多重与单一耐药的副溶血性弧菌在纯培养及南美白对虾中生长动力学的参数比较研究

Growth Kinetic Parameters of Multi-drug and Single-drug Resistant Vibrio parahaemolyticus Strains in Pure Culture and in Penaeus vannamei

为比较多重与单一耐药的副溶血性弧菌生长动力学差异,并探索"细菌耐药性"与"风险"之间的关联,本研究应用Bioscreen全自动微生物生长曲线分析仪结合梯度稀释法,对不同耐药程度的副溶血性弧菌在纯培养条件(TSB)下的最大比生长速率(μmax)进行了比较分析。进一步选取六重耐药的VPD18菌株与单一耐药的VPD43菌株接种于南美白对虾中,构建不同温度下的生长曲线,采用Baranyi模型进行拟合得出生长动力学参数。结果显示:在纯培养条件下,多重与单一耐药的副溶血性弧菌的μmax间并无显著性差异(P>0.05)。而在南美白对虾中,单一耐药的副溶血性弧菌的μmax更大,但六重耐药的菌株却具有更短的延滞期(λ)。基于该现象提出假设:细菌耐药程度的增加可能导致其延滞期缩短,但对其最大比生长速率影响不显著。该结果可为我国开展副溶血性弧菌的定量风险评估提供基础数据。

The variations in growth kinetic parameters of single- and multi-drug resistant Vibrio parahaemolyticus strains were investigated, and the relationship between bacterial resistance and risk was explored. A Bioscreen-C automated growth curve analysis system combined with the serial dilution method was employed to compare and analyze the maximum specific growth rates(μmax) of V. parahaemolyticus strains with varying degrees of drug resistance cultured in trypticase soy broth(TSB). Furthermore, Penaeus vannamei was inoculated with the VPD18 strain, which is resistant to six antibiotics, and the VPD43 strain, which is only resistant to ampicillin. Growth curves at different temperatures were established and then the growth dynamics parameters were calculated using the Baranyi model. There was no significant difference in μmax values between the single- and multi-drug resistant strains grown in TSB(P > 0.05). However, in P. vannamei, the μmax of the single-drug resistant strain was higher than that of the strain resistant to six antibiotics, but the latter strain had a shorter lag time(λ). These results suggest that the increase of antibiotic resistance may lead to a shortened λ, but has no significant effect on the μmax. The results of this study can provide basic data for the development of a quantitative risk assessment of V. parahaemolyticus in China.