A Comparative Study of ERIC-PCR and BOX-PCR Methods for Evaluation of Genomic Polymorphism among Multidrug-Resistant Enterococcus faecium Clinical Isolates

Enterococcus faecium is a normal flora of gut microbiota. This opportunistic pathogen has attracted much attention due to its multidrug resistance and ability to survive in hostile environments. Various molecular typing methods such as pulsed-field gel electrophoresis or ribotyping have been developed for clinical and epidemiological investigation of these bacteria. However, these methods are time-consuming and labor-intensive. The present study was conducted to evaluate the discriminatory power of two common fingerprinting methods i.e. BOX-polymerase chain reaction (PCR) and enterobacterial repetitive intergenic consensus (ERIC)-PCR for E. faecium clinical isolates.

Fifty multidrug-resistant E. faecium isolates were isolated from 74 clinical specimens. The isolates were identified by specific 16S rRNA PCR. All isolates were fingerprinted using BOX-PCR and ERIC PCR. The discriminatory power and reproducibility of these two methods were also assessed.

According to the dendrogram with >60% similarity, 17 different genotypes were observed using ERIC PCR. In addition, BOX-PCR produced 22 distinct patterns at a genetic distance percentage of 60%, with sizes ranging from 278 bp to 1450 bp. The discrimination index of BOX-PCR was higher than that of ERIC-PCR.

We concluded that a combination of ERIC-PCR and BOX-PCR may be a quicker and more reliable alternative for the discrimination of E. faecium clinical isolates.