Detection of viable and viable nonculturable Vibrio cholerae O1 through cultures and immunofluorescence in the Tucumán rivers, Argentina.

Vibrio cholerae has been sporadically isolated from rivers in Tucuman, Argentina, since the outbreak in 1991. The aim of this study was to determine the environmental reservoir of the bacterium in these rivers, assessing the presence of Vibrio cholerae non-01 and 01 (the latter both in its viable culturable and non culturable state) and its relationship to enviroizmeiitalpb) sicocheinicaI variables. 18 water samplings were collected in the SaliRiver (in Canal Norte and Banda) and the Lules River between 2003 and 2005. physical-chemical measurements (PH, water temperature, electrical conductivity and dissolved oxygen) were examined. Vibrio cholerae was investigated with conventional culture methods and with Direct Innnunofluorescence (DFA-VNC) in order to detect viable non culturable organisms. All isolated microorgam. sins corresponded to Vibrio cholerae non-01 and non-0139 (Lules 26%, Canal Norte 33% and Banda 41%). The majority was found during spring and summer and correlated with temperature and pH. Alon culturable Vibrio cholerae 01 was detected year round in 38 of the 54 water samples analYzed. Application of the Pearson correlation coefficient revealed that there was no relationship between positive innnunofluorescence results and environmental phscicochemical parameters. Genes codingfor somatic antigen 01 were confirmed in a11DEA- VAIC-positive samlilts, whereas the virulence-associated co,4 and tcpA genes were cotormed in 24 samples.