scholarly journals AmpC β-Lactamase in an Escherichia coli Clinical Isolate Confers Resistance to Expanded-Spectrum Cephalosporins

2004 ◽  
Vol 48 (10) ◽  
pp. 4050-4053 ◽  
Author(s):  
Hedi Mammeri ◽  
Hasan Nazic ◽  
Thierry Naas ◽  
Laurent Poirel ◽  
Sophie Léotard ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Clinical Isolate ◽  
Biochemical Analysis ◽  
Amino Acid Substitutions ◽  
E Coli ◽  
Extended Spectrum

ABSTRACT Cloning, sequencing, and biochemical analysis identified a novel AmpC-type β-lactamase conferring resistance to extended-spectrum cephalosporins in an Escherichia coli clinical isolate. This enzyme, exhibiting 14 amino acid substitutions compared to a reference AmpC cephalosporinase of E. coli, hydrolyzed ceftazidime and cefepime significantly.

scholarly journals TEM-28 from an Escherichia coli clinical isolate is a member of the His-164 family of TEM-1 extended-spectrum beta-lactamases.

1996 ◽  
Vol 40 (1) ◽  
pp. 260-262 ◽  
Author(s):  
P A Bradford ◽  
N V Jacobus ◽  
N Bhachech ◽  
K Bush
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Nucleotide Sequence ◽  
Clinical Isolate ◽  
Amino Acid Substitutions ◽  
Beta Lactamase ◽  
Beta Lactamases ◽  
Extended Spectrum ◽  
Extended Spectrum Beta Lactamases

TEM-28 (pI 6.1), expressed by an Escherichia coli clinical isolate, is a novel beta-lactamase which hydrolyzed ceftazidime, cefotaxime, and aztreonam with rates of 25, 1.1, and 5.6, respectively, relative to that for benzylpenicillin (100). The nucleotide sequence of blaTEM-28 differed from that of blaTEM-1 by two base changes, resulting in amino acid substitutions of Arg-164 to His and Glu-240 to Lys.

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 Ceftazidime-Resistant EnterobacteriaceaeIsolates from Three Polish Hospitals: Identification of Three Novel TEM- and SHV-5-Type Extended-Spectrum β-Lactamases

1998 ◽  
Vol 42 (3) ◽  
pp. 514-520 ◽  
Author(s):  
Marek Gniadkowski ◽  
Ines Schneider ◽  
Renate Jungwirth ◽  
Waleria Hryniewicz ◽  
Adolf Bauernfeind
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Detailed Analysis ◽  
Amino Acid Substitutions ◽  
New Combinations ◽  
Extended Spectrum ◽  
The Family ◽  
Genetic Events ◽  
Esbl Producers

ABSTRACT Twelve ceftazidime-resistant isolates of the familyEnterobacteriaceae (11 Klebsiella pneumoniaeisolates and 1 Escherichia coli isolate) were collected in 1995 from three Polish hospitals located in different cities. All were identified as producers of extended-spectrum β-lactamases (ESBLs). Detailed analysis of their β-lactamase contents revealed that six of them expressed SHV-5-like ESBLs. The remaining six were found to produce three different TEM enzymes, each characterized by a pI value of 6.0 and specified by new combinations of amino acid substitutions. The amino acid substitutions compared to the TEM-1 β-lactamase sequence were Gly238Ser, Glu240Lys, and Thr265Met for TEM-47; Leu21Phe, Gly238Ser, Glu240Lys, and Thr265Met for TEM-48; and Leu21Phe, Gly238Ser, Glu240Lys, Thr265Met, and Ser268Gly for TEM-49. The new TEM β-lactamases, TEM-47, TEM-48, and TEM-49, belong to a subfamily of TEM-2-related enzymes. Genes coding for TEM-47 and TEM-49 could have originated from the TEM-48-encoding sequence by various single genetic events. The new TEM derivatives probably document the already advanced microevolution of ESBLs ongoing in Polish hospitals, in a majority of which no monitoring of ESBL producers was performed before 1996.

scholarly journals TEM-121, a Novel Complex Mutant of TEM-Type β-Lactamase from Enterobacter aerogenes

2004 ◽  
Vol 48 (12) ◽  
pp. 4528-4531 ◽  
Author(s):  
Laurent Poirel ◽  
Hedi Mammeri ◽  
Patrice Nordmann
Keyword(s):  
Amino Acid ◽  
Kinetic Parameters ◽  
Clavulanic Acid ◽  
Clinical Isolate ◽  
Amino Acid Change ◽  
Enterobacter Aerogenes ◽  
Kinetic Properties ◽  
Amino Acid Substitutions ◽  
Extended Spectrum ◽  
Novel Complex

ABSTRACT 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 β-lactamase (TEM-121) differing by five amino acid substitutions from β-lactamase TEM-2 (Glu104Lys, Arg164Ser, Ala237Thr, Glu240Lys, and Arg244Ser) and by only one amino acid change from the extended-spectrum β-lactamase (ESBL) TEM-24 (Arg244Ser), with the last substitution also being identified in the inhibitor-resistant β-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 β-lactamase (CMT-4) combining the kinetic properties of an ESBL and an inhibitor-resistant TEM enzyme.

scholarly journals A complex mutant of TEM-1 beta-lactamase with mutations encountered in both IRT-4 and extended-spectrum TEM-15, produced by an Escherichia coli clinical isolate.

1997 ◽  
Vol 41 (6) ◽  
pp. 1322-1325 ◽  
Author(s):  
D Sirot ◽  
C Recule ◽  
E B Chaibi ◽  
L Bret ◽  
J Croize ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Direct Sequencing ◽  
Hydrolytic Activity ◽  
Beta Lactamase ◽  
E Coli ◽  
Low Level ◽  
Extended Spectrum ◽  
Extended Spectrum Beta Lactamases ◽  
Synergy Test

Escherichia coli GR102 was isolated from feces of a leukemic patient. It expressed different levels of resistance to amoxicillin or ticarcillin plus clavulanate and to the various cephalosporins tested. The double-disk synergy test was weakly positive. Production of a beta-lactamase with a pI of 5.6 was transferred to E. coli HB101 by conjugation. The nucleotide sequence was determined by direct sequencing of the amplification products obtained by PCR performed with TEM gene primers. This enzyme differed from TEM-1 (blaT-1B gene) by four amino acid substitutions: Met-->Leu-69, Glu-->Lys-104, Gly-->Ser-238 and Asn-->Asp-276. The amino acid susbstitutions Leu-69 and Asp-276 are known to be responsible for inhibitor resistance of the IRT-4 mutant, as are Lys-104 and Ser-238 substitutions for hydrolytic activity of the extended-spectrum beta-lactamases TEM-15, TEM-4, and TEM-3. These combined mutations led to a mutant enzyme which conferred a level of resistance to coamoxiclav (MIC, 64 microg/ml) much lower than that conferred by IRT-4 (MIC, 2,048 microg/ml) but higher than that conferred by TEM-15 or TEM-1 (MIC, 16 microg/ml). In addition, the MIC of ceftazidime for E. coli transconjugant GR202 (1 microg/ml) was lower than that for E. coli TEM-15 (16 microg/ml) and higher than that for E. coli IRT-4 or TEM-1 (0.06 microg/ml). The MICs observed for this TEM-type enzyme were related to the kinetic constants Km and k(cat) and the 50% inhibitory concentration, which were intermediate between those observed for IRT-4 and TEM-15. In conclusion, this new type of complex mutant derived from TEM-1 (CMT-1) is able to confer resistance at a very low level to inhibitors and at a low level to extended-spectrum cephalosporins. CMT-1 received the designation TEM-50.

scholarly journals Host Mutations (miaA and rpsL) Reduce Tetracycline Resistance Mediated by Tet(O) and Tet(M)

1998 ◽  
Vol 42 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Diane E. Taylor ◽  
Catharine A. Trieber ◽  
Gudrun Trescher ◽  
Michelle Bekkering
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Tetracycline Resistance ◽  
Acceptor Site ◽  
Amino Acid Substitutions ◽  
Trna Modification ◽  
E Coli ◽  
Translational Accuracy ◽  
Host Genes ◽  
Ribosomal Protection

ABSTRACT The effects of mutations in host genes on tetracycline resistance mediated by the Tet(O) and Tet(M) ribosomal protection proteins, which originated in Campylobacter spp. andStreptococcus spp., respectively, were investigated by using mutants of Salmonella typhimuriumand Escherichia coli. The miaA,miaB, and miaAB double mutants of S. typhimurium specify enzymes for tRNA modification at the adenosine at position 37, adjacent to the anticodon in tRNA. InS. typhimurium, this involves biosynthesis ofN 6-(4-hydroxyisopentenyl)-2-methylthioadenosine (ms2io6A). The miaA mutation reduced the level of tetracycline resistance mediated by both Tet(O) and Tet(M), but the latter showed a greater effect, which was ascribed to the isopentenyl (i6) group or to a combination of the methylthioadenosine (ms2) and i6 groups but not to the ms2 group alone (specified by miaB). In addition, mutations in E. coli rpsL genes, generating both streptomycin-resistant and streptomycin-dependent strains, were also shown to reduce the level of tetracycline resistance mediated by Tet(O) and Tet(M). The single-site amino acid substitutions present in the rpsL mutations were pleiotropic in their effects on tetracycline MICs. These mutants affect translational accuracy and kinetics and suggest that Tet(O) and Tet(M) binding to the ribosome may be reduced or slowed in theE. coli rpsL mutants in which the S12 protein is altered. Data from both the miaA and rpsL mutant studies indicate a possible link between stability of the aminoacyl-tRNA in the ribosomal acceptor site and tetracycline resistance mediated by the ribosomal protection proteins.

Characterization of two plasmid-encoded cefotaximases found in clinical Escherichia coli isolates: CTX-M-65 and a novel enzyme, CTX-M-87

2009 ◽  
Vol 58 (6) ◽  
pp. 811-815 ◽  
Author(s):  
Jun Yin ◽  
Jun Cheng ◽  
Zhen Sun ◽  
Ying Ye ◽  
Yu-Feng Gao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Catalytic Activity ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Hydrolytic Activity ◽  
E Coli ◽  
High Affinity ◽  
Extended Spectrum ◽  
M 14

Three clinical strains of Escherichia coli (p168, p517 and p667) were collected in 2006 from three hospitals in Anhui Province (China). PCR and DNA sequencing revealed that E. coli p168 carried a novel extended-spectrum β-lactamase (ESBL), which was designated CTX-M-87. The extended-spectrum β-lactamase which was carried by E. coli p517 and E. coli p667 was previously named CTX-M-65. The deduced amino acid sequence of CTX-M-87, with pI 9.1, differed from that of CTX-M-14 by the substitutions Ala77→Val and Pro167→Leu. Like CTX-M-14, CTX-M-87 had a more potent hydrolytic activity against cefotaxime than against ceftazidime and had high affinity for cefuroxime and cefotaxime. These data show that mutations at position 167 in CTX-M do not always affect catalytic activity and substrate preference.

scholarly journals NDM-12, a Novel New Delhi Metallo-β-Lactamase Variant from a Carbapenem-Resistant Escherichia coli Clinical Isolate in Nepal

2014 ◽  
Vol 58 (10) ◽  
pp. 6302-6305 ◽  
Author(s):  
Tatsuya Tada ◽  
Basudha Shrestha ◽  
Tohru Miyoshi-Akiyama ◽  
Kayo Shimada ◽  
Hiroshi Ohara ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Clinical Isolate ◽  
Urine Sample ◽  
Enzymatic Activities ◽  
Amino Acid Substitutions ◽  
New Delhi ◽  
Content Type ◽  
Carbapenem Resistant

ABSTRACTA novel New Delhi metallo-β-lactamase variant, NDM-12, was identified in a carbapenem-resistantEscherichia coliclinical isolate obtained from a urine sample from a patient in Nepal. NDM-12 differed from NDM-1 by two amino acid substitutions (M154L and G222D). The enzymatic activities of NDM-12 against β-lactams were similar to those of NDM-1, although NDM-12 showed lowerkcat/Kmratios for all β-lactams tested except doripenem. TheblaNDM-12gene was located in a plasmid of 160 kb.

scholarly journals Emergence of Ertapenem Resistance in an Escherichia coli Clinical Isolate Producing Extended-Spectrum β-Lactamase AmpC

2011 ◽  
Vol 55 (9) ◽  
pp. 4443-4446 ◽  
Author(s):  
Hélène Guillon ◽  
Didier Tande ◽  
Hedi Mammeri
Keyword(s):  
Escherichia Coli ◽  
Bloodstream Infection ◽  
Clinical Isolate ◽  
Biochemical Characterization ◽  
Clinical Isolates ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum ◽  
First Time

ABSTRACTEscherichia coliisolate MEV, responsible for a bloodstream infection, was resistant to penicillins, cephalosporins, and ertapenem. Molecular and biochemical characterization revealed the production of a novel, chromosome-borne, extended-spectrum AmpC (ESAC) β-lactamase with a Ser-282 duplication and increased carbapenemase activity. This study demonstrates for the first time that chromosome-borne ESAC β-lactamases can contribute to the emergence of ertapenem resistance inE. coliclinical isolates.

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