Genotypic and Phenotypic Characterization of Enteropathogenic Escherichia coli Isolated from Diarrheal Patients in Gwangju

Enteropathogenic Escherichia coli (EPEC) have been implicated in human diarrhea in several countries. Central to EPEC-mediated disease is its ability to cause intestinal lesions, known as attaching and effacing (A/E) lesion. We investigated 92 EPEC strains isolated from patients with diarrhea in Gwangju for their genotypic and phenotypic characteristics. Sixteen (17.4%) of all strains were found to be typical EPEC because they were bfpA gene positive by PCR. The most of typical EPEC isolates (87.5%) showed a localized adhesion (LA) pattern in Hep-2 cell adherence assay, whereas, only 11 atypical EPEC isolates (14.5%) were adhered to Hep-2 cells in a localized manner. Thirteen of the EPEC strains studied belonged to classical O-serogroups of EPEC and 7 isolates were classified as nonclassical EPEC serogroup and the other isolates could not be serotyped with our antisera. The subtypes of eae, tir, espA and espB genes which are major virulence genes concerned of A/E lesion on chromosome were analyzed by multiplex PCR for finding the original resource. The results showed that the composition of these genes subtypes was homogenous and heterogenous in 12 and 26 isolates, respectively. The others were non-determined type in terms of the gene subtype because of genetic diversity of intimin-coding eae genes. Our findings indicated that EPEC isolates from patients with diarrhea were diverse genetically and phenotypically, which require further study in regard to their virulence and epidemiological significance.

Epidemiological Study of Viral Diarrhea in Gwangju Area During 2000~2002

There are well known infectious diarrheal disease including viral disease such as HuCVs (Human caliciviruses), rotaviruses, enteric adenoviruses and astroviruses. We performed surveillance of infectious diarrheal disease in this study for providing the information for regional prevalence of infectious diarrheal disease and establish basement of diagnostic scheme for these infectious diarrheal disease. For the study, 3,400 stool specimens collected from 10 hospitals in Gwangju from April 2000 to March 2002 were used in investigation for the detection of infectious diarrheal disease. For group A rotaviruses, enteric adenoviruses and astrovirus, we carried out antigen capturing ELISA and RT-PCR with specific primers reacting RNA dependent RNA polymerase gene of HuCVs is used for the detection of RNA of HuCVs. As a results, we detected viral antigen or genome from 537 out of 3,400 specimens (15.8%). 443 out of 537 (82.5%) were confirmed as rotaviruses antigen positively, and 14 (2.6%) and 3 (0.8%) samples were antigen positive to enteric adenoviruses and astroviruses, respectively. We detected HuCV genome from 73 (13.6%) samples by specific amplification. We found that predominantly causative virus is rotavirus in Gwangju but HuCVs take major portion of viral agents causing diarrhea considering the age and seasonal distribution of specimens. Prevalence of adenoviruses and astroviruses are very low compared with worldwide situation. While the infection of rotavirus is limited to young infant under 2 years old, infection of HuCV has wide age distribution. These results suggest that existence of various strains of HuCVs and low rate of cross-protection among distinct antigenic group make it difficult to form immunity in older age. This epidemiological information relating to various diarrheic viruses is first reported in Gwangju, therefore it could provide present prevalence of viral agents causing gastroenteritis and backgrounds to establishment of protection viral diarrhea and development.

Clinico-epidemiologic and Virologic Study of Measles Outbreak in Gwangju Metropolitan City During the 2000~2001 Epidemic / 감염

BACKGROUND: Measles is a highly contagious disease caused by measles virus. Although the introduction of live attenuated measles vaccines has dramatically abrogated the endemic incidence of measles in world-wide, there are still 30 million measles cases and nearly one million deaths from measles annually. In this study, we characterized the measles outbreak in Gwangju Metropolitan City during the 2000~200 1 epidemic. METHODS: Study population included measles patients in Gwangju Metropolitan City from April, 2000 to May, 200 1. We conducted a questionnaire survey on the patients and analyzed the records based on the clinical guideline of World Health Organization (WHO). Furthermore, we isolated the measles viruses from clinical specimens of patients and analyzed the nucleotide sequences of nucleoprotein (N) gene. RESULTS: During the April 2000 to May 2001, measles epidemic, a total of 3,2 17 measles patients were reported in Gwangju Metropolitan City. The first patient of measles was reported on April, 2000. The incidence reached its peak in November, 2000 and decreased thereafter. The age distribution of the patients were various, which was ranged from 1 month after birth to 30 year adult and the peak incidence was observed at 7~13 year old. Various complications were developed in 232 patients and 2 of them died. Phylogenetic analyses of nucleotide sequences and deduced amino acid sequences of the N genes of isolated viruses revealed that all viruses isolated in Gwangju Metropolitan City were grouped into the clade H1. This suggests that a single, predominant viral genotype was responsible for the measles epidemic in Gwangju Metropolitan City. CONCLUSION: In this study, we characterized the measles outbreak in Gwangju Metropolitan City during 2000~200 1. The measles outbreak in Gwangju Metropolitan City was considered to be caused by single genotype of measles virus (clade H1). After a massive vaccination campaign among 7~16 years old children to eliminate indigenous measles from this country, it is important to continue measles vaccination and intensive surveillance clinically as well as virologically.