Combination drug testing of Mycobacterium chelonae.
OBJECTIVE
Medical therapy of Mycobacterium chelonae keratitis is difficult because there are so few effective antimicrobial agents and single agent therapy frequently fails clinically. To identify more effective medical treatment regimens, the in vitro antimicrobial efficacy of amikacin, the most frequently used single agent, was investigated in combination with four antibiotics previously reported to have activity against M. chelonae: erythromycin, imipenem, ciprofloxacin, and vancomycin.


METHODS
The drug combinations were tested by the checkerboard method against seven corneal isolates of M. chelonae.


RESULTS
The combination of amikacin with erythromycin or vancomycin consistently led to synergistic or additive effect, however the minimum inhibitory concentrations for vancomycin were very high. The combination of amikacin with imipenem or ciprofloxacin led to results ranging from antagonism to additive effects.


CONCLUSIONS
Of the antibiotics tested, erythromycin showed the most activity against M. chelonae in combination with amikacin. In vitro combination drug testing of M. chelonae by the checkerboard method should be further evaluated for clinical relevance in microbial keratitis.
Matoba
A Y
AY
Houston Veterans Affair Medical Center, Baylor College of Medicine, Houston, Texas.
Lee
B L
BL
Robinson
N M
NM
Penland
R
R
Osato
M S
MS
D000583:Amikacin / Q000494:pharmacology*; D003320:Corneal Ulcer / Q000188:drug therapy / Q000382:microbiology; D004357:Drug Synergism; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D015818:Eye Infections, Bacterial / Q000188:drug therapy; D006801:Humans; D008826:Microbial Sensitivity Tests; D009165:Mycobacterium Infections, Nontuberculous / Q000188:drug therapy; D016926:Mycobacterium chelonae / Q000187:drug effects* / Q000302:isolation & purification
D000583:Amikacin