Isolation of VanA-type vancomycin-resistant Enterococcus strains from domestic poultry products with enrichment by incubation in buffered peptone water at 42 degrees C

Abstract

Eight VanA-type enterococcal strains were isolated from 8 of 171 domestic poultry products by using enrichment by incubation in buffered peptone water at 35 degrees C and 42 degrees C. The pulsed-field gel electrophoresis patterns of all six VanA-type Enterococcus faecalis isolates were nearly indistinguishable, indicating the presence of a specific clone in Japan.

FIG. 1.

DNA fingerprinting of VanA-type VRE (E. faecalis and E. faecium strains) isolated from retail domestic poultry samples. Isolated genomic DNA of each isolate was digested with SmaI and subjected to PFGE. Lane 1, E. faecalis Ha8; lane 2, E. faecalis Ha16; lane 3, E. faecalis Ha36; lane 4, E. faecalis Ha55; lane 5, E. faecalis Ha58; lane 6, E. faecalis Ha61; lane 7, E. faecium Ha20; lane 8, E. faecium Ha26; lanes M, XbaI-digested PFGE patterns of DNA size standard Salmonella enterica serovar Braenderup H9812. Numbers to the left of the gel image indicate the molecular size in kilobase pairs.

FIG. 2.

Growth curves of E. faecalis Ha8 (A) and E. faecium Ha20 (B) cultured in BHI broth incubated at either 35°C (▪) or 42°C (○). Results obtained from three independent experiments are presented as means ± standard deviations.

FIG. 3.

Growth curves of background microflora and suspected enterococcal strains in three different poultry samples cultured in BPW incubated at either 35°C or 42°C. ▴, background microflora; □, suspected enterococcal strains. Solid lines show the data for incubation at 35°C, and dotted lines show those for incubation at 42°C.