engleski

Comparison of species-specific multiplex PCR and API 20 Strep for the identification of veterinary clinical Enterococcus isolates

Bacteria of the genus Enterococcus are intrinsically resistant to several commonly used antimicrobial drugs. In addition, enterococci have a great ability to acquire new resistance mechanisms, which can lead to multidrug-resistant isolates. The species of the greatest clinical importance are Enterococcus faecium and Enterococcus faecalis. Because of the naturally occurring differences in the susceptibility of these species, rapid and accurate identification among enterococci isolates is very important for choosing appropriate antimicrobial therapy. Since the identification by routine standard methods, including commercially standardized system such as API (bioMérieux, France), is time consuming and not always reliable, nowadays identification by molecular methods is recommended. The purpose of this investigation was to compare the performance of multiplex PCR and API 20 STREP in determining Enterococcus faecium and Enterococcus faecalis species among enterococcal isolates from animals. In this study, the enterococci isolates from clinical samples of cats and dogs in Croatia were investigated. A total of 40 isolates were tested for specific ddlE. faecalis and ddlE. faecium genes by multiplex PCR assay. API 20 STREP (bioMérieux, France) was performed for the same isolates. Enterococcus faecalis ATCC 29212 and Enterococcus faecium ATCC 6057 were included as reference strains. With the multiplex PCR assay, 32 isolates were identified as Enterococcus faecalis, and 8 isolates as Enterococcus faecium. API 20 STREP identified 28 isolates as Enterococcus faecalis, 11 isolates as Enterococcus faecium and one isolate as Enterococcus avium. Overall, among 40 isolates, 35 (87 %) were equally identified as Enterococcus faecalis or Enterococcus faecium with both API 20 STREP and multiplex PCR. For five isolates (13 %), API 20 STREP did not result in correct identification. Four isolates were identified as Enterococcus faecium by API 20 STREP, but the PCR identified them as Enterococcus faecalis. Isolate identified as Enterococcus avium was recognized as Enterococcus faecium with the multiplex PCR assay. Considering the differences in innate susceptibility between two investigated enterococcal species, correct identification is crucial for choosing appropriate antimicrobial therapy. The use of species-specific PCR, as a method for the identification, is strongly recommended, especially in complicated infections caused by multidrug-resistant enterococci.

Enterococcus ; API ; multiplex PCR

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