Molecular epidemiology of drug-resistant Salmonella Typhimurium in Spain.

One hundred and forty-seven Salmonella serotype Typhimurium strains isolated in three provinces in the midwest of Spain were studied. Of these, 93.6% were drug resistant. There were two predominant resistance phenotypes: 43 isolates (29.3%) were resistant to amoxicillin, tetracyclines, chloramphenicol, streptomycin and sulphamethoxazole and 27 isolates (18.4%) to amoxicillin, amoxicillin/clavulanic acid, tetracyclines, chloramphenicol, streptomycin and sulphamethoxazole. Randomly amplified polymorphic DNA (RAPD) analysis and pulsed field gel electrophoresis (PFGE) were performed for molecular typing. Thirty-six DNA band profiles were differentiated by RAPD, and 38 by PFGE. We found a high level of clonality; 27% of strains were identical by both methods. There were additional smaller clonal lines within every area. The highest discriminatory power was obtained with PFGE, but the greatest degree of genetic diversity was observed among Salmonella Typhimurium using both RAPD and PFGE.

Molecular epidemiology of drug-resistant Salmonella Typhimurium in Spain

One hundred and forty-seven Salmonella serotype Typhimurium strains isolated in three provinces in the midwest of Spain were studied. Ofthese, 93.6% were drug resistant. There were two predominant resistance phenotypes: 43 isolates (29.3%) were resistant to amoxicillin, tetracyclines,chloramphenicol, streptomycin and sulphamethoxazole and 27 isolates (18.4%) to amoxicillin, amoxicillin/clavulanic acid, tetracyclines,chloramphenicol, streptomycin and sulphamethoxazole. Randomly amplified polymorphic DNA (RAPD) analysis and pulsed field gelelectrophoresis (PFGE) were performed for molecular typing. Thirty-six DNA band profiles were differentiated by RAPD, and 38 by PFGE. Wefound a high level of clonality; 27% of strains were identical by both methods. There were additional smaller clonal lines within every area.The highest discriminatory power was obtained with PFGE, but the greatest degree of genetic diversity was observed among SalmonellaTyphimurium using both RAPD and PFGE

Se estudiaron 147 de cepas de Salmonella serotipificadas como Typhimurium procedentes de tres provincias españolas del medio-oeste. El93,6% de ellas eran resistentes a los antimicrobianos. Hubo dos fenotipos de resistencia predominantes: 43 cepas (29,3%) fueron resistentesa amoxicilina, tetraciclinas, cloranfenicaol, estreptomicina y sulfametoxazol, y 27 (18,4%) a amoxicilina, amoxicilina-ácido clavulánico, tetraciclinas,cloranfenicol, estreptomicina y sulfametoxazol. Los distintos patrones de resistencia se determinaron por técnicas de biología molecular:RAPD (Randomly Amplified Polymorphic DNA) y PFGE (Pulsed Field Gel Electrophoresis). Por RAPD se diferenciaron 36 patrones debandas, y por PFGE 38. Se encontró una proporción alta de clones: el 27% de las cepas fueron idénticas por ambos métodos. Además, encada área se encontraron algunos clones diferentes adicionales. Con PFGE se obtuvo el mayor poder discriminatorio, pero el mayor gradode diversidad genética se observó usando ambas técnicas conjuntamente