Drug resistance updates : reviews and commentaries in antimicrobial and anticancer chemotherapy, 2018
Antibiotic resistance, and the emergence of pan-resistant clinical isolates, seriously threatens ... more Antibiotic resistance, and the emergence of pan-resistant clinical isolates, seriously threatens our capability to treat bacterial diseases, including potentially deadly hospital-acquired infections. This growing issue certainly requires multiple adequate responses, including the improvement of both diagnosis methods and use of antibacterial agents, and obviously the development of novel antibacterial drugs, especially active against Gram-negative pathogens, which represent an urgent medical need. Considering the clinical relevance of both β-lactam antibiotics and β-lactamase-mediated resistance, the discovery and development of combinations including a β-lactamase inhibitor seems to be particularly attractive, despite being extremely challenging due to the enormous diversity, both structurally and mechanistically, of the potential β-lactamase targets. This review will cover the evolution of currently available β-lactamase inhibitors along with the most recent research leading to ne...
Journal of global antimicrobial resistance, Jan 3, 2017
The aims of this study were to determine the resistance level of a blaCTX-M-37-carrying Enterobac... more The aims of this study were to determine the resistance level of a blaCTX-M-37-carrying Enterobacter cloacae isolate from Mongolia, to analyse kinetic parameters of the purified enzyme and to compare the genetic environment of the gene. Minimum inhibitory concentrations (MICs) were determined using the Clinical and Laboratory Standards Institute (CLSI) agar dilution method. Purified CTX-M-37 enzyme was used to determined kinetic parameters. The genetic environment of the blaCTX-M-37 gene in E. cloacae was compared with a Kluyvera cryocrescens isolate. The E. cloacae isolate showed relatively low-level resistance to cefotaxime (MIC=16mg/L) compared with a CTX-M-3-producing strain (MIC=256mg/L), and CTX-M-37 had a lower kcat/Km value for cefotaxime (2.0μM(-1)s(-1)) compared with CTX-M-3 (3.5μM(-1)s(-1)), possibly due to Asn114Asp substitution. The blaCTX-M-37 gene in the E. cloacae isolate was carried on a conjugative plasmid and was associated with an ISEcp1 element containing the -3...
CPS-1 is a subclass B3 metallo-β-lactamase from a Chryseobacterium piscium isolate collected from... more CPS-1 is a subclass B3 metallo-β-lactamase from a Chryseobacterium piscium isolate collected from soil, showing 68% amino acid identity to the GOB-1 enzyme. CPS-1 was overproduced in Escherichia coli Rosetta (DE3), purified by chromatography, and biochemically characterized. This enzyme exhibits a broad-spectrum substrate profile, including penicillins, cephalosporins, and carbapenems, which overall resembles those of L1, GOB-1, and acquired subclass B3 enzymes AIM-1 and SMB-1.
VIM-39, a VIM-1-like metallo-β-lactamase variant (VIM-1 Thr33Ala His224Leu) was identified in a c... more VIM-39, a VIM-1-like metallo-β-lactamase variant (VIM-1 Thr33Ala His224Leu) was identified in a clinical isolate of Klebsiella pneumoniae belonging to sequence type 147. VIM-39 hydrolyzed ampicillin, cephalothin, and imipenem more efficiently than did VIM-1 and VIM-26 (a VIM-1 variant with the His224Leu substitution) because of higher turnover rates.
The POM-1 metallo-β-lactamase is a subclass B3 resident enzyme produced by Pseudomonas otitidis ,... more The POM-1 metallo-β-lactamase is a subclass B3 resident enzyme produced by Pseudomonas otitidis , a pathogen causing otic infections. The enzyme was overproduced in Escherichia coli BL21(DE3), purified by chromatography, and subjected to structural and functional analysis. The purified POM-1 is a tetrameric enzyme of broad substrate specificity with higher catalytic activities with penicillins and carbapenems than with cephalosporins.
Antibiotic resistance has reached alarming levels in many clinically-relevant human pathogens, an... more Antibiotic resistance has reached alarming levels in many clinically-relevant human pathogens, and there is an increasing clinical need for new antibiotics active on drug-resistant Gram-negative pathogens who rapidly evolve towards pandrug resistance phenotypes. Here, we report on two related classes of guanidinic compounds endowed with antibacterial activity. The two best compounds (9a and 13d) exhibited the most potent antibacterial activity with MIC values ranging 0.12-8μg/ml with most tested pathogens, including both Gram-positive and Gram-negative bacteria. Interestingly, MIC values were not affected (1-8μg/ml) when measured using recent clinical isolates with various antibiotic resistance determinants. The results reported herein identify guazatine derivatives as an interesting starting point for the optimization of a potentially novel class of antibacterial agents.
An outbreak of Pseudomonas aeruginosa showing a multidrug-resistant (MDR) phenotype (including ca... more An outbreak of Pseudomonas aeruginosa showing a multidrug-resistant (MDR) phenotype (including carbapenems, ceftazidime, cefepime, gentamicin, tobramycin, and fluoroquinolones) was observed, during a 5-month period, in a general intensive care unit of a large tertiary care and clinical research hospital in southern Italy. The outbreak involved 15 patients, with a total of 87 isolates, mostly from lower respiratory tract specimens. Analysis of isolates involved in the outbreak revealed production of metallo-β-lactamase (MBL) activity, and genotyping by pulsed-field gel electrophoresis of genomic DNA digested by SpeI revealed clonal relatedness among isolates. Molecular analysis of the MBL determinant showed the presence of a bla IMP-13 gene carried on a gene cassette inserted in a class 1 integron which also contained an aacA4 aminoglycoside resistance cassette encoding an AAC(6′)-Ib enzyme. The bla IMP-13 -containing integron and its genetic environment appeared to be similar to tho...
A microdilution test measuring imipenem MICs in the presence or absence of a mixture of EDTA plus... more A microdilution test measuring imipenem MICs in the presence or absence of a mixture of EDTA plus 1,10-phenanthroline was developed and tested on 190 Pseudomonas aeruginosa isolates, including 18 VIM- and 4 IMP-type metallo-β-lactamase (MBL) producers. The chelator mixture reduced by fourfold or more the imipenem MICs for MBL producers, while a lower effect or no effect was usually observed with MBL nonproducers.
ABSTRACTThe diffusion of metallo-β-lactamases (MBLs) among clinically important human pathogens r... more ABSTRACTThe diffusion of metallo-β-lactamases (MBLs) among clinically important human pathogens represents a therapeutic issue of increasing importance. However, the origin of these resistance determinants is largely unknown, although an important number of proteins belonging to the MBL superfamily have been identified in microbial genomes. In this work, we analyzed the distribution and function of genes encoding MBL-like proteins in the classRhizobiales. Among 12 released complete genomes of members of the classRhizobiales, a total of 57 open reading frames (ORFs) were found to have the MBL conserved motif and identity scores with MBLs ranging from 8 to 40%. On the basis of the best identity scores with known MBLs, four ORFs were cloned intoEscherichia colifor heterologous expression. Among their products, one (blr6230) encoded by theBradyrhizobium japonicumUSDA110 genome, named BJP-1, hydrolyzed β-lactams when expressed inE. coli. BJP-1 enzyme is most closely related to the CAU-1 ...
ABSTRACTEleven environmental samples from different sources were screened for the presence of met... more ABSTRACTEleven environmental samples from different sources were screened for the presence of metallo-β-lactamase-producing bacteria by using a selective enrichment medium containing a carbapenem antibiotic and subsequently testing each isolate for production of EDTA-inhibitable carbapenemase activity. A total of 15 metallo-β-lactamase-producing isolates, including 10Stenotrophomonas maltophiliaisolates, 3Chryseobacteriumspp., oneAeromonas hydrophilaisolate, and oneJanthinobacterium lividumisolate (a species in which production of metallo-β-lactamase activity was not previously reported), were obtained from 8 samples. In theJ. lividumisolate, named JAC1, production of metallo-β-lactamase activity was elicited upon exposure to β-lactams. Screening of a JAC1 genomic library for clones showing a reduced imipenem susceptibility led to the isolation of a metallo-β-lactamase determinant encoding a new member (named THIN-B) of the highly divergent subclass B3 lineage of metallo-β-lactamase...
Acquired metallo-β-lactamases (MBLs) are resistance determinants of increasing clinical importanc... more Acquired metallo-β-lactamases (MBLs) are resistance determinants of increasing clinical importance in Gram-negative bacterial pathogens, which confer a broad-spectrum β-lactam resistance, including carbapenems. Several such enzymes have been described since the 1990s. In the present study, a novel acquired MBL, named FIM-1, was identified and characterized. The bla FIM-1 gene was cloned from a multidrug-resistant Pseudomonas aeruginosa clinical isolate (FI-14/157) cultured from a patient with a vascular graft infection in Florence, Italy. The isolate belonged in the sequence type 235 epidemic clonal lineage. The FIM-1 enzyme is a member of subclass B1 and, among acquired MBLs, exhibited the highest similarity (ca. 40% amino acid identity) with NDM-type enzymes. In P. aeruginosa FI-14/157, the bla FIM-1 gene was apparently inserted into the chromosome and associated with IS CR19 -like elements that were likely involved in the capture and mobilization of this MBL gene. Transfer experi...
Carbapenem resistance mediated by acquired carbapenemase genes has been increasingly reported, pa... more Carbapenem resistance mediated by acquired carbapenemase genes has been increasingly reported, particularly for clinical isolates of Pseudomonas aeruginosa and Acinetobacter spp. Of 1,234 nonduplicate isolates of carbapenem-resistant Pseudomonas spp. and Acinetobacter spp. isolated at a tertiary-care hospital in Seoul, Korea, 211 (17%) were positive for metallo-β-lactamase (MBL). Of these, 204 (96%) had either the bla IMP-1 or bla VIM-2 allele. In addition, seven Acinetobacter baumannii isolates were found to have a novel MBL gene, which was designated bla SIM-1 . The SIM-1 protein has a pI of 7.2, is a new member of subclass B1, and exhibits 64 to 69% identity with the IMP-type MBLs, which are its closest relatives. All SIM-1-producing isolates exhibited relatively low imipenem and meropenem MICs (8 to 16 μg/ml) and had a multidrug resistance phenotype. Expression of the cloned bla SIM-1 gene in Escherichia coli revealed that the encoded enzyme is capable of hydrolyzing a broad arr...
A Pseudomonas putida strain showing broad-spectrum resistance to β-lactams, including expanded-sp... more A Pseudomonas putida strain showing broad-spectrum resistance to β-lactams, including expanded-spectrum cephalosporins and carbapenems, was isolated from a patient with a urinary tract infection at the University Hospital of Varese in northern Italy. The isolate was found to produce metallo-β-lactamase activity and to harbor a 50-kb plasmid, named pVA758, carrying a new bla IMP determinant, named bla IMP-12 . Plasmid pVA758 was not self-transferable by conjugation to either Escherichia coli or Pseudomonas aeruginosa but could be introduced by electroporation and maintained in the latter host, where it conferred resistance or decreased susceptibility to various β-lactams. The IMP-12 enzyme is quite divergent from other IMP variants: its closest relatives are IMP-8 and IMP-2 (89 and 88% sequence identity, respectively), and IMP-1 is 85% identical to IMP-12. The bla IMP-12 determinant is carried on an integron-borne gene cassette whose attC recombination site is related to those presen...
Drug resistance updates : reviews and commentaries in antimicrobial and anticancer chemotherapy, 2018
Antibiotic resistance, and the emergence of pan-resistant clinical isolates, seriously threatens ... more Antibiotic resistance, and the emergence of pan-resistant clinical isolates, seriously threatens our capability to treat bacterial diseases, including potentially deadly hospital-acquired infections. This growing issue certainly requires multiple adequate responses, including the improvement of both diagnosis methods and use of antibacterial agents, and obviously the development of novel antibacterial drugs, especially active against Gram-negative pathogens, which represent an urgent medical need. Considering the clinical relevance of both β-lactam antibiotics and β-lactamase-mediated resistance, the discovery and development of combinations including a β-lactamase inhibitor seems to be particularly attractive, despite being extremely challenging due to the enormous diversity, both structurally and mechanistically, of the potential β-lactamase targets. This review will cover the evolution of currently available β-lactamase inhibitors along with the most recent research leading to ne...
Journal of global antimicrobial resistance, Jan 3, 2017
The aims of this study were to determine the resistance level of a blaCTX-M-37-carrying Enterobac... more The aims of this study were to determine the resistance level of a blaCTX-M-37-carrying Enterobacter cloacae isolate from Mongolia, to analyse kinetic parameters of the purified enzyme and to compare the genetic environment of the gene. Minimum inhibitory concentrations (MICs) were determined using the Clinical and Laboratory Standards Institute (CLSI) agar dilution method. Purified CTX-M-37 enzyme was used to determined kinetic parameters. The genetic environment of the blaCTX-M-37 gene in E. cloacae was compared with a Kluyvera cryocrescens isolate. The E. cloacae isolate showed relatively low-level resistance to cefotaxime (MIC=16mg/L) compared with a CTX-M-3-producing strain (MIC=256mg/L), and CTX-M-37 had a lower kcat/Km value for cefotaxime (2.0μM(-1)s(-1)) compared with CTX-M-3 (3.5μM(-1)s(-1)), possibly due to Asn114Asp substitution. The blaCTX-M-37 gene in the E. cloacae isolate was carried on a conjugative plasmid and was associated with an ISEcp1 element containing the -3...
CPS-1 is a subclass B3 metallo-β-lactamase from a Chryseobacterium piscium isolate collected from... more CPS-1 is a subclass B3 metallo-β-lactamase from a Chryseobacterium piscium isolate collected from soil, showing 68% amino acid identity to the GOB-1 enzyme. CPS-1 was overproduced in Escherichia coli Rosetta (DE3), purified by chromatography, and biochemically characterized. This enzyme exhibits a broad-spectrum substrate profile, including penicillins, cephalosporins, and carbapenems, which overall resembles those of L1, GOB-1, and acquired subclass B3 enzymes AIM-1 and SMB-1.
VIM-39, a VIM-1-like metallo-β-lactamase variant (VIM-1 Thr33Ala His224Leu) was identified in a c... more VIM-39, a VIM-1-like metallo-β-lactamase variant (VIM-1 Thr33Ala His224Leu) was identified in a clinical isolate of Klebsiella pneumoniae belonging to sequence type 147. VIM-39 hydrolyzed ampicillin, cephalothin, and imipenem more efficiently than did VIM-1 and VIM-26 (a VIM-1 variant with the His224Leu substitution) because of higher turnover rates.
The POM-1 metallo-β-lactamase is a subclass B3 resident enzyme produced by Pseudomonas otitidis ,... more The POM-1 metallo-β-lactamase is a subclass B3 resident enzyme produced by Pseudomonas otitidis , a pathogen causing otic infections. The enzyme was overproduced in Escherichia coli BL21(DE3), purified by chromatography, and subjected to structural and functional analysis. The purified POM-1 is a tetrameric enzyme of broad substrate specificity with higher catalytic activities with penicillins and carbapenems than with cephalosporins.
Antibiotic resistance has reached alarming levels in many clinically-relevant human pathogens, an... more Antibiotic resistance has reached alarming levels in many clinically-relevant human pathogens, and there is an increasing clinical need for new antibiotics active on drug-resistant Gram-negative pathogens who rapidly evolve towards pandrug resistance phenotypes. Here, we report on two related classes of guanidinic compounds endowed with antibacterial activity. The two best compounds (9a and 13d) exhibited the most potent antibacterial activity with MIC values ranging 0.12-8μg/ml with most tested pathogens, including both Gram-positive and Gram-negative bacteria. Interestingly, MIC values were not affected (1-8μg/ml) when measured using recent clinical isolates with various antibiotic resistance determinants. The results reported herein identify guazatine derivatives as an interesting starting point for the optimization of a potentially novel class of antibacterial agents.
An outbreak of Pseudomonas aeruginosa showing a multidrug-resistant (MDR) phenotype (including ca... more An outbreak of Pseudomonas aeruginosa showing a multidrug-resistant (MDR) phenotype (including carbapenems, ceftazidime, cefepime, gentamicin, tobramycin, and fluoroquinolones) was observed, during a 5-month period, in a general intensive care unit of a large tertiary care and clinical research hospital in southern Italy. The outbreak involved 15 patients, with a total of 87 isolates, mostly from lower respiratory tract specimens. Analysis of isolates involved in the outbreak revealed production of metallo-β-lactamase (MBL) activity, and genotyping by pulsed-field gel electrophoresis of genomic DNA digested by SpeI revealed clonal relatedness among isolates. Molecular analysis of the MBL determinant showed the presence of a bla IMP-13 gene carried on a gene cassette inserted in a class 1 integron which also contained an aacA4 aminoglycoside resistance cassette encoding an AAC(6′)-Ib enzyme. The bla IMP-13 -containing integron and its genetic environment appeared to be similar to tho...
A microdilution test measuring imipenem MICs in the presence or absence of a mixture of EDTA plus... more A microdilution test measuring imipenem MICs in the presence or absence of a mixture of EDTA plus 1,10-phenanthroline was developed and tested on 190 Pseudomonas aeruginosa isolates, including 18 VIM- and 4 IMP-type metallo-β-lactamase (MBL) producers. The chelator mixture reduced by fourfold or more the imipenem MICs for MBL producers, while a lower effect or no effect was usually observed with MBL nonproducers.
ABSTRACTThe diffusion of metallo-β-lactamases (MBLs) among clinically important human pathogens r... more ABSTRACTThe diffusion of metallo-β-lactamases (MBLs) among clinically important human pathogens represents a therapeutic issue of increasing importance. However, the origin of these resistance determinants is largely unknown, although an important number of proteins belonging to the MBL superfamily have been identified in microbial genomes. In this work, we analyzed the distribution and function of genes encoding MBL-like proteins in the classRhizobiales. Among 12 released complete genomes of members of the classRhizobiales, a total of 57 open reading frames (ORFs) were found to have the MBL conserved motif and identity scores with MBLs ranging from 8 to 40%. On the basis of the best identity scores with known MBLs, four ORFs were cloned intoEscherichia colifor heterologous expression. Among their products, one (blr6230) encoded by theBradyrhizobium japonicumUSDA110 genome, named BJP-1, hydrolyzed β-lactams when expressed inE. coli. BJP-1 enzyme is most closely related to the CAU-1 ...
ABSTRACTEleven environmental samples from different sources were screened for the presence of met... more ABSTRACTEleven environmental samples from different sources were screened for the presence of metallo-β-lactamase-producing bacteria by using a selective enrichment medium containing a carbapenem antibiotic and subsequently testing each isolate for production of EDTA-inhibitable carbapenemase activity. A total of 15 metallo-β-lactamase-producing isolates, including 10Stenotrophomonas maltophiliaisolates, 3Chryseobacteriumspp., oneAeromonas hydrophilaisolate, and oneJanthinobacterium lividumisolate (a species in which production of metallo-β-lactamase activity was not previously reported), were obtained from 8 samples. In theJ. lividumisolate, named JAC1, production of metallo-β-lactamase activity was elicited upon exposure to β-lactams. Screening of a JAC1 genomic library for clones showing a reduced imipenem susceptibility led to the isolation of a metallo-β-lactamase determinant encoding a new member (named THIN-B) of the highly divergent subclass B3 lineage of metallo-β-lactamase...
Acquired metallo-β-lactamases (MBLs) are resistance determinants of increasing clinical importanc... more Acquired metallo-β-lactamases (MBLs) are resistance determinants of increasing clinical importance in Gram-negative bacterial pathogens, which confer a broad-spectrum β-lactam resistance, including carbapenems. Several such enzymes have been described since the 1990s. In the present study, a novel acquired MBL, named FIM-1, was identified and characterized. The bla FIM-1 gene was cloned from a multidrug-resistant Pseudomonas aeruginosa clinical isolate (FI-14/157) cultured from a patient with a vascular graft infection in Florence, Italy. The isolate belonged in the sequence type 235 epidemic clonal lineage. The FIM-1 enzyme is a member of subclass B1 and, among acquired MBLs, exhibited the highest similarity (ca. 40% amino acid identity) with NDM-type enzymes. In P. aeruginosa FI-14/157, the bla FIM-1 gene was apparently inserted into the chromosome and associated with IS CR19 -like elements that were likely involved in the capture and mobilization of this MBL gene. Transfer experi...
Carbapenem resistance mediated by acquired carbapenemase genes has been increasingly reported, pa... more Carbapenem resistance mediated by acquired carbapenemase genes has been increasingly reported, particularly for clinical isolates of Pseudomonas aeruginosa and Acinetobacter spp. Of 1,234 nonduplicate isolates of carbapenem-resistant Pseudomonas spp. and Acinetobacter spp. isolated at a tertiary-care hospital in Seoul, Korea, 211 (17%) were positive for metallo-β-lactamase (MBL). Of these, 204 (96%) had either the bla IMP-1 or bla VIM-2 allele. In addition, seven Acinetobacter baumannii isolates were found to have a novel MBL gene, which was designated bla SIM-1 . The SIM-1 protein has a pI of 7.2, is a new member of subclass B1, and exhibits 64 to 69% identity with the IMP-type MBLs, which are its closest relatives. All SIM-1-producing isolates exhibited relatively low imipenem and meropenem MICs (8 to 16 μg/ml) and had a multidrug resistance phenotype. Expression of the cloned bla SIM-1 gene in Escherichia coli revealed that the encoded enzyme is capable of hydrolyzing a broad arr...
A Pseudomonas putida strain showing broad-spectrum resistance to β-lactams, including expanded-sp... more A Pseudomonas putida strain showing broad-spectrum resistance to β-lactams, including expanded-spectrum cephalosporins and carbapenems, was isolated from a patient with a urinary tract infection at the University Hospital of Varese in northern Italy. The isolate was found to produce metallo-β-lactamase activity and to harbor a 50-kb plasmid, named pVA758, carrying a new bla IMP determinant, named bla IMP-12 . Plasmid pVA758 was not self-transferable by conjugation to either Escherichia coli or Pseudomonas aeruginosa but could be introduced by electroporation and maintained in the latter host, where it conferred resistance or decreased susceptibility to various β-lactams. The IMP-12 enzyme is quite divergent from other IMP variants: its closest relatives are IMP-8 and IMP-2 (89 and 88% sequence identity, respectively), and IMP-1 is 85% identical to IMP-12. The bla IMP-12 determinant is carried on an integron-borne gene cassette whose attC recombination site is related to those presen...
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Papers by Jean-denis Docquier