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Multiresistant Shigella species isolated from pediatric patients with acute diarrheal disease
A Flores1, M Araque, L Vizcaya
1Department of Microbiology and Parasitology, Faculty of Pharmacy, University of The Andes, Mérida, Venezuela.
Insights
Multidrug-resistant Shigella strains, particularly trimethoprim-resistant Shigella sonnei and Shigella flexneri, are prevalent in Venezuela. Surveillance is crucial for understanding local antimicrobial resistance patterns and guiding effective treatment strategies.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Shigella infections cause significant diarrheal disease globally.
- Antimicrobial resistance in Shigella poses a major public health challenge.
- Understanding local resistance patterns is vital for effective treatment.
Purpose of the Study:
- To determine the antimicrobial susceptibility patterns of Shigella strains isolated from children in Merida, Venezuela.
- To identify the prevalence of multidrug-resistant Shigella sonnei and Shigella flexneri.
- To inform local empiric therapy guidelines.
Main Methods:
- Agar dilution method was used to test susceptibility.
- 57 Shigella strains (36 S. sonnei, 21 S. flexneri) were analyzed.
- Testing included resistance to trimethoprim, sulfamethoxazole, ampicillin, and other agents.
Main Results:
- High-level trimethoprim resistance was observed in 75% of S. sonnei and 38.1% of S. flexneri.
- Common resistance phenotypes included trimethoprim-sulfamethoxazole-streptomycin and trimethoprim-sulfamethoxazole-ampicillin-streptomycin.
- Most strains exhibited resistance to three or more antimicrobial agents.
Conclusions:
- Multidrug-resistant Shigella strains are present in Merida, Venezuela.
- Trimethoprim resistance is a significant issue in both S. sonnei and S. flexneri.
- Ongoing surveillance is essential to monitor antimicrobial susceptibility and guide therapy.
Abstract:
A total of 57 strains of Shigella (36 S sonnei, 21 S flexneri), isolated from children with acute diarrheal disease who presented for treatment at the Andes University Hospital, Merida, Venezuela, from June 1993 to June 1995, were tested for their susceptibility to trimethoprim, sulfamethoxazole, ampicillin, cefamandole, ceftriaxone, streptomycin, fleroxacin, and nalidixic acid, by the agar dilution method. Twenty-seven strains (75%) of S sonnei and eight strains of S flexneri (38.1%) isolates showed high-level resistance to trimethoprim (MIC90 > 1024 microg/mL), which was also associated with other resistance patterns. The most common resistant phenotype associated with trimethoprim-resistance among S sonnei isolates was sulfamethoxazole-streptomycin (63%); among S flexneri isolates, it was sulfamethoxazole-ampicillin-streptomycin (87.5%). Individual resistance was only observed for ampicillin, mainly in four isolates of S flexneri, and in one isolate of S sonnei. Most Shigella strains were resistant to three or more antimicrobial agents. These results confirmed that multiresistant strains of Shigella are present in Merida, and emphasize the importance to maintain these under surveillance in order to assess local susceptibility patterns and empiric therapy.