Spss cluster analysis software

The preparation of samples was performed as previously described [15 (link)]. DNA restriction was done with ApaI enzyme (Thermo Scientific, Lithuania) at 37^°C for 3 hours. PFGE was performed with a 2015 Pulsafor unit (LKB Instruments, Broma, Sweden) equipped with a hexagonal electrode array for 16h at 300V at 9^°C. The gels were stained with ethidium bromide and photographed under UV illumination. A dendrogram was derived from the Ward linkage of correlation coefficients between PFGE patterns of different genotypes by using SPSS cluster analysis software (IBM Corp. Released 2012. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp.).

Bacterial strains used in this study originated from patients (n = 182) followed at the National Cystic Fibrosis Centre which is located at the Mother and Child Health Care Institute of Serbia “Dr. Vukan Cupic”. All of the strains were characterized previously by our research group [13 ].
Their genetic relatedness was determined by pulsed-field gel electrophoresis (PFGE) analysis of SpeI macrorestriction profiles. Fourteen different genotypes were identified and they belonged to four different MLST types: B. cenocepacia ST856 (11 genotypes), B. cenocepacia ST858 (one genotype), B. cenocepacia ST859 (one genotype) and B. stabilis ST857 (one genotype) [13 ]. A dendrogram was derived from the Ward linkage of correlation coefficients between PFGE patterns of different genotypes using SPSS cluster analysis software (IBM Corp. Released 2012. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp.).

Genetic relatedness among analyzed isolates was determined by PFGE analysis of XbaI digested genomic DNA. Electrophoresis was carried out for 18 h using contour-clamped homogeneous electric field system (2015 Pulsafor unit; LKB Pharmacia, Sweden) in 0.5X TBE (45 mmol/l Tris base, 45 mmol/l boric acid, and 1 mmol/l EDTA pH 8), as described previously (Barton et al., 1995 (link)). A dendrogram was derived from the Ward linkage of correlation coefficients between PFGE patterns of different genotypes by using SPSS cluster analysis software (IBM Corp. Released 2012. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp.). Tenover's criteria were used for the interpretation of PFGE results (Tenover et al., 1995 (link)).