Occurrence of pathogenic and spoilage bacteria in salmon sashimi: Histamine and antimicrobial susceptibility evaluation

Abstract

The study of the hygienic sanitary conditions of raw consumed meat foods, such the sashimi, is necessary to define their quality and possible health consequences for the population. Sixty samples of salmon sashimi (Salmo salar) were collected from ten restaurants in the city of São Luís, Maranhão, Brazil, six from each site. The samples were analyzed for coliform counts at 35 °C, coliforms at 45 °C and positive and negative coagulase Staphylococcus, presence of Escherichia coli, Salmonella sp., Vibrio parahaemolyticus and Aeromonas spp, antimicrobial susceptibility test of the isolates and quantification of histamine in the samples. The results showed high counts of coliforms at 35 °C and 12 samples with >102 NMP/g of coliforms at 45 °C, presence of E. coli and Salmonella in 3 samples each, absence of V. parahaemolyticus and coagulase positive Staphylococcus and coagulase negative Staphylococcus count between <20 and 5.0x104 CFU/g, presence of Aeromonas in 95% of the samples, 60 isolates being A. hydrophila and 6 A. caviae. For susceptibility to antimicrobials, E. coli isolates were sensitive to CPM, CTX, LVX, PPT and SUT, two isolates were resistant to AMP; one resistant to GEN, one to AMI and one to AMC. Salmonella isolates were sensitive to AMC, CPM, CFO, CRX, GEN, LVX and PPT, one resistant to AMI and one to AMP and SUT. The isolates of Aeromonas were resistant on mean to five of the antimicrobials, with AMP (97%), CRX (90.9%) and AMC (77.3%), and 81.8% were sensitive to CPM. Histamine levels ranged from 44.06 ± 0.74 to 505.46 ± 8.83 mg/kg, 21 of the samples with levels higher than 100 mg/kg. The samples presented unsatisfactory sanitary hygiene conditions and public health risks, due to the detection of pathogenic bacteria and high concentrations of histamine capable of causing scombroid poisoning, and isolates show multiresistance to the tested antimicrobials.