{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T14:13:30Z","timestamp":1790777610479,"version":"4.1.0"},"reference-count":58,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2022,12,9]],"date-time":"2022-12-09T00:00:00Z","timestamp":1670544000000},"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":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Enterobacter bugandensis is an emerging human pathogen in which multidrug resistant strains have been continuously isolated from various environments. Thus, this organism possesses the potential to pose challenges in human healthcare. However, the mechanisms, especially the efflux pumps, responsible for the multidrug resistance in E. bugandensis remain to be well elucidated.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>The Enterobacter strain CMCC(B) 45301 was specifically identified using whole genome sequencing. The specific CMCC(B) 45301 homologues of the TolC dependent efflux-pump genes characterized in Escherichia coli were identified. The tolC deletion mutant in CMCC(B) 45301 was constructed and subjected to susceptibility tests using 26 different antimicrobial agents, along with the wild type strain. The synergistic effects combining the Bacillus crude extract (BCE) and several other TolC-affected compounds against CMCC(B) 45301 were assayed.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>We reclassified the Enterobacter CMCC(B) 45301 strain from species cloacae to bugandensis, on the basis of its whole genome sequence. We found that the CMCC(B) 45301 TolC, AcrAB, AcrD, AcrEF, MdtABC, EmrAB, and MacAB exhibit high similarity with their respective homologues in E. coli and Enterobacter cloacae. Our results for the susceptibility tests revealed that lacking tolC causes 4- to 256-fold decrease in the minimal inhibitory concentrations of piperacillin, gentamicin, kanamycin, tetracycline, norfloxacin, ciprofloxacin, chloramphenicol, and erythromycin against CMCC(B) 45301. In addition, the inhibition zones formed by cefuroxime, cefoperazone, amikacin, streptomycin, minocycline, doxycycline, levofloxacin, florfenicol, trimethoprim-sulfamethoxazole, azithromycin, lincomycin, and clindamycin for the tolC mutant were larger or more obvious than that for the parent. Our data suggested the important role played by TolC in CMCC(B) 45301 susceptibility to common antibiotic families covering \u00df-lactam, aminoglycoside, tetracycline, fluoroquinolone, phenicol, folate pathway antagonist, macrolide, and lincosamide. Deletion for tolC also increased the susceptibility of CMCC(B) 45301 to berberine hydrochloride and BCE, two natural product-based agents. Finally, we found that erythromycin, norfloxacin, and ciprofloxacin can potentiate the antibacterial activity of BCE against CMCC(B) 45301.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>The present study elaborated the comprehensive TolC effect on the antimicrobial susceptibility profile in E. bugandensis, which might contribute to the development of more therapeutic options against this nosocomial pathogen.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fcimb.2022.1036933","type":"journal-article","created":{"date-parts":[[2022,12,9]],"date-time":"2022-12-09T02:47:48Z","timestamp":1670554068000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":7,"title":["A comprehensive description of the TolC effect on the antimicrobial susceptibility profile in Enterobacter bugandensis"],"prefix":"10.3389","volume":"12","author":[{"given":"Bingyu","family":"Li","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ji","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaodong","family":"Li","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2022,12,9]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2019.00044","article-title":"Multidrug-resistant enterobacter cloacae complex emerging as a global, diversifying threat","volume":"10","author":"Annavajhala","year":"2019","journal-title":"Front. Microbiol."},{"key":"B2","doi-asserted-by":"publisher","first-page":"2159","DOI":"10.1093\/nar\/gky066","article-title":"Single molecule real-time (Smrt) sequencing comes of age: Applications and utilities for medical diagnostics","volume":"46","author":"Ardui","year":"2018","journal-title":"Nucleic Acids Res."},{"key":"B3","doi-asserted-by":"publisher","first-page":"164","DOI":"10.1007\/s12602-014-9183-1","article-title":"The natural antimicrobial subtilosin a synergizes with lauramide arginine ethyl ester (Lae), epsilon-Poly-L-Lysine (Polylysine), clindamycin phosphate and metronidazole, against the vaginal pathogen gardnerella vaginalis","volume":"7","author":"Cavera","year":"2015","journal-title":"Probiotics Antimicrob. Proteins"},{"key":"B4","doi-asserted-by":"publisher","first-page":"329","DOI":"10.1007\/s00253-021-11632-0","article-title":"Bacillibactin class of siderophore antibiotics from a marine symbiotic bacillus as promising antibacterial agents","volume":"106","author":"Chakraborty","year":"2022","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"B5","doi-asserted-by":"publisher","first-page":"1141","DOI":"10.1128\/jb.134.3.1141-1156.1978","article-title":"Construction and characterization of amplifiable multicopy dna cloning vehicles derived from the P15a cryptic miniplasmid","volume":"134","author":"Chang","year":"1978","journal-title":"J. Bacteriol."},{"key":"B6","doi-asserted-by":"publisher","first-page":"488","DOI":"10.1179\/joc.2007.19.5.488","article-title":"Characterization of fluoroquinolone resistance mechanisms and their correlation with the degree of resistance to clinically used fluoroquinolones among escherichia coli isolates","volume":"19","author":"Chang","year":"2007","journal-title":"J. Chemother."},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1128\/mBio.02093-16","article-title":"Comprehensive genome analysis of carbapenemase-producing enterobacter spp.: New insights into phylogeny, population structure, and resistance mechanisms","volume":"7","author":"Chavda","year":"2016","journal-title":"Mbio"},{"key":"B8","doi-asserted-by":"publisher","first-page":"585","DOI":"10.7326\/0003-4819-115-8-585","article-title":"Enterobacter bacteremia: Clinical features and emergence of antibiotic resistance during therapy","volume":"115","author":"Chow","year":"1991","journal-title":"Ann. Intern. Med."},{"key":"B9","doi-asserted-by":"publisher","first-page":"2386","DOI":"10.1099\/ijsem.0.002809","article-title":"Using average nucleotide identity to improve taxonomic assignments in prokaryotic genomes At the ncbi","volume":"68","author":"Ciufo","year":"2018","journal-title":"Int. J. Syst. Evol. Microbiol."},{"key":"B10","volume-title":"Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically CLSI standard M07","year":"2018"},{"key":"B11","volume-title":"Performance standards for antimicrobial disk susceptibility tests CLSI standard M02","year":"2018"},{"key":"B12","volume-title":"Performance standards for antimicrobial susceptibility testing CLSI supplement M100","year":"2022"},{"key":"B13","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2015.00392","article-title":"Enterobacter aerogenes and enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment","volume":"6","author":"Davin-Regli","year":"2015","journal-title":"Front. Microbiol."},{"key":"B14","doi-asserted-by":"publisher","first-page":"474","DOI":"10.1007\/s13205-020-02459-z","article-title":"Bacillus subtilis Tr47ii as a source of bioactive lipopeptides against gram-negative pathogens causing nosocomial infections","volume":"10","author":"de Souza Freitas","year":"2020","journal-title":"3 Biotech."},{"key":"B15","doi-asserted-by":"publisher","first-page":"968","DOI":"10.1099\/ijsem.0.000821","article-title":"Enterobacter bugandensis sp. nov., isolated from neonatal blood","volume":"66","author":"Doijad","year":"2016","journal-title":"Int. J. Syst. Evol. Microbiol."},{"key":"B16","doi-asserted-by":"publisher","first-page":"149","DOI":"10.1016\/S0378-1119(97)00619-7","article-title":"Improved allelic exchange vectors and their use to analyze 987p fimbria gene expression","volume":"207","author":"Edwards","year":"1998","journal-title":"Gene"},{"key":"B17","doi-asserted-by":"publisher","first-page":"e0215622","DOI":"10.1128\/spectrum.02156-22","article-title":"Impact of bacillus subtilis antibiotic bacilysin and campylobacter jejuni efflux pumps on pathogen survival in mixed biofilms","volume":"10","author":"Erega","year":"2022","journal-title":"Microbiol. Spectr."},{"key":"B18","doi-asserted-by":"publisher","DOI":"10.1128\/MRA.00465-19","article-title":"Whole-genome sequences of clinical enterobacter bugandensis isolates from Germany","volume":"8","author":"Falgenhauer","year":"2019","journal-title":"Microbiol. Resour. Announc."},{"key":"B19","doi-asserted-by":"publisher","first-page":"15","DOI":"10.1186\/s40793-016-0134-1","article-title":"Meeting report: Genbank microbial genomic taxonomy workshop (12\u201313 may 2015)","volume":"11","author":"Federhen","year":"2016","journal-title":"Stand Genom. Sci."},{"key":"B20","doi-asserted-by":"publisher","first-page":"173","DOI":"10.1053\/jhin.2001.1053","article-title":"Molecular epidemiological typing of enterobacter cloacae isolates from a neonatal intensive care unit: Three-year prospective study","volume":"49","author":"Fernandez-Baca","year":"2001","journal-title":"J. Hosp. Infect."},{"key":"B21","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.00962-20","article-title":"Ramr deletion in an enterobacter hormaechei isolate as a consequence of therapeutic failure of key antibiotics in a long-term hospitalized patient","volume":"64","author":"Gravey","year":"2020","journal-title":"Antimicrob. Agents Chemother."},{"key":"B22","doi-asserted-by":"publisher","DOI":"10.1128\/mBio.00465-20","article-title":"Chlorpromazine and amitriptyline are substrates and inhibitors of the acrb multidrug efflux pump","volume":"11","author":"Grimsey","year":"2020","journal-title":"Mbio"},{"key":"B23","doi-asserted-by":"publisher","first-page":"2373","DOI":"10.1128\/AAC.02840-15","article-title":"Landscape of resistance-Nodulation-Cell division (Rnd)-type efflux pumps in enterobacter cloacae complex","volume":"60","author":"Guerin","year":"2016","journal-title":"Antimicrob. Agents Chemother."},{"key":"B24","doi-asserted-by":"publisher","first-page":"236","DOI":"10.1016\/j.ijantimicag.2012.10.022","article-title":"Characterisation and clinical features of enterobacter cloacae bloodstream infections occurring At a tertiary care university hospital in Switzerland: Is cefepime adequate therapy","volume":"41","author":"Hilty","year":"2013","journal-title":"Int. J. Antimicrob. Agents"},{"key":"B25","doi-asserted-by":"publisher","first-page":"2551","DOI":"10.1093\/jac\/dkz236","article-title":"Heterogeneous resistance to colistin in enterobacter cloacae complex due to a new small transmembrane protein","volume":"74","author":"Huang","year":"2019","journal-title":"J. Antimicrob. Chemother."},{"key":"B26","doi-asserted-by":"publisher","first-page":"5639","DOI":"10.1128\/JB.183.19.5639-5644.2001","article-title":"Novel macrolide-specific abc-type efflux transporter in escherichia coli","volume":"183","author":"Kobayashi","year":"2001","journal-title":"J. Bacteriol."},{"key":"B27","doi-asserted-by":"publisher","first-page":"1749","DOI":"10.1128\/AAC.01533-09","article-title":"Efflux pumps are involved in the defense of gram-negative bacteria against the natural products isobavachalcone and diospyrone","volume":"54","author":"Kuete","year":"2010","journal-title":"Antimicrob. Agents Chemother."},{"key":"B28","doi-asserted-by":"publisher","first-page":"170533","DOI":"10.1016\/j.peptides.2021.170533","article-title":"Sublancin protects against methicillin-resistant staphylococcus aureus infection by the combined modulation of innate immune response and microbiota","volume":"141","author":"Li","year":"2021","journal-title":"Peptides"},{"key":"B29","doi-asserted-by":"publisher","first-page":"1657","DOI":"10.1159\/000479411","article-title":"Synergistic activity of berberine with azithromycin against pseudomonas aeruginosa isolated from patients with cystic fibrosis of lung In vitro and In vivo","volume":"42","author":"Li","year":"2017","journal-title":"Cell Physiol. Biochem."},{"key":"B30","doi-asserted-by":"publisher","first-page":"337","DOI":"10.1128\/CMR.00117-14","article-title":"The challenge of efflux-mediated antibiotic resistance in gram-negative bacteria","volume":"28","author":"Li","year":"2015","journal-title":"Clin. Microbiol. Rev."},{"key":"B31","doi-asserted-by":"publisher","DOI":"10.3389\/fcimb.2021.660431","article-title":"A potential combination therapy of berberine hydrochloride with antibiotics against multidrug-resistant acinetobacter baumannii","volume":"11","author":"Li","year":"2021","journal-title":"Front. Cell Infect. Microbiol."},{"key":"B32","doi-asserted-by":"publisher","first-page":"208","DOI":"10.1186\/s12866-021-02250-x","article-title":"Characterization of resistance mechanisms of enterobacter cloacae complex Co-resistant to carbapenem and colistin","volume":"21","author":"Liu","year":"2021","journal-title":"BMC Microbiol."},{"key":"B33","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0222413","article-title":"Sensitization of avian pathogenic escherichia coli to amoxicillin In vitro and In vivo in the presence of surfactin","volume":"14","author":"Liu","year":"2019","journal-title":"PloS One"},{"key":"B34","first-page":"355","article-title":"Mechanisms of resistance in clinical isolates of enterobacter cloacae that are less susceptible to cefepime than to ceftazidime","volume":"48","author":"Liu","year":"2018","journal-title":"Ann. Clin. Lab. Sci."},{"key":"B35","doi-asserted-by":"publisher","first-page":"3104613","DOI":"10.1155\/2020\/3104613","article-title":"Mechanism of antibacterial activity of bacillus amyloliquefaciens c-1 lipopeptide toward anaerobic clostridium difficile","volume":"2020","author":"Lv","year":"2020","journal-title":"BioMed. Res. Int."},{"key":"B36","doi-asserted-by":"publisher","first-page":"458","DOI":"10.1038\/s41467-018-02875-z","article-title":"Overcoming mcr-1 mediated colistin resistance with colistin in combination with other antibiotics","volume":"9","author":"MacNair","year":"2018","journal-title":"Nat. Commun."},{"key":"B37","doi-asserted-by":"publisher","first-page":"1182","DOI":"10.1016\/j.ygeno.2019.07.003","article-title":"Population structure and pangenome analysis of enterobacter bugandensis uncover the presence of blactx-M-55, blandm-5 and blaimi-1, along with sophisticated iron acquisition strategies","volume":"112","author":"Matteoli","year":"2020","journal-title":"Genomics"},{"key":"B38","doi-asserted-by":"publisher","first-page":"887","DOI":"10.2217\/fmb.12.61","article-title":"Enterobacter cloacae complex: Clinical impact and emerging antibiotic resistance","volume":"7","author":"Mezzatesta","year":"2012","journal-title":"Future Microbiol."},{"key":"B39","doi-asserted-by":"publisher","first-page":"264","DOI":"10.1016\/j.jgar.2021.07.013","article-title":"Isolation and characterisation of carbapenemase-producing and polymyxin b-resistant enterobacter bugandensis from a vegetable","volume":"26","author":"Moon","year":"2021","journal-title":"J. Glob. Antimicrob. Resist."},{"key":"B40","doi-asserted-by":"publisher","first-page":"2145176","DOI":"10.1155\/2021\/2145176","article-title":"Detection of oqxab efflux pumps, a multidrug-resistant agent in bacterial infection in patients referring to teaching hospitals in ahvaz, southwest of Iran","volume":"2021","author":"Moosavian","year":"2021","journal-title":"Int. J. Microbiol."},{"key":"B41","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2016.01223","article-title":"Berberine is a novel type efflux inhibitor which attenuates the mexxy-mediated aminoglycoside resistance in pseudomonas aeruginosa","volume":"7","author":"Morita","year":"2016","journal-title":"Front. Microbiol."},{"key":"B42","doi-asserted-by":"publisher","first-page":"4161","DOI":"10.1128\/JB.184.15.4161-4167.2002","article-title":"The putative response regulator baer stimulates multidrug resistance of escherichia coli Via a novel multidrug exporter system, mdtabc","volume":"184","author":"Nagakubo","year":"2002","journal-title":"J. Bacteriol."},{"key":"B43","doi-asserted-by":"publisher","first-page":"529","DOI":"10.1097\/00001432-199912000-00001","article-title":"Antibiotic efflux mechanisms","volume":"12","author":"Nikaido","year":"1999","journal-title":"Curr. Opin. Infect. Dis."},{"key":"B44","doi-asserted-by":"publisher","first-page":"3030","DOI":"10.1128\/AAC.47.9.3030-3033.2003","article-title":"Roles of tolc-dependent multidrug transporters of escherichia coli in resistance to beta-lactams","volume":"47","author":"Nishino","year":"2003","journal-title":"Antimicrob. Agents Chemother."},{"key":"B45","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2021.737288","article-title":"Function and inhibitory mechanisms of multidrug efflux pumps","volume":"12","author":"Nishino","year":"2021","journal-title":"Front. Microbiol."},{"key":"B46","doi-asserted-by":"publisher","first-page":"5392","DOI":"10.1038\/s41598-018-23069-z","article-title":"Enterobacter bugandensis: A novel enterobacterial species associated with severe clinical infection","volume":"8","author":"Pati","year":"2018","journal-title":"Sci. Rep."},{"key":"B47","doi-asserted-by":"publisher","first-page":"3247","DOI":"10.1128\/AAC.00072-07","article-title":"Cloning, nucleotide sequencing, and analysis of the acrab-tolc efflux pump of enterobacter cloacae and determination of its involvement in antibiotic resistance in a clinical isolate","volume":"51","author":"Perez","year":"2007","journal-title":"Antimicrob. Agents Chemother."},{"key":"B48","doi-asserted-by":"publisher","first-page":"3","DOI":"10.1038\/s41525-017-0042-3","article-title":"Cytogenomic identification and long-read single molecule real-time (Smrt) sequencing of a bardet-biedl syndrome 9 (Bbs9) deletion","volume":"3","author":"Reiner","year":"2018","journal-title":"NPJ Genom. Med."},{"key":"B49","doi-asserted-by":"publisher","first-page":"220","DOI":"10.1128\/CMR.10.2.220","article-title":"Enterobacter spp.: Pathogens poised to flourish At the turn of the century","volume":"10","author":"Sanders","year":"1997","journal-title":"Clin. Microbiol. Rev."},{"key":"B50","doi-asserted-by":"publisher","first-page":"41","DOI":"10.7883\/yoken.JJID.2021.141","article-title":"Molecular epidemiology of enterobacter cloacae complex isolates with reduced carbapenem susceptibility recovered by blood culture","volume":"75","author":"Sarangi","year":"2022","journal-title":"Jpn J. Infect. Dis."},{"key":"B51","doi-asserted-by":"publisher","first-page":"1842","DOI":"10.1128\/JB.01474-14","article-title":"Amylocyclicin, a novel circular bacteriocin produced by bacillus amyloliquefaciens Fzb42","volume":"196","author":"Scholz","year":"2014","journal-title":"J. Bacteriol."},{"key":"B52","doi-asserted-by":"publisher","first-page":"115511","DOI":"10.1016\/j.diagmicrobio.2021.115511","article-title":"Comparative genomics of enterobacter cloacae complex before and after acquired clinical resistance to ceftazidime-avibactam","volume":"101","author":"Senchyna","year":"2021","journal-title":"Diagn. Microbiol. Infect. Dis."},{"key":"B53","doi-asserted-by":"publisher","first-page":"175","DOI":"10.1186\/s12866-018-1325-2","article-title":"Multi-drug resistant enterobacter bugandensis species isolated from the international space station and comparative genomic analyses with human pathogenic strains","volume":"18","author":"Singh","year":"2018","journal-title":"BMC Microbiol."},{"key":"B54","doi-asserted-by":"publisher","first-page":"2715","DOI":"10.1093\/jac\/dkx215","article-title":"Soxrs induces colistin hetero-resistance in enterobacter asburiae and enterobacter cloacae by regulating the acrab-tolc efflux pump","volume":"72","author":"Telke","year":"2017","journal-title":"J. Antimicrob. Chemother."},{"key":"B55","doi-asserted-by":"publisher","first-page":"43","DOI":"10.1007\/7651_2014_182","article-title":"Splicing by overlap extension pcr to obtain hybrid dna products","volume":"1373","author":"Thornton","year":"2016","journal-title":"Methods Mol. Biol."},{"key":"B56","doi-asserted-by":"publisher","first-page":"1682","DOI":"10.7164\/antibiotics.40.1682","article-title":"Difficidin and oxydifficidin: Novel broad spectrum antibacterial antibiotics produced by bacillus subtilis. ii. isolation and physico-chemical characterization","volume":"40","author":"Wilson","year":"1987","journal-title":"J. Antibiot. (Tokyo)"},{"key":"B57","doi-asserted-by":"publisher","first-page":"183488","DOI":"10.1016\/j.bbamem.2020.183488","article-title":"Structural characterization of the emrab-tolc efflux complex from e. coli","volume":"1863","author":"Yousefian","year":"2021","journal-title":"Biochim. Biophys. Acta Biomembr."},{"key":"B58","doi-asserted-by":"publisher","DOI":"10.3389\/fcimb.2022.815436","article-title":"Comparative study of bacillus amyloliquefaciens X030 on the intestinal flora and antibacterial activity against aeromonas of grass carp","volume":"12","author":"Zhou","year":"2022","journal-title":"Front. Cell Infect. Microbiol."}],"container-title":["Frontiers in Cellular and Infection Microbiology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fcimb.2022.1036933\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,12,9]],"date-time":"2022-12-09T02:47:52Z","timestamp":1670554072000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fcimb.2022.1036933\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,12,9]]},"references-count":58,"alternative-id":["10.3389\/fcimb.2022.1036933"],"URL":"https:\/\/doi.org\/10.3389\/fcimb.2022.1036933","relation":{},"ISSN":["2235-2988"],"issn-type":[{"value":"2235-2988","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,12,9]]},"article-number":"1036933"}}