Prof. Brien Holden Eye Research Centre; Ramayamma International Eye Bank, LV Prasad Eye Institute, Hyderabad, Telangana, India.
Jhaveri Microbiology Services, LV Prasad Eye Institute, Hyderabad, Telangana, India.
Indian J Ophthalmol. 2022 Aug;70(8):2950-2955. doi: 10.4103/ijo.IJO_12_22.
To assess the efficacy of the addition of polymyxin E (colistin) in the McCarey-Kaufman (MK) corneal storage solution against multi-drug resistant strains of Enterobacteriaceae, Staphylococcus aureus, and Candida spp.
A standard micro broth dilution test and a checkerboard assay were performed for five multi-drug resistant (MDR) clinical strains of P. aeruginosa and five clinical strains of methicillin-resistant S. aureus (MRSA) and C. albicans against colistin and gentamicin alone and in combination. The minimum inhibitory concentration (MIC) and the fractional inhibitory concentration index (FICI) were calculated to assess the efficacy of each combination.
The MIC of colistin was in the range of 1-2 μg/mL for P. aeruginosa, whereas it was 256-1024 μg/mL against S. aureus. In comparison, the MIC of gentamicin was found to be 0.5-512 μg/mL and 0.5-8 μg/mL against P. aeruginosa and S. aureus, respectively. All five isolates of C. albicans did not exhibit any susceptibility to either colistin or gentamicin even at a concentration of ≥ 512 μg/mL each. The checkerboard assay was performed to evaluate the nature of the interaction of the combination of colistin and gentamicin. Based on the FICI, it was observed that the colistin and gentamicin combination has a maximum synergistic effect (FIC <0.5) in 80% (4/5) for S. aureus isolates, whereas the maximum additive effect (FIC >0.5-4) was 100% (5/5) for P. aeruginosa and the minimum additive effect was 20% (1/5) for S. aureus isolates. Antagonism (FIC ≥ 4) was not observed in any combination between the strains used in the study. Both colistin and gentamicin alone or in combination were, however, ineffective against Candida spp.
The addition of colistin has an inhibitory effect on bacterial contamination that could be possibly caused by MDR strains and could potentially be considered as an additional additive in corneal storage media.
评估在 McCarey-Kaufman（MK）角膜储存液中添加粘菌素（多粘菌素 E）对多重耐药肠杆菌科、金黄色葡萄球菌和念珠菌属的效果。
对 5 株多重耐药（MDR）铜绿假单胞菌和 5 株耐甲氧西林金黄色葡萄球菌（MRSA）和白色念珠菌的临床分离株进行标准微量肉汤稀释试验和棋盘试验，分别评估粘菌素和庆大霉素单独和联合用药的最低抑菌浓度（MIC）和部分抑菌浓度指数（FICI）。
粘菌素对铜绿假单胞菌的 MIC 值为 1-2μg/ml，而对金黄色葡萄球菌的 MIC 值为 256-1024μg/ml。相比之下，庆大霉素对铜绿假单胞菌和金黄色葡萄球菌的 MIC 值分别为 0.5-512μg/ml 和 0.5-8μg/ml。所有 5 株白色念珠菌对粘菌素和庆大霉素均无敏感性，即使浓度均≥512μg/ml。进行棋盘试验以评估粘菌素和庆大霉素联合使用的相互作用性质。根据 FICI，观察到粘菌素和庆大霉素联合使用对金黄色葡萄球菌分离株有 80%（4/5）具有最大协同作用（FIC<0.5），对铜绿假单胞菌有 100%（5/5）具有最大相加作用（FIC>0.5-4），而对金黄色葡萄球菌分离株的最小相加作用为 20%（1/5）。在研究中使用的菌株之间未观察到任何组合的拮抗作用（FIC≥4）。粘菌素和庆大霉素单独或联合使用对念珠菌属均无效。
添加粘菌素对可能由 MDR 菌株引起的细菌污染具有抑制作用，可作为角膜储存液的附加添加剂。
