Detection and drug resistance of Laribacter hongkongensis isolated from freshwater products and reservoir water in Guangzhou city

Objective To examine Laribacter hongkongensis(LH) contamination of freshwater products and reservoir water in Guangzhou city,and to assess drug resistance of LH isolated.Methods A total of 324 freshwater product samples from 4 farmers' markets and 6 surface water samples from 6 reservoirs were collected from December 2013 to May 2014.All the samples were plated onto cefoperazone MacConkey agar and incubated under aerobic condition at 37 ℃ for 48 hours.All suspected isolates were identied phenotypically with standard conventional biochemical methods.Isolates suspected to be LH were subjected to 16S rRNA gene sequencing.Results The overall detection rate of LH was 16.36%(53/324) for freshwater products,with the rates of 17.97%(46/256) for grass carps and 46.67%(7/15) for tiger frogs; but for 53 samples of Cipangopaludina cahayensis no LH strain was isolated.LH was isolated from Helong reservoir among six detected reservoirs.The genetic homology of the isolated LH strains with the standard strain(HKU1) was 98%-99%.The rate of drug resistance of the isolated LH strains to first-generation cephalosporins and third-generation cephalosporins were 94.44% -98.15%,and 70.37% to rifampicin.Conclusion There are contaminations of LH in freshwater products and reservoir water in Guangzhou city and the LH strains are highly resistant to cephalosporin and rifampicin.