Conjunctival S.epidermidis. rapidly develops resistance

October 12, 2011

Conjunctival S.epidermidis. repeatedly exposed to fluoroquinolone or azithromycin antibiotics quickly develops resistance in patients undergoing serial unilateral intravitreal (IVT) injections for choroidal neovascularization

Conjunctival S.epidermidis. repeatedly exposed to fluoroquinolone or azithromycin antibiotics quickly develops resistance in patients undergoing serial unilateral intravitreal (IVT) injections for choroidal neovascularization, states a paper published in Ophthalmmology.

A team led by Dr Stephen J. Kim, Vanderbilt Eye Institute, Nashville, Tennessee, USA, performed a prospective, controlled, longitudinal study with 1-year follow-up on 48 eyes of 24 patients. Each patient was administered 4 consecutive monthly serial unilateral intravitreal (IVT) injections for choroidal neovascularization.

The purpose of the study was to analyze the occurrence of multidrug-resistant Staphylococcus epidermidis after the repetition of conjunctival exposure topical macrolide or fluoroquinolone antibiotics. The main outcome measure was the antibiotic susceptibility patterns and multidrug resistance of Staphylococcus epidermidis.

After 4 consecutive treatments, 58 isolates of S. epidermidis were separated from control and treated eyes. In 69% of S. epidermidis isolated from control eyes there was resistance to 3 or more antibiotics, compared to 90% from treated eyes.

From control and treated eyes there was a total of 46 and 38 isolates of S. epidermidis, respectively. In 48% of control eyes and 71% of treated eyes there was a resistance to 5 or more antibiotics. S. epidermidis developed resistance to several fluoroquinolone-treated eyes compared to control eyes. The organisms also developed resistance to trimethoprim/sulfamethoxazole, gentamicin, and clindamycin.

A large number of azithromycin-treated eyes developed S. epidermidis resistant to macrolides, compared with control eyes. The azithromycin-treated eyes also developed a higher resistance to trimethoprim/sulfamethoxazole and doxycycline.