Genetic diversity and molecular typing of Listeria monocytogenes  in China.
BACKGROUND
Listeria monocytogenes can cause invasive diseases in humans and farm animals and is frequently isolated from dairy products and poultry. Listeriosis is uncommon in China but L. monocytogenes has been isolated from foods and food processing environments in China. However little is known of genetic diversity of Chinese L. monocytogenes isolates and their relationships with global isolates.


RESULTS
Two hundred and twelve isolates of L. monocytogenes from food sources from 12 provinces/cities in China were analysed by serotyping, Pulsed Field Gel Electrophoresis (PFGE) and Multi-locus Sequence Typing (MLST). The predominant serotypes are 1/2a, 1/2b and 1/2c accounting for 90.1% of the isolates. PFGE divided the isolates into 61 pulse types (PTs). Twenty nine PTs were represented by more than one isolates with PT GX6A16.0004 containing the most number of isolates. MLST differentiated the isolates into 36 STs, among which 15 were novel. The 3 most common STs were ST9 (29.1%), ST8 (10.7%) and ST87 (9.2%), accounting for 49.0% of the isolates.


CONCLUSIONS
STs prevalent in other parts of the world are also prevalent in China including 7 STs (ST1-ST3, ST5, ST6, ST8, ST9) which caused maternal fetal infections or outbreaks, suggesting that these STs potentially can also cause severe human infections or outbreaks in China. Surveillance of these STs will provide important information for prevention of listeriosis. This study also enhances our understanding of genetic diversity of L. monocytogenes in China.
State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, China CDC, Changbai Road 155, Changping, Beijing, China.
Yan
Y
Wang
Ailan
A
Zhao
Renfa
R
Zhu
Ruiting
R
Lan
Dong
D
Jin
Zhigang
Z
Cui
Yonglu
Y
Wang
Zhenchuan
Z
Li
Yiting
Y
Wang
Jianguo
J
Xu
Changyun
C
Ye
D000818:Animals; D002681:China; D016521:Electrophoresis, Gel, Pulsed-Field; D005516:Food Microbiology; D014644:Genetic Variation; D006801:Humans; D008089:Listeria monocytogenes / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D008088:Listeriosis / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D012703:Serotyping