Imipenem and cephem resistant Pseudomonas aeruginosa carrying plasmids coding for class B β-lactamase

Abstract

From October 1988 to January 1992, nine isolates of Pseudomonas aeruginosa carrying transferable plasmids encoding imipenem-hydrolyzing beta-lactamase (pI = c. 9.5) were recovered from nine different patients in a neurosurgical ward of a hospital in Japan. The beta-lactamase activities of the sonicated extracts from the transconjugants were inhibited by EDTA and this was partially reversible by the addition of zinc cation. The substrate specificity and pI of the beta-lactamase were similar to those of the metallo beta-lactamases from P. aeruginosa and Serratia marcescens TN9106. All strains were resistant to imipenem, carbenicillin and antipseudomonal cephems including ceftazidime, cefsulodin, cefpirome, while four and five strains were susceptible to piperacillin and aztreonam, respectively. Both low level imipenem resistance and high level cephem resistance were co-transferred with the production of metallo beta-lactamase, while resistance to piperacillin, aztreonam, and high level imipenem-resistance were not selected. Production of chromosomal cephalosporinase in piperacillin resistant strains was derepressed, and production of outer membrane protein of D2 was diminished in highly imipenem resistant strains. Six strains were isolated in 1991, and the amounts of antipseudomonal agents, especially imipenem, used in the neurosurgical ward increased markedly in this year. Only three of the nine isolates had the same serotype, pyocin type and phage type. Our results suggest that the repeated isolation of imipenem and cephem-resistant P. aeruginosa producing metallo beta-lactamase was related to the high usage of antipseudomonal beta-lactam antibiotics such as imipenem, and was exacerbated by the dissemination of a plasmid.

PCR Typing of Genetic Determinants for Metallo-β-Lactamases and Integrases Carried by Gram-Negative Bacteria Isolated in Japan, with Focus on the Class 3 Integron

“…Since 1988, transferable carbapenem resistance has been found in several P. aeruginosa strains isolated in Toyama Prefecture, Japan (12,25). In 1991, an IMP-1 type MBL, initially characterized in a strain of S. marcescens, gave high-level resistance to various broad-spectrum ␤-lactams including imipenem (6,14).…”

Presence of Pseudomonas putida Strains Harboring Plasmids Bearing the Metallo-β-Lactamase Gene bla IMP in a Hospital in Japan

“…Laboratory P. aeruginosa strains, rifampin-resistant ML5017 (Ile Ϫ , Val Ϫ , Lys Ϫ , Met Ϫ ) and rifampin-susceptible PAO4141 (Pro Ϫ , Met Ϫ ), were used for the recipients of plasmids in conjugation or transformation (11,18).…”

“…Plasmids with identical DNA and drug resistance patterns were found in P. putida strains with identical PFGE patterns and with different PFGE patterns. We presumed that P. putida was one of the resident species in inpatients and especially in hospital environments, spreading drug resistance genes via plasmids among P. putida strains and supplying them to more pathogenically important species, such as P. aeruginosa.Carbapenem-hydrolyzing metallo-␤-lactamases, especially IMP-type and VIM-type metallo-␤-lactamases, are clinically important, because these enzymes effectively hydrolyze almost all ␤-lactam antibiotics except monobactams, conferring resistance to penicillins and cephems in addition to carbapenems on pathogenic bacteria (12,13,18,21,23,32). Since genes encoding these metallo-␤-lactamases (bla IMP and bla VIM ) and their variant genes have become easy to detect using the PCR method, dissemination of these genes in clinical isolates has been widely observed in gram-negative bacteria, especially in Pseudomonas aeruginosa and other non-glucose-fermenting bacteria (3, 4, 6, 8-10, 26-30, 34, 35).…”

“…A total of 32 imipenem (IPM)-resistant P. putida strains isolated from 1997 to 2001 in Gunma University Hospital were investigated. The isolates consisted of 27 strains from different inpatients and 5 strains from the ward environments.Laboratory P. aeruginosa strains, rifampin-resistant ML5017 (Ile Ϫ , Val Ϫ , Lys Ϫ , Met Ϫ ) and rifampin-susceptible PAO4141 (Pro Ϫ , Met Ϫ ), were used for the recipients of plasmids in conjugation or transformation (11,18).Media. Sensitivity test broth and sensitivity disk agar (Nissui Pharmaceutical Co., Tokyo, Japan) were used routinely.…”

“…Carbapenem-hydrolyzing metallo-␤-lactamases, especially IMP-type and VIM-type metallo-␤-lactamases, are clinically important, because these enzymes effectively hydrolyze almost all ␤-lactam antibiotics except monobactams, conferring resistance to penicillins and cephems in addition to carbapenems on pathogenic bacteria (12,13,18,21,23,32). Since genes encoding these metallo-␤-lactamases (bla IMP and bla VIM ) and their variant genes have become easy to detect using the PCR method, dissemination of these genes in clinical isolates has been widely observed in gram-negative bacteria, especially in Pseudomonas aeruginosa and other non-glucose-fermenting bacteria (3, 4, 6, 8-10, 26-30, 34, 35).…”