Forty-three clinical strains of V. cholerae O1 biotype El Tor were isolated between 3 May and
10 June 1998 during an outbreak in the metropolitan area of Kuala Lumpur and its suburbs.
With the exception of three Inaba strains that were restricted to three members of a family, all
the others belonged to the Ogawa serotype. The strains were analysed for clonality using
ribotyping and pulsed-field gel electrophoresis (PFGE). Two ribotypes, V/B21a and B27, were
identified among 40 Ogawa isolates using BglI restriction endonuclease. Ribotype V/B21a has
been described previously from Taiwan and Colombia and several Asian countries while B27
has been reported among isolates from Senegal. The three Inaba strains belonged to one
ribotype, designated type A, not previously reported. PFGE analysis using NotI revealed that
all isolates within a ribotype had identical profiles demonstrating clonality amongst the strains.
Dice coefficient analysis of the two Ogawa genotypes revealed 89% similarity on ribotype
patterns and 91.3% on PFGE profiles. Ribotype V/B21a isolates were associated with cases
from dispersed areas of Kuala Lumpur and its suburbs while ribotype B27 was restricted to
cases from one particular area suggesting a common-source outbreak.