VIM metallo--lactamase-producing serotype O11 or O12 Pseudomonas aeruginosa isolates infecting or colonizing 19 patients from seven hospitals in Hungary were characterized between October 2003 and November 2005. Macrorestriction analysis revealed the involvement of hospitals from three different towns in northwest Hungary in an outbreak caused by VIM-4-producing P. aeruginosa.The worldwide spread of acquired metallo--lactamase (MBL)-producing gram-negative pathogens was observed in the past decade, with the bla VIM -type acquired MBL genes currently being the most prevalent in Europe (16,23). The first VIM-producing Pseudomonas aeruginosa clinical isolates in Hungary (isolates PA396 and PA450) were characterized at the National Center for Epidemiology in 2003 (7). We established routine screening of carbapenem-resistant Pseudomonas sp. isolates provided by collaborating regional laboratories for acquired MBL genes. In 2005, MBL-positive isolates from six towns in Hungary were detected (Fig. 1). Our aim was to characterize these isolates and to examine the clonal relationships between them and between the major European multiresistant serotype O12 P. aeruginosa clone, clone P12 (4, 8, 10).The VIM-positive clinical and environmental isolates tested in this study are listed in Table 1, together with the previously published control isolates PA396 and PA450 (7). Isolates P12-Q and P12-E were from French patients "Q" and "E," respectively, who participated in a previous clone P12-related study (8). MICs were determined by the agar dilution method (1) for -lactam antibiotics and by the Etest (AB Biodisk, Solna, Sweden) for other antibiotics. The MBL Etest and the imipenem-EDTA, ceftazidime-EDTA, and cefepime-EDTA double-disk methods were used for phenotypic screening (21,22).bla VIM genes and class 1 integrons were detected by PCR (7). The variable regions of the integrons from isolates PA555 and MB197 were sequenced by using the following primers, together with those described previously (7): primer 197F (5Ј-AAT
CGC TCA GTC GCC GAG-3Ј), primer 197R1 (5Ј-TAG TGC TTC TCC GTC GGG-3Ј), primer 197R2 (5Ј-AAT TCC GCA TTG CTG ATC G-3Ј), and primer 197R3 (5Ј-AGG TAT TGC TCC TGC ACT T-3Ј). Isolate PA555 was selected for full integron sequencing in 2003, as it was the first VIM-positive isolate from Pécs, Hungary, while isolate MB197 was selected as an invasive isolate from a cluster of clonally closely related VIMpositive isolates from northwest Hungary. For the other VIMproducing isolates, the integron structures were determined by PCR mapping and partial sequencing.Pulsed-field gel electrophoresis (PFGE) was performed as described earlier (11), with modifications, and the patterns were interpreted by using Fingerprinting II Informatix software (Bio-Rad, Madrid, Spain). Pseudomonas aeruginosa antisera (Bio-Rad, Marnes-la-Coquette, France) were used for serotyping.Conjugation experiments were carried out with strains Escherichia coli J5-3 Rif r and P. aeruginosa PAO4089Rp (6, 7) as the recipients. Transconjugants were selec...