Plasmid-mediated dissemination of the metallo-beta-lactamase gene blaIMP among clinically isolated strains of Serratia marcescens

Abstract

The distribution of strains producing metallo-␤-lactamase among 105 strains of Serratia marcescens was investigated. All of these strains were isolated in seven general hospitals located in Aichi Prefecture, Japan, from April to May 1993. Southern hybridization analysis suggested that four S. marcescens strains, AK9373, AK9374, AK9385, and AK9391, had a metallo-␤-lactamase genes similar to the bla IMP gene found by our laboratory (E. Osano, Y. Arakawa, R. Wacharotayankun, M. Ohta, T. Horii, H. Ito, F. Yoshimura, and N. Kato, Antimicrob. Agents Chemother. 38:71-78, 1994), and these four strains showed resistance to carbapenems as well as to the other broad-spectrum ␤-lactams. In particular, strains AK9373, AK9374, and AK9391 showed an extraordinarily high-level resistance to imipenem (MICs, м64 g/ml), whereas strain AK9385 demonstrated moderate imipenem resistance (MIC, 8 g/ml). The imipenem resistance of AK9373 was transferred to Escherichia coli CSH2 by conjugation with a frequency of 10 ؊5. The DNA probe of the bla IMP gene hybridized to a large plasmid (approximately 120 kb) transferred into the E. coli transconjugant as well as to the large plasmids harbored by AK9373. On the other hand, although we failed in the conjugational transfer of imipenem resistance from strains AK9374, AK9385, and AK9391 to E. coli CSH2, imipenem resistance was transferred from these strains to E. coli HB101 by transformation. A plasmid (approximately 25 kb) was observed in each transformant which acquired imipenem resistance. The amino acid sequence at the N terminus of the enzyme purified from strain AK9373 was identical to that of the metallo-␤-lactamase IMP-1. In contrast, strains ES9348, AK9386, and AK93101, which were moderately resistant to imipenem (MICs, м4 to Ϲ8 g/ml), had no detectable bla IMP gene. As a conclusion, 19% of clinically isolated S. marcescens strains in Aichi Prefecture, Japan, in 1993 were resistant to imipenem (MICs, Ն2 g/ml), and strains which showed high-level imipenem resistance because of acquisition of a plasmid-mediated bla IMP -like metallo-␤-lactamase gene had already proliferated as nosocomial infections, at least in a general hospital.

Phenotypic and Genetic Characterization of Carbapenemase and ESBLs Producing Gram-negative Bacteria (GNB) Isolated from Patients with Cystic Fibrosis in Tehran Tospitals

“…IMP-1 was the first identified acquired MBL [16] and has spread among Enterobacteriaceae, Pseudomonas aeruginosa, and other nonfastidious Gram-negative nonfermenters in Japan [17][18][19][20].…”

Characteristics and management of Enterobacteriaceae harboring IMP-4 or IMP-8 carbapenemase in a tertiary hospital

“…IMP-type metalloenzymes have been reported worldwide, with a higher prevalence in southern Europe and Asia. The first acquired MBL, IMP-1, was reported in Serratia marcescens in Japan in 1991 34 . Since then, IMP-type enzymes has been described worldwide, and endemicity of IMP-type enzymes has been reported in in many countries 35 .…”

Case Report of Enterobacter cloacae Producing IMP-8 Carbapenemase Isolated from Secretions of Burn Patients and Diabetes Patients with Diabetic Foot

“…IMP of class B MBL is one of the early described carbapenemases in Enterobacteriaceae. Since the first report of IMP-1 in Serratia marcescens from Japan in 1991 (2), IMP carbapenemase have been described worldwide, particularly in Asian countries, such as Japan, Indian, and Korea (1,3). In China, the gene types found in E. cloacae are IMP-1, IMP-4, IMP-8 and IMP-26, and carbapenem resistance in E. cloacae is becoming a great concern in the region (4,5).…”