September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Staphylococcus spp. from ocular infections: Fluctuations in in vitro susceptibility to fluoroquinolones over a decade
Author Affiliations & Notes
  • Joveeta Joseph Ruben
    Jhaveri Microbiology Centre, L.V.Prasad Eye Institute, Hyderabad, Telangana, India
  • Bhavani Sontam
    Jhaveri Microbiology Centre, L.V.Prasad Eye Institute, Hyderabad, Telangana, India
  • Bhupesh Bagga
    L.V.Prasad Eye Institute, Hyderabad, India
  • Savitri Sharma
    Jhaveri Microbiology Centre, L.V.Prasad Eye Institute, Hyderabad, Telangana, India
  • Footnotes
    Commercial Relationships   Joveeta Joseph Ruben, None; Bhavani Sontam, None; Bhupesh Bagga, None; Savitri Sharma, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 5411. doi:
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      Joveeta Joseph Ruben, Bhavani Sontam, Bhupesh Bagga, Savitri Sharma; Staphylococcus spp. from ocular infections: Fluctuations in in vitro susceptibility to fluoroquinolones over a decade. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5411.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To compare the fluoroquinolone (FQ) susceptibility of Staphylococcus spp. isolated from patients with ocular infections for the period before and after 2008.

Methods : In part 1 the study constituted restrospective data from January 2005 through June 2008 on in vitro susceptibility of ocular isolates of Staphylococcus spp. to FQs from our previous publication. For the period of July 2008 to June 2015 (part 2), a retrospective review of microbiology records identified 1196 Staphylococcus spp. isolated from different ocular infections. The isolates were identified using Vitek 2 compact system. In vitro antibiotic susceptibility (disk diffusion method) data of ciprofloxacin, gatifloxacin, and moxifloxacin were compared with published data of the period prior to July 2008. Part 3 consisted of a prospective study in which minimum inhibitory concentration (MIC) by E test was determined for the three FQs against 50 staphlococcal isolates.

Results : In our earlier publication, in vitro susceptibilities (% sensitive) in descending order were: gatifloxacin, 66.4%> moxifloxacin, 41.1%> ciprofloxacin, 37.3%. Comparatively, in this study the susceptibility percentages were: gatifloxacin, 77.9% >moxifloxacin, 77.6%> ciprofloxacin, 38.8%. Evaluating the annual changes in susceptibility, a significantly decreasing trend of gatifloxacin susceptibility (p<0.0001) was observed throughout the last six years (87% in 2008-2009 to 39.8% in 2014-2015), with a concomitant increase in resistant strains (4.3% in 2008-2009 versus 45.8% in 2014-2015). Conversely moxifloxacin showed a susceptibility of 68.6% in 2008-2009, which increased to 80.1% in 2014-2015. Ciprofloxacin resistant isolates (565/1196) demonstrated in vitro cross-resistance to gatifloxacin (122/565, 21.6%) and moxifloxacin (94/565, 16.6%). Additionally, the MIC50 and MIC90 of the 50 isolates tested in part 3 were respectively 3 μg/mL and ≥32 μg/mL for gatifloxacin and 1.5 μg/mL and 8 μg/mL for moxifloxacin, while for ciprofloxacin, both were ≥32 μg/mL.

Conclusions : Contrary to our earlier publication, current laboratory data suggests greater susceptibility to moxifloxacin compared to gatifloxacin among ocular Staphylococcus spp. isolates with no change in susceptibility to ciprofloxacin. While the cause for the shift is unclear, a judicious use of moxifloxacin is recommended.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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