Concurrent treatment with ursolic acid and low-intensity treadmill exercise improves muscle atrophy and related outcomes in rats.

The objective of this study was to analyze the concurrent treatment effects of ursolic acid (UA) and low-intensity treadmill exercise and to confirm the effectiveness of UA as an exercise mimetic to safely improve muscle atrophy-related diseases using Sprague-Dawley (SD) rats with skeletal muscle atrophy. Significant muscle atrophy was induced in male SD rats through hind limb immobilization using casting for 10 days. The muscle atrophy-induced SD rats were group into four: SED, sedentary; UA, daily intraperitoneal UA injection, 5 mg/kg; EX, low-intensity (10-12 m/min, 0° grade) treadmill exercise; and UEX, daily intraperitoneal UA injection, 5 mg/kg, and low-intensity (10-12 m/min, 0° grade) treadmill exercise. After 8 weeks of treatment, endurance capacity was analyzed using a treadmill, and tissues were extracted for analysis of visceral fat mass, body weight, muscle mass, expression of muscle atrophy- and hypertrophy-related genes, and endurance capacity. Although the effects of body weight gain control, muscle mass increase, and endurance capacity improvement were inadequate in the UA group, significant results were confirmed in the UEX group. The UEX group had significantly reduced body weight and visceral fat, significantly improved mass of tibialis anterior and gastrocnemius muscles, and significantly decreased atrophy-related gene expression of MuRF1 and atrogin-1, but did not have significant change in hypertrophy-related gene expression of Akt and mTOR. The endurance capacity was significantly improved in the EX and UEX groups. These data suggest that concurrent treatment with low-intensity exercise and UA is effective for atrophy-related physical dysfunctions.

Subtype specific virus enrichment with immunomagnetic separation method followed by NGS unravels the mixture of H5 and H9 avian influenza virus.

Wild bird avian influenza type A virus (AIV) surveillance is important for the early detection of highly pathogenic AIVs and for providing early warnings to the poultry industry and veterinary services to implement more effective control measures against these viruses. Some field samples are often found to contain more than two kinds of AIV. Correct determination of the HA/NA subtype and complete nucleotide sequences of the component viruses in those samples are often critical for timely and accurate understanding of the field situation, but it is not easy to define the genomic structure of the constituent viruses unambiguously because AIV has eight segmented genomes. In this study, with immunomagnetic beads incorporating polyclonal antibodies of chicken for subtype-specific viral enrichment, we could selectively decrease the density of one of the two constituent viruses in a sample of different subtypes, H5 and H9, artificially generated; this was represented in the changes of Ct values with subtype specific real-time RT-PCR. Following this, with NGS, we could recover nearly complete genomic sequences and arrange the consensus sequences of gene segments of the constituent viruses confidently with the quantitative variable like genome coverage, linked along the gene segments and associated with the number of viral copies in a sample.

Development of a Novel Korean H9-Specific rRT-PCR Assay and Its Application for Avian Influenza Virus Surveillance in Korea.

Since the 2000s, the Y439 lineage of H9N2 avian influenza virus (AIV) has been the predominant strain circulating in poultry in Korea; however, in 2020, the Y280 lineage emerged and spread rapidly nationwide, causing large economic losses. To prevent further spread and circulation of such viruses, rapid detection and diagnosis through active surveillance programs are crucial. Here, we developed a novel H9 rRT-PCR assay that can detect a broad range of H9Nx viruses in situations in which multiple lineages of H9 AIVs are co-circulating. We then evaluated its efficacy using a large number of clinical samples. The assay, named the Uni Kor-H9 assay, showed high sensitivity for Y280 lineage viruses, as well as for the Y439 lineage originating in Korean poultry and wild birds. In addition, the assay showed no cross-reactivity with other subtypes of AIV or other avian pathogens. Furthermore, the Uni Kor-H9 assay was more sensitive, and had higher detection rates, than reference H9 rRT-PCR methods when tested against a panel of domestically isolated H9 AIVs. In conclusion, the novel Uni Kor-H9 assay enables more rapid and efficient diagnosis than the "traditional" method of virus isolation followed by subtyping RT-PCR. Application of the new H9 rRT-PCR assay to AI active surveillance programs will help to control and manage Korean H9 AIVs more efficiently.

Influencing factor of COVID-19 vaccination trust and hesitancy in Wonju city, South Korea.

Social capital (SC) has been documented to effectively reduce the spread of diseases, including COVID-19; however, research pertaining to SC and COVID-19 vaccination in Korea is lacking. This cross-sectional study conducted in the city of Wonju, Gangwon Province, Korea (n = 1,096) examined the differences in COVID-19 vaccine trust and hesitancy considering individual characteristics and investigated the effects of SC on COVID-19 vaccine trust and hesitancy. SC was measured based on 14 items pertaining to social trust, network, and norms. Responses regarding COVID-19 screening history, vaccine trust, and vaccine hesitancy were also assessed. SC scores did not differ between sexes, but differed significantly according to age and household income; thus, adults aged 70-79 years had the highest SC scores, and mean SC score increased significantly with income. COVID-19 vaccine trust differed significantly according to age, average household income, social organization involvement, and SC score. COVID-19 vaccine hesitancy differed significantly with age, SC score, and COVID-19 screening history. In univariate logistic regression, age, average household income, social organization involvement, and SC score were significant predictors of vaccine trust; in multivariable analysis, however, the identified predictors were age and SC. In particular, people with an SC score ≥50 were 2.660 times more likely to trust COVID-19 vaccines than those with lower scores. In multivariable analysis, age and SC were significant predictors of vaccine hesitancy. In particular, people with an SC score ≥50 were 1.400 times more likely not to be hesitant about receiving COVID-19 vaccines than people with lower scores. These results indicate that prioritizing policies to increase SC and trust in the government could boost the COVID-19 vaccination rate.

Which Group Should be Vaccinated First?: A Systematic Review.

BACKGROUND: Since the supply of coronavirus disease 2019 (COVID-19) vaccines will be limited worldwide, it is essential to prioritize vaccination based on scientific evidence. Although several frameworks and studies on vaccine distribution have been published, no published systematic review has evaluated the prioritization of the COVID-19 vaccine. MATERIALS AND METHODS: We searched 4 different databases, PubMed, SCOPUS, Web of Science, and EMBASE for articles published between January 2019 and December 31, 2020. Studies were included if they contained the primary search terms "vaccine", "COVID-19", and "prioritization". In addition, we manually included reports from national and international websites. RESULTS: Thirteen studies met the inclusion criteria. In these studies, older adults were the most frequently mentioned group, and healthcare workers (HCWs) were mentioned as the 1st priority group. HCWs and patients with comorbidities were the 2nd and 3rd most frequently mentioned groups in the reviewed papers. Reducing severe COVID-19 was the most frequently mentioned goal. CONCLUSION: Since vaccination programs have been initiated in several countries, scientific evidence on vaccination prioritization is needed to increase our knowledge of general vaccine prioritization and improve vaccine acceptance. Our results showed that HCWs and older adults were the most frequently valued in studies.

Detection of Linezolid-Resistant Enterococcus faecalis and Enterococcus faecium Isolates from the Layer Operation System in Korea.

Linezolid (LNZ) is one of the most important antimicrobial agents against infections caused by gram-positive bacteria, including enterococci. In a layer operation system, antimicrobial resistance can be transferred to commercial layers via the fecal-oral route. This study investigated the presence and distribution of LNZ-resistant Enterococcus faecalis and Enterococcus faecium in a layer operation system. Among 117 E. faecalis and 154 E. faecium, 10 (8.5%) E. faecalis and 5 (3.2%) E. faecium isolates showed resistance to LNZ and chloramphenicol, and they exhibited multidrug resistance against 5 or more classes of antimicrobial agents. Among the resistant isolates, 9 (90.0%) and 2 (20.0%) E. faecalis harbored optrA and cfr genes, respectively. The optrA and fexA genes were not detected in five LNZ-resistant E. faecium. None of the 15 LNZ-resistant isolates harbored the fexA gene, and no mutations were observed in the genes encoding domain V of 23S ribosomal RNA (rRNA) and ribosomal proteins L3 (rplC) and L4 (rplD). Transferability was identified in three of the nine optrA-positive LNZ-resistant isolates. The tetM, tetL, and ermB genes were cotransferred with the optrA gene in all optrA-positive transconjugants. The results indicate that optrA is well-distributed in E. faecalis, implying a greater level of transferability. Thus, enhanced surveillance efforts are needed to monitor the emergence and spread of optrA in enterococci in layer operation system.

COVID-19 Vaccine Perception in South Korea: Web Crawling Approach.

BACKGROUND: The US Centers for Disease Control and Prevention and the World Health Organization emphasized vaccination against COVID-19 because physical distancing proved inadequate to mitigate death, illness, and massive economic loss. OBJECTIVE: This study aimed to investigate Korean citizens' perceptions of vaccines by examining their views on COVID-19 vaccines, their positive and negative perceptions of each vaccine, and ways to enhance policies to increase vaccine acceptance. METHODS: This cross-sectional study analyzed posts on NAVER and Instagram to examine Korean citizens' perception of COVID-19 vaccines. The keywords searched were "vaccine," "AstraZeneca," and "Pfizer." In total 8100 posts in NAVER and 5291 posts in Instagram were sampled through web crawling. Morphology analysis was performed, overlapping or meaningless words were removed, sentiment analysis was implemented, and 3 public health professionals reviewed the results. RESULTS: The findings revealed a negative perception of COVID-19 vaccines; of the words crawled, the proportion of negative words for AstraZeneca was 71.0% (476/670) and for Pfizer was 56.3% (498/885). Among words crawled with "vaccine," "good" ranked first, with a frequency of 13.43% (312/2323). Meanwhile, "side effect" ranked highest, with a frequency of 29.2% (163/559) for "AstraZeneca," but 0.6% (4/673) for "Pfizer." With "vaccine," positive words were more frequently used, whereas with "AstraZeneca" and "Pfizer" negative words were prevalent. CONCLUSIONS: There is a negative perception of AstraZeneca and Pfizer vaccines in Korea, with 1 in 4 people refusing vaccination. To address this, accurate information needs to be shared about vaccines including AstraZeneca, and the experiences of those vaccinated. Furthermore, government communication about risk management is required to increase the AstraZeneca vaccination rate for herd immunity before the vaccine expires.

Determining Public Opinion of the COVID-19 Pandemic in South Korea and Japan: Social Network Mining on Twitter.

OBJECTIVES: This study analyzed the perceptions and emotions of Korean and Japanese citizens regarding coronavirus disease 2019 (COVID-19). It examined the frequency of words used in Korean and Japanese tweets regarding COVID-19 and the corresponding changes in their interests. METHODS: This cross-sectional study analyzed Twitter posts (Tweets) from February 1, 2020 to April 30, 2020 to determine public opinion of the COVID-19 pandemic in Korea and Japan. We collected data from Twitter (https://twitter.com/), a major social media platform in Korea and Japan. Python 3.7 Library was used for data collection. Data analysis included KR-WordRank and frequency analyses in Korea and Japan, respectively. Heat diagrams, word clouds, and rank flowcharts were also used. RESULTS: Overall, 1,470,673 and 4,195,457 tweets were collected from Korea and Japan, respectively. The word trend in Korea and Japan was analyzed every 5 days. The word cloud analysis revealed "COVID-19", "Shinchonji", "Mask", "Daegu", and "Travel" as frequently used words in Korea. While in Japan, "COVID-19", "Mask", "Test", "Impact", and "China" were identified as high-frequency words. They were divided into four categories: social distancing, prevention, issue, and emotion for the rank flowcharts. Concerning emotion, "Overcome" and "Support" increased from February in Korea, while "Worry" and "Anxiety" decreased in Japan from April 1. CONCLUSIONS: As a result of the trend, people's interests in the economy were high in both countries, indicating their reservations on the economic downturn. Therefore, focusing policies toward economic stability is essential. Although the interest in prevention increased since April in both countries, the general public's relaxation regarding COVID-19 was also observed.

Characteristics of linezolid-resistant Enterococcus faecalis isolates from broiler breeder farms.

Linezolid is an oxazolidinone class antibiotic used for treatment infections caused by various multidrug-resistant gram-positive pathogens including enterococci. However, recently, linezolid-resistant isolates in animals are considered as a human health hazard. In a broiler operation system, antimicrobial resistance can be transferred to the environment and commercial broiler via the fecal-oral route. Therefore, this study was conducted to investigate the prevalence and characteristics of linezolid-resistant Enterococcus faecalis (E. faecalis) from broiler parent stock in a broiler operation system. Among 297 E. faecalis isolates from 85 flocks in 8 broiler breeder farms, the prevalence of chloramphenicol- and linezolid-resistant isolates was 0 to 12.1% and 0 to 8.0%, respectively; however, there were no significant differences between farms. Therefore, a total of 14 (4.7%) chloramphenicol- and/or linezolid-resistant E. faecalis showed resistance to 7 or more antimicrobial classes. The drug-resistance gene optrA, which can confer resistance to linezolid, tedizolid, and phenicols, was found in 8 (2.69%) isolates, and 7 (2.36%) of the 8 optrA-positive isolates co-carried the phenicol exporter gene fexA. However, E. faecalis isolates from 3 of 8 broiler breeder farms only carried the optrA and/or fexA genes. As linezolid is one of the last antimicrobial treatments of choice for multidrug-resistant gram-positive pathogens including E. faecalis, the presence of antibiotic-resistant E. faecalis in broiler breeder farms should be monitored to prevent the introduction of linezolid-resistant strains to the food chain.

Antimicrobial resistance monitoring of commensal Enterococcus faecalis in broiler breeders.

Enterococcus faecalis (E. faecalis) has rapidly acquired resistance to multiple antimicrobials, and the antimicrobial resistance of E. faecalis from broiler breeders has been implicated in its vertical transmission to their offspring. The objective of this study was to investigate the antimicrobial resistance and genetic diversity of commensal E. faecalis isolated from the broiler breeder farms. Among a total of 229 E. faecalis isolates from 9 broiler breeder farms, the highest resistance rate was observed in tetracycline (78.2%), followed by doxycycline (58.1%) and erythromycin (43.7%), and the prevalence of antimicrobial resistance showed significant differences among the 9 broiler breeder farms (P < 0.05). The tetM gene (77.1%) and ermB gene (85.0%) were detected at the highest levels in 179 TE-and 100 E-resistant isolates, respectively. Twenty-four high-level gentamicin-resistant isolates carried aac(6″)Ie-aph(2″)-la gene, and 9 high-level ciprofloxacin-resistant isolates showed point mutations in both gyrA and parC genes. All high-level gentamicin-resistant or high-level ciprofloxacin-resistant isolates showed one of the two different virulence gene patterns, ace-asa1-efaA-gelE complex or ace-efaA-gelE complex. These results indicate that constant epidemiological monitoring at the breeder level is required to prevent the pyramidal transmission of antimicrobial-resistant E. faecalis.

Molecular characterization of avian pathogenic Escherichia coli from broiler chickens with colibacillosis.

Avian pathogenic Escherichia coli (APEC) causes extensive mortality in poultry flocks, leading to extensive economic losses. The aim of this study was to investigate the phenotypic and genotypic characteristics and antimicrobial resistance of recent APEC isolates. Of the 79 APEC isolates, the most predominant serogroup was O78 (16 isolates, 20.3%), followed by O2 (7 isolates, 8.9%) and O53 (7 isolates, 8.9%). Thirty-seven (46.8%) and six (7.6%) of the isolates belonged to phylogenetic groups D and B2, respectively, and presented as virulent extraintestinal E. coli. Among 5 analyzed virulence genes, the highest frequency was observed in hlyF (74 isolates, 93.7%), followed by iutA (72 isolates, 91.9%) gene. The distribution of the iss gene was significantly different between groups A/B1 and B2/D (P < 0.05). All group B2 isolates carried all 5 virulence genes. APEC isolates showed high resistance to ampicillin (83.5%), nalidixic acid (65.8%), tetracycline (64.6%), cephalothin (46.8%), and ciprofloxacin (46.8%). The ß-lactamases-encoding genes blaTEM-1 (23 isolates, 29.1%), blaCTX-M-1 (4 isolates, 5.1%), and blaCTX-M-15 (3 isolates, 3.8%); the aminoglycoside-modifying enzyme gene aac(3)-II (4 isolates, 5.1%); and the plasmid-mediated quinolone genes qnrA (10 isolates, 12.7%) and qnrS (2 isolates, 2.5%) were identified in APEC isolates. The tetA (37 isolates, 46.8%) and sul2 (20 isolates, 25.3%) were the most prevalent among tetracycline and sulfonamide resistant isolates, respectively. This study indicates that APEC isolates harbor a variety of virulence and resistance genes; such genes are often associated with plasmids that facilitate their transmission between bacteria and should be continuously monitored to track APEC transmission in poultry farms.

Molecular characteristics of fluoroquinolone-resistant avian pathogenic Escherichia coli isolated from broiler chickens.

Avian pathogenic Escherichia coli (APEC) is a major pathogen in the poultry industry worldwide including Korea. In this study, the phenotypic and genotypic characteristics of 33 fluoroquinolone (FQ)-resistant APEC isolates from broilers were analyzed. All FQ-resistant APEC isolates showed amino acid exchanges at both gyrA and parC and high minimal inhibitory concentrations for FQs. A total of 11 (33.3%) isolates were positive for the plasmid-mediated quinolone resistance (PMQR) genes, qnrA (8 isolates) and qnrS (3 isolates), and showed multidrug resistance. Among the 11 PMQR-positive isolates, 1 and 2 isolates carried blaCTX-1 and blaCTX-15, respectively, as extended-spectrum ß-lactamase (ESBL) producers, and the non-ESBL gene, blaTEM-1, was found in 4 isolates. Among 3 aminoglycoside-resistant isolates, aac(3)-II was only detected in 1 isolate. All 8 APEC isolates with resistance to tetracycline carried the tetA gene. Overall, 6 of the 7 trimethoprim-sulfamethoxazole-resistant isolates carried the sul1 or sul2 genes, while only 2 of the 8 chloramphenicol-resistant isolates carried the catA1 gene. Although 9 isolates carried class I integrons, only 4 isolates carried the gene cassettes dfrA12-aadA2 (2 isolates), dfrA17-aadA5 (1 isolate), extX-psp-aadA2 (1 isolate), and dfrA27 (1 isolate). The most common plasmid replicon was FIB (8 isolates, 72.7%), followed by K/B (4 isolates, 36.4%). Antimicrobial resistance monitoring and molecular analysis of APEC should be performed continuously to surveil the transmission between poultry farms.

Effects of ursolic acid on muscle mass and bone microstructure in rats with casting-induced muscle atrophy.

PURPOSE: Recent studies suggest that ursolic acid (UA) is a potential candidate for a resistance exercise mimetic that can increase muscle mass and alleviate the deleterious effect of skeletal muscle atrophy on bone health. However, these studies evaluated the effects of UA on skeletal muscle and bone tissues, and they have not verified whether such effect could occur concurrently on muscle and bone, as is the case with resistance exercise. Thus, the aim of this study was to analyze the effect of UA injection on muscle mass and bone microstructure using an animal model of atrophy to demonstrate the potential of UA as a resistance exercise mimetic. METHODS: The immobilization (IM) method was used on the left hindlimb of Sprague Dawley (SD) rats for 10 days to induce muscle atrophy, whereas the right hindlimb was used as an internal control (IC). The animal models were divided into two groups, SED (sedentary, n=6) and UA (n=6) to demonstrate the effect of UA on atrophic skeletal muscles. The UA group received a daily intraperitoneal injection of UA (5 mg/kg/day) for 8 weeks. After 10 days of IM, the data collected for the IC were compared with that of IM to determine whether muscle atrophy might occur. RESULTS: Muscle atrophy was induced and bone mineral density (BMD) decreased significantly. The 8-week UA treatment significantly increased the gastrocnemius muscle mass compared to the SED group. In regard to the effect of UA on bones, negative results such as a decrease in BMD, trabecular bone volume fraction, and trabecular number, and an increase in trabecular separation, were observed in the SED group, but no such difference was observed in the UA group. No significant difference was observed in atrophic hindlimbs between SED and UA groups. CONCLUSION: These results alone are insufficient to suggest that UA is a potential resistance exercise mimetic for atrophic skeletal muscle and weakened bone. However, this study will help determine the potential of UA as a resistance exercise mimetic.

Genetic characterization of high-level aminoglycoside-resistant Enterococcus faecalis and Enterococcus faecium isolated from retail chicken meat.

Retail chicken meat can play a role in the transfer of drug resistance to humans through the handling or ingestion of improperly cooked meat contaminated with resistant enterococci. In fact, high-level aminoglycoside-resistance (HLAR) in enterococci identified in human cases. Therefore, the prevalence and genetic characterization of HLAR in enterococci in retail chicken meat were investigated in this study. Of the 345 enterococci strains, 29 (8.7%) showed HLAR. All HLAR in enterococci carried at least 1 of 2 aminoglycoside-modifying enzyme genes, aac(6')Ie-aph(2″)-Ia and ant(6)-Ia. Among the 13 isolates that carried aac(6')Ie-aph(2″)-Ia, 3 had pattern A, with IS256 at both ends, and the other 10 had pattern D, without IS256 at both ends. All HLAR in enterococci also showed multidrug resistance. Among the 24 erythromycin-resistant enterococci, 19 (79.2%) harbored the ermB gene, and one (4.2%) harbored both the ermB and ermA genes. A total of 21 enterococci were tetracycline-resistant and harbored one or more of the following tetracycline resistance genes tet(M), tet(L), and tet(O). The Int-Tn gene was detected in one isolate (3.4%) carrying the tet(M) and ermB genes. All 4 chloramphenicol-resistant isolates carried either the phenicol resistance gene cfr alone (one isolate), both cfr and fexA (one isolate), or both fexA and optrA (2 isolates). Four efflux pump genes, efr(A), efr(B), emeA, and lsa, were detected in all HLAR in Enterococcus faecalis isolates. These results improve our understanding of the transmission dynamics of HLAR in enterococci from non-hospital sources to humans.

Antimicrobial Resistance and Genetic Diversity of Salmonella Serotypes Recovered from Edible Pork Offal from Korea.

Although edible offal can be easily contaminated with foodborne bacteria and regarded as important transfers of antimicrobial resistance to humans, the characterization of bacteria from edible offal have not been researched sufficiently. This study is the first to focus on the molecular characterization of Salmonella isolated from edible pork offal. From a total of 52 Salmonella isolates from edible pork offal, 44 (80.7%) were resistant to at least one antimicrobial agent and 24 (46.2%) exhibited multidrug resistance (MDR). All MDR Salmonella were also resistant to ß-lactams and 12 (50.0%) of the isolates were positive for blaTEM-1. Eleven (68.8%) of the 16 gentamicin-resistant isolates harbored the ant(2'')-I gene. Among 18 tetracycline-resistant isolates, tetA and tetB genes were found in 9 (50.0%) and 3 (16.7%) isolates, respectively. The sul1 gene was identified in 9 (81.8%) of 11 trimethoprim/sulfamethoxazole-resistant isolates, and the cmlA gene was identified in only 2 (18.1%) among 11 chloramphenicol-resistant isolates. Eighteen (75.0%) of the 24 MDR Salmonella were identified as containing class 1 integrons, within which dfrA12-aadA2 (55.6%) was the most prevalent resistance gene cassettes. Twenty-one (87.5%) of the MDR isolates were also found to have the plasmid replicons. Replicon B/O (41.7%) was the most prevalent replicon types. These results suggest that edible pork offal can become a reservoir that not only harbors MDR Salmonella, but also contributes to their dissemination through cross-contamination processes.

Molecular Characterization of Multidrug-Resistant Escherichia coli Isolates from Edible Offal in Korea.

HIGHLIGHTS: Edible offal is significantly contaminated by antimicrobial-resistant Escherichia coli. E. coli from edible offal is harboring various antimicrobial resistance and virulence genes. Improvements in hygienic conditions of edible offal production is required.

Molecular characterization of antimicrobial-resistant Enterococcus faecalis and Enterococcus faecium isolated from layer parent stock.

Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) are ubiquitous intestinal bacteria in humans and animals that can easily acquire antimicrobial resistance, which allows them to have roles as antimicrobial resistance indicators. In addition, layer parent stock produces thousands of eggs for the production of commercial laying hens and can transfer a variety of viral and bacterial agents to chicks. The objective of this study was to determine the prevalence and characteristics of antimicrobial-resistant E. faecalis and E. faecium isolated in the layer parent stock level of the egg-layer operating system in South Korea. A total of 129 E. faecalis and 166 E. faecium isolates from 74 flocks of 30 layer parent stock were tested for resistance in this study. The prevalence of doxycycline- (51.9%), erythromycin- (53.5%), high-level gentamicin- (13.2%), high-level kanamycin- (31.0%), high-level streptomycin- (30.2%), and tetracycline- (64.3%) resistant E. faecalis isolates were higher than those for E. faecium isolates (P < 0.05). The ermB gene was detected in 66 (95.7%) erythromycin-resistant E. faecalis isolates, which was higher than that of 32 (71.7%) erythromycin-resistant E. faecium isolates. Twenty-one high-level gentamicin-resistant Enterococcus spp. (17 E. faecalis and 4 E. faecium) carried at least one aminoglycoside-modifying enzyme gene, aac(6')Ie-aph(2')-Ia or ant(6)-Ia. Fourteen isolates that harbored both aac(6')Ie-aph(2')-Ia and ant(6)-Ia exhibited pattern A with IS256 at both ends. Ten high-level ciprofloxacin-resistant Enterococcus spp. (8 E. faecalis and 2 E. faecium) showed amino acid changes from serine to isoleucine at codons 83 in gyrA, and 80 in parC. Also, the virulence genes ace, asa1, efaA, and gelE were detected in this study. To the best of our knowledge, this is the first study to examine the prevalence and characteristics of antimicrobial-resistant E. faecalis and E. faecium isolates in the layer parent stock. Our findings support the need for a surveillance program to monitor the emergence of antimicrobial-resistant E. faecalis and E. faecium in layer operating system.