title: Ocular flora and their antibiotic resistance patterns in the midwest: a prospective study of patients undergoing cataract surgery.
abstract: OBJECTIVE
  To determine the spectrum of conjunctival flora and the antibiotic susceptibility profiles of patients undergoing cataract surgery at a Midwestern university.
  
  
  METHODS
  Prospective in vitro laboratory investigation of a patient cohort.
  
  
  METHODS
  Conjunctival cultures were obtained from patients undergoing cataract surgery at a single ambulatory center on the day of surgery before the instillation of any ophthalmic medications. Isolates and antibiotic susceptibility profiles were identified using standard microbiological techniques.
  
  
  RESULTS
  A total of 183 eyes were cultured, yielding 225 isolates. Twenty-seven eyes (14.8%) showed no growth. Coagulase-negative staphylococci (CNS) were the most commonly isolated organisms (74.8%). Overall susceptibility was highest for gentamicin (94%), which was also true of the CNS isolates (95.0%). A total of 64.5% of CNS isolates were sensitive to ciprofloxacin; 30.1% of CNS isolates were resistant to ≥3 classes of antibiotics; 46.6% of CNS isolates were oxacillin-resistant, and they were more resistant to antibiotics than their oxacillin-sensitive counterparts (P < .001), including fluoroquinolones (P < .001). Among eyes with multiple CNS strains, 41.4% had different antibiotic susceptibility profiles even though they were the same species.
  
  
  CONCLUSIONS
  Our cohort harbored organisms with similar rates of antibiotic resistance as elsewhere in the country, including oxacillin resistance; however, the rate of fluoroquinolone resistance was less than in other reports. A surprisingly large proportion of different CNS strains from the same eye harbored different antibiotic susceptibility profiles. Our in vitro results, along with those of other investigators, should prompt further dialogue regarding antibiotic of choice for perioperative surgical prophylaxis in ophthalmic surgery.
authors.affiliation: Department of Ophthalmology, Saint Louis University School of Medicine, Saint Louis, Missouri, USA. hhsu@doheny.org
authors.forename: Hugo Y
authors.initials: HY
authors.lastname: Hsu
authors.forename: John T
authors.initials: JT
authors.lastname: Lind
authors.forename: Lili
authors.initials: L
authors.lastname: Tseng
authors.forename: Darlene
authors.initials: D
authors.lastname: Miller
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002387:Cataract Extraction; D003228:Conjunctiva / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D025141:Drug Resistance, Fungal; D005260:Female; D005658:Fungi / Q000187:drug effects / Q000302:isolation & purification*; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000302:isolation & purification*; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008923:Missouri; D010044:Outpatient Clinics, Hospital; D011446:Prospective Studies
chemical_list: D000900:Anti-Bacterial Agents