9) 100/89.7 100/50 80.0/60.0 tet (S) + erm (B) 1 (1.7) 1 (3.4) 1 (2.8) 100/100 100/100 100/100 tet (O) + erm (B) 0 1 (3.4) 1 (2.8) 100/100 100/100 tet (M) + tet (O) + tet (S) + erm (B) 1 (1.7) 0 1 (2.8) 100/100 – 100/100 Isolates Sepantronium mouse with no detected tet and erm (B) determinants 6 (10.0) 7 (24.1) 8 (22.2) 66.6/66.6 0.0/50.0 25.0/37.5 Multiple resistance determinants, specifically tet (M) and erm (B), were detected in E. faecalis, E. faecium, E. hirae, and E. casseliflavus (Tables 1, 2, Additional files 1-2). In general, the levels
of prevalence of multiple resistance determinants tet (M) and erm (B) were similar and no significant differences were observed in E. faecalis (P = 0.4151), E. faecium (P = 0.0864), E. hirae (P = 0.5873) and E. casseliflavus (P = 0.5760) isolated from the digestive tract of house flies and feces of German cockroaches and pigs (Tables 1, 2, Additional files 1-2). Since most of the tetracycline resistant isolates were also resistant to erythromycin, and the tet (M) gene is frequently linked with the erm (B) gene on the highly mobile Linsitinib cell line conjugative transposon Tn 1545, tests for the detection of int genes were also performed for the presence of conjugative transposons of the Tn 1545/Tn 916 family. The results revealed that
the Tn 1545/Tn 916 conjugative transposon family was found in 219/639 (34.3%) identified isolates from all samples. The Tn 1545/Tn 916 family determinant was commonly detected in E. faecalis followed by E. hirae, E. casseliflavus, and E. faecium (Additional file 3). The most common E. faecalis genotypes based on a combination of antibiotic XMU-MP-1 resistance and Tn 1545/Tn 916 family determinants were tet (M) plus erm (B) plus Tn 916/1545 followed by tet (M) plus Tn 916/1545 (Additional
file 3). In addition, many (23.3%) E. faecalis isolates from pig feces also carried frequently resistance determinants including tet nearly (M), tet (K) and erm (B) in combination with the Tn 1545/Tn 916 family (Additional file 3). Prevalence and diversity of virulence factors by phenotype and genotype The overall prevalence of putative virulence factors (gelatinase, haemolysin and aggregation substance production) for all identified isolates is listed in Figure 4. Gelatinase production on skimmed milk agar was the most common virulence factor among all identified isolates, with significantly higher incidence in E. faecalis than in E. casseliflavus, E. faecium, and E. hirae (Figure 4). No significant differences were detected in prevalence of gelatinase production among E. faecalis and E. faecium isolated from the digestive tract of house flies and feces of German cockroaches and pigs (Figure 4). Figure 4 Phenotypic virulence factor (% prevalence) of (A) E. faecalis , (B) E. faecium , (C) E. hirae and (D) E. casseliflavus isolated from pig feces, German cockroach feces, and the digestive tract of house flies collected on two swine farms. The prevalence of β-hemolysis on human blood agar in E. faecalis was higher than that observed in E.