{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:18:21Z","timestamp":1760149101932,"version":"build-2065373602"},"reference-count":35,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,7,3]],"date-time":"2023-07-03T00:00:00Z","timestamp":1688342400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Purpose: 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. Methods: The minimum inhibitory concentrations (MICs) of doxycycline against 100 bacterial keratitis isolates were determined using Etests. Twenty-seven Staphylococcus aureus, ten coagulase-negative Staphylococci, six Streptococcus pneumoniae, seven viridans group streptococci, seven other Gram-positive bacteria, nineteen Pseudomonas aeruginosa, eight Serratia marcescens, four Moraxella spp., two Haemophilus 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 \u00b5g\/mL and concentrations that would be found in 50% and 20% serum component clinical preparations of ASD, corresponding to 50% SSCD (2 \u00b5g\/mL) and 20% SSCD (0.8 \u00b5g\/mL), respectively. MICs equal to or less than these values were used to deem a bacterial isolate susceptible. Results: 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 (&lt;0.0001, &lt;0.0001, &lt;0.0001). Conclusions: 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.<\/jats:p>","DOI":"10.3390\/antibiotics12071145","type":"journal-article","created":{"date-parts":[[2023,7,3]],"date-time":"2023-07-03T00:34:08Z","timestamp":1688344448000},"page":"1145","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Can Serum Drops Containing Doxycycline Provide a Supplemental Anti-Bacterial Effect in the Treatment of Bacterial Keratitis?"],"prefix":"10.3390","volume":"12","author":[{"given":"David","family":"Mora-Boellstorff","sequence":"first","affiliation":[{"name":"The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1809-5549","authenticated-orcid":false,"given":"Kanwal","family":"Matharu","sequence":"additional","affiliation":[{"name":"The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Vishal","family":"Jhanji","sequence":"additional","affiliation":[{"name":"The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8558-0782","authenticated-orcid":false,"given":"Regis P.","family":"Kowalski","sequence":"additional","affiliation":[{"name":"The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,7,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1084","DOI":"10.1038\/s41433-020-01339-3","article-title":"Infectious keratitis: An update on epidemiology, causative microorganisms, risk factors, and antimicrobial resistance","volume":"35","author":"Ting","year":"2021","journal-title":"Eye"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"448","DOI":"10.1002\/path.1400","article-title":"Extracellular matrix remodelling: The role of matrix metalloproteinases","volume":"200","author":"Stamenkovic","year":"2003","journal-title":"J. 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