Platinum spatula versus Mini-tip Culturette in culturing bacterial keratitis.
OBJECTIVE
To compare the traditional method of culturing bacterial keratitis (platinum spatula) with the use of a commercially available Mini-tip Culturette (Becton-Dickinson, Cockeysville, MD, U.S.A.).


METHODS
An experimental model of bacterial keratitis was created in rabbit corneas by intrastromal injection of bacteria. Cultures were taken of rabbit corneas with both the Mini-tip Culturette and the platinum spatula. Culture results were compared with corneal colony counts. Humans with community-acquired presumed bacterial keratitis were cultured with both the Mini-tip Culturette and the platinum spatula. The sensitivity and specificity of the Mini-tip Culturette method was determined and compared with the platinum-spatula technique.


RESULTS
Rabbit keratitis model: 100% of corneas had established infections by colony count. Each ulcer was culture positive with platinum spatula, moist Mini-tip Culturette, and dry Mini-tip Culturette. Human keratitis: Seven patients had culture-negative keratitis with both the Mini-tip Culturette and the platinum spatula. Five patients were culture positive with both the Mini-tip Culturette and the platinum spatula. One of the positive cultures had growth of multiple organisms by using the platinum spatula but not with the Mini-tip Culturette. The sensitivity of the Mini-tip Culturette was 83.3%. The specificity of the Mini-tip Culturette was 100%. Detected organisms included group A beta-hemolytic Streptococcus, S. aureus, coagulase-negative Staphylococcus, Serratia marcescens, and Pseudomonas aeruginosa.


CONCLUSIONS
The Mini-tip Culturette is a highly specific and moderately sensitive method for culturing bacterial keratitis.
Epley
K D
KD
The Krieger Eye Institute, Sinai Hospital of Baltimore, Maryland 21215, USA.
Katz
H R
HR
Herling
I
I
Lasky
J B
JB
D000818:Animals; D001419:Bacteria / Q000302:isolation & purification*; D001431:Bacteriological Techniques / Q000295:instrumentation*; D015169:Colony Count, Microbial; D003315:Cornea / Q000382:microbiology*; D003320:Corneal Ulcer / Q000175:diagnosis / Q000382:microbiology*; D004195:Disease Models, Animal; D015818:Eye Infections, Bacterial / Q000175:diagnosis / Q000382:microbiology*; D006801:Humans; D010984:Platinum; D011817:Rabbits; D012680:Sensitivity and Specificity
D010984:Platinum