Molecular characteristics and virulence factors in methicillin-susceptible, resistant, and heterogeneous vancomycin-intermediate Staphylococcus aureus from central-southern China.
BACKGROUND
Staphylococcus aureus is a leading cause of nosocomial infections. The purpose of this study was to evaluate the prevalence of methicillin-resistant S. aureus (MRSA) and heterogeneous vancomycin-intermediate S. aureus (hVISA), and compare the antimicrobial susceptibility, molecular characteristic, and virulence factors in methicillin-susceptible S. aureus (MSSA), MRSA, and hVISA from central-southern China.


METHODS
A total of 184 S. aureus were isolated from sterile body fluids. All isolates were subjected to population analysis profiling for the identification of hVISA phenotype and polymerase chain reaction analysis for genotyping and 31 virulence genes.


RESULTS
The prevalence of MRSA isolates was 41.8% in central-southern China. Of 77 MRSA isolates, 17 (22.1%) were identified as hVISA. The most common MRSA and MSSA clones were ST239-MRSA-SCCmecIII-t030-agr-I (55.8%) and ST188-MSSA-t189-agr-I (20.6%), respectively. The frequency of carriage of pvl, hemolysins, tst, and staphylococcal enterotoxin genes among MSSA isolates was significantly higher than that for MRSA isolates (p < 0.05); 98 MSSA isolates (53.3%) carried ≥ 10 tested virulence genes simultaneously, which was significantly higher than that of MRSA isolates (33.8%; p = 0.004). The 17 hVISA isolates carried a significantly small number of virulence genes; only two hVISA isolates carried ≥ 10 tested virulence genes simultaneously, and two hVISA isolates harbored only four virulence genes. Compared with other clonal complexes (CCs), CC1 and CC398 isolates harbored a higher frequency of exfoliatin genes, CC1 and CC59 harbored a higher frequency of pvl gene, and only CC1 isolates harbored lukED.


CONCLUSIONS
The prevalence of hVISA was considerably high in central-southern China. Simultaneous carriage of multiple virulence genes was common in S. aureus isolates; the virulence genes were more diverse and frequent among MSSA isolates than among MRSA isolates. Furthermore, the distribution of some virulence genes was correlated with the different S. aureus CCs.
Department of Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Cailin
C
Liu
Department of Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Zhong-ju
ZJ
Chen
Department of Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. Electronic address: tjszyong@163.com.
Ziyong
Z
Sun
Department of Laboratory, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
Xianju
X
Feng
Department of Laboratory, Xiangya Hospital of Central South University, Changsha, China.
Mingxiang
M
Zou
Department of Laboratory, The Second Xiangya Hospital of Central South University, Changsha, China.
Wei
W
Cao
Department of Laboratory, Henan Province People's Hospital, Zhengzhou, China.
Shanmei
S
Wang
Department of Laboratory, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Ji
J
Zeng
Department of Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Yue
Y
Wang
Department of Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Mingyue
M
Sun
D002681:China / Q000453:epidemiology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D016106:Methicillin Resistance; D010641:Phenotype; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D020713:Vancomycin Resistance; D037521:Virulence Factors / Q000235:genetics*
D037521:Virulence Factors
Heterogeneous vancomycin-intermediate Staphylococcus aureus; Methicillin-resistant Staphylococcus aureus; Molecular; Staphylococcus aureus; Virulence gene