Microbiological etiology and susceptibility of bacterial conjunctivitis isolates from clinical trials with ophthalmic, twice-daily besifloxacin.
BACKGROUND
Bacterial conjunctivitis is a contagious infection of the surface of the eye usually treated empirically with topical antibiotics. Since the etiologic agent is rarely identified, it is important to monitor which bacteria cause conjunctivitis and determine their antibacterial resistance profiles.


METHODS
A total of 496 bacterial samples were isolated during a randomized, double-masked, vehicle-controlled, parallel-group study conducted in the United States with besifloxacin ophthalmic suspension 0.6% dosed twice daily. Species were determined by standard biochemical and/or molecular identification methods. Minimum inhibitory concentrations were determined according to Clinical and Laboratory Standards Institute standards.


RESULTS
The most prevalent species was Haemophilus influenzae, followed by Staphylococcus epidermidis, Staphylococcus aureus, the Streptococcus mitis group, and Streptococcus pneumoniae. One species identified in this study, which was not previously noted as a common cause of bacterial conjunctivitis, was Dolosigranulum pigrum. Ampicillin resistance was common among H. influenzae isolates, while macrolide resistance was high among S. pneumoniae, S. epidermidis, and S. aureus. The latter two species also included a number of isolates resistant to methicillin and ciprofloxacin.


CONCLUSIONS
Antibiotic resistance among isolates remains a concern and the appearance of an emerging ocular pathogen, D. pigrum, suggests the need for continued observation. The topical ophthalmic fluoroquinolones continue to provide a good balance of low to moderate (i.e., manageable) levels of resistance plus broad-spectrum coverage for empiric treatment of ocular infections.
Bausch & Lomb, 1400 North Goodman St., Rochester, NY, 14609, USA, wolfgang.haas@bausch.com.
Wolfgang
W
Haas
Lynne S
LS
Gearinger
Christine K
CK
Hesje
Christine M
CM
Sanfilippo
Timothy W
TW
Morris
D060433:Administration, Ophthalmic; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001381:Azepines / Q000008:administration & dosage / Q000627:therapeutic use*; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification; D001431:Bacteriological Techniques; D002648:Child; D002675:Child, Preschool; D002986:Clinical Trials as Topic; D003234:Conjunctivitis, Bacterial / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*; D004334:Drug Administration Schedule; D024881:Drug Resistance, Bacterial; D005260:Female; D024841:Fluoroquinolones / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D055815:Young Adult
D000900:Anti-Bacterial Agents; D001381:Azepines; D024841:Fluoroquinolones; C522124:besifloxacin