ABSTRACT
OBJECTIVE: Staphylococcus aureus can cause sinusitis in children. The predominant MRSA clone in the United States, USA300, has been associated with skin and soft tissue as well as invasive diseases. USA300 has increased among CA methicillin-susceptible S. aureus (CA-MSSA) isolates. We describe the clinical characteristics of pediatric patients with S. aureus cultured from sinus specimens, treated at Texas Children's Hospital (TCH), and characterized their isolates by molecular methods. METHODS: This was a retrospective study of children with endoscopic sinus surgery (ESS) cultures positive for S. aureus between 01/2005 and 12/2008 at TCH. Medical records were reviewed and associated S. aureus isolates were characterized by pulsed field gel electrophoresis (PFGE). Data were analyzed by Mann-Whitney U, Chi-square, Fisher's exact test, and Chi-square for trend. RESULTS: We identified 56 patients with S. aureus sinus infections; 12 (21%) were MRSA. Seven of 12 (58%) MRSA vs. 5/44 (11%) MSSA were USA300 (p<0.01). All MRSA isolates were non-susceptible to erythromycin compared to 30% of MSSA (p<0.01); 75% of the USA300 strains were non-susceptible to erythromycin compared to 36% of the non-USA300 strains (p<0.04). Co-pathogens were isolated from 77% (43/56) of the patient specimens. Both MRSA and USA300 isolates were associated with Haemophilus influenzae co-isolation (p<0.05). Patients with USA300 strains were significantly younger (p=0.02) and more likely to experience snoring as a symptom associated with their sinusitis (p=0.03) than those infected with non-USA300 strains. Children with MRSA (4/12) tended to have a greater recurrence rate than children with MSSA isolates (5/44) (p=0.09). No significant differences were observed between groups for fever or complications such as neck cellulitis, nasal abscess, meningitis, subdural empyema, and orbital cellulitis. CONCLUSION: MSSA was more commonly isolated than MRSA from sinus cultures of children who underwent ESS at TCH. The majority of ESS cultures positive for S. aureus, were mixed with other respiratory pathogens, principally H. influenzae. USA300 was the major clone among the MRSA sinusitis isolates, but was not associated with more complications than other S. aureus isolates.
