At LNSP, the outbreak isolates were identified as V. cholerae
[serogroup] O1, [serotype] Ogawa, and selected specimens were
sent to CDC for confirmation and additional analyses. As of
November 13, CDC had isolated V. cholerae from 14 specimens
received from LNSP. All isolates were identified phenotypically
and characterized by serotyping, biotyping, antimicrobial
susceptibility testing, and by pulsed-field gel electrophoresis
(PFGE), performed using a protocol developed by PulseNet
International, the international molecular subtyping network for
foodborne and waterborne disease surveillance. Additionally, the
isolates were characterized genetically for the presence and
subtype of certain virulence factors (e.g., the cholera toxin,
genes specific for strains associated with the ongoing cholera
pandemic, and antimicrobial resistance genes). The 14 isolates
associated with the outbreak in Haiti were indistinguishable by
all laboratory methods, revealing that the outbreak strain was
V. cholerae serogroup O1, sero