Physiological studies of the regulation of beta-lactamase expression in Pseudomonas maltophilia

Rosta, S; Mett, Helmut

doi:10.1128/jb.171.1.483-487.1989

Cited by 6 publications

(7 citation statements)

References 22 publications

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“…Rosta and Mett found that total induced ␤-lactamase activity in S. maltophilia decreases at a rate of 50% per generation after the maximal peak (15). In the present study, a difference between the induction of L1 and that of L2 was apparent.…”

supporting

confidence: 44%

“…The induced ␤-lactamase activity has been shown to be linearly correlated to the inducer concentration for Pseudomonas aeruginosa and S. maltophilia (13,15). In the present study, a roughly linear correlation was observed with KJ⌬L2 but not with KJ⌬L1.…”

supporting

confidence: 41%

“…In the present study, a roughly linear correlation was observed with KJ⌬L2 but not with KJ⌬L1. This lower dependence of the induction of L1 on the inducer concentration is a phenomenon that has not yet been reported in ␤-lactamase induction of gram-negative bacteria (13,15). Figure 3 shows the induction of the L1 and L2 genes by various ␤-lactams.…”

mentioning

confidence: 67%

“…Its ␤-lactamase extract was prepared from the periplasmic contents (9) using ampicillin (100 g/ml) as an inducer and subjected to an isoelectric focusing (IEF) assay (10). Two ␤-lactamases were revealed by IEF, of pIs 6.0 and 8.2, which can be assigned as the pIs of L1 and L2, respectively (5,15).…”

mentioning

confidence: 99%

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Induction of L1 and L2 β-Lactamases of Stenotrophomonas maltophilia

Huang

et al. 2008

Antimicrob Agents Chemother

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confidence: 44%

supporting

confidence: 41%

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confidence: 67%

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confidence: 99%

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Induction of L1 and L2 β-Lactamases of Stenotrophomonas maltophilia

Huang

et al. 2008

Antimicrob Agents Chemother

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“…Resistance to these agents is by a combination of intrinsic and acquired determinants. Resistance to ␤-lactams is primarily intrinsic, mediated by two inducible ␤-lactamases, L1 and L2 (10,18,(21)(22)(23). L1 is a Zn 2ϩ -dependent metalloenzyme that hydrolyzes virtually all classes of ␤-lactams, including penicillins, cephalosporins, and carbapenems but excluding monobactams (9,18,22,30), while L2 is a serine active-site cephalosporinase (23, 31).…”

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confidence: 99%

Plasmid Location and Molecular Heterogeneity of the L1 and L2 β-Lactamase Genes of Stenotrophomonas maltophilia

Avison

Higgins

Heldreich

et al. 2001

Antimicrob Agents Chemother

121

105

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An approximately 200-kb plasmid has been purified from clinical isolates of Stenotrophomonas maltophilia. This plasmid was found in all of the 10 isolates examined and contains both the L1 and the L2 ␤-lactamase genes. The location of L1 and L2 on a plasmid makes it more likely that they could spread to other gram-negative bacteria, potentially causing clinical problems. Sequence analysis of the 10 L1 genes revealed three novel genes, L1c, L1d, and L1e, with 8, 12, and 20% divergence from the published strain IID 1275 L1 (L1a), respectively. The most unusual L1 enzyme (L1e) displayed markedly different kinetic properties, with respect to hydrolysis of nitrocefin and imipenem, compared to those of L1a (250-and 100-fold lower k cat /K m ratios respectively). L1c and L1d, in contrast, displayed levels of hydrolysis very similar to that of L1a. Several nonconservative amino acid differences with respect to L1a, L1b, L1c, and L1d were observed in the substrate binding-catalytic regions of L1e, and this could explain the kinetic differences. Three novel L2 genes (L2b, L2c, and L2d) were sequenced from the same isolates, and their sequences diverge from the published sequence of strain IID 1275 L2 (L2a) by 4, 9, and 25%, respectively. Differences in L1 and L2 gene sequences were not accompanied by similar divergences in 16S rRNA gene sequences, for which differences of <1% were found. It is therefore apparent that the L1 and L2 genes have evolved relatively quickly, perhaps because of their presence on a plasmid.In recent years there have been major increases in the frequencies with which certain, previously rare bacterial species have been identified as the causes of hospital-acquired bacteremias (26). Three principle factors have combined to bring about this change: (i) increased numbers of hospitalized patients who are severely immunosuppressed; (ii) an increase in complicated surgical procedures, such as transplant and oncology surgery, and the use of intravenous catheters; and (iii) the prophylactic use of antibiotics, particularly ␤-lactams (26). A prime example of such an emergent pathogen is Stenotrophomonas maltophilia (6,11,25,26,28). Its tolerance to silverlined catheters (28) and its inherent resistance to many antibacterial drugs, including most, if not all, ␤-lactams (1, 26, 27), give it a survival advantage over other potential pathogens in the hospital environment. Its incidence as a cause of nosocomial bacteremias caused by gram-negative organisms is now second only to that of bacteremia caused by Pseudomonas aeruginosa, and the frequency of its isolation is increasing (25). It is also a significant cause of bacterial infection among young adults with cystic fibrosis (10).The mechanisms of antibacterial drug resistance in S. maltophilia have not been studied in detail, but it is expected that many of the acquired mechanisms found in P. aeruginosa and other gram-negative bacteria are likely to be present. Strains that are resistant to all known aminoglycosides, quinolones, ␤-lactams, chloramphenicol, ri...

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