Molecular Characteristic and Virulence Gene Profiles of Community-Associated Methicillin-Resistant Staphylococcus aureus Isolates from Pediatric Patients in Shanghai, China

Abstract

Staphylococcus aureus is a globally important human pathogen, especially among children and immunocompromised patients. The emergence and spread of community-associated methicillin-resistant S. aureus (CA-MRSA) has become a serious public health problem worldwide. The aim of this study was to investigate the prevalence, molecular characteristics and virulence profiles of CA-MRSA infections from pediatric patients in a university hospital in Shanghai, China. A total of 80 CA-MRSA isolates were collected from July 2012 to December 2013 in Shanghai Children's Medical Center and analyzed by multilocus sequence typing, staphylococcus chromosomal cassette mec (SCCmec) typing, and spa typing. The detection of Panton-Valentine Leukocidin (pvl), superantigenic and exfoliative toxins, and adhesin genes was also performed. Overall, 16 distinct sequence types (STs) were identified among the 80 isolates. Among them, ST59 was found to be the most prevalent, followed by ST398 (11.3%, 9/80) and ST88 (8.8%, 7/80). SCCmec types IV and V were observed, at 60 and 40%, respectively. Thirty spa types were identified, spa t437 (23.8%) was the most predominant type. All 80 isolates exhibited carriage of at least four virulence genes. Thirty-four (42.5%, 34/80) isolates harbored ≥10 tested virulence genes. Adhesion genes were present in most of the MRSA isolates, including the following: icaA (100%), clfA (100%), sdrC (95%), and sdrE (63.8%). The prevalence of pvl gene was 20%, and multidrug resistance was observed in 36% of all strains. In addition, ST59-MRSA-IV with t437 accounted for 21.3% of occurrences, making it the most prevalent clone. Isolates that were carriers of toxin genes, and hla (100%) and hlg (87.5%) were the most frequent. In conclusion, simultaneous carriage of multiple virulence genes and genetically considerable diversity were very common among CA-MRSA from pediatric patients in Shanghai. ST59-MRSA-IV with t437 was still the most predominant type. The combination of virulence gene profiles and antibiotic resistance may help ST59 to be successfully spread among children.

Molecular Characterizations, Virulence Determinants and Antimicrobial Resistance Profiles of Methicillin-Resistant Staphylococcus aureus (MRSA) in the North of Iran

“…Historically, the expression level of the most virulence factors of S. aureus is regulated by agr locus [3]. In agreement with our previous reports [14,53], the most common MRSA isolates belonged to agr I (64.86%), followed by agr type III (24.3%).…”

“…However, low gentamycin resistance rates in Chinese and Iranian MRSA isolates have been reported [3,15,47]. All of the MRSA isolates in the present study were MDR which is in relative line with previous reports from Iran [2,14] and Taiwan [38].…”

“…Methicillin-resistant Staphylococcus aureus (MRSA) is known to be resistant to various antibiotics and produces many virulence factors, which contribute to high treatment failure [1]. Hence, MRSA is one of the main causes of hospital and community-acquired infections worldwide (HA-MRSA, CA-MRSA) [1][2][3]. MRSA causes infections ranging from skin and soft tissue to deep-seated and severe life-threatening ones (endocarditis, osteomyelitis, necrotizing pneumonia, meningitis, and toxic shock syndrome) [4][5][6][7].…”

Molecular characteristics and virulence gene profiles of Staphylococcus aureus isolates in Hainan, China

“…The virulence factors of S. aureus play an important role during pathogenesis [37,38]. Similar to the majority of studies in mainland China [8,39], almost all strains in our study were positive for clfA and hla, confirming that these were the most common virulence factors in S. aureus, and there was no regional difference in their distribution. Notably, the positive rates of eta and pvl were 57.3% and 47.6%, much higher than those in mainland China [10,15,18].…”

Multiresistant ST59-SCCmec IV-t437 clone with strong biofilm-forming capacity was identified predominantly in MRSA isolated from Chinese children

“…Although many studies have reported the phenotypic and genotypic basis for biofilm production in SA clinical strains isolated from different infectious diseases and different countries [ 8 – 10 ], little is known regarding the biofilm formation ability of SA clinical strains isolated from Chinese, especially children. According to our knowledge, only the prevalence of adhesion genes was ever reported among SA strains isolated from children in china, but these studies didn’t assess the biofilm formation ability of bacteria [ 11 , 12 ].…”