{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T01:24:13Z","timestamp":1790558653886,"version":"4.1.0"},"reference-count":49,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2015,10,20]],"date-time":"2015-10-20T00:00:00Z","timestamp":1445299200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Marine Drugs"],"abstract":"<jats:p>External otitis is a diffuse inflammation around the external auditory canal and auricle, which is often occurred by microbial infection. This disease is generally treated using antibiotics, but the frequent occurrence of antibiotic resistance requires the development of new antibiotic agents. In this context, unexplored bioactive natural candidates could be a chance for the production of targeted drugs provided with antimicrobial activity. In this paper, microbial pathogens were isolated from patients with external otitis using ear swabs for over one year, and the antimicrobial activity of the  two methanol extracts from selected marine (Dunaliella salina) and freshwater (Pseudokirchneriella subcapitata) microalgae was tested on the isolated pathogens. Totally, 114 bacterial and 11 fungal strains were isolated, of which Staphylococcus spp. (28.8%) and Pseudomonas aeruginosa (P. aeruginosa) (24.8%) were the major pathogens. Only three Staphylococcus aureus (S. aureus) strains and 11 coagulase-negative Staphylococci showed resistance to methicillin. The two algal extracts showed interesting antimicrobial properties, which mostly inhibited the growth of isolated S. aureus, P. aeruginosa, Escherichia coli, and Klebsiella spp. with MICs range of 1.4 \u00d7 109 to 2.2 \u00d7 1010 cells\/mL. These results suggest that the two algae have potential as resources for the development of antimicrobial agents.<\/jats:p>","DOI":"10.3390\/md13106440","type":"journal-article","created":{"date-parts":[[2015,10,20]],"date-time":"2015-10-20T16:21:51Z","timestamp":1445358111000},"page":"6440-6452","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":53,"title":["Assessment of the Antimicrobial Activity of Algae Extracts on Bacteria Responsible of External Otitis"],"prefix":"10.3390","volume":"13","author":[{"given":"Gianluca","family":"Pane","sequence":"first","affiliation":[{"name":"Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC), Sezione di Otorinolaringoiatria, Universit\u00e0 di Genova, Largo R. Benzi 10, Genova 16132, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gabriele","family":"Cacciola","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC), Sezione di Microbiologia, Universit\u00e0 di Genova, Largo R. Benzi 10, Genova 16132, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elisabetta","family":"Giacco","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze della Terra, dell\u2019Ambiente e della Vita (DISTAV), Universit\u00e0 di Genova, Viale Benedetto XV 5, Genova 16132, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gian","family":"Mariottini","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze della Terra, dell\u2019Ambiente e della Vita (DISTAV), Universit\u00e0 di Genova, Viale Benedetto XV 5, Genova 16132, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0030-1340","authenticated-orcid":false,"given":"Erika","family":"Coppo","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC), Sezione di Microbiologia, Universit\u00e0 di Genova, Largo R. Benzi 10, Genova 16132, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2015,10,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"S4","DOI":"10.1016\/j.otohns.2006.02.014","article-title":"Clinical practice guideline: Acute otitis externa","volume":"134","author":"Rosenfeld","year":"2006","journal-title":"Otolaryngol. Head Neck Surg."},{"key":"ref_2","first-page":"927","article-title":"Otitis externa: A practical guide to treatment and prevention","volume":"63","author":"Sander","year":"2001","journal-title":"Am. Fam. Phys."},{"key":"ref_3","first-page":"1222","article-title":"Acute otitis externa in children","volume":"58","author":"McWilliams","year":"2012","journal-title":"Can. Fam. Phys."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"753","DOI":"10.1007\/s00405-011-1687-7","article-title":"The management of otitis externa in UK general practice","volume":"269","author":"Pabla","year":"2012","journal-title":"Eur. Arch. Otorhinolaryngol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"392","DOI":"10.4066\/AMJ.2014.2094","article-title":"A study of acute otitis externa at Wellington Hospital, 2007\u20132011","volume":"7","author":"Jayakar","year":"2014","journal-title":"Australas. Med. J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"414","DOI":"10.1177\/0194599811406797","article-title":"Initial impact of the acute otitis externa clinical practice guideline on clinical care","volume":"145","author":"Bhattacharyya","year":"2011","journal-title":"Otolaryngol. Head Neck Surg."},{"key":"ref_7","unstructured":"Albera, R., and Rossi, G. (2012). Otorinolaringoiatria, Minerva Medica. [3rd ed.]."},{"key":"ref_8","first-page":"325","article-title":"Treatment of acute otitis externa with ciprofloxacin otic 0.2% antibiotic ear solution","volume":"7","author":"Eichel","year":"2011","journal-title":"Ther. Clin. Risk Manag."},{"key":"ref_9","first-page":"1055","article-title":"Acute otitis externa: An update","volume":"86","author":"Schaefer","year":"2012","journal-title":"Am. Fam. Phys."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1039\/a902202c","article-title":"The influence of natural products upon drug discovery","volume":"17","author":"Newman","year":"2000","journal-title":"Nat. Prod. Rep."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"5","DOI":"10.3390\/md101005","article-title":"Drugs from the sea\u2014Opportunities and obstacles","volume":"1","author":"Proksch","year":"2003","journal-title":"Mar. Drugs"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1022","DOI":"10.1021\/np030096l","article-title":"Natural products as sources of new drugs over the period 1981\u20132002","volume":"66","author":"Newman","year":"2003","journal-title":"J. Nat. Prod."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1039\/np9941100355","article-title":"Marine natural products","volume":"11","author":"Faulkner","year":"1994","journal-title":"Nat. Prod. Rep."},{"key":"ref_14","first-page":"419","article-title":"Marine microorganisms: A new biomedical resource","volume":"Volume 1","author":"Attaway","year":"1993","journal-title":"Marine Biotechnology. Pharmaceutical and Bioactive Natural Products"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1685","DOI":"10.1021\/cr00021a002","article-title":"Microalgal metabolites","volume":"93","author":"Shmizu","year":"1993","journal-title":"Chem. Rev."},{"key":"ref_16","first-page":"391","article-title":"Dinoflagellates as sources of bioactive molecules","volume":"Volume 1","author":"Attaway","year":"1993","journal-title":"Marine Biotechnology. Pharmaceutical and Bioactive Natural Products"},{"key":"ref_17","unstructured":"Butcher, R.W. (1959). An Introductory Account of the Smaller Algae of British Coastal Waters, Ministry of Agriculture, Fisheries and Food, Fishery Investigations."},{"key":"ref_18","unstructured":"Passarelli, P., and Sbalchiero, A. (2005). Notiziario dei Metodi Analitici N.1, IRSA-CNR."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1016\/j.chemosphere.2014.11.070","article-title":"Experimental assessment of the bioconcentration of 15N-tamoxifen in Pseudokirchneriella subcapitata","volume":"122","author":"Orias","year":"2015","journal-title":"Chemosphere"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1016\/j.ecoenv.2015.04.021","article-title":"Ecotoxicological assessment of the micelle encapsulator F-500","volume":"118","author":"Pane","year":"2015","journal-title":"Ecotoxicol. Environ. Saf."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2471","DOI":"10.4315\/0362-028X-69.10.2471","article-title":"Dunaliella salina microalga pressurized liquid extracts as potential antimicrobials","volume":"69","author":"Herrero","year":"2006","journal-title":"J. Food Prot."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2138","DOI":"10.4315\/0362-028X-71.10.2138","article-title":"Antimicrobial activity of sub- and supercritical CO2 extracts of the green alga Dunaliella salina","volume":"71","author":"Mendiola","year":"2008","journal-title":"J. Food Prot."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"16","DOI":"10.17485\/ijst\/2009\/v2i8.10","article-title":"In vitro studies on bactericidal activity and sensitivity pattern of isolated marine microalgae against selective human bacterial pathogens","volume":"2","author":"Srinivasakumar","year":"2009","journal-title":"Indian J. Sci. Technol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1016\/0960-8524(93)90189-I","article-title":"Antibiotic substances produced by a marine green alga, Dunaliella primolecta","volume":"44","author":"Chang","year":"1993","journal-title":"Bioresour. Technol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1007\/BF00693057","article-title":"Antibiotic effect of linolenic acid from Chlorococcum strain HS-101 and Dunaliella primolecta on methicillin-resistant Staphylococcus aureus","volume":"7","author":"Ohta","year":"1995","journal-title":"J. Appl. Phycol."},{"key":"ref_26","first-page":"146","article-title":"Evaluaci\u00f3n de la actividad antibacteriana de diferentes especies de fitoplancton","volume":"45","year":"2010","journal-title":"Rev. Biol. Mar. Oceanogr."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Kaushik, V., Malik, T., and Saeed, S.R. (2010). Interventions for acute otitis externa. Cochrane Database Syst. Rev.","DOI":"10.1002\/14651858.CD004740.pub2"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/S0140-6736(01)05321-1","article-title":"Antibiotic resistance of bacteria in biofilms","volume":"358","author":"Stewart","year":"2001","journal-title":"Lancet"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"668","DOI":"10.1097\/MLG.0b013e318030e422","article-title":"Biofilms in ear, nose, and throat infections: How important are they?","volume":"117","author":"Vlastarakos","year":"2007","journal-title":"Laryngoscope"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"14820","DOI":"10.1007\/s11356-015-4717-y","article-title":"Phenolic profile of Dunaliella tertiolecta growing under high levels of copper and iron","volume":"22","author":"Rico","year":"2015","journal-title":"Environ. Sci. Pullut. Res. Int."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"380","DOI":"10.2174\/138920101504140825121142","article-title":"Antibacterial activity of polyphenols","volume":"15","author":"Coppo","year":"2014","journal-title":"Curr. Pharm. Biotechnol."},{"key":"ref_32","first-page":"142","article-title":"Studies on Chlorella vulgaris V: Some properties of the growth inhibitor formed by Chlorella cells","volume":"29","author":"Pratt","year":"1942","journal-title":"Am. J. Bot."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"877","DOI":"10.1139\/m66-120","article-title":"The antibacterial activity of planktonic algae","volume":"12","author":"Duff","year":"1966","journal-title":"Can. J. Microbiol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1007\/BF01689380","article-title":"Comparison of antibiotic production from four ecotypes of the marine alga, Dunaliella","volume":"40","author":"Lustigman","year":"1988","journal-title":"Bull. Environ. Contam. Toxicol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"2510","DOI":"10.3390\/md11072510","article-title":"Marine pharmacology in 2009\u20132011: Marine compounds with antibacterial, antidiabetic, antifungal, anti-inflammatory, antiprotozoal, antituberculosis, and antiviral activities; affecting the immune and nervous systems, and other miscellaneous mechanisms of action","volume":"11","author":"Mayer","year":"2013","journal-title":"Mar. Drugs"},{"key":"ref_36","first-page":"1","article-title":"Screening for antimicrobial agent production of some microalgae in freshwater","volume":"2","author":"Katircioglu","year":"2005","journal-title":"Internet J. Microbiol."},{"key":"ref_37","unstructured":"M\u00e9ndez-Vilas, A. (2011). Science Against Microbial Pathogens: Communicating Current Research and Technological Advances, Formatex Research Center."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Sanmukh, S., Bruno, B., Ramakrishnan, U., Khairnar, K., Swaminathan, S., and Paunikar, W. (2014). Bioactive compounds derived from microalgae showing antimicrobial activities. J. Aquac. Res. Dev., 5.","DOI":"10.4172\/2155-9546.1000224"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"145","DOI":"10.3184\/003685015X14298590596266","article-title":"Cyanobacteria and microalgae: A renewable source of bioactive compounds and other chemicals","volume":"98","author":"Pais","year":"2015","journal-title":"Sci. Prog."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"316","DOI":"10.1016\/j.fsi.2008.07.004","article-title":"Transgenic microalgae as a non-antibiotic bactericide producer to defend against bacterial pathogen infection in the fish digestive tract","volume":"26","author":"Li","year":"2009","journal-title":"Fish Shellfish Immunol."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Stengel, D.B., and Connan, S. (2015). Marine algae: A source of biomass for biotechnological applications. Method Mol. Biol., 1308.","DOI":"10.1007\/978-1-4939-2684-8_1"},{"key":"ref_42","unstructured":"Clinical and Laboratory Standards Institute (CLSI) (2012). Performance Standards for Antimicrobial Disk Susceptibility Tests; Approved Standard\u2014Eleventh Edition. Document M02-A11, Clinical and Laboratory Standards Institute (CLSI)."},{"key":"ref_43","unstructured":"Clinical and Laboratory Standards Institute (CLSI) (2012). Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard\u2014Ninth Edition. Document M07-A9, Clinical and Laboratory Standards Institute (CLSI)."},{"key":"ref_44","unstructured":"European Committee on Antimicrobial Susceptibility Testing (EUCAST) Breakpoint Tables for Interpretation of MICs and Zone Diameters. Available online: http\/\/www.eucast.org\/clinical_breakpoints\/."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"996","DOI":"10.1128\/jcm.22.6.996-1006.1985","article-title":"Adherence of coagulase-negative staphylococci (CoNS) to plastic tissue culture plates: A quantitative model for the adherence of staphylococci to medical devices","volume":"22","author":"Christensen","year":"1985","journal-title":"J. Clin. Microbiol."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"321","DOI":"10.1016\/j.ijantimicag.2007.11.012","article-title":"Activity of daptomycin on biofilms produced on a plastic support by Staphylococcus spp.","volume":"31","author":"Roveta","year":"2008","journal-title":"Int. J. Antimicrob. Agents"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"872","DOI":"10.1136\/jcp.42.8.872","article-title":"New method for detecting slime production by coagulase negative staphylococci","volume":"42","author":"Freeman","year":"1989","journal-title":"J. Clin. Pathol."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"2151","DOI":"10.1128\/JCM.39.6.2151-2156.2001","article-title":"Presence of icaA and icaD genes and slime production in a collection of staphylococcal strains from catheter-associated infections","volume":"39","author":"Arciola","year":"2001","journal-title":"J. Clin. Microbiol."},{"key":"ref_49","unstructured":"Walne, P.R. (1966). Fishery Investigations Series II, Ministry of Agriculture, Fisheries and Food."}],"container-title":["Marine Drugs"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1660-3397\/13\/10\/6440\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T20:50:27Z","timestamp":1760215827000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1660-3397\/13\/10\/6440"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2015,10,20]]},"references-count":49,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2015,10]]}},"alternative-id":["md13106440"],"URL":"https:\/\/doi.org\/10.3390\/md13106440","relation":{},"ISSN":["1660-3397"],"issn-type":[{"value":"1660-3397","type":"electronic"}],"subject":[],"published":{"date-parts":[[2015,10,20]]}}}