DETECTION OF DRUG RESISTANCE GENES RESERVIORES IN TNABARS AND R PLASMIDS AND STUDY OF ADERS AND BAERS REGULATORY SYSTEMS EFFECTS ON ADEABC EFFLUX PUMP AMONG ACINETOBACTER BAUMANNII CLINICAL ISOLATES

Background and Aim:The aim of this study was to detecttion of drug resistance genes reserviores in TnAbaRs and R plasmids and study of AdeRS and BaeRS regulatory systems on AdeABC efflux pump among Acinetobacter baumannii clinical isolates with decreased susceptibility to tigecycline.Methods:By using PCR, more than 20 antibiotics resistance genes were tested in term of chromosomal location on AbaRs or R plasmids and the isolates were AbaR mapped. By using Real time PCR, adeB gene expression was evaluated in isolates with decreased susceptibility to tigecycline and were compared with a sensitive strain. The expression levels of adeRS and baeSR genes and their sequence in isolates with decreased susceptibility to tigecycline was evaluated and compared with a sensitive strains.Results:Genes associated with drug resistance were distributed between AbaR and R plasmid. All the isolates in this study were horboring new variants of AbaR. The adeB, adeS, adeR, baeS and baeR genes were overexpressed, in all isolates with decreased susceptibility to tigecycline in compare with the sensitive strain. Sequencing of adeS, adeR, baeS and baeR genes in isolates with decreased susceptibility in compare to the reference strains revealed that all of them suffered multiple amino acid substitutions.Conclusion:The majority of A. baumannii isolates with decreased susceptibility to tigecycline reserve the resistance gene reservoirs in AbaR and R plasmid. Both AdeRS and BaeSR two components systems in A. baumannii isolates with decreased susceptibility to tigecycline were overexpressed.

کلیدواژه ها:

Acinetobacter baumannii ، Tigecycline ، AbaR ، R plasmid ، AdeABCefflux pumps ، AdeSR two components system ، BaeSR two components system