Volume 40, Number 6, December 2007
| | Clinical characteristics of non-O1/non-O139 Vibrio cholerae isolates and polymerase chain reaction analysis of their virulence factors |
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Ya-Ling Lee1, Po-Pin Hung1, Che-An Tsai1, Yu-Hui Lin1, Chun-Eng Liu2, Zi-Yuan Shi1
1Division of Infectious Disease, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung; and 2Division of Infectious Disease, Department of Internal Medicine, Changhua Christian Hospital, Changhua, Taiwan
Received: July 19, 2006 Revised: August 25, 2006 Accepted: August 30, 2006
Corresponding author: Dr. Zi-Yuan Shi, Division of Infectious Disease, Taichung Veterans General Hospital, No.160, Section 3, Chung Kang Road, Taichung 407, Taiwan. E-mail:
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Background and Purpose: Non-O1/non-O139 Vibrio cholerae can cause invasive extraintestinal disease as well as enteritis. The pathogenesis of invasive non-O1/non-O139 V. cholerae infections remains to be determined. This study compared the clinical manifestations and predisposing factors between bacteremic and non-bacteremic non-O1/non-O139 V. cholerae infections and examined virulence-associated genes in the pathogenic strains causing invasive disease.
Methods: We retrospectively investigated clinical characteristics of 18 bacteremic patients and 18 non-bacteremic patients, including demographic, laboratory and clinical data. Fourteen clinical isolates (ten isolated from blood and four from stool specimens) were obtained for polymerase chain reaction tests of the presence of virulence-associated genes ctxA, ctxB and tcpA.
Results: There was no difference in age, gender and gastrointestinal symptoms including abdominal pain and diarrhea, laboratory findings including leukocytosis and anemia, or underlying immunocompromised condition, except cirrhosis, between the bacteremic and non-bacteremic groups. Compared to patients with non-bacteremic infections, patients with non-O1/non-O139 V. cholerae bacteremia were significantly more likely to have cirrhosis and thrombocytopenia (0.0% vs 77.8% and 5.9% vs 72.2%, respectively; p<0.001). The cholera toxin genes (ctxA and ctxB) were found in only one strain (isolated from the stool specimen of a patient with enteritis) among fourteen clinical strains (7%). The tcpA gene, encoding the toxin-coregulated pilus, was present in thirteen of fourteen isolates (93%) [including ten isolates from blood, and three isolates from stool specimens].
Conclusions: Cirrhotic patients with thrombocytopenia were vulnerable to non-O1/non-O139 V. cholerae bloodstream invasion. The low prevalence of ctxA and ctxB genes in stool specimens indicates other toxins could have contributed to diarrhea. The fact that the tcpA gene was highly prevalent in clinical isolates in this study could imply an important role of tcpA in the pathogenesis of invasive disease caused by non-O1/non-O139 V. cholerae.
Key words: Bacteremia; Cholera toxin; Vibrio cholerae O139; Vibrio cholerae non-O1; Virulence factors
J Microbiol Immunol Infect. 2007;40:474-480.
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