title: Improving typeability of multiple bacterial species using pulsed-field gel electrophoresis and thiourea.
abstract: Although pulsed-field gel electrophoresis is considered the "gold standard" technique for molecular typing, typeability may not be excellent for some bacterial species because of DNA degradation. Previous reports suggest that the addition of thiourea in the gel buffer can improved the typeability for some species. In the present study, 66 Gram-negative strains (seven species) known to be affected by DNA degradation and four control strains were evaluated by PFGE with and without the addition of 50 microg/M of thiourea to the buffer used in the electrophoresis. Macrorestriction patterns were obtained for all K. pneumoniae, S. marcescens, P. aeruginosa, and Salmonella spp., for 95.4% of E. coli, and for 50% of E. cloacae strains from the gels performed in the buffer with throurea. However, typeability was not improved for Acinetobacter spp. The range of non-typeable species for which thiourea can limit the problem of DNA degradation is considerably wider than described in previous publications.
authors.affiliation: Laboratório Especial de Microbiologia Clínica, Disciplina de Doenças Infecciosas e Parasitárias, Universidade Federal de São Paulo, Rua Leandro Dupret, 188. CEP, São Paulo, Brazil. suzanesilbert@terra.com.br
authors.forename: Suzane
authors.initials: S
authors.lastname: Silbert
authors.forename: Linda
authors.initials: L
authors.lastname: Boyken
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Hollis
authors.forename: Michael A
authors.initials: MA
authors.lastname: Pfaller
mesh_terms: D015373:Bacterial Typing Techniques / Q000379:methods; D004269:DNA, Bacterial / Q000032:analysis*; D016521:Electrophoresis, Gel, Pulsed-Field; D006094:Gram-Positive Bacteria / Q000302:isolation & purification*; D006801:Humans; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D013890:Thiourea / Q000494:pharmacology*
chemical_list: D004269:DNA, Bacterial; D013890:Thiourea