Phenotypic and molecular characterization of a shigellosis outbreak in Antofagasta, Chile, during the year 2008

Abstract number: P1161

Silva J., Gaona J., Herrera N., Chambel C., Alcaide B., Guerrero K., Gonzalez D., Valenzuela N., Marcoleta A., del Campo R.

Objectives: Shigellosis is a major cause of diarrhea with a high morbidity and mortality, especially in the developing countries, being Shigella flexneri the more frequent specie detected in South America. During the year 2008, we observed a dramatically increase in the Shigella sonnei incidence from patients attended in different Health Centers of Antofagasta (North of Chile). The aim of this work was to analyze the phenotypic and molecular characteristics of these strains.

Methods: We recovered prospectively (January-June 2008) information about identification, serology and antibiotic susceptibility of 265 Shigella isolates obtained in three different Health Centers: a Public Hospital, a Private Clinic, and a Primary Health Center. Biochemical and serological tests were applied for specie identification, which was confirmed by specific PCR amplifications. Antimicrobial susceptibility to ampicillin (AM), ceftriaxone (CTR), ciprofloxacin (CIP), cloramphenicol (CH), cotrimoxazole (SXT), and nitrofurantoin (NF) was determined by the agar dilution method. Plasmid presence was analyzed in all strains and their genetic diversity was explored by PFGE.

Results: Specie identification of the isolates corresponded to S. sonnei (79%), S. flexneri (13%), S. boydii (3%), S. dysenteriae (2%) and Shigella spp (3%). About 50% of the diarrhea process in children with leqslant R: less-than-or-eq, slant10 years was caused by S. sonnei, and we focused our study in forty randomized isolates (23 from children and 17 from adults) of this specie. Most of patients were living in the same geographic zone; the north area of Antofagasta, supporting that contaminated water was the most probably the cause of the disease. High resistance to ampicillin (94%), chloramphenicol (89%) and cotrimoxazole (89%) was detected in these strains, being the 84% of the strains co-resistant to the three antibiotics. A particular plasmid was observed in almost all forty isolated. Genetic PFGE studies revealed that 95% of S. sonnei isolates grouped in the same clone.

Conclusion: We detected a Sighella sonnei outbreak in our region, affecting different patients from different Health Centers, being contaminated water the most probable route of transmission.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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