Masahiko Ehara1, Nguyen Binh Minh2, Tran Huy Hoang2, Nguyen Dong Tu2,
Nguyen Thi Phuong Lan3, Tran Thi My Trinh3,
and Masaaki Iwanaga4
1 Department of Bacteriology,
2 Department of Bacteriology, National
Institute of Hygiene and Epidemiology,
3 Department of
Microbiology and Immunology, Pasteur Institute of
4 Department of
Bacteriology, Faculty of Medicine, University of the Ryukyus,
Background: Since
the outbreak of Vibrio cholerae O139 in late 1991, the presence of multidrug
resistance genes (SXT elements) have been known to exist widely among Gram
negative rods. Although many strains of Vibrio
cholerae O1were known resistant to tetracycline and ST compound, the
mechanism is not clearly known.
Objective: The presence of multi-drugs resistance
genes was analyzed by Polymerase Chain Reaction (PCR). Each resistance gene was
sequenced to know the clonality of outbreak strains in Southeast Asian
countries.
Methodology: Vibrio strains were cultured on BTB agar
plates at 37° overnight and
small aliquot was suspended in 100 microliter of 1% NP-40 (Suspemsion buffer).
These suspensions were heated at 94° for 10 min and used as DNA templates. PCR
was carried out using AccuPower PCR Premix (BIONEER). DNA sequencing was done
by ABI310 automated sequencer (Perkin Elmer, Applied Biosystem).
Results: Strains isolated in 2000 were shown to
share a common SXT element independent of countries where strains were
isolated. This SXT element was very unique to have the remnant of organic
mercury resistance gene(merR) together with tetA gene.
Conclusion: The presence of SXT element in the 2000 – isolates
strongly suggests the clonality of outbreak strains, although the source still
remains unclear.
Acknowledgements: The financial support of the Japan Society
for the Promotion of Science(JSPS) is acknowledged.
Keywords: Vibrio
cholerae O1, SXT element,
Clonality of outbreak strains