Assessment of the Antimicrobial Activity of Algae Extracts on Bacteria Responsible of External Otitis.
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 × 10⁸ to 2.2 × 10(10) cells/mL. These results suggest that the two algae have potential as resources for the development of antimicrobial agents.
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC), Sezione di Otorinolaringoiatria, Università di Genova, Largo R. Benzi 10, Genova 16132, Italy. Gianluca.Pane@unige.it.
Gianluca
G
Pane
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC), Sezione di Microbiologia, Università di Genova, Largo R. Benzi 10, Genova 16132, Italy. gabrielecacciola@live.it.
Gabriele
G
Cacciola
Dipartimento di Scienze della Terra, dell'Ambiente e della Vita (DISTAV), Università di Genova, Viale Benedetto XV 5, Genova 16132, Italy. Elisabetta.Giacco@unige.it.
Elisabetta
E
Giacco
Dipartimento di Scienze della Terra, dell'Ambiente e della Vita (DISTAV), Università di Genova, Viale Benedetto XV 5, Genova 16132, Italy. Gian.Luigi.Mariottini@unige.it.
Gian Luigi
GL
Mariottini
Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC), Sezione di Microbiologia, Università di Genova, Largo R. Benzi 10, Genova 16132, Italy. erika.coppo@unige.it.
Erika
E
Coppo
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000890:Anti-Infective Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000302:isolation & purification; D024881:Drug Resistance, Bacterial; D005260:Female; D005658:Fungi / Q000187:drug effects / Q000302:isolation & purification; D006801:Humans; D008297:Male; D058086:Microalgae / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010032:Otitis Externa / Q000188:drug therapy* / Q000382:microbiology; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D055815:Young Adult
D000890:Anti-Infective Agents; D010936:Plant Extracts
Dunaliella tertiolecta; Pseudokirchneriella subcapitata; Pseudomonas aeruginosa; Staphylococcus aureus; algae; antibiotic  activity; antimicrobial susceptibility; biofilm; external otitis