 2018 Dec 27;18(1):225. doi: 10.1186/s12866-018-1368-4.

Quinolone resistance phenotype and genetic characterization of Salmonella enterica serovar Pullorum isolates in China, during 2011 to 2016.

Guo X1,2, Wang H1,3, Cheng Y1,4, Zhang W1,4, Luo Q1,3, Wen G1,4, Wang G2, Shao H5,6, Zhang T7,8.

Author information

1
Key Laboratory of Prevention and Control Agents for Animal Bacteriosis, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan, China.
2
College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.
3
Hubei Engineering Technology Center of Veterinary Diagnostic products, Wuhan, 430070, China.
4
Hubei Key Laboratory of Animal Embryo and Molecular Breeding, Institute of Animal and Veterinary Science, Hubei Academy of Agricultural Sciences, Wuhan, China.
5
Key Laboratory of Prevention and Control Agents for Animal Bacteriosis, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan, China. shhb1961@163.com.
6
Hubei Engineering Technology Center of Veterinary Diagnostic products, Wuhan, 430070, China. shhb1961@163.com.
7
Key Laboratory of Prevention and Control Agents for Animal Bacteriosis, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan, China. tfzhang23@163.com.
8
Hubei Key Laboratory of Animal Embryo and Molecular Breeding, Institute of Animal and Veterinary Science, Hubei Academy of Agricultural Sciences, Wuhan, China. tfzhang23@163.com.

Abstract

BACKGROUND:

Pullorum disease, caused by Salmonella enterica serovar Pullorum (S. Pullorum), is one of the most important bacterial infections in the poultry industry in developing countries, including China. To examine the prevalence and characteristics of S. Pullorum, the Multilocus Sequence Typing (MLST) genotypes, fluoroquinolones resistance, and biofilm-forming abilities of S. Pullorum isolates were investigated, collected from 2011 to 2016 in China.

RESULTS:

Thirty S. Pullorum isolates collected from 2011 to 2016 were analyzed. Quinolones susceptibility testing showed that 90% of the isolates were resistant to the first generation of quinolines nalidixic acid, but the resistance rates to different fluoroquinolones agents were lower than 13.3%; for some there was even no resistance. Multilocus sequence typing (MLST) showed that ST-92 was the dominating genotype, accounting for 90.0% of all S. pullorum strains. The remaining three isolates were of the new reported sequence type ST-2151. Interestingly, the Asp87Gly substitution in quinolone resistance-determining regions (QRDR) of GyrA was only observed in the three strains of ST-2151, suggesting a potential correlation between Asp87Gly substitution and sequence type (pā€‰<ā€‰0.05). However, Asp87Gly substitution could not confer the resistant to ofloxacin and ciprofloxacin of these isolates. The plasmid-mediated quinolone resistance (PMQR) gene was not found in any of the tested isolates. Furthermore, an assay measuring biofilm-forming abilities showed that 46.7% of the isolates were non-biofilm producers, while 53.3% could form very weak biofilms, which might explain the relatively lower resistance to fluoroquinolones.

CONCLUSIONS:

We reported a high resistance rate to the first generation of quinolines nalidixic acid and relatively low resistance rates to fluoroquinolones in S. Pullorum isolates. In addition, weak biofilm-forming abilities were found, which might be an important reason of the low fluoroquinolones resistance rates of S. Pullorum isolates. ST-92 was the dominating genotype demonstrated by MLST, and the new sequence type ST-2151 showed a potential correlation with Asp87Gly substitution in QRDR of GyrA. We believe the characterization of these S. Pullorum isolates will be helpful to develop prevention and control strategies.

KEYWORDS:

Biofilm; Chicken; MLST; Quinolone resistance; Salmonella enterica serovar Pullorum

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