Classification of OprD sequence and correlation with antimicrobial activity of carbapenem agents in Pseudomonas aeruginosa clinical isolates collected in Japan

Abstract

A total of 99 clinical isolates of metallo-ß-lactamase-negative Pseudomonas aeruginosa collected in Japan between 1998 and 2001 were studied for their susceptibilities to carbapenem agents and corresponding oprD gene mutations. The OprD sequence of each strain was grouped into two major classes, based on the pattern of alterations. Eighty strains (80.8%) were so-called 'full length type', whose OprD proteins were fully encoded. The remaining 19 strains (19.2%) were so-called 'defective type', which possessed deletions or major alterations that might cause conformational changes in the OprD porin protein. The changes in 'defective type' strains led to 15-, 17-and 23-fold increases in the geometric mean MIC for imipenem, meropenem and biapenem compared with 'full length type' strains, respectively. 'Full length type' strains were further classified into six carbapenem susceptible types with the exception of four carbapenemresistant subtypes with additional amino acid substitutions at D43, G183, R154, G314, G316. However, 'defective type' strains were classified into four types as follows: 10 strains which contained a stop codon within the coding region; six strains which contained IS; one strain with a short deletion near the C-terminal domain; and two strains without a stop codon in the sequenced region. Western blot analysis using OprD antibody showed that binding abilities of OprD proteins against 'full length type' strains were normal, whereas those against 'defective type' strains were lost without exception. These results indicate that OprD structure and antimicrobial activities for carbapenem agents proved to be highly correlated in P. aeruginosa Key words carbapenem resistance, OprD, porin protein, Pseudomonas aeruginosa.Carbapenem antibiotics are recognized as one of the most potent agents with activity against Pseudomonas aeruginosa and remain important for the therapy of serious infections due to these pathogens. Recently, however, the strains with resistance to carbapenems have been increasing among clinical isolates of P. aeruginosa (1).Resistance to carbapenems in P. aeruginosa is often due to the impermeability that arises via the loss of the OprD porin, the overproduction of an active efflux pump system, and the production of carbapenem-hydrolyzing ß-lactamase.Carbapenem-hydrolyzing enzymes are divided into two types based on molecular classification: serine enzymes, which are derivatives of class A or class D enzymes, and metallo-enzymes, which belong to class B enzymes. The production of carbapenem-hydrolyzing enzymes lead to

Emergence of VIM-2 and IMP-15 Carbapenemases and Inactivation of oprD Gene in Carbapenem-Resistant Pseudomonas aeruginosa Clinical Isolates from Lebanon

“…AY553333). Moreover, we found that mutational inactivation of the oprD gene was a major determinant of resistance to imipenem, as previously described (2), and SDS-PAGE confirmed the absence of the protein in isolates whose oprD gene was not detected by PCR, as well as in isolate 37, which had a 15-nucleotide deletion, as previously described (15). We report here the first case of cooccurring bla VIM-2 and oprD porin loss in identical isolates of P. aeruginosa.…”

“…Nine strains harbored the IS element ISPa1328 inserted in OprD nucleotide position 419. This IS element was also described in P. aeruginosa in the United States (14), China (3), and Japan (15). This IS can be present in a different OprD location, as described previously (3).…”

Pseudomonas aeruginosa Outer Membrane Vesicles Modulate Host Immune Responses by Targeting the Toll-Like Receptor 4 Signaling Pathway

“…1A). Previously, porin was shown to be related to imipenem and carbapenem resistance (42,43). It is currently unclear why the vesicles from WT PAO1 caused more cytotoxicity to alveolar epithelial cells than did those from PAO1-⌬lasR (Fig.…”

Adaptive and Mutational Resistance: Role of Porins and Efflux Pumps in Drug Resistance

“…In some cases, antibiotic-resistant strains display a complete loss of one or more porins. For example, a lack of the basic amino-acid-selective outer membrane porin OprD in P. aeruginosa carbapenem-resistant clinical isolates can be due to a point mutation leading to an early termination of translation, a deletion, or the presence of an insertion element within the porin-encoding gene (218,261) or can be due to regulatory mutations (110,187). Point mutations in the promoter region that result in a lower level of transcription are another cause of porin loss.…”