http://www2.epediatricnews.com/scripts/om.dll/serve?action=searchDB&searchDBfor=art&artType=misc&id=aqp030370911

Children with otitis media
Erythromycin Resistance Increased Over 6 Years

Heidi Splete
Senior Writer
 

There was a steady increase in erythromycin resistance in middle ear isolates of children with otitis media from 15% in 1994-1995 to 56% in 1999-2000 in a multicenter cohort, said Edward O. Mason Jr., Ph.D., of Baylor College of Medicine, Houston, and his associates.

An increase in Streptococcus pneumoniae resistance to erythromycin in children with otitis media was associated with either macrolide or -lactam therapy within 30 days of isolate collection (but not with any specific macrolide); age less than 3 years; non-African American ethnicity; and collection of the isolate at the time of tympanostomy tube placement in an ongoing surveillance study (Pediatr. Infect. Dis. J. 22[7]: 623-27, 2003).

In a study of 1,088 isolates from children younger than 4 years, resistance was significantly lower (25%) in children of African American ethnicity. Resistance appeared to decrease with increasing age, from 43% in children under age 1 year to 29% at 3 years to 16% at 4 years.

The proportion of resistant phenotype remained constant during the 6-year study—75% M phenotype and 25% MLS_B phenotype—so the isolates remained susceptible to clindamycin, Dr. Mason and his associates said.

Antibiotics given within 30 days of an occurrence of pneumococcal otitis media had an impact on the resistance of the isolate. Resistance was lowest in children who had not been exposed to antibiotics within 30 days of their otitis media infections. Although penicillin resistance approximately doubled after exposure to any antibiotic, macrolide resistance was greatest after exposure to macrolides, the researchers noted.

As for serogroup susceptibility, 84% of the isolates came from pneumococci in serogroups that are part of the 7-valent pneumococcal conjugate vaccine. Serogroup 19 was the most frequently isolated serogroup and showed the highest rate of erythromycin resistance at 51%.