Although type 2 plasmids showed higher conjugation capability, ty

Although type 2 plasmids showed higher conjugation capability, type 1 plasmids were the predominant plasmids responsible for MDR dissemination

in S. Braenderup. Methods Bacterial isolates Salmonella isolates were collected from 19 medical centers and district hospitals located throughout Taiwan from 2004 to 2007. Serotypes of the isolates were determined in the Salmonella Reference Laboratory of Centers for Disease Control (CDC), Department of Health, Taiwan, with antisera check details purchased from S&A Reagents Lab (Bangkok, Thailand), Denka Seiken (Tokyo, Japan), Statens Serum Institut (Copenhagen, Denmark), and a local biotech company, LTK Biolaboratories (Taoyuan, Taiwan). Phase induction was performed using a paper-bridged method developed by the Taiwan CDC [38]. In total, 51 S. Bareilly isolates and 45 S. Braenderup isolates collected in 2004 and Idasanutlin 2005 were selected for further characterization. Isolates were separated into two groups based on their geographic origin: the north Taiwan group, consisting of isolates collected from north of Taichung county (including Taichung county), and the south Taiwan group, consisting of isolates collected from south of Taichung county. Antimicrobial

susceptibility testing Antimicrobial susceptibility testing was performed using the disc diffusion method in accordance with the guidelines of the CLSI standards [39] with 7 antibiotics: ampicillin (AMP, 50 μg), chloramphenicol (CHL, 20 μg), kanamycin (KAN, 30 μg), streptomycin (STR, 10 μg), tetracycline (TET, 12 μg), trimethoprim-sulfamethoxazole (Sxt, 23.75/1.25 μg), and quinolone antibiotics including nalidixic acid (NAL, 30 μg), levofloxacin (LEV, 5 μg) and moxifloxacin (MOX, 5 μg). The antimicrobials were purchased

from BD (Becton Dickinson and Company, Sparks, Maryland, USA). Escherichia coli ATCC 25922 was used as the reference strain. An MDR isolate was defined as having resistance to three or more antibiotics belonging to different antibiotic classes. Pulsed-field gel electrophoresis (PFGE) The PulseNet Standardized Laboratory PFGE Protocol for Molecular Subtyping of Echerichia coli O157:H7, non-typhoidal Salmonella serotypes, and Shigella sonnei [40] was used for analysis of Montelukast Sodium the Salmonella isolates: 10 U of XbaI were used for the restriction digestion. PFGE images were analyzed by using the fingerprint analysis software BioNumerics version 4.5 (Applied Maths). A unique PFGE pattern was defined as one or two DNA bands differing between PFGE patterns of two isolates. A dendrogram was generated by the unweighted pairgroup method with arithmetic mean (UPGMA) algorithm using the Dice-predicted similarity value of two Xbal-digested PFGE patterns. Plasmid profile analysis Plasmid profiles of each isolate were determined by the Kado and Liu method [41], and plasmid size was estimated by comparison with the plasmids of two S. Choleraesuis strains: OU7085 (50 kb and 6.6 kb) and OU7526 (50 kb and 90 kb).

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