scholarly journals Diversity of TEM Mutants in Proteus mirabilis

1999 ◽  
Vol 43 (11) ◽  
pp. 2671-2677 ◽  
Author(s):  
R. Bonnet ◽  
C. De Champs ◽  
D. Sirot ◽  
C. Chanal ◽  
R. Labia ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Proteus Mirabilis ◽  
Clinical Isolates ◽  
Amino Acid Substitutions ◽  
First Report ◽  
Conjugative Plasmids ◽  
Extended Spectrum ◽  
Nucleotide Mutation

ABSTRACT In a survey of resistance to amoxicillin among clinical isolates ofProteus mirabilis, 10 TEM-type β-lactamases were characterized: (i) the well-known penicillinases TEM-1 and TEM-2, the extended-spectrum β-lactamases (ESBLs) TEM-3 and TEM-24, and the inhibitor-resistant TEM (IRT) TEM-44 and (ii) five novel enzymes, a penicillinase TEM-57 similar to TEM-1, an ESBL TEM-66 similar to TEM-3, and three IRTs, TEM-65, TEM-73, and TEM-74. The penicillinase TEM-57 and the ESBL TEM-66 differed from TEM-1 and TEM-3, respectively, by the amino acid substitution Gly-92→Asp (nucleotide mutation G-477→A). This substitution could have accounted for the decrease in pIs (5.2 for TEM-57 and 6.0 for TEM-66) but did not necessarily affect the intrinsic activities of these enzymes. The IRT TEM-65 was an IRT-1-like IRT (Cys-244) related to TEM-2 (Lys-39). The two other IRTs, TEM-73 and TEM-74, were related to IRT-1 (Cys-244) and IRT-2 (Ser-244), respectively, and harbored the amino acid substitutions Leu-21→Phe and Thr-265→Met. In this study, the ESBLs TEM-66, TEM-24, and TEM-3 were encoded by large (170- to 180-kb) conjugative plasmids that exhibited similar patterns after digestion and hybridization with the TEM and AAC(6′)I probes. The three IRTs TEM-65, TEM-73, and TEM-74 were encoded by plasmids that ranged in size from 42 to 70 kb but for which no transfer was obtained. The characterization of five new plasmid-mediated TEM-type β-lactamases and the first report of TEM-24 in P. mirabilis are evidence of the wide diversity of β-lactamases produced in this species and of its possible role as a β-lactamase-encoding plasmid reservoir.

First Detection of OXA-10 Extended-Spectrum Beta-Lactamases and the Occurrence of mexR and nfxB in Clinical Isolates of Pseudomonas aeruginosa from Nigeria

Chemotherapy ◽  
2015 ◽  
Vol 61 (2) ◽  
pp. 87-92 ◽  
Author(s):  
Bamidele T. Odumosu ◽  
Bola A. Adeniyi ◽  
Ram Chandra
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Clinical Isolates ◽  
Beta Lactamases ◽  
First Report ◽  
Extended Spectrum ◽  
Pcr Rflp ◽  
Extended Spectrum Beta Lactamases ◽  
Regulator Genes

Background: The characterization of β-lactamase production in Pseudomonasaeruginosa is rarely reported in Nigeria. The objective of this study was to investigate the occurrence and characterize the different β-lactamases as well as mechanisms of fluoroquinolones resistance among P. aeruginosa isolated from various clinical sources from Nigeria. Materials and Method: Isolates were investigated using PCR, RFLP and sequencing for the detection of various β-lactamases and efflux pump regulator genes. Result: The prevalence of OXA-10, AmpC, CTX-M and SHV in P. aeruginosa was 80, 70, 5 and 5%, respectively. The coexistence of blaOXA-10 with blaAmpC, blaSHV and blaCTX-M was reported in 40, 5 and 5% of isolates, respectively. The efflux pump regulator genes mexR and nfxB were both amplified in 45% of the OXA-10-positive isolates. Conclusion: This is the first report of the characterization of OXA-10 extended-spectrum β-lactamases and occurrence of mexR and nfxB efflux regulator genes in clinical isolates of P. aeruginosa in Nigeria.

scholarly journals TEM-72, a New Extended-Spectrum β-Lactamase Detected in Proteus mirabilis and Morganella morganii in Italy

2000 ◽  
Vol 44 (9) ◽  
pp. 2537-2539 ◽  
Author(s):  
Mariagrazia Perilli ◽  
Bernardetta Segatore ◽  
Maria Rosaria De Massis ◽  
Maria Letizia Riccio ◽  
Ciro Bianchi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Kinetic Analysis ◽  
Proteus Mirabilis ◽  
Host Susceptibility ◽  
Amino Acid Substitutions ◽  
Morganella Morganii ◽  
Extended Spectrum ◽  
Spectrum Activity

ABSTRACT A new natural TEM-2 derivative, named TEM-72, was identified in aProteus mirabilis strain and in a Morganella morganii strain isolated in Italy in 1999. Compared to TEM-1, TEM-72 contains the following amino acid substitutions: Q39K, M182T, G238S, and E240K. Kinetic analysis showed that TEM-72 exhibits an extended-spectrum activity, including activity against oxyimino-cephalosporins and aztreonam. Expression ofbla TEM-72 in Escherichia coli was capable of decreasing the host susceptibility to the above drugs.

scholarly journals Survey of Enterobacteriaceae Producing Extended-Spectrum β-Lactamases in a Slovak Hospital: Dominance of SHV-2a and Characterization of TEM-132

2005 ◽  
Vol 49 (7) ◽  
pp. 3066-3069 ◽  
Author(s):  
Martina Zarnayová ◽  
Eliane Siebor ◽  
André Péchinot ◽  
Jean-Marie Duez ◽  
Helena Bujdáková ◽  
...  
Keyword(s):  
Amino Acid ◽  
Kinetic Properties ◽  
Amino Acid Substitutions ◽  
Extended Spectrum

ABSTRACT Eighty-five extended-spectrum β-lactamase-producing Enterobacteriaceae from a Slovak hospital have been studied. SHV-2a was predominant, but other variants have been detected, namely, SHV-5, SHV-12, TEM-12, TEM-15, and TEM-132, which differed from TEM-1 by amino acid substitutions R164H, E240K, and I173V and had kinetic properties similar to those of TEM-28.

scholarly journals Capnocytophaga ochracea: Characterization of a Plasmid-Encoded Extended-Spectrum TEM-17 β-Lactamase in the Phylum Flavobacter-Bacteroides

2000 ◽  
Vol 44 (3) ◽  
pp. 760-762 ◽  
Author(s):  
Agnes Rosenau ◽  
Blandine Cattier ◽  
Nathalie Gousset ◽  
Patrick Harriau ◽  
Alain Philippon ◽  
...  
Keyword(s):  
Amino Acid ◽  
Clinical Isolate ◽  
Amino Acid Substitution ◽  
Single Amino Acid Substitution ◽  
Single Amino Acid ◽  
Extended Spectrum

ABSTRACT A plasmid-encoded extended-spectrum TEM β-lactamase with a pI of 5.5 was detected in a Capnocytophaga ochracea clinical isolate. The bla gene was associated with a strong TEM-2 promoter and was derived from bla TEM-1a with a single-amino-acid substitution: Glu104→Lys, previously assigned to TEM-17, which is thus the first TEM β-lactamase to be reported in the phylum Flavobacter-Bacteroides.

scholarly journals Construction and Characterization of Mutants of the TEM-1 β-Lactamase Containing Amino Acid Substitutions Associated with both Extended-Spectrum Resistance and Resistance to β-Lactamase Inhibitors

1999 ◽  
Vol 43 (8) ◽  
pp. 1881-1887 ◽  
Author(s):  
Paul D. Stapleton ◽  
Kevin P. Shannon ◽  
Gary L. French
Keyword(s):  
Amino Acid ◽  
Site Directed Mutagenesis ◽  
Amino Acid Substitutions ◽  
Extended Spectrum ◽  
Double Substitution ◽  
Inhibitor Resistance ◽  
Reduced Activity ◽  
Hybrid Enzymes ◽  
Increased Susceptibility

ABSTRACT Extended-spectrum TEM β-lactamases (ESBLs) do not usually confer resistance to β-lactamase inhibitors such as clavulanate or tazobactam. To investigate the compatibility of the two phenotypes we used site-directed mutagenesis of the bla TEM-1gene to introduce into the TEM-1 β-lactamase amino acid substitutions that confer the ESBL phenotype: TEM-12 (Arg164→Ser), TEM-26 (Arg164→Ser plus Glu104→Lys), TEM-19 (Gly238→Ser), and TEM-15 (Gly238→Ser plus Glu104→Lys). These were combined with three sets of substitutions that confer inhibitor resistance: TEM-31 (Arg244→Cys), TEM-33 (Met69→Leu), and TEM-35 (Met69→Leu and Asn276→Asp). Introduction of the Arg244→Cys substitution gave rise to inhibitor-resistant hybrid enzymes that either lost ESBL activity (TEM-12, TEM-15, and TEM-19) or had reduced activity (TEM-26) against ceftazidime. In contrast, the introduction of Met69→Leu or Met69→Leu plus Asn276→Asp substitutions did not significantly affect the abilities of the enzymes to confer resistance to ceftazidime, although increased susceptibility to cefotaxime was observed with Escherichia coli strains that expressed the TEM-19 and TEM-26 β-lactamases. With the exception of the TEM-12 β-lactamase, introduction of the Met69→Leu substitution did not give rise to enzymes with increased resistance to clavulanate compared to that of the TEM-1 β-lactamase. However, introduction of the double substitution Met69→Leu plus Asn276→Asp in the ESBLs did give rise to low-level (TEM-19, TEM-15, and TEM-26) or moderate-level (TEM-12) clavulanate resistance. None of the hybrid enzymes were as resistant to clavulanate as the corresponding inhibitor-resistant TEM β-lactamase mutant, suggesting that active-site configuration in the ESBLs limits the degree of clavulanate resistance conferred.

scholarly journals Contribution of Clinically Derived Mutations inERG11to Azole Resistance in Candida albicans

2014 ◽  
Vol 59 (1) ◽  
pp. 450-460 ◽  
Author(s):  
Stephanie A. Flowers ◽  
Brendan Colón ◽  
Sarah G. Whaley ◽  
Mary A. Schuler ◽  
P. David Rogers
Keyword(s):  
Candida Albicans ◽  
Amino Acid ◽  
Amino Acid Substitution ◽  
Single Amino Acid Substitution ◽  
Clinical Isolates ◽  
Single Amino Acid ◽  
Azole Resistance ◽  
Amino Acid Substitutions ◽  
Content Type ◽  
Proximal Surface

ABSTRACTInCandida albicans, theERG11gene encodes lanosterol demethylase, the target of the azole antifungals. Mutations inERG11that result in an amino acid substitution alter the abilities of the azoles to bind to and inhibit Erg11, resulting in resistance. AlthoughERG11mutations have been observed in clinical isolates, the specific contributions of individualERG11mutations to azole resistance inC. albicanshave not been widely explored. We sequencedERG11in 63 fluconazole (FLC)-resistant clinical isolates. Fifty-five isolates carried at least one mutation inERG11, and we observed 26 distinct positions in which amino acid substitutions occurred. We mapped the 26 distinct variant positions in these alleles to four regions in the predicted structure for Erg11, including its predicted catalytic site, extended fungus-specific external loop, proximal surface, and proximal surface-to-heme region. In total, 31 distinctERG11alleles were recovered, with 10ERG11alleles containing a single amino acid substitution. We then characterized 19 distinctERG11alleles by introducing them into the wild-type azole-susceptibleC. albicansSC5314 strain and testing them for susceptibilities to FLC, itraconazole (ITC), and voriconazole (VRC). The strains that were homozygous for the single amino acid substitutions Y132F, K143R, F145L, S405F, D446E, G448E, F449V, G450E, and G464S had a ≥4-fold increase in FLC MIC. The strains that were homozygous for several double amino acid substitutions had decreased azole susceptibilities beyond those conferred by any single amino acid substitution. These findings indicate that mutations inERG11are prevalent among azole-resistant clinical isolates and that most mutations result in appreciable changes in FLC and VRC susceptibilities.

scholarly journals Carbapenem Resistance Mechanisms in Pseudomonas aeruginosa Clinical Isolates

2001 ◽  
Vol 45 (2) ◽  
pp. 480-484 ◽  
Author(s):  
Hyunjoo Pai ◽  
Jong-Won Kim ◽  
Jungmin Kim ◽  
Ji Hyang Lee ◽  
Kang Won Choe ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Amino Acid Substitution ◽  
Carbapenem Resistance ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Efflux System ◽  
Clinical Strains ◽  
Carbapenem Resistant

ABSTRACT In order to define the contributions of the mechanisms for carbapenem resistance in clinical strains of Pseudomonas aeruginosa, we investigated the presence of OprD, the expressions of the MexAB-OprM and MexEF-OprN systems, and the production of the β-lactamases for 44 clinical strains. All of the carbapenem-resistant isolates showed the loss of or decreased levels of OprD. Three strains overexpressed the MexAB-OprM efflux system by carrying mutations inmexR. These three strains had the amino acid substitution in MexR protein, Arg (CGG) → Gln (CAG), at the position of amino acid 70. None of the isolates, however, expressed the MexEF-OprN efflux system. For the characterization of β-lactamases, at least 13 isolates were the depressed mutants, and 12 strains produced secondary β-lactamases. Based on the above resistance mechanisms, the MICs of carbapenem for the isolates were analyzed. The MICs of carbapenem were mostly determined by the expression of OprD. The MICs of meropenem were two- to four-fold increased for the isolates which overexpressed MexAB-OprM in the background of OprD loss. However, the elevated MICs of meropenem for some individual isolates could not be explained. These findings suggested that other resistance mechanisms would play a role in meropenem resistance in clinical isolates of P. aeruginosa.

scholarly journals Mutations in the gyrA, parC, and parE Genes Associated with Fluoroquinolone Resistance in Clinical Isolates of Mycoplasma hominis

1999 ◽  
Vol 43 (4) ◽  
pp. 954-956 ◽  
Author(s):  
Cécile M. Bebear ◽  
Joel Renaudin ◽  
Alain Charron ◽  
Hélène Renaudin ◽  
Bertille de Barbeyrac ◽  
...  
Keyword(s):  
Amino Acid ◽  
Mycoplasma Hominis ◽  
Dna Gyrase ◽  
Quinolone Resistance ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Amino Acid Substitutions ◽  
Topoisomerase Iv

ABSTRACT Five clinical isolates of Mycoplasma hominis from three different patients were examined for resistance to fluoroquinolones; some of these isolates were probably identical. All five isolates harbored amino acid substitutions in the quinolone resistance-determining regions of both DNA gyrase (GyrA) and topoisomerase IV (ParC or ParE). Furthermore, the novobiocin MIC for three isolates showed a significant increase. This is the first characterization of fluoroquinolone-resistant clinical mycoplasma isolates from humans.

scholarly journals Fluoroquinolone Resistance in Clinical Isolates ofStreptococcus pneumoniae: Contributions of Type II Topoisomerase Mutations and Efflux to Levels of Resistance

2000 ◽  
Vol 44 (11) ◽  
pp. 3049-3054 ◽  
Author(s):  
Darrin J. Bast ◽  
Donald E. Low ◽  
Carla L. Duncan ◽  
Laurie Kilburn ◽  
Lionel A. Mandell ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Amino Acid Substitutions ◽  
Type Ii ◽  
Low Level ◽  
High Level ◽  
The Impact ◽  
Level Resistance

ABSTRACT We report on amino acid substitutions in the quinolone resistance-determining region of type II topisomerases and the prevalence of reserpine-inhibited efflux for 70 clinical isolates ofS. pneumoniae for which the ciprofloxacin MIC is ≥4 μg/ml and 28 isolates for which the ciprofloxacin MIC is ≤2 μg/ml. The amino acid substitutions in ParC conferring low-level resistance (MICs, 4 to 8 μg/ml) included Phe, Tyr, and Ala for Ser-79; Asn, Ala, Gly, Tyr, and Val for Asp-83; Asn for Asp-78; and Pro for Ala-115. Isolates with intermediate-level (MICs, 16 to 32 μg/ml) and high-level (MICs, 64 μg/ml) resistance harbored substitutions of Phe and Tyr for Ser-79 or Asn and Ala for Asp-83 in ParC and an additional substitution in GyrA which included either Glu-85-Lys (Gly) or Ser-81-Phe (Tyr). Glu-85-Lys was found exclusively in isolates with high-level resistance. Efflux contributed primarily to low-level resistance in isolates with or without an amino acid substitution in ParC. The impact of amino acid substitutions in ParE was minimal, and no substitutions in GyrB were identified.

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