Gelatinase activity was detected by streaking all identified isolates on TSA containing 1.5% (v/v) skim milk [27]. E. faecalis MMH594 was used as a positive control and E. faecalis FA2-2 as a negative control. For detection of hemolytic activity, E. faecalis and E. faecium were streaked on Columbia agar base supplemented with 5% (v/v) fresh sterile human blood and grown for 24-48 h at 37°C. Isolates showing a complete clearance zone around the colonies indicated β-hemolysin production [27]. E. faecalis MMH594 was used as a positive
control and E. faecalis FA2-2 as a negative control. Production of aggregation substance was determined by the clumping assay [77]. E. faecalis OG1RF:pCF10 and JH2-2 were P005091 mouse used as positive and negative controls, respectively. Genotypic screening for antibiotic resistance, virulence and integrase genes Multiplex or single PCR were used to screen all identified isolates for tetracycline and erythromycin resistance genes including, tet (S), tet (M), tet (O), tet (K), tet (A), tet (C), tet (Q), tet (W)] and erm (B) and for four putative virulence determinants gelE, cylA, esp, and asa1 [78–81]. Integrase gene (int) was used for detection of the conjugative transposon family Tn 1545/Tn 916 [19, 82]. To confirm the identity of our
PCR products, one randomly Selleckchem Batimastat selected PCR product for each resistance, virulence, and transposon determinant was purified with GFX PCR DNA and Gel Band Purification Kit (Amersham Bioscience, UK) and sequences were determined
on an ABI 3700 DNA Analyzer at the K-State DNA Sequencing Facility using the same PCR primers. Sequences were analyzed for similarity to known sequences in the GenBank database using BLAST (Basic Local Alignment selleck Search Tool) [83]. Manual sequence alignment was done with CodonCode Aligner (Version 1,3,4) (CodonCode Corporation, Dedham, MA) (data not shown). Genotyping of selected isolates with pulsed-field gel electrophoresis (PFGE) PFGE protocol of Amachawadi et al. [84] was used with minor modifications. Agarose plugs were digested with 40 U of Apa I (Promega, Madison, WI) for 4 h at 37°C. The digested plugs were run on Erastin to a 1% SeaKem Gold Agarose (Lonza, Rockland, MI) gel using CHEF Mapper (Bio-Rad, Hercules, CA) with initial pulse time for 1 s and final time for 20 s at 200 V for 21 h. Cluster analysis was performed with BioNumerics software (Applied Maths, Korrijk, Belgium) using the band-based Dice correlation coefficient and the unweighted pair group mathematical average algorithm (UPGMA). Data analysis Differences in the prevalence of antibiotic resistance and virulence factors (genotype and phenotype) among enterococcal isolates from pig feces, house flies and roach feces were analyzed using chi-square analysis of contingency tables and Fisher’s exact test (α = 0.05). Species with zero prevalence of antibiotic resistance and virulence factors (genotype and phenotype) were not included in the analysis.