Faruque S M, Roy S K, Alim A R, Siddique A K, Albert M J
Molecular Biology Laboratory, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
J Clin Microbiol. 1995 Nov;33(11):2833-8. doi: 10.1128/jcm.33.11.2833-2838.1995.
Cholera is endemic in Bangladesh, and a regular seasonal pattern of cholera epidemics occurs. We examined the clonal relationships among 103 clinical and environmental Vibrio cholerae isolates belonging to O1, O139, or non-O1 non-O139 serogroups isolated during epidemic and interepidemic periods in Bangladesh and compared them with those of 51 V. cholerae isolates from four countries in Asia and Africa. These studies were done by a computer-assisted numerical analysis of the restriction endonuclease cleavage patterns of rRNA genes (ribotypes). Unweighed pair-group cluster analysis of BglI- and HindIII-generated band patterns revealed 16 clusters. Ribotypes were defined as clusters of strains possessing > 98% similarity. The results showed that 154 isolates could be differentiated into 15 different ribotypes, and strains belonging to 3 of these ribotypes (ribotypes I, V, and VIIIA and VIIIB) were isolated more frequently during the epidemic periods than during interepidemic periods in Bangladesh. Classical vibrios belonged to six different ribotypes (ribotypes I to VI), with a mean similarity coefficient of 0.84, and the El Tor vibrios belonged to five different ribotypes (ribotypes VIIIA and IX to XII), with a mean similarity coefficient of 0.82. A single clone of El Tor vibrios (ribotype XII) was resident in Tanzania, whereas Nigeria, Syria, and India shared toxigenic El Tor strains with Bangladesh. Cholera toxin (CT)-positive O139 vibrios isolated from Bangladesh and India belonged to a single ribotype (ribotype VIIIB) and were > 98% similar to one of the ribotypes of El Tor vibrios (ribotype VIIIA), but a CT-negative O139 vibrio from Argentina (ribotype XIII) was < 75% similar to the same cluster of El Tor vibrios, thus suggesting more than one possible origin for O139 vibrios. Strains belonging to the same ribotypes (ribotypes VIII to X) were isolated from both patients and surface water in Bangladesh, indicating possible transmission through surface water. A clone of a CT-positive environmental isolate of non-O1 V. cholerae (ribotype VII) was found to be closely related (76.3% similarity) to a clone of classical vibrios (ribotype I) and was only between 27.2 and 56.1% similar to clusters of El Tor, O139, and two other non-O1 nontoxigenic clones.
霍乱在孟加拉国呈地方性流行，且霍乱流行呈现出规律的季节性模式。我们研究了在孟加拉国流行期和流行间期分离出的103株属于O1、O139或非O1非O139血清群的霍乱弧菌临床和环境分离株之间的克隆关系，并将它们与来自亚洲和非洲四个国家的51株霍乱弧菌分离株进行了比较。这些研究通过对rRNA基因（核糖型）的限制性内切酶切割模式进行计算机辅助数值分析来完成。对BglI和HindIII产生的条带模式进行非加权配对组聚类分析，揭示了16个聚类。核糖型被定义为相似度>98%的菌株聚类。结果表明，154株分离株可分为15种不同的核糖型，其中3种核糖型（核糖型I、V、VIIIA和VIIIB）的菌株在孟加拉国流行期的分离频率高于流行间期。古典生物型弧菌属于六种不同的核糖型（核糖型I至VI），平均相似系数为0.84，而埃尔托生物型弧菌属于五种不同的核糖型（核糖型VIIIA和IX至XII），平均相似系数为0.82。坦桑尼亚存在单一克隆的埃尔托生物型弧菌（核糖型XII），而尼日利亚、叙利亚和印度与孟加拉国共享产毒的埃尔托菌株。从孟加拉国和印度分离出的霍乱毒素（CT）阳性O139弧菌属于单一核糖型（核糖型VIIIB），与埃尔托生物型弧菌的一种核糖型（核糖型VIIIA）相似度>98%，但来自阿根廷的一株CT阴性O139弧菌（核糖型XIII）与同一埃尔托生物型弧菌群的相似度<75%，这表明O139弧菌可能有不止一个起源。在孟加拉国，属于相同核糖型（核糖型VIII至X）的菌株从患者和地表水均有分离，表明可能通过地表水传播。一株CT阳性的非O1霍乱弧菌环境分离株（核糖型VII）的克隆被发现与古典生物型弧菌的一个克隆（核糖型I）密切相关（相似度76.3%），与埃尔托生物型、O139以及另外两个非O1非产毒克隆的聚类相似度仅在27.2%至56.1%之间。
