SAN FRANCISCO — An increase in community-acquired methicillin-resistant Staphylococcus aureus over the past 5 years was accompanied by an increase in myositis and pyomyositis in children at one hospital, reported Dr. Pia S. Pannaraj.
Until recently, infective pyomyositis primarily was a tropical disease and affected only 1 in every 300,000-400,000 U.S. hospital admissions. Published reports of acute bacterial myositis were less common than pyomyositis and mainly described disease in adults, not children. Acute bacterial myositis moves beyond distinct abscesses within the muscle to extend inflammation through one or more muscle groups.
Records at Texas Children's Hospital, Houston, for the 5-year period 2000-2004 indicated 96 cases of infective bacterial myositis in children who had no underlying condition. S. aureus caused 66 of these infections, she said at the annual meeting of the Infectious Diseases Society of America.
“It's important to know that myositis … is not as rare as people once thought. At least, we're seeing more cases of it. It correlates with the increase in Staph aureus” acquired in the community, Dr. Pannaraj of Baylor College of Medicine, Houston, said in an interview at her poster presentation.
In all, 38 (58%) of the 66 cases due to S. aureus were community-acquired methicillin-resistant S. aureus (MRSA), and 28 (42%) were due to community-acquired methicillin-sensitive S. aureus (MSSA).
The frequency of infective bacterial myositis cases increased from 10 cases in 2000 to 36 cases in 2004 at Dr. Pannaraj's institution. Most of the increase came from community-acquired MRSA. Frequencies of other isolates did not change significantly over time.
Children with muscular disease due to MRSA had a more severe course of illness than children with MSSA.