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Molecular Characterization of Staphylococcus aureus Isolates From Children With Periorbital or Orbital Cellulitis
Catherine E Foster1, Elizabeth Yarotsky2, Edward O Mason1
1Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston.
Insights
Pediatric periorbital and orbital cellulitis are often caused by methicillin-resistant Staphylococcus aureus (MRSA). Antibiotic treatment should cover MRSA, and Panton-Valentine leukocidin (PVL) may be a key virulence factor.
Area of Science:
- Pediatric infectious diseases
- Ophthalmology
- Microbiology
Background:
- Periorbital and orbital cellulitis are common pediatric conditions causing significant morbidity.
- Staphylococcus aureus is a frequent pathogen in these infections.
Purpose of the Study:
- To define clinical features of pediatric periorbital/orbital cellulitis caused by Staphylococcus aureus.
- To characterize S. aureus isolates, including MRSA and PVL-producing strains.
Main Methods:
- Retrospective analysis of demographic and clinical data from 85 pediatric patients.
- Genotyping of S. aureus isolates using pulsed-field gel electrophoresis.
- Detection of Panton-Valentine leukocidin (pvl) genes via quantitative PCR.
Main Results:
- Most infections (67%) were caused by methicillin-resistant S. aureus (MRSA), predominantly USA300 strains (78%).
- A high prevalence of pvl-positive isolates (85%) was observed.
- Orbital cellulitis patients required longer hospitalization (median 12 days) and antibiotic treatment (median 21 days) compared to periorbital cases.
Conclusions:
- MRSA is the primary cause of pediatric periorbital and orbital cellulitis at this institution.
- Empirical antibiotic therapy should include MRSA coverage.
- Panton-Valentine leukocidin (PVL) may play a significant role in virulence; S. aureus infections are associated with sinusitis.
Background:
Periorbital and orbital cellulitis cause significant pediatric morbidity. Here, we define the clinical features of and characterize isolates from children with periorbital or orbital cellulitis caused by Staphylococcus aureus at Texas Children's Hospital in Houston.
Methods:
Patients were identified from a prospective S aureus study database from January 2002 to July 2015. Demographic and clinical data were collected retrospectively. Isolates were genotyped by pulsed-field gel electrophoresis, and Panton-Valentine leukocidin (lukSF-PV [pvl]) genes were detected by quantitative polymerase chain reaction. Data were analyzed with the Fisher exact or Wilcoxon rank-sum test.
Results:
Eighty-five patients with periorbital (n = 58) or orbital (n = 27) cellulitis were identified. We found 57 (67%) methicillin-resistant S aureus (MRSA) isolates, 72 (85%) pvl-positive (pvl+) isolates, and 66 (78%) USA300 isolates. No differences in clinical characteristics were found when we compared MRSA to methicillin-susceptible (MSSA) infections or USA300 to non-USA300 infections. Patients with orbital cellulitis were hospitalized a median of 12 days (range, 2-28 days) and received antibiotics for 21 days (range, 10-32 days). Twelve (44%) patients with orbital cellulitis received steroids. Steroid treatment did not affect the length of hospitalization or duration of antibiotic treatment. Six (7%) patients with orbital cellulitis were bacteremic. Patients with periorbital cellulitis were hospitalized for a median of 3 days (range, 0-17 days) and received antibiotics for 11 days (range, 7-32 days). According to computed tomography (CT), 19 (70%) patients with orbital cellulitis and 11 (41%) with periorbital cellulitis had sinusitis.
Conclusions:
The majority of periorbital and orbital S aureus infections at Texas Children's Hospital were caused by MRSA, and no change was observed over time. Empirical antibiotic treatment should include coverage for MRSA. PVL might be an important virulence factor in these presentations. S aureus is associated with sinusitis and its complications.
