OBJECTIVE: To study the clinical and molecular characteristics of 
methicillin-resistant Staphylococcus aureus (MRSA) infection in children.
METHOD: A total of 37 MRSA strains were isolated from hospitalized patients in 
Children's Hospital of Fudan University from March 2009 to November 2011. The 
clinical characteristics were investigated by a cohort study. Furthermore, the 
mecA, Panton-Valentine leucocidin (PVL) genes were detected by polymerase chain 
reaction (PCR), and the genotypes of SCCmec were determined by multiplex PCR.
RESULT: (1) Among the 37 MRSA isolates, infections with 21 were acquired from 
hospital (HA-MRSA), and 16 isolates were acquired from community (CA-MRSA). (2) 
In the study, MRSA frequently caused respiratory tract infection, and most of 
the strains were isolated from intensive care unit (ICU). (3) CA-MRSA was most 
frequently associated with skin and soft tissue infections (SSTI), suppurative 
tonsillitis, even pneumonia and septicemia. HA-MRSA infection was more 
aggressive, most frequently associated with pneumonia, septicemia, and central 
nervous system (CNS) infections, such as meningitis. In children with fever 
caused by HA-MRSA or CA-MRSA infection, HA-MRSA showed a longer duration of 
fever, for 10.5 days. C-reactive protein (CRP) level caused by HA-MRSA (63.00 
mg/L) was higher than CA-MRSA (9.50 mg/L) , and there were statistically 
significant differences between the groups (t = 2.5670, P < 0.05). However, 
there were no statistically significant differences between the groups in white 
blood cell count (WBC) or procalcitonin (PCT) level. (4) Among 37 MRSA isolates, 
the whole isolates were mecA gene positive (100%). SCCmec genotyping results 
showed that the most frequent SCCmec types were type III, 17 isolates, the 
others including type IV 8 isolates, type II1 isolates, nontypable 11 isolates, 
type I and type V were not found in this group. Therein, among 21 HA-MRSA 
isolates, SCCmec III was the most common, 15 isolates, type IV 1 isolates, 
nontypable 5 isolates; among 16 CA-MRSA isolates, SCCmec type IV was the most 
common, 7 isolates, type III 2 isolates, type II 1 isolate, nontypable 6 
isolates. (5) Among the 37 MRSA isolates, 28 were PVL gene positive; and among 
21 HA-MRSA isolates, 17 were PVL gene positive; Among 16 CA-MRSA isolates, 11 
were PVL gene positive; There were no statistically significant differences 
between the groups (χ(2) = 0.735, P > 0.05) .
CONCLUSION: Compared with CA-MRSA, HA-MRSA infection was more aggressive, and 
induced higher C reactive protein; the dominant epidemic strains of CA-MRSA was 
SCCmec type IV, and HA-MRSA was SCCmec type III; the positive rate of PVL gene 
was high.