A genomic dissection of travel associated ESBL producing Salmonella Typhi originating from the Philippines - A one-off occurrence or threat to the effective treatment of typhoid?. S. Typhi ESBL

ESBL producing Typhi has only been confirmed in a few cases. We surveyed the global occurrence and identified one new case. This resembled epidemiological a previously published strain why the two were compared by whole genome sequencing. Both isolates were acquired in the Philippines in 2007. They shared the same susceptibility profile, contained the same antimicrobial resistance genes; blaSHV-12, blaTEM-1, aac(6')IIc, strA, strB, tetD, and dfrA18, belonged to MLST ST1, haplotype H13, no chromosomal or plasmid SNP differences, and contained the incHI2/HI2A of 280 kb. Minor differences were observed in pulsotypes and one isolate contained a 144kb deletion of the SPI-7. These isolates likely belong to an undetected outbreak. The question is if this is a one-off occurrence or a threat to the future effective treatment of typhoid fever with severe public health implications – we call for a survey to search for persistence.

产超广谱β-内酰胺酶（Extended-Spectrum Beta-Lactamases, ESBL）的伤寒沙门菌（Typhi）仅在少数病例中得到证实。本研究针对该菌的全球流行态势开展了调查，并新发现1例感染病例。该菌株与此前已发表的一株菌株在流行病学特征上高度相似，因此我们通过全基因组测序对两株分离菌进行了比对分析。两株分离菌均于2007年在菲律宾分离获得。二者具有一致的药物敏感性谱，携带blaSHV-12、blaTEM-1、aac(6')IIc、strA、strB、tetD及dfrA18等全套抗菌药物耐药基因；隶属于多位点序列分型（Multi-Locus Sequence Typing, MLST）ST1型，单倍型H13；二者在染色体及质粒层面均无单核苷酸多态性（Single Nucleotide Polymorphism, SNP）差异，且均携带280 kb的IncHI2/HI2A型质粒。脉冲分型存在细微差异，其中一株分离菌携带144 kb的沙门菌致病岛7（Salmonella Pathogenicity Island 7, SPI-7）缺失片段。上述两株分离菌大概率属于一起未被发现的暴发疫情。当前亟需明确的核心问题是：此类感染究竟属于单次偶发事件，还是会对未来伤寒的有效治疗构成潜在威胁？这一问题具备重大公共卫生意义，因此我们呼吁开展专项调查以明确其是否存在持续传播态势。