• Journal of Microbiology and Biotechnology
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• 제25권9호
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• pp.1460-1466
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• 2015

In this study, the prevalence of Shiga toxin-producing Escherichia coli (STEC) was investigated among raw meat or meat products from slaughterhouses and retail markets in South Korea, and their potential for antibiotic resistance and virulence was further analyzed. A total of 912 raw meats, including beef, pork, and chicken, were collected from 2008 to 2009. E. coli strains were frequently isolated in chicken meats (176/233, 75.9%), beef (102/217, 42.3%), and pork (109/235, 39.2%). Putative STEC isolates were further categorized, based on the presence or absence of the Shiga toxin (stx) genes, followed by standard O-serotyping. Polymerase chain reaction assays were used to detect the previously defined virulence genes in STEC, including Shiga toxins 1 and Shiga toxin 2 (stx1 and 2), enterohemolysin (ehxA), intimin (eaeA), STEC autoagglutination adhesion (saa), and subtilase cytotoxin (subAB). All carried both stx1 and eae genes, but none of them had the stx2, saa, or subAB genes. Six (50.0%) STEC isolates possessed the ehxA gene, which is known to be encoded by the 60-megadalton virulence plasmid. Our antibiogram profiling demonstrated that some STEC strains, particularly pork and chicken isolates, displayed a multiple drug-resistance phenotype. RPLA analysis revealed that all the stx1-positive STEC isolates produced Stx1 only at the undetectable level. Altogether, these results imply that the locus of enterocyte and effacement (LEE)-positive strains STEC are predominant among raw meats or meat products from slaughterhouses or retail markets in Korea.

• Journal of Microbiology and Biotechnology
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• 제30권12호
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• pp.1862-1869
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• 2020

The spread of plasmid-mediated colistin resistance has posed a serious threat to public health owing to its effects on the emergence of pandrug-resistant bacteria. In this study, we investigated the prevalence and characteristics of mcr-1-positive Escherichia coli isolated from retail meat samples in Korea. In total, 1,205 E. coli strains were isolated from 3,234 retail meat samples in Korea. All E. coli strains were subjected to antimicrobial susceptibility testing and were examined for the presence of mcr-1 gene. All mcr-1-positive E. coli (n = 10, 0.8%) from retail meat were subjected to pulse-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS). The transferability of mcr-1 gene was determined by conjugation assays. The mcr-1-positive strains exhibited diverse clonal types. Our mcr-1 genes were located in plasmids belonged to the IncI2 (n = 1) and IncX4 (n = 8) types, which were reported to be prevalent in Asia and worldwide, respectively. Most mcr-1 genes from mcr-1-positive strains (9/10) were transferable to the recipient strain and the transfer frequencies ranged from 2.4 × 10-3 to 9.8 × 10-6. Our data suggest that the specific types of plasmid may play an important role in spreading plasmid-mediated colistin resistance in Korea. Furthermore, our findings suggest that the retail meat may be an important tool for disseminating plasmid-mediated colistin resistance.

• 한국축산식품학회:학술대회논문집
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• 한국축산식품학회 2003년도 제31차 춘계 학술대회
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• pp.1-14
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• 2003

Lipid oxidation is one of the most important non-microbial causes of meat quality deterioration. However, there have been different/conflicting views concerning the primary catalysts of lipid oxidation in meat. This presentation provides brief overviews of lipid oxidation mechanism in general and catalysis of lipid oxidation in meat, and then focuses on inter-species differences in lipid oxidation potential, using results from our studies on meats (beef, pork and chicken) at retail and the respective meats of uniform postmortem history. The inter-species differences have highlighted the relative roles of meat pigment (myoglobin) content, catalase activity, and the concentration of oxidation substrates (particularly polyunsaturated fatty acids) in determining the lipid oxidation potential of raw meat versus cooked meat.

• 한국축산식품학회지
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• 제38권5호
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• pp.1055-1063
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• 2018

The aim of study was to investigate the correlation between the level of 17 antibiotic residues and 6 antibiotic resistances of Escherichia coli isolates in chicken meats. A total of 58 chicken meats were collected from retail grocery stores in five provinces in Korea. The total detection rate of antibiotic residues was 45% (26 out of 58). Ten out of 17 antibiotics were detected in chicken meats. None of the antibiotics exceeded the maximum residue level (MRLs) in chicken established by the Ministry of Food and Drug Safety (MFDS). The most detected antibiotics were amoxicillin (15.5%), followed by enrofloxacin (12.1%) and sulfamethoxazole (10.3%). In a total of 58 chicken meats, 51 E. coli strains were isolated. E. coli isolates showed the highest resistance to ampicillin (75%), followed by tetracycline (69%), ciprofloxacin (65%), trimethoprim/sulfamethoxazole (41%), ceftiofur (22%), and amoxicillin/clavulanic acid (12%). The results of study showed basic information on relationship between antibiotic residue and resistance for 6 compounds in 13 chicken samples. Further investigation on the antibiotic resistance patterns of various bacteria species is needed to improve food safety.

• 한국식품위생안전성학회지
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• 제32권3호
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• pp.199-205
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• 2017

인수공통 감염증의 하나인 톡소포자충의 검출을 위해서는 대부분은 ELISA 법이 사용 되고 있으나, 충체가 사멸된 후에도 양성반응이 나타나는 등 사용에 제한이 있다. 반면 유전자 검출법은 현재 감염상태를 확인 할 수 있기 때문에 식중독 원인조사 등에 적합하다고 판단되어 이를 활용하여 본 연구를 진행하였다. 톡소포자충의 유전정보를 통해 529 repeat region의 염기서열을 얻고, 프라이머 및 TaqMan 프로브를 설계하여 real-time PCR을 이용한 검출법을 개발하였다. 검출한계(lower limit of detection) 및 적정곡선을 확인한 결과 10 genomic DNA copy가 검출한계로 확인되었고, 정량을 위한 곡선은 $10^1{\sim}10^6$ DNA copies까지 0.999의 $R^2$ 값을 나타내었다. 개발된 검출법의 증폭효율을 비교하기 위해 B1 gene 타겟 프라이머 세트와 타입별 검출한계를 비교한 결과, type 1, 2, 3 톡소포자충에서 같거나 더 나은 검출한계를 보였다. 또한 식품에서 주로 분리되는 식중독 세균 14종 및 원충 3종에 대해 특이도를 비교한 결과, 모두 음성으로 나타났다. 개발된 검출법을 식육검체에 적용하였을 때 type 1, 2, 3에서 모두 원활한 검출결과를 보여 증폭방해물질이 존재하지 않은 것으로 확인되었다. 본 연구를 통해 개발된 유전자검출법은 국내 유통 중인 식육에서 인수 공통감염 원충의 하나인 톡소포자충의 감염 여부를 확인하는 사전적 모니터링의 방법으로 활용될 예정이다.

• 한국산학기술학회논문지
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• 제22권6호
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• pp.413-419
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• 2021

본 연구의 목적은 확장 스펙트럼 𝛽-락타마제(ESBL) 항생제가 그람 음성 세균에 의한 감염을 치료하고 예방하는데 사용하고 있으며 임상에서 심각한 감염을 치료하는데 선택하는 마지막 옵션 역할을 한다. 미생물의 확장 스펙트럼 𝛽-락타마제(ESBL) 및/또는 카르바페네마제(Carbapenemase) 내성에 대한 보고는 전 세계적으로 확산되는 것으로 보고되며 항생제 치료에 많은 제한을 주는 요인으로 다약재 내성과 관련이 있기 때문에 보건 서비스에 큰 관심을 가지고 있다. 본 연구는 국내 시장에서 구매하여 분리한 육류로부터 세균을 분리 동정하여 항생제 저항성 테스트인 디스크 확산법을 사용하여 내성균을 분리 실험하였고, PCR과 DNA 시퀜싱방법을 수행아였다. 결과는 PCR을 수행하여 항생제 내성유전자와 유전자를 생산하는 ESBL의 존재를 검출하고 결과를 얻었다. 총 36개의 샘플 육류로부터 181개의 각각 분리된 세균을 추출하여 실험결과을 얻었다. 결과는 PCR과 DNA 염기서열을 분석하여 항생제내성 유전자로 blaVIM, blaBIC, blaKPC, blaSIM으로 나타났다. 분리한 육류 속의 박테리아는 별도 유전자 서열분석으로 4개의 다른 박테리아가 확인되었다. 이러한 결과는 소매되는 육류에서 발견되는 박테리아에 ESBL 내성유전자인 blaVIM, blaBIC, blaKPC, blaSIM를 가진 박테리아 균주가 있을 수 있으며 이는 특수 확장 스펙트럼 𝛽-락타마제(ESBL) 및/또는 카르바페네마제(Carbapenemase) 내성유전자가 확산될 수 있다는 것을 시사한다.

• 한국축산식품학회지
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• 제29권4호
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• pp.513-522
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• 2009

HACCP is a scientific and systematic program that identifies specific hazards and gives measures for their control to ensure the safety of foods. Based on the Livestock Products Processing Act, the HACCP system is now being applied to Korean livestock products since December 1997, and Korea is accelerating its application from farm to table, including in farms, slaughterhouses, livestock product industries, retail markets, and transportation. The transport of livestock and its products is one of the vulnerable sectors in terms of food safety in Korea. Meats are transported in trucks in the form of carcasses or packaged meats in boxes. Carcasses may be exposed to microbiological, physical, and chemical hazards from the environment or through cross-contamination from other meats. Poor cleaning or maintenance of vehicles and tools may also raise the exposure of carcasses to microbiological or chemical hazards. HACCP application and its acceleration in distribution, particularly in transport, is regarded as critical to the provision to consumers of ultimately safe livestock products. To achieve this goal, steady efforts to develop practical tools for HACCP application should be carried out.

• 한국토양비료학회지
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• 제47권4호
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• pp.306-312
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• 2014

This study was carried out to develop high-performance feed using selenium-sorbed $Ca^{2+}$-exchanged zeolite A. The contents of Se increased with increasing reaction temperature and the content of $Ca^{2+}$ ions in $Ca^{2+}$-exchanged zeolite A. A synthesized high-performance feed (0.306 ppm) was applied to poultry farming for 4 and 7 weeks, respectively. Se contents in chicken meats and eggs were 18.8, 27.2, and 94.1 ppb and 73.7, 14.9, and 64.5 ppb for control (retail chicken meats), 4, and 7 weeks, respectively; Ca contents were 3.8, 9.9, and 11.9 ppm and 48.6, 48.3, and 53.6 ppm, respectively. In conclusion, Se and Ca contents in chicken meats increased as feeding periods increased, but significant differences were not observed in the eggs.

• 한국축산식품학회지
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• 제41권5호
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• pp.883-893
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• 2021

Clostridium difficile present in feces of food animals may contaminate their meats and act as a potential source of C. difficile infection (CDI) to humans. C. difficile resistance to antibiotics, its production of toxins and spores play major roles in the pathogenesis of CDI. This is the first study to evaluate C. difficile prevalence in retail raw animal meats, its antibiotics susceptibilities and toxigenic activities in Al-Jouf, Saudi Arabia. Totally, 240 meat samples were tested. C. difficile was identified by standard microbiological and biochemical methods. Vitek-2 compact system confirmed C. difficile isolates were 15/240 (6.3%). Toxins A/B were not detected by Xpect C. difficile toxin A/B tests. Although all isolates were susceptible to vancomycin and metronidazole, variable degrees of reduced susceptibilities to moxifloxacin, clindamycin or tetracycline antibiotics were detected by Epsilon tests. C. difficile strains with reduced susceptibility to antibiotics should be investigated. Variability between the worldwide reported C. difficile contamination levels could be due to absence of a gold standard procedure for its isolation. Establishment of a unified testing algorithm for C. difficile detection in food products is definitely essential to evaluate the inter-regional variation in its prevalence on national and international levels. Proper use of antimicrobials during animal husbandry is crucial to control the selective drug pressure on C. difficile strains associated with food animals. Investigating the protective or pathogenic potential of non-toxigenic C. difficile strains and the possibility of gene transfer from certain toxigenic/ antibiotics-resistant to non-toxigenic/antibiotics-sensitive strains, respectively, should be worthy of attention.

• 한국축산식품학회지
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• 제33권1호
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• pp.133-138
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• 2013

본 연구에서는 서울시내 256곳의 판매점에서 구입한 축산물 및 수산물에서 Enterococcus faecalis 와 Enterococcus facium을 분리하였으며 분리된 균주의 항생제 내성양상과 vancomycin 내성 유전자 보유여부를 검증하였다. 총 256개 시료 중 117개에서 E. faecalis(40.6%)와 E. faecium(5.1%)가 검출되어 45.7%의 분리율을 나타내었다. 축산물은 192개 중 105개 균주가 분리되어 54.7%의 분리율을 나타내었는데 닭고기에서 가장 높은 68.8%의 분리율을, 돼지고기에서 50.0%의 분리율을, 쇠고기에서 45.3%의 분리율을 나타내었다. 횟감어류에서는 18.8%의 분리율을 나타내었다. 분리된 균주에 대한 항생제 내성 양상은 10종의 항생제 디스크를 이용하여 검증하였다. Tetracycline의 내성률이 52.1%로 가장 높았으며, erythromycin의 내성률이 27.4%로 두 번째로 높게 나타났다. Ampicillin과 penicillin는 1개의 균주를 제외하고는 모두 감수성을 보였으며, amoxicillin & clavulanic acid에는 모든 균주가 감수성을 보였다. Vancomycin에는 모든 균주가 감수성을 보여 VRE는 검출되지 않았다. 분리된 균주의 vancomycin 내성유전자의 검출은 multiplex PCR을 이용하여 vanA gene과 vanB gene 보유여부를 확인하였다. vanA gene이 검출된 균주는 없었으나, vancomycin에 감수성을 나타내던 9개의 균주에서 vanB gene이 검출되어 VRE균 출현의 잠재적인 가능성을 보여주었다.