19A emerges as predominant serotype in cases of pneumococcal mastoiditis

August 2008

Observed increases in the occurrences of subperiosteal abscesses and performed mastoidectomy were observed at a greater rate among children with mastoiditis caused by serotype 19A Streptococcus pneumoniae since the introduction of the seven-valent pneumococcal conjugate vaccine compared with isolates of other serotypes, according to recent data.

The study was based on retrospective chart reviews of 43 children diagnosed with pneumococcal mastoiditis between January 1995 and June 2007 via middle ear fluid or mastoid bone specimens at the Texas Children’s Hospital in Houston. The data were published in Pediatrics.

Incidence of pneumococcal mastoiditis caused by serotype 19A has increased at the Texas Children’s Hospital since the serotype’s discovery in 2003, and by 2006, 19A accounted for all cases at the hospital. Subperiosteal abscesses were observed in all children with 19A mastoiditis, compared with only two children without the serotype. Eighty-nine percent of those with serotype 19A had mastoidectomy compared with 45% of the non-19A group. Additionally, the 13 patients who had received the seven-valent pneumococcal conjugate vaccine (PCV7, Prevnar, Wyeth) tested positive for 19A isolates.

Shifts in the severity of pneumococcal mastoiditis caused by serotype 19A isolates will have important implications for disease management, according to the researchers. Previously, noncoalescent mastoiditis was treated with IV antibiotic therapy and myringotomy or tympanostomy tube placement. Physicians proceeded to mastoidectomy only after these traditional treatments failed.

“Among our patient population, children are now presenting with more complicated disease with not only coalescence but also subperiosteal abscesses,” the researchers wrote. “Severity of presentation often requires surgical intervention before a trial of antibiotic therapy.”

The researchers expect a similar trend to occur in other communities where routine PCV7 administration is common. “Physicians should be aware that this infection may be more aggressive and, depending on the circulating clones, more complicated to treat because of resistance to multiple antibiotics,” they wrote.

For more information:

• Ongkasuwan J, Valdez T, Hulten K, et al. Pneumococcal mastoiditis in children and the emergence of multidrug-resistant serotype 19A isolates. Pediatrics. 2008;122:34-39.