[Virulent gene prevalence of foodborne Listeria monocytogenes in China in 2005].

OBJECTIVE

To study the virulent gene prevalence of foodborne Listeria monocytogenes (LM) isolated from China.

METHODS

78 LM isolates derived from raw meat, cooked food, aquatic products and vegetables of 13 provinces and cities.LM isolates were investigated for prevalence of virulence genes (LIPI-1 (prfA, plcA, hly, mpl, actA, plcB); LIPI-2 (inlA, inlB), and iap) by PCR method.

RESULTS

87.2% (68/78) of the isolates were prfA positive, 98.7% (77/78) of the isolates were plcA, actA and plcB positive, 97.4% (76/78) of the isolates were hly positive, 87.2% (68/78) of the isolates were mpl positive, 92.3% (72/78) of the isolates were inlA positive, 100% (78/78) of the isolates were inlB positive, 98.7% (77/78) of the isolates were iap positive. Among 21 virulent gene negative isolates, there was 7 isolates lack of two or more virulence genes. The rate of virulence genes deletion isolates from cooked meat was 31.3% (10/32), the rate of virulence genes deletion isolates from raw meat was 16.1% (5/31), the rate of virulence genes deletion isolates from vegetables was 36.4% (4/11) and rate of virulence genes deletion isolates from seafood was 50% (2/4). No significant difference was found (χ(2) = 3.721, P > 0.05). The virulence gene array-1 strains were dominant among these isolates.

CONCLUSION

Among 78 LM isolates, prevalent of virulent genes were different except inlB, virulence genes of LIP-1 were deleted prevalently among isolates, virulence gene deletion patterns were diverse.