{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T13:54:57Z","timestamp":1790258097569,"version":"4.1.0"},"reference-count":32,"publisher":"Microbiology Society","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2014,6,1]]},"abstract":"<jats:p>Biofilms represent microbial communities, encased in a self-produced matrix or extracellular polymeric substance. Microbial biofilms are likely responsible for a large proportion of clinically significant infections and the multicellular nature of biofilm existence has been repeatedly associated with antibiotic resistance. Classical<jats:italic>in vitro<\/jats:italic>antibiotic-susceptibility testing utilizes artificial growth media and planktonic microbes, but this method may not account for the variability inherent in environments subject to biofilm growth<jats:italic>in vivo<\/jats:italic>. Experiments were designed to test the hypothesis that nutrient concentration can modulate the antibiotic susceptibility of<jats:italic>Staphylococcus aureus<\/jats:italic>biofilms. Developing<jats:italic>S. aureus<\/jats:italic>biofilms initiated on surgical sutures, and in selected experiments planktonic cultures, were incubated for 16 h in 66\u200a% tryptic soy broth, 0.2\u200a% glucose (1\u00d7 TSBg), supplemented with bactericidal concentrations of gentamicin, streptomycin, ampicillin or vancomycin. In parallel experiments, antibiotics were added to growth medium diluted one-third (1\/3\u00d7 TSBg) or concentrated threefold (3\u00d7 TSBg). Following incubation, viable bacteria were enumerated from planktonic cultures or suture sonicates, and biofilm biomass was assayed using spectrophotometry. Interestingly, bactericidal concentrations of gentamicin (5 \u00b5g gentamicin ml<jats:sup>\u22121<\/jats:sup>) and streptomycin (32 \u00b5g streptomycin ml<jats:sup>\u22121<\/jats:sup>) inhibited biofilm formation in samples incubated in 1\/3\u00d7 or 1\u00d7 TSBg, but not in samples incubated in 3\u00d7 TSBg. The nutrient dependence of aminoglycoside susceptibility is not only associated with biofilm formation, as planktonic cultures incubated in 3\u00d7 TSBg in the presence of gentamicin also showed antibiotic resistance. These findings appeared specific for aminoglycosides because biofilm formation was inhibited in all three growth media supplemented with bactericidal concentrations of the cell wall-active antibiotics, ampicillin and vancomycin. Additional experiments showed that the ability of 3\u00d7 TSBg to overcome the antibacterial effects of gentamicin was associated with decreased uptake of gentamicin by<jats:italic>S. aureus<\/jats:italic>. Uptake is known to be decreased at low pH, and the kinetic change in pH of growth medium from biofilms incubated in 5 \u00b5g gentamicin ml<jats:sup>\u22121<\/jats:sup>in the presence of 3\u00d7 TSBg was decreased when compared with pH determinations from biofilms formed in 1\/3\u00d7 or 1\u00d7 TSBg. These studies underscore the importance of environmental factors, including nutrient concentration and pH, on the antibiotic susceptibility of<jats:italic>S. aureus<\/jats:italic>planktonic and biofilm bacteria.<\/jats:p>","DOI":"10.1099\/jmm.0.068130-0","type":"journal-article","created":{"date-parts":[[2014,4,3]],"date-time":"2014-04-03T00:21:44Z","timestamp":1396484504000},"page":"861-869","source":"Crossref","is-referenced-by-count":29,"title":["Aminoglycoside inhibition of Staphylococcus aureus biofilm formation is nutrient dependent"],"prefix":"10.1099","volume":"63","author":[{"given":"Michelle J.","family":"Henry-Stanley","sequence":"first","affiliation":[{"name":"Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Donavon J.","family":"Hess","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA"},{"name":"Department of Surgery, University of Minnesota, Minneapolis, MN, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carol L.","family":"Wells","sequence":"additional","affiliation":[{"name":"Department of Surgery, University of Minnesota, Minneapolis, MN, USA"},{"name":"Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"345","reference":[{"key":"r1","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.44.7.1818-1824.2000"},{"key":"r2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.00001-13"},{"key":"r3","article-title":"Performance Standards for Antimicrobial Susceptibility Testing; 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