Molecular characterization and antimicrobial resistance of nine strains of CA-MRSA isolated from clinical inpatients

doi:10.16150/j.1671-2870.2021.01.010

Abstract

Abstract:

Objective: To investigate the molecular characterization and antimicrobial resistance of CA-MRSA(community-associated methicillin-resistant Staphylococcus aureus) strains isolated from clinical inpatientsto provide evidence for prevention and treatment of CA-MRSA infections. Methods: Isolates of S. aureus from hospitalized patients were collected within 24 h after admission from April 2014 to Dec. 2015, and mecA gene was detected to distinguish MRSA from MSSA (methicillin-sensitive Staphylococcus aureus). Genotypic CA-MRSA strains carrying SCC mec Ⅳ/Ⅴ were obtainedfor further analysis of molecular epidemiologic characters by spa-typing and MLST（multilocus -sequence typing）. Based on the CLSI (Clinical and Laboratory Standards Istitute) guidelines, disk diffusion method was used to test drug susceptibility of CA-MRSA strains. Moreover, the presence of pvl virulence gene was detected by PCR. Results: A total of 147 strains of S. aureus including 58 MRSA strains were collected from hospitalized patients. By SCCmec typing, 9 CA-MRSA strains (SCCmec Ⅳ 3; SCCmec Ⅴ 6) were detected. All CA-MRSA strains developed resistance against different non-β-lactams, among which 8 strains developed drug-resistanceagainst aminoglycosides (mainly kanamycin) and 8 strains developed drug-resistance against erythromycin and clindamycin mediated by erm(B) mainly. Molecular typing revealed that the main CA-MRSA clone was t437-ST59, and other clones were t034-ST804, t127-ST1, t008-ST8 and t437-ST338. In addition, 5 out of 9 CA-MRSA strains were pvl gene positive. Conclusions: More pathogenic CA-MRSA strains are invading healthcare-associated settings and developing more resistance against non-β-lactams, indicating that the CA-MRSA should be closely monitored in hospitals.

Key words: Community-associated methicillin resistant Staphylococcus aureus, Molecular characterization, Antimicro-bial resistance

CLC Number:

R515

WANG Yuanxia, YAO Lifeng, ZHENG Qiaoping, CHEN Xu. Molecular characterization and antimicrobial resistance of nine strains of CA-MRSA isolated from clinical inpatients[J]. Journal of Diagnostics Concepts & Practice, 2021, 20(01): 66-70.

Figures/Tables 3

References 17

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SCCmec类型	ccr基因复合物	mec基因复合物
Ⅰ	1	B
Ⅱ	2	A
Ⅲ	3	A
Ⅳ	2	B
Ⅴ	5	C2

引物名称	引物序列	基因片段（bp）
mecA-1	5′-TCCAGATTACAACTTCACCAGG-3′	162
mecA-2	5′-CCACTTCATATCTTGTAACG-3′
erm(A)-1	5′-GTTCAAGAACAATCAATACAGAG-3′	421
erm(A)-2	5′-GGATCAGGAAAAGGACATTT TAC-3′
erm(B)-1	5′-CCGTTTACGAAATTGGAACAGGTAAAGGGC-3′	359
erm(B)-2	5′-GAATCGAGACTTGAGTGTGC-3′
erm(C)-1	5′-GCTAATATTGTTTAAATCGTCAATTCC-3′	572
erm(C)-2	5′-GGATCAGGAAAAGGACATTTTAC-3′
pvl-1	5′-ATCATTAGGTAAAATGTCTGGACATGATCCA-3′	433
pvl-2	5′-GCATCAASTGTATTGGATACCAAAAGC-3′

菌株	SCCmec	SPA型别	ST型别	耐药药物	D-试验	耐药基因	pvl基因
1	Ⅴ	t034	804	E	iMLS_B	erm(C)	阴性
2	Ⅳ	t127	1	K、TOB	-	-	阴性
3	Ⅴ	t437	59	K、E、CC	cMLS_B	erm(B)	阳性
4	Ⅴ	t437	59	K、E、CC	cMLS_B	erm(B)	阳性
5	Ⅳ	t437	59	K、E、CC	cMLS_B	erm(B)	阴性
6	Ⅴ	t437	59	K、E、CC	cMLS_B	erm(B)	阳性
7	Ⅳ	t008	8	CN、K、TOB、E	iMLS_B	erm(C)	阴性
8	Ⅴ	t437	59	K、E	cMLS_B	erm(B)	阳性
9	Ⅴ	t437	338	K、E、CC	cMLS_B	erm(B)	阳性