Daniela Jones-Dias - Academia.edu (original) (raw)

Papers by Daniela Jones-Dias

Research paper thumbnail of New Class 2 Integron In2-4 Among IncI1-Positive Escherichia coli Isolates Carrying ESBL and PMAβ Genes from Food Animals in Portugal

Foodborne pathogens and disease, Jan 17, 2015

The impact of extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (PMAβ... more The impact of extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (PMAβs) of animal origin constitutes a public health concern. In this study, 179 Escherichia coli from food animals and products were analyzed, among which, 15 cephalosporin-resistant isolates harboring ESBL (CTX-M-1 [n = 8], CTX-M-14 [n = 1], SHV-12 [n = 2]) or PMAβ [CMY-2, n = 5]) were identified in poultry and swine, from different farms of distinct regions of Portugal. The multiple sequence-type IncI1-driven spread of ESBLs and PMAβs, flanked by widely disseminated mobile elements, was guaranteed by ST26/IncI1-harboring blaSHV-12, ST12/IncI1-harboring blaCMY-2, ST3 and ST38/IncI1-harboring blaCTX-M-1, and ST1/IncI1-harboring blaCTX-M-14. An IS10-disrupted In2-4, presenting a new attI2 recombination site, was also detected in a SHV-12/CTX-M-1-harboring isolate. This study highlights the fact that animals may act as persistent sources of ESBL- and PMAβ-harboring plasmids genes that might be...

Research paper thumbnail of Draft Genome Sequence of a Pathogenic O86:H25 Sequence Type 57 Escherichia coli Strain Isolated from Poultry and Carrying 12 Acquired Antibiotic Resistance Genes

Genome announcements, 2015

Escherichia coli is a commensal bacterium that is frequently associated with multidrug-resistant ... more Escherichia coli is a commensal bacterium that is frequently associated with multidrug-resistant zoonotic and foodborne infections. Here, we report the 5.6-Mbp draft genome sequence of an E. coli recovered from poultry, which encodes multiple acquired antibiotic resistance determinants, virulence factors, pathogenicity determinants, and mobile genetic elements.

Research paper thumbnail of Influence of agricultural practice on mobile bla genes: IncI1-bearing CTX-M, SHV, CMY and TEM in Escherichia coli from intensive farming soils

Environmental Microbiology, 2015

Many calls have been made to address antibiotic resistance in an environmental perspective. With ... more Many calls have been made to address antibiotic resistance in an environmental perspective. With this study, we showed the widespread presence of high-level antibiotic resistant isolates on a collection of non-susceptible Gram-negative bacteria (n = 232) recovered from soils. Bacteria were selected using amoxicillin, cefotaxime and imipenem, from sites representing different agricultural practices (extensive, intensive and organic). Striking levels of non-susceptibility were noticed in intensive soils for norfloxacin (74%), streptomycin (50.7%) and tetracycline (46.6%); indeed, the exposure to intensive agricultural practices constituted a risk factor for non-susceptibility to many antibiotics, multidrug resistance and production of extended-spectrum β-lactamases (ESBL). Analyses of non-susceptibility highlighted that environmental and clinical bacteria from the same species might not share the same intrinsic resistance patterns, raising concerns for therapy choices in environment-borne infections. The multiple sequence-type IncI1-driven spread of penicillinases (blaTEM-1 , blaTEM-135 ), ESBL (blaSHV-12 and blaCTX-M-1 ) and plasmid-mediated AmpC β-lactamases (blaCMY-2 ), produced by isolates that share their molecular features with isolates from humans and animals, suggests contamination of agricultural soils. This is also the first appearance of IncI1/ST28-harbouring blaCTX-M-1 , which should be monitored to prevent their establishment as successfully dispersed plasmids. This research may help disclose paths of contamination by mobile antibiotic resistance determinants and the risks for their dissemination.

Research paper thumbnail of Antimicrobial susceptibility and oxymino-β-lactam resistance mechanisms in Salmonella enterica and Escherichia coli isolates from different animal sources

Research in Microbiology, 2015

The impact of extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (PMAβ... more The impact of extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (PMAβs) of animal origin has been a public health concern. In this study, 562 Salmonella enterica and 598 Escherichia coli isolates recovered from different animal species and food products were tested for antimicrobial resistance. Detection of ESBL-, PMAβ-, plasmid-mediated quinolone resistance (PMQR)-encoding genes and integrons was performed in isolates showing non-wild-type phenotypes. Susceptibility profiles of Salmonella spp. isolates differed according to serotype and origin of the isolates. The occurrence of cefotaxime non-wild-type isolates was higher in pets than in other groups. In nine Salmonella isolates, blaCTX-M (n = 4), blaSHV-12 (n = 1), blaTEM-1 (n = 2) and blaCMY-2 (n = 2) were identified. No PMQR-encoding genes were found. In 47 E. coli isolates, blaCTX-M (n = 15), blaSHV-12 (n = 2), blaCMY-2 (n = 6), blaTEM-type (n = 28) and PMQR-encoding genes qnrB (n = 2), qnrS (n = 1) and aac(6')-Ib-cr (n = 6) were detected. To the best of our knowledge, this study is the first to describe the presence of blaCMY-2 (n = 2) and blaSHV-12 (n = 1) genes among S. enterica from broilers in Portugal. This study highlights the fact that animals may act as important reservoirs of isolates carrying ESBL-, PMAβ- and PMQR-encoding genes that might be transferred to humans through direct contact or via the food chain.

Research paper thumbnail of Diversity of extended-spectrum and plasmid-mediated AmpC β-lactamases in Enterobacteriaceae isolates from portuguese health care facilities

Journal of Microbiology, 2014

A group of 124 Enterobacteriaceae isolates resistant to third generation cephalosporins, and coll... more A group of 124 Enterobacteriaceae isolates resistant to third generation cephalosporins, and collected in distinct health care facilities of different Portuguese regions was analysed. The great majority of the isolates were also resistant to fourth generation cephalosporins (83.9%), monobactam (96%), amoxicillin plus clavulanic acid (85.5%), and piperacillin plus tazobactam (66.9%). Overall, 84.7% (105/124) were multidrug resistant. Molecular methods enabled us to identify 86.3% (107/124) extended-spectrum β-lactamases (ESBL) producers, revealing a diversity of class A β-lactamases from different families, like TEM (TEM-1, TEM-10, TEM-24, and TEM-52), SHV (SHV-1, SHV-12, and SHV-28), CTX-M (CTX-M-1, CTX-M-9, CTX-M-14, CTX-M-15, and CTX-M-32), and GES (GES . We have also detected class C enzymes like plasmid-mediated AmpC β-lactamases (PMAβs, DHA-1, and CMY-2) and chromosomal AmpCs in Enterobacter and Citrobacter spp. The PMAβ genetic context mapping suggests association with mobile elements, plasmid importation and the potential emergence of these β-lactamases. The most prevalent β-lactamase detected was CTX-M-15 (66.1%) and in 41.1% of the isolates it was associated with TEM-, OXA-type β-lactamases and Aac(6)'-Ib-cr, which might indicate that the respective genotype has settled in our country. Indeed, CTX-M-15 was distributed amongst distinct clinical settings of several health care facilities (93.5%) from various regions. We provide evidence of a concerning clinical situation that includes vast occurrence of ESBLs, the settling of CTX-M β-lactamases, and the report of plasmidic and chromosomal AmpC in Portugal.

Research paper thumbnail of Role of SHV  -lactamase variants in resistance of clinical Klebsiella pneumoniae strains to  -lactams in an Algerian hospital

Journal of Medical Microbiology, 2011

Three clinical Klebsiella pneumoniae strains, KpARG74, KpARG220 and KpARG185, isolated from a hos... more Three clinical Klebsiella pneumoniae strains, KpARG74, KpARG220 and KpARG185, isolated from a hospital in Algeria, carried the novel b-lactamases SHV-98, SHV-99 and SHV-100, respectively, and co-expressed TEM-1 and either CTX-M-3 or CTX-M-15. In contrast, transformed cells possessing the genes for these novel b-lactamases, i.e. EcDH5a-SHV-98, EcDH5a-SHV-99 and EcDH5a-SHV-100, respectively, carried unique sequence features of bla SHV gene variants, enabling oxyimino-cephalosporin susceptibility and confirming that none of the transformants exhibited extended-spectrum b-lactamase (ESBL) properties. SHV-100 is apparently functional, despite differing from the SHV-1 sequence by duplication of 13 amino acids. The SHV-99 enzyme differed from the parental SHV-1 by the amino acid substitution Asp104AGly, which is an important position in the development of the ESBL phenotype in TEM b-lactamases. This is the first time, to our knowledge, that this mutation has been reported in clinically occurring isolates. Thus, kinetic characterization of the SHV-99 enzyme was performed. The SHV-99 enzyme showed higher affinity (K m of 196 mM), catalytic activity (k cat of 0.5 s "1 ) and catalytic efficiency (k cat /K m of 0.003 mM "1 s "1 ) than SHV-1 b-lactamase against aztreonam. These results showed that the neutral glycine at residue 104 increased the affinity of the enzyme to aztreonam, but was unable to develop the ESBL phenotype in SHV enzymes. As the emergence of new threatening combinations of resistance determinants among nosocomial pathogens is further possible, this study has highlighted the need to reverse the spread of initial mutations.

Research paper thumbnail of First report of CTX-M producing Escherichia coli, including the new ST2526, isolated from beef cattle and sheep in Portugal

Food Control, 2013

ABSTRACT The prevalence of extended-spectrum β-lactamase-containing Escherichia coli isolates was... more ABSTRACT The prevalence of extended-spectrum β-lactamase-containing Escherichia coli isolates was studied in beef cattle and sheep at slaughter in Portugal. CTX-M-producing E. coli isolates were detected in 7% of the 127 fecal samples. The β-lactamase genes detected were as following: CTX-M-32 (n = 4), TEM-1 + CTX-M-1 (n = 3) and CTX-M-1 (n = 2). All CTX-M-containing isolates exhibit a multiresistant phenotype. MLST analysis revealed four different STs under 2 ST complexes (STC10 and STC155) and we detected a novel allelic profile representing a new ST, registered in the database as ST2526. Five of the CTX-M-containing isolates were classified in the B1 phylogroup and 4 isolates in the A phylogroup. Eight isolates harbored at least one of the virulence factors studied. Detection of CTX-M-producers E. coli in beef cattle and sheep raises important questions as they can represent a potential risk factor to public health.

Research paper thumbnail of Vancomycin-resistant enterococci among haemodialysis patients in Portugal: Prevalence and molecular characterization of resistance, virulence and clonality

Enfermedades Infecciosas y Microbiología Clínica, 2014

Vancomycin-resistant enterococci (VRE) among haemodialysis patients has increased rapidly and, to... more Vancomycin-resistant enterococci (VRE) among haemodialysis patients has increased rapidly and, to date, there is no report of this incidence in Portugal. A total of 121 faecal samples were collected from haemodialysis patients, and then tested for VRE. Antimicrobial resistance, virulence and multilocus sequence typing (MLST) were studied. VRE prevalence was 3.3%. Three VRE isolates, Enterococcus faecium, Enterococcus faecalis and Enterococcus raffinosus, were multi-resistant and vanA-positive. E. faecium and E. faecalis belonged to CC17 and CC2, respectively. Haemodialysis patients in Portugal are colonized with virulent, multi-resistant enterococci from high-risk clonal complexes, representing a public health concern.

Research paper thumbnail of High prevalence of ESBL-producing Escherichia coli isolates among hemodialysis patients in Portugal: appearance of ST410 with the blaCTX-M-14 gene

Diagnostic Microbiology and Infectious Disease, 2012

Ten extended-spectrum β-lactamase-producing Escherichia coli isolates were detected among 121 fec... more Ten extended-spectrum β-lactamase-producing Escherichia coli isolates were detected among 121 fecal samples (8.3%) recovered from hemodialysis patients in Portugal. The isolates harbored the bla(CTX-M-15), bla(CTX-M-14a), and/or bla(CTX-M-1) genes. A new sequence type, ST2229, was detected, and this study also reports, for the first time, ST410 CTX-M-14-producing isolates.

Research paper thumbnail of Occurrence of extended-spectrum β-lactamases among chromosomal AmpC-producing Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens in Korea and investigation of screening criteria

Diagnostic Microbiology and Infectious Disease, 2005

We assessed the occurrence and screening criterion for extended-spectrum beta-lactamases (ESBLs) ... more We assessed the occurrence and screening criterion for extended-spectrum beta-lactamases (ESBLs) among AmpC-producing Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens. The 413 isolates (158 E. cloacae, 126 C. freundii, and 129 S. marcescens) isolated from 11 clinical laboratories in Korea were investigated. ESBL production was confirmed by double-disk synergy test and inhibitor-potentiated diffusion test using ceftazidime (CAZ), cefotaxime (CTX), aztreonam (AZT), and cefepime (FEP) with or without clavulanic acid. One hundred seven isolates (25.9%) were as ESBL producers. Of them, resistance was transferred by conjugation in 82 isolates. In transconjugants, structural genes for CTX-M (53.7%), TEM (46.3%), SHV (29.3%) were found. To evaluate the ESBL screening minimum inhibitory concentration (MIC) criteria, MICs for cefuroxime, CAZ, CTX, AZT, and FEP were determined and cutoff value was selected using receiver operator characteristic curve. The FEP MIC > or = 1 microg/mL had the highest sensitivity (95.3%), specificity (82.7%), and positive (65.8%) and negative predictive values (98.3%).

Research paper thumbnail of Assessing the antibiotic susceptibility of freshwater Cyanobacteria spp

Frontiers in Microbiology, 2015

Freshwater is a vehicle for the emergence and dissemination of antibiotic resistance. Cyanobacter... more Freshwater is a vehicle for the emergence and dissemination of antibiotic resistance. Cyanobacteria are ubiquitous in freshwater, where they are exposed to antibiotics and resistant organisms, but their role on water resistome was never evaluated. Data concerning the effects of antibiotics on cyanobacteria, obtained by distinct methodologies, is often contradictory. This emphasizes the importance of developing procedures to understand the trends of antibiotic susceptibility in cyanobacteria. In this study we aimed to evaluate the susceptibility of four cyanobacterial isolates from different genera (Microcystis aeruginosa, Aphanizomenon gracile, Chrisosporum bergii, Planktothix agradhii), and among them nine isolates from the same specie (M. aeruginosa) to distinct antibiotics (amoxicillin, ceftazidime, ceftriaxone, kanamycine, gentamicine, tetracycline, trimethoprim, nalidixic acid, norfloxacin). We used a method adapted from the bacteria standard broth microdilution. Cyanobacteria were exposed to serial dilution of each antibiotic (0.0015-1.6 mg/L) in Z8 medium (20 ± 1°C; 14/10 h L/D cycle; light intensity 16 ± 4 μEm(-2)s(-1)). Cell growth was followed overtime (OD450nm /microscopic examination) and the minimum inhibitory concentrations (MICs) were calculated for each antibiotic/isolate. We found that β-lactams exhibited the lower MICs, aminoglycosides, tetracycline and norfloxacine presented intermediate MICs; none of the isolates were susceptible to trimethoprim and nalidixic acid. The reduced susceptibility of all tested cyanobacteria to some antibiotics suggests that they might be naturally non-susceptible to these compounds, or that they might became non-susceptible due to antibiotic contamination pressure, or to the transfer of genes from resistant bacteria present in the environment.

Research paper thumbnail of New Class 2 Integron In2-4 Among IncI1-Positive Escherichia coli Isolates Carrying ESBL and PMAβ Genes from Food Animals in Portugal

Foodborne pathogens and disease, Jan 17, 2015

The impact of extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (PMAβ... more The impact of extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (PMAβs) of animal origin constitutes a public health concern. In this study, 179 Escherichia coli from food animals and products were analyzed, among which, 15 cephalosporin-resistant isolates harboring ESBL (CTX-M-1 [n = 8], CTX-M-14 [n = 1], SHV-12 [n = 2]) or PMAβ [CMY-2, n = 5]) were identified in poultry and swine, from different farms of distinct regions of Portugal. The multiple sequence-type IncI1-driven spread of ESBLs and PMAβs, flanked by widely disseminated mobile elements, was guaranteed by ST26/IncI1-harboring blaSHV-12, ST12/IncI1-harboring blaCMY-2, ST3 and ST38/IncI1-harboring blaCTX-M-1, and ST1/IncI1-harboring blaCTX-M-14. An IS10-disrupted In2-4, presenting a new attI2 recombination site, was also detected in a SHV-12/CTX-M-1-harboring isolate. This study highlights the fact that animals may act as persistent sources of ESBL- and PMAβ-harboring plasmids genes that might be...

Research paper thumbnail of Draft Genome Sequence of a Pathogenic O86:H25 Sequence Type 57 Escherichia coli Strain Isolated from Poultry and Carrying 12 Acquired Antibiotic Resistance Genes

Genome announcements, 2015

Escherichia coli is a commensal bacterium that is frequently associated with multidrug-resistant ... more Escherichia coli is a commensal bacterium that is frequently associated with multidrug-resistant zoonotic and foodborne infections. Here, we report the 5.6-Mbp draft genome sequence of an E. coli recovered from poultry, which encodes multiple acquired antibiotic resistance determinants, virulence factors, pathogenicity determinants, and mobile genetic elements.

Research paper thumbnail of Influence of agricultural practice on mobile bla genes: IncI1-bearing CTX-M, SHV, CMY and TEM in Escherichia coli from intensive farming soils

Environmental Microbiology, 2015

Many calls have been made to address antibiotic resistance in an environmental perspective. With ... more Many calls have been made to address antibiotic resistance in an environmental perspective. With this study, we showed the widespread presence of high-level antibiotic resistant isolates on a collection of non-susceptible Gram-negative bacteria (n = 232) recovered from soils. Bacteria were selected using amoxicillin, cefotaxime and imipenem, from sites representing different agricultural practices (extensive, intensive and organic). Striking levels of non-susceptibility were noticed in intensive soils for norfloxacin (74%), streptomycin (50.7%) and tetracycline (46.6%); indeed, the exposure to intensive agricultural practices constituted a risk factor for non-susceptibility to many antibiotics, multidrug resistance and production of extended-spectrum β-lactamases (ESBL). Analyses of non-susceptibility highlighted that environmental and clinical bacteria from the same species might not share the same intrinsic resistance patterns, raising concerns for therapy choices in environment-borne infections. The multiple sequence-type IncI1-driven spread of penicillinases (blaTEM-1 , blaTEM-135 ), ESBL (blaSHV-12 and blaCTX-M-1 ) and plasmid-mediated AmpC β-lactamases (blaCMY-2 ), produced by isolates that share their molecular features with isolates from humans and animals, suggests contamination of agricultural soils. This is also the first appearance of IncI1/ST28-harbouring blaCTX-M-1 , which should be monitored to prevent their establishment as successfully dispersed plasmids. This research may help disclose paths of contamination by mobile antibiotic resistance determinants and the risks for their dissemination.

Research paper thumbnail of Antimicrobial susceptibility and oxymino-β-lactam resistance mechanisms in Salmonella enterica and Escherichia coli isolates from different animal sources

Research in Microbiology, 2015

The impact of extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (PMAβ... more The impact of extended-spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC β-lactamases (PMAβs) of animal origin has been a public health concern. In this study, 562 Salmonella enterica and 598 Escherichia coli isolates recovered from different animal species and food products were tested for antimicrobial resistance. Detection of ESBL-, PMAβ-, plasmid-mediated quinolone resistance (PMQR)-encoding genes and integrons was performed in isolates showing non-wild-type phenotypes. Susceptibility profiles of Salmonella spp. isolates differed according to serotype and origin of the isolates. The occurrence of cefotaxime non-wild-type isolates was higher in pets than in other groups. In nine Salmonella isolates, blaCTX-M (n = 4), blaSHV-12 (n = 1), blaTEM-1 (n = 2) and blaCMY-2 (n = 2) were identified. No PMQR-encoding genes were found. In 47 E. coli isolates, blaCTX-M (n = 15), blaSHV-12 (n = 2), blaCMY-2 (n = 6), blaTEM-type (n = 28) and PMQR-encoding genes qnrB (n = 2), qnrS (n = 1) and aac(6')-Ib-cr (n = 6) were detected. To the best of our knowledge, this study is the first to describe the presence of blaCMY-2 (n = 2) and blaSHV-12 (n = 1) genes among S. enterica from broilers in Portugal. This study highlights the fact that animals may act as important reservoirs of isolates carrying ESBL-, PMAβ- and PMQR-encoding genes that might be transferred to humans through direct contact or via the food chain.

Research paper thumbnail of Diversity of extended-spectrum and plasmid-mediated AmpC β-lactamases in Enterobacteriaceae isolates from portuguese health care facilities

Journal of Microbiology, 2014

A group of 124 Enterobacteriaceae isolates resistant to third generation cephalosporins, and coll... more A group of 124 Enterobacteriaceae isolates resistant to third generation cephalosporins, and collected in distinct health care facilities of different Portuguese regions was analysed. The great majority of the isolates were also resistant to fourth generation cephalosporins (83.9%), monobactam (96%), amoxicillin plus clavulanic acid (85.5%), and piperacillin plus tazobactam (66.9%). Overall, 84.7% (105/124) were multidrug resistant. Molecular methods enabled us to identify 86.3% (107/124) extended-spectrum β-lactamases (ESBL) producers, revealing a diversity of class A β-lactamases from different families, like TEM (TEM-1, TEM-10, TEM-24, and TEM-52), SHV (SHV-1, SHV-12, and SHV-28), CTX-M (CTX-M-1, CTX-M-9, CTX-M-14, CTX-M-15, and CTX-M-32), and GES (GES . We have also detected class C enzymes like plasmid-mediated AmpC β-lactamases (PMAβs, DHA-1, and CMY-2) and chromosomal AmpCs in Enterobacter and Citrobacter spp. The PMAβ genetic context mapping suggests association with mobile elements, plasmid importation and the potential emergence of these β-lactamases. The most prevalent β-lactamase detected was CTX-M-15 (66.1%) and in 41.1% of the isolates it was associated with TEM-, OXA-type β-lactamases and Aac(6)'-Ib-cr, which might indicate that the respective genotype has settled in our country. Indeed, CTX-M-15 was distributed amongst distinct clinical settings of several health care facilities (93.5%) from various regions. We provide evidence of a concerning clinical situation that includes vast occurrence of ESBLs, the settling of CTX-M β-lactamases, and the report of plasmidic and chromosomal AmpC in Portugal.

Research paper thumbnail of Role of SHV  -lactamase variants in resistance of clinical Klebsiella pneumoniae strains to  -lactams in an Algerian hospital

Journal of Medical Microbiology, 2011

Three clinical Klebsiella pneumoniae strains, KpARG74, KpARG220 and KpARG185, isolated from a hos... more Three clinical Klebsiella pneumoniae strains, KpARG74, KpARG220 and KpARG185, isolated from a hospital in Algeria, carried the novel b-lactamases SHV-98, SHV-99 and SHV-100, respectively, and co-expressed TEM-1 and either CTX-M-3 or CTX-M-15. In contrast, transformed cells possessing the genes for these novel b-lactamases, i.e. EcDH5a-SHV-98, EcDH5a-SHV-99 and EcDH5a-SHV-100, respectively, carried unique sequence features of bla SHV gene variants, enabling oxyimino-cephalosporin susceptibility and confirming that none of the transformants exhibited extended-spectrum b-lactamase (ESBL) properties. SHV-100 is apparently functional, despite differing from the SHV-1 sequence by duplication of 13 amino acids. The SHV-99 enzyme differed from the parental SHV-1 by the amino acid substitution Asp104AGly, which is an important position in the development of the ESBL phenotype in TEM b-lactamases. This is the first time, to our knowledge, that this mutation has been reported in clinically occurring isolates. Thus, kinetic characterization of the SHV-99 enzyme was performed. The SHV-99 enzyme showed higher affinity (K m of 196 mM), catalytic activity (k cat of 0.5 s "1 ) and catalytic efficiency (k cat /K m of 0.003 mM "1 s "1 ) than SHV-1 b-lactamase against aztreonam. These results showed that the neutral glycine at residue 104 increased the affinity of the enzyme to aztreonam, but was unable to develop the ESBL phenotype in SHV enzymes. As the emergence of new threatening combinations of resistance determinants among nosocomial pathogens is further possible, this study has highlighted the need to reverse the spread of initial mutations.

Research paper thumbnail of First report of CTX-M producing Escherichia coli, including the new ST2526, isolated from beef cattle and sheep in Portugal

Food Control, 2013

ABSTRACT The prevalence of extended-spectrum β-lactamase-containing Escherichia coli isolates was... more ABSTRACT The prevalence of extended-spectrum β-lactamase-containing Escherichia coli isolates was studied in beef cattle and sheep at slaughter in Portugal. CTX-M-producing E. coli isolates were detected in 7% of the 127 fecal samples. The β-lactamase genes detected were as following: CTX-M-32 (n = 4), TEM-1 + CTX-M-1 (n = 3) and CTX-M-1 (n = 2). All CTX-M-containing isolates exhibit a multiresistant phenotype. MLST analysis revealed four different STs under 2 ST complexes (STC10 and STC155) and we detected a novel allelic profile representing a new ST, registered in the database as ST2526. Five of the CTX-M-containing isolates were classified in the B1 phylogroup and 4 isolates in the A phylogroup. Eight isolates harbored at least one of the virulence factors studied. Detection of CTX-M-producers E. coli in beef cattle and sheep raises important questions as they can represent a potential risk factor to public health.

Research paper thumbnail of Vancomycin-resistant enterococci among haemodialysis patients in Portugal: Prevalence and molecular characterization of resistance, virulence and clonality

Enfermedades Infecciosas y Microbiología Clínica, 2014

Vancomycin-resistant enterococci (VRE) among haemodialysis patients has increased rapidly and, to... more Vancomycin-resistant enterococci (VRE) among haemodialysis patients has increased rapidly and, to date, there is no report of this incidence in Portugal. A total of 121 faecal samples were collected from haemodialysis patients, and then tested for VRE. Antimicrobial resistance, virulence and multilocus sequence typing (MLST) were studied. VRE prevalence was 3.3%. Three VRE isolates, Enterococcus faecium, Enterococcus faecalis and Enterococcus raffinosus, were multi-resistant and vanA-positive. E. faecium and E. faecalis belonged to CC17 and CC2, respectively. Haemodialysis patients in Portugal are colonized with virulent, multi-resistant enterococci from high-risk clonal complexes, representing a public health concern.

Research paper thumbnail of High prevalence of ESBL-producing Escherichia coli isolates among hemodialysis patients in Portugal: appearance of ST410 with the blaCTX-M-14 gene

Diagnostic Microbiology and Infectious Disease, 2012

Ten extended-spectrum β-lactamase-producing Escherichia coli isolates were detected among 121 fec... more Ten extended-spectrum β-lactamase-producing Escherichia coli isolates were detected among 121 fecal samples (8.3%) recovered from hemodialysis patients in Portugal. The isolates harbored the bla(CTX-M-15), bla(CTX-M-14a), and/or bla(CTX-M-1) genes. A new sequence type, ST2229, was detected, and this study also reports, for the first time, ST410 CTX-M-14-producing isolates.

Research paper thumbnail of Occurrence of extended-spectrum β-lactamases among chromosomal AmpC-producing Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens in Korea and investigation of screening criteria

Diagnostic Microbiology and Infectious Disease, 2005

We assessed the occurrence and screening criterion for extended-spectrum beta-lactamases (ESBLs) ... more We assessed the occurrence and screening criterion for extended-spectrum beta-lactamases (ESBLs) among AmpC-producing Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens. The 413 isolates (158 E. cloacae, 126 C. freundii, and 129 S. marcescens) isolated from 11 clinical laboratories in Korea were investigated. ESBL production was confirmed by double-disk synergy test and inhibitor-potentiated diffusion test using ceftazidime (CAZ), cefotaxime (CTX), aztreonam (AZT), and cefepime (FEP) with or without clavulanic acid. One hundred seven isolates (25.9%) were as ESBL producers. Of them, resistance was transferred by conjugation in 82 isolates. In transconjugants, structural genes for CTX-M (53.7%), TEM (46.3%), SHV (29.3%) were found. To evaluate the ESBL screening minimum inhibitory concentration (MIC) criteria, MICs for cefuroxime, CAZ, CTX, AZT, and FEP were determined and cutoff value was selected using receiver operator characteristic curve. The FEP MIC > or = 1 microg/mL had the highest sensitivity (95.3%), specificity (82.7%), and positive (65.8%) and negative predictive values (98.3%).

Research paper thumbnail of Assessing the antibiotic susceptibility of freshwater Cyanobacteria spp

Frontiers in Microbiology, 2015

Freshwater is a vehicle for the emergence and dissemination of antibiotic resistance. Cyanobacter... more Freshwater is a vehicle for the emergence and dissemination of antibiotic resistance. Cyanobacteria are ubiquitous in freshwater, where they are exposed to antibiotics and resistant organisms, but their role on water resistome was never evaluated. Data concerning the effects of antibiotics on cyanobacteria, obtained by distinct methodologies, is often contradictory. This emphasizes the importance of developing procedures to understand the trends of antibiotic susceptibility in cyanobacteria. In this study we aimed to evaluate the susceptibility of four cyanobacterial isolates from different genera (Microcystis aeruginosa, Aphanizomenon gracile, Chrisosporum bergii, Planktothix agradhii), and among them nine isolates from the same specie (M. aeruginosa) to distinct antibiotics (amoxicillin, ceftazidime, ceftriaxone, kanamycine, gentamicine, tetracycline, trimethoprim, nalidixic acid, norfloxacin). We used a method adapted from the bacteria standard broth microdilution. Cyanobacteria were exposed to serial dilution of each antibiotic (0.0015-1.6 mg/L) in Z8 medium (20 ± 1°C; 14/10 h L/D cycle; light intensity 16 ± 4 μEm(-2)s(-1)). Cell growth was followed overtime (OD450nm /microscopic examination) and the minimum inhibitory concentrations (MICs) were calculated for each antibiotic/isolate. We found that β-lactams exhibited the lower MICs, aminoglycosides, tetracycline and norfloxacine presented intermediate MICs; none of the isolates were susceptible to trimethoprim and nalidixic acid. The reduced susceptibility of all tested cyanobacteria to some antibiotics suggests that they might be naturally non-susceptible to these compounds, or that they might became non-susceptible due to antibiotic contamination pressure, or to the transfer of genes from resistant bacteria present in the environment.