Laconcha I, López-Molina N, Rementeria A, Audicana A, Perales I, Garaizar J
Department of Immunology, Microbiology and Parasitology, Basque Country University, Victoria-Gasteiz, Spain.
Int J Food Microbiol. 1998 Mar 3;40(1-2):27-34. doi: 10.1016/s0168-1605(98)00007-5.
Phage typing (PT) combined with pulsed-field gel electrophoresis (PFGE) and a random amplified polymorphic DNA (RAPD) fingerprinting method was used to characterize Salmonella enteritidis strains. Twenty-four epidemiologically unrelated isolates, sampled from diverse ecological niches and fifteen isolates from four well-defined outbreaks of foodborne gastroenteritis, were studied. Seven phage types, with a predominance of PT 4 (63% of isolates), were observed when analysing the epidemiologically unrelated group. PT 4 was detected in all of the ecological niches studied, including food and fecally polluted river and beach water. The discriminatory power for phage typing, the average probability that the typing system will assign a different type to two unrelated strains randomly sampled in the microbial population, was 0.62. Ten PFGE pattern types were obtained with Xba I restriction endonuclease enzyme among the unrelated isolates; thirteen isolates belonged to PFGE pattern type 1 and the rest of the PFGE types were assigned to one or two isolates. The Dice coefficient clustered the similarities of the PFGE patterns between 80-100%. PFGE showed a discriminatory power of 0.72. Five clearly distinct RAPD patterns were observed with the OPS-19 oligonucleotide, but the discrimination obtained was low (0.46). The combination of the three typing methods increased the number of types to seventeen, giving high discrimination (0.92). Seven of the isolates recovered from various ecological niches belonged to the combination PT 4/PFGE 1/RAPD A and other combinations were unique or included only two strains. The four epidemiologically well-defined foodborne outbreaks were associated with the PT 4 phage type. In two of the outbreaks, other phage types (PT 7a and RDNC) were also observed in two isolates. Most of the isolates belonging to the foodborne outbreaks had an identical PFGE pattern (PFGE pattern type 1), but a difference in a restriction band was observed in an isolate belonging to an outbreak. Two RAPD patterns were observed in the outbreaks; RAPD pattern type A was detected in three of the four outbreaks. When the combined typing method was applied to the study, high concordance was observed and most of the outbreak strains belonged to the combination PT 4/PFGE 1/RAPD A. It is concluded that the combination of phage type with PFGE and RAPD provides a powerful discriminatory tool for the epidemiological analysis of unrelated and related strains of S. enteritidis.
采用噬菌体分型（PT）结合脉冲场凝胶电泳（PFGE）以及随机扩增多态性DNA（RAPD）指纹图谱法对肠炎沙门氏菌菌株进行特征分析。研究了从不同生态位采集的24株流行病学上无关联的分离株，以及从4起明确的食源性肠胃炎暴发中分离出的15株菌株。在分析流行病学无关联组时，观察到7种噬菌体类型，其中PT 4占主导（63%的分离株）。在所有研究的生态位中均检测到PT 4，包括食品以及受粪便污染的河流和滩涂水。噬菌体分型的鉴别力，即分型系统将不同类型随机分配给微生物群体中两个无关联菌株的平均概率为0.62。在无关联的分离株中，用Xba I限制性内切酶获得了10种PFGE图谱类型；13株分离株属于PFGE图谱类型1，其余的PFGE类型各分配给1株或2株分离株。Dice系数将PFGE图谱的相似度聚类在80% - 100%之间。PFGE显示出的鉴别力为0.72。用OPS - 19寡核苷酸观察到5种明显不同的RAPD图谱，但获得的鉴别力较低（0.46）。三种分型方法的组合使类型数量增加到17种，鉴别力较高（0.92）。从不同生态位分离出的7株菌株属于PT 4/PFGE 1/RAPD A组合，其他组合是独特的或仅包含2株菌株。4起流行病学明确的食源性暴发与PT 4噬菌体类型相关。在其中两起暴发中，在2株分离株中还观察到其他噬菌体类型（PT 7a和RDNC）。大多数属于食源性暴发的分离株具有相同的PFGE图谱（PFGE图谱类型1），但在一株属于暴发的分离株中观察到一条限制性条带存在差异。在暴发中观察到2种RAPD图谱；在4起暴发中的3起检测到RAPD图谱类型A。当将组合分型方法应用于该研究时，观察到高度一致性，并且大多数暴发菌株属于PT 4/PFGE 1/RAPD A组合。结论是，噬菌体分型与PFGE和RAPD的组合为肠炎沙门氏菌无关联和相关菌株的流行病学分析提供了一种强大的鉴别工具。
