Dissemination of transposon Tn6001 in carbapenem-non-susceptible and extensively drug-resistant Pseudomonas aeruginosa in Taiwan.
OBJECTIVE
To investigate the prevalence of metallo-beta-lactamases (MBLs) and Tn6001 in carbapenem-non-susceptible Pseudomonas aeruginosa (CNSPA). The CNSPA included extensively drug-resistant P. aeruginosa (XDRPA) and non-XDRPA isolates in Taiwan.


METHODS
A total of 308 CNSPA isolates collected at a medical centre from 2000 to 2005 and 26 XDRPA collected from six medical centres in different regions of Taiwan in 2003 were included. MBL genes and Tn6001 were detected by PCR. Clonal relatedness was determined by PFGE.


RESULTS
Of the 308 CNSPA isolates, 30 (10%) were XDRPA, including 27 (9%) colistin-only-susceptible (COS) and 3 (1%) colistin-only-intermediate (COI) P. aeruginosa. bla(VIM-3) was found in 16 (53%) isolates of the XDRPA (n = 30), whereas only 72 (26%) of the non-XDRPA (n = 278) carried the gene. In450 was higher in COS P. aeruginosa (12/27; 44%) than in non-XDRPA isolates (53/278; 19%). Tn6001 was highest in COS P. aeruginosa (11/27; 41%), followed by COI P. aeruginosa (1/3; 33%), and lowest in non-XDRPA (46/278; 17%). Of 26 XDRPA from six medical centres, higher prevalences of bla(VIM-3) (16/26; 62%), In450 (16/26; 62%) and Tn6001 (12/26; 46%) were found. Genotyping by PFGE revealed 60 pulsotypes. Hybridization of a bla(VIM-3)-specific probe following PFGE suggested that the mobile element Tn6001 might have transferred horizontally.


CONCLUSIONS
Tn6001 and In450 play an important role in the dissemination of CNSPA and XDRPA. The prevalence of these genetic constituents was higher in XDRPA than in non-XDRPA isolates, suggesting that the mobile element Tn6001 might have transferred horizontally.
Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan.
Sung-Pin
SP
Tseng
Jui-Chang
JC
Tsai
Lee-Jene
LJ
Teng
Po-Ren
PR
Hsueh
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D015780:Carbapenems / Q000494:pharmacology*; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D023061:Gene Order; D022761:Gene Transfer, Horizontal; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D016133:Polymerase Chain Reaction / Q000379:methods; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D026801:Synteny; D013624:Taiwan; D018440:beta-Lactam Resistance
D000900:Anti-Bacterial Agents; D015780:Carbapenems; D004251:DNA Transposable Elements; D004269:DNA, Bacterial