{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T15:40:13Z","timestamp":1787067613474,"version":"build-2736575974"},"reference-count":35,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,7,10]],"date-time":"2023-07-10T00:00:00Z","timestamp":1688947200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"University of Antwerp BOF Doctoral Project Funds","award":["40179"],"award-info":[{"award-number":["40179"]}]},{"name":"University of Antwerp Methusalem funding","award":["40179"],"award-info":[{"award-number":["40179"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Genes"],"abstract":"<jats:p>Colistin heteroresistance has been identified in several bacterial species, including Escherichia coli and Klebsiella pneumoniae, and may underlie antibiotic therapy failures since it most often goes undetected by conventional antimicrobial susceptibility tests. This study utilizes population analysis profiling (PAP) and time\u2013kill assay for the detection of heteroresistance in K. pneumoniae and for evaluating the association between in vitro regrowth and heteroresistance. The mechanisms of colistin resistance and the ability of combination therapies to suppress resistance selection were also analysed. In total, 3 (18%) of the 16 colistin-susceptible strains (MIC \u2264 2 mg\/L) were confirmed to be heteroresistant to colistin by PAP assay. In contrast to the colistin-susceptible control strains, all three heteroresistant strains showed regrowth when exposed to colistin after 24 h following a rapid bactericidal action. Colistin resistance in all the resistant subpopulations was due to the disruption of the mgrB gene by various insertion elements such as ISKpn14 of the IS1 family and IS903B of the IS5 family. Colistin combined with carbapenems (imipenem, meropenem), aminoglycosides (amikacin, gentamicin) or tigecycline was found to elicit in vitro synergistic effects against these colistin heteroresistant strains. Our experimental results showcase the potential of combination therapies for treatment of K. pneumoniae infections associated with colistin heteroresistance.<\/jats:p>","DOI":"10.3390\/genes14071426","type":"journal-article","created":{"date-parts":[[2023,7,11]],"date-time":"2023-07-11T01:40:02Z","timestamp":1689039602000},"page":"1426","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Insight into Antibiotic Synergy Combinations for Eliminating Colistin Heteroresistant Klebsiella pneumoniae"],"prefix":"10.3390","volume":"14","author":[{"given":"Sahaya Glingston","family":"Rajakani","sequence":"first","affiliation":[{"name":"Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, 2610 Antwerp, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5897-0240","authenticated-orcid":false,"given":"Basil Britto","family":"Xavier","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, 2610 Antwerp, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-3598-9261","authenticated-orcid":false,"given":"Adwoa","family":"Sey","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, 2610 Antwerp, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"El Bounja","family":"Mariem","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, 2610 Antwerp, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9424-3107","authenticated-orcid":false,"given":"Christine","family":"Lammens","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, 2610 Antwerp, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Herman","family":"Goossens","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, 2610 Antwerp, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Youri","family":"Glupczynski","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, 2610 Antwerp, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Surbhi","family":"Malhotra-Kumar","sequence":"additional","affiliation":[{"name":"Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, 2610 Antwerp, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,7,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/s12941-019-0343-8","article-title":"Klebsiella pneumoniae: An increasing threat to public health","volume":"19","author":"Effah","year":"2020","journal-title":"Ann. Clin. Microbiol. Antimicrob."},{"key":"ref_2","first-page":"427","article-title":"Colistin Treatment for Multidrug-Resistant Gram-Negative Infections in Children: Caution Required for Nephrotoxicity","volume":"56","author":"Ustundag","year":"2022","journal-title":"Sisli. Etfal Hastan Tip. Bul."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"268","DOI":"10.1111\/j.1469-0691.2011.03570.x","article-title":"Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: An international expert proposal for interim standard definitions for acquired resistance","volume":"18","author":"Magiorakos","year":"2012","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1097\/IM9.0000000000000002","article-title":"Acquired Resistance to Colistin via Chromosomal And Plasmid-Mediated Mechanisms in Klebsiella pneumoniae","volume":"1","author":"Berglund","year":"2019","journal-title":"Infect. Microbes Dis."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"868","DOI":"10.1080\/22221751.2020.1754133","article-title":"Colistin and its role in the Era of antibiotic resistance: An extended review (2000\u20132019)","volume":"9","author":"Zhong","year":"2020","journal-title":"Emerg. Microbes Infect."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1128\/CMR.00064-16","article-title":"Polymyxins: Antibacterial Activity, Susceptibility Testing, and Resistance Mechanisms Encoded by Plasmids or Chromosomes","volume":"30","author":"Poirel","year":"2017","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Band, V.I., and Weiss, D.S. (2019). Heteroresistance: A cause of unexplained antibiotic treatment failure?. PLoS Pathog., 15.","DOI":"10.1371\/journal.ppat.1007726"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"526","DOI":"10.1016\/j.ijantimicag.2016.11.029","article-title":"Resistance to polymyxins in Gram-negative organisms","volume":"49","author":"Jeannot","year":"2017","journal-title":"Int. J. Antimicrob. Agents"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e264","DOI":"10.1016\/S2666-5247(22)00387-1","article-title":"International manufacturing and trade in colistin, its implications in colistin resistance and One Health global policies: A microbiological, economic, and anthropological study","volume":"4","author":"Umair","year":"2023","journal-title":"Lancet Microbe"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"965","DOI":"10.2147\/IDR.S199844","article-title":"Molecular mechanisms related to colistin resistance in Enterobacteriaceae","volume":"12","author":"Aghapour","year":"2019","journal-title":"Infect. Drug Resist."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"392","DOI":"10.1016\/j.medin.2022.02.004","article-title":"Resistance mechanisms in Gram-negative bacteria","volume":"46","author":"Lepe","year":"2022","journal-title":"Med. Intensiv."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"e1262","DOI":"10.1002\/mbo3.1262","article-title":"Prevalence of insertion sequence elements in plasmids relating to mgrB gene disruption causing colistin resistance in Klebsiella pneumoniae","volume":"11","author":"Fordham","year":"2022","journal-title":"Microbiologyopen"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"5696","DOI":"10.1128\/AAC.03110-14","article-title":"MgrB Inactivation Is a Common Mechanism of Colistin Resistance in KPC-Producing Klebsiella pneumoniae of Clinical Origin","volume":"58","author":"Cannatelli","year":"2014","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"479","DOI":"10.1038\/s41579-019-0218-1","article-title":"Mechanisms and clinical relevance of bacterial heteroresistance","volume":"17","author":"Andersson","year":"2019","journal-title":"Nat. Rev. Genet."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"e01390-18","DOI":"10.1128\/JCM.01390-18","article-title":"Antimicrobial Susceptibility Testing for Polymyxins: Challenges, Issues, and Recommendations","volume":"57","author":"Ezadi","year":"2019","journal-title":"J. Clin. Microbiol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"946","DOI":"10.1093\/jac\/dkr007","article-title":"Colistin heteroresistance in carbapenemase-producing Klebsiella pneumoniae","volume":"66","author":"Meletis","year":"2011","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"320","DOI":"10.1016\/j.cmi.2022.10.018","article-title":"Antibiotic heteroresistance in ESKAPE pathogens, from bench to bedside","volume":"29","author":"Roch","year":"2022","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1128\/CMR.00058-14","article-title":"Antimicrobial Heteroresistance: An Emerging Field in Need of Clarity","volume":"28","author":"Valvano","year":"2015","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"4106","DOI":"10.1128\/JCM.02129-13","article-title":"Irreproducible and Uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes","volume":"51","author":"Landman","year":"2013","journal-title":"J. Clin. Microbiol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2097","DOI":"10.1093\/jac\/dkab122","article-title":"In vitro and in vivo synergistic effects of tigecycline combined with aminoglycosides on carbapenem-resistant Klebsiella pneumoniae","volume":"76","author":"Ni","year":"2021","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"e0015221","DOI":"10.1128\/Spectrum.00152-21","article-title":"Combined effect of Polymyxin B and Tigecycline to overcome Heteroresistance in Carbapenem-Resistant Klebsiella pneumoniae","volume":"9","author":"Tian","year":"2021","journal-title":"Microbiol. Spectr."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"868991","DOI":"10.3389\/fmicb.2022.868991","article-title":"Heteroresistance Is Associated With in vitro Regrowth During Colistin Treatment in Carbapenem-Resistant Klebsiella pneumoniae","volume":"13","author":"Wang","year":"2022","journal-title":"Front. Microbiol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1627","DOI":"10.1038\/s41564-019-0480-z","article-title":"Antibiotic combinations that exploit heteroresistance to multiple drugs effectively control infection","volume":"4","author":"Band","year":"2019","journal-title":"Nat. Microbiol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"6837","DOI":"10.1128\/AAC.01344-16","article-title":"Genomic Characterization of Colistin Heteroresistance in Klebsiella pneumoniae during a Nosocomial Outbreak","volume":"60","author":"Halaby","year":"2016","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1311","DOI":"10.1093\/jac\/dkn425","article-title":"In vitro pharmacodynamics of colistin against multidrug-resistant Klebsiella pneumoniae","volume":"62","author":"Poudyal","year":"2008","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1186\/s13054-020-2763-4","article-title":"Intrapulmonary concentrations of meropenem administered by continuous infusion in critically ill patients with nosocomial pneumonia: A randomized pharmacokinetic trial","volume":"24","author":"Luque","year":"2020","journal-title":"Crit. Care"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1007\/BF01646409","article-title":"Pharmacokinetics of imipenem in patients undergoing major colon surgery","volume":"18","author":"Erttmann","year":"1990","journal-title":"Infection"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1002\/phar.2209","article-title":"International Consensus Guidelines for the Optimal Use of the Polymyxins: Endorsed by the American College of Clinical Pharmacy (ACCP), European Society of Clinical Microbiology and Infectious Diseases (ESCMID), Infectious Diseases Society of America (IDSA), International Society for Anti-infective Pharmacology (ISAP), Society of Critical Care Medicine (SCCM), and Society of Infectious Diseases Pharmacists (SIDP)","volume":"39","author":"Tsuji","year":"2019","journal-title":"Pharmacotherapy"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Cheong, H.S., Kim, S.Y., Wi, Y.M., Peck, K.R., and Ko, K.S. (2019). Colistin Heteroresistance in Klebsiella Pneumoniae Isolates and Diverse Mutations of PmrAB and PhoPQ in Resistant Subpopulations. J. Clin. Med., 8.","DOI":"10.3390\/jcm8091444"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"590","DOI":"10.1007\/s12275-021-0610-1","article-title":"Detection of colistin-resistant populations prior to antibiotic exposure in KPC-2-producing Klebsiella pneumoniae clinical isolates","volume":"59","author":"Seo","year":"2021","journal-title":"J. Microbiol."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Morales-Le\u00f3n, F., Lima, C.A., Gonz\u00e1lez-Rocha, G., Opazo-Capurro, A., and Bello-Toledo, H. (2020). Colistin Heteroresistance among Extended Spectrum \u03b2-lactamases-Producing Klebsiella pneumoniae. Microorganisms, 8.","DOI":"10.3390\/microorganisms8091279"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"e00356-17","DOI":"10.1128\/AAC.00356-17","article-title":"Deciphering Heteroresistance to Colistin in a Klebsiella pneumoniae Isolate from Marseille, France","volume":"61","author":"Bardet","year":"2017","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1128\/mSystems.00783-20","article-title":"Emerging Transcriptional and Genomic Mechanisms Mediating Carbapenem and Polymyxin Resistance in Enterobacteriaceae: A Systematic Review of Current Reports","volume":"5","author":"Mmatli","year":"2020","journal-title":"mSystems"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1093\/jac\/dku323","article-title":"The mgrB gene as a key target for acquired resistance to colistin in Klebsiella pneumoniae","volume":"70","author":"Poirel","year":"2015","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1093\/cid\/ciac268","article-title":"Infectious Diseases Society of America 2022 Guidance on the Treatment of Extended-Spectrum \u03b2-lactamase Producing Enterobacterales (ESBL-E), Carbapenem-Resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with Difficult-to-Treat Resistance (DTR-P. aeruginosa)","volume":"75","author":"Tamma","year":"2022","journal-title":"Clin. Infect. Dis."}],"container-title":["Genes"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4425\/14\/7\/1426\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T20:10:15Z","timestamp":1760127015000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4425\/14\/7\/1426"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,7,10]]},"references-count":35,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2023,7]]}},"alternative-id":["genes14071426"],"URL":"https:\/\/doi.org\/10.3390\/genes14071426","relation":{},"ISSN":["2073-4425"],"issn-type":[{"value":"2073-4425","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,7,10]]}}}