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Identification and antibiotic susceptibility of coagulase negative staphylococci isolated in corneal/external infections
  1. Antonio Pinnaa,
  2. Stefania Zanettib,
  3. Mario Sotgiua,
  4. Leonardo A Sechib,
  5. Giovanni Faddac,
  6. Francesco Cartaa
  1. aInstitute of Ophthalmology, University of Sassari, Sassari, Italy, bDepartment of Biomedical Sciences, Section of Experimental and Clinical Microbiology, University of Sassari, Sassari, Italy, cInstitute of Microbiology, Università Cattolica del Sacro Cuore, Rome, Italy
  1. Dr Antonio Pinna, Istituto di Clinica Oculistica, Università degli Studi di Sassari, Viale San Pietro 43 A, 07100 Sassari, Italy.


AIMS To identify and determine antibiotic susceptibility of coagulase negative staphylococci (CoNS) isolated from patients with chronic blepharitis, purulent conjunctivitis, and suppurative keratitis.

METHODS A retrospective review of all culture positive cases of chronic blepharitis, purulent conjunctivitis, and suppurative keratitis between July 1995 and December 1996 was performed. Cases in which CoNS were the sole isolates were analysed. Species identification was performed by using a commercially available standardised biochemical test system. Antibiotic susceptibility to penicillin, gentamicin, tetracycline, erythromycin, ciprofloxacin, and teicoplanin was determined by agar disc diffusion (Kirby–Bauer method). Teicoplanin resistance was confirmed by agar dilution.

RESULTS 42Staphylococcus epidermidis, fourS warneri, three S capitis, two S hominis, one each ofS xylosus, S simulans, S equorum, andS lugdunensis were identified. 37 CoNS were penicillin resistant, 12 gentamicin resistant, 28 tetracycline resistant, 18 erythromycin resistant, four ciprofloxacin resistant, and one teicoplanin resistant (MIC, 32 μg/ml). In total, 16 strains were resistant to three or more antibiotics.

CONCLUSION Species of CoNS apart from S epidermidis may be isolated from patients with corneal and external infection. Antibiotic susceptibility of CoNS is unpredictable and multiresistant strains are common. As a result, antibiotic susceptibility testing should be performed in all cases of clinically significant ocular infections caused by CoNS.

  • coagulase negative staphylococci
  • antibiotic susceptibility
  • ocular infections

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