Isolation and antibiotic susceptibility of enterococcus spp. from fermented soy paste

Abstract

To evaluate the antibiotic risk of Enterococcus in fermented soy paste, Enterococcus spp. were isolated and identified from 31 Cheongkukjang and 17 Doenjang samples. Exactly 123 Enterococcus spp., 119 from Cheongkukjang and four from Doenjang, were ultimately isolated. The most frequently collected Enterococcus isolates in Cheongkukjang were 69 strains of E. faecium and 20 strains of E. faecalis. All four Enterococcus spp. From Deonjang were identified as E. faecium. All isolates were sensitive to ampicillin, chloramphenicol, penicillin, and tetracycline. However, they showed broad spectra from sensitivity to resistance to erythromycin, ripampin, and streptomycin. Vancomycin minimum inhibition concentration (MIC) of Enterococcus spp. from Cheongkukjang ranged from 0.25 to 8 μg/mL. Almost all strains were sensitive to vancomycin, but eight strains showed intermediate resistance to vancomycin. Seventeen strains showing the highest MIC of 8 μg/mL among all isolates were evenly distributed among E. faecalis, E. faecium, E. gallinarum, and E. casselifalvus, in which the strong resistant genes of vanA and vanB for vancomycin were not detected. Overall antibiotic resistance of Enterococcus isolates was relatively low and particularly low vancomycin resistance was similar to those of Enterococcus isolates obtained from other foods. Therefore, the antibiotics resistance of Enterococcus and especially vancomycin-resistant Enterococcus spp. from Cheongkukjang and Doenjang is not hazardous.