Martínez O, Rodríguez-Calleja J M, Santos J A, Otero A, García-López M L
Department of Food Hygiene and Food Technology, University of León, E-24071-León, Spain.
J Food Prot. 2009 Jul;72(7):1443-9. doi: 10.4315/0362-028x-72.7.1443.
Galicia's coast (northwestern Spain) is a major producer of bivalve molluscs. Over an 18-month period, the presence of Salmonella, Aeromonas, Plesiomonas shigelloides, Vibrio parahaemolyticus, and Clostridium botulinum was determined by PCR methods in mussels (22 batches) and infaunal bivalves (31 batches of clams and cockles) before and after depuration. All batches were harvested from Galician class B harvesting areas where bivalve molluscs must not exceed 4,600 Escherichia coli per 100 g of flesh and liquor in 90% of the samples. Virulence-associated genes of Salmonella (invA), Aeromonas (aerA, hlyA, alt, ast, and laf), P. shigelloides (hugA), V. parahaemolyticus (tdh and trh), and C. botulinum (BoNT) were not detected. The pR72H chromosomal DNA fragment, which is conservative in V. parahaemolyticus strains, was detected in five (4.7%) samples. A number of 192 suspect isolates did not fit the description of clinical Aeromonas phenospecies, pathogenic Vibrio spp., or P. shigelloides. The effectiveness of commercial depuration in reducing bacterial indicators was also examined. E. coli was reduced to < or = 230/100 g of flesh and liquor in 90.9% of mussel lots but in only 70.9% of infaunal bivalve lots. For total coliform elimination, mussels were also more effective. Total counts significantly (P < 0.005) correlated with numbers of Pseudomonas, Aeromonas, and Vibrio. Our data indicate that Salmonella and pathogenic bacteria indigenous to estuarine environments do not appear to be significant hazards in Galician molluscan shellfish. A reason for concern, however, is that clearance of E. coli to acceptable levels was not always achieved especially in infaunal bivalves.
加利西亚海岸（西班牙西北部）是双壳贝类的主要产地。在18个月的时间里，通过聚合酶链式反应（PCR）方法，对净化前后的贻贝（22批）和穴居双壳贝类（31批蛤和鸟蛤）中的沙门氏菌、气单胞菌、类志贺邻单胞菌、副溶血性弧菌和肉毒梭菌的存在情况进行了测定。所有批次均采自加利西亚B级捕捞区，在这些区域，双壳贝类每100克肉和体液中的大肠杆菌数量在90%的样本中不得超过4600个。未检测到沙门氏菌（invA）、气单胞菌（aerA、hlyA、alt、ast和laf）、类志贺邻单胞菌（hugA）、副溶血性弧菌（tdh和trh）和肉毒梭菌（肉毒毒素）的毒力相关基因。在五个（4.7%）样本中检测到了副溶血性弧菌菌株中保守的pR72H染色体DNA片段。192株可疑分离株不符合临床气单胞菌表型种、致病性弧菌属或类志贺邻单胞菌的描述。还检查了商业净化在降低细菌指标方面的有效性。在90.9%的贻贝批次中，大肠杆菌减少至≤230/100克肉和体液，但在穴居双壳贝类批次中仅为70.9%。对于总大肠菌群的消除，贻贝也更有效。总数与假单胞菌、气单胞菌和弧菌的数量显著相关（P<0.005）。我们的数据表明，河口环境中的沙门氏菌和致病菌在加利西亚贝类中似乎不是重大危害。然而，一个令人担忧的原因是，大肠杆菌清除到可接受水平的情况并非总能实现，尤其是在穴居双壳贝类中。
