• The Journal of the Korean Society for Microbiology
• /
• v.35 no.2
• /
• pp.129-139
• /
• 2000

Acinetobacter baumannii strains are emerging pathogens of the nosocomial infection with an increasing frequency in recent years. The therapeutic difficulty due to the wide spread of multiple resistant strains was major problem in A. baumannii infection. It seems likely that high frequency of A. baumannii infection will be increasing epidemiological importance in the future. However, the current limited understanding of the epidemiology of A. baumannii infections is caused by lack of a rapid and practical method for the molecular characterization of A. baumannii strains. This study was undertaken to determine molecular types and genetic similarity among A. baumannii strains isolated from four hospitals by RAPD analysis. Eighty-five strains, including 40 from Chunnam University Hospital, 27 from Dankook University Hospital, 15 from Yonsei University Hospital, and 3 from Seonam University Hospital, were classified into three molecular types. Molecular type II was the most common pattern and included 72 strains. All strains from Dankook University Hospital and 40 strains from Chunnam University Hospital belonged to molecular type I or II. A. baumannii strains form Yonsei University Hospital were very distant similarity values. The range of genetic similarity values among 85 strains of A. baumannii was 0.26 to 1.00. Although phenotypes including biotype and antimicrobial resistance pattern of A. baumannii strains were same or very similar to each other, their RAPD patterns were quite different. Typing with phenotypes was found to be less reliable than molecular typing by RAPD analysis. These results suggest that RAPD analysis provides rapid and simple typing method of A. baumannii strains for epidemiological studies. This work is the first epidemiological report of A. baumannii infections in Korea and it is hoped that results of this work may contribute to a better understanding of the clinical importance and epidemiology of A. baumannii strains.

• Journal of Veterinary Clinics
• /
• v.32 no.1
• /
• pp.78-84
• /
• 2015

Although researches have highlighted the important role of enhanced farm biosecurity to reduce the severity and prevalence of diseases in livestock, to date there has been little study in Korea on farmers' adoption of biosecurity measures to control porcine reproductive and respiratory syndrome virus (PRRSV) infection. To mitigate the risk of PRRSV infection in pigs, the risk factors by which PRRSV is introduced in pig farms must be determined. The primary aim of this study was to investigate pig producers' perceptions about on-farm biosecurity practices. We also analyzed data obtained from a cross-sectional study on 196 farrow-to-finish farms conducted between March 2013 and February 2014 to identify risk factors for PRRSV infection at farm level. Standardized questionnaires with information about basic demographical data and management practices were collected in each farm by on-site visit of trained veterinarians. Farms were classified as negative or positive through the use of infection profiles that combined data on PCR positive pigs and serological testing including antibody titer, sero-conversion pattern at each age category, and vaccination status. Data on biosecurity practices, farm management and environmental characteristics were analyzed using multivariate ordinal logistic regression. Generally, the biosecurity level in the pig farms included in this study were insufficient to reduce/prevent the risk of PRRSV infection given the high pig density areas and the considerable extent of vehicle movement. Factors associated with PRRSV infection were those where owners used on-farm vaccination programs had a lower risk of infection (OR = 0.19, 95% CI 0.06-0.61). The results from the analysis may guide to tailor biosecurity measures in the reduction or prevention of PRRS to the specific circumstances of pig farms in different localities of the world. To the best knowledge of the authors, this is the first study to report information on the biosecurity practices currently implemented on Korean pig farms.

• Development and Reproduction
• /
• v.21 no.4
• /
• pp.371-378
• /
• 2017

Interferon-stimulated gene 15 (ISG15) is known to interfere with viral replication and infection by limiting the viral infection of cells. Interferon-stimulated gene 15 (ISG15) interferes with viral replication and infectivity by limiting viral infection in cells. It also plays an important role in the immune response. In this study, tissue-specific expression of ISG15 in healthy rock bream samples and spatial and temporal expression analysis of rock bream ISG15 (RbISG15) were performed following rock bream iridovirus (RSIV) infection. RbISG15 expression was significantly higher in the eye, gill, intestine, kidney, liver, muscle, spleen, and stomach, but low in the brain. There were particularly high levels of expression in the liver and muscle. RbISG15 expression was also examined in several tissues and at various times following RSIV infection. ISG15 expression increased within 3 h in the whole body and decreased at 24 h after infection. In addition, temporal expression of several tissues following RSIV infection showed a similar pattern in the muscle, kidney, and spleen, increasing at 3 h and decreasing at 72 h. These results suggest that ISG15 plays an important role in the immune response of rock bream. Overall, this study characterizes the response of RbISG15 following RSIV infection.

• Journal of Preventive Medicine and Public Health
• /
• v.56 no.3
• /
• pp.212-220
• /
• 2023

Objectives: This study compared the epidemiological and clinical manifestations of patients hospitalized with respiratory syncytial virus (RSV) infection before and during the coronavirus disease 2019 (COVID-19) pandemic at a tertiary care hospital in Chiang Mai Province, Thailand. Methods: This retrospective observational study utilized data from all cases of laboratory-confirmed RSV infection at Maharaj Nakorn Chiang Mai Hospital from January 2016 to December 2021. Differences in the clinical presentation of RSV infection before (2016 to 2019) and during (2020 to 2021) the COVID-19 pandemic were analyzed and compared. Results: In total, 358 patients hospitalized with RSV infections were reported from January 2016 to December 2021. During the COVID-19 pandemic, only 74 cases of hospitalized RSV infection were reported. Compared to pre-pandemic levels, the clinical presentations of RSV infection showed statistically significant decreases in fever on admission (p=0.004), productive cough (p=0.004), sputum (p=0.003), nausea (p=0.03), cyanosis (p=0.004), pallor (p<0.001), diarrhea (p<0.001), and chest pain (p<0.001). Furthermore, vigilant measures to prevent the spread of COVID-19, including lockdowns, also interrupted the RSV season in Thailand from 2020 to 2021. Conclusions: The incidence of RSV infection was affected by the COVID-19 pandemic in Chiang Mai Province, Thailand, which also changed the clinical presentation and seasonal pattern of RSV infection in children.

• Korean Journal of Microbiology
• /
• v.46 no.2
• /
• pp.134-139
• /
• 2010

Mycobacterium tuberculosis (Mtb) is one of the most successful pathogens to infect one third of world population. Th1-mediated immunity against Mtb infection is known as critical to express mycobacteriostatic function but it is not sufficient to resolve the infection. In this study, to verify the possibility Mtb itself change the gene expression to survive against host immune response, expression pattern of selected H37Rv genes, 16S rRNA, acr, fbpA, aceA, and ahpC, during the course of infection was measured with absolute quantitation method using real-time RT-PCR. The total number of transcripts of 16S rRNA increased during the course of infection, which was coincide with the increasing CFU. The total number of fbpA transcripts per CFU, which encode typical secreted Mtb antigen, Ag85A, increased for 10 days of infection before decreasing. The number of transcripts of acr per CFU, which encode heat shock protein, ${\alpha}$-crystallin, increased during the infection, and ahpC and aceA, they both are enzymes produced in oxidative stressful condition, increased for 20 days and then slightly decreased on day 30. These findings are one of survival strategy of pathogen evading host immune response lead to persistent infection inside host cells.

• Proceedings of the KIEE Conference
• /
• 1998.07b
• /
• pp.699-702
• /
• 1998

This study investigates the population model of the spread of HIV/AIDS which the infection is generated by an infectious in dividual in a population of susceptibles. A mathematical model is presented for the transmission dynamics of HIV infection within the communities of homosexual males. The pattern on the epidemic character of HIV, the causative agent of AIDS, was analysed by the mathematical model of AIDS system which is derived according to the ecological relationship between five epidemilogic states of individuals. The computer simulation was performed using real data.

• Korean Journal of Veterinary Research
• /
• v.45 no.1
• /
• pp.55-61
• /
• 2005

Serum samples of 1,175 pigs from 148 Korean swine farms not using Mycoplasma hyopneumoniae (M. hyo) vaccines were collected for seroepidemiological study of M. hyo infection by indirect ELISA method. Informations of each farm were provided about province where the farm was located and season when blood samples were collected. Then, the selected farms were divided into farm units which had 5 serum samples according to production stages : sow, suckling piglet (<30 days old), nursery pig (30-70 days old), and growing pig (>70 days old). Seroprevalence of M. hyo infection according to production stages, province, and season was investigated by using ELISA-positve rate of the selected samples for each study. This study showed that 85.34% (78.94-91.78%, 95% CI) of farms were positive to M. hyo infection and 34.81% (32.09-37.53%, 95% CI) among pigs were sero-positive to M. hyo infection in Korean swine farms. In the study of seroprevalence by production stage, most farms had sows and growing pigs which were sero-positive to M. hyo infection (sow: 83.05%, growing pigs: 87.72%) and most pigs seemed to be naturally infected by M. hyo at 8-10 weeks of age. Also, M. hyo infection showed seasonal pattern that most pigs were infected in late fall to early winter. However, in the study of seroprevalence by province, there was no significant correlation between province and M. hyo sero-positive rate.

• Korean Journal of Veterinary Service
• /
• v.22 no.4
• /
• pp.371-375
• /
• 1999

Total 1,434 sera collected from 72 pig farms were tested for the detection of porcine reproductive and respiratory syndrome (PRRS) virus antibodies. The overall seroprevalence of PRRS virus antibodies was 49.3% (707/727). Of 72 farms tested 59 (81.9%) farms had at least one or more than one pigs with PRRS virus antibodies. The seroprevalence of PRRS virus antibody varied with age. Seroprevalence of PRRS virus antibody in 1 to 30-day-old, 31 to 40-day-old, 41 to 50-day-old, 51 to 60-day-old, and over 61-day-old pig were 27.4%, 52.3%, 57.9%, 52.7%, and 68.2%, respectively. Gilt showed relatively higher seroprevalence (61.2%) than sow (29.2%) and boar (38.3%). In most farms, the infection of PRRS virus was chronic and confined to grower or finisher. This pattern of infection suggests that partial depopulation of the infected herds appears be one of the measures to eradicate the PRRS virus infection. High seroprevalence of the PRRS virus antibody in gilts and boars indicates that the infected gilts and boars in the breeding farms are the major source of the PRRS virus infection, and also play an important role in spreading the PRRS virus between fan mates or herds.

• Korean Journal of Veterinary Research
• /
• v.40 no.1
• /
• pp.138-144
• /
• 2000

This study was carried out to investigate the pathogenicity of Korea N caninum isolates, KBA-1 and KBA-2 on SCID mouse following 3 different routes of infection. NC-1 was served as reference isolate. The pathogenecity was evaluated by progression of clinical signs, histopathology and immunohistochemistry. Pathogenicity of KBA-2 appears to be stronger than that of KBA-1 but weaker than that of NC-1. Progress of clinical signs and lesion distribution and pattern of each isolates were similar when the isolates were infected either subcatareously or intraperitoneally. However, oral inoculation of tachyzoites failed to induce the infection.

• Preventive Nutrition and Food Science
• /
• v.10 no.2
• /
• pp.161-166
• /
• 2005

We investigated the effect of pycnogenol (PYC) supplementation on retarding the immune dysfunction of CS7BL/6 mice after murine AIDS (MAIDS) development. Dysfunction of T and B cell mitogenesis from primary cultured splenocytes has been observed with retrovirus infection and PYC supplementation partially recovered the dysfunction of T and B cells. There was an abnormal shift of cytokine pattern with retrovirns infection, which was designated by the decreased secretion of Th1 cytokines and increased secretion of Th2 cytokines. PYC supplementation increased IL-2 and $IFN-\gamma$ secretion and decreased IL-4, IL-6, and $TNF-\alpha$ secretion, but it was not sufficient enough to maintain the normal level of these cytokines. Hepatic vitamin E level was significantly decreased by retrovirns infection, in accordance with increased hepatic lipid peroxidation level, whereas PYC supplementation normalized the hepatic level of vitamin E and lipid peroxidation. This study suggests that PYC supplementation may partially help retard the incidence of symptoms during MAIDS.