Metallo-β-Lactamases in Clinical Pseudomonas Isolates in Taiwan and Identification of VIM-3, a Novel Variant of the VIM-2 Enzyme

Abstract

A total of 209 clinical isolates of Pseudomonas (193 Pseudomonas aeruginosa, 10 P. putida, 4 P. stutzeri, and 2 P. fluorescens isolates) with reduced susceptibilities to imipenem and/or ceftazidime were subjected to PCR assays with primers specific for bla IMP-1 , bla IMP-2 , bla VIM-1 , and bla VIM-2 and sequence analysis to identify the metallo-␤-lactamases (MBLs) prevalent among these organisms in Taiwan; and 21 isolates gave positive results. Five isolates including two P. putida and three P. stutzeri isolates were found to carry bla IMP-1 , and six isolates including five P. putida and one P. stutzeri isolates harbored bla VIM-2 . The remaining 10 isolates were P. aeruginosa, and all were found to carry a novel variant of bla VIM-2 , designated bla VIM-3 . There are only two nucleotide differences between bla VIM-2 and bla VIM-3 , leading to two amino acid alterations. Our findings indicate that VIM-2 and its variant have become the most prevalent metalloenzymes in Pseudomonas in Taiwan. Southern hybridization with the bla VIM-2 -, bla VIM-3 -, and bla IMP-1 -specific probes revealed that only two VIM-2-producing P. putida isolates appeared to carry the MBL gene on plasmids. Pulsed-field gel electrophoresis showed that six VIM-3-producing P. aeruginosa isolates and two IMP-1-producing P. stutzeri isolates were genetically related, suggesting that the spread of these MBL genes in Taiwan could be due to clonal dissemination as well as genetic exchange between different clones.Carbapenems are often used as antibiotics of last resort for the treatment of infections caused by gram-negative bacteria resistant to other ␤-lactam agents because of their broad spectra of activity and stability to hydrolysis by most ␤-lactamases including extended-spectrum ␤-lactamases (4,12,26,27). The mechanisms of resistance to carbapenems in Pseudomonas aeruginosa often result from reduced levels of drug accumulation or increased levels of expression of pump efflux (8,15,17). The resistance is occasionally due to production of metallo-␤-lactamases (MBLs), which can be either chromosomally encoded or plasmid mediated (8,13,22,28,32). IMP-1 was the first MBL identified in P. aeruginosa (28,29). The enzyme has also been described in other nonfastidious, gram-negative nonfermenters and members of the family Enterobacteriaceae (9,10,20,29). Several novel MBLs were identified recently, including VIM-1 from P. aeruginosa and IMP-2 from Acinetobacter baumannii in Italy (13, 25), VIM-2 from P. aeruginosa in France (22), and IMP-3 from Shigella flexneri in Japan (11). The spread of MBLs in gram-negative rods has been described in several other countries and is becoming an emerging threat , abstr. 2003, p. 123, 2000). It remains unknown whether these MBLs have appeared in Taiwan. Thus, the purpose of the present study was to determine the IMP-and VIM-type MBLs prevalent among clinical isolates of the genus Pseudomonas in Taiwan. MATERIALS AND METHODSBacterial strains. The isolates studied were selected from clinical isolates of Pseudomonas ...

Prevalence of Metallo-beta-Lactamase producing Pseudomonas aeruginosa in wound infections in Duhok city, Iraq

“…9 Our investigation accords with other studies. 10,11,12 Our data deviates from reports of two studies by El-Kholy et al 13 and Pitout et al 14 issued higher rates of MBLs among P. aeruginosa that were (62%) and (46%) respectively. MBLs among P. aeruginosa have been increasingly recognized from clinical isolates worldwide; for example (55.2%) in Egypt and (66.7%) in Saudi Arabia, 15 in Brazil (76.7%), 16 in France (46%), 17 in India (13.6%), 18 in Iran (20%), 19 and in Korea(24.2%).…”

Detection Rate of Metallo-β-Lactamase-Expressing Genes; blaVIM-1, blaVIM-2 and blaSPM-1 in Pseudomonas aeruginosa Isolates

“…22 Previous studies demonstrated that IMP and VIM producer genes of MBLs were also common in Asian studies. [23][24][25] VIM type was also highly prevalent in Turkey. 26 In previous studies in Egypt and Taiwan, VIM-2 demonstrated the highest outbreak among imipenem-resistant P. aeruginosa strains.…”

IMP-1 and a Novel Metallo-β-Lactamase, VIM-6, in Fluorescent Pseudomonads Isolated in Singapore

“…VIMtype enzymes have since been found in Greece (11) and in Turkey and Portugal (2), including the new variants VIM-4 and VIM-5 (GenBank accession number AY144612). The other focus for VIM-type enzymes appears to be the Far East, notably, VIM-2 in Korea (6) and VIM-3 in Taiwan (15). VIM-2, VIM-3, and VIM-6 appear to form a cluster (with at least 99.2% amino acid identity within the cluster) whose amino acid sequences differ from those of the other VIM enzymes by about 10% (Fig.…”

“…DNA probes were synthesized by using the PCR DIG Probe Synthesis kit (Roche Diagnostics GmbH, Mannheim, Germany) and primers specific for bla IMP-1 and bla VIM-2 , as described by Yan et al (15). DNA extracts from P. putida DB33824/00 and DU25151/00 served as templates.…”