Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology

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pISSN 2288-0585 eISSN 2288-6850

Distributions of Macrolide-Lincosamide-Streptogramin B Resistance Phenotypes in Clinical Isolates of Staphylococi

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2008 December Volume 11, Issue 2, pages 78-83.


https://doi.org/10.5145/ACM.2008.11.2.78

Distributions of Macrolide-Lincosamide-Streptogramin B Resistance Phenotypes in Clinical Isolates of Staphylococi

Young Uh1, Gyu Yul Hwang1, Ih Ho Jang1, Ohgun Kwon1, Kap Jun Yoon1, Hyo Youl Kim2
Departments of 1Laboratory Medicine and 2Infectious Diseases, Yonsei University Wonju College of Medicine, Wonju, Korea

Abstract

Background: Increased resistance rates to macrolide-lincosamide-streptogramin B (MLSB) antibiotics among clinical isolates of staphylococci are considered as a consequence of an expanded use of these antibiotics in the treatment of Gram-positive infections. The proportion of MLSB resistance phenotypes of staphylococci is quite different by geographical variations and study periods. The aim of the present study was to determine the distribution of MLSB resistance phenotypes among clinical isolates of staphylococci in a university hospital.

Methods: The MLSB resistance phenotypes of clinical isolates of staphylococci were investigated by the double-disk diffusion test using erythromycin and clindamycin disks.

Results: Of 7,916 isolates, 55.7% exhibited a constitutive resistance phenotype (cMLSB) whereas 8.1% expressed an inducible resistance phenotype (iMLSB). Among 3,419 coagulase-negative staphylococci (CNS), 32.6% and 10.0% exhibited cMLSB and iMLSB resistance phenotypes, respectively. Of 4,497 Staphylococcus aureus isolates, 73.1% and 6.8% were cMLSB and iMLSB resistance phenotypes, respectively. cMLSB was detected among 90.2% of methicillin-resistant S. aureus (MRSA), 46.5% of methicillin-resistant CNS (MRCNS), 3.2% of methicillin-susceptible CNS (MSCNS), and 2.2% of methicillin-susceptible S. aureus (MSSA). iMLSB was detected among 16.5% of MSSA, 11.5% of MRCNS, 6.7% of MSCNS, and 4.4% of MRSA.

Conclusion: MLSBresistance was more prevalent among S. aureus isolates than CNS strains. Although cMLSB was the most frequently detected resistance phenotype among the total staphylococcal isolates, methicillin-susceptible strains exhibited somewhat higher iMLSB resistance rates compared with methicillin-resistant strains. (Korean J Clin Microbiol 2008; 11:78-83)

Keywords

Staphylococci, Staphylococcus aureus, MLSB resistance, Constitutive, Inducible