Effect of iron on expression of efflux pump (adeABC) and quorum sensing (luxI, luxR) genes in clinical isolates of Acinetobacter baumannii.
Resistance-nodulation-division efflux system (RND) adeABC contributes to intrinsic resistance to various drug classes in Acinetobacter baumannii. Similarly, quorum sensing (QS) plays an important role in the biofilm formation and pathogenicity of this bacterium. The aims of this study were to evaluate the influence of iron limitation on the expression of efflux pump (adeABC) genes and QS (luxI, luxR) system by relative quantitative real-time polymerase chain reaction (qRT-PCR). In addition, DNA sequence and phylogenetic relatedness of biofilm-associated protein (Bap) gene was also investigated. Sixty-five multidrug-resistant isolates of A. baumannii were recovered from ICU patients of three hospitals in Kerman, Iran. The isolates were highly resistant to at least 11 antibiotics (MIC ≥64 μg/mL); however, 87% and 89% were susceptible to colistin and tigecycline, respectively (MIC 0.05 μg/mL) (p ≤ 0.05). We detected the presence of RND efflux pump, QS, and bap genes with the frequencies of 92% (adeA), 61.5% (adeB), 84.6% (adeC), 80% (luxI), 61% (luxR), and 66% (bap), respectively. qRT-PCR analysis showed that in some isolates, expression of both adeABC and luxI/R was increased more than fourfold in the presence of low iron (20 μm), suggesting the additional regulatory role of iron on both efflux pump and QS system. Alignment and phylogenetic analysis on the strong biofilm forming isolates confirmed that the fragments amplified were indeed part of bap gene and deduced sequence was similar to A. baumannii K9B410.
Department of Microbiology and Virology, Afzalipour School of Medicine, Kerman, Iran.
Farzan
F
Modarresi
Department of Microbiology and Virology, Afzalipour School of Medicine, Kerman, Iran.
Omid
O
Azizi
Department of Microbiology and Virology, Afzalipour School of Medicine, Kerman, Iran.|Research Center for Infectious Diseases and Tropical Medicine, Kerman, Iran.|Environmental Health Engineering Research Center, Kerman University of Medical Sciences, Kerman, Iran.
Mohammad Reza
MR
Shakibaie
Shiraz HIV/AIDS Research Center, Shiraz, Iran.|Departments of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Mohammad
M
Motamedifar
Department of Pathology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Behnaz
B
Valibeigi
Department of Microbiology and Virology, Afzalipour School of Medicine, Kerman, Iran.
Shahla
S
Mansouri
D000151:Acinetobacter Infections / Q000188:drug therapy / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D000368:Aged; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics; D008875:Middle Aged; D008969:Molecular Sequence Data; D010802:Phylogeny; D053038:Quorum Sensing / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
C492436:AdeA protein, Acinetobacter baumannii; C445684:AdeB protein, Acinetobacter baumannii; C492437:AdeC protein, Acinetobacter baumannii; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C085427:LuxI protein, Bacteria; D026901:Membrane Transport Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C064778:LuxR autoinducer binding proteins; D007501:Iron
Acinetobacter baumannii; RND efflux pump; biofilm; quorum sensing genes; relative quantitative real-time PCR