title: Biofilm Formation Caused by Clinical Acinetobacter baumannii Isolates Is Associated with Overexpression of the AdeFGH Efflux Pump.
abstract: Chronic wound infections are associated with biofilm formation, which in turn has been correlated with drug resistance. However, the mechanism by which bacteria form biofilms in clinical environments is not clearly understood. This study was designed to investigate the biofilm formation potency of Acinetobacter baumannii and the potential association of biofilm formation with genes encoding efflux pumps, quorum-sensing regulators, and outer membrane proteins. A total of 48 clinically isolated A. baumannii strains, identified by enterobacterial repetitive intergenic consensus (ERIC)-PCR as types A-II, A-III, and A-IV, were analyzed. Three representative strains, which were designated A. baumannii ABR2, ABR11, and ABS17, were used to evaluate antimicrobial susceptibility, biofilm inducibility, and gene transcription (abaI, adeB, adeG, adeJ, carO, and ompA). A significant increase in the MICs of different classes of antibiotics was observed in the biofilm cells. The formation of a biofilm was significantly induced in all the representative strains exposed to levofloxacin. The levels of gene transcription varied between bacterial genotypes, antibiotics, and antibiotic concentrations. The upregulation of adeG correlated with biofilm induction. The consistent upregulation of adeG and abaI was detected in A-III-type A. baumannii in response to levofloxacin and meropenem (1/8 to 1/2× the MIC), conditions which resulted in the greatest extent of biofilm induction. This study demonstrates a potential role of the AdeFGH efflux pump in the synthesis and transport of autoinducer molecules during biofilm formation, suggesting a link between low-dose antimicrobial therapy and a high risk of biofilm infections caused by A. baumannii. This study provides useful information for the development of antibiofilm strategies.
authors.affiliation: The Third People's Hospital of Wuxi, Wuxi, Jiangsu Province, People's Republic of China.
authors.forename: Xinlong
authors.initials: X
authors.lastname: He
authors.affiliation: Jiangsu Institute of Parasitic Diseases, Key Laboratory of Parasitic Disease Control and Prevention (Ministry of Health), Jiangsu Provincial Key Laboratory of Parasite Molecular Biology, Wuxi, Jiangsu Province, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Lu
authors.affiliation: The Third People's Hospital of Wuxi, Wuxi, Jiangsu Province, People's Republic of China.
authors.forename: Fenglai
authors.initials: F
authors.lastname: Yuan
authors.affiliation: The Third People's Hospital of Wuxi, Wuxi, Jiangsu Province, People's Republic of China.
authors.forename: Donglin
authors.initials: D
authors.lastname: Jiang
authors.affiliation: The Third People's Hospital of Wuxi, Wuxi, Jiangsu Province, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhao
authors.affiliation: The Third People's Hospital of Wuxi, Wuxi, Jiangsu Province, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhu
authors.affiliation: The Third People's Hospital of Wuxi, Wuxi, Jiangsu Province, People's Republic of China.
authors.forename: Huali
authors.initials: H
authors.lastname: Cheng
authors.affiliation: Jiangsu Institute of Parasitic Diseases, Key Laboratory of Parasitic Disease Control and Prevention (Ministry of Health), Jiangsu Provincial Key Laboratory of Parasite Molecular Biology, Wuxi, Jiangsu Province, People's Republic of China Public Health Research Center, Jiangnan University, Wuxi, Jiangsu Province, People's Republic of China caojuncn@hotmail.com luguozhongms@163.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Cao
authors.affiliation: The Third People's Hospital of Wuxi, Wuxi, Jiangsu Province, People's Republic of China caojuncn@hotmail.com luguozhongms@163.com.
authors.forename: Guozhong
authors.initials: G
authors.lastname: Lu
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics*; D008826:Microbial Sensitivity Tests / Q000379:methods; D053038:Quorum Sensing / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins