Detection of virulence factors with multiplex PCR Technique of Conjunctival Coagulase Negative-Staphylococcus (CNS) from patients undergoing cataract surgery

Abstract

Purpose: We performed a prospective study to identify by multiplex PCR (Polymerase Chain Reaction), genes encoding virulence factors (ica, Atle and mecA) in CNS isolates from the ocular microbiota of patients undergoing cataract surgery and to investigate possible changes in the Coagulase Negative-Staphylococcus (CNS) profile due to antibiotic prophylaxis.

Methods: After approval of the Institutional Review Board of our institution had been obtained, patients undergoing cataract surgery were recruited for this study at the Department of Ophthalmology, National University of Asuncion, Paraguay. Patients (n= 162) received in the eye to be operated moxifloxacin 0.5% eye drops, four times the day before surgery and a last drop one hour before surgery (T1). The other eye remained as control (T0). Conjunctival swabs were taken from both eyes one hour after the last drop. Presence of genes encoding biofilm formation (ica and atlE) and gene encoding methicillin resistance (mecA) were detected by a multiplex PCR in CNS isolates from both timepoints.

Results: Of the 162 patients, 87 eyes were positive for CNS in T0, yielding 96 CNS isolates and in T1, 70 eyes were positive, yielding 77 isolates CNS. We used for this study 43 CNS isolates from T0 and 45 from T1. Of the total CNS isolates , 81,8% (72/88) had at least one virulence factor gene (37/43 from T0 and 35/45 from T1 (p=0.314), simultaneous detection of ica and Atle genes was more frequent in T0 (n=25, 58.0%) than T1 (n=21, 46.7%), but the difference was not significant (p=0.28).

Conclusions: A high frequency of genes encoding virulence factors was observed in the coagulase-negative Staphylococcus isolates. The use of moxifloxacin did not modify significantly the CNS virulence factor profiles.