{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,22]],"date-time":"2026-03-22T05:21:51Z","timestamp":1774156911491,"version":"3.50.1"},"reference-count":9,"publisher":"Oxford University Press (OUP)","issue":"7","license":[{"start":{"date-parts":[[2020,3,28]],"date-time":"2020-03-28T00:00:00Z","timestamp":1585353600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/journals\/pages\/open_access\/funder_policies\/chorus\/standard_publication_model"}],"funder":[{"name":"University College London Hospitals"},{"DOI":"10.13039\/501100008721","name":"UCLH","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100008721","id-type":"DOI","asserted-by":"publisher"}]},{"name":"NHS Trust"},{"name":"Health Services Laboratories"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2020,7,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:sec>\n                  <jats:title>Background<\/jats:title>\n                  <jats:p>Azithromycin resistance is emerging in typhoidal Salmonella. Confirmation of azithromycin MIC is the most frequent antibiotic susceptibility request made to the Gastrointestinal Bacteria Reference Unit (GBRU) laboratory in England by local diagnostic laboratories.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Objectives<\/jats:title>\n                  <jats:p>(i) Determine concordance between local diagnostic and reference laboratory estimations of azithromycin MIC by gradient strip in Salmonella enterica serovars Typhi and Paratyphi. (ii) Consider causes of variation.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>Isolates from patients with enteric fever attending a central London hospital between May 2011 and April 2019 were tested for azithromycin susceptibility using gradient strips, according to EUCAST methodology. Matched local diagnostic and reference laboratory estimations of azithromycin and ciprofloxacin (as a comparator) MICs were included; concordance in estimations was examined.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>Local diagnostic laboratory readings overestimated azithromycin MIC values compared with the reference laboratory, resulting in poor concordance in susceptibility\/resistance attribution (concordant susceptibility interpretation in 8\/19, \u03ba\u2009=\u20090). In contrast, ciprofloxacin MIC estimation demonstrated superior concordance (concordant susceptibility interpretation in 16\/17, \u03ba\u2009=\u20090.85). None of the isolates was resistant to azithromycin at the reference laboratory and no known genes associated with azithromycin resistance were detected in any isolate using WGS.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>Overestimation of azithromycin resistance is likely to be due to difficulty in interpreting the point of intersection of the \u2018trailing edge\u2019 with the gradient strip, used to determine MIC. We advise local diagnostic laboratories to review their experience and consider adopting a \u2018second reader\u2019 system to mitigate this.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1093\/jac\/dkaa097","type":"journal-article","created":{"date-parts":[[2020,3,6]],"date-time":"2020-03-06T12:24:43Z","timestamp":1583497483000},"page":"1820-1823","source":"Crossref","is-referenced-by-count":12,"title":["Azithromycin susceptibility testing for Salmonella enterica isolates: discordances in results using MIC gradient strips"],"prefix":"10.1093","volume":"75","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2844-6261","authenticated-orcid":false,"given":"Jennifer","family":"Goldblatt","sequence":"first","affiliation":[{"name":"Department of Clinical Microbiology, University College London Hospital NHS Foundation Trust, 5th Floor, 250 Euston Road, London NW1 2PG, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andrew","family":"Ward","sequence":"first","affiliation":[{"name":"The Doctors Laboratory, The Halo Building, 1 Mabledon Place, London WC1H 9AX, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mohammed","family":"Yusuf","sequence":"first","affiliation":[{"name":"Health Services Laboratories, 1 Mabledon Place, London WC1H 9AX, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Martin","family":"Day","sequence":"first","affiliation":[{"name":"Gastrointestinal Bacteria Reference Unit, Public Health England, National Infection Service, Colindale, London NW9 5EQ, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gauri","family":"Godbole","sequence":"first","affiliation":[{"name":"Gastrointestinal Bacteria Reference Unit, Public Health England, National Infection Service, Colindale, London NW9 5EQ, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6877-2531","authenticated-orcid":false,"given":"Stephen","family":"Morris-Jones","sequence":"first","affiliation":[{"name":"Department of Clinical Microbiology, University College London Hospital NHS Foundation Trust, 5th Floor, 250 Euston Road, London NW1 2PG, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"286","published-online":{"date-parts":[[2020,3,28]]},"reference":[{"key":"2020061904534642200_dkaa097-B1","doi-asserted-by":"crossref","first-page":"1368","DOI":"10.1016\/S1473-3099(18)30483-3","article-title":"Outbreak investigation of ceftriaxone-resistant Salmonella enterica serotype Typhi and its risk factors among the general population in Hyderabad, Pakistan: a matched case-control study","volume":"18","author":"Qamar","year":"2018","journal-title":"Lancet Infect 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