First isolation of bla(VIM-2) in Latin America: report from the SENTRY Antimicrobial Surveillance Program.

Carbapenems, mainly imipenem and meropenem, are potent agents for the treatment of infections due to multiresistant Pseudomonas sp. clinical isolates. However, the prevalence of carbapenem resistance in this genus has been increasing worldwide. High-level resistance to carbapenems ( 32 g/ml) is still uncommon in Pseudomonas spp. but can be due to the presence of Ambler class B -lactamases—metallo-lactamases (MBLs) (1). Three different clinically relevant types of mobile MBLs have been described in the literature: IMP, VIM, and SPM (2, 4; H. Kurokawa, T. Yagi, N. Shibata, K. Shibayama, and Y. Arakawa, Letter, Lancet 354:955, 1999). The VIM family has been reported mostly in European and Asian countries, although a distantly related MBL, VIM-7, has been characterized from the United States (5). We are not aware of VIM-type MBLs being reported from Latin America. In this work, we describe the presence of blaVIM-2-producing Pseudomonas sp. isolates and characterize their genetic context among isolates obtained from Latin American medical centers representing Chile and Venezuela. Four isolates of Pseudomonas spp., one of P. fluorescens (43-14926) from a blood culture isolated in December 2002 in Santiago, Chile, and three of P. aeruginosa (49-4583, 49-4596, and 49-4597) recovered from respiratory tract samples between August and September 2002 from the same hospital in Caracas, Venezuela, were obtained as part of the SENTRY Antimicrobial Surveillance Program. According to results of MIC tests performed as described by the National Committee for Clinical Laboratory Standards, the isolates were resistant to all -lactams, aminoglycosides, quinolones, and other antimicrobial agents tested (Table 1). Only polymyxin B was active against all the isolates. MBL phenotypic tests were positive as judged by the disk approximation method (imipenem, meropenem, ceftazidime, EDTA, and 2-mercaptopropionic acid) and the Etest MBL strips (AB Biodisk, Solna, Sweden) (7). These results were confirmed by spectrophotometric assays measuring imipenem hydrolysis, as previously described (4). Imipenem hydrolysis was inhibited by 88 to 97% for each of the strains by EDTA (20 mM) (Table 2). Amplification with primers for the internal region of blaVIMlike genes and 5 conserved sequence and 3 conserved sequence from class 1 integron and subsequent sequencing were performed as described earlier (3, 5). Primers used for amplification and sequencing of the blaVIM gene were VIM-F (5 AAAGTTATGCCGCACTCACC-3 ) and VIM-R (5 -TGCA ACTTCATGTTATGCCG-3 ). Sequencing results of the PCR amplicons revealed the presence of the blaVIM-2 gene in the first position of a class 1 integron, which has qacE /su1l downstream of the MBL gene. This integron gene arrangement has been previously reported for a P. aeruginosa isolate from a patient in France in 1996 (3). Other cases have been reported from P. aeruginosa in Greece in 2000 and from Serratia marcescens in Korea in 2002 (6, 8). Class 1 integrons carrying blaVIM-type genes are now reported to contain genes encoding aminoglycoside-modifying enzymes, and it is uncertain whether the arrangement of the integron without the additional genes is the progenitor. Despite repeated attempts, plasmid DNA analysis of the isolates did not show any plasmids, and transformation experiments were unsuccessful. Experiments in conjugation between the clinical isolates and Escherichia coli K-12 Rif did not yield any transconjugants. These data imply that the blaVIM-2 found in these isolates is likely to be chromosomally carried. AutoTABLE 1. Antimicrobial susceptibility profiles of the blaVIM-2carrying Pseudomonas sp. isolates