Expression of outer membrane protein D2 and its gene mutation of coding region in drug resistant Pseudomonas aeruginosa induced by carbopenem antibiotics

Objective To investigate the expression of outer membrane protein D2 (OprD2) and its gene mutation of coding region in drug resistant Pseudomonas aeruginosa (PA) induced by carbopenem antibiotics. Methods The resistant mutant strains were selected from the clinically isolated sensitive strains of PA by passage on Muller-Hinton agar containing different concentrations of meropenem or imipenem. OprD2 was analyzed by gel imaging system after SDS-PAGE. The coding region of OprD2 gene was detected by polymerase chain reaction and sequencing analysis. Results The carbopenems-resistant strains of PA by artificial induction were similar to those clinically isolated strains. The expression of OprD2 in carbopenems-resistant strains was significantly lower than that in the homologous sensitive strains in SDS-PAGE atlas. The nucleotide sequence showed three gene mutations of the OprD2 coding region in carboponems-resistant strains of PA at the same time: at position + 84 (C→T) ;at position + 401 (C→A), Thr134→Asp;at position + 959 (A→G), Lys320→Arg. Conclusion The low expression of OprD2 is due to three or more gene mutations at the same time in the coding region of OprD2 gene in carbopenems-resistant strains of PA. Key words: Pseudomonas aeruginosa; Carbopenems; Outer membrane protein D2; Drug resistance; Mutation; Imipenem; Meropenem