Prevalence and characteristics of rmtB and qepA in Escherichia coli isolated from diseased animals in China

Yu-Ting Deng,Wei Tian,Tong Yang,Jian-Hua Liu,Zhen-Ling Zeng

doi:10.3389/fmicb.2013.00198

Yu-Ting Deng, Wei Tian + Show 3 more

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https://doi.org/10.3389/fmicb.2013.00198

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Abstract

16S rRNA methylase and QepA, a fluoroquinolone efflux pump, are new mechanisms of resistance against aminoglycosides and fluoroquinolone, respectively. One of 16S rRNA methylase genes, rmtB, was found to be associated with qepA, were both located on the same transposable element. In this study, we intended to determine the current prevalence and characteristics of the 16S rRNA methylase genes and qepA, and to study the association between rmtB and qepA. A total of 892 Escherichia coli isolates were collected from various diseased food-producing animals in China from 2004 to 2008 and screened by PCR for 16S rRNA methylase genes and qepA. About 12.6% (112/892) and 0.1% (1/892) of isolates that were highly resistant to amikacin were positive for rmtB and armA, respectively. The remaining five 16S rRNA methlyase genes were not detected. Thirty-six (4.0%) strains carried qepA. About 32.1% of rmtB-positive strains harbored qepA, which was not detected in rmtB-negative strains. Most strains were clonally unrelated, while identical PFGE profiles of rmtB-positive isolates were found in the same farm indicating clonal transmission. Conjugation experiments showed that rmtB was transferred to the recipients, and qepA also cotransferred with rmtB in some cases. The spread of E. coli of food animal origin harboring both rmtB and qepA suggests that surveillance for antimicrobial resistance of animal origin as well as the study of the mechanisms of resistance should be undertaken.

Highlights

In China, aminoglycosides and quinolone were commonly used for treating severe infections caused by Gram-negative bacteria in animal husbandry
DETECTION OF 16S rRNA METHYLASES GENES AND qepA In this study, 892 E. coli isolates originating from various diseased food-producing animals, including 360 pigs, 261 chickens, 179 ducks, 34 geese, 9 pigeons, 12 partridges, and 37 cows, were collected from six different provinces in China from 2004 to 2008
We found that 12.6% (112/892) of them carried rmtB gene, while the armA gene was detected in only one isolate

Summary

Introduction

In China, aminoglycosides and quinolone were commonly used for treating severe infections caused by Gram-negative bacteria in animal husbandry. A new type of mechanism, posttranscriptional methylation of the 16S rRNA, has been reported, and this results in high-level resistance to aminoglycoside antibiotics. Ten 16S rRNA methylase genes have been identified, including armA, rmtA, rmtB, rmtC, rmtD, rmtE, rmtF, rmtG, rmtH, and npmA, which are capable of conferring extraordinarily high levels of resistance to most clinically important aminoglycosides, including amikacin, gentamicin, kanamycin, and tobramycin (Galimand et al, 2003; Yokoyama et al, 2003; Doi and Arakawa, 2007; Wachino et al, 2007; Davis et al, 2010; Galimand et al, 2012; Bueno et al, 2013; O’Hara et al, 2013). The plasmid mediated efflux pump gene, qepA, which confers resistance to hydrophilic fluoroquinolones by efflux, has been reported recently to be frequently associated with the rmtB gene (Périchon et al, 2007; Yamane et al, 2007; Deng et al, 2011b; Yao et al, 2011)

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