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Molecular characterization of Salmonella enterica Serotype Typhi isolates by pulsed-field gel electrophoresis in Hong Kong, 2000-2004.
Foodborne Pathog Dis. 2007 Spring; 4(1):41-9.FP

Abstract

OBJECTIVE

To study Salmonella enterica serotype Typhi by pulsed-field gel electrophoresis in Hong Kong.

MATERIALS AND METHODS

One hundred thirty four isolates of Salmonella enterica serotype Typhi collected from 17 public hospitals and clinics in Hong Kong from 2000 to 2004 were studied in relation to epidemiological and clinical events. Isolates originated from 80 patients, with 29 patients providing multiple isolates. Susceptibility to six antibiotics was tested: ampicillin, trimethoprim-sulfamethoxazole, tetracycline, chloramphenicol, nalidixic acid, and ciprofloxacin. Strains were further subtyped by pulsed-field gel electrophoresis (PFGE) by separating XbaI-restricted genomic DNA of isolates. PFGE patterns that were shared between strains were further examined using restriction enzyme BlnI.

RESULTS

Of 134 S. Typhi isolates, 29 (21.6%) were resistant to at least one and up to five of the antibiotics tested. Using restriction fragments between 20 and 700 kb for analysis, the number of fragments generated by XbaI ranged from 14 to 20. Sixty-six distinct subtypes were identified in the first isolates of all 80 patients (epidemiologically unrelated) with a Simpson index of 0.993, indicating a high degree of diversity among these S. Typhi isolates. Multidrug-resistant and travel-associated S. Typhi appeared to cluster more closely than the rest of strains. Further analysis of PFGE patterns investigated the temporal relationships between the 83 strains collected from the 29 patients who gave multiple isolates.

CONCLUSION

Dual infections or variants of the same isolates in the same patient occurred during the course of follow-up. These findings imply that PFGE data could be a valuable tool in predicting relapse, evaluating new antimicrobial drugs, and controlling the spread of typhoid disease. A regional, as well as global, typhoid bacillus fingerprint database should be set up to improve epidemiological investigations, as clinical cases easily move across national boundaries.

Authors+Show Affiliations

Division of Microbiology, Public Health Laboratory Service, Centre for Health Protection, Department of Health, Hong Kong, China. kmkam@dh.gov.hkNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17378707

Citation

Kam, Kai Man, et al. "Molecular Characterization of Salmonella Enterica Serotype Typhi Isolates By Pulsed-field Gel Electrophoresis in Hong Kong, 2000-2004." Foodborne Pathogens and Disease, vol. 4, no. 1, 2007, pp. 41-9.
Kam KM, Luey KY, Chiu AW, et al. Molecular characterization of Salmonella enterica Serotype Typhi isolates by pulsed-field gel electrophoresis in Hong Kong, 2000-2004. Foodborne Pathog Dis. 2007;4(1):41-9.
Kam, K. M., Luey, K. Y., Chiu, A. W., Law, C. P., & Leung, S. F. (2007). Molecular characterization of Salmonella enterica Serotype Typhi isolates by pulsed-field gel electrophoresis in Hong Kong, 2000-2004. Foodborne Pathogens and Disease, 4(1), 41-9.
Kam KM, et al. Molecular Characterization of Salmonella Enterica Serotype Typhi Isolates By Pulsed-field Gel Electrophoresis in Hong Kong, 2000-2004. Foodborne Pathog Dis. 2007;4(1):41-9. PubMed PMID: 17378707.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Molecular characterization of Salmonella enterica Serotype Typhi isolates by pulsed-field gel electrophoresis in Hong Kong, 2000-2004. AU - Kam,Kai Man, AU - Luey,Kit Yee, AU - Chiu,Agatha Wai Huen, AU - Law,Choi Ping, AU - Leung,Susanna Fung Sim, PY - 2007/3/24/pubmed PY - 2007/5/1/medline PY - 2007/3/24/entrez SP - 41 EP - 9 JF - Foodborne pathogens and disease JO - Foodborne Pathog Dis VL - 4 IS - 1 N2 - OBJECTIVE: To study Salmonella enterica serotype Typhi by pulsed-field gel electrophoresis in Hong Kong. MATERIALS AND METHODS: One hundred thirty four isolates of Salmonella enterica serotype Typhi collected from 17 public hospitals and clinics in Hong Kong from 2000 to 2004 were studied in relation to epidemiological and clinical events. Isolates originated from 80 patients, with 29 patients providing multiple isolates. Susceptibility to six antibiotics was tested: ampicillin, trimethoprim-sulfamethoxazole, tetracycline, chloramphenicol, nalidixic acid, and ciprofloxacin. Strains were further subtyped by pulsed-field gel electrophoresis (PFGE) by separating XbaI-restricted genomic DNA of isolates. PFGE patterns that were shared between strains were further examined using restriction enzyme BlnI. RESULTS: Of 134 S. Typhi isolates, 29 (21.6%) were resistant to at least one and up to five of the antibiotics tested. Using restriction fragments between 20 and 700 kb for analysis, the number of fragments generated by XbaI ranged from 14 to 20. Sixty-six distinct subtypes were identified in the first isolates of all 80 patients (epidemiologically unrelated) with a Simpson index of 0.993, indicating a high degree of diversity among these S. Typhi isolates. Multidrug-resistant and travel-associated S. Typhi appeared to cluster more closely than the rest of strains. Further analysis of PFGE patterns investigated the temporal relationships between the 83 strains collected from the 29 patients who gave multiple isolates. CONCLUSION: Dual infections or variants of the same isolates in the same patient occurred during the course of follow-up. These findings imply that PFGE data could be a valuable tool in predicting relapse, evaluating new antimicrobial drugs, and controlling the spread of typhoid disease. A regional, as well as global, typhoid bacillus fingerprint database should be set up to improve epidemiological investigations, as clinical cases easily move across national boundaries. SN - 1535-3141 UR - https://www.unboundmedicine.com/medline/citation/17378707/Molecular_characterization_of_Salmonella_enterica_Serotype_Typhi_isolates_by_pulsed_field_gel_electrophoresis_in_Hong_Kong_2000_2004_ L2 - https://www.liebertpub.com/doi/10.1089/fpd.2006.59?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -