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Effect of iron on expression of efflux pump ( ade ABC) and quorum sensing ( lux I, lux R) genes in clinical isolates of Acinetobacter baumannii
Author(s) -
Modarresi Farzan,
Azizi Omid,
Shakibaie Mohammad Reza,
Motamedifar Mohammad,
Valibeigi Behnaz,
Mansouri Shahla
Publication year - 2015
Publication title -
apmis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0903-4641
DOI - 10.1111/apm.12455
Subject(s) - efflux , quorum sensing , acinetobacter baumannii , microbiology and biotechnology , biology , gene , gene expression , acinetobacter , bacteria , antibiotics , genetics , pseudomonas aeruginosa , virulence
Resistance‐nodulation‐division efflux system ( RND ) ade ABC 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 (ade ABC ) genes and QS (luxI, luxR) system by relative quantitative real‐time polymerase chain reaction (q RT‐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. q RT‐PCR analysis showed that in some isolates, expression of both ade ABC and luxI/R was increased more than fourfold in the presence of low iron (20 μ m ), 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.