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Methicillin-resistant staphylococci and ofloxacin-resistant bacteria from clinically healthy conjunctivas
K Watanabe1, K Numata-Watanabe, S Hayasaka
1Department of Ophthalmology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan. ophthal@ms.toyama-mpu.ac.jp
Abstract:
We evaluated the existence of methicillin (DMPPC)-resistant staphylococci and ofloxacin (OFLX)-resistant bacteria among preoperative patients at an eye clinic. Bacterial growth was studied in 194 conjunctival specimens of 125 preoperative patients without signs of ocular infection. Specimens were evaluated for growth of bacteria on Drigalski's plates, blood agar plates, or chocolate agar plates for 2 days at 37 degrees C. Susceptibilities of the strain to DMPPX, OFLX, minocycline (MINO), gentamicin (GM), erythromycin (EM), cefmenoxime (CMX), chloramphenicol (CP), and sulbenicillin (SBPC) were determined by the disk diffusion method. When DMPPC-resistant Staphylococcus aureus (MRSA) or DMPPC-resistant coagulase- negative staphylococci (MRCNS) were isolated, the susceptibility of the isolated strains to vancomycin (VCM) was additionally examined by the disk diffusion method. Of the 125 preoperative patients (194 eyes), 109 patients (159 eyes) had positive bacterial growth. Methicillin-resistant Staphylococcus aureus (MRSA) were positive in 1 patient. Methicillin-resistant coagulase-negative staphylococci (MRCNS) were positive in another patient. Two eyes with MRSA or MRCNS growth were treated with topical instillation of VCM, which was more sensitive than MINO and GM. They underwent the planned surgery after two subsequent tests showing negative growth. Of 120 isolated coagulase-negative staphylococci (CNS) 8 (6.7%) were resistant to OFLX. OFLX-resistant CNS were sensitive to MINO, CMX, and CP, but also resistant to SBPC. Of 114 isolated aerobic gram-positive rods (GPR), 55 (48.2%) were resistant to OFLX. OFLX-resistant aerobic GPR were sensitive to MINO, CMX, SBPC, and DMPPC. The 157 eyes with positive bacterial growth other than MRSA were treated with topical instillation of sensitive antibiotics. The present findings indicate that DMPPC-resistant staphylococci and OFLX-resistant bacteria exist in conjunctivas without signs of infection.