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Luísa Peixe

Publications and source records attributed to Luísa Peixe.

16 recordsLinked to original sources
PubMed2006

Emergence and dissemination of Enterobacteriaceae isolates producing CTX-M-1-like enzymes in Spain are associated with IncFII (CTX-M-15) and broad-host-range (CTX-M-1, -3, and -32) plasmids.

The spread of CTX-M-1-like enzymes in Spain is associated with particular plasmids of broad-host-range IncN (blaCTX-M-32, blaCTX-M-1), IncL/M (blaCTX-M-1), and IncA/C2 (blaCTX-M-3) or narrow-host-range IncFII (blaCTX-M-15). The identical genetic surroundings of blaCTX-M-32 and blaCTX-M-1 and their locations on related 40-kb IncN plasmids indicate the in vivo evolution of this element.

Drug Resistance, Bacterial↗
PubMed2006

Characterization of antimicrobial resistance and class 1 and 2 integrons in Salmonella enterica isolates from different sources in Portugal.

OBJECTIVES: The antimicrobial resistance profiles of 1183 Salmonella isolates collected during 2002-2003 from several sources (human, food products and environment) were evaluated. The occurrence, distribution and cassette content of class 1 and 2 integrons among the sulphonamide-resistant population, as well as the role of particular clones to the spread of these genetic elements, were investigated. METHODS: The isolates were examined for susceptibility to antimicrobial agents. The characterization of class 1 and 2 integrons was investigated using PCR, PCR-RFLP (restriction fragment length polymorphism) and sequencing in the sulphonamide-resistant isolates. Conjugation assays and clonality analysis by PFGE were performed. RESULTS: The most common resistance phenotypes were to nalidixic acid, tetracycline, streptomycin, sulfamethoxazole and ampicillin (ranging from 31% to 17%). Resistance to sulphonamides (n=200) was associated with resistance to other antimicrobial agents, with 75% of the isolates carrying one or two class 1 integrons while only 3% simultaneously carried class 1 and 2 integrons. Integrons were observed among at least 11 serotypes (mainly Typhimurium) and in a reduced number of PFGE clones (20). Eight class 1 integron types were found, with the aadA genes (aadA1, aadA2 and aadA5) alone or downstream of a trimethoprim (dfrA1, dfrA12 and dfrA17) or a beta-lactamase resistance gene (blaoxa-30) and the blaPSE-1 gene alone. Most of the class 1 integron types were shared by several clones from the same or different serotypes obtained either from humans or food products of animal origin, especially pork products. However, some Typhimurium-specific integrons were found: aadA2 plus blaPSE-1 and blaoxa-30-aadA1. CONCLUSIONS: Apart from the hypothetical contribution of the conjugative transfer of integrons, the incidence of Salmonella carrying these genetic units seems to rely on the ability of certain clones to spread or persist in particular animal niches. Our data suggest that food-producing animals might be simultaneously considered as a reservoir of clones and integrons carrying antibiotic resistance genes, thus making the food chain, especially pork products, a possible source of multidrug-resistant isolates in humans.

Anti-Bacterial Agents↗
PubMed2006

Beta-nitrostyrene derivatives as potential antibacterial agents: a structure-property-activity relationship study.

A multidisciplinary project was developed, combining the synthesis of a series of beta-nitrostyrene derivatives and the determination of their physicochemical parameters (redox potentials, partition coefficients), to the evaluation of the corresponding antibacterial activity. A complete conformational analysis was also performed, in order to get relevant structural information. Subsequently, a structure-property-activity (SPAR) approach was applied, through linear regression analysis, aiming at obtaining a putative correlation between the physicochemical parameters of the compounds investigated and their antibacterial activity (both against standard strains and clinical isolates). The beta-nitrostyrene compounds displayed a lower activity towards all the tested bacteria relative to the beta-methyl-beta-nitrostyrene analogues. This was observed particularly for the 3-hydroxy-4-methoxy-beta-methyl-beta-nitrostyrene (IVb) against the Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium). The SPAR results revealed the existence of a clear correlation between the redox potentials and the antibacterial activity of the series of beta-nitrostyrene derivatives under study.

Anti-Bacterial Agents↗
PubMed2006

Dissemination and persistence of blaCTX-M-9 are linked to class 1 integrons containing CR1 associated with defective transposon derivatives from Tn402 located in early antibiotic resistance plasmids of IncHI2, IncP1-alpha, and IncFI groups.

This study analyzes the diversity of In60, a class 1 integron bearing CR1 and containing bla(CTX-M-9), and its association with Tn402, Tn21, and classical conjugative plasmids among 45 CTX-M-9-producing clinical strains (41 Escherichia coli strains, 2 Klebsiella pneumoniae strains, 1 Salmonella enterica strain, and 1 Enterobacter cloacae strain). Forty-five patients in a Spanish tertiary care hospital were studied (1996 to 2003). The diversity of In60 and association of In60 with Tn402 or mercury resistance transposons were investigated by overlapping PCR assays and/or hybridization. Plasmid characterization included comparison of restriction fragment length polymorphism patterns and determination of incompatibility group by PCR-based replicon typing, sequencing, and hybridization. CTX-M-9 plasmids belonged to IncHI2 (n = 26), IncP-1alpha (n = 10), IncFI (n = 4), and IncI (n = 1) groups. Genetic platforms containing bla(CTX-M-9) were classified in six types in relation to the In60 backbone and in eight subtypes in relation to Tn402 derivatives. They were associated with Tn21 sequences when located in IncP-1alpha or IncHI2 plasmids. Our study identified bla(CTX-M-9) in a high diversity of CR1-bearing class 1 integrons linked to different Tn402 derivatives, often to Tn21, highlighting the role of recombination events in the evolution of antibiotic resistance plasmids. The presence of bla(CTX-M-9) on broad-host-range IncP-1alpha plasmids might contribute to its dissemination to hosts that were not members of the family Enterobacteriaceae.

DNA Transposable Elements↗
PubMed2006

Multiniche screening reveals the clinically relevant metallo-beta-lactamase VIM-2 in Pseudomonas aeruginosa far from the hospital setting: an ongoing dispersion process?

A screening study of the presence of metallo-beta-lactamases (IMP and VIM types and SPM-1) in isolates from different nonhospital sources was conducted, and it revealed the presence of bla(VIM-2), associated with the In58 class 1 integron, in two unrelated Pseudomonas aeruginosa strains from aquatic habitats. The results suggest that the hospital setting was the possible origin of these bla(VIM-2)-carrying strains.

Animals↗
PubMed2005

Dissemination of sulfonamide resistance genes (sul1, sul2, and sul3) in Portuguese Salmonella enterica strains and relation with integrons.

In 200 sulfonamide-resistant Portuguese Salmonella isolates, 152 sul1, 74 sul2, and 14 sul3 genes were detected. Class 1 integrons were always associated with sul genes, including sul3 alone in some isolates. The sul3 gene has been identified in isolates from different sources and serotypes, which also carried a class 1 integron with aadA and dfrA gene cassettes.

Anti-Bacterial Agents↗
PubMed2005

Integron content of extended-spectrum-beta-lactamase-producing Escherichia coli strains over 12 years in a single hospital in Madrid, Spain.

The contribution of integrons to the dissemination of extended-spectrum beta-lactamases (ESBL) was analyzed on all ESBL-producing Escherichia coli isolates from 1988 to 2000 at Ramon y Cajal Hospital. We studied 133 E. coli pulsed-field gel electrophoresis types: (i) 52 ESBL-producing clinical strains (C-ESBL) (16 TEM, 9 SHV, 21 CTX-M-9, 1 CTX-M-14, and 5 CTX-M-10); (ii) 43 non-ESBL blood clinical strains (C-nESBL); and (iii) 38 non-ESBL fecal isolates from healthy volunteers (V-nESBL). Class 1 integrons were more common among C-ESBL (67%) than among C-nESBL (40%) or V-nESBL (26%) (P < 0.001) due to the high number of strains with bla(CTX-M-9), which is linked to an In6-like class 1 integron. Without this bias, class 1 integron occurrence would be similar in C-ESBL and C-nESBL groups (47% versus 40%). Occurrence of class 2 integrons was similar among clinical and community isolates (13 to 18%). No isolates contained class 3 integrons. The relatively low rate of class 1 integrons within transferable elements carrying bla(TEM) (23%) or bla(SHV) (33%) and the absence of class 2 integrons in all ESBL transconjugants mirror the assembly of translocative pieces containing bla(TEM) or bla(SHV) on local available transferable elements lacking integrons. The low diversity of class 1 integrons (seven types recovered in all groups) might indicate a wide dissemination of specific genetic elements in which they are located. In our environment, the spread of genetic elements encoding ESBL has no major impact on the dispersion of integrons, nor do integrons have a major impact on the spread of ESBL, except when bla(ESBL) genes are within an integron platform such as bla(CTX-M-9).

Cloning, Molecular↗
PubMed2004

Dissemination amongst humans and food products of animal origin of a Salmonella typhimurium clone expressing an integron-borne OXA-30 beta-lactamase.

OBJECTIVES: Characterization of the molecular basis for beta-lactam resistance and evaluation of the clonal relatedness among nine isolates of multidrug-resistant Salmonella typhimurium recovered from seven clinical human samples and two pork end products. METHODS: The isolates were examined for susceptibility to antimicrobial agents. The relationships between resistance genes, class 1 integrons, plasmids and isolates were screened by molecular methods such as polymerase chain reaction and restriction fragment length analysis. RESULTS: A bla(OXA-30) gene, located in a class 1 integron, was detected in all isolates. This integron was present on a conjugative plasmid in all but one isolate. By pulsed-field gel electrophoresis, it was determined that all strains share the same chromosomal type. CONCLUSIONS: This study demonstrates the spread of an OXA-30-producing S. typhimurium in Portugal, suggesting dissemination of a resistant clone through the food chain.

Animals↗
PubMed2003

Incidence of Salmonella from poultry products and their susceptibility to antimicrobial agents.

The incidence of Salmonella in 60 samples of poultry products of national origin available for consumers obtained from two local butcher shops and one canteen of the city of Porto and the susceptibility to antimicrobial agents allowed for human or animal therapy were evaluated. The results show that poultry samples are frequently contaminated with Salmonella (60%), belonging to 10 different serotypes. Salmonella enteritidis and S. hadar were the most prevalent serotypes. In addition, a high number (75%) of the Salmonella isolates was resistant to one or more antimicrobial agents and eight different resistance profiles were recorded. Resistance to nalidixic acid and enrofloxacin was demonstrated for 50% of the isolates and the occurrence of resistant and multiresistant S. enteritidis isolates were less frequent than for S. hadar. This study suggests a high incidence of Salmonella on Portuguese poultry products and shows that they could be a potential vehicle of resistant Salmonella foodborne infections.

Animals↗
PubMed2003

Sfh-I, a subclass B2 metallo-beta-lactamase from a Serratia fonticola environmental isolate.

An environmental isolate of Serratia fonticola resistant to carbapenems was shown to contain a genetic determinant encoding a metallo-beta-lactamase of the subclass B2. The Sfh-I enzyme exhibits some divergence from the previously characterized enzymes of this subclass. This is the first example of a naturally occurring metallo-beta-lactamase in Enterobacteriaceae.

Amino Acid Sequence↗
PubMed2002

Molecular characterization of bla(IMP-5), a new integron-borne metallo-beta-lactamase gene from an Acinetobacter baumannii nosocomial isolate in Portugal.

Acinetobacter baumannii 65FFC, an imipenem-resistant clinical strain, isolated from the urine of a patient at the Coimbra University Hospital, Portugal, in 1998, produced a metallo-beta-lactamase with a calculated pI 9.3. The isolate was highly resistant to penicillins, broad-spectrum cephalosporins, including ceftazidime, ceftriaxone, cefepime, cefpirome, and to aztreonam, but it remained susceptible to ampicillin/sulbactam, aminoglycosides and quinolones. Nucleotide sequence revealed a new allelic variant of other bla(IMP) genes, named bla(IMP-5). IMP-5 beta-lactamase showed a greater homology with IMP-1, IMP-3 and IMP-4 (identified in Southeast Asia), than with IMP-2, found in Italy (93%, 92%, 91% and 87% of amino acid identity, respectively). bla(IMP-5) was the only gene cassette inserted into a class 1 integron, named In76. This is the first IMP-enzyme reported in Portugal and the second in Europe, indicating a wider dissemination in the environment of bla(IMP) alleles.

Acinetobacter Infections↗
PubMed2002

Incidence and susceptibility to antimicrobial agents of Listeria spp. and Listeria monocytogenes isolated from poultry carcasses in Porto, Portugal.

The occurrence of Listeria spp. and Listeria monocytogenes in 63 samples of Portuguese poultry carcasses obtained from two local butcher shops and one canteen in the city of Porto, Portugal, and the susceptibility of these bacteria to antimicrobial agents allowed for use in human or animal therapeutics were evaluated. All poultry samples were contaminated with Listeria spp., and L. monocytogenes was isolated from 41% (26 of 63) of the samples. Other Listeria species, including L. innocua, L. welshimeri, and L. seeligeri, were also isolated from poultry samples. A multiplex polymerase chain reaction method was used for the identification of all of the Listeria isolates; this method showed total conformity with the conventional method of biochemical identification and proved to be more reliable, faster, and less arduous. In addition, high percentages of Listeria spp. (84%) and L. monocytogenes (73%) isolates were found to be resistant to one or more antimicrobial agents of different groups, and 12 different resistance profiles were recorded. The frequency of the resistance of L. monocytogenes isolates to enrofloxacin and clindamycin is notable. The results of this study suggest a high incidence of L. monocytogenes on Portuguese poultry products available for consumers and indicate that poultry could be a potential vehicle of foodborne infections due to strains of L. monocytogenes that are resistant to antimicrobial agents.

Animals↗