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[Shigellae isolated in 1997--plasmid profiles and antibiotic resistance]
Z Jelesić1, M Kulauzov, G Kozoderović
1Institut za zastitu zdravlja. Medicinski fakultet, Novi Sad.
Introduction:
Shigella spp is one of the most frequently isolated bacteria causing acute diarrhea with us. Genetics of pathogenicity of Shigella spp. includes chromosomal and plasmid genes. Most virulence factors are coded by invasion plasmid antigen genes residing on a 180-230 MDa plasmid. There is a big problem with multiple resistance of Shigella spp. strains, which is mostly plasmid-borne. Genetic analysis of bacterial cells, that is plasmid profile analysis, is important for investigation of sources and ways of spreading of the infection. All isolates originating from the same clone have identical plasmid profiles, i.e. number and size of plasmids. The aim of the investigation was: comparing the type of resistance to antimicrobical agents found in epidemic and nonepidemic. Shigella strains isolated in 1997, analyzing plasmid profiles of these isolates and confirming their epidemic connection.
Material And Methods:
Susceptibility to antibiotics was examined by a standard disc-diffusion method. Plasmid profiles of 40 strains (20 from the outbreak and 20 from sporadic cases) were tested using a method of alkaline lysis by Birnboim and Doly followed by electrophoresis in agarose gel.
Results:
Shigella strains were resistant to antimicrobial agents which are most commonly used. Epidemic isolates shared the same resistance type, they were resistant to cephalexin, streptomycin and co-trimoxazole. The dominant type of resistance of nonepidemic strains was to ampicillin, streptomycin and co-trimoxazole. Strains isolated during the outbreak had identical plasmid profiles (2 plasmid bands of 55 and 1.5 MDa). Non-epidemic isolates had different plasmid profiles as well as type of resistance.
Conclusion:
Strains of Shigella spp. isolated during an outbreak had the same type of resistance and the same plasmid profiles, which indicated their origin from the same clone. The plasmid profile analysis is a reliable and precise method for determination of epidemic connection of Shigella isolates.
Insights
Epidemic Shigella strains showed identical resistance patterns and plasmid profiles, confirming their shared origin from a single clone. Plasmid profile analysis is a reliable method for tracking infectious disease outbreaks.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Context:
- Shigella species are a leading cause of bacterial acute diarrhea.
- Multiple drug resistance in Shigella is a significant public health concern, often plasmid-mediated.
- Understanding the genetic basis of Shigella pathogenicity and resistance is crucial for infection control.
Purpose:
- To compare antimicrobial resistance patterns between epidemic and non-epidemic Shigella strains.
- To analyze plasmid profiles of Shigella isolates to determine epidemic connections.
- To confirm the clonal origin of Shigella strains during a 1997 outbreak.
Summary:
- Epidemic Shigella isolates exhibited a uniform resistance profile (cephalexin, streptomycin, co-trimoxazole) and identical plasmid profiles (55 and 1.5 Mda bands).
- Non-epidemic strains displayed varied resistance types and distinct plasmid profiles.
- These findings indicate that epidemic strains originated from a common clone.
Impact:
- Plasmid profile analysis is validated as a precise tool for establishing epidemiological links in Shigella infections.
- This study aids in tracing the source and spread of Shigella outbreaks.
- The results contribute to effective strategies for managing and preventing Shigella infections.