Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan.
Prek Leap National Institute of Agriculture, Phnom Penh, Cambodia.
Transbound Emerg Dis. 2022 May;69(3):1641-1648. doi: 10.1111/tbed.14077. Epub 2021 Mar 30.
Rats are an important maintenance host of Leptospira spp., the causative agents of leptospirosis, a zoonotic disease with worldwide distribution. Rats are traded as food in the Mekong Delta, where Cambodia exports tons of rats to Vietnam. Handling wild rats is a potential health risk, but the information on Leptospira spp. carried by rats traded in the region remains limited. In this study, we investigated the carriage of Leptospira spp. in rats exported from Cambodia to Vietnam using bacterial culture, nested PCR and DNA sequencing. Isolates were then assessed using serological analysis and whole-genome sequencing (WGS), and Leptospira DNA detected in rat kidney tissues was also analysed by multilocus sequence typing (MLST). Seventy-two rats (2 Bandicota indica, 57 Rattus argentiventer, 11 R. losea, 1 R. norvegicus and 1 R. rattus) were subjected to bacterial culture, and three L. borgpetersenii serogroup Javanica isolates were obtained from R. argentiventer (5.3%). WGS revealed that although Cambodian isolates were genetically related to L. borgpetersenii serogroup Javanica strains widely distributed in East and South-East Asian countries, they formed a different cluster from other strains. In addition to the three L. borgpetersenii sequences, the flaB sequence of L. interrogans was detected in 18 R. argentiventer and 7 R. losea kidney tissue samples (38.9%) using nested PCR followed by DNA sequencing. The L. interrogans flaB-positive samples were further analysed by MLST, revealing that seven housekeeping genes (glmU, pntA, sucA, tpiA, pfkB, mreA and caiB) contained novel sequences with distinct lineages from other sequence types. This study revealed a high prevalence of Leptospira spp. among rats exported from Cambodia to Vietnam, indicating a potential risk to people engaging in rat trade and demonstrating that a fastidious L. interrogans strain circulates among Cambodian rats.
鼠类是钩端螺旋体属（Leptospira spp.）的重要维持宿主，后者是钩端螺旋体病（一种具有世界性分布的人畜共患病）的病原体。在湄公河三角洲，柬埔寨出口大量的鼠类作为食物，那里的人们交易野生鼠类。处理野生鼠类可能会带来健康风险，但该地区交易的鼠类携带的钩端螺旋体属信息仍然有限。在这项研究中，我们使用细菌培养、巢式 PCR 和 DNA 测序来调查从柬埔寨出口到越南的鼠类携带的钩端螺旋体属情况。然后使用血清学分析和全基因组测序（WGS）评估分离株，并通过多位点序列分型（MLST）分析鼠肾组织中检测到的钩端螺旋体 DNA。对 72 只鼠类（2 只邦加短尾鼩、57 只银鼠、11 只沟齿鼩、1 只褐家鼠和 1 只褐鼠）进行了细菌培养，从银鼠中获得了 3 株 Javanica 血清群的伯氏钩端螺旋体（5.3%）。WGS 表明，尽管柬埔寨分离株在遗传上与广泛分布于东亚和东南亚国家的 Javanica 血清群伯氏钩端螺旋体有关，但它们与其他菌株形成了不同的聚类。除了 3 株伯氏钩端螺旋体外，使用巢式 PCR 随后进行 DNA 测序，在 18 只银鼠和 7 只沟齿鼩的肾脏组织样本中检测到 L.interrogans 的 flaB 序列（38.9%）。进一步通过 MLST 分析 L.interrogans flaB 阳性样本，揭示了 7 个看家基因（glmU、pntA、sucA、tpiA、pfkB、mreA 和 caiB）包含与其他序列类型不同的新序列的独特谱系。本研究表明，从柬埔寨出口到越南的鼠类中钩端螺旋体属的流行率很高，这表明从事鼠类贸易的人群存在潜在风险，并表明一种挑剔的 L.interrogans 菌株在柬埔寨鼠类中传播。
