In vitro susceptibility patterns of methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus corneal isolates to antibiotics.
OBJECTIVE
To determine the in vitro susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MRCNS) isolates to various antibiotics.


METHODS
All cases of bacterial keratitis caused by Staphylococcus species during 2006 and 2007 were identified. The isolates were divided according to species and susceptibility to methicillin into 4 groups: methicillin-susceptible S. aureus, methicillin-susceptible coagulase-negative Staphylococcus, MRSA, and MRCNS. Routine susceptibility testing for Staphylococcus species to methicillin and 19 other antibiotics was performed using the MicroScan POS Breakpoint Combo Panel Type 20.


RESULTS
One hundred fifty-seven isolates were identified. Forty isolates were S. aureus, including 21 MRSA, and 117 isolates were coagulase-negative Staphylococcus, including 29 MRCNS. All MRSA isolates were susceptible to gentamicin, linezolid, rifampin, tetracycline, and vancomycin and were resistant to penicillin, cefazolin, cefepime, azithromycin, erythromycin, and ofloxacin. Ninety percent of MRSA isolates were resistant to fourth-generation fluoroquinolones. All MRCNS isolates were susceptible to vancomycin, chloramphenicol, linezolid, and rifampin and were resistant to penicillin, cefazolin, cefepime, and azithromycin. Sixty-five percent of the MRCNS isolates were susceptible to fourth-generation fluoroquinolones and gentamicin.


CONCLUSIONS
All MRSA and MRCNS isolates were sensitive to vancomycin, linezolid, and rifampin. MRSA isolates were generally sensitive to gentamicin and tetracycline and resistant to fourth-generation fluoroquinolones. MRCNS isolates were not consistently sensitive to gentamicin, tetracycline, or fourth-generation fluoroquinolones.
Elsahn
Ahmed F
AF
Department of Ophthalmology, Cornea Service, Wills Eye Institute, Philadelphia, PA 19107, USA.
Yildiz
Elvin H
EH
Jungkind
Donald L
DL
Abdalla
Yasmine F
YF
Erdurmus
Mesut
M
Cremona
Federico A
FA
Rapuano
Christopher J
CJ
Hammersmith
Kristin M
KM
Cohen
Elisabeth J
EJ
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003030:Coagulase / Q000378:metabolism; D003320:Corneal Ulcer / Q000382:microbiology*; D015818:Eye Infections, Bacterial / Q000382:microbiology*; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D003030:Coagulase