{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T20:27:28Z","timestamp":1792787248461,"version":"4.5.0"},"reference-count":34,"publisher":"American Society for Microbiology","issue":"10","license":[{"start":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T00:00:00Z","timestamp":1791244800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T00:00:00Z","timestamp":1791244800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"name":"Sant\u00e9 publique France","id":[{"id":"https:\/\/ror.org\/00dfw9p58","id-type":"ROR","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001677","name":"Institut National de la Sant\u00e9 et de la Recherche M\u00e9dicale","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100001677","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Universit\u00e9 de Rennes"}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Microbiol Spectr"],"published-print":{"date-parts":[[2026,10,6]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      Delafloxacin (DLX) is a novel fluoroquinolone (FQ) with enhanced activity against gram-positive bacteria and under acidic conditions. Since the pH of urine is usually acidic, DLX could be an alternative to current drugs for urinary tract infections (UTIs), especially in male patients, for whom good prostatic tissue penetration is required. The aim of this study was to evaluate\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      the activity of DLX and FQ comparators against\n                      <jats:italic toggle=\"yes\">Enterococcus faecalis<\/jats:italic>\n                      and\n                      <jats:italic toggle=\"yes\">Enterococcus faecium<\/jats:italic>\n                      , to characterize the resistance pattern of\n                      <jats:italic toggle=\"yes\">E. faecalis<\/jats:italic>\n                      against FQs, and to decipher the genetic basis of resistance among\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      -selected mutants. DLX showed higher\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      activity than both levofloxacin and moxifloxacin against\n                      <jats:italic toggle=\"yes\">E. faecalis<\/jats:italic>\n                      , with an MIC\n                      <jats:sub>50<\/jats:sub>\n                      of 0.06 mg\/L, which was 16- and 4-fold lower than those of these two FQs, respectively. None of the three antibiotics was effective against\n                      <jats:italic toggle=\"yes\">E. faecium<\/jats:italic>\n                      (MICs mostly &gt;8 mg\/L). DLX exhibited increased activity under acidic conditions, as the MIC\n                      <jats:sub>50<\/jats:sub>\n                      for 12\n                      <jats:italic toggle=\"yes\">E. faecalis<\/jats:italic>\n                      isolates decreased by a 3-log\n                      <jats:sub>2<\/jats:sub>\n                      dilution between pH 7.2 and pH 5, whereas comparator activities were impaired. A total of 19 mutants with significant increases in DLX MICs were selected\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      , including 12\/19 (63%) with at least one mutation in the quinolone resistance-determining region (QRDR) of GyrA (mainly at the position S84). Interestingly, four mutants lacked QRDR mutations but carried mutations in\n                      <jats:italic toggle=\"yes\">eno<\/jats:italic>\n                      or\n                      <jats:italic toggle=\"yes\">infB<\/jats:italic>\n                      genes, which have not previously been reported in FQ resistance. In conclusion, DLX showed greater\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      activity than levofloxacin and moxifloxacin against\n                      <jats:italic toggle=\"yes\">E. faecalis<\/jats:italic>\n                      isolates, especially under acidic conditions, suggesting its potential use for treating male UTIs.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>IMPORTANCE<\/jats:title>\n                    <jats:p>\n                      Enterococci urinary tract infections (UTIs) are common but often difficult to treat in male patients, in whom good prostatic tissue penetration is required. Fluoroquinolones (FQs) remain attractive in this setting even though their efficacy is altered by the acidic pH of urine. Delafloxacin (DLX) is a novel FQ whose structure confers enhanced activity against gram-positive bacteria and under acidic conditions such as urine. Here, we demonstrate that DLX is substantially more active\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      against\n                      <jats:italic toggle=\"yes\">Enterococcus faecalis<\/jats:italic>\n                      than levofloxacin or moxifloxacin, an advantage further amplified under urine-mimicking acidic conditions. The low frequency of\n                      <jats:italic toggle=\"yes\">in vitro<\/jats:italic>\n                      spontaneous resistant mutants and the predominance of GyrA substitutions among mutants suggest a resistance driven by target modification. Together, these results identify DLX as a promising candidate to address an unmet need in the management of male enterococcal UTIs, but further validation in animal models and clinical studies is needed.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1128\/spectrum.01170-26","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T13:06:47Z","timestamp":1787576807000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["<i>In vitro<\/i>\n                    activity of delafloxacin against enterococcal isolates from male urinary tract infections and genetic determinants of resistance"],"prefix":"10.1128","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7577-0059","authenticated-orcid":true,"given":"Adrien","family":"Turban","sequence":"first","affiliation":[{"name":"Department of Bacteriology, University Hospital of 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