• Journal of Microbiology
• /
• 제43권2호
• /
• pp.209-212
• /
• 2005

The purpose of this study was to develop species-specific PCR primers for use in the identification and detection of Actinobacillus actinomycetemcomitans. These primers target variable regions of the 168 ribosomal RNA coding gene (rDNA). We assessed the specificity of the primers against 9 A. actinomycetemcomitans strains and 11 strains (3 species) of the Haemophilus genus. Primer sensitivity was determined by testing serial dilutions of the purified genomic DNAs of A. actinomycetemcomitans ATCC$ 33384^$T Our obtained data revealed that we had obtained species-specific amplicons for all of the tested A. actinomycetemcomitans strains, and that none of these amplicons occurred in any of the other species. Our PCR protocol proved able to detect as little as 4 fg of A. actinomycetemcomitans chromosomal DNA. Our findings suggest that these PCR primers are incredibly sensitive, and should prove suitable for application in epidemiological studies, as well as the diagnosis and monitoring of periodontal pathogens after treatment for periodontitis.

• Environmental Engineering Research
• /
• 제14권2호
• /
• pp.120-125
• /
• 2009

Water stress has become a major concern in agriculture. Korea suffers from limited agricultural water supply, and wastewater reuse has been recommended as an alternative solution.A study was performed to examine the effects of microorganism concentration in the ponded-water of a paddy rice field with reclaimed-water irrigation for evaluating the microbial risk to farmers and neighborhoodchildren.Most epidemiological studies were performed based on an upland field, and they may not directly applicable to paddy fields. Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion. Their risk value increased significantly high level after irrigation and precipitation.It implies that agricultural activities such as plowing, and fertilizing, and precipitation need be practiced a few days after irrigation considering health risks. The results about field application of the microbial risk assessment using E. coli showed difference according to monitoring time and treatment plot. Result of the microbial risk assessment showed that risk values of ground-water and reclaimed secondary waste water irrigation were lower than directly use of wastewater treatment plants' effluent. This paper should be viewed as a first step in the application of quantitative microbial risk assessment of E. coli to wastewater reuse in a paddy rice farming.

• 방사선산업학회지
• /
• 제9권4호
• /
• pp.181-185
• /
• 2015

Today the biosafety evaluation, a common problem of vital importance, is based on internationally proved test-systems, standards and techniques. The paradigm of biosafety includes multidisciplinary approach, a combination of physical, chemical and biological tests to monitor the environmental level of pollutants and needs to be improved by modern approaches. The genetic risk of environmental pollutions has long been studied by many researchers. In this study, used was the known sensitive plant test-system, clones of plant Tradescantia (spiderwort) able to detect gene mutations (frequency of mutational events and formation of micronuclei) in combination with chemical and, in some instances, with radiological measurements. In addition, male gametophyte generation of fruit trees was applied as bioindicators of genotoxicity. The obtained results did not show any significant increase along with wind direction. As for the male gametophyte assay, the fertility of the investigated fruit-trees near to NPP did not significantly differ from that of the control point. The influence of the NPP on the male generative system of the investigated taxa of fruit trees for the investigated year was not revealed. The system described needs to be expanded by species of interest (human) as there is a difficulty to transfer the revealed dose correlations to humans. The development of this idea includes various levels: population (epidemiological studies), individual, cellular, molecular (DNA), etc.

• 한국미생물·생명공학회지
• /
• 제48권4호
• /
• pp.564-568
• /
• 2020

Although studies on Hepatitis A virus (HAV) were crucial in the establishment of the HAV infection prevention programs, no systematic investigation into HAV has been conducted since 1999. We retrospectively analyzed the data between January 2010 to December 2018 from all the patients who underwent HAV antibody tests at the Dankook University Hospital Health Care Center. Data were collected from 56,204 individuals. Overall, 34,834 (62.0%) individuals from this cohort were positive for HAV antibodies and the annual rate of anti-HAV antibody positivity was highest in 2010 (68.5%) and lowest in 2013 (54.8%). The average decline in the antibody positivity rate was 0.62% per year, showing a statistically significant difference (p < 0.001). In the over 40s age group, anti-HAV antibody positivity rates decreased from 89% in 2010 to 64% in 2018 (p < 0.001), with an annual decrease of 3.1%. In the over 30s age group, it decreased from 48.2% in 2010 to 34.7% in 2018 (p < 0.001), with an annual decrease of 1.82%. This study shows that the antibody positivity rate is decreasing across age groups but given that HAV infection poses more significant risks in older patients it is important to expand the evaluations of the current and future antibody positivity rates for HAV in various age groups.

• 한국환경보건학회지
• /
• 제45권5호
• /
• pp.434-442
• /
• 2019

Objectives: This study was performed in order to report the epidemiological features of a food poisoning outbreak caused by multiple pathogens in a high school in Chungcheongnam-do Province, Korea in April 2019 and to suggest measures to prevent a similar incidence. Methods: A total of 39 patients with diarrhea were examined. Environmental samples were obtained from 6 food handlers, 4 food utensils, 72 preserved foods served during the food poisoning outbreak, 9 door handles, 10 drinking water samples from water dispensers, and 6 ground water samples from water taps. These analyzed to detect viruses and bacteria. Results: Among the 39 patients, 21 cases (53.8%) of enteroaggregative E. coli (EAEC), 7 cases of Staphylococcus aureus (17.9%), and 17 cases of norovirus (43.6%) were positive, and in 16 of the cases a co-infection with at least one other pathogen were observed. EAEC was assumed to be transmitted from contaminated drinking water because it was also detected in the water sample from a water dispenser in the dormitory. Staphylococcus aureus was isolated only in the fecal samples of patients, meaning it was not possible to trace its origin. The genotype of norovirus detected in the drinking water and ground water was consistent with that isolated from patients, and it was determined that the norovirus infection originated from the school's water environment. Conclusions: These findings indicate that a lack of environmental hygiene management related to school meals caused the food poisoning incident. In particular, a lack of management of drinking water, water supply, and personal hygiene should be pointed out. This should be urgently addressed and continuous monitoring should be carried out in the future. In addition, students and staff should be educated and trained to improve their personal hygiene.

• Parasites, Hosts and Diseases
• /
• 제59권5호
• /
• pp.507-512
• /
• 2021

Since 1993, vivax malaria has been recognized as a public health burden in Korea. Despite of pan-governmental malaria-control efforts and the dramatic reduction in the burden of this disease over the last 10 years, vivax malaria has not been well controlled and has remained continuously endemic. We focused interviewed and examined the charts of 28 confirmed vivax malaria patients given malarial therapy for whom daily records were kept from Gimpo-si, Gyeonggi-do of Korea. Various epidemiological characteristics of vivax malaria, including the incubation period, medication used, and recurrence, and an evaluation of the parasitic characteristics from the focused interviews of patients from this region are described here. Most of the participants indicated the 3 most common symptoms of malaria (headache, chills and fever). Of the 28 cases, 2 experienced a second attack and there were 17 and 11 cases with short- and long-term incubation periods, respectively, yielding a short-term to long-term ratio of 1.5. Based on the parasitemia stages, most of the participants were tested at 5 to 7 days (11 cases) and 7 to 15 days (11 cases) after initial wave of asexual parasites. In conclusion, public health authorities should consider developing management measures to decrease the time lag for diagnosis and drafting unified and robust guidelines for drug use for malaria and drawing up unified and robust guidelines on the use of medication for malaria. It also suggests that routine monitoring, surveillance, and precise medical surveys in high-risk vivax malaria endemic areas are pivotal to controlling this persistent public disease and finally eliminating it from Korea.

• 대한임상검사과학회지
• /
• 제50권4호
• /
• pp.406-413
• /
• 2018

최근 P. aeruginosa의 carbapenem에 대한 내성은 전 세계적으로 증가하고 있는 실정이다. 특히 $metallo-{\beta}-lactamases$ (MBLs)는 carbapenem의 고도 내성에 관여하고 있는 것으로 보고되고 있다. 한편, Sequence type 235 (ST235)는 다제내성 클론으로써 국제적으로 보고되고 있으며, IMP-6와 VIM-2 유전자의 확산에도 관여하는 것으로 알려져 있다. 본 연구에서는 2008년 3월부터 2014년 6월까지, 대전지역의 3차 병원에서 분리된 carbapenem 내성 P. aeruginosa에서 MBL 유전자를 분석하고 이에 대한 역학관계를 조사하고자 하였다. 항균제 감수성 양상은 디스크 확산법으로 확인하였고, MBL 유전자의 분석을 위해 PCR과 염기서열분석을 수행하였다. 더불어, 역학 관계를 조사하기 위해 multilocus sequence typing (MLST)를 실시하였다. 110 균주의 carbapenem 내성 P. aeruginosa 중, 32균주(29.1%)가 MBL를 생성하였고, IMP-6 (29균주, 90.6%)가 주요하게 확인되었다. VIM-2는 3균주(9.4%)에서 확인되었으며, 모두 ST357로 확인되었다. IMP-6를 생성하는 P. aeruginosa는 모두 다제내성을 보였고, ST235로 확인되었다. ST235 (55균주, 50.0%)는 가장 높은 비율로 확인된 클론이며 7년 동안 지속적으로 확인되었다. 이러한 다제내성 ST235의 확산을 방지하기 위해, carbapenem의 과도한 사용을 제한하고, 지속적으로 모니터링하는 전략이 개발되어야 할 것으로 사료된다.

• 대한임상검사과학회지
• /
• 제53권3호
• /
• pp.217-224
• /
• 2021

전 세계적으로 fluoroquinolone (FQ) 내성 그람음성균이 출현하고 있는 가운데, 최근 우리나라에서 FQ 내성 E. coli의 증가 추세는 심각한 우려를 낳고 있다. 이에 본 연구에서는 2018년 6월부터 12월까지 대전지역의 3차 병원에서 분리된 ciprofloxacin 내성 E. coli 56균주를 대상으로, 역학관계와 FQ 내성 결정인자의 양상을 조사하였다. 역학관계를 확인하기 위해 multilocus sequence typing (MLST)을 실시하였다. PCR과 염기서열 분석은 gyrA, gyrB, parC, parE 유전자의 QRDR에서 염색체상의 돌연변이와 aac(6)-Ib-cr, qepA, qnrA, qnrB, qnrC, qnrD 및 qnrS와 같은 PMQR 유전자의 빈도를 확인하였다. MLST 분석 결과, 12개의 ST를 확인하였으며, 이 중 가장 우세한 ST는 ST131 (31/56, 55.4%)이었고, 순차적으로 ST1193 (13/56, 23.2%), ST405 (3/56, 5.4%)의 결과를 보였다. ciprofloxacin 내성 E. coli 56균주 중 gyrA 유전자에서 83번째 아미노산인 serine (S)이 leucine (L)으로, 87번째 아미노산인 aspartic acid (D)가 asparagine (N)으로 치환되고, parC 유전자에서 80번째 아미노산인 serine (S)이 isoleucine (I)으로, 84번째 아미노산인 glutamic acid (E)가 valine (V)으로 치환된 결과(29/56, 51.8%)가 가장 빈번하게 확인되었고, aac(6)-Ib-cr (19/56, 33.9%)은 가장 흔한 PMQR 유전자로 확인되었다. 이러한 FQ 내성 결정인자의 결과는 다른 클론과 비교하여 ST131에서 더 빈번하게 확인되었다. ciprofloxacin 내성 E. coli 균주에 대한 역학적 특성의 지속적인 모니터링과 FQ 내성 결정인자에 대한 추가 연구가 필요할 것으로 사료된다.

• 대한임상검사과학회지
• /
• 제54권4호
• /
• pp.265-272
• /
• 2022

Carbapenemase 생성 장내 세균(carbapenemase-producing Enterobacteriaceae, CPE) 중 특히 KPC-2 생성 Klebsiella pneumoniae의 출현과 확산은 전 세계적으로 급격히 증가하고 있으며, 심각한 공중 보건 위협이 되고 있다. 이러한 KPC-2 생성 K. pneumoniae의 역학과 특징은 지역 및 기간에 따라 다르기 때문에, 본 연구에서는 2017년 3월부터 2020년 12월까지 대전지역의 3차 병원에서 분리된 carbapenem 내성 K. pneumoniae (carbapenem-resistant K. pneumoniae, CRKP) 78 균주를 대상으로 carbapenemase 유전자를 분석하고, 이에 대한 역학 관계를 조사하였다. 항균제 감수성 양상은 디스크 확산법으로 확인하였고, carbapenemase 유전자의 분석을 위해 PCR과 DNA 염기서열분석을 수행하였다. 또한, 역학관계는 MLST (multilocus sequence typing)를 통해 조사하였다. 78 균주의 CRKP 중 35 균주(44.9%)가 carbapenemase 생성 K. pneumoniae였으며, 주요 carbapenemase 유형은 KPC-2 (30주, 85.7%)로 확인되었다. NDM-1과 NDM-5는 각각 4 균주(11.4%)와 1 균주(2.9%)에서 확인되었다. MLST 분석에서 10개의 sequence type (ST)이 확인되었고, 가장 흔한 ST는 ST307 (51.4%, 18/35)이었다. ST307 균주는 모두 KPC-2 생성 K. pneumonia였고, 다제내성으로 확인되었다. 또한, ST307은 4년 동안 지속적으로 출현하였다. 이러한 결과는 KPC-2 생성 K. pneumoniae ST307의 확산을 방지하기 위해 지속적인 모니터링과 적절한 감염 관리가 필요할 것으로 사료된다.

• BMB Reports
• /
• 제29권2호
• /
• pp.105-110
• /
• 1996

Polyclonal antiserum R101 against aflatoxin $B_1$ ($AFB_1$) was raised in New Zealand white rabbits after injection of bovine serum albumin-$AFB_1$ conjugate. Competitive ELISA (enzyme linked immuno-sorbent assay) demonstrated that antiserum R101 has the highest binding for $AFB_1$ (50% inhibition at 170 fmol) and aflatoxicol II (50% inhibition at 112 fmol). It also reacts with other aflatoxins such as $AFB_2$, $AFG_1$, $AFG_2$, and aflatoxin metabolites ($AFM_1$, $AFM_2$, $AFP_1$, and $AFQ_1$), but it does not cross-react with $AFG_2a$. Using this antiserum, aflatoxins were quantitated in 100 urine samples of undergraduate students at the College of Pharmacy, Sung Kyun Kwan University, Republic of Korea. By ELISA, $AFB_1$ and its metabolites were detected in human urine samples (N=100, male=89, female=11, ages=20~31 yrs) with a range of 1.4~200.6 ng/kg/day (mean$\pm$SD=$18.11{\pm}33.01\;ng\;AFB_1/kg/day$ in males, $3.82{\pm}2.65\;ng/kg/day$ in females). Assuming that urinary excretion is about 7.6% of $AFB_1$ intake (Groopman et al., 1992), we estimated that Koreans were daily exposed to a total dietary $AFB_1$ of $240.20{\pm}438.67\;ng/kg/day$ in males and $50.35{\pm}29.88\;ng/kg/day$ in females, respectively. When the human monitoring data was applied to a linear regression model of Y=21.67X-10.04 {Y=liver cancer incidence per 100,000, X=Log $AFB_1$ intake (ng/kg/day), r=0.99} developed from previously reported epidemiological data, calculated liver cancer incidences attributed to $AFB_1$ exposure were 41.56/100,000 in males and 26.84/100,000 in females. The incidences were similarly correlated with liver cancer mortality rates of 43.43/100,000 in males and 11.23/100,000 in females in Korea. These results suggest that aflatoxin exposure may be an important risk factor for the high incidence of liver cancer in Korea.