scholarly journals A Novel Class A Extended-Spectrum β-Lactamase (BES-1) in Serratia marcescens Isolated in Brazil

2000 ◽  
Vol 44 (11) ◽  
pp. 3061-3068 ◽  
Author(s):  
R. Bonnet ◽  
J. L. M. Sampaio ◽  
C. Chanal ◽  
D. Sirot ◽  
C. De Champs ◽  
...  
Keyword(s):  
Serratia Marcescens ◽  
Functional Group ◽  
Inhibitory Concentration ◽  
Structural Features ◽  
Cloning And Sequencing ◽  
Gene Encoding ◽  
Class A ◽  
Extended Spectrum ◽  
Related Enzyme ◽  
High Level

ABSTRACT Serratia marcescens Rio-5, one of 18 extended-spectrum β-lactamase (ESBL)-producing strains isolated in several hospitals in Rio de Janeiro (Brazil) in 1996 and 1997, exhibited a high level of resistance to aztreonam (MIC, 512 μg/ml) and a distinctly higher level of resistance to cefotaxime (MIC, 64 μg/ml) than to ceftazidime (MIC, 8 μg/ml). The strain produced a plasmid-encoded ESBL with a pI of 7.5 whose bla gene was not related to those of other plasmid-mediated Ambler class A ESBLs. Cloning and sequencing revealed a bla gene encoding a novel class A β-lactamase in functional group 2be, designated BES-1 (Brazil extended-spectrum β-lactamase). This enzyme had 51% identity with chromosomal class A penicillinase of Yersinia enterocolitica Y56, which was the most closely related enzyme and 47 to 48% identity with CTX-M-type β-lactamases, which were the most closely related ESBLs. In common with CTX-M enzymes, BES-1 exhibited high cefotaxime-hydrolyzing activity (k cat, 425 s−1). However, BES-1 differed from CTX-M enzymes by its significant ceftazidime-hydrolyzing activity (k cat, 25 s−1), high affinity for aztreonam (Ki , 1 μM), and lower susceptibility to tazobactam (50% inhibitory concentration [IC50], 0.820 μM) than to clavulanate (IC50, 0.045 μM). Likewise, certain characteristic structural features of CTX-M enzymes, such as Phe-160, Ser-237, and Arg-276, were observed for BES-1, which, in addition, harbored different residues (Ala-104, Ser-171, Arg-220, Gly-240) and six additional residues at the end of the sequence. BES-1, therefore, may be an interesting model for further investigations of the structure-function relationships of class A ESBLs.

scholarly journals Identification of the Novel Narrow-Spectrum β-Lactamase SCO-1 in Acinetobacter spp. from Argentina

2007 ◽  
Vol 51 (6) ◽  
pp. 2179-2184 ◽  
Author(s):  
Laurent Poirel ◽  
Stéphane Corvec ◽  
Melina Rapoport ◽  
Pauline Mugnier ◽  
Alejandro Petroni ◽  
...  
Keyword(s):  
Amino Acid Identity ◽  
The Novel ◽  
Gene Encoding ◽  
Class A ◽  
Narrow Spectrum ◽  
A Value ◽  
Acinetobacter Spp ◽  
Encoding Gene ◽  
High Level ◽  
Lactamase Gene

ABSTRACT By studying the β-lactamase content of several Acinetobacter spp. isolates from Argentina, producing the expanded-spectrum β-lactamases (ESBL) VEB-1a or PER-2, a novel Ambler class A β-lactamase gene was identified. It encoded the narrow-spectrum β-lactamase SCO-1, whose activity was inhibited by clavulanic acid. SCO-1 hydrolyzes penicillins at a high level and cephalosporins and carbapenems at a very low level. β-Lactamase SCO-1 was identified from unrelated VEB-1a-positive or PER-2-positive Acinetobacter spp. isolates recovered from three hospitals. The bla SCO-1 gene was apparently located on a plasmid of ca. 150 kb from all cases but was not associated with any ESBL-encoding gene. The G+C content of the bla SCO gene was 52%, a value that does not correspond to that of the A. baumannii genome (39%). β-Lactamase SCO-1 shares 47% amino acid identity with CARB-5 and ca. 40% with the enzymes TEM, SHV, and CTX-M. A gene encoding a putative resolvase was identified downstream of the bla SCO-1 gene, but its precise way of acquisition remains to be determined.

scholarly journals Mutation in Serratia marcescens AmpC β-Lactamase Producing High-Level Resistance to Ceftazidime and Cefpirome

2001 ◽  
Vol 45 (8) ◽  
pp. 2331-2339 ◽  
Author(s):  
Alessandro Raimondi ◽  
Francesca Sisto ◽  
Hiroshi Nikaido
Keyword(s):  
Serratia Marcescens ◽  
Catalytic Efficiency ◽  
Fold Increase ◽  
Mutant Enzyme ◽  
Kinetic Properties ◽  
Cloning And Sequencing ◽  
Mutant Strains ◽  
High Level ◽  
Outer Membrane Permeability ◽  
Level Resistance

ABSTRACT Starting from a clinical isolate of Serratia marcescens that produced a chromosomally encoded AmpC β-lactamase inducibly, we isolated by stepwise selection two laboratory mutants that showed high levels of resistance to some cephalosporins. The 98R mutant apparently overproduced the unaltered β-lactamase constitutively, but the 520R mutant produced an altered enzyme, also constitutively. Ceftazidime and cefpirome MICs for the 520R mutant were much higher (512 and 64 μg/ml, respectively) than those for the 98R mutant (16 and 16 μg/ml, respectively). Yet the MICs of cephaloridine and piperacillin for the 520R mutant were four- to eightfold lower than those for the 98R mutant. Cloning and sequencing of theampC alleles showed that in the 520R mutant enzyme, the Thr64 residue, about two turns away from the active-site serine, was mutated to isoleucine. This resulted in a >1,000-fold increase in the catalytic efficiency (k cat/K m ) of the mutated AmpC enzyme toward ceftazidime, whereas there was a >10-fold decrease in the efficiency of the mutant enzyme toward cefazolin and cephaloridine. The outer membrane permeability of the 520R strain to cephalosporins was also less than in the 98R strain, and the alteration of the kinetic properties of the AmpC enzyme together with this difference in permeability explained quantitatively the resistance levels of both mutant strains to most agents studied.

scholarly journals Genetic and Biochemical Characterization of CAD-1, a Chromosomally Encoded New Class A Penicillinase from Carnobacterium divergens

2007 ◽  
Vol 52 (2) ◽  
pp. 551-556 ◽  
Author(s):  
Djalal Meziane-Cherif ◽  
Dominique Decré ◽  
E. Arne Høiby ◽  
Patrice Courvalin ◽  
Bruno Périchon
Keyword(s):  
Clavulanic Acid ◽  
Mobile Genetic Element ◽  
Inhibitory Concentration ◽  
Biochemical Characterization ◽  
Cloning And Sequencing ◽  
New Class ◽  
Class A ◽  
Amoxicillin Clavulanic Acid ◽  
Carnobacterium Divergens

ABSTRACT Carnobacterium divergens clinical isolates BM4489 and BM4490 were resistant to penicillins but remained susceptible to combinations of amoxicillin-clavulanic acid and piperacillin-tazobactam. Cloning and sequencing of the responsible determinant from BM4489 revealed a coding sequence of 912 bp encoding a class A β-lactamase named CAD-1. The bla CAD-1 gene was assigned to a chromosomal location in the two strains that had distinct pulsed-field gel electrophoresis patterns. CAD-1 shared 53% and 42% identity with β-lactamases from Bacillus cereus and Staphylococcus aureus, respectively. Alignment of CAD-1 with other class A β-lactamases indicated the presence of 25 out of the 26 isofunctional amino acids in class A β-lactamases. Escherichia coli harboring bla CAD-1 exhibited resistance to penams (benzylpenicillin and amoxicillin) and remained susceptible to amoxicillin in combination with clavulanic acid. Mature CAD-1 consisted of a 34.4-kDa polypeptide. Kinetic analysis indicated that CAD-1 exhibited a narrow substrate profile, hydrolyzing benzylpenicillin, ampicillin, and piperacillin with catalytic efficiencies of 6,600, 3,200, and 2,900 mM−1 s−1, respectively. The enzyme did not interact with oxyiminocephalosporins, imipenem, or aztreonam. CAD-1 was inhibited by tazobactam (50% inhibitory concentration [IC50] = 0.27 μM), clavulanic acid (IC50 = 4.7 μM), and sulbactam (IC50 = 43.5 μM). The bla CAD-1 gene is likely to have been acquired by BM4489 and BM4490 as part of a mobile genetic element, since it was not found in the susceptible type strain CIP 101029 and was adjacent to a gene for a resolvase.

scholarly journals CMT-Type β-Lactamase TEM-125, an Emerging Problem for Extended-Spectrum β-Lactamase Detection

2006 ◽  
Vol 50 (7) ◽  
pp. 2403-2408 ◽  
Author(s):  
Frédéric Robin ◽  
Julien Delmas ◽  
Maryse Archambaud ◽  
Cédric Schweitzer ◽  
Catherine Chanal ◽  
...  
Keyword(s):  
Inhibitory Concentration ◽  
Clinical Laboratory ◽  
Hydrolytic Activity ◽  
Detection Methods ◽  
Clinical Strain ◽  
National Guidelines ◽  
French Society ◽  
Extended Spectrum ◽  
Need To Evaluate ◽  
High Level

ABSTRACT The clinical strain Escherichia coli TO799 was resistant to penicillin-clavulanate combinations and ceftazidime and was not reproducibly detected as an extended-spectrum β-lactamase (ESBL) according to the standards of the Clinical Laboratory Standards Institute (CLSI; formerly NCCLS) and the national guidelines of the French Society for Microbiology (Comité de l'Antibiogramme de la Société Française de Microbiologie). A novel β-lactamase, designated TEM-125, was responsible for this phenotype. TEM-125 harbors a complex association of mutations previously described in the ESBL TEM-12 and in the inhibitor-resistant β-lactamase TEM-39. TEM-125 is the first complex mutant TEM to present hydrolytic activity against ceftazidime (k cat, 3.7 s−1) together with a high level of resistance to clavulanate (50% inhibitory concentration, 13.6 μM). The discovery of such an ESBL, which is difficult to detect by the usual ESBL detection methods, confirms the emergence of a complex mutant TEM subgroup and highlights the need to evaluate detection methods so as to avoid possible therapeutic failures.

scholarly journals Interactions of β-Lactamases with Sanfetrinem (GV 104326) Compared to Those with Imipenem and with Oral β-Lactams

1998 ◽  
Vol 42 (5) ◽  
pp. 1168-1175 ◽  
Author(s):  
Gioia S. Babini ◽  
Meifang Yuan ◽  
David M. Livermore
Keyword(s):  
Functional Group ◽  
Klebsiella Oxytoca ◽  
Enterobacter Cloacae ◽  
Proteus Vulgaris ◽  
Morganella Morganii ◽  
Full Activity ◽  
Class A ◽  
Extended Spectrum ◽  
Class B ◽  
Hydrolysis Of

ABSTRACT Sanfetrinem is a trinem β-lactam which can be administered orally as a hexatil ester. We examined whether its β-lactamase interactions resembled those of the available carbapenems, i.e., stable to AmpC and extended-spectrum β-lactamases but labile to class B and functional group 2f enzymes. The comparator drugs were imipenem, oral cephalosporins, and amoxicillin. MICs were determined for β-lactamase expression variants, and hydrolysis was examined directly with representative enzymes. Sanfetrinem was a weak inducer of AmpC β-lactamases below the MIC and had slight lability, with ak cat of 0.00033 s−1 for theEnterobacter cloacae enzyme. Its MICs for AmpC-derepressedE. cloacae and Citrobacter freundii were 4 to 8 μg/ml, compared with MICs of 0.12 to 2 μg/ml for AmpC-inducible and -basal strains; MICs for AmpC-derepressed Serratia marcescens and Morganella morganii were not raised. Cefixime and cefpodoxime were more labile than sanfetrinem to theE. cloacae AmpC enzyme, and AmpC-derepressed mutants showed much greater resistance; imipenem was more stable and retained full activity against derepressed mutants. Like imipenem, sanfetrinem was stable to TEM-1 and TEM-10 enzymes and retained full activity against isolates and transconjugants with various extended-spectrum TEM and SHV enzymes, whereas these organisms were resistant to cefixime and cefpodoxime. Sanfetrinem, like imipenem and cefixime but unlike cefpodoxime, also retained activity against Proteus vulgaris and Klebsiella oxytoca strains that hyperproduced potent chromosomal class A β-lactamases. Functional group 2f enzymes, including Sme-1, NMC-A, and an unnamed enzyme fromAcinetobacter spp., increased the sanfetrinem MICs by up to 64-fold. These enzymes also compromised the activities of imipenem and amoxicillin but not those of the cephalosporins. The hydrolysis of sanfetrinem was examined with a purified Sme-1 enzyme, and biphasic kinetics were found. Finally, zinc β-lactamases, including IMP-1 and the L1 enzyme of Stenotrophomonas maltophilia, conferred resistance to sanfetrinem and all other β-lactams tested, and hydrolysis was confirmed with the IMP-1 enzyme. We conclude that sanfetrinem has β-lactamase interactions similar to those of the available carbapenems except that it is a weaker inducer of AmpC types, with some tendency to select derepressed mutants, unlike imipenem and meropenem.

scholarly journals Chromosome-Encoded Extended-Spectrum Class A β-Lactamase MIN-1 from Minibacterium massiliensis

2012 ◽  
Vol 56 (7) ◽  
pp. 4009-4012 ◽  
Author(s):  
Béatrice Bercot ◽  
Patrice Nordmann ◽  
Michel Drancourt ◽  
Laurent Poirel
Keyword(s):  
Amino Acid ◽  
Water Samples ◽  
Gene Encoding ◽  
Gram Negative ◽  
Content Type ◽  
Class A ◽  
Narrow Spectrum ◽  
Extended Spectrum

ABSTRACTMinibacterium massiliensisstrain CIP107820 is a recently discovered waterborne Gram-negative rod isolated from hospital water samples. It harbors a chromosomally located gene encoding an Ambler class A extended-spectrum β-lactamase termed MIN-1, sharing 56%, 54%, and 51% amino acid identities with β-lactamases LUT-1, KPC-2, and CTX-M-2, respectively. β-Lactamase MIN-1 hydrolyzes penicillins, narrow-spectrum cephalosporins, cefotaxime, and, less efficiently, cefepime, while ceftazidime and carbapenems are very poor substrates, and cephamycins and aztreonam are not hydrolyzed.

scholarly journals Association between 16S rRNA gene mutations and susceptibility to amikacin in Mycobacterium avium Complex and Mycobacterium abscessus clinical isolates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Su-Young Kim ◽  
Dae Hun Kim ◽  
Seong Mi Moon ◽  
Ju Yeun Song ◽  
Hee Jae Huh ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Mycobacterium Avium ◽  
Inhibitory Concentration ◽  
Gene Mutations ◽  
Mycobacterium Abscessus ◽  
Clinical Isolates ◽  
Rrna Gene ◽  
High Level ◽  
Culture Conversion

AbstractWe evaluated the association between 16S rRNA gene (rrs) mutations and susceptibility in clinical isolates of amikacin-resistant nontuberculous mycobacteria (NTM) in NTM-pulmonary disease (PD) patients. Susceptibility was retested for 134 amikacin-resistant isolates (minimum inhibitory concentration [MIC] ≥ 64 µg/ml) from 86 patients. Amikacin resistance was reconfirmed in 102 NTM isolates from 62 patients with either Mycobacterium avium complex-PD (MAC-PD) (n = 54) or M. abscessus-PD (n = 8). MICs and rrs mutations were evaluated for 318 single colonies from these isolates. For the 54 MAC-PD patients, rrs mutations were present in 34 isolates (63%), comprising all 31 isolates with amikacin MICs ≥ 128 µg/ml, but only three of 23 isolates with an MIC = 64 µg/ml. For the eight M. abscessus-PD patients, all amikacin-resistant (MIC ≥ 64 µg/ml) isolates had rrs mutations. In amikacin-resistant isolates, the A1408G mutation (n = 29) was most common. Two novel mutations, C1496T and T1498A, were also identified. The culture conversion rate did not differ by amikacin MIC. Overall, all high-level and 13% (3/23) of low-level amikacin-resistant MAC isolates had rrs mutations whereas mutations were present in all amikacin-resistant M. abscessus isolates. These findings are valuable for managing MAC- and M. abscessus-PD and suggest the importance of phenotypic and genotypic susceptibility testing.

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