scholarly journals Resistance to Cefepime and Cefpirome Due to a 4-Amino-Acid Deletion in the Chromosome-Encoded AmpC β-Lactamase of a Serratia marcescens Clinical Isolate

2004 ◽  
Vol 48 (3) ◽  
pp. 716-720 ◽  
Author(s):  
Hedi Mammeri ◽  
Laurent Poirel ◽  
Pascal Bemer ◽  
Henri Drugeon ◽  
Patrice Nordmann
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract Infection ◽  
Amino Acid ◽  
Serratia Marcescens ◽  
Reference Strain ◽  
Sequencing Analysis ◽  
Amino Acid Deletion ◽  
Synergy Test ◽  
High Level ◽  
Level Resistance

ABSTRACT A multiresistant Serratia marcescens strain, HD, isolated from a patient with a urinary tract infection, was resistant to amino-, carboxy-, and ureidopenicillins, ceftazidime, and cefepime and was susceptible to cefotaxime and ceftriaxone, according to the guidelines of the NCCLS. No synergy was found between expanded-spectrum cephalosporins and clavulanic acid, according to the double-disk synergy test. The bla AmpC gene of the strain was amplified by PCR and cloned into Escherichia coli DH10B, giving rise to high-level resistance to ceftazidime, cefepime, and cefpirome. Sequencing analysis revealed that the bla AmpC gene from S. marcescens HD had a 12-nucleotide deletion compared to the bla AmpC gene from reference strain S. marcescens S3, leading to a 4-amino-acid deletion located in the H-10 helix of the β-lactamase. Kinetic analysis showed that this enzyme significantly hydrolyzed ceftazidime, cefepime, and cefpirome. This work underlined that resistance to the latest expanded-spectrum cephalosporins may be mediated by structurally modified AmpC-type β-lactamases.

scholarly journals Sparfloxacin Resistance in Clinical Isolates ofStreptococcus pneumoniae: Involvement of Multiple Mutations in gyrA and parC Genes

1998 ◽  
Vol 42 (9) ◽  
pp. 2193-2196 ◽  
Author(s):  
Hideki Taba ◽  
Nobuchika Kusano
Keyword(s):  
Streptococcus Pneumoniae ◽  
Amino Acid ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Clinical Isolates ◽  
Amino Acid Substitutions ◽  
Sequencing Analysis ◽  
High Level ◽  
Additional Nucleotide ◽  
Level Resistance

ABSTRACT Antimicrobial susceptibility testing revealed among 150 clinical isolates of Streptococcus pneumoniae 4 pneumococcal isolates with resistance to fluoroquinolones (MIC of ciprofloxacin, ≥32 μg/ml; MIC of sparfloxacin, ≥16 μg/ml). Gene amplification and sequencing analysis of gyrA andparC revealed nucleotide changes leading to amino acid substitutions in both GyrA and ParC of all four fluoroquinolone-resistant isolates. In the case of strains 182 and 674 for which sparfloxacin MICs were 16 and 64 μg/ml, respectively, nucleotide changes were detected at codon 81 in gyrA and codon 79 in parC; these changes led to an Ser→Phe substitution in GyrA and an Ser→Phe substitution in ParC. Strains 354 and 252, for which sparfloxacin MICs were 128 μg/ml, revealed multiple mutations in both gyrA and parC. These strains exhibited nucleotide changes at codon 85 leading to a Glu→Lys substitution in GyrA, in addition to Ser-79→Tyr and Lys-137→Asn substitutions in ParC. Moreover, strain 252 showed additional nucleotide changes at codon 93, which led to a Trp→Arg substitution in GyrA. These results suggest that sparfloxacin resistance could be due to the multiple mutations in GyrA and ParC. However, it is possible that other yet unidentified mutations may also be involved in the high-level resistance to fluoroquinolones in S. pneumoniae.

scholarly journals High-Level Resistance to Ceftazidime Conferred by a Novel Enzyme, CTX-M-32, Derived from CTX-M-1 through a Single Asp240-Gly Substitution

2004 ◽  
Vol 48 (6) ◽  
pp. 2308-2313 ◽  
Author(s):  
Monica Cartelle ◽  
Maria del Mar Tomas ◽  
Francisca Molina ◽  
Rita Moure ◽  
Rosa Villanueva ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Site Directed Mutagenesis ◽  
Clinical Strain ◽  
Directed Mutagenesis ◽  
M Gene ◽  
High Level ◽  
Level Resistance

ABSTRACT A clinical strain of Escherichia coli isolated from pleural liquid with high levels of resistance to cefotaxime, ceftazidime, and aztreonam harbors a novel CTX-M gene (bla CTX-M-32) whose amino acid sequence differs from that of CTX-M-1 by a single Asp240-Gly substitution. Moreover, by site-directed mutagenesis we demonstrated that this replacement is a key event in ceftazidime hydrolysis

scholarly journals Class A Carbapenemase FPH-1 from Francisella philomiragia

2012 ◽  
Vol 56 (6) ◽  
pp. 2852-2857 ◽  
Author(s):  
Marta Toth ◽  
Viktoria Vakulenko ◽  
Nuno T. Antunes ◽  
Hilary Frase ◽  
Sergei B. Vakulenko
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Sequence Identity ◽  
Content Type ◽  
E Coli ◽  
New Class ◽  
Sequence Identity ◽  
Class A ◽  
High Level ◽  
Level Resistance

ABSTRACTFPH-1 is a new class A carbapenemase fromFrancisella philomiragia. It produces high-level resistance to penicillins and the narrow-spectrum cephalosporin cephalothin and hydrolyzes these β-lactam antibiotics with catalytic efficiencies of 106to 107M−1s−1. When expressed inEscherichia coli, the enzyme confers resistance to clavulanic acid, tazobactam, and sulbactam and hasKivalues of 7.5, 4, and 220 μM, respectively, against these inhibitors. FPH-1 increases the MIC of the monobactam aztreonam 256-fold and the MIC of the broad-spectrum cephalosporin ceftazidime 128-fold, while the MIC of cefoxitin remains unchanged. MICs of the carbapenem antibiotics imipenem, meropenem, doripenem, and ertapenem are elevated 8-, 8-, 16-, and 64-fold, respectively, against anE. coliJM83 strain producing the FPH-1 carbapenemase. The catalytic efficiencies of the enzyme against carbapenems are in the range of 104to 105M−1s−1. FPH-1 is 77% identical to the FTU-1 β-lactamase fromFrancisella tularensisand has low amino acid sequence identity with other class A β-lactamases. Together with FTU-1, FPH-1 constitutes a new branch of the prolific and ever-expanding class A β-lactamase tree.

scholarly journals A New SHV-Derived Extended-Spectrum β-Lactamase (SHV-24) That Hydrolyzes Ceftazidime through a Single-Amino-Acid Substitution (D179G) in the Ω-Loop

2000 ◽  
Vol 44 (6) ◽  
pp. 1725-1727 ◽  
Author(s):  
Hiroshi Kurokawa ◽  
Tetsuya Yagi ◽  
Naohiro Shibata ◽  
Keigo Shibayama ◽  
Kazunari Kamachi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Clinical Isolate ◽  
Amino Acid Substitution ◽  
Single Amino Acid Substitution ◽  
Single Amino Acid ◽  
Extended Spectrum ◽  
High Level ◽  
Level Resistance

ABSTRACT A new SHV-derived extended-spectrum β-lactamase (SHV-24) conferring high-level resistance to ceftazidime but not cefotaxime and cefazolin was identified in Japan. This enzyme was encoded by a transferable 150-kb plasmid from an Escherichia coliclinical isolate. The pI and Km for CAZ of this enzyme were 7.5 and 30 μM, respectively. SHV-24 was found to have a D179G substitution in the Ω-loop of the enzyme.

scholarly journals Identification and characterization of a phase-variable element that regulates the autotransporter UpaE in uropathogenicEscherichia coli

2018 ◽  
Author(s):  
E.J. Battaglioli ◽  
K.G.K Goh ◽  
T. S. Atruksang ◽  
K. Schwartz ◽  
M. A. Schembri ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Extracellular Matrix ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Reference Strain ◽  
Invertible Element ◽  
Matrix Proteins ◽  
Phase Variable ◽  
Third Phase ◽  
Strain Cft073

AbstractUropathogenicEscherichia coli(UPEC) are the most common etiological agent of uncomplicated urinary tract infection (UTI). An important mechanism of gene regulation in UPEC is phase variation that involves inversion of a promoter-containing DNA element via enzymatic activity of tyrosine recombinases, resulting in biphasic, ON or OFF expression of target genes. The UPEC reference strain CFT073 has five tyrosine site-specific recombinases that function at two previously characterized promoter inversion systems,fimSandhyxS. Three of the five recombinases are located proximally to their cognate target elements, which is typical of promoter inversion systems. The genes for the other two recombinases, IpuA and IpuB are located distal from these sites. Here, we identified and characterized a third phase variable invertible element in CFT073,ipuSlocated proximal toipuAandipuB. The inversion ofipuSis catalyzed by four of the five CFT073 recombinases. Orientation of the element drives transcription of a two-gene operon containingipuR, a predicted LuxR-type regulator, andupaE, a predicted autotransporter. We show that the predicted autotransporter UpaE is surface-located and facilitates biofilm formation as well as adhesion to extracellular matrix proteins in a K-12 recombinant background. Consistent with this phenotype, theipuSON condition in CFT073 results in defective swimming motility, increased adherence to human kidney epithelial cells, and a positive competitive kidney colonization advantage in experimental mouse UTI infections. Overall, the identification of a third phase-switch in UPEC that is regulated by a shared set of recombinases describes a complex phase-variable virulence network in UPEC.ImportanceUropathogenicEscherichia coli(UPEC) is the most common cause of urinary tract infection (UTI). ON versus OFF phase-switching by inversion of small DNA elements at two chromosome sites in UPEC regulates the expression of important virulence factors, including the type 1 fimbriae adhesion organelle. In this report, we describe a third invertible element,ipuS, in the UPEC reference strain CFT073. The inversion ofipuScontrols the phase variable expression ofupaE, an autotransporter gene that encodes a surface protein involved in adherence to extracellular matrix proteins and colonization of the kidneys in a murine model of UTI.

scholarly journals Characterization of a Novel Plasmid-Mediated Cephalosporinase (CMY-9) and Its Genetic Environment in an Escherichia coli Clinical Isolate

2002 ◽  
Vol 46 (8) ◽  
pp. 2427-2434 ◽  
Author(s):  
Yohei Doi ◽  
Naohiro Shibata ◽  
Keigo Shibayama ◽  
Kazunari Kamachi ◽  
Hiroshi Kurokawa ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Gene Cassette ◽  
Single Amino Acid ◽  
Common Region ◽  
Class 1 Integron ◽  
Class 1 ◽  
The Common ◽  
High Level

ABSTRACT An Escherichia coli strain, HKYM68, which showed resistance to broad-spectrum cephalosporins was isolated from a sputum specimen in Japan. The high-level resistance of the strain to ceftazidime, cefpirome, and moxalactam was carried by a self-transferable plasmid. The β-lactamase gene responsible for the resistance was cloned and sequenced. The deduced amino acid sequence of this gene product, CMY-9, had a single amino acid substitution (E85D), the residue reported to be part of the recognition site for the R1 side chain of β-lactams, compared with the amino acid sequence of CMY-8 and also had 78% identity with the amino acid sequence of CepH, a chromosomal cephalosporinase of Aeromonas hydrophila. A sul1-type class 1 integron containing an aacA1-orfG gene cassette was identified upstream of bla CMY-9 and ended with a truncated 3′ conserved segment. The following 2.1 kb was almost identical to the common region of integrons In6 and In7 and the integron of pSAL-1, except that orf513 encoding a putative transposase was identified instead of orf341 due to addition of a single nucleotide. bla CMY-9 was closely located downstream of the end of the common region. These observations are indicative of the exogenous derivation of bla CMY-9 from some environmental microorganisms such as aeromonads.

scholarly journals Identification and Characterization of a Phase-Variable Element That Regulates the Autotransporter UpaE in UropathogenicEscherichia coli

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
E. J. Battaglioli ◽  
K. G. K. Goh ◽  
T. S. Atruktsang ◽  
K. Schwartz ◽  
M. A. Schembri ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Extracellular Matrix ◽  
Urinary Tract Infection ◽  
Reference Strain ◽  
Invertible Element ◽  
Matrix Proteins ◽  
Phase Variable ◽  
Content Type ◽  
Third Phase ◽  
Strain Cft073

ABSTRACTUropathogenicEscherichia coli(UPEC) is the most common etiologic agent of uncomplicated urinary tract infection (UTI). An important mechanism of gene regulation in UPEC is phase variation that involves inversion of a promoter-containing DNA element via enzymatic activity of tyrosine recombinases, resulting in biphasic, ON or OFF expression of target genes. The UPEC reference strain CFT073 has five tyrosine site-specific recombinases that function at two previously characterized promoter inversion systems,fimSandhyxS. Three of the five recombinases are located proximally to their cognate target elements, which is typical of promoter inversion systems. The genes for the other two recombinases, IpuA and IpuB, are located distal from these sites. Here, we identified and characterized a third phase-variable invertible element in CFT073,ipuS, located proximal toipuAandipuB. The inversion ofipuSis catalyzed by four of the five CFT073 recombinases. Orientation of the element drives transcription of a two-gene operon containingipuR, a predicted LuxR-type regulator, andupaE, a predicted autotransporter. We show that the predicted autotransporter UpaE is surface located and facilitates biofilm formation as well as adhesion to extracellular matrix proteins in a K-12 recombinant background. Consistent with this phenotype, theipuSON condition in CFT073 results in defective swimming motility, increased adherence to human kidney epithelial cells, and a positive competitive kidney colonization advantage in experimental mouse UTIs. Overall, the identification of a third phase switch in UPEC that is regulated by a shared set of recombinases describes a complex phase-variable virulence network in UPEC.IMPORTANCEUropathogenicEscherichia coli(UPEC) is the most common cause of urinary tract infection (UTI). ON versus OFF phase switching by inversion of small DNA elements at two chromosome sites in UPEC regulates the expression of important virulence factors, including the type 1 fimbria adhesion organelle. In this report, we describe a third invertible element,ipuS, in the UPEC reference strain CFT073. The inversion ofipuScontrols the phase-variable expression ofupaE, an autotransporter gene that encodes a surface protein involved in adherence to extracellular matrix proteins and colonization of the kidneys in a murine model of UTI.

scholarly journals Diversity of Substitutions within or Adjacent to Conserved Amino Acid Motifs of Penicillin-Binding Protein 2X in Cephalosporin-Resistant Streptococcus pneumoniaeIsolates

1999 ◽  
Vol 43 (5) ◽  
pp. 1252-1255 ◽  
Author(s):  
Yasuko Asahi ◽  
Yasuo Takeuchi ◽  
Kimiko Ubukata
Keyword(s):  
Streptococcus Pneumoniae ◽  
Amino Acid ◽  
Three Dimensional ◽  
Crystallographic Structure ◽  
Amino Acid Substitutions ◽  
Penicillin Binding Protein ◽  
Amino Acid Motif ◽  
Dna Fragment ◽  
High Level ◽  
Level Resistance

ABSTRACT The sequence of an approximately 1.1-kb DNA fragment of thepbp2x gene, which encodes the transpeptidase domain, was determined for 35 clinical isolates of Streptococcus pneumoniae for which the cefotaxime (CTX) MICs varied. Strains with substitutions within a conserved amino acid motif changing STMK to SAFK and a Leu-to-Val change just before the KSG motif were highly resistant to CTX (MIC, ≧2 μg/ml). Strains with substitutions adjacent to SSN or KSG motifs had low-level resistance. The amino acid substitutions were plotted on the three-dimensional crystallographic structure of the transpeptidase domain of PBP2X. Transformants containing pbp2x from strains with high-level CTX resistance increased the CTX MIC from 0.016 μg/ml to 0.5 to 1.0 μg/ml.

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