Laurent Poirel | Université de Fribourg (original) (raw)

Papers by Laurent Poirel

The extended-spectrum β-lactamase CTX-M-15 confers resistance to ceftazidime, unlike the majority... more The extended-spectrum β-lactamase CTX-M-15 confers resistance to ceftazidime, unlike the majority of CTX-M-type enzymes. Kinetic parameters were determined from purified CTX-M-15 and CTX-M-3, which differ by the single amino acid substitution Asp-240 to Gly, according to the Ambler numbering of class A β-lactamases. Relative molecular masses of CTX-M-15 and CTX-M-3 were ∼29 kDa and pI values were 8.9 and 8.4,

Antimicrob Agents Chemother, 2004

Enterobacter aerogenes clinical isolate LOR was resistant to penicillins and ceftazidime but susc... more Enterobacter aerogenes clinical isolate LOR was resistant to penicillins and ceftazidime but susceptible to cefuroxime, cephalothin, cefoxitin, cefotaxime, ceftriaxone, and cefepime. PCR and cloning experiments from this strain identified a novel TEM-type ␤-lactamase (TEM-121) differing by five amino acid substitutions from ␤-lactamase TEM-2 (Glu104Lys, Arg164Ser, Ala237Thr, Glu240Lys, and Arg244Ser) and by only one amino acid change from the extended-spectrum ␤-lactamase (ESBL) TEM-24 (Arg244Ser), with the last substitution also being identified in the inhibitor-resistant ␤-lactamase IRT-2. Kinetic parameters indicated that TEM-121 hydrolyzed ceftazidime and aztreonam (like TEM-24) and was inhibited weakly by clavulanic acid and strongly by tazobactam. Thus, TEM-121 is a novel complex mutant TEM ␤-lactamase (CMT-4) combining the kinetic properties of an ESBL and an inhibitor-resistant TEM enzyme.

Journal of Antimicrobial Chemotherapy, Jul 28, 2008

ABSTRACT Background: Emergence of infections due to multidrug-resistant Enterobacteriaceae presen... more ABSTRACT Background: Emergence of infections due to multidrug-resistant Enterobacteriaceae presents a significant public health problem worldwide. Treatment alternatives for infections due to carbapenemase-producing Enterobacteriaceae are few and the resistant organisms have the potential for causing serious healthcare epidemics if not promptly detected and contained. The study was conducted to investigate types of carbapenemases-encoded genes and drug resistance among carbapenem-resistant Enterobacteriaceae isolates in 6 government hospitals in Kuwait. Methods: Enterobacteriaceae isolates resistant to carbapenems were collected over a period of 3 years (2010-2013). Susceptibility testing to 13 commonly used antibiotics was carried out by E test according to the CLSI guidelines. PCR assay was performed for detection of genes encoding ESBLs (blaCTX-M, blaSHV and blaTEM) and carbapenemases (blaOXA-48, blaVIM, blaNDM, blaIMP, blaGIM and blaKPC). Results: A total of 66 non-duplicated carbapenem-resistant isolates were collected over a period of 3 years. However, only 32/66 (48.5%) carried the carbapenemase resistance genes. Resistance genes analysis showed that 11 isolates carried blaOXA-48 gene, 11 carried blaVIM-4 gene and 10 carried blaNDM-1 gene. 9.1%, 72 and 80 % of blaOXA-48, blaVIM-4 and blaNDM-1-carrying Enterobacteriaceae, respectively were resistant to amikacin. 27.3, 18.2 and 40 % of blaOXA-48, blaVIM-4 and blaNDM-1 carrying isolates, respectively, were resistant to tigecycline and 9.1, 9.1, and 20%, respectively to colistin. Overall, almost 70% of the isolates were resistant to ciprofloxacin and cefepime. Conclusion: Treatment of carbapenemase-producing Enterobacteriaeae in Kuwait is problematic as some of our isolates are resistant to tigecycline at an unacceptable level and resistance to colistin is emerging. Acknowledgement: Kuwait University Research Grant No. MI 06/10 is fully acknowledged.

Clin Microbiol Infect, 2008

Clinical Microbiology and Infection, Sep 1, 2007

macrolides, ketolides or quinolones was maintained against isolates of the four Spanish multiresi... more macrolides, ketolides or quinolones was maintained against isolates of the four Spanish multiresistant clones.

Diagnostic Microbiology and Infectious Disease, Jan 10, 2009

Two hundred fifty-seven nalidixic acid-resistant enterobacterial isolates were collected in a Bra... more Two hundred fifty-seven nalidixic acid-resistant enterobacterial isolates were collected in a Brazilian community from January 2000 to May 2005 to determine the prevalence of plasmid-encoded extended-spectrum β-lactamases. The bla CTX-M genetic environment was determined by polymerase chain reaction and sequencing. Eleven isolates (4.2%) harbored a bla CTX-M-2 gene, 3 isolates bla CTX-M-9 , 2 isolates bla CTX-M-8 , and 6 isolates bla SHV-5 . Two novel bla CTX-M-2 variants, namely, bla CTX-M-74 and bla CTX-M-75 , were identified.

Antimicrobial Agents and Chemotherapy, 2010

A Pseudomonas fluorescens isolate (PF-1) resistant to carbapenems was recovered during an environ... more A Pseudomonas fluorescens isolate (PF-1) resistant to carbapenems was recovered during an environmental survey performed with water from the Seine River (Paris). It expressed a novel Ambler class A carbapenemase, BIC-1, sharing 68 and 59% amino acid identities with ␤-lactamases SFC-1 from Serratia fonticola and the plasmid-encoded KPC-2, respectively. ␤-Lactamase BIC-1 hydrolyzed penicillins, carbapenems, and cephalosporins except ceftazidime and monobactams. The bla BIC-1 gene was chromosomally located and was also identified in two other P. fluorescens strains isolated from the Seine River 3 months later.

Clinical Microbiology and Infection Supplement, 2008

Extended-spectrum b-lactamases (ESBLs) are usually plasmid-mediated enzymes that confer resistanc... more Extended-spectrum b-lactamases (ESBLs) are usually plasmid-mediated enzymes that confer resistance to a broad range of b-lactams. Initially, resistance to third-generation cephalosporins in Gram-negative rods was mainly due to the dissemination of TEM-and SHV-type ESBLs, which are point mutants of the classic TEM and SHV enzymes with extended substrate specificity. During the last ten years, CTX-Mtype ESBLs have become increasingly predominant, but less frequent class A b-lactamases have also been described, including SFO, BES, BEL, TLA, GES, PER and VEB types. While several of these latter are rarely identified, or are very localised, others are becoming locally prevalent, or are increasingly isolated worldwide. In addition, mutations can extend the spectrum of some OXA-type b-lactamases to include expanded-spectrum cephalosporins, and several of these enzymes are considered to be ESBLs.

Antimicrobial Agents and Chemotherapy, Mar 1, 2002

As seen by the disk diffusion method, the clinical strain of Pseudomonas aeruginosa Pa695, resist... more As seen by the disk diffusion method, the clinical strain of Pseudomonas aeruginosa Pa695, resistant to all extended-spectrum cephalosporins and aminoglycosides, exhibited an unusual synergistic effect between ceftazidime and imipenem. This isolate produced an extended-spectrum beta-lactamase (ESBL) with a pI of 5.8 that appeared to be chromosomally encoded. Cloning experiments revealed that this ESBL was encoded by bla(GES-1), previously described in an integron from Klebsiella pneumoniae. In P. aeruginosa Pa695, a higher level of resistance to ceftazidime than to ticarcillin was observed, and no synergy between the beta-lactamase inhibitors and extended-spectrum cephalosporins was detected, in contrast to the resistance pattern observed in K. pneumoniae. Further sequence analysis demonstrated that the bla(GES-1) gene cassette was located in a class 1 integron, which contained another sequence corresponding to the fused aac3-Ib and aac6'-Ib' gene cassettes. The fusion product was functional, as was the product of each gene cloned separately: AAC3-I, despite the deletion of the four last amino acids, and AAC6', which carried three amino acid changes compared with the most homologous sequence. The AAC3-I protein conferred an expected gentamicin and fortimicin resistance, and the AAC6', despite the Leu-119-->Ser substitution, yielded resistance to kanamycin, tobramycin, and dibekacin, but slightly affected netilmicin and amikacin, and had no apparent effect on gentamicin. The fusion product conveyed a large profile of resistance, combining the AAC6' activity with a higher level of gentamicin resistance without accompanying fortimicin resistance.

Antimicrob Agents Chemother, 2008

A chromosomally encoded class D ␤-lactamase, OXA-114, was characterized from Achromobacter xyloso... more A chromosomally encoded class D ␤-lactamase, OXA-114, was characterized from Achromobacter xylosoxidans strain CIP69598. ␤-Lactamase OXA-114 shared 56% amino acid identity with the naturally occurring class D ␤-lactamase of Burkholderia cenocepacia and 42% identity with the acquired oxacillinases OXA-9 and OXA-18. OXA-114 has a narrow-spectrum hydrolysis profile, although it includes imipenem, at a very low level. PCR and sequencing revealed that bla OXA-114 -like genes were identified in all A. xylosoxidans strains tested (n ‫؍‬ 5), indicating that this ␤-lactamase is naturally occurring in that species. Induction experiments with imipenem and cefoxitin did not show inducibility of bla OXA-114 expression.

Antimicrob Agents Chemother, 2000

In vitro synergy between extended-spectrum cephalosporins and either clavulanic acid or cefoxitin... more In vitro synergy between extended-spectrum cephalosporins and either clavulanic acid or cefoxitin was found for Chryseobacterium meningosepticum isolates during a double-disk assay on an agar plate. An extendedspectrum ␤-lactamase (ESBL) gene from a C. meningosepticum clinical isolate was cloned and expressed in Escherichia coli DH10B. Its protein conferred resistance to most ␤-lactams including extended-spectrum cephalosporins but not to cephamycins or to imipenem. Its activity was strongly inhibited by clavulanic acid, sulbactam, and tazobactam, as well as by cephamycins and imipenem. Sequence analysis of the cloned DNA fragment revealed an open reading frame (ORF) of 891 bp with a G؉C content of 33.9%, which lies close to the expected range of G؉C contents of members of the Chryseobacterium genus. The ORF encoded a precursor protein of 297 amino acids, giving a mature protein with a molecular mass of 31 kDa and a pI value of 9.2 in E. coli. This gene was very likely chromosomally located. Amino acid sequence comparison showed that this ␤-lactamase, named CME-2 (C. meningosepticum ESBL), is a novel ESBL of the Ambler class A group (Bush functional group 2be), being weakly related to other class A ␤-lactamases. It shares only 39 and 35% identities with the ESBLs VEB-1 from E. coli MG-1 and CBL-A from Bacteroides uniformis, respectively. The distribution of bla CME-2 among unrelated C. meningosepticum species isolates showed that bla CME-2 -like genes were found in the C. meningosepticum strains studied but were absent from strains of other C. meningosepticum-related species. Each C. meningosepticum strain produced at least two ␤-lactamases, with one of them being a noninducible serine ESBL with variable pIs ranging from 7.0 to 8.5.

Antimicrobial Agents and Chemotherapy, Oct 1, 2010

A chromosomally located -lactamase gene, cloned and expressed in Escherichia coli from a referenc... more A chromosomally located -lactamase gene, cloned and expressed in Escherichia coli from a reference strain of the enterobacterial species Kluyvera cryocrescens, encoded a clavulanic acid-inhibited Ambler class A enzyme, KLUC-1, with a pI value of 7.4. KLUC-1 shared 86% amino acid identity with a subgroup of plasmid-mediated CTX-M-type extended-spectrum -lactamases (CTX-M-1, -3, -10, -11, and -12), the most closely related