{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T18:27:34Z","timestamp":1780511254348,"version":"3.54.1"},"reference-count":0,"publisher":"Journal of Infection in Developing Countries","issue":"03","license":[{"start":{"date-parts":[[2025,3,31]],"date-time":"2025-03-31T00:00:00Z","timestamp":1743379200000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Infect Dev Ctries"],"abstract":"<jats:p>Introduction: Nowadays, treating serious infections caused by multi-drug resistant Gram-negative bacteria is best left to the antiquated medication \"colistin.\". There have been reports of colistin-resistant (Col-R) and heteroresistant (hR) MDR and XDR-GNB strains worldwide. Therefore, we aimed to ascertain the rate of colistin resistance, certain potential resistance mechanisms, and heteroresistance in colistin-susceptible (Col-S) clinical isolates.\nMethodology: Identification and Antibiotic susceptibility test (AST) for all isolates were determined by Vitek-2 automated system. The Col-S strains were evaluated for heteroresistance using the population analysis profiling (PAP) method, while the Col-R strains were tested for mcr-1 gene activity by combined disk test (CDT) and colistin minimum inhibitory concentration reduction (CMR) test. The efflux pump mechanism was identified using cyanide 3-chlorophenylhydrazone (CCCP).\nResults: Out of 60 isolates enrolled in the study, AST revealed that 60% were MDR-GNB and 40% were XDR-GNB. Ten isolates were colistin resistant (16.6%). The mcr-1 gene was detected in five (5\/10) Col-R isolates by PCR. CDT test detected mcr-1 gene activity in four (4\/5) of mcr-1 gene positive isolates, while CMR test detected all. Efflux pump inhibition by CCCP showed a reduction of MICs by \u2265 8-folds in four Coli-R isolates. The frequency of carbapenem resistance (CR) within Col-hR strains was 75%, while ESBL was 25%.\nConclusions: The alarmingly high occurrence of colistin resistance and heteroresistance in hospital care settings is of major concern and necessitates a reassessment of recommended AST methods since it can result in colistin therapy failure.<\/jats:p>","DOI":"10.3855\/jidc.20385","type":"journal-article","created":{"date-parts":[[2025,3,31]],"date-time":"2025-03-31T13:29:41Z","timestamp":1743427781000},"page":"431-438","source":"Crossref","is-referenced-by-count":2,"title":["Resistance and heteroresistance to colistin among multidrug-resistant and extensively drug-resistant Gram-negative organisms isolated from patients admitted to Zagazig University Hospitals"],"prefix":"10.3855","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-1041-6872","authenticated-orcid":false,"given":"Salah Al-Sayed Ibrahim","family":"Ali","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aya Ahmed","family":"Ghamry","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Seham K","family":"Khirala","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Asmaa M","family":"El-Nasser","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fatma M Attia","family":"Al-Sayed","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fatma Atef","family":"Ibrahim","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"2222","published-online":{"date-parts":[[2025,3,31]]},"container-title":["The Journal of Infection in Developing Countries"],"original-title":[],"link":[{"URL":"https:\/\/www.jidc.org\/index.php\/journal\/article\/download\/20385\/3614","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.jidc.org\/index.php\/journal\/article\/download\/20385\/3614","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,3,31]],"date-time":"2025-03-31T13:29:41Z","timestamp":1743427781000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.jidc.org\/index.php\/journal\/article\/view\/20385"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,3,31]]},"references-count":0,"journal-issue":{"issue":"03","published-online":{"date-parts":[[2025,3,31]]}},"URL":"https:\/\/doi.org\/10.3855\/jidc.20385","relation":{},"ISSN":["1972-2680"],"issn-type":[{"value":"1972-2680","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,3,31]]}}}