{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,27]],"date-time":"2026-06-27T06:40:34Z","timestamp":1782542434340,"version":"3.54.5"},"reference-count":15,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,1,12]],"date-time":"2026-01-12T00:00:00Z","timestamp":1768176000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"\n Background<\/jats:title>\n \n The emergence of extended-spectrum \u03b2-lactamase (ESBL)-producing\n Escherichia coli<\/jats:italic>\n and\n Klebsiella pneumoniae<\/jats:italic>\n presents significant challenges in treating infections caused by these pathogens. This multi-center retrospective study investigated the prevalence of OXA-1 and TEM-1 genes in ESBL-producing\n E. coli<\/jats:italic>\n and\n K. pneumoniae<\/jats:italic>\n , along with their association with piperacillin\/tazobactam susceptibility and additional antimicrobial resistance genes.\n <\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n Clinical isolates were collected from three institutions as part of routine patient care: Tripler Army Medical Center (TAMC) in Hawaii, Madigan Army Medical Center (MAMC) in Washington, and Brooke Army Medical Center (BAMC) in Southern Texas. A total of 416 isolates were analyzed through genome sequencing and CLSI-guided susceptibility testing.<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n OXA-1 and TEM-1 \u03b2-lactamase enzymes were present in 20.9% (73\/349) and 38.7% (135\/349) of the\n E. coli<\/jats:italic>\n isolates, respectively. Relative risk analysis of non-susceptibility to piperacillin\/tazobactam across isolates from the three study sites revealed a highly significant association for OXA-1 (\n P<\/jats:italic>\n &lt; 0.001), whereas no significant associations were observed for TEM-1 (\n P<\/jats:italic>\n = 0.424) or the combination of OXA-1 and TEM-1 (\n P<\/jats:italic>\n = 0.082). When analyzed by institution, the relative risk of non-susceptibility to piperacillin\/tazobactam remained highly significant for OXA-1 at TAMC and MAMC (\n P<\/jats:italic>\n &lt; 0.001 for both) but was not significant at BAMC (\n P<\/jats:italic>\n = 0.21). OXA-1 and TEM-1-positive variants showed a significant association with genes conferring resistance to other antibiotics.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n The OXA-1 gene plays a key role in resistance to piperacillin\/tazobactam in ESBL-producing organisms, with geographic differences in non-susceptibility observed. Genetic profiling and localized data are crucial for optimizing antibiotic therapy and improving treatment outcomes.<\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fcimb.2025.1694724","type":"journal-article","created":{"date-parts":[[2026,1,12]],"date-time":"2026-01-12T08:11:57Z","timestamp":1768205517000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["Correlation of OXA-1 and TEM-1 genes with antibiotic resistance to piperacillin\/tazobactam in ESBL-producing Enterobacterales: insights from a multi-center analysis"],"prefix":"10.3389","volume":"15","author":[{"given":"Edwin","family":"Kamau","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brendan M.","family":"Wong","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John L.","family":"MacArthur","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jamie L.","family":"Dombach","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,1,12]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1093\/jacamr\/dlab092","article-title":"Extended-spectrum \u03b2-lactamases: an update on their characteristics, epidemiology and detection","volume":"3","author":"Castanheira","year":"2021","journal-title":"JAC Antimicrob. 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