| Objective and Purpose: Pseudomonas aeruginosais an important opportunistic human pathogen implicated in respiratory infections.Carbapenems are a class of ?-lactam antibiotics that are highly effective for treating infections caused by MDR P.aeruginosa.Previous studies have shown that the decreased expression of outer membrane protein Opr D,opr D mutations,loss of Opr D,and overproduction of metallo ?-lactamases and Amp C mainly contribute to carbapenem resistance.Method and Result: In this study,the prevalence and characteristics of 160 clinical isolates of P.aeruginosa collected from a hospital in China were investigated.Multilocus sequence typing(MLST)was used to characterize the genetic backgrounds of these clinical isolates.Multilocus sequence typing analysis demonstrated that these isolates were highly diverse;68 sequence types(STs)were identified,of which 28 were novel sts.Polygenic and e BURST analysis demonstrated genetically similar clones with dissimilar resistance profiles.opr D polymorphism,particularly those resulting in L7 and L8 shortening,are the major causes of carbapenem sensitivity.Moreover,our results also show a high incidence of carbapenem resistant strains with a large deletion of Opr D or premature stop coden,indicating that intact Opr D is necessary for susceptibility to carbapenem.Conclusion: MLST revealed the genetic diversity of clinical P.aeruginosa and the divergence of transmission.The sequence analysis of opr D gene showed that the deletion of Opr D protein could not fully explain the current mechanism of carbapenem resistance,and it needs to be combined with other mechanisms to further confirm.In addition,our analysis of clinical opr D gene sequence diversity in P.aeruginosa can be used as a complement to the laboratory's reference strains.These findings will help us to understand the mechanism of carbapenem resistant P.aeruginosa isolates better. |
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