Bacteria causing recurrent, hard-to-treat ear infections are more resistant than previously reported

May 21, 1997

Bacteria linked with acute otitis media (AOM), or middle-ear infection, in children, including cases of recurrent infection and previous treatment failure, may be more difficult to cure than previously reported in other clinical studies, according to a study in this month's Pediatric Infectious Disease Journal.

This large multi-center study, involving 262 children, confirmed that the most prevalent bacteria germs responsible for causing recurrent otitis media were Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. A high level of resistance to antibiotics among two of the bacteria, S. pneumoniae and H. influenzae, was discovered -- so called "superbugs" -- which may be why these children were having recurrent ear infections.

"We found antibiotic resistance rates for H. influenzae and S. pneumoniae were higher than reported in previous studies. Of the H. influenzae isolates, 56 percent were resistant to amoxicillin, while resistance was found in 46 percent of all S. pneumoniae isolates," stated Michael E. Pichichero, M.D., the lead author of the study. Dr. Pichichero is professor of microbiology and immunology, pediatrics and medicine, University of Rochester Medical Center, and a practicing pediatrician at Elmwood Pediatric Group, Rochester, NY.

The study, entitled "Cefprozil Treatment of Persistent and Recurrent Acute Otitis Media," was designed to identify the organisms causing persistent and recurrent acute otitis media, and to assess the clinical and bacteriologic efficacy of cefprozil therapy (30 mg/kg/day, a powder for oral suspension) in two equally-divided doses for 10 days in the treatment of hard-to-treat AOM in pediatric patients. AOM, the most commonly treated illness in children under the age of five, results in 30 million doctor visits per year in the United States.

"Seventy-eight percent of the children achieved a satisfactory clinical response at the end of therapy with cefprozil. Within three to six days of treatment with cefprozil, more than 96 percent of the children in the study improved or resolved as far as fever, ear pain and irritability. This non-comparative study shows that cefprozil is an effective and well-tolerated alternative antibiotic in the treatment of children with persistent and recurrent AOM," commented Dr. Pichichero.

According to Dr. Pichichero, the study design is unusual because it included many children with a history of recurrent AOM or recent treatment failure. The majority of the children in the study (85 percent) had one or more previous episodes of AOM, and 50 percent had three or more previous episodes within 12 months of the start of the study. Children with these characteristics are often excluded from clinical trials.

The investigators noted that in previous studies, the characteristics of their participants (recurrent AOM, recent antibiotic use and persistent AOM) have each been associated with an increased incidence of antibiotic-resistant bacteria. Notably, penicillin-resistant pneumococci has been associated with previous infection and antibiotic treatment. Amoxicillin, which is chemically-related to penicillin, has traditionally been the standard therapy for treatment of AOM.

All study participants (males and females aged six months to 12 years) underwent tympanocentesis, or "ear tap," a procedure to assess and confirm bacteria found in middle ear fluids which is being used by leading-edge pediatricians and family practitioners.

Cefprozil therapy was well tolerated by children in the study, and side effects related to therapy were infrequent. The most commonly reported were diarrhea (3%) and rash (2%).

The onset of AOM -- inflammation of the middle ear caused by accumulation of fluids containing mucus and pus -- is sudden, characterized by irritability, pain, fever and pulling on the ears. According to the American Academy of Otolaryngology-Head and Neck Surgery, about one-third of all children have more than three ear infections by age three.

Cefprozil (Cefzil(r)), a broad-spectrum cephalosporin introduced in 1992, was cleared for marketing by the U.S. Food and Drug Administration for the treatment of patients with mild-to-moderate infections caused by susceptible strains of bacteria in upper and lower respiratory tract infections, as well as skin infections. Cefprozil is the only cephalosporin indicated for both sinusitis and otitis media in pediatric patients.

The study, conducted from December 1994 to October 1995, was funded by an educational grant from Bristol-Myers Squibb Company. It was conducted at 10 medical centers in the United States under a U.S. Investigational New Drug Application.

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