Saito Shioko, Iwade Yoshito, Tokuoka Eisuke, Nishio Tomohiro, Otomo Yoshimitsu, Araki Emiko, Konuma Hirotaka, Nakagawa Hiroshi, Tanaka Hiroyuki, Sugiyama Kanji, Hasegawa Akio, Sugita-Konishi Yoshiko, Hara-Kudo Yukiko
1 Akita Research Center for Public Health and Environment , Akita, Japan .
Foodborne Pathog Dis. 2015 Feb;12(2):131-8. doi: 10.1089/fpd.2014.1810.
Vibrio parahaemolyticus carrying the tdh gene, encoding the thermostable direct hemolysin (TDH), or the trh gene, encoding the TDH-related hemolysin (TRH), are both considered virulent strains. There are, however, disproportionally fewer reports of infections caused by seafood contaminated with trh-positive strains than by seafood contaminated with tdh-positive strains. Bivalves such as clams and oysters are the major seafood varieties associated with the infections. In this study, the prevalence of strains possessing the tdh and trh genes was investigated in Japan in 74 samples collected in 2007-2008 and in 177 samples collected in 2010 of domestic bivalves, bloody clams, hen clams, short-neck clams, and rock oysters. The tdh-positive and trh-negative, tdh-negative and trh-positive, and tdh-positive and trh-positive samples represented 5.4%, 12.2%, and 4.1% of all samples collected in 2007-2008, and 5.1%, 18.6%, and 5.6% of all samples collected in 2010, respectively. As determined by polymerase chain reaction, the prevalence of tdh negative and trh positive in all samples was two to four times higher than that of tdh positive and trh negative. In the samples collected in 2010, the tdh-negative and trh-positive V. parahaemolyticus (20 samples) was more often isolated than tdh-positive and trh-negative V. parahaemolyticus (7 samples). The most common serotype of tdh-positive isolates (22 of 24 strains) was pandemic O3:K6. The trh-positive isolates (61 strains) were various serotypes including OUT:KUT. In 330 V. parahaemolyticus outbreaks and sporadic infections in Japan, most outbreaks and sporadic infections were caused by tdh-positive and trh-negative strains (89.4%). The frequencies of infections caused by tdh-negative and trh-positive, and both tdh- and trh-positive strains were 1.2% and 3.0%, respectively. This finding suggests that the virulence of trh might be less than that of tdh, although trh-positive V. parahaemolyticus frequently contaminated bivalves.
携带编码耐热直接溶血素（TDH）的tdh基因或编码TDH相关溶血素（TRH）的trh基因的副溶血性弧菌均被视为有毒菌株。然而，与tdh阳性菌株污染的海鲜相比，trh阳性菌株污染的海鲜导致感染的报告却少得多。蛤和牡蛎等双壳贝类是与这些感染相关的主要海鲜品种。在本研究中，对2007 - 2008年采集的74份日本国内双壳贝类、血蛤、雌蛤、短颈蛤和岩牡蛎样本以及2010年采集的177份样本中携带tdh和trh基因的菌株的流行情况进行了调查。tdh阳性且trh阴性、tdh阴性且trh阳性以及tdh阳性且trh阳性的样本分别占2007 - 2008年采集的所有样本的5.4%、12.2%和4.1%，以及2010年采集的所有样本的5.1%、18.6%和5.6%。通过聚合酶链反应测定，所有样本中tdh阴性且trh阳性的流行率比tdh阳性且trh阴性的流行率高两到四倍。在2010年采集的样本中，tdh阴性且trh阳性的副溶血性弧菌（20份样本）比tdh阳性且trh阴性的副溶血性弧菌（7份样本）更常被分离出来。tdh阳性分离株（24株中的22株）最常见的血清型是大流行的O3:K6。trh阳性分离株（61株）是包括OUT:KUT在内的各种血清型。在日本的330起副溶血性弧菌暴发和散发性感染中，大多数暴发和散发性感染是由tdh阳性且trh阴性的菌株引起的（89.4%）。tdh阴性且trh阳性以及tdh和trh均阳性的菌株引起感染的频率分别为1.2%和3.0%。这一发现表明，尽管trh阳性的副溶血性弧菌经常污染双壳贝类，但其毒力可能低于tdh。
