Multidrug-resistant epidemic clones among bloodstream isolates of Pseudomonas aeruginosa in the Czech Republic.

To determine whether the high proportion of antimicrobial resistance among hospital isolates of Pseudomonas aeruginosa in the Czech Republic is associated with the spread of multidrug-resistant clones, we investigated 108 bloodstream isolates collected prospectively in 2007. The isolates originated from 48 hospitals in 36 cities and were serotyped, tested for susceptibility to 10 anti-Pseudomonas agents and studied by multilocus sequence typing, macrorestriction analysis and class 1 integron typing. Forty-five isolates were fully susceptible, while 14 and 49 isolates were resistant to 1-2 and 3-9 agents, respectively. A total of 42 multilocus sequence types (ST) were identified, of which ST235 (serotype O11), ST175 (O4) and ST132 (O6) included 19, 16 and 5 isolates, respectively. These three STs encompassed 40 (82%) of 49 isolates resistant to more than two agents and originated from 29 hospitals in 22 cities. Isolates of the same ST had highly similar macrorestriction patterns. Twelve ST235 isolates harbored an integron variable region with the gene cassette array of aacA7-aadA6-orfD, while 15 ST175 isolates shared a region with the aadB-aadA13 array and all ST132 isolates carried a region with aacA4. A carbapenemase-encoding gene (bla(IMP-7)) was detected in a single strain (ST357). In conclusion, the multidrug resistance of Czech P. aeruginosa bloodstream isolates in 2007 was predominantly associated with three epidemic clones, one of which belongs to international clonal complex CC235.