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.

摘要 供直接生食的肉类食品（如生鱼片sashimi）的卫生安全状况研究，对于明确其品质及对人群可能产生的健康影响具有重要意义。本研究从巴西马拉尼昂州圣路易斯市的10家餐饮场所各采集6份大西洋鲑（Salmo salar）生鱼片样本，共计60份。对所有样本开展了以下检测：35℃与45℃环境下的大肠菌群计数、凝固酶阳性葡萄球菌与凝固酶阴性葡萄球菌检测、大肠埃希氏菌（Escherichia coli）、沙门氏菌属（Salmonella sp.）、副溶血性弧菌（Vibrio parahaemolyticus）及气单胞菌属（Aeromonas spp.）的检出鉴定、分离株的抗菌药物敏感性试验，以及样本中组胺的定量检测。
检测结果显示，35℃环境下大肠菌群计数超标，且有12份样本的45℃大肠菌群数超过102最可能数/克（NMP/g）；3份样本检出大肠埃希氏菌，另有3份样本检出沙门氏菌属；未检出副溶血性弧菌与凝固酶阳性葡萄球菌；凝固酶阴性葡萄球菌计数介于<20至5.0×10^4菌落形成单位/克（CFU/g）之间；95%的样本检出气单胞菌属，其中60株为嗜水气单胞菌（A. hydrophila）、6株为豚鼠气单胞菌（A. caviae）。
在抗菌药物敏感性方面，大肠埃希氏菌分离株对头孢哌酮（CPM）、头孢噻肟（CTX）、左氧氟沙星（LVX）、哌拉西林他唑巴坦（PPT）以及磺胺甲恶唑甲氧苄啶（SUT）敏感；2株对氨苄西林（AMP）耐药，1株对庆大霉素（GEN）耐药，1株对阿米卡星（AMI）耐药，1株对阿莫西林克拉维酸钾（AMC）耐药。沙门氏菌属分离株对阿莫西林克拉维酸钾（AMC）、头孢哌酮（CPM）、头孢呋辛（CFO）、头孢曲松（CRX）、庆大霉素（GEN）、左氧氟沙星（LVX）及哌拉西林他唑巴坦（PPT）敏感；1株对阿米卡星（AMI）耐药，另有1株对氨苄西林（AMP）与磺胺甲恶唑甲氧苄啶（SUT）耐药。
气单胞菌属分离株平均对5种受试抗菌药物呈现耐药性，其中对氨苄西林（AMP）、头孢曲松（CRX）与阿莫西林克拉维酸钾（AMC）的耐药率分别为97%、90.9%与77.3%，另有81.8%的分离株对头孢哌酮（CPM）敏感。
样本中组胺含量范围为44.06±0.74 mg/kg至505.46±8.83 mg/kg，其中21份样本的组胺含量超过100 mg/kg。本次采集的三文鱼生鱼片样本卫生状况不合格，且存在公共健康风险：检出致病菌与高浓度组胺（可引发鲭鱼毒素中毒），且分离株对受试抗菌药物呈现多重耐药性。