Characteristics of rare ST463 carbapenem-resistant Pseudomonas aeruginosa clinical isolates from blood.

OBJECTIVES

This study aimed to elucidate resistance to carbapenems and fluoroquinolones, the transmission mechanism of bla, and the virulence characteristics of a Pseudomonas aeruginosa strain (TL3773) isolated in East China.

METHODS

The virulence and resistance mechanisms of TL3773 were investigated by whole genome sequencing (WGS), comparative genomic analysis, conjugation experiments, and virulence assays.

RESULTS

This study isolated carbapenem-resistant P. aeruginosa from blood resistant to carbapenems. The patient's clinical data showed poor prognosis compounded by multiple sites of infection. WGS showed that TL3773 carried aph (3')-IIb, bla, bla, fosA, catB7, and two crpP resistance genes on chromosome, and the carbapenem resistance gene bla on plasmid. We identified a novel crpP gene named TL3773-crpP2. Cloning experiments proved that TL3773-crpP2 was not the primary cause of fluoroquinolone resistance in TL3773. GyrA and ParC mutations may confer fluoroquinolone resistance. The bla genetic environment was IS26-TnpR-ISKpn27-bla-ISKpn6-IS26-Tn3-IS26, potentially mediating the transmission of bla in P. aeruginosa. The overall virulence of TL3773 was lower than that of PAO1. However, the pyocyanin and biofilm formation of TL3773 was higher than that of PAO1. WGS further indicated that TL3773 was less virulent than PAO1. Phylogenetic analysis showed that TL3773 was most similar to the P. aeruginosa isolate ZYPA29 from Hangzhou, China. These observations further indicate that ST463 P. aeruginosa is rapidly spreading.

CONCLUSIONS

The threat of ST463 P. aeruginosa harbouring bla is emergent and may pose a threat to human health. More extensive surveillance and effective actions are urgently needed to control its further spread.