Laura Villa - Academia.edu (original) (raw)
Papers by Laura Villa
European Journal of Obstetrics & Gynecology and Reproductive Biology, 1991
Acta Obstetricia Et Gynecologica Scandinavica, 1990
Journal of The Neurological Sciences, 2006
Mutations in the brain-specific P/Q type Ca2+ channel alpha1 subunit gene, CACNA1A, have been ide... more Mutations in the brain-specific P/Q type Ca2+ channel alpha1 subunit gene, CACNA1A, have been identified in three clinically distinct disorders, spinocerebellar ataxia type 6 (SCA6), episodic ataxia type 2 (EA2), and familial hemiplegic migraine type 1 (FHM1). SCA6 is associated with small expansions of a CAG repeat at the 3' end of the gene, while point mutations are mostly responsible for its two allelic disorders, FHMI and EA2. From the electrophysiological point of view, while FHMI mutations lead to a gain of function [Tottene A, Fellin T, Pagnutti S, Luvisetto S, Striessnig J, Fletcher C, et al. Familial hemiplegic migraine mutations increase Ca2+ influx through single human CaV2.1 channels and decrease maximal CaV2.1 current density in neurons. Proc Natl Acad Sci 99 (20) (2002) 13284-13289.], EA2 mutations usually generate a loss of channel function [Guida S, Trettel F, Pagnutti S, Mantuano E, Tottene A, Veneziano L, et al. Complete loss of P/Q calcium channel activity caused by a CACNA1A missense mutation carried by patients with episodic ataxia type 2. Am J Hum Genet 68 (3) (2001) 759-764, Wappl E, Koschak A, Poteser M, Sinnegger MJ, Walter D, Eberhart A, et al. Functional consequences of P/Q-type Ca2+ channel Cav2.1 missense mutations associated with episodic ataxia type 2 and progressive ataxia. J Biol Chem 277 (9) (2002) 6960-6966.]. In the present study, we describe a child affected by permanent non-fluctuating limb and trunk ataxia with a quite early age of onset. Interestingly, the size of the CACNA1A triplet repeat region in the patient is within the normal range while he carries a novel de novo missense mutation in this gene, p.R1664Q. Although functional data are not available, based on the literature data indicating that severe reductions in P/Q-type channel activity favour episodic and/or progressive ataxic symptoms [Wappl E, Koschak A, Poteser M, Sinnegger MJ, Walter D, Eberhart A, et al. Functional consequences of P/Q-type Ca2+ channel Cav2.1 missense mutations associated with episodic ataxia type 2 and progressive ataxia. J Biol Chem 2002;277(9):6960-6966.], we hypothesize that the functional consequence of the mutation here identified is a partial loss of the Ca channel function. In conclusion, the clinical and molecular findings reported here suggest the opportunity to screen for point mutation in this gene, even patients with a clinical phenotype for some aspects slightly different from the typical picture more commonly associated to SCA6, EA2 or FHM1 diseases.
Journal of Microbiological Methods, 2005
The epidemiological importance of tracing plasmids conferring drug resistance prompted us to deve... more The epidemiological importance of tracing plasmids conferring drug resistance prompted us to develop a PCR method based on replicons (inc/rep PCR) of the major plasmid incompatibility groups among Enterobacteriaceae. Eighteen pairs of primers were designed to perform 5 multiplex-and 3 simplex-PCRs, recognizing FIA, FIB, FIC, HI1, HI2, I1-Ig, L/M, N, P, W, T, A/C, K, B/O, X, Y, F, and FIIA. The specificity of the method was tested on a collection of 61 reference plasmids and on 20 Salmonella enterica strains of different serotypes isolated in Italy. Results indicated that the inc/rep PCR method demonstrates high specificity and sensitivity in detecting replicons on reference plasmids and also revealed the presence of recurrent and common plasmids in epidemiologically unrelated Salmonella isolates of different serotypes. These results suggest that the method is potentially applicable to a large number of strains to trace the diffusion of specific multi-drug resistance plasmids in different environments. D
Antimicrobial Agents and Chemotherapy, 2007
Polymerase chain reaction-based replicon typing represents a novel method to describe the dissemi... more Polymerase chain reaction-based replicon typing represents a novel method to describe the dissemination and follow the evolution of resistance plasmids. We used this approach to study 26 epidemiologically unrelated Enterobacteriaceae and demonstrate the dominance of incompatibility (Inc) A/C or Inc N-related plasmids carrying some emerging resistance determinants to extended-spectrum cephalosporins and carbapenems.
Objectives: Plasmids belonging to incompatibility group I1 (IncI1) are widespread in Enterobacter... more Objectives: Plasmids belonging to incompatibility group I1 (IncI1) are widespread in Enterobacteriaceae and are characterized by the presence of a cluster of genes encoding the type IV pili, contributing to the virulence of Shiga-toxigenic Escherichia coli. Recently, IncI1 plasmids were identified in E. coli and Salmonella strains of animal origin as responsible for the dissemination of b-lactamase genes. Plasmid multilocus sequence typing ( pMLST) was developed to discern naturally occurring IncI1 plasmids in homogeneous groups according to their allele assortment.
From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from pa... more From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from patients with cases of gastroenteritis in southern Italy exhibited resistance to broad-spectrum cephalosporins. Five isolates produced SHV-12, and one isolate encoded a class C -lactamase. The bla SHV-12 gene was located in at least two different self-transferable plasmids, one of which also carried a novel class 1 integron.
Microbial Drug Resistance, 2007
In this study 45 epidemic and sporadic isolates of Acinetobacter baumannii were investigated by a... more In this study 45 epidemic and sporadic isolates of Acinetobacter baumannii were investigated by antimicrobial resistance, integron identifications and genotyping. Isolates were genotyped by random amplified polymorphism (RAPD) DNA and pulsed-field gel electrophoresis (PFGE). Four different RAPD patterns were observed among the isolates of our collection, further discerned in six PFGE types. Two prevalent genotypes were identified, one corresponding to a carbapenem resistant epidemic clone, causing an outbreak at the intensive care unit of a hospital of Rome. Two class 1 integrons, carrying different gene cassette arrays, were identified among the two prevalent genotypes. Nucleotide analysis of the integron-variable regions revealed the presence of the aacA4, orfO, bla(OXA-20), and aacC1, orfX, orfX', aadA1 gene cassette arrays, respectively. All the carbapenem resistant strains analyzed in this study carried the bla (OXA-58) gene located on plasmids.
Journal of Clinical Microbiology, 2002
From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from pa... more From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from patients with cases of gastroenteritis in southern Italy exhibited resistance to broad-spectrum cephalosporins. Five isolates produced SHV-12, and one isolate encoded a class C -lactamase. The bla SHV-12 gene was located in at least two different self-transferable plasmids, one of which also carried a novel class 1 integron.
![Research paper thumbnail of Molecular Characterization of Multidrug-Resistant Strains of Salmonella enterica Serotype Typhimurium and Monophasic Variant ( S. 4,[5],12:i:–) Isolated from Human Infections in Italy](https://attachments.academia-assets.com/48217038/thumbnails/1.jpg)
](Foodborne Pathogens and Disease, 2009
Molecular methods that enable the detection of antimicrobial resistance determinants are critical... more Molecular methods that enable the detection of antimicrobial resistance determinants are critical surveillance tools that are necessary to aid in curbing the spread of antibiotic resistance. In this study, we describe the use of the Antimicrobial Resistance Determinant Microarray (ARDM) that targets 239 unique genes that confer resistance to 12 classes of antimicrobial compounds, quaternary amines and streptothricin for the determination of multidrug resistance (MDR) gene profiles. Fourteen reference MDR strains, which either were genome, sequenced or possessed well characterized drug resistance profiles were used to optimize detection algorithms and threshold criteria to ensure the microarray's effectiveness for unbiased characterization of antimicrobial resistance determinants in MDR strains. The subsequent testing of Acinetobacter baumannii, Escherichia coli and Klebsiella pneumoniae hospital isolates revealed the presence of several antibiotic resistance genes [e.g. belonging to TEM, SHV, OXA and CTX-M classes (and OXA and CTX-M subfamilies) of blactamases] and their assemblages which were confirmed by PCR and DNA sequence analysis. When combined with results from the reference strains, ,25% of the ARDM content was confirmed as effective for representing allelic content from both Gram-positive and -negative species. Taken together, the ARDM identified MDR assemblages containing six to 18 unique resistance genes in each strain tested, demonstrating its utility as a powerful tool for molecular epidemiological investigations of antimicrobial resistance in clinically relevant bacterial pathogens.
Antimicrobial Agents and Chemotherapy, 2005
Three distinct multiresistant loci from enterobacterial plasmids each comprised an integron and a... more Three distinct multiresistant loci from enterobacterial plasmids each comprised an integron and an IS26associated sequence. Sequence comparison suggested a common ancestral structure that derived from an IS26 insertion into the 5 conserved segment of an In4-type integron and evolved through acquisition of gene cassettes and IS26-mediated recruitment of additional resistance genes of diverse origin.
Antimicrobial Agents and Chemotherapy, 2005
Antimicrobial Agents and Chemotherapy, 2008
Antimicrobial Agents and Chemotherapy, 2000
Antimicrobial Agents and Chemotherapy, 2002
Antimicrobial Agents and Chemotherapy, 2006
Microbial Drug Resistance, 2002
Two class 1 integrons, In-t1 and In-t2, were previously identified in IncFI plasmids of Salmonell... more Two class 1 integrons, In-t1 and In-t2, were previously identified in IncFI plasmids of Salmonella enterica serotype Typhimurium. Molecular analysis revealed a close physical link between the two integrons. In-t1 is preceded by the transposase genes of Tn21, whereas In-t2 is located downstream the 3'-conserved segment (3'-CS) of In-t1, in a head-to-tail configuration. In-t1 shows a peculiar sequence downstream the 3'-CS, containing an extended version of the open reading frame known as ORF341 (referred to as ORF341E) and a novel trimethoprim resistance gene, designated dfrA18. Retrospective analysis provided evidence for In-t1 insertion within Tn1935, a Tn21-related transposon identified in IncFI plasmids circulating among epidemic clones of multidrug-resistant S. enterica during the 1970s. Structural comparison between Tn21 derivatives from recent and ancestor IncFI plasmids showed that In-t2 has been conserved by these replicons. In-t1 belongs to a novel family of class 1 integrons containing the ORF341E sequence, and appears to have been acquired by IncFI plasmids after the assembly of Tn1935. In-t1 insertion occurred within the 5'-conserved segment (5'-CS) proximal region of the resident In-t2.
European Journal of Obstetrics & Gynecology and Reproductive Biology, 1991
Acta Obstetricia Et Gynecologica Scandinavica, 1990
Journal of The Neurological Sciences, 2006
Mutations in the brain-specific P/Q type Ca2+ channel alpha1 subunit gene, CACNA1A, have been ide... more Mutations in the brain-specific P/Q type Ca2+ channel alpha1 subunit gene, CACNA1A, have been identified in three clinically distinct disorders, spinocerebellar ataxia type 6 (SCA6), episodic ataxia type 2 (EA2), and familial hemiplegic migraine type 1 (FHM1). SCA6 is associated with small expansions of a CAG repeat at the 3' end of the gene, while point mutations are mostly responsible for its two allelic disorders, FHMI and EA2. From the electrophysiological point of view, while FHMI mutations lead to a gain of function [Tottene A, Fellin T, Pagnutti S, Luvisetto S, Striessnig J, Fletcher C, et al. Familial hemiplegic migraine mutations increase Ca2+ influx through single human CaV2.1 channels and decrease maximal CaV2.1 current density in neurons. Proc Natl Acad Sci 99 (20) (2002) 13284-13289.], EA2 mutations usually generate a loss of channel function [Guida S, Trettel F, Pagnutti S, Mantuano E, Tottene A, Veneziano L, et al. Complete loss of P/Q calcium channel activity caused by a CACNA1A missense mutation carried by patients with episodic ataxia type 2. Am J Hum Genet 68 (3) (2001) 759-764, Wappl E, Koschak A, Poteser M, Sinnegger MJ, Walter D, Eberhart A, et al. Functional consequences of P/Q-type Ca2+ channel Cav2.1 missense mutations associated with episodic ataxia type 2 and progressive ataxia. J Biol Chem 277 (9) (2002) 6960-6966.]. In the present study, we describe a child affected by permanent non-fluctuating limb and trunk ataxia with a quite early age of onset. Interestingly, the size of the CACNA1A triplet repeat region in the patient is within the normal range while he carries a novel de novo missense mutation in this gene, p.R1664Q. Although functional data are not available, based on the literature data indicating that severe reductions in P/Q-type channel activity favour episodic and/or progressive ataxic symptoms [Wappl E, Koschak A, Poteser M, Sinnegger MJ, Walter D, Eberhart A, et al. Functional consequences of P/Q-type Ca2+ channel Cav2.1 missense mutations associated with episodic ataxia type 2 and progressive ataxia. J Biol Chem 2002;277(9):6960-6966.], we hypothesize that the functional consequence of the mutation here identified is a partial loss of the Ca channel function. In conclusion, the clinical and molecular findings reported here suggest the opportunity to screen for point mutation in this gene, even patients with a clinical phenotype for some aspects slightly different from the typical picture more commonly associated to SCA6, EA2 or FHM1 diseases.
Journal of Microbiological Methods, 2005
The epidemiological importance of tracing plasmids conferring drug resistance prompted us to deve... more The epidemiological importance of tracing plasmids conferring drug resistance prompted us to develop a PCR method based on replicons (inc/rep PCR) of the major plasmid incompatibility groups among Enterobacteriaceae. Eighteen pairs of primers were designed to perform 5 multiplex-and 3 simplex-PCRs, recognizing FIA, FIB, FIC, HI1, HI2, I1-Ig, L/M, N, P, W, T, A/C, K, B/O, X, Y, F, and FIIA. The specificity of the method was tested on a collection of 61 reference plasmids and on 20 Salmonella enterica strains of different serotypes isolated in Italy. Results indicated that the inc/rep PCR method demonstrates high specificity and sensitivity in detecting replicons on reference plasmids and also revealed the presence of recurrent and common plasmids in epidemiologically unrelated Salmonella isolates of different serotypes. These results suggest that the method is potentially applicable to a large number of strains to trace the diffusion of specific multi-drug resistance plasmids in different environments. D
Antimicrobial Agents and Chemotherapy, 2007
Polymerase chain reaction-based replicon typing represents a novel method to describe the dissemi... more Polymerase chain reaction-based replicon typing represents a novel method to describe the dissemination and follow the evolution of resistance plasmids. We used this approach to study 26 epidemiologically unrelated Enterobacteriaceae and demonstrate the dominance of incompatibility (Inc) A/C or Inc N-related plasmids carrying some emerging resistance determinants to extended-spectrum cephalosporins and carbapenems.
Objectives: Plasmids belonging to incompatibility group I1 (IncI1) are widespread in Enterobacter... more Objectives: Plasmids belonging to incompatibility group I1 (IncI1) are widespread in Enterobacteriaceae and are characterized by the presence of a cluster of genes encoding the type IV pili, contributing to the virulence of Shiga-toxigenic Escherichia coli. Recently, IncI1 plasmids were identified in E. coli and Salmonella strains of animal origin as responsible for the dissemination of b-lactamase genes. Plasmid multilocus sequence typing ( pMLST) was developed to discern naturally occurring IncI1 plasmids in homogeneous groups according to their allele assortment.
From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from pa... more From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from patients with cases of gastroenteritis in southern Italy exhibited resistance to broad-spectrum cephalosporins. Five isolates produced SHV-12, and one isolate encoded a class C -lactamase. The bla SHV-12 gene was located in at least two different self-transferable plasmids, one of which also carried a novel class 1 integron.
Microbial Drug Resistance, 2007
In this study 45 epidemic and sporadic isolates of Acinetobacter baumannii were investigated by a... more In this study 45 epidemic and sporadic isolates of Acinetobacter baumannii were investigated by antimicrobial resistance, integron identifications and genotyping. Isolates were genotyped by random amplified polymorphism (RAPD) DNA and pulsed-field gel electrophoresis (PFGE). Four different RAPD patterns were observed among the isolates of our collection, further discerned in six PFGE types. Two prevalent genotypes were identified, one corresponding to a carbapenem resistant epidemic clone, causing an outbreak at the intensive care unit of a hospital of Rome. Two class 1 integrons, carrying different gene cassette arrays, were identified among the two prevalent genotypes. Nucleotide analysis of the integron-variable regions revealed the presence of the aacA4, orfO, bla(OXA-20), and aacC1, orfX, orfX', aadA1 gene cassette arrays, respectively. All the carbapenem resistant strains analyzed in this study carried the bla (OXA-58) gene located on plasmids.
Journal of Clinical Microbiology, 2002
From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from pa... more From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from patients with cases of gastroenteritis in southern Italy exhibited resistance to broad-spectrum cephalosporins. Five isolates produced SHV-12, and one isolate encoded a class C -lactamase. The bla SHV-12 gene was located in at least two different self-transferable plasmids, one of which also carried a novel class 1 integron.
Foodborne Pathogens and Disease, 2009
Molecular methods that enable the detection of antimicrobial resistance determinants are critical... more Molecular methods that enable the detection of antimicrobial resistance determinants are critical surveillance tools that are necessary to aid in curbing the spread of antibiotic resistance. In this study, we describe the use of the Antimicrobial Resistance Determinant Microarray (ARDM) that targets 239 unique genes that confer resistance to 12 classes of antimicrobial compounds, quaternary amines and streptothricin for the determination of multidrug resistance (MDR) gene profiles. Fourteen reference MDR strains, which either were genome, sequenced or possessed well characterized drug resistance profiles were used to optimize detection algorithms and threshold criteria to ensure the microarray's effectiveness for unbiased characterization of antimicrobial resistance determinants in MDR strains. The subsequent testing of Acinetobacter baumannii, Escherichia coli and Klebsiella pneumoniae hospital isolates revealed the presence of several antibiotic resistance genes [e.g. belonging to TEM, SHV, OXA and CTX-M classes (and OXA and CTX-M subfamilies) of blactamases] and their assemblages which were confirmed by PCR and DNA sequence analysis. When combined with results from the reference strains, ,25% of the ARDM content was confirmed as effective for representing allelic content from both Gram-positive and -negative species. Taken together, the ARDM identified MDR assemblages containing six to 18 unique resistance genes in each strain tested, demonstrating its utility as a powerful tool for molecular epidemiological investigations of antimicrobial resistance in clinically relevant bacterial pathogens.
Antimicrobial Agents and Chemotherapy, 2005
Three distinct multiresistant loci from enterobacterial plasmids each comprised an integron and a... more Three distinct multiresistant loci from enterobacterial plasmids each comprised an integron and an IS26associated sequence. Sequence comparison suggested a common ancestral structure that derived from an IS26 insertion into the 5 conserved segment of an In4-type integron and evolved through acquisition of gene cassettes and IS26-mediated recruitment of additional resistance genes of diverse origin.
Antimicrobial Agents and Chemotherapy, 2005
Antimicrobial Agents and Chemotherapy, 2008
Antimicrobial Agents and Chemotherapy, 2000
Antimicrobial Agents and Chemotherapy, 2002
Antimicrobial Agents and Chemotherapy, 2006
Microbial Drug Resistance, 2002
Two class 1 integrons, In-t1 and In-t2, were previously identified in IncFI plasmids of Salmonell... more Two class 1 integrons, In-t1 and In-t2, were previously identified in IncFI plasmids of Salmonella enterica serotype Typhimurium. Molecular analysis revealed a close physical link between the two integrons. In-t1 is preceded by the transposase genes of Tn21, whereas In-t2 is located downstream the 3'-conserved segment (3'-CS) of In-t1, in a head-to-tail configuration. In-t1 shows a peculiar sequence downstream the 3'-CS, containing an extended version of the open reading frame known as ORF341 (referred to as ORF341E) and a novel trimethoprim resistance gene, designated dfrA18. Retrospective analysis provided evidence for In-t1 insertion within Tn1935, a Tn21-related transposon identified in IncFI plasmids circulating among epidemic clones of multidrug-resistant S. enterica during the 1970s. Structural comparison between Tn21 derivatives from recent and ancestor IncFI plasmids showed that In-t2 has been conserved by these replicons. In-t1 belongs to a novel family of class 1 integrons containing the ORF341E sequence, and appears to have been acquired by IncFI plasmids after the assembly of Tn1935. In-t1 insertion occurred within the 5'-conserved segment (5'-CS) proximal region of the resident In-t2.