Correlation of proteinase production with amphotericin B resistance in fungi from mycotic keratitis.
Two hundred fungal isolates (Aspergillus and Fusarium species) from mycotic keratitis were tested for in vitro susceptibilities to amphotericin B and proteinase production. Geometric mean MICs for all fungal species increased fourfold with thousandfold increase in the inoculum. The MIC(50) and MIC(90) values ranged between 3.12-6.25 and 3.12-12.5 microg/ml, respectively. Proteinase production was noted in 113 (56.5%) isolates. Ninety-eight (49%) showed MICs of > or =1.56 microg/ml that was above the criteria of > or =1 microg/ml for amphotericin B resistance (CLSI). Seventy-three (74.5%) of these 98 isolates were proteinase producers, whereas only 40 (39.2%) of the remaining 102 with low MICs (<1.56 microg/ml) were proteinase producers (p < 0.001). Proteinase seems to be an important virulence marker of filamentous fungi in mycotic keratitis, correlating significantly with amphotericin B resistance.
Nayak
N
N
Department of Ocular Microbiology and Cornea Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, India.
Satpathy
G
G
Prasad
Sujata
S
Vajpayee
R B
RB
Pandey
R M
RM
D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D001230:Aspergillus / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D003320:Corneal Ulcer / Q000382:microbiology*; D025141:Drug Resistance, Fungal; D005670:Fusarium / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests; D009181:Mycoses / Q000382:microbiology; D010447:Peptide Hydrolases / Q000378:metabolism*
D000935:Antifungal Agents; D000666:Amphotericin B; D010447:Peptide Hydrolases