RESUMEN
Bacterial infections are a global health concern, particularly due to the increasing resistance of bacteria to antibiotics. Multi-drug resistance (MDR) is a considerable challenge, and novel approaches are needed to treat bacterial infections. Photodynamic inactivation (PDI) of microorganisms is increasingly recognized as an effective method to inactivate a broad spectrum of bacteria and overcome resistance mechanisms. This study presents the synthesis of a new cationic 5,15-di-imidazolyl porphyrin derivative and the impact of n-octanol/water partition coefficient (logP) values of this class of photosensitizers on PDI efficacy of Escherichia coli. The derivative with logP = -0.5, IP-H-OH2+, achieved a remarkable 3 log CFU reduction of E. coli at 100 nM with only 1.36 J/cm2 light dose at 415 nm, twice as effective as the second-best porphyrin IP-H-Me2+, of logP = -1.35. We relate the rapid uptake of IP-H-OH2+ by E. coli to improved PDI and the very low uptake of a fluorinated derivative, IP-H-CF32+, logP ≈ 1, to its poor performance. Combination of PDI with cinnamaldehyde, a major component of the cinnamon plant known to alter bacteria cell membranes, offered synergic inactivation of E. coli (7 log CFU reduction), using 50 nM of IP-H-OH2+ and just 1.36 J/cm2 light dose. The success of combining PDI with this natural compound broadens the scope of therapies for MDR infections that do not add drug resistance. In vivo studies on a mouse model of wound infection showed the potential of cationic 5,15-di-imidazolyl porphyrins to treat clinically relevant infected wounds.
Asunto(s)
Acroleína , Antibacterianos , Escherichia coli , Imidazoles , Fármacos Fotosensibilizantes , Porfirinas , Escherichia coli/efectos de los fármacos , Fármacos Fotosensibilizantes/farmacología , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/síntesis química , Porfirinas/farmacología , Porfirinas/química , Antibacterianos/farmacología , Antibacterianos/química , Antibacterianos/síntesis química , Acroleína/análogos & derivados , Acroleína/farmacología , Acroleína/química , Imidazoles/química , Imidazoles/farmacología , Imidazoles/síntesis química , Cationes/química , Cationes/farmacología , Pruebas de Sensibilidad Microbiana , Animales , Ratones , Sinergismo Farmacológico , FotoquimioterapiaRESUMEN
In recent years, multidrug-resistant Acinetobacter baumannii has emerged globally as a major threat to the healthcare system. It is now listed by the World Health Organization as a priority one for the need of new therapeutic agents. A. baumannii has the capacity to develop robust biofilms on biotic and abiotic surfaces. Biofilm development allows these bacteria to resist various environmental stressors, including antibiotics and lack of nutrients or water, which in turn allows the persistence of A. baumannii in the hospital environment and further outbreaks. Investigation into therapeutic alternatives that will act on both biofilm formation and antimicrobial resistance (AMR) is sorely needed. The aim of the present review is to critically discuss the various mechanisms by which AMR and biofilm formation may be co-regulated in A. baumannii in an attempt to shed light on paths towards novel therapeutic opportunities. After discussing the clinical importance of A. baumannii, this critical review highlights biofilm-formation genes that may be associated with the co-regulation of AMR. Particularly worthy of consideration are genes regulating the quorum sensing system AbaI/AbaR, AbOmpA (OmpA protein), Bap (biofilm-associated protein), the two-component regulatory system BfmRS, the PER-1 ß-lactamase, EpsA, and PTK. Finally, this review discusses ongoing experimental therapeutic strategies to fight A. baumannii infections, namely vaccine development, quorum sensing interference, nanoparticles, metal ions, natural products, antimicrobial peptides, and phage therapy. A better understanding of the mechanisms that co-regulate biofilm formation and AMR will help identify new therapeutic targets, as combined approaches may confer synergistic benefits for effective and safer treatments.
Asunto(s)
Acinetobacter baumannii , Antibacterianos , Humanos , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Farmacorresistencia Bacteriana , Biopelículas , Percepción de Quorum , Farmacorresistencia Bacteriana Múltiple/genéticaRESUMEN
Upon consumption, dietary nitrate is reduced to nitrite in the oral cavity and to nitric oxide (â¢NO) in the stomach. Here, â¢NO increases mucosal blood flow, mucus thickness and prevents microbial infections. However, the impact of nitrate on gut microbiota, a pleiotropic organism essential to maintain gastrointestinal and systemic welfare, remains elusive. This study investigates the impact of nitrate on gut microbiota profile and ensued mucosal effects during dysbiosis. Male Wistar rats were randomly distributed in 4 groups and the drinking water was supplemented for 7 days as follows: 1) antibiotic cocktail (neomycin, bacitracin and imipenem), 2) antibiotic cocktail + sodium nitrate, 3) sodium nitrate and 4) regular drinking water. Animals were weighted daily and feces were collected before and after the treatment. The stomach was isolated and the expression of occludin, claudin-5 as well as myeloperoxidase and iNOS was studied. Bacterial DNA was analyzed in fecal samples by PCR-DGGE genetic fingerprinting. Nitrate prevented antibiotic-induced body weight loss (1.9 ± 1.8% vs 8.9⯱â¯1.8%, pâ¯<â¯0.05) and cecamegalia (7.1⯱â¯0.5% vs 5.6⯱â¯0.4%, pâ¯<â¯0.05). Gastric expression of occludin and claudin-5 tended to decrease during dysbiosis but both protein levels were recovered following nitrate consumption (pâ¯<â¯0.05). Similarly, nitrate inhibited the overexpression of myeloperoxidase and iNOS observed under dysbiosis (pâ¯<â¯0.05). Broad spectrum antibiotics significantly decreased microbiota richness and diversity in comparison to controls (pâ¯=â¯0.0016). After 7 days of treatment, whereas antibiotics reduced microbiota richness by 56%, it was observed that nitrate was able to prevent such microbial loss to only 48%, although without statistical differences (pâ¯=â¯0.068). This data suggests that dietary nitrate may be envisaged as a key component of functional foods with beneficial impact on gastric mucosal integrity during antibiotherapy but further studies are mandatory to better ascertain as to whether it modulates intestinal microbiota in terms of taxonomic and functional levels.
Asunto(s)
Claudina-5/metabolismo , Microbioma Gastrointestinal/efectos de los fármacos , Nitratos/uso terapéutico , Óxido Nítrico Sintasa de Tipo II/metabolismo , Ocludina/metabolismo , Peroxidasa/metabolismo , Animales , Antibacterianos , Secuencia de Bases , Ciego/efectos de los fármacos , Disbiosis/inducido químicamente , Heces/microbiología , Mucosa Gástrica/efectos de los fármacos , Inflamación/metabolismo , Masculino , Ratas Wistar , Uniones Estrechas/efectos de los fármacos , Pérdida de Peso/efectos de los fármacosRESUMEN
The small intestine is a significant site of ulceration and bleeding induced by nonsteroidal anti-inflammatory drugs (NSAIDs). The pathogenesis is poorly understood. The present study explored the roles of bile, bacteria, and enterohepatic circulation to NSAID enteropathy, using both a conventional NSAID (naproxen) and a gastrointestinal-safe naproxen derivative (ATB-346), as well as proton pump inhibitors (PPIs). Rats were treated orally with naproxen or equimolar doses of ATB-346 over a 5-day period, with or without PPI administration, and intestinal damage was quantified. The cytotoxicity of bile from the rats was evaluated in vitro. Biliary excretion of naproxen and ATB-346 was determined. The impact of the NSAIDs and of PPIs on the composition of the intestinal microbiota was examined by deep sequencing of 16s rRNA. Naproxen caused significant intestinal damage and inflammation, whereas ATB-346 did not. Naproxen, but not ATB-346, dose dependently increased the cytotoxicity of bile, and it was further increased by PPI coadministration. Whereas biliary excretion of naproxen was significant in naproxen-treated rats, it was greatly reduced in rats treated with ATB-346. The enteric microbiota of naproxen-treated rats was distinct from that in vehicle- or ATB-346-treated rats, and PPI administration caused significant intestinal dysbiosis. The increase in cytotoxicity of bile induced by naproxen and PPIs may contribute significantly to intestinal ulceration and bleeding. Some of these effects may occur secondary to significant changes in the jejunal microbiota induced by both naproxen and PPIs.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Sulfuro de Hidrógeno/farmacología , Enfermedades Intestinales/tratamiento farmacológico , Naproxeno/análogos & derivados , Inhibidores de la Bomba de Protones/farmacología , Animales , Eliminación Hepatobiliar/fisiología , Inflamación/tratamiento farmacológico , Masculino , Naproxeno/farmacología , ARN Ribosómico 16S/genética , Ratas WistarRESUMEN
We have investigated to what extent natural transformation acting on free DNA substrates can facilitate transfer of mobile elements including transposons, integrons and/or gene cassettes between bacterial species. Naturally transformable cells of Acinetobacter baylyi were exposed to DNA from integron-carrying strains of the genera Acinetobacter, Citrobacter, Enterobacter, Escherichia, Pseudomonas, and Salmonella to determine the nature and frequency of transfer. Exposure to the various DNA sources resulted in acquisition of antibiotic resistance traits as well as entire integrons and transposons, over a 24 h exposure period. DNA incorporation was not solely dependent on integrase functions or the genetic relatedness between species. DNA sequence analyses revealed that several mechanisms facilitated stable integration in the recipient genome depending on the nature of the donor DNA; homologous or heterologous recombination and various types of transposition (Tn21-like and IS26-like). Both donor strains and transformed isolates were extensively characterized by antimicrobial susceptibility testing, integron- and cassette-specific PCRs, DNA sequencing, pulsed field gel electrophoreses (PFGE), Southern blot hybridizations, and by re-transformation assays. Two transformant strains were also genome-sequenced. Our data demonstrate that natural transformation facilitates interspecies transfer of genetic elements, suggesting that the transient presence of DNA in the cytoplasm may be sufficient for genomic integration to occur. Our study provides a plausible explanation for why sequence-conserved transposons, IS elements and integrons can be found disseminated among bacterial species. Moreover, natural transformation of integron harboring populations of competent bacteria revealed that interspecies exchange of gene cassettes can be highly efficient, and independent on genetic relatedness between donor and recipient. In conclusion, natural transformation provides a much broader capacity for horizontal acquisitions of genetic elements and hence, resistance traits from divergent species than previously assumed.
Asunto(s)
ADN Bacteriano/metabolismo , Transferencia de Gen Horizontal/fisiología , Bacterias Gramnegativas/fisiología , Integrones/fisiología , Transformación Bacteriana/fisiología , ADN Bacteriano/genéticaRESUMEN
In this work, multicomponent trimethoprim-based pharmaceutical solid systems were developed by mechanochemistry, using coformers from the GRAS list and other active pharmaceutical ingredients. The choice of coformers took into account their potential to increase the aqueous solubility/dissolution rate of TMP or its antibacterial activity. All the binary systems were characterized by thermal analysis, powder X-ray diffraction and infrared spectroscopy, and 3 equimolar systems with FTIR pointing to salts, and 4 eutectic mixtures were identified. The intrinsic dissolution rate of TMP in combination with nicotinic acid (a salt) and with paracetamol (eutectic mixture) were 25% and 5% higher than for pure TMP, respectively. For both Gram-positive and -negative strains, the antibacterial activity of TMP with some of the coformers was improved, since the dosage used was lower than the TMP control. A significant increase in antibacterial activity against E. coli was found for the eutectic mixture with curcumin, with the best results being obtained for the eutectic and equimolar mixtures with ciprofloxacin. Combining trimethoprim with coformers offers an interesting alternative to using trimethoprim alone: multicomponent forms with enhanced TMP dissolution rates were identified, as well as combinations showing enhanced antibacterial activity relatively to the pure drug.
Asunto(s)
Antibacterianos , Escherichia coli , Solubilidad , Trimetoprim , Trimetoprim/química , Trimetoprim/farmacología , Antibacterianos/farmacología , Antibacterianos/química , Escherichia coli/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Acetaminofén/química , Acetaminofén/farmacología , Curcumina/química , Curcumina/farmacología , Difracción de Rayos X/métodos , Química Farmacéutica/métodos , Ciprofloxacina/química , Ciprofloxacina/farmacología , Liberación de FármacosRESUMEN
Various cationic photosensitizers employed in antimicrobial photodynamic therapy (aPDT) have the ability to photoinactivate planktonic bacteria under conditions of low phototoxicity to mammalian cells and without generating antimicrobial resistance (AMR). However, the photoinactivation of biofilms requires orders-of-magnitude higher photosensitizer concentrations, which become toxic to host cells. Remarkably, the bactericidal effect of a dicationic di-imidazolyl chlorin toward planktonic S. aureus and E. coli was observed in this work for concentrations below 400 nM under illumination at 660 nm and below 50 µM for the corresponding biofilms. At the latter concentrations, the chlorin is phototoxic toward human keratinocyte cells. However, in the presence of 50 mM KI, bactericidal concentrations are reduced to less than 50 nM for planktonic bacteria and to less than 1 µM for biofilms. It is shown that the potentiation with KI involves the triiodide anion. This potentiation elicits a bactericidal effect without appreciable cytotoxicity to keratinocytes. It becomes possible to selectively inactivate biofilms with aPDT. An exploratory study treating mice with wounds infected with E. coli expressing GFP with 20 µM chlorin and 120 J cm-2 at 652 nm confirmed the potential of this chlorin to control localized infections.
RESUMEN
Miniature inverted repeat transposable elements (MITEs) have been identified flanking class 1 integrons. We have identified and characterized a 439-bp MITE-like structure in seven Acinetobacter species isolates from Portugal and Brazil. The complete sequence similarity of the elements and flanking regions suggests that MITEs may act as mobilizable vectors for the dissemination of integrons.
Asunto(s)
Infecciones por Acinetobacter/microbiología , Acinetobacter/genética , Elementos Transponibles de ADN , Integrones , Secuencias Invertidas Repetidas , Acinetobacter/aislamiento & purificación , Brasil , ADN Bacteriano/química , ADN Bacteriano/genética , Transferencia de Gen Horizontal , Humanos , Datos de Secuencia Molecular , Portugal , Análisis de Secuencia de ADNRESUMEN
The emergence of new microorganisms with resistance to current antimicrobials is one of the key issues of modern healthcare that must be urgently addressed with the development of new molecules and therapies. Photodynamic inactivation (PDI) in combination with antibiotics has been recently regarded as a promising wide-spectrum therapy for the treatment of localized topical infections. However, further studies are required regarding the selection of the best photosensitizer structures and protocol optimization, in order to maximize the efficiency of this synergic interaction. In this paper, we present results that demonstrate the influence of the structure of cationic imidazolyl-substituted photosensitizers and light on the enhancement of ciprofloxacin (CIP) activity, for the inactivation of Escherichia coli. Structure-activity studies have highlighted the tetra cationic imidazolyl porphyrin IP-H-Me4+ at sub-bactericide concentrations (4-16 nM) as the most promising photosensitizer for combination with sub-inhibitory CIP concentration (<0.25 mg/L). An optimized dual phototherapy protocol using this photosensitizer was translated to in vivo studies in mice wounds infected with E. coli. This synergic combination reduced the amount of photosensitizer and ciprofloxacin required for full E. coli inactivation and, in both in vitro and in vivo studies, the combination therapy was clearly superior to each monotherapy (PDI or ciprofloxacin alone). Overall, these findings highlight the potential of cationic imidazolyl porphyrins in boosting the activity of antibiotics and lowering the probability of resistance development, which is essential for a sustainable long-term treatment of infectious diseases.
Asunto(s)
Infecciones por Escherichia coli , Porfirinas , Animales , Antibacterianos/química , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Cationes/química , Ciprofloxacina/farmacología , Ciprofloxacina/uso terapéutico , Escherichia coli , Infecciones por Escherichia coli/tratamiento farmacológico , Ratones , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/farmacología , Fármacos Fotosensibilizantes/uso terapéutico , Fototerapia , Porfirinas/química , Porfirinas/farmacología , Porfirinas/uso terapéuticoRESUMEN
Klebsiella pneumoniae (Kp) bacteria are an increasing threat to public health and represent one of the most concerning pathogens involved in life-threatening infections and antimicrobial resistance (AMR). To understand the epidemiology of AMR of Kp in Portugal, we analysed whole genome sequencing, susceptibility testing and other meta data on 509 isolates collected nationwide from 16 hospitals and environmental settings between years 1980 and 2019. Predominant sequence types (STs) included ST15 (n = 161, 32%), ST147 (n = 36, 7%), ST14 (n = 26, 5%) or ST13 (n = 26, 5%), while 31% of isolates belonged to STs with fewer than 10 isolates. AMR testing revealed widespread resistance to aminoglycosides, fluoroquinolones, cephalosporins and carbapenems. The most common carbapenemase gene was blaKPC-3. Whilst the distribution of AMR linked plasmids appears uncorrelated with ST, their frequency has changed over time. Before year 2010, the dominant plasmid group was associated with the extended spectrum beta-lactamase gene blaCTX-M-15, but this group appears to have been displaced by another carrying the blaKPC-3 gene. Co-carriage of blaCTX-M and blaKPC-3 was uncommon. Our results from the largest genomics study of Kp in Portugal highlight the active transmission of strains with AMR genes and provide a baseline set of variants for future resistance monitoring and epidemiological studies.
Asunto(s)
Infecciones por Klebsiella , Klebsiella pneumoniae , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Farmacorresistencia Bacteriana/genética , Genómica , Hospitales , Humanos , Infecciones por Klebsiella/tratamiento farmacológico , Infecciones por Klebsiella/epidemiología , Infecciones por Klebsiella/microbiología , Portugal/epidemiologíaRESUMEN
Food contamination due to the presence of microorganisms is a serious problem. New food preservation systems are being studied to kill or inhibit spoilage and pathogenic microorganisms that contaminate food and reduce the shelf life of products. Chitosan films with potential application to food preservation have witnessed great developments during the last years. Chitosan is a cationic polysaccharide with the ability to form films and possess antimicrobial properties. It is water-insoluble but can be dissolved in acidic solutions. In the present work, three different acids (acetic, lactic and citric) were used in chitosan dissolution and both, the resultant solutions and formed films were characterized. It was observed that chitosan water-acetic acid systems show the highest antimicrobial activity due to the highest chitosan charge density, compared to the mixtures with lactic and citric acid. This system showed also the higher solution viscosity compared to the other systems. Chitosan-acetic acid films were also the ones presenting better mechanical properties; this can be attributed to the fact that lactic and citric acids remain in the films, changing their properties, which does not happen with acetic acid. Films produced from chitosan dissolved in water/acetic acid system are resistant, while very fragile but elastic films are formed when lactic acid is used. It was demonstrated that a good selection of the type of acid not only facilitates the dissolution of chitosan but also plays a key role in the properties of the formed solutions and films.
RESUMEN
Horizontal gene transfer events provide the basis for extensive dissemination of antimicrobial resistance traits between bacterial populations. Conjugation is considered to be the most frequent mechanism behind new resistance acquisitions in clinical pathogens but does not fully explain the resistance patterns seen in some bacterial genera. Gene transfer by natural transformation has been described for numerous clinical isolates, including some Acinetobacter species. The main aim of this study was to determine to what extent clinical, resistant Acinetobacter spp. isolates, express competence for natural transformation. Twenty-two clinical Acinetobacter spp. isolates collected over a 16-year time period, from five different geographical separated and/or distinct Portuguese Hospitals were tested for natural transformability. Fourteen isolates, including 11 A. baumannii, 2 A. nosocomialis and 1 Acinetobacter sp., were identified as competent on semisolid media facilitating surface-motility. Competent Acinetobacter isolates were found in all the hospitals tested. Furthermore, osmolarity was shown to influence the uptake of exogenous DNA by competent A. baumannii A118. Our study demonstrates that natural competence is common among clinical isolates of Acinetobacter spp., and hence likely an important trait for resistance acquisition.
Asunto(s)
Infecciones por Acinetobacter/epidemiología , Acinetobacter baumannii/clasificación , Antibacterianos/farmacología , Técnicas de Tipificación Bacteriana , Carbapenémicos/farmacología , Dermatoglifia del ADN , Resistencia betalactámica , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Acinetobacter baumannii/aislamiento & purificación , Análisis por Conglomerados , Humanos , Epidemiología Molecular , Portugal/epidemiología , Análisis de Secuencia de ADNRESUMEN
BACKGROUND: Microbiota dysbiosis and impaired barrier function are among the most prominent features of inflammatory bowel disease. In the gastrointestinal tract, hydrogen sulfide (H(2)S) is an important regulator of mucosal homeostasis. We hypothesized that H(2)S promotes resolution of colonic inflammation through actions on microbiota biofilm and the mucus barrier. METHODS: We used mice genetically deficient for a key enzyme for H(2)S production (cystathionine γ-lyase) and pharmacologically inhibited that enzyme during colitis in wild-type mice. We tested the effects of administering an H(2)S donor (diallyl disulfide) to rodents during hapten-induced colitis. Colonic microbiota biofilm was visualized by fluorescent in situ hybridization, and mucus granules were quantified with periodic acid-alcian blue staining. We exposed human microbiota biofilms and planktonic bacteria to H(2)S donors ex vivo to determine changes in their growth, viability, and biomass. RESULTS: Intestinal microbiota formed linear biofilms in the colon of healthy rodents. During colitis, microbiota biofilms were fragmented and mucus granule production decreased. Endogenous production of H(2)S had beneficial effects on establishment of microbiota biofilms and colonic mucus production. Therapeutic delivery of H(2)S into the colon reduced inflammation, restored the microbiota biofilm, and increased the production of mucus granules. In ex vivo human microbiota, H(2)S not only promoted biofilm formation but also reduced growth of planktonic bacteria. CONCLUSIONS: Our results suggest that H(2)S donors could be used therapeutically during colitis, facilitating correction of microbiota biofilm dysbiosis and mucus layer reconstitution.
Asunto(s)
Biopelículas/efectos de los fármacos , Colitis/prevención & control , Microbioma Gastrointestinal/efectos de los fármacos , Sulfuro de Hidrógeno/uso terapéutico , Mucosa Intestinal/efectos de los fármacos , Moco/metabolismo , Animales , Colitis/inducido químicamente , Colitis/metabolismo , Colitis/microbiología , Sulfato de Dextran/toxicidad , Gasotransmisores/uso terapéutico , Humanos , Hibridación Fluorescente in Situ , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiología , Masculino , Ratones , Ratones Endogámicos C57BL , Moco/efectos de los fármacos , Ratas , Ratas WistarRESUMEN
SIGNIFICANCE: There is a rapidly expanding body of evidence for important roles of hydrogen sulfide in protecting against tissue injury, reducing inflammation, and promoting repair. There is also growing evidence that H2S can be successfully exploited in drug development. RECENT ADVANCES: H2S synthesis and degradation are regulated in circumstances of inflammation and injury so as to promote repair and re-establish homeostasis. Novel H2S-releasing drugs exhibit enhanced anti-inflammatory and pro-restorative effects, while having reduced adverse effects in many tissues. CRITICAL ISSUES: H2S is a pleiotropic mediator, having effects on many elements in the inflammatory cascade and promoting the resolution of inflammation and injury. It also contributes significantly to mucosal defence in the gastrointestinal tract, and in host defence against infection. There is strong evidence that novel, H2S-based therapeutics are safe and effective in animal models, and several are progressing through human trials. FUTURE DIRECTIONS: A better understanding of the physiological and pathophysiological roles of H2S continues to be restrained by the lack of simple, reliable methods for measurement of H2S synthesis, and the paucity of highly selective inhibitors of enzymes that participate in endogenous H2S synthesis. On the other hand, H2S donors show promise as therapeutics for several important indications.
Asunto(s)
Antiinflamatorios/metabolismo , Sulfuro de Hidrógeno/metabolismo , Sulfuro de Hidrógeno/uso terapéutico , Sustancias Protectoras/metabolismo , Heridas y Lesiones/tratamiento farmacológico , Animales , Antiinflamatorios/química , Antiinflamatorios/uso terapéutico , Humanos , Sulfuro de Hidrógeno/química , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Membrana Mucosa/metabolismo , Sustancias Protectoras/química , Sustancias Protectoras/uso terapéutico , Heridas y Lesiones/metabolismoRESUMEN
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.
Asunto(s)
Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/genética , Infección Hospitalaria/microbiología , beta-Lactamasas/genética , Infecciones por Acinetobacter/orina , Secuencia de Aminoácidos , Antibacterianos , Secuencia de Bases , Clonación Molecular , Infección Hospitalaria/orina , Humanos , Imipenem , Integrones/genética , Datos de Secuencia Molecular , Portugal , Resistencia betalactámicaRESUMEN
The objective was to characterize virulence markers and ß-lactam resistance in Klebsiella pneumoniae isolates from renal transplant patients and to evaluate their genetic relatedness. Two main genetic lineages were detected: 1 carried bla(CTX-M-15) not associated to IncFIIA plasmid replicon, which was found on the other lineage not expressing CTX-M-type enzyme. PAI III(536) and PAI II(CFT073) were detected for the first time in K. pneumoniae in 1 clone, while the siderophore kfu was carried by the other, with only PAI IV(536). The molecular data indicate colonization before admission and fuel the discussion on implementation of antibiotherapy before surgery.
Asunto(s)
Trasplante de Riñón , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/clasificación , Klebsiella pneumoniae/genética , Tipificación Molecular , Factores de Virulencia/genética , beta-Lactamasas/genética , Humanos , Klebsiella pneumoniae/aislamiento & purificación , Plásmidos , Receptores de TrasplantesRESUMEN
Integrons are genetic elements first described at the end of the 1980s. Although most integrons were initially described in human clinical isolates, they have now been identified in many non-clinical environments, such as water and soil. Integrons are present in ≈10% of the sequenced bacterial genomes and are frequently linked to mobile genetic elements (MGEs); particularly the class 1 integrons. Genetic linkage to a diverse set of MGEs facilitates horizontal transfer of class 1 integrons within and between bacterial populations and species. The mechanistic aspects limiting transfer of MGEs will therefore limit the transfer of class 1 integrons. However, horizontal movement due to genes provided in trans and homologous recombination can result in class 1 integron dynamics independent of MGEs. A key determinant for continued dissemination of class 1 integrons is the probability that transferred MGEs will be vertically inherited in the recipient bacterial population. Heritability depends both on genetic stability as well as the fitness costs conferred to the host. Here we review the factors known to govern the dissemination of class 1 integrons in bacteria.
RESUMEN
Natural transformation can lead to exchange of DNA between taxonomically diverse bacteria. In the case of chromosomal DNA, homology-based recombination with the recipient genome is usually necessary for heritable stability. In our recent study, we have shown that natural transformation can promote the transfer of transposons, IS elements, and integrons and gene cassettes, largely independent of the genetic relationship between the donor and recipient bacteria. Additional results from our study suggest that natural transformation with species-foreign DNA might result in the uptake of a wide range of DNA fragments; leading to changes in the antimicrobial susceptibility profile and contributing to the generation of antimicrobial resistance in bacteria.