Genetic and Biochemical Characterization of a Novel Metallo- -Lactamase, TMB-1, from an Achromobacter xylosoxidans Strain Isolated in Tripoli, Libya

Cardiff University, Cardiff, United Kingdom.
Antimicrobial Agents and Chemotherapy (Impact Factor: 4.48). 01/2012; 56(5):2241-5. DOI: 10.1128/AAC.05640-11
Source: PubMed


An Achromobacter xylosoxidans strain from the Tripoli central hospital produced a unique metallo-β-lactamase, designated TMB-1, which is related to DIM-1
(62%) and GIM-1 (51%). blaTMB-1 was embedded in a class 1 integron and located on the chromosome. The TMB-1 β-lactamase has lower kcat values than both DIM-1 and GIM-1 with cephalosporins and carbapenems. The Km values were more similar to those of GIM-1 than those of DIM-1, with the overall kcat/Km values being lower than those for GIM-1 and DIM-1.


Available from: Mark A Toleman
  • Source
    • "The Achromobacter strain exhibited the property of the intrinsic multidrug resistance that was a crucial challenge for handling infection with this potential pathogen (Amoureux et al. 2012). According to recent studies, the resistance–nodulation–cell division-type efflux system and several β-lactamases appeared to be responsible for the resistance mechanisms (Bador et al. 2013, 2011; El Salabi et al. 2012; Yamamoto et al. 2012). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Members of the Achromobacter genus are Gram-negative bacteria including both environmental and clinical isolates, which are increasingly recovered from patients with cystic fibrosis (CF) as emerging pathogens. To better understand the features of the genus and its potential pathogenic mechanisms, six available Achromobacter genomes were compared in this study. The results revealed that: (1) Achromobacter had a pan-genome size of 10,750 genes with 3,398 core genes and a similar global classification of protein functions; (2) the Achromobacter genomes underwent a relatively low recombination that introduced nearly twice nucleotide substitutions less than the point mutation in genome evolution; (3) phylogenomic analysis based on 436 conserved proteins and average nucleotide identity both indicated that the Achromobacter genus had the closest relationship to the human/animal pathogen Bordetella rather than to Alcaligenes. The entire group of Achromobacter clustered with Bordetella in phylogeny, strongly suggesting a common origin, which therefore highlighted the potentially pathogenic nature of Achromobacter from the phylogenetic perspective, and (4) the CF clinical isolate possessed markedly unique genomic features discriminated from the environmental isolate and was equipped with numerous factors that facilitate its adaptation to a pathogenic lifestyle, such as a type III secretion system, a "polysaccharide island" (36.0 kb) of capsular/cellulose synthesis, adhesion-related proteins, alcaligin biogenesis, and several putative toxins. This study provided the first comprehensive genomic comparative analysis for Achromobacter, revealed information to better understand this far less-known genus on the genomic scale, and, importantly, identified potential virulence factors of the Achromobacter pathogen. (For more information Please see
    Applied Microbiology and Biotechnology 06/2013; DOI:10.1007/s00253-013-5018-3 · 3.34 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Acquired metallo-β-lactamases (MBLs) are resistance determinants of increasing clinical importance in Gram-negative bacterial pathogens, which confer a broad-spectrum β-lactam resistance, including carbapenems. Several such enzymes have been described since the 1990s. In the present study, a novel acquired MBL, named FIM-1, was identified and characterized. The blaFIM-1 gene was cloned from a multidrug-resistant Pseudomonas aeruginosa clinical isolate (FI-14/157) cultured from a patient with a vascular graft infection in Florence, Italy. The isolate belonged in the sequence type 235 epidemic clonal lineage. The FIM-1 enzyme is a member of subclass B1 and, among acquired MBLs, exhibited the highest similarity (ca. 40% amino acid identity) with NDM-type enzymes. In P. aeruginosa FI-14/157, the blaFIM-1 gene was apparently inserted into the chromosome and associated with ISCR19-like elements that were likely involved in the capture and mobilization of this MBL gene. Transfer experiments of the blaFIM-1 gene to an Escherichia coli strain or another P. aeruginosa strain by conjugation or electrotransformation were not successful. The FIM-1 protein was produced in E. coli and purified by two chromatography steps. Analysis of the kinetic parameters, carried out with the purified enzyme, revealed that FIM-1 has a broad substrate specificity, with a preference for penicillins (except the 6α-methoxy derivative temocillin) and carbapenems. Aztreonam was not hydrolyzed. Detection of this novel type of acquired MBL in a P. aeruginosa clinical isolate underscores the increasing diversity of such enzymes that can be encountered in the clinical setting.
    Antimicrobial Agents and Chemotherapy 10/2012; 57(1). DOI:10.1128/AAC.01953-12 · 4.48 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Context: Antibiotic resistance is an old problem with new face as the rate of infections due to multidrug resistant bacteria is increasing everyday and the number of new antibiotics to overwhelm the problem is becoming smaller. Major mechanism beneath this growing resistance is concomitant with the changes in β-lactamases catalytic activity and its functional enhancement. Objectives: In β-lactamases secreting clinical isolates at least 10% are extended-spectrum β-lactamases (ESBL) that are not even treatable with β-lactamases inhibitor like clavulanic acids. This implies that the catalytic domains of β-lactamases have been mutated towards higher pathogenicity. The aim of the present study is to define the changes in β-lactamases catalytic efficiency against β-lactam antibiotics and its inhibitors. Materials and Methods: In this research work we have used multiple drug resistant (MDR) strains from surgical site of infections. A rapid method was used for specific detection of bacterial β-lactamases that uses β-lactam antibiotics as substrates. In this, the end products (open beta-lactam ring forms) generated after separately incubating substrates with β-lactamases producing strains. Those end products of antibiotics were highly fluorescent after specific treatment and could be analyzed visually under long-wave UV lamp for efficiency. Results: β-lactamases secreting strains are variably capable of defending β-lactam antibiotics. Interestingly, one of the E. coli strain secretes ESBL, this means that the strain is resistant against clavulanic acid. However, the most fascinating fact of the finding is that ideally the β-lactamases supposed to hydrolyze Penicillin by default but in our isolates, β-lactamases are not able to hydrolyze penicillin instead they hydrolyze amoxicillin, a derivative which replaced clinical use of penicillin. In addition to that we have identified the presence of New Delhi Metalo- beta- lactamase in one of the clinical isolates. Conclusion: Rate of evolution in microbes is very high. Thus we presume that some of the amino acids in the functional domain of β-lactamases have been changed respective to extinct use of penicillin whereas it is effective against clinically used other beta lactam antibiotics.
    Journal of Bio-Science 12/2012; 19. DOI:10.3329/jbs.v19i0.12999
Show more