Presence, Growth and Survival of Yersinia enterocolitica in Oysters, Shrimp and Crab

Abstract

Yersinia enterocolitica was recovered from 6 of 45 (13%) oyster, 2 of 50 (4%) shrimp and 12 of 58 (21%) blue crab samples. No single method of enrichment (cold mannitol broth or modified Rappaport broth for 7, 21 or 60 days) was most effective for the three types of shellfish examined. The effect of refrigerated storage on Y. enterocolitica depended upon the type of shellfish, condition (raw or boiled), strain of Y. enterocolitica and temperature and time of storage. In general, Y. enterocolitica counts increased in (a) raw oysters stored at 0–2 C for 14–21 days and at 5–7 C for 2–10 days, (b) in boiled shrimp stored at 3–5 C for 7–21 days and (c) in cooked crab meat stored at 5 C for 14 days. Freezing and heating of shrimp and crab meat caused extensive destruction of Y. enterocolitica. Biotypes capable of causing human illness (when inoculated into seafoods) survived and under certain conditions multiplied at refrigeration temperatures. Biochemical characteristics of the isolates from raw shellfish differed from those of clinically significant types.