Molecular Diversity of vanA Gene Cluster in Vancomycin-resistant Enterococci Isolated in One University Hospital / 감염과화학요법

BACKGROUND: The vanA gene is the most frequently encountered gene among isolates, causing vancomycin-resistant Enterococci (VRE) infections in humans, and it is part of the transposable element Tn1546. Knowledge of the diversity of Tn1546 is important to distinguish between the dissemination of a single VRE clone and the transmission of a particular Tn1546 type through a genetically divergent population of enterococci. Recently, we studied molecular diversity of Tn1546-related elements in enterococci isolated in one hospital to facilitate understanding of the molecular epidemiology of vancomycin resistance. METHODS: Nineteen VanA-type VRE clinical isolates, collected in one university hospital during 1997 and 1999, were investigated for characteristics such as antibiotic resistance, structure of vanA gene cluster and genomic DNA type by means of antibiotic susceptibility test, PCR amplified length polymorphism of vanA gene cluster and pulse-field gel electrophoresis (PFGE), respectively. RESULTS: Nine (A, B1 to B5, C, D and E) different vanA gene cluster types were identified. Three isolates were grouped into vanA gene cluster type A, similar to that of Tn1546 prototype, and twelve isolates were grouped into type B that has an insertion of IS1216V at vanX-Y intergenic region. Type B was further subdivided into B1 to B5 according to the size variation of vanX-Y intergenic region, which was resulted from the insertion of IS1216V and deletions associated with the insertion. Both vanY and vanZ were deleted in three isolates, suggesting that these genes are not essential for vancomycin resistance. Notably, three E. faecalis and three E. faecium strains isolated during the same period were shown to carry the same vanA gene cluster, showing intergenic transmission of vancomycin resistance. CONCLUSION: The presence of variable types of vanA gene cluster among VRE strains isolated in one hospital suggests that several evolutionary changes of vanA gene clusters have occurred during the horizontal spread of resistance gene in the hospital environment. This approach may be useful for monitoring the evolution of VanA resistance.

Molecular Diversity of vanA Gene Cluster in Vancomycin-resistant Enterococci Isolated in One University Hospital / 감염과화학요법

BACKGROUND: The vanA gene is the most frequently encountered gene among isolates, causing vancomycin-resistant Enterococci (VRE) infections in humans, and it is part of the transposable element Tn1546. Knowledge of the diversity of Tn1546 is important to distinguish between the dissemination of a single VRE clone and the transmission of a particular Tn1546 type through a genetically divergent population of enterococci. Recently, we studied molecular diversity of Tn1546-related elements in enterococci isolated in one hospital to facilitate understanding of the molecular epidemiology of vancomycin resistance. METHODS: Nineteen VanA-type VRE clinical isolates, collected in one university hospital during 1997 and 1999, were investigated for characteristics such as antibiotic resistance, structure of vanA gene cluster and genomic DNA type by means of antibiotic susceptibility test, PCR amplified length polymorphism of vanA gene cluster and pulse-field gel electrophoresis (PFGE), respectively. RESULTS: Nine (A, B1 to B5, C, D and E) different vanA gene cluster types were identified. Three isolates were grouped into vanA gene cluster type A, similar to that of Tn1546 prototype, and twelve isolates were grouped into type B that has an insertion of IS1216V at vanX-Y intergenic region. Type B was further subdivided into B1 to B5 according to the size variation of vanX-Y intergenic region, which was resulted from the insertion of IS1216V and deletions associated with the insertion. Both vanY and vanZ were deleted in three isolates, suggesting that these genes are not essential for vancomycin resistance. Notably, three E. faecalis and three E. faecium strains isolated during the same period were shown to carry the same vanA gene cluster, showing intergenic transmission of vancomycin resistance. CONCLUSION: The presence of variable types of vanA gene cluster among VRE strains isolated in one hospital suggests that several evolutionary changes of vanA gene clusters have occurred during the horizontal spread of resistance gene in the hospital environment. This approach may be useful for monitoring the evolution of VanA resistance.

Expression of the S Genome Segment of Hantaan 76-118 in E. coli: Evaluation of Antigenicity of the capsid Protein

No abstract available.

Partial Sequence Analysis of Puumala Virus M Segment from Bats in Korea

Hantavirus is a genus of the Bunyaviridae family causing two serious diseases, hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). Puumala virus is a member of hantavirus originally found in Europe, and its natural reservoir is Clethrionomys glareolus. It is also associated with the hurnan disease nephropathia epidemica, a milder form of HFRS. To identify the hantaviruses in bats, bats were collected from Jeong-Sun, Won-Joo, Chung-Ju and Hwa-Cheon area in Korea, and nested RT-PCR was performed with serotype specific primer from M segment. Interestingly, Puumala virus was detected in bats (Rhinolophus ferrum-equinum) only from Won-Joo. The 327 bp nested RT-PCR product, was sequenced. The sequence database search indicates that the sequence is homologous to the published sequence of Puumala viruses. The sequence similarities were ranged from 71% to 97%. The highest sequence similarity was 97% with Puumala virus Vranicam strain, and the lowest was 71% with Puumala virus K27 isolate. Puumala virus Vranicam strain was isolated from a bank vole (Clethrionomys glareolus) in Bosnia-Hercegovina. Puumala virus K27 was isolated from human in Russia. This analysis confirms that bats (Rhinolophus ferrum-equinum) in Korea are natural reservoir of Puumala virus.

Study of Exoparasites, Rickettsia and Hantaan virus in Bats

To study the relation between ectoparasite, Rickettsia and hantaan virus in bats, four order of Athropoda were collected from Rhinolophus ferrumequinum captured in Cheju and Eptesicus serotinus captured in Chungnamin from July 1989 to March 1998. Also antibody of Rickettsia and hantaan virus were detected by immunofluoroscent antibody technique and RT-PCR. The results are as follows. 1. Five species of Acarina were identified from E. serotinus: Leptotrobidium subakamushi of Trombiculidae, Macronyssus coreanus, Steatonyssuss spinosuss and Steatonychus superans of Macronyssidae, Argas vespertilionis of Metastigmata. 2. Ischnopsyllus needhami of Siphonaptera and Cimex of Hemiptera were identified from E. serotinus. 3. Cyteribia uenoi and Brachytarsina kanoi of Diptera were identified from R. ferrumequinum. 4. The positive rate of rickettsial antibodies in E. serotinus were 17.58%, 15.15%, 22.22%, 52.73% against R. tsutsugamushi, R. typhi, R. sibirica and R. thai tick typhus, respectively. The high positive rate of antibody related to the high content of Arthropoda. 5. The Positive rate of hantaan virus IFA antibodies were 3.4% (27 of 802) and hanntan virus infection rate 36.7% (22 of 60) by RT-PCR in bats. According these result, we showed that certain species of Athropoda isolated play a role as vector of Rickettsia in E. serotinus. Also bats play a role as a reservoir of hantaan virus in nature.

Detection of Puumala and Hantaan Viruses among Bats in Korea by Nested RT-PCR

Hantavirus is a genus of the Bunyaviridae family consisting following serotype groups: Hantaan, Seoul, Puumala, Prospect Hill, Thailand, Belgrade, Thotta palayam, Sin Hombre. Most of Hantavirus group have been associated with many clinically similar disease known collectively as hemorrhagic fever with renal syndrome (HFRS). Hantaan virus is the prototype of the genus hantavirus, originally isolated from Apodemus agrarius. Bat was found as a natural host for Hantaan virus in Lee's lab for the first time. Then, Hantaan-like virus was isolated Hantaan-like virus from bat. To identify hantaviruses that are present in Korea among bats, bats were collected from Jeong-Sun, Won-Joo, Chung-Ju and Hwa-Cheon area, RNA was isolated from lung and serum. RT-PCR was performed with a universal primer from M segment. Nested RT-PCR was carried out to differentiate Hantaan, Seoul and Puumala virus using serotype specific primers. As we expected, Hantaan viruses were detected in bats and Seoul virus was not detected. Interestingly, Puumala viruses were also detected in bats from won-Ju, but not in other areas. Puumala virus is originally isolated from Clethrinomys glareolus, and cause light HFRS. Recently, Paradoxomis webbiana, a wild bird turn out to be a reservoir for Puumala virus in Korea. These data indicate that bat is a new natural reservoir of Puumala virus.