• Journal of Microbiology and Biotechnology
• /
• v.23 no.5
• /
• pp.731-737
• /
• 2013

Seventy-four Shiga toxin-producing Escherichia coli (STEC) isolates belonging to the serotype O91:H21 were isolated from 1,643 asymptomatic human carriers in a STEC outbreak at Gwangju in Korea. Although the isolates did not cause any symptoms, all of them produced Shiga toxins 1 (Stx1) and 2 (Stx2). In order to determine why these strains cause no symptoms, we explored the differences in virulence potential between the asymptomatic STEC O91:H21 isolates and symptomatic STEC O91:H21 strains (ATCC 51435 and ATCC 51434). The asymptomatic STEC O91:H21 isolates showed strongly reduced cytopathic effects compared with the symptomatic strains when intact bacterial cells were used as an inoculant. Moreover, we found a reduced adherence phenotype when testing asymptomatic strains on HeLa cells. Real-time quantitative PCR results suggest that transcriptional repression of the genes encoding type-1 fimbriae occurs in the asymptomatic isolates but not in the symptomatic strains.

• Pediatric Infection and Vaccine
• /
• v.5 no.2
• /
• pp.215-220
• /
• 1998

Purpose : Asymptomatic infections with positive throat culture for group A beta-hemolytic streptococci(GABHS) and high antistreptolysin O(ASO) concentration may lead to sequelae such as rheumatic fever or acute poststreptococcal glomerulonephritis. Children with asymptomatic infections were treated with oral penicillin V to evaluate the effectiveness of penicillin treatment on the asymptomatic infections. Methods : Throat culture and ASO concentration analysis were performed against healthy elementary school children. Thirty-six children with positive throat culture for GABHS and ASO concentrations of 400 IU/mL or more were divided into two groups. Twenty-two children were treated with oral penicillin V for 10 days, and the others were not treated. Eradication rate of GABHS and the change of ASO concentration between the two groups were compared after one month later. Results : Eradication rates of GABHS between treated and untreated children were 91%(20/22) and 50%(7/14) respectively(P<0.05). Children showing elevation of ASO levels more than 100IU/mL were 22%(4/18) in the treated group and 30%(3/10) in the untreated group, while children showing a decrease of more than 200IU/mL in the ASO level were 44%(8/18) and 40%(4/10) respectively. Conclusion : We confirmed the validity of penicillin treatment, because when we treated the asymptomatic children with penicillin V, the GABHS was eradicated effectively. But there was no significant difference of decrease in the ASO levels between the two groups due to long half-life of ASO or poor compliance. Treatment failure was 22% in terms of elevated ASO levels after penicillin treatment.

• Parasites, Hosts and Diseases
• /
• v.57 no.3
• /
• pp.233-242
• /
• 2019

Detailed description of malaria in low transmission areas is crucial for elimination. The current study aimed to provide a comprehensive description for malaria transmission in Jazan, a low transmission district, southwestern Saudi Arabia. Patients at a tertiary care hospital were recruited in our study between August 2016 and September 2018. Malaria diagnosis was performed through a species-specific nested polymerase chain reaction (nested PCR), microscopy and Paramax-$3^{TM}$ rapid detection test (RDT). Malaria was detected in 30 patients by the PCR, with point prevalence of 10.9%. Of these malaria infections, 80% was imported, 26.6% was asymptomatic and 23.3% was sub-microscopic. Malaria was reported throughout the year, with February/March and September/October peaks. Infection was significantly more in males than in females (P=0.01). Likewise, infections were detected more in febrile than in non-febrile patients (P=0.01). Adult aged 15-24 years, fever and travel were identified as high-risk factors. Malaria was primarily attributed to Plasmodium falciparum mono-infections, followed by P. vivax mono-infections and lastly to falciparum/vivax mixed infections accounting 76.6%, 16.6%, and 6.6% of PCR-confirmed malaria cases, respectively. The nested PCR was superior to the smear microscopy (sensitivity 76.6%; specificity 100%) and the RDT (sensitivity 83.3%, specificity 94.2%). The overall percent agreement between microscopy and the RDT was 92.7% (kappa=0.63). High proportion of imported malaria including sub-microscopic and sub-patent cases were described. We suggest that incorporation of molecular tool into the conventional malaria diagnosis is beneficial in Jazan district.

• Restorative Dentistry and Endodontics
• /
• v.36 no.6
• /
• pp.498-505
• /
• 2011

Objectives: The purpose of this in vivo study was to investigate the microbial diversity in symptomatic and asymptomatic canals with primary endodontic infections by using GS FLX Titanium pyrosequencing. Materials and Methods: Sequencing was performed on 6 teeth (symptomatic, n = 3; asymptomatic, n = 3) with primary endodontic infections. Amplicons from hypervariable region of the small-subunit ribosomal RNA gene were generated by polymerized chain reaction (PCR), and sequenced by means of the GS FLX Titanium pyrosequencing. Results: On average, 10,639 and 45,455 16S rRNA sequences for asymptomatic and symptomatic teeth were obtained, respectively. Based on Ribosomal Database Project Classifier analysis, pyrosequencing identified the 141 bacterial genera in 13 phyla. The vast majority of sequences belonged to one of the seven phyla: Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, Proteobacteria, Spirochetes, and Synergistetes. In genus level, Pyramidobacter, Streptococcus, and Leptotrichia constituted about 50% of microbial profile in asymptomatic teeth, whereas Neisseria, Propionibacterium, and Tessaracoccus were frequently found in symptomatic teeth (69%). Grouping the sequences in operational taxonomic units (3%) yielded 450 and 1,997 species level phylotypes in asymptomatic and symptomatic teeth, respectively. The total bacteria counts were significantly higher in symptomatic teeth than that of asymptomatic teeth (p < 0.05). Conclusions: GS FLX Titanium pyrosequencing could reveal a previously unidentified high bacterial diversity in primary endodontic infections.

• Pediatric Infection and Vaccine
• /
• v.24 no.2
• /
• pp.108-111
• /
• 2017

A 3-month-old asymptomatic infant presented with bilateral extensive consolidation of the lungs, which was diagnosed as pulmonary tuberculosis. Evaluation of the baby for tuberculosis was initiated because of a history of contact with a known tuberculosis patient. This case is interesting because the baby rarely showed symptoms during the whole course of the disease.

• Journal of fish pathology
• /
• v.23 no.1
• /
• pp.17-25
• /
• 2010

We have identified an iridovirus CH-1 from sea perch Lateolabrax sp. healthy externally and imported from China to Korea. In a comparison of the nucleotide sequences of the five different genomic regions, the CH-1 appears to be closely related to the ISKNV, IVS-1 and Ehime-1 strains detected in China, Korea and Japan respectively. In quantitative comparison of the viral DNA, level of CH-1 in tissue of imported fish was 10,000 times lower than that of IVS-1 strain presented in the infected rock bream Oplegnathus fasciatus of moribund stage. It allowed us to speculate the possibility of the asymtomatic iridovirus infection in the culturing sea perch. Such possibility of asymptomatic infection was supported by result of no appearance of dead fish with typical symptoms of iridoviral disease in keeping experiment of the imported sea pearch in laboratory for more than three weeks. Such asymptomatic infections with iridovirus were also found in spleen of the culturing and externally healthy sea perch of Korea by the presence of the iridoviral DNA in nested PCR.

• Childhood Kidney Diseases
• /
• v.28 no.2
• /
• pp.59-65
• /
• 2024

Hydronephrosis, characterized by dilation of the renal pelvis and calyces due to urine flow obstruction, poses a significant clinical challenge. Although often asymptomatic and capable of spontaneous resolution, surgical intervention is necessary for specific scenarios such as febrile urinary tract infections, deteriorating hydronephrosis, or declining renal function. The efficacy of continuous antibiotic prophylaxis in preventing urinary tract infections remains controversial. Yet, it may benefit high-risk patients, emphasizing the importance of individualized patient selection, as surgical treatment methods for patients with hydronephrosis have become less invasive than in previous decades. However, long-term follow-up outcomes are lacking, necessitating further clarification. This review presents an overview of the etiology, natural progression, and modern management of hydronephrosis, encompassing advancements in minimally invasive procedures.

• Microbiology and Biotechnology Letters
• /
• v.17 no.6
• /
• pp.634-644
• /
• 1989

Listeria monocytogenes, one of five species in the genus Listeria and the only one currently believed to be pathogenic for humans, is a small gram-positive, nonsporeforming, aerobic, motile and hemolytic rod-shaped bacterium. The bacterium is widespread in the environment, having been isolated from soil, dust, animal feed, water, sewage, almost every type of animal that has been cultured, and asymptomatic humans. L. monocytogenes causes listeriosis, a disease which most often affects humans with a compromised immune system. Included are pregnant woman, infants and adults suffering from such diseases as cancer, cirrhosis of liver or AIDS or are being treated with drugs such as corticosteroids. Listeriosis is manifested by such syndromes as pregnancy infections, granulomatosis infantiseptica, sepsis, meningoencephalitis, and focal infections. Infections, can be treated successfully with penicillin, ampicillin, or erythromycin. However, a mortality rate of about 30％ has occurred in outbreaks of listeriosis. Food-associated outbreaks of listeriosis have been attributed to coleslaw (Canada, 1981), pasteurized milk (U.S., 1983), and soft cheese (U.S., 1985). Presence of L. monocytogenes in various dairy foods has prompted recall of such products from the U.S. market-place. L. monocytogenes also has been found in raw meats and seafood.

• Journal of Medicine and Life Science
• /
• v.17 no.1
• /
• pp.29-32
• /
• 2020

As respiratory syncytial virus(RSV) is transmitted either via directly contact with an infected case or via indirectly contaminated fomites or skin, the major preventive measures are strict hand hygiene, early detection of transmitted sources, and rapid isolation of RSV patients. Especially early detection of hidden cases is the most critical control measure when an index case was notified in a postpartum center. The Guideline of Korea Centers for Diseases Control and Prevention defines potential contacts in an epidemiologic survey as admitted newborns, parents of index cases, center's workers, and visitors for 10 days before the first diagnosis day of index case. However, it needs to classify potential contacts in more detail in order to conduct a successful survey. Authors conducted to search related literatures and appraise the evidences. Firstly, potential contacts would be classified into RSV-related symptomatic contacts(SxC) and asymptomatic contacts. And then, mother, caring workers, and visitors of the index cases among asymptomatic contacts would be defined as the asymptomatic close contacts(ASCC). Finally, the rest would be defined as the asymptomatic regular contacts(ASRC). The defined test using reverse transcription-PCR is applied to SxC and ASCC, and decision of isolation or regular activities are made according to the results. The rapid antigen detection test kits are applied to ASRC. These suggestions might be helpful to detect hidden cases earlier and prevent a further infection.

• The Journal of Korean Medicine
• /
• v.42 no.1
• /
• pp.99-109
• /
• 2021

Objectives: Objective: The purpose of this study is to investigate the treatment of herbal medicine for patients with COVID-19 asymptomatic infections. Method: In English, search engines such as 'PubMed', 'Science Direct', and 'Cumulative Index to Nursing and Allied Health Literature (CINAHL)' were used. In Chinese, search engines such as 'China National Knowledge Infrastructure (CNKI)' and Wanfang were used. The keywords for the search engines were 'COVID-19', 'asymptomatic infection', 'Korean Medicine', 'traditional Chinese medicine', 'herbal medicine', and etc. Only clinical studies using herbal medicine for patients without fever or respiratory symptoms were selected. We excluded the cases that do not fit the research topic. Results: A total of 5 studies were finally selected. Among them, four of them used integrated herbal medicine and Western medicine, and one of the studies treated exclusively for herbal medicine. There were a total of seven prescriptions for herbal medicine used in the study. Outcome variables were used as following: lab test, nucleic acid conversion time, hospitalization period, chest CT, and etc. In the RCT study, herbal medicine and Western medicine decreased nucleic acid conversion time, average hospitalization time compared to the control group, but it was not statistically significant. No other adverse reactions were reported in all studies. Conclusion: According to the results, integrated herbal medicine and Western medicine might be an effective treatment for patients with COVID-19 asymptomatic infection reducing hospitalization period, time of nucleic acid turning negative. No severe adverse effects were reported. However, it is thought that better-designed research will be needed in the future.