Characteristics of a pandemic clone of O3:K6 and O4:K68 Vibrio parahaemolyticus isolated in Beira, Mozambique

The genetic characteristics of Vibrio parahaemolyticus strains isolated in 2004 and 2005 in Mozambique were assessed in this study to determine whether the pandemic clone of V. parahaemolyticus O3:K6 and O4:K68 serotypes has spread to Mozambique. Fifty-eight V. parahaemolyticus strains isolated from hospitalized diarrhoea patients in Beira, Mozambique, were serotyped for O:K antigens and genotyped for toxR, tdh and trh genes. A group-specific PCR, a PCR that detects the presence of ORF8 of the filamentous phage f237, arbitrarily primed PCR, PFGE and multilocus sequence typing were performed to determine the pandemic status of the strains and their ancestry. All strains of serovars O3:K6 (n=38) and O4:K68 (n=4) were identified as a pandemic clonal group by these analyses. These strains are closely related to the pandemic reference strains of O3:K6 and O4:K68, which emerged in Asia in 1996 and were later found globally. The pandemic serotypes O3:K6 and O4:K68 including reference strains grouped into a single cluster indicating emergence from a common ancestor. The O3:K58 (n=8), O4:K13 (n=6), O3:KUT (n=1) and O8:K41 (n=1) strains showed unique characteristics different from the pandemic clone.