Comparison of ViTEK 2, MALDI-TOF and Partial Sequencing of 16S rRNA Gene in Identification of Brevibacterium Species with its Antibiotic Susceptibility Pattern

Abstract

Background - Brevibacterium species were formerly viewed as apathogenic, however, recent reported cases of infectious states caused by Brevibacterium sp. have renewed interests in the genus as infectious agents. However, several authors have reported difficulties in identification of different species in the genus and resistance to some antibiotics.
Objectives – This study is therefore designed to compare accuracies of 3 methods for identification of Brevibacterium spp. and their antibiotic susceptibility pattern.
Methods – Ten Brevibacterium spp. were presumptively identified from staphylococci collections due to their characteristic cheesy smell. The selected isolates were identified by MALDI TOF, Vitek 2 identification system and partial sequencing of 16S rRNA gene by standard procedures. The antibiotic susceptibility was determined by disc diffusion method.
Results - Vitek 2 identification system misidentified all the organisms while MALDI TOF identification system correctly identified the Brevibacterium strains to the genus level but with scores less than 1.7 for all tested strains. 16S rRNA identification identified the 10 strains as 3 species: 5 B. epidermidis, 3 B. iodinum and 2 B. oceani. All the strains were susceptible to Vancomycin, Linezolid and Rifampicin while they were all resistant to Penicillin, Fusidic acid, and Trimethoprim. Brevibacterium epidermidis were generally resistant to Erythromycin and Clindamycin while B. iodinum and B. oceani were susceptible.
Conclusion - 16S rRNA identification is the only method that could correctly identified Brevibacterium sp to the species level in this study. High susceptibility was shown by all tested strains to Vancomycin, Linezolid and Rifampicin

Keywords – Brevibacterium, Identification, Antibiotic susceptibility