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

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pISSN 2288-0585 eISSN 2288-6850

Nasal Colonization of Serine Protease esp-Positive Staphylococcus epidermidis Affecting Staphylococcus aureus Colonization

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2021 March, Volume 24, Issue 1, pages 105-110.

https://doi.org/10.5145/ACM.2021.24.3.5

Nasal Colonization of Serine Protease esp-Positive Staphylococcus epidermidis Affecting Staphylococcus aureus Colonization

Goeun Kang, Hyun Soo Kim, Han-Sung Kim, Wonkeun Song, Jae-Seok Kim
Department of Laboratory Medicine, Hallym University College of Medicine, Seoul, Korea

Abstract

Background: Staphylococcus aureus is a common colonizer of the nasal vestibule and is found in approximately 20%–30% of healthy adults, while Staphylococcus epidermidis appears to be the most frequent colonizer in all regions of the upper respiratory tract. Esp, a serine protease of S. epidermidis, was reported to inhibit S. aureus colonization. This study was performed to examine the nasal colonization of S. aureus and S. epidermidis and the presence of esp determinants.

Methods: Nasal swab specimens from 54 patients were cultured on blood agar plates (BAP) and selective media for S. aureus (S. aureus ID, bioMerieux, France) for the isolation of S. aureus and S. epidermidis. After 48 hours of incubation of with BAP, three or four colonies suspected of being coagulase-negative staphylococci (CNS) were identified by MALDI-TOF MS (Bruker, Germany). Polymerase chain reaction (PCR) for esp was performed on all CNS isolates identified as S. epidermidis.

Results: Forty-three S. epidermidis strains were isolated from 18 (33.3%) of the 54 patients. Nine (50.0%) of the 18 patients carried S. aureus, while the other nine did not. Of the 36 S. epidermidis non-carriers, 13 (36.1%) were colonized by S. aureus. All S. epidermidis strains were confirmed by PCR to have esp determinants.

Conclusion: S. epidermidis colonization did not affect S. aureus colonization in the nasal cavity. All S. epidermidis strains harbored the esp gene. We could not find any differences in the nasal colonization rates of S. aureus according to the presence of esp-positive S. epidermidis. Further research on the characterization of S. epidermidis in Korea is needed to understand the association between S. epidermidis and S. aureus colonization.

Keywords

Colonization, esp, Serine protease, Staphylococcus aureus, Staphylococcus epidermidis