title: In vitro susceptibility of bacterial keratitis isolates to fourth-generation fluoroquinolones.
abstract: OBJECTIVE
  To study the microbiological profile of bacterial keratitis in Northern India and to determine the antibiotic sensitivity pattern of bacterial keratitis isolates to fourth-generation fluoroquinolones.
  
  
  METHODS
  Laboratory records of all consecutive cases of clinically suspected bacterial corneal ulcers were retrospectively reviewed. Data noted included microorganism isolated and antibiotic culture sensitivity to cefazolin, tobramycin, gatifloxacin, and moxifloxacin. In vitro susceptibility toward individual antibiotics was determined and compared with the potential in vitro susceptibilities to cefazolin-tobramycin, cefazolin-gatifloxacin, and cefazolin-moxifloxacin combinations.
  
  
  RESULTS
  A total of 292 bacterial isolates were identified. Of these, 255 (87.3%) were Gram-positive and 37 (12.7%) were Gram-negative. Staphylococcus epidermidis (n=227, 77.7%) was the most common organism. Overall susceptibility of isolates was 95.52% to gatifloxacin, 92.83% to moxifloxacin, 90.07% to tobramycin, and 83.56% to cefazolin (p<0.000). Organisms which showed resistance to fourth-generation fluoroquinolones included Staphylococcus epidermidis, Pseudomonas aeruginosa, viridans streptococci, Streptococcus pneumoniae, Staphylococcus aureus, and Escherichia coli. Susceptibilities to gatifloxacin and moxifloxacin were comparable with each other (p=0.312) and with potential susceptibilities to cefazolin-tobramycin (p=0.479), gatifloxacin-cefazolin (p=0.134), and moxifloxacin-cefazolin (p=0.412) combinations.
  
  
  CONCLUSIONS
  Monotherapy with moxifloxacin or gatifloxacin can be an effective alternative to cefazolin-tobramycin combination as a first-line empirical therapy for bacterial keratitis. The addition of cefazolin to a fourth-generation fluoroquinolone is of limited value.
authors.affiliation: Cornea and Refractive Surgery Service, Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Bhavna
authors.initials: B
authors.lastname: Chawla
authors.forename: Prakashchand
authors.initials: P
authors.lastname: Agarwal
authors.forename: Radhika
authors.initials: R
authors.lastname: Tandon
authors.forename: Jeewan S
authors.initials: JS
authors.lastname: Titiyal
authors.forename: Namrata
authors.initials: N
authors.lastname: Sharma
authors.forename: Tushar
authors.initials: T
authors.lastname: Agarwal
authors.forename: Niranjan
authors.initials: N
authors.lastname: Navak
authors.forename: Gita
authors.initials: G
authors.lastname: Satpathy
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D024901:Drug Resistance, Multiple, Bacterial; D015818:Eye Infections, Bacterial / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D024841:Fluoroquinolones / Q000627:therapeutic use*; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D007634:Keratitis / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D012189:Retrospective Studies
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones