• YAKHAK HOEJI
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• v.60 no.1
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• pp.1-7
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• 2016

The aim of this study was to investigate the prevalence of quinolone resistant E. coli from retail meat and to characterize the resistant determinants. Determination of minimum inhibitory concentration, the sequence analysis of gyrA, gyrB, parC, and parE quinolone resistance determining regions (QRDR), the presences of plasmid mediated quinolone resistance (PMQR) and the expression of efflux pump genes were investigated. Of the total 277 retail meat samples, 67 coli form bacteria were isolated. 15 of 67 isolates showed nalidixic acid resistance and 7 of 15 nalidixic acid resistant isolates were also resistant to ciprofloxacin, moxifloxacin and levofloxacin. 11 of 15 nalidixic acid resistant strains were isolated from chicken, 2 of 15 were isolated from beef and 2 of 15 were isolated from pork samples. 11 of 15 nalidixic acid resistant strains have single mutation at codon 87 (D87N or D87G) in gyrA, 2 of 11 gyrA mutants have double mutations at codon 86 and 87 (L86A and L87I) in parC with mutations at codon 434+445+465 or 429 in gyrB. 2 of 15 resistant isolates harbored qnrS, a PMQR determinant. Over expression of the acrB gene, efflux pump gene (3.93~16.53 fold), was observed in 10 of 15 resistant isolates.

• Korean Journal of Environmental Agriculture
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• v.41 no.4
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• pp.335-343
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• 2022

BACKGROUND: Antibiotics used in animal husbandry for disease prevention and treatment have resulted in the rapid progression of antibiotic resistant bacteria which can be introduced into the environment through livestock feces/manure, disseminating antibiotic resistant genes (ARGs). In this study, fecal samples were collected from the livestock farms located in Jeju Island to investigate the relationship between microbial communities and ARGs. METHODS AND RESULTS: Illumina MiSeq sequencing was applied to characterize microbial communities within each fecal sample. Using quantitative PCR (qPCR), ten ARGs encoding tetracycline resistance (tetB, tetM), sulfonamide resistance (sul1, sul2), fluoroquinolone resistance (qnrD, qnrS), fluoroquinolone and aminoglycoside resistance (aac(6')-Ib), beta-lactam resistance (bla_TEM, bla_CTX-M), macrolide resistance (ermC), a class 1 integronsintegrase gene (intI1), and a class 2 integrons-integrase gene (intI2) were quantified. The results showed that Firmicutes and Bacteroidetes were dominant in human, cow, horse, and pig groups, while Firmicutes and Actinobacteria were dominant in chicken group. Among ARGs, tetM was detected with the highest number of copies, followed by sul1 and sul2. Most of the genera belonging to Firmicutes showed positive correlations with ARGs and integron genes. There were 97, 34, 31, 25, and 22 genera in chicken, cow, pig, human, and horse respectively which showed positive correlations with ARGs and integron genes. In network analysis, we identified diversity of microbial communities which correlated with ARGs and integron genes. CONCLUSION(S): In this study, antibiotic resistance patterns in human and livestock fecal samples were identified. The abundance of ARGs and integron genes detected in the samples were associated with the amount of antibiotics commonly used for human and livestocks. We found diverse microbial communities associated with antibiotics resistance genes in different hosts, suggesting that antibiotics resistance can disseminate across environments through various routes. Identifying the routes of ARG dissemination in the environment would be the first step to overcome the challenge of antibiotic resistance in the future.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.2
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• pp.118-123
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• 2016

Antimicrobial agents have been used in poultry for treatment of bacterial infections or additives over the past half century. However, increasing antimicrobial resistance has led to selective pressure for therapeutic use in humans and made treatment of bacterial infection more difficult. In this study, we examined the prevalence of plasmid mediated antimicrobial resistant determinants for resistance to ${\beta}-lactam$, quinolone, and aminoglycoside in Enterobacteriaceae isolates obtained from chickens in Gyeongsang provinces, and correlation between the resistant genes and antimicrobial resistance rate was also assessed. A total of 43 Enterobacteriaceae isolates were recovered from 40 chickens at Gyeongsang provinces in Korea. Antimicrobial susceptibility was determined by disk diffusion method. PCR and DNA sequencing were performed to characterize the antimicrobial resistant genes. Of the 43 Enterobacteriaceae isolates tested, 2 isolates harbored $bla_{CTX-M-14}$ gene, and 2 and 5 strains contained qnrS and aac(6')-Ib-cr genes, respectively. A total of 43 isolates displayed a relatively lower susceptible rate ranging between 0.0 and 23.3% to most of the antimicrobial agents, except cefepime, ceftazidime, and cefaclor. We confirmed that plasmid mediated antimicrobial resistant determinants were distributed in Enterobacteriaceae isolates from chickens. Investigation of the genes and monitoring of antimicrobial resistance rate is required to prevent further spreading of antimicrobial resistant genes among Enterobacteriaceae isolates.

• Biomedical Science Letters
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• v.18 no.3
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• pp.299-306
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• 2012

Recently, the prevalence of 16S rRNA methylase conferring high-level resistance to aminoglycosides has been increasing in Gram-negative bacilli globally. We determined the prevalence and genotype of these methylase-producing bacteria, and characterized the co-resistance to ${\beta}$-lactam antibiotics and quinolone in Gram-negative clinical isolates collected in 2010 at a hospital in Korea. Among 65 amikacin-resistant isolates screened from 864 Gram-negative bacilli (GNB), 16S rRNA methylase genes were detected from 49 isolates, including Acinetobacter baumannii (43), Klebsiella pneumoniae (2), Proteus mirabilis (2) and Serratia marcescens (1), Empedobacter brevis (1). All of the 16S rRNA methylase genotype was armA and no variant sequences of amplified PCR products for armA were noted. The 16S rRNA methylase producing bacteria showed much higher resistance to aminoglycoside for Enterobacteriaceae and glucose non-fermenting (NF)-GNB and to imipenem for glucose NF-GNB, than the non-producing isolates. All of the 16S rRNA methylase producing Enterobacteriaceae had the extended-spectrum-${\beta}$-lactamase. In addition, two K. pneumoniae concurrently produced both plasmid-mediated AmpC ${\beta}$-lactamase and qnrB gene. All of the amikacin-resistant A. baumannii (43) co-harbored armA 16S rRNA methylase and $bla_{OXA-23}$ carbapenemase. In conclusion, 16S rRNA methylase producing bacteria were very prevalent among GNB in South Korea, and were commonly associated with co-resistance, including carbapenem and quinolone.