Purpose:
S. pneumoniae colonizes the upper respiratory tract and frequently causes severe infections. It is also a common cause of bacterial conjunctivitis, especially in infants and children. An increase in antibiotic resistance has emerged in recent years, limiting available treatment options. This study was undertaken to evaluate the occurrence of drug-resistant isolates in bacterial conjunctivitis in 2005-2008 in the US.
Methods:
Minimum inhibitory concentrations (MIC) for isolates from three clinical trials with besifloxacin ophthalmic suspension, 0.6%, were determined for 17 antibacterials by broth microdilution according to Clinical and Laboratory Standards Institute (CLSI) methods. Where available, CLSI resistance breakpoints were used to categorize isolates as susceptible, intermediate, or resistant.
Results:
MIC values and the percentage of non-susceptible isolates for all agents (except for ciprofloxacin, ofloxacin, ceftriaxone, linezolid, and vancomycin) are shown in the table. No resistance to fluoroquinolones, ceftriaxone, linezolid, or vancomycin was observed. Of all isolates, 22.5% were resistant to more than three classes of antibiotics and 5% were resistant to five or more.
Conclusions:
Antibiotic resistance is widespread in S. pneumoniae isolates from patients with bacterial conjunctivitis. Since most cases of bacterial conjunctivitis are treated empirically, antibacterial agents with a broad spectrum of activity and a low prevalence of resistance, such as fluoroquinolones, remain viable treatment options.
Keywords: antibiotics/antifungals/antiparasitics • bacterial disease • conjunctivitis