Mora-Boellstorff David, Matharu Kanwal, Jhanji Vishal, Kowalski Regis P
The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Antibiotics (Basel). 2023 Jul 3;12(7):1145. doi: 10.3390/antibiotics12071145.
Systemic doxycycline has been prescribed to reduce inflammation and enhance corneal healing in bacterial keratitis. Topical autologous serum drops (ASD) containing doxycycline following oral supplementation may additionally confer an anti-bacterial effect. The potential of this supplementation was evaluated by determining the in vitro susceptibility of bacterial keratitis isolates to doxycycline.
The minimum inhibitory concentrations (MICs) of doxycycline against 100 bacterial keratitis isolates were determined using Etests. Twenty-seven , ten coagulase-negative , six , seven viridans group streptococci, seven other Gram-positive bacteria, nineteen , eight , four spp., two spp., and ten other Gram-negative bacteria isolates were tested. MICs of doxycycline were compared to a serum standard concentration of doxycycline (SSCD) of 4 µg/mL and concentrations that would be found in 50% and 20% serum component clinical preparations of ASD, corresponding to 50% SSCD (2 µg/mL) and 20% SSCD (0.8 µg/mL), respectively. MICs equal to or less than these values were used to deem a bacterial isolate susceptible.
For Gram-positive bacteria, susceptibilities to SSCD, 50% SSCD, and 20% SSCD were 86%, 65%, and 60%, respectively. For Gram-negative bacteria, susceptibilities to SSCD, 50% SSCD, and 20% SSCD were 37.2%, 23.3%, and 11.6%, respectively. Chi-squared analyses comparing Gram-positive and Gram-negative susceptibilities showed significantly greater susceptibility of Gram-positive bacteria at all three tested MICs (<0.0001, <0.0001, <0.0001).
Our data suggest that autologous serum drops containing theoretic concentrations of doxycycline may provide an additional anti-bacterial effect in the treatment of bacterial keratitis, especially for Gram-positive bacterial keratitis compared to Gram-negative bacterial keratitis.
已开具全身性强力霉素以减轻细菌性角膜炎的炎症并促进角膜愈合。口服补充后含强力霉素的局部自体血清滴剂（ASD）可能还具有抗菌作用。通过测定细菌性角膜炎分离株对强力霉素的体外敏感性来评估这种补充剂的潜力。
使用Etest测定强力霉素对100株细菌性角膜炎分离株的最低抑菌浓度（MIC）。测试了27株凝固酶阴性菌、10株、6株、7株草绿色链球菌、7株其他革兰氏阳性菌、19株、8株、4株、2株、以及10株其他革兰氏阴性菌分离株。将强力霉素的MIC与血清标准浓度的强力霉素（SSCD）4μg/mL以及在ASD的50%和20%血清成分临床制剂中会发现的浓度进行比较，分别对应50% SSCD（2μg/mL）和20% SSCD（0.8μg/mL）。等于或低于这些值的MIC用于判定细菌分离株敏感。
对于革兰氏阳性菌，对SSCD、50% SSCD和20% SSCD的敏感性分别为86%、65%和60%。对于革兰氏阴性菌，对SSCD、50% SSCD和20% SSCD的敏感性分别为37.2%、23.3%和11.6%。比较革兰氏阳性菌和革兰氏阴性菌敏感性的卡方分析显示，在所有三个测试的MIC水平上，革兰氏阳性菌的敏感性均显著更高（<0.0001，<0.0001，<0.0001）。
我们的数据表明，含有理论浓度强力霉素的自体血清滴剂在治疗细菌性角膜炎时可能提供额外的抗菌作用，特别是与革兰氏阴性细菌性角膜炎相比，对革兰氏阳性细菌性角膜炎效果更佳。
