Journal Article

Antimicrobial susceptibility patterns and macrolide resistance genes of viridans group streptococci from blood cultures in Korea

Young Uh, Dong Hoon Shin, In Ho Jang, Gyu Yel Hwang, Mi Kyung Lee, Kap Jun Yoon and Hyo Youl Kim

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 53, issue 6, pages 1095-1097
Published in print June 2004 | ISSN: 0305-7453
Published online June 2004 | e-ISSN: 1460-2091 | DOI: https://dx.doi.org/10.1093/jac/dkh219
Antimicrobial susceptibility patterns and macrolide resistance genes of viridans group streptococci from blood cultures in Korea

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Objectives: Our aim was to study the antimicrobial susceptibilities and macrolide resistance mechanisms of viridans group streptococci (VGS) in a Korean tertiary hospital.

Methods: MICs of five antimicrobials were determined for 106 VGS isolated from blood cultures. The macrolide resistance mechanisms of erythromycin non-susceptible isolates were studied by the double-disc test and PCR.

Results: In all, 42.4% of the isolates were susceptible to penicillin. Nine of 61 penicillin non-susceptible isolates were fully resistant (MIC ≥ 4 mg/L). Rates of non-susceptibility to erythromycin, clindamycin and ceftriaxone were 33.9%, 17.9% and 9.4%, respectively. Twenty-two (61.1%) of 36 erythromycin non-susceptible isolates expressed constitutive resistance to macrolide–lincosamide–streptogramin B antibiotics (a constitutive MLSB phenotype); 13 isolates (36.1%) expressed an M phenotype; and one isolate, a Streptococcus bovis isolate, had an inducible MLSB resistance phenotype. erm(B) was found in isolates with constitutive/inducible MLSB phenotypes, and mef(A) in isolates with the M phenotype. In three isolates (two isolates with a constitutive MLSB phenotype and in one isolate with the M phenotype), none of erm(A), erm(B), erm(C) or mef(A) was detected by PCR.

Conclusions: Penicillin non-susceptible VGS were more resistant to erythromycin, clindamycin and ceftriaxone than were penicillin-susceptible isolates. A constitutive MLSB phenotype associated with erm(B) was the predominant mechanism of macrolide resistance among erythromycin non-susceptible isolates from this Korean hospital.

Keywords: Keywords: α-haemolytic streptococci, erythromycin resistance, MLSB phenotype, erm(B), mef(A)

Journal Article.  1456 words. 

Subjects: Medical Oncology ; Critical Care

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