Gevers Dirk, Masco Liesbeth, Baert Leen, Huys Geert, Debevere Johan, Swings Jean
Laboratory of Microbiology, Faculty of Sciences, Ghent University, Gent, Belgium.
Syst Appl Microbiol. 2003 Jun;26(2):277-83. doi: 10.1078/072320203322346137.
In order to study the prevalence and diversity of tetracycline resistant lactic acid bacteria (Tc(r) LAB) along the process line of two different fermented dry sausage (FDS) types, samples from the raw meat, the meat batter and the fermented end product were analysed quantitatively and qualitatively by using a culture-dependent approach. Both the diversity of the tet genes and their bacterial hosts in the different stages of FDS production were determined. Quantitative analysis showed that all raw meat components of both FDS types (FDS-01 and FDS-08) contained a subpopulation of Tc(r) LAB, and that for FDS-01 no Tc(r) LAB could be recovered from the samples after fermentation. Qualitative analysis of the Tc(r) LAB subpopulation in FDS-08 included identification and typing of Tc(r) LAB isolates by (GTG)5-PCR fingerprinting, plasmid profiling, protein profiling and a characterization of the resistance by PCR detection of tet genes. Two remarks can be made when the results of this analysis for the different samples are compared. (i) The taxonomic diversity of Tc(r) LAB varies along the process line, with a higher diversity in the raw meat (lactococci, lactobacilli, streptococci, and enterococci), and a decrease after fermentation (only lactobacilli). (ii) Also the genetic diversity of the tet genes varies along the process line. Both tet(M) and tet(S) were found in the raw meat, whereas only tet(M) was found after fermentation. A possible relationship was found between the disappearing of species other than lactobacilli and tet(S), because tet(S) was only found in lacotocci, enterococci, and streptococci. These data suggest that fermented dry sausages are among those food products that can serve as vehicles for Tc(r) LAB and that the raw meat already contains a subpopulation of these bacteria. Whether these results reflect the transfer of resistant bacteria or of bacterial resistance genes from animals to man via the food chain is difficult to ascertain and may require a combination of cultivation-dependent and cultivation-independent approaches.
为了研究两种不同类型发酵干香肠（FDS）生产线上四环素抗性乳酸菌（Tc(r) LAB）的流行情况和多样性，采用基于培养的方法对生肉、肉馅和发酵终产品的样本进行了定量和定性分析。测定了FDS生产不同阶段tet基因及其细菌宿主的多样性。定量分析表明，两种FDS类型（FDS - 01和FDS - 08）的所有生肉成分中都含有Tc(r) LAB亚群，并且对于FDS - 01，发酵后的样本中未检测到Tc(r) LAB。对FDS - 08中Tc(r) LAB亚群的定性分析包括通过(GTG)5 - PCR指纹图谱、质粒图谱分析、蛋白质图谱分析对Tc(r) LAB分离株进行鉴定和分型，以及通过tet基因的PCR检测对抗性进行表征。比较不同样本的分析结果时，可以得出两点结论。（i）Tc(r) LAB的分类多样性在生产线上有所不同，生肉中的多样性更高（包括乳酸乳球菌、乳酸杆菌、链球菌和肠球菌），发酵后多样性降低（仅乳酸杆菌）。（ii）tet基因的遗传多样性在生产线上也有所不同。生肉中同时发现了tet(M)和tet(S)，而发酵后仅发现tet(M)。发现除乳酸杆菌外的其他物种消失与tet(S)之间可能存在关联，因为tet(S)仅在乳酸乳球菌、肠球菌和链球菌中发现。这些数据表明，发酵干香肠是可作为Tc(r) LAB载体的食品之一，并且生肉中已经含有这些细菌的亚群。这些结果是否反映了抗性细菌或细菌抗性基因通过食物链从动物转移到人类，很难确定，可能需要结合基于培养和不依赖培养的方法来进行研究。
