Differentiation and identification of Shigella spp. and enteroinvasive Escherichia coli in environmental waters by a molecular method and biochemical test.
Both Shigella spp. and enteroinvasive Escherichia coli (EIEC) are important human pathogens that are responsible for the majority of cases of endemic bacillary dysentery. However, they are difficult to identify and differentiate by biochemical tests or molecular methods alone. In this study, we developed a procedure to detect Shigella spp. and EIEC from environmental water samples using membrane filtration followed by nutrient broth enrichment, isolation using selective culture plates, and identification of the invasion plasmid antigen H (ipaH) gene by PCR amplification and DNA sequencing. Finally, we used a biochemical test and a serological assay to differentiate between Shigella and EIEC. Among the 93 water samples from nine reservoirs and one watershed, 76 (81.7%) water samples of culture plates had candidate colonies of Shigella and EIEC and 5 water samples were positive (5.4%) for a Shigella- and EIEC-specific polymerase chain reaction targeting the ipaH gene. Guided by the molecular method, the biochemical test, and the serological assay, 11 ipaH gene-positive isolates from 5 water samples were all identified as EIEC.
Hsu
Bing-Mu
BM
Department of Earth and Environmental Sciences, National Chung Cheng University, Chiayi 621, Taiwan, ROC. bmhsu@ccu.edu.tw
Wu
Shu-Fen
SF
Huang
Shih-Wei
SW
Tseng
Yu-Jung
YJ
Ji
Dar-Der
DD
Chen
Jung-Sheng
JS
Shih
Feng-Cheng
FC
D000942:Antigens, Bacterial / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques / Q000379:methods*; D004783:Environmental Microbiology; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification*; D029968:Escherichia coli Proteins / Q000235:genetics; D005843:Geography; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D010802:Phylogeny; D045483:Rivers / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D012698:Serologic Tests; D012760:Shigella / Q000235:genetics* / Q000302:isolation & purification*; D013624:Taiwan; D014881:Water Supply
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C507120:ipaH protein, E coli; C063500:ipaH protein, Shigella flexneri