Ann Lab Med.  2016 May;36(3):250-254. 10.3343/alm.2016.36.3.250.

Antimicrobial Resistance and Molecular Characteristics of Nasal Staphylococcus aureus Isolates From Newly Admitted Inpatients

• Chen X
• Sun K
• Dong D
• Luo Q
• Peng Y
• Chen F

• KMID: 2373535
• DOI: http://doi.org/10.3343/alm.2016.36.3.250

Abstract

Staphylococcus aureus, or methicillin-resistant S. aureus (MRSA), is a significant pathogen in both nosocomial and community infections. Community-associated MRSA (CA-MRSA) strains tend to be multi-drug resistant and to invade hospital settings. This study aimed to assess the antimicrobial resistance and molecular characteristicsof nasal S. aureus among newlyadmitted inpatients.In the present study, 66 S. aureus isolates, including 10 healthcare-associated MRSA (HA-MRSA), 8 CA-MRSA, and 48 methicillin-sensitive S. aureus (MSSA) strains, were found in the nasal cavities of 62 patients by screening 292 newlyadmitted patients. Antimicrobial resistance and molecular characteristics of these isolates, including spa-type, sequence type (ST) and SCCmec type, were investigated. All isolates were sensitive to linezolid, teicoplanin, and quinupristin/dalfopristin, but high levels of resistance to penicillin and erythromycin were detected. According to D-test and erm gene detection results, the cMLSB and iMLSB phenotypes were detected in 24 and 16 isolates, respectively. All 10 HA-MRSA strains displayed the cMLSB phenotypemediated by ermA or ermA/ermC, while the cMLSB CA-MRSA and MSSA strains carried the ermB gene. Molecular characterization revealedall 10 HA-MRSA strains were derived from the ST239-SCCmec III clone, and four out of eight CA-MRSA strains were t437-ST59-SCCmec V. The results suggest that patients play an indispensable role in transmitting epidemic CA-MRSA and HA-MRSA strains.

Keyword

Staphylococcus aureus; CA-MRSA; Nasal carriage; Antimicrobial resistance; Molecular characteristics

MeSH Terms

Anti-Bacterial Agents/*pharmacology
Bacterial Proteins/genetics
Drug Resistance, Multiple, Bacterial/genetics
Humans
Inpatients
Methicillin-Resistant Staphylococcus aureus/*drug effects/genetics/isolation & purification
Methyltransferases/genetics
Microbial Sensitivity Tests
Nasal Cavity/*microbiology
Staphylococcal Infections/diagnosis/microbiology
Staphylococcus aureus/*drug effects/genetics/isolation & purification
Anti-Bacterial Agents
Bacterial Proteins
Methyltransferases

Reference

1. Gosbell IB, van Hal SJ. Staphylococcus aureus colonisation: some questions answered. Lancet Infect Dis. 2013; 13:380–381. PMID: 23473662.

2. Wertheim HF, Melles DC, Vos MC, van Leeuwen W, van Belkum A, Verbrugh HA, et al. The role of nasal carriage in Staphylococcus aureus infections. Lancet Infect Dis. 2005; 5:751–762. PMID: 16310147.

3. Ma XX, Sun DD, Wang S, Wang ML, Li M, Shang H, et al. Nasal carriage of methicillin-resistant Staphylococcus aureus among preclinical medical students: epidemiologic and molecular characteristics of methicillin-resistant S. aureus clones. Diagn Microbiol Infect Dis. 2011; 70:22–30. PMID: 21513841.

4. Qu F, Cui E, Guo T, Li H, Chen S, Liu L, et al. Nasal colonization of and clonal transmission of methicillin-susceptible Staphylococcus aureus among Chinese military volunteers. J Clin Microbiol. 2010; 48:64–69. PMID: 19889899.

5. Li M, Du X, Villaruz AE, Diep BA, Wang D, Song Y, et al. MRSA epidemic linked to a quickly spreading colonization and virulence determinant. Nat Med. 2012; 18:816–819. PMID: 22522561.

6. Chuang YY, Huang YC. Molecular epidemiology of community-associated meticillin-resistant Staphylococcus aureus in Asia. Lancet Infect Dis. 2013; 13:698–708. PMID: 23827369.

7. Chen X, Yang HH, Huangfu YC, Wang WK, Liu Y, Ni YX, et al. Molecular epidemiologic analysis of Staphylococcus aureus isolated from four burn centers. Burns. 2012; 38:738–742. PMID: 22360963.

8. Kateete DP, Kimani CN, Katabazi FA, Okeng A, Okee MS, Nanteza A, et al. Identification of Staphylococcus aureus: DNase and Mannitol salt agar improve the efficiency of the tube coagulase test. Ann Clin Microbiol Antimicrob. 2010; 9:23. PMID: 20707914.

9. CLSI. Performance standards for antimicrobial susceptibility testing. In : Twenty-fifth Informational supplement, CLSI document M100-S25; Wayne, PA. Clinical and Laboratory Standards Institute;2015.

10. Lina G, Quaglia A, Reverdy ME, Leclercq R, Vandenesch F, Etienne J. Distribution of genes encoding resistance to macrolides, lincosamides, and streptogramins among staphylococci. Antimicrob Agents Chemother. 1999; 43:1062–1066. PMID: 10223914.

11. Liu Q, Han L, Li B, Sun J, Ni Y. Virulence characteristic and MLST-agr genetic background of high-level mupirocin-resistant, MRSA isolates from Shanghai and Wenzhou, China. PLoS One. 2012; 7:e37005. PMID: 22623969.

12. Enright MC, Day NP, Davies CE, Peacock SJ, Spratt BG. Multilocus sequence typing for characterization of methicillin-resistant and methicillin-susceptible clones of Staphylococcus aureus. J Clin Microbiol. 2000; 38:1008–1015. PMID: 10698988.

13. Chen X, Wang WK, Han LZ, Liu Y, Zhang H, Tang J, et al. Epidemiological and genetic diversity of Staphylococcus aureus causing bloodstream infection in Shanghai, 2009-2011. PLoS One. 2013; 8:e72811. PMID: 24039803.

14. Forster AJ, Oake N, Roth V, Suh KN, Majewski J, Leeder C, et al. Patient-level factors associated with methicillin-resistant Staphylococcus aureus carriage at hospital admission: a systematic review. Am J Infect Control. 2013; 41:214–220. PMID: 22999773.

15. Farley JE, Ross T, Krall J, Hayat M, Caston-Gaa A, Perl T, et al. Prevalence, risk factors, and molecular epidemiology of methicillin-resistant Staphylococcus aureus nasal and axillary colonization among psychiatric patients on admission to an academic medical center. Am J Infect Control. 2013; 41:199–203. PMID: 22999771.

16. Kouyos R, Klein E, Grenfell B. Hospital-community interactions foster coexistence between methicillin-resistant strains of Staphylococcus aureus. PLoS Pathog. 2013; 9:e1003134. PMID: 23468619.