Molecular characterization of Clostridium botulinum isolates from foodborne outbreaks in Thailand, 2010.
BACKGROUND
Thailand has had several foodborne outbreaks of botulism, one of the biggest being in 2006 when laboratory investigations identified the etiologic agent as Clostridium botulinum type A. Identification of the etiologic agent from outbreak samples is laborious using conventional microbiological methods and the neurotoxin mouse bioassay. Advances in molecular techniques have added enormous information regarding the etiology of outbreaks and characterization of isolates. We applied these methods in three outbreaks of botulism in Thailand in 2010.


RESULTS
A total of 19 cases were involved (seven each in Lampang and Saraburi and five in Maehongson provinces). The first outbreak in Lampang province in April 2010 was associated with C. botulinum type F, which was detected by conventional methods. Outbreaks in Saraburi and Maehongson provinces occurred in May and December were due to C. botulinum type A1(B) and B that were identified by conventional methods and molecular techniques, respectively. The result of phylogenetic sequence analysis showed that C. botulinum type A1(B) strain Saraburi 2010 was close to strain Iwate 2007. Molecular analysis of the third outbreak in Maehongson province showed C. botulinum type B8, which was different from B1-B7 subtype. The nontoxic component genes of strain Maehongson 2010 revealed that ha33, ha17 and botR genes were close to strain Okra (B1) while ha70 and ntnh genes were close to strain 111 (B2).


CONCLUSIONS
This study demonstrates the utility of molecular genotyping of C. botulinum and how it contributes to our understanding the epidemiology and variation of boNT gene. Thus, the recent botulism outbreaks in Thailand were induced by various C. botulinum types.
Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand.
Piyada
P
Wangroongsarb
Department of Veterinary Science, Osaka Prefecture University, Osaka, Japan.
Tomoko
T
Kohda
Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand.
Chutima
C
Jittaprasartsin
Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand.
Karun
K
Suthivarakom
Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand.
Thanitchi
T
Kamthalang
Department of Microbiology, Osaka City Institute of Public Health and Environmental Sciences, Osaka, Japan.
Kaoru
K
Umeda
Department of Medical Sciences, Nonthaburi, Thailand.
Pathom
P
Sawanpanyalert
Department of Veterinary Science, Osaka Prefecture University, Osaka, Japan.
Shunji
S
Kozaki
Department of Virology, Osaka University, Osaka, Japan.
Kazuyoshi
K
Ikuta
D000818:Animals; D001483:Base Sequence; D001681:Biological Assay; D001906:Botulism / Q000453:epidemiology* / Q000382:microbiology; D003014:Clostridium botulinum / Q000235:genetics*; D016000:Cluster Analysis; D004196:Disease Outbreaks / Q000266:history / Q000706:statistics & numerical data*; D004797:Enzyme-Linked Immunosorbent Assay; D049674:History, 21st Century; D006801:Humans; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D060885:Multiplex Polymerase Chain Reaction; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013785:Thailand / Q000453:epidemiology