Mutations of Pseudomonas aeruginosa oprD gene in Imipenem-resistant clinical isolates

Objective To study the mutations of Pseudomonas aeruginosa oprD gene in Imipenem-resistant clinical isolates. Methods Random amplified polymorphic DNA typing(RAPD) was carried out to analyse the homology in 10 Imipenem-resistant clinical isolates. Pseudomonas aeruginosa oprD gene in 10 Imipenem-resistant clinical isolates were amplified by polymerase chain reaction and sequenced. Results Ten Imipenem-resistant clinical isolates were divided into four different clones which can not produce metallo β-lactamase. As compared with sequence X63152, oprD gene of Pseudomonas aeruginosa varied greatly. The aberration rates exceed 50%. There were multiple point mutations within 276～387 bp coding region of 30, 11, 9, 20, 31 strains. Due to the mutations of 308 bp G→C and 344 bp C→A, threonine and diaminocaproic acid were replaced by serine and threonine respectively. The DNA deletion of 393～412 bp in oprD gene contributes to the frame shift mutation in the following nucleotide sequence. The deletion of 264～273 bp in the coding region of oprD gene in 13 and 21 clone strains leads to frame shift mutations forming terminal codon TAA(319～321 bp).Base substitutions and multiple point mutations were obvious in the coding regions of 1 and 22 clone strains. Their aberration rates were 54.03% and 74.89% respectively. Conclusions The mutations of Pseudomonas aeruginosa oprD gene in Imipenem-resistant clinical isolates are various.