{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,31]],"date-time":"2026-01-31T06:01:21Z","timestamp":1769839281578,"version":"3.49.0"},"reference-count":50,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2013,11,7]],"date-time":"2013-11-07T00:00:00Z","timestamp":1383782400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Klebsiella pneumoniae is one of the most common Gram-negative bacterial pathogens in clinical practice. It is associated with a wide range of disorders, ranging from superficial skin and soft tissue infections to potentially fatal sepsis in the lungs and  blood stream. Quorum sensing, or bacterial cell-cell communication, refers to population  density-dependent gene expression modulation. Quorum sensing in Proteobacteria relies on the production and sensing of signaling molecules which are mostly N-acylhomoserine lactones. Here, we report the identification of a multidrug resistant clinical isolate,  K. pneumoniae strain CSG20, using matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. We further confirmed quorum sensing activity in this strain with the use of high resolution tandem liquid chromatography quadrupole  mass spectrometry and provided evidence K. pneumoniae strain CSG20 produced  N-hexanoyl-homoserine lactone (C6-HSL). To the best of our knowledge, this is the first report on the production of N-hexanoylhomoserine lactone (C6-HSL) in clinical isolate  K. pneumoniae.<\/jats:p>","DOI":"10.3390\/s131115242","type":"journal-article","created":{"date-parts":[[2013,11,7]],"date-time":"2013-11-07T15:28:06Z","timestamp":1383838086000},"page":"15242-15251","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Short Chain N-Acylhomoserine Lactone Production by Clinical Multidrug Resistant Klebsiella pneumoniae Strain CSG20"],"prefix":"10.3390","volume":"13","author":[{"given":"Yun","family":"Ngeow","sequence":"first","affiliation":[{"name":"Department of Medical Microbiology, Faculty of Medicine, University of Malaya,  Kuala Lumpur 50603, Malaysia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Huey","family":"Cheng","sequence":"additional","affiliation":[{"name":"Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jian","family":"Chen","sequence":"additional","affiliation":[{"name":"Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wai-Fong","family":"Yin","sequence":"additional","affiliation":[{"name":"Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1883-1115","authenticated-orcid":false,"given":"Kok-Gan","family":"Chan","sequence":"additional","affiliation":[{"name":"Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2013,11,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"589","DOI":"10.1128\/CMR.11.4.589","article-title":"Klebsiella spp. as nosocomial pathogens: Epidemiology, taxonomy, typing methods, and pathogenicity factors","volume":"11","author":"Podschun","year":"1998","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_2","unstructured":"Guentzel, M.N. (1996). Medical Microbiology, Galveston (TX). [4th ed.]."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"160","DOI":"10.3201\/eid0802.010025","article-title":"Community-acquired Klebsiella pneumoniae bacteremia: Global differences in clinical patterns","volume":"8","author":"Ko","year":"2002","journal-title":"Emerg. Infect. Dis."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"748","DOI":"10.1111\/j.1463-1318.2006.01028.x","article-title":"Life-threatening sepsis following treatment for haemorrhoids: A systematic review","volume":"8","author":"McCloud","year":"2006","journal-title":"Colorectal Dis."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"214","DOI":"10.1378\/chest.107.1.214","article-title":"Rapidly fatal outcome of bacteremic Klebsiella pneumoniae pneumonia in alcoholics","volume":"107","author":"Jong","year":"1995","journal-title":"Chest. J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"697","DOI":"10.1084\/jem.20030857","article-title":"A novel virulence gene in Klebsiella pneumoniae strains causing primary liver abscess and septic metastatic complications","volume":"199","author":"Fang","year":"2004","journal-title":"J. Exp. Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1186\/1471-2334-10-307","article-title":"Bacteremic community-acquired pneumonia due to Klebsiella pneumoniae: Clinical and microbiological characteristics in Taiwan, 2001\u20132008","volume":"10","author":"Lin","year":"2010","journal-title":"BMC Infect. Dis."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"359","DOI":"10.1146\/annurev-med-081210-144458","article-title":"Crisis in hospital-acquired, healthcare-associated infections","volume":"63","author":"Calfee","year":"2012","journal-title":"Annu. Rev. Med."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1119","DOI":"10.1093\/jac\/dkq108","article-title":"Detection and treatment options for Klebsiella pneumoniae carbapenemases (KPCs): An emerging cause of multidrug-resistant infection","volume":"65","author":"Hirsch","year":"2010","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"689","DOI":"10.1093\/jac\/dkq520","article-title":"Does broad-spectrum \u03b2-lactam resistance due to NDM-1 herald the end of the antibiotic era for treatment of infections caused by Gram-negative bacteria?","volume":"66","author":"Nordmann","year":"2011","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"779","DOI":"10.1007\/s00134-012-2811-x","article-title":"Adding risk factors for potentially resistant pathogens, increasing antibiotic pressure and risk creating the \u201cuntreatable bacteria\u201d: Time to change direction","volume":"39","author":"Paiva","year":"2013","journal-title":"Intensiv. Care Med."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"2314","DOI":"10.1074\/jbc.M112.430199","article-title":"Evolution of broad spectrum \u03b2-lactam resistance in an engineered metallo-\u03b2-lactamase","volume":"288","author":"Sun","year":"2013","journal-title":"J. Biol. Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1146\/annurev.micro.55.1.165","article-title":"Quorum sensing in bacteria","volume":"55","author":"Miller","year":"2001","journal-title":"Annu. Rev. Microbiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"6384","DOI":"10.1128\/JB.180.23.6384-6388.1998","article-title":"N-acyl-L-homoserine lactone autoinducers control production of an extracellular lipopeptide biosurfactant required for swarming motility of Serratia liquefaciens MG1","volume":"180","author":"Lindum","year":"1998","journal-title":"J. Bacteriol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1087","DOI":"10.2217\/fmb.10.68","article-title":"Social interactions in the Burkholderia cepacia complex: Biofilms and quorum sensing","volume":"5","author":"Coenye","year":"2010","journal-title":"Future Microbiol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"595","DOI":"10.1016\/j.resmic.2010.05.014","article-title":"Quorum sensing affects biofilm formation through lipopolysaccharde synthesis in Klebsiella pneumoniae","volume":"161","author":"Balestrino","year":"2010","journal-title":"Res. Microbiol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1039\/b804469b","article-title":"Quorum sensing and bacterial biofilms","volume":"27","author":"Dickschat","year":"2010","journal-title":"Nat. Prod. Rep."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1073\/pnas.0408639102","article-title":"Revisiting quorum sensing: Discovery of additional chemical and biological functions for 3-oxo-N-acylhomoserine lactones","volume":"102","author":"Kaufmann","year":"2005","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3703","DOI":"10.1099\/00221287-143-12-3703","article-title":"Quorum sensing and Chromobacterium violaceum: Exploitation of violacein production and inhibition for the detection of N-acylhomoserine lactones","volume":"143","author":"McClean","year":"1997","journal-title":"Microbiology"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"13217","DOI":"10.3390\/s131013217","article-title":"Short chain N-acyl homoserine lactone production by soil isolate Burkholderia sp. strain A9","volume":"13","author":"Chen","year":"2013","journal-title":"Sensors"},{"key":"ref_21","unstructured":"(2008). MALDI Biotyper User Manual 2008, Version 20 SR1, Bruker Daltonic Inc."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"5271","DOI":"10.1128\/jb.179.17.5271-5281.1997","article-title":"Quorum sensing in Aeromonas hydrophila and Aeromonas salmonicida: Identification of the LuxRI homologs AhyRI and AsaRI and their cognate N-acylhomoserine lactone signal molecules","volume":"179","author":"Swift","year":"1997","journal-title":"J. Bacteriol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"541","DOI":"10.1099\/13500872-141-3-541","article-title":"Carbapenem antibiotic production in Erwinia carotovora is regulated by CarR, a homologue of the LuxR transcriptional activator","volume":"141","author":"McGowan","year":"1995","journal-title":"Microbiology"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Chan, K.G., Atkinson, S., Mathee, K., Sam, C.K., Chhabra, S.R., C\u00e1mara, M., Koh, C.L., and Williams, P. (2011). Characterization of N-acylhomoserine lactone-degrading bacteria associated with the Zingiber officinale(ginger) rhizosphere: Co-existence of quorum quenching and quorum sensing in Acinetobacter and Burkholderia. BMC Microbiol., 11.","DOI":"10.1186\/1471-2180-11-51"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1007\/s11274-011-0836-x","article-title":"Coexistence of quorum-quenching and quorum-sensing in tropical marine Pseudomonas aeruginosa strain MW3A","volume":"28","author":"Wong","year":"2011","journal-title":"World J. Microbiol. Biotechnol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"5635","DOI":"10.1128\/IAI.70.10.5635-5646.2002","article-title":"N-acylhomoserine lactones undergo lactonolysis in a pH-, temperature-, and acyl chain length-dependent manner during growth of Yersinia pseudotuberculoxis and Pseudomonas aeruginosa","volume":"70","author":"Yates","year":"2002","journal-title":"Infect. Immun."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Maier, T., Klepel, S., Renner, U., and Kostrzewa, M. (2006). Fast and reliable maldi-tof ms\u2013based microorganism identification. Nat. Methods.","DOI":"10.1038\/nmeth870"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"176","DOI":"10.1128\/JCM.05742-11","article-title":"Direct MALDI-TOF mass spectrometry assay of blood culture broths for rapid identification of Candida species causing bloodstream infections: An observational study in two large microbiology laboratories","volume":"50","author":"Spanu","year":"2012","journal-title":"J. Clin. Microbiol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1905","DOI":"10.1007\/s00216-011-4877-7","article-title":"Use of the MALDI BioTyper system with MALDI-TOF mass spectrometry for rapid identification of microorganisms","volume":"400","author":"Sogawa","year":"2011","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1146\/annurev.genet.35.102401.090913","article-title":"Regulation of gene expression by cell-to-cell communication: Acyl-homoserine lactone quorum sensing","volume":"35","author":"Fuqua","year":"2001","journal-title":"Annu. Rev. Genet."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"685","DOI":"10.1038\/nrm907","article-title":"Listening in on bacteria: Acyl-homoserine lactone signalling","volume":"3","author":"Fuqua","year":"2002","journal-title":"Nat. Rev. Mol. Cell Biol."},{"key":"ref_32","first-page":"1268","article-title":"Cell-cell interactions in bacterial populations","volume":"69","author":"Voloshin","year":"2004","journal-title":"Biochem. (Mosc.)"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"4666","DOI":"10.1128\/AEM.68.9.4666-4671.2002","article-title":"Quorum sensing and production of autoinducer-2 in Campylobacter spp., Escherichia coli O157:H7, and Salmonella enterica serovar Typhimurium in foods","volume":"68","author":"Cloak","year":"2002","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1291","DOI":"10.1172\/JCI20195","article-title":"Interspecies communication in bacteria","volume":"112","author":"Federle","year":"2003","journal-title":"J. Clin. Investig."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"21670","DOI":"10.1016\/S0021-9258(20)88238-6","article-title":"Purification and structural identification of an autoinducer for the luminescence system of Vibrio harveyi","volume":"264","author":"Cao","year":"1989","journal-title":"J. Biol. Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"2870","DOI":"10.1128\/JB.187.8.2870-2880.2005","article-title":"Characterization of type 2 quorum sensing in Klebsiella pneumoniae and relationship with biofilm formation","volume":"187","author":"Balestrino","year":"2005","journal-title":"J. Bacteriol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1754","DOI":"10.1128\/AEM.68.4.1754-1759.2002","article-title":"Identification of quorum quenching N-acyl homoserine lactonases from Bacillus species","volume":"68","author":"Dong","year":"2002","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"17606","DOI":"10.1073\/pnas.0504996102","article-title":"The molecular structure and catalytic mechanism of a quorum-quenching N-acyl-L-homoserine lactone hydrolase","volume":"102","author":"Kim","year":"2005","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1201","DOI":"10.1098\/rstb.2007.2045","article-title":"Quorum-quenching microbial infections: Mechanisms and implications","volume":"362","author":"Dong","year":"2007","journal-title":"Philos. Trans. R. Soc. B"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1007\/s10482-010-9438-0","article-title":"Rapid degradation of N-3-oxoacylhomoserine lactones by a Bacillus cereus isolate from Malaysian rainforest soil","volume":"98","author":"Chan","year":"2010","journal-title":"Antonie van Leeuwenhoek"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"4661","DOI":"10.3390\/s120404661","article-title":"Quorum quenching revisited\u2014From signal decay to signalling confusion","volume":"12","author":"Hong","year":"2012","journal-title":"Sensors"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"14307","DOI":"10.3390\/s121114307","article-title":"Long chain N-acyl homoserine lactone production by Enterobacter sp. isolated from human tongue surfaces","volume":"12","author":"Yin","year":"2012","journal-title":"Sensors"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1751","DOI":"10.1099\/jmm.0.46756-0","article-title":"Conditional production of acyl-homoserine lactone-type quorum-sensing signals in clinical isolates of enterobacteria","volume":"55","author":"Wang","year":"2006","journal-title":"J. Med. Microbiol."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"427","DOI":"10.1016\/j.jep.2005.11.025","article-title":"Anti-quorum sensing activity of medicinal plants in southern Florida","volume":"105","author":"Adonizio","year":"2006","journal-title":"J. Ethnopharmacol."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"2261","DOI":"10.1021\/np100872k","article-title":"Malabaricone C from Myristica cinnamomea exhibits anti-quorum sensing activity","volume":"74","author":"Chong","year":"2011","journal-title":"J. Nat. Prod."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"4016","DOI":"10.3390\/s120404016","article-title":"Inhibition of quorum sensing-controlled virulence factor production in Pseudomonas aeruginosa PAO1 by Ayurveda spice clove (Syzygium Aromaticum) bud extract","volume":"12","author":"Krishnan","year":"2012","journal-title":"Sensors"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"4339","DOI":"10.3390\/s120404339","article-title":"Silencing quorum sensing through extracts of Melicope lunu-ankenda","volume":"12","author":"Tan","year":"2012","journal-title":"Sensors"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"6217","DOI":"10.3390\/s130506217","article-title":"Plant-derived natural products as sources of anti-quorum sensing compounds","volume":"13","author":"Koh","year":"2013","journal-title":"Sensors"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"5117","DOI":"10.3390\/s130405117","article-title":"Caffeine as a potential quorum sensing inhibitor","volume":"13","author":"Norizan","year":"2013","journal-title":"Sensors"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"3975","DOI":"10.3390\/s130303975","article-title":"Piper nigrum, Piper betle and Gnetum gnemon-natural food source with anti-quorum sensing properties","volume":"13","author":"Tan","year":"2013","journal-title":"Sensors"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/13\/11\/15242\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:50:26Z","timestamp":1760219426000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/13\/11\/15242"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2013,11,7]]},"references-count":50,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2013,11]]}},"alternative-id":["s131115242"],"URL":"https:\/\/doi.org\/10.3390\/s131115242","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2013,11,7]]}}}