Pathogen Shifts and Changing Cure Rates for Otitis Media and Tonsillopharyngitis

Abstract

Pneumococcal conjugate vaccine use has caused a decrease in the incidence of recurrent and refractory acute otitis media in the United States and a shift in the predominant pathogens. Now Haemophilus influenzae is the most commonly isolated organism (about 60% of the total), and more than half the strains make beta-lactamase, rendering them resistant to amoxicillin. Penicillin nonsusceptible pneumococci, the main target of antibiotic therapy in the 1990s, has become a much less common isolate (10%- 25% of the total). These changes impact antibiotic selection for acute otitis media. Penicillin treatment of group A streptococcal tonsillopharyngitis does not meet the minimum United States Food and Drug Administration standards for first-line treatment, which is 85% or greater eradication at the end of therapy. Recent results with amoxicillin suggest its efficacy is also waning. Cephalosporins have the highest bacteriologic and clinical efficacy. This has implications for optimal antibiotic therapy.

Indications for tonsillectomy: A 10 year retrospective review

“…However, antibiotic resistance and changing virulence of organisms, related to antibiotic overuse may cause recurrent tonsillitis to become a more prevalent indication for surgery in the future. The 1950s when penicillin was introduced for the treatment of streptococcal tonsillitis the failure rate was only 5-8%, but however it now exceeds 20% [28]. The impact of antibiotics not only induces adaptations important to virulence in pathogenic organisms but can dampen the bacterial interference of mucosal flora.…”

Surveillance study of the susceptibility of Haemophilus influenzae to various antibacterial agents in Europe and Canada

“…The introduction of the 7-Valent Pneumococcal Conjugate Vaccine (PCV7) in the USA resulted in a significant shift in the upper respiratory tract pathogenic microflora away from Streptococcus pneumoniae and towards organisms such as H. influenzae [1][2][3][4] . The same vaccine program has now been introduced into several European countries and Canada 5 and a similar shift can be anticipated to occur in these regions, thus leading to the increased clinical importance of H. influenzae as a respiratory tract pathogen.…”

Variations in Amoxicillin Pharmacokinetic/Pharmacodynamic Parameters May Explain Treatment Failures in Acute Otitis Media

“…The importance of this variability in amoxicillin intestinal absorption cannot be overemphasized, given the current clinical need for high-dose 80-90 mg kg day amoxicillin regimens to overcome penicillin resistance in S. pneumoniae. [42] The primary mechanism of S. pneumoniae resistance to penicillin (amoxicillin) involves mutations in this otopathogen's target penicillin binding proteins, [43,44] and high-dose amoxicillin regimens result in higher drug concentrations at pathogen target receptor site(s), thereby overcoming this resistance by simple mass action. This dependence on higher drug concentrations from higher individual oral amoxicillin doses underscores the importance of consistent and effective intestinal absorption with oral dosing.…”