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1.
Nat Commun ; 9(1): 945, 2018 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-29507321

RESUMEN

Marine spatial planning (MSP) seeks to reduce conflicts and environmental impacts, and promote sustainable use of marine ecosystems. Existing MSP approaches have successfully determined how to achieve target levels of ocean area for particular uses while minimizing costs and impacts, but they do not provide a framework that derives analytical solutions in order to co-ordinate siting of multiple uses while balancing the effects of planning on each sector in the system. We develop such a framework for guiding offshore aquaculture (bivalve, finfish, and kelp farming) development in relation to existing sectors and environmental concerns (wild-capture fisheries, viewshed quality, benthic pollution, and disease spread) in California, USA. We identify > 250,000 MSP solutions that generate significant seafood supply and billions of dollars in revenue with minimal impacts (often < 1%) on existing sectors and the environment. We filter solutions to identify candidate locations for high-value, low-impact aquaculture development. Finally, we confirm the expectation of substantial value of our framework over conventional planning focused on maximizing individual objectives.


Asunto(s)
Acuicultura , Conservación de los Recursos Naturales , Ecosistema , Agua de Mar , Geografía
2.
Br J Surg ; 105(2): e131-e141, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-29341151

RESUMEN

BACKGROUND: The pathogenesis of colorectal cancer recurrence after a curative resection remains poorly understood. A yet-to-be accounted for variable is the composition and function of the microbiome adjacent to the tumour and its influence on the margins of resection following surgery. METHODS: PubMed was searched for historical as well as current manuscripts dated between 1970 and 2017 using the following keywords: 'colorectal cancer recurrence', 'microbiome', 'anastomotic leak', 'anastomotic failure' and 'mechanical bowel preparation'. RESULTS: There is a substantial and growing body of literature to demonstrate the various mechanisms by which environmental factors act on the microbiome to alter its composition and function with the net result of adversely affecting oncological outcomes following surgery. Some of these environmental factors include diet, antibiotic use, the methods used to prepare the colon for surgery and the physiological stress of the operation itself. CONCLUSION: Interrogating the intestinal microbiome using next-generation sequencing technology has the potential to influence cancer outcomes following colonic resection.


Asunto(s)
Fuga Anastomótica/microbiología , Neoplasias Colorrectales/cirugía , Microbioma Gastrointestinal , Recurrencia Local de Neoplasia/microbiología , Anastomosis Quirúrgica/efectos adversos , Fuga Anastomótica/etiología , Humanos , Recurrencia Local de Neoplasia/etiología , Cuidados Preoperatorios/efectos adversos , Cuidados Preoperatorios/métodos
3.
Parasite Immunol ; 39(3)2017 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-28075502

RESUMEN

Little is known about cimicosis, the resultant dermal reaction from feeding activity by the common bedbug, Cimex lectularius L. We fed C. lectularius on human study subjects four times over four weeks and measured serum cytokine and antibody levels, and subjects recorded any cimicosis. The average time for subjects to develop cimicosis decreased with each feeding from 8.4, to 2.1, 1.5 and 1.3 days, respectively. There were no significant changes in total IgG, IgG1, IgG2, IgG4 or IgE levels between the first and fourth bedbug feedings, but there was a significant decrease in total IgG3 levels (P<.001). IgG4 was not required for cimicosis. Higher IgG2 and IgG4 levels at study visit 4 were associated with an increased duration of cimicosis (P=.04) and lower pruritis (P=.03), respectively. There were no significant changes in serum TNF-α, IL-1ß, IL-4, IL-5, IL-6, IL-10, IFN-γ and IL-17A levels before and one hour after the C. lectularius feeding. Lower post-C. lectularius feeding IL-6 levels were associated with increased pruritis (P=.001) and the time to maximum pruritis (P=.04), respectively. Higher post-C. lectularius feeding IL-5 levels were associated with a longer duration of pruritis (P=.05).


Asunto(s)
Anticuerpos/sangre , Chinches/inmunología , Citocinas/sangre , Mordeduras y Picaduras de Insectos/inmunología , Animales , Anticuerpos/inmunología , Femenino , Humanos , Inmunoglobulina G/sangre , Mordeduras y Picaduras de Insectos/sangre , Masculino
4.
Conserv Biol ; 30(6): 1182-1191, 2016 12.
Artículo en Inglés | MEDLINE | ID: mdl-26991947

RESUMEN

Marine protected areas (MPAs) are a commonly applied solution to coral reef degradation, yet coral reefs continue to decline worldwide. We argue that expanding the range of MPAs to include degraded reefs (DR-MPA) could help reverse this trend. This approach requires new ecological criteria for MPA design, siting, and management. Rather than focusing solely on preserving healthy reefs, our approach focuses on the potential for biodiversity recovery and renewal of ecosystem services. The new criteria would help identify sites with the highest potential for recovery and the greatest resistance to future threats (e.g., increased temperature and acidification) and sites that contribute to MPA connectivity. The DR-MPA approach is a compliment rather than a substitute for traditional MPA design approaches. We believe that the DR-MPA approach can enhance the natural, or restoration-assisted, recovery of DRs and their ecosystem services; increase total reef area available for protection; promote more resilient and better-connected MPA networks; and improve conditions for human communities dependent on MPA ecosystem services.


Asunto(s)
Conservación de los Recursos Naturales , Arrecifes de Coral , Animales , Antozoos , Biodiversidad , Ecosistema , Humanos
6.
Lett Appl Microbiol ; 60(2): 196-202, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25384850

RESUMEN

Increasingly, molecular methods have become important in identification and confirmation of bacteria at the species level. Rapid molecular methods provide sensitivity and specificity while reducing cost and resources. The primary goal of this study was to develop a real-time PCR assay for identification of Escherichia coli from an agar plate. GadE (gadE) directly regulates the glutamate-dependent acid response system (GDAR) in E. coli and is responsible for survival of at pH 2. Based on gene sequence data, a real-time PCR assay targeting gadE was developed for this purpose. Seventy bacterial isolates recovered from ground beef enrichments and 714 isolates from caecal contents were identified biochemically and tested with the real-time PCR assay developed in this study. The PCR assay and the biochemical identification had 100% agreement on the tested isolates. The gadE real-time PCR assay was demonstrated in this study to be an inexpensive, reliable method for confirming E. coli colonies within 1.5 h from an agar plate, thereby saving on final identification time.


Asunto(s)
Proteínas de Escherichia coli/genética , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Factores de Transcripción/genética , Animales , Bovinos , Ciego/microbiología , Escherichia coli/clasificación , Genes Bacterianos , Carne/microbiología , Sensibilidad y Especificidad
7.
Proc Biol Sci ; 280(1773): 20131684, 2013 Dec 22.
Artículo en Inglés | MEDLINE | ID: mdl-24197407

RESUMEN

Increases in the demand and price for industrial metals, combined with advances in technological capabilities have now made deep-sea mining more feasible and economically viable. In order to balance economic interests with the conservation of abyssal plain ecosystems, it is becoming increasingly important to develop a systematic approach to spatial management and zoning of the deep sea. Here, we describe an expert-driven systematic conservation planning process applied to inform science-based recommendations to the International Seabed Authority for a system of deep-sea marine protected areas (MPAs) to safeguard biodiversity and ecosystem function in an abyssal Pacific region targeted for nodule mining (e.g. the Clarion-Clipperton fracture zone, CCZ). Our use of geospatial analysis and expert opinion in forming the recommendations allowed us to stratify the proposed network by biophysical gradients, maximize the number of biologically unique seamounts within each subregion, and minimize socioeconomic impacts. The resulting proposal for an MPA network (nine replicate 400 × 400 km MPAs) covers 24% (1 440 000 km(2)) of the total CCZ planning region and serves as example of swift and pre-emptive conservation planning across an unprecedented area in the deep sea. As pressure from resource extraction increases in the future, the scientific guiding principles outlined in this research can serve as a basis for collaborative international approaches to ocean management.


Asunto(s)
Conservación de los Recursos Naturales , Minería , Biodiversidad , Océanos y Mares
8.
Appl Environ Microbiol ; 78(6): 1701-7, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22247155

RESUMEN

Escherichia coli isolates were recovered from the National Antimicrobial Resistance Monitoring System retail meat program and examined for antimicrobial susceptibility. Retail meat samples (n = 11,921) from four U.S. states collected during 2002 to 2008, consisting of 2,988 chicken breast, 2,942 ground turkey, 2,991 ground beef, and 3,000 pork chop samples, were analyzed. A total of 8,286 E. coli isolates were recovered. The greatest numbers of samples contaminated with the organism were chicken (83.5%) and turkey (82.0%), followed by beef (68.9%) and pork (44.0%). Resistance was most common to tetracycline (50.3%), followed by streptomycin (34.6%), sulfamethoxazole-sulfisoxazole (31.6%), ampicillin (22.5%), gentamicin (18.6%), kanamycin (8.4%), amoxicillin-clavulanic acid (6.4%), and cefoxitin (5.2%). Less than 5% of the isolates had resistance to trimethoprim, ceftriaxone, ceftiofur, nalidixic acid, chloramphenicol, and ciprofloxacin. All isolates were susceptible to amikacin. Compared to beef and pork isolates, the poultry meat isolates had a greater percentage of resistance to all tested drugs, with the exception of chloramphenicol, to which pork isolates had the most resistance. More than half of the turkey isolates (56%) were resistant to multidrugs (≥3 classes) compared to 38.9% of chicken, 17.3% of pork, and 9.3% of beef isolates. The bla(CMY) gene was present in all ceftriaxone- and ceftiofur-resistant isolates. The cmlA, flo, and catI genes were present in 45%, 43%, and 40% of chloramphenicol-resistant isolates, respectively. Most nalidixic acid-resistant isolates (98.5%) had a gyrA mutation in S83 or D87 or both, whereas only 6.7% had a parC mutation in either S80 or E84. The results showed that E. coli was commonly present in the retail meats, and antimicrobial resistance profiles differed according to the animal origin of the isolates.


Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana , Escherichia coli/efectos de los fármacos , Escherichia coli/aislamiento & purificación , Carne/microbiología , Animales , Proteínas de Escherichia coli/genética , Genes Bacterianos , Pruebas de Sensibilidad Microbiana , Prevalencia , Estados Unidos
9.
Proc Natl Acad Sci U S A ; 107(43): 18266-71, 2010 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-20181570

RESUMEN

Marine reserve theory suggests that where large, productive populations are protected within no-take marine reserves, fished areas outside reserves will benefit through the spillover of larvae produced in the reserves. However, empirical evidence for larval export has been sparse. Here we use a simple idealized coastline model to estimate the expected magnitude and spatial scale of larval export from no-take marine reserves across a range of reserve sizes and larval dispersal scales. Results suggest that, given the magnitude of increased production typically found in marine reserves, benefits from larval export are nearly always large enough to offset increased mortality outside marine reserves due to displaced fishing effort. However, the proportional increase in recruitment at sites outside reserves is typically small, particularly for species with long-distance (on the order of hundreds of kilometers) larval dispersal distances, making it very difficult to detect in field studies. Enhanced recruitment due to export may be detected by sampling several sites at an appropriate range of distances from reserves or at sites downcurrent of reserves in systems with directional dispersal. A review of existing empirical evidence confirms the model's suggestion that detecting export may be difficult without an exceptionally large differential in production, short-distance larval dispersal relative to reserve size, directional dispersal, or a sampling scheme that encompasses a broad range of distances from the reserves.


Asunto(s)
Conservación de los Recursos Naturales , Peces/crecimiento & desarrollo , Biología Marina , Animales , Biomasa , Ecosistema , Explotaciones Pesqueras , Larva/crecimiento & desarrollo , Modelos Biológicos , Dinámica Poblacional
10.
Proc Natl Acad Sci U S A ; 105(26): 8974-9, 2008 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-18577590

RESUMEN

Many nearshore fish and invertebrate populations are overexploited even when apparently coherent management structures are in place. One potential cause of mismanagement may be a poor understanding and accounting of stochasticity, particularly for stock recruitment. Many of the fishes and invertebrates that comprise nearshore fisheries are relatively sedentary as adults but have an obligate larval pelagic stage that is dispersed by ocean currents. Here, we demonstrate that larval connectivity is inherently an intermittent and heterogeneous process on annual time scales. This stochasticity arises from the advection of pelagic larvae by chaotic coastal circulations. This result departs from typical assumptions where larvae simply diffuse from one site to another or where complex connectivity patterns are created by transport within spatially complicated environments. We derive a statistical model for the expected variability in larval settlement patterns and demonstrate how larval connectivity varies as a function of different biological and physical processes. The stochastic nature of larval connectivity creates an unavoidable uncertainty in the assessment of fish recruitment and the resulting forecasts of sustainable yields.


Asunto(s)
Peces/crecimiento & desarrollo , Invertebrados/crecimiento & desarrollo , Animales , Larva/crecimiento & desarrollo , Larva/fisiología , Estadios del Ciclo de Vida , Modelos Biológicos , Océanos y Mares , Procesos Estocásticos , Factores de Tiempo
11.
Mar Pollut Bull ; 56(3): 430-8, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18155069

RESUMEN

Coastal marine reserves in general, and coral reef reserves in particular, are typically composed of scattered patches separated by uninhabited areas. Due to the sessile mode of life of adult corals, larval connectivity is often the only agent of gene flow between reef localities. In this study we examined the connectivity between populations of the common scleratinian coral Stylophora pistillata at the northern tip of the Gulf of Aqaba (Red Sea), using the rDNA ITS (internal transcribed spacer) as a molecular marker. Sequence comparisons among recruits indicated very similar, equally-diverse, assemblages of recruits in both the northern (highly affected by anthropogenic disturbances) and southern (less affected) study sites, implying a high larval connectivity or common sources of larval supply. By contrast, sequence diversity observed among adults declined sharply from southern to northern sites, accompanied by genetic differentiation of the respective populations. Based on Fu's Fs-test of selective neutrality, it may be suggested that various post-settlement selective regimes, presumably more intense in the northern sites, provide a reasonable explanation for the observed patterns of genetic diversity. The suggested hypothesis is supported by the sharper decline in sequence diversity found between recruits and adults in the northern sites. This study exemplifies the necessity to consider local selective factors, in addition to larval connectivity, when managing marine reserves.


Asunto(s)
Antozoos/genética , Ecosistema , Monitoreo del Ambiente , Estructuras Genéticas , Biología Marina , Selección Genética , Animales , Antozoos/fisiología , Geografía , Océano Índico , Jordania , Dinámica Poblacional
12.
J Appl Microbiol ; 100(1): 175-84, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-16405698

RESUMEN

AIMS: To determine the genetic relatedness of Campylobacter spp. from retail meat products, and compare the discriminatory power of pulsed-field gel electrophoresis (PFGE) and automatic ribotyping. METHODS AND RESULTS: A total of 378 Campylobacter isolates recovered from 159 raw meats (130 chicken, 25 turkey, three pork and one beef) sampled from 50 retail grocery stores of four supermarket chains in the Maryland suburban area from August 1999 to July 2000 were analysed by PFGE with SmaI, 120 isolates of which were also characterized by ribotyping with PstI using RiboPrinter system. A total of 148 unique PFGE patterns were identified, 91 of which were present in multiple Campylobacter isolates and 24 in multiple meat samples. Nineteen Campylobacter clones with identical PFGE patterns recurred frequently (up to nine times) throughout the sampling period. Comparing ribotyping with PFGE, we identified 44 PFGE patterns and 22 RiboGroups among the 120 isolates tested. Multiple PFGE patterns within one RiboGroup were commonly observed, as well as multiple RiboGroups within one PFGE pattern. CONCLUSIONS: Although Campylobacter present in retail meats were genetically diverse, certain clones persisted in poultry meats. PFGE had a greater discriminatory power than ribotyping, and the two methods were complementary in genotyping Campylobacter. SIGNIFICANCE AND IMPACT OF THE STUDY: Genomic DNA fingerprinting of Campylobacter confirmed diverse and recurrent Campylobacter clones in the retail meats, which provides additional data for a better understanding of the epidemiological aspect of Campylobacter infection.


Asunto(s)
Campylobacter/genética , Electroforesis en Gel de Campo Pulsado/métodos , Microbiología de Alimentos , Carne/microbiología , Ribotipificación/métodos , Animales , Campylobacter coli/genética , Campylobacter jejuni/genética , Bovinos , Pollos , Medios de Cultivo , Variación Genética/genética , Genotipo , Porcinos , Pavos
13.
Proc Natl Acad Sci U S A ; 100(21): 12229-34, 2003 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-14512513

RESUMEN

The structure of ecological communities reflects a tension among forces that alter populations. Marine ecologists previously emphasized control by locally operating forces (predation, competition, and disturbance), but newer studies suggest that inputs from large-scale oceanographically modulated subsidies (nutrients, particulates, and propagules) can strongly influence community structure and dynamics. On New Zealand rocky shores, the magnitude of such subsidies differs profoundly between contrasting oceanographic regimes. Community structure, and particularly the pace of community dynamics, differ dramatically between intermittent upwelling regimes compared with relatively persistent down-welling regimes. We suggest that subsidy rates are a key determinant of the intensity of species interactions, and thus of structure in marine systems, and perhaps also nonmarine communities.


Asunto(s)
Ecosistema , Biología Marina , Oceanografía , Animales , Bivalvos , Equinodermos , Nueva Zelanda , Dinámica Poblacional , Thoracica
14.
J Microbiol Methods ; 54(3): 315-23, 2003 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-12842478

RESUMEN

Adherence to the tooth surface by Streptococcus mutans is an important step in initiation of dental caries. Current in vitro methods used to study bacterial adherence are time-consuming and may involve the use of radiolabels. The aim of this study was to develop a more convenient, high-throughput, microtitre-plate assay of bacterial adherence to hydroxylapatite. S. mutans was labelled with the fluorescent indicator BCECF/AM and fluorescence measured using a spectrofluorometer. Fluorescence microscopy confirmed label uptake. Optimal labelling occurred at 120 min with 50 microM BCECF/AM in DMSO. Viability was similar in control untreated bacterial cells, bacteria treated with DMSO alone or with the label for up to 4 h. Preliminary adherence experiments were performed using four commercially available types of hydroxylapatite. Fluorescence from pre-labelled bacteria was measured for bound cells. The assay was then optimised with respect to time and bacterial concentration using Fluka crude hydroxylapatite. Time course studies demonstrated that adherence reached saturation by 30 min incubation when using 1x10(7) cfu/ml labelled bacteria to 1 mg hydroxylapatite, coated with PBS or saliva. The fluorescence-based adherence assay was highly reproducible in repeated analyses and was useful in demonstrating interference with adherence. In conclusion, this microtitre-plate assay offers a more convenient approach to examine streptococcal adherence and could be used to screen for potential anti-adhesive agents.


Asunto(s)
Adhesión Bacteriana/fisiología , Durapatita/metabolismo , Espectrometría de Fluorescencia/métodos , Streptococcus mutans/fisiología , Caries Dental/microbiología , Proteínas del Huevo/fisiología , Fluoresceínas/metabolismo , Humanos , Saliva/fisiología
15.
Microb Drug Resist ; 8(2): 139-46, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-12118519

RESUMEN

Fifty isolates of Escherichia coli serogroup O111 recovered from humans and various animal species over a 24-year period (1976-1999) were examined for typical virulence-associated factors and susceptibilities to antimicrobials of human and veterinary significance. Nine H (flagellar) types were identified including nonmotile (n = 24), 32 (n = 12), negative (n = 5), and 56 (n = 3). Thirty-five (70%) isolates possessed at least one Shiga-toxin-producing E. coli (STEC)-associated virulence determinants (eae, stxl, stx2, hlyA) via PCR analysis. Of these 35 isolates, 20 possessed eae, stxl, and hlyA genes, whereas three isolates possessed eae, stxl, stx2, and hylA genes. Multiple antibiotic resistance was observed in 70% of the 50 E. coli O111 isolates. The majority of isolates displayed resistance to streptomycin, sulfamethoxazole, tetracycline, and kanamycin. Bacterial resistance to ampicillin, gentamicin, chloramphenicol, trimethoprim and apramycin was also observed. Integrons were identified in 23 (46%) of the E. coli isolates assayed, with a 1-kb amplicon being most frequently observed. DNA sequencing of these integrons revealed the presence of the aadA gene, encoding resistance to streptomycin. Two integrons of 1.5 and 2 kb contained the aadA2 and either dfrI or dfrXII genes, encoding resistance to streptomycin and trimethoprim, respectively. Integrons were also identified from isolates dating back to 1982. Isolates were further genetically characterized via ribotyping, which identified 15 distinct ribogroups, with 62% of isolates clustering into four major ribogroups. Certain riboprint patterns from different animal species, including humans, were observed in isolates spanning the 24-year collection period, suggesting the dissemination of specialized pathogenic O111 clones.


Asunto(s)
Antibacterianos/farmacología , Escherichia coli/efectos de los fármacos , Animales , ADN Bacteriano/genética , Farmacorresistencia Microbiana , Escherichia coli/genética , Escherichia coli/patogenicidad , Escherichia coli O157/efectos de los fármacos , Escherichia coli O157/genética , Genes Bacterianos/genética , Humanos , Integrinas/genética , Pruebas de Sensibilidad Microbiana , Fenotipo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Ribotipificación
16.
Nature ; 413(6853): 255, 2001 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-11565008
18.
Evolution ; 55(2): 295-306, 2001 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11308087

RESUMEN

In many nonclonal, benthic marine species, geographic distribution is mediated by the dispersal of their larvae. The dispersal and recruitment of marine larvae may be limited by temperature gradients that can affect mortality or by ocean currents that can directly affect the movements of pelagic larvae. We focus on Point Conception, a well-known biogeographic boundary between the Californian and Oregonian biogeographic provinces, to investigate whether ocean currents affect patterns of gene flow in intertidal marine invertebrates. The predominance of pelagically dispersing species with northern range limits at Point Conception suggests that ocean currents can affect species distributions by erecting barriers to the dispersal of planktonic larvae. In this paper, we investigate whether the predominantly southward currents have left a recognizable genetic signature in species with pelagically dispersing larvae whose ranges span Point Conception. We use patterns of genetic diversity and a new method for inferring cladistic migration events to test the hypothesis that southward currents increase southward gene flow for species with pelagically dispersing larvae. We collected mitochondrial DNA (mtDNA) sequence data for the barnacles Balanus glandula and Chthamalus fissus and also reanalyzed a previously published mtDNA dataset (Strongylocentrotus purpuratus, Edmands et al. 1996). For all three species, our cladistic approach identified an excess of southward migration events across Point Conception. In data from a fourth species with nondispersing larvae (Nucella emarginata, Marko 1998), our method suggests that ocean currents have not played a role in generating genetic structure.


Asunto(s)
Crustáceos/genética , Geografía , Modelos Genéticos , Moluscos/genética , Plantas Medicinales , Erizos de Mar/genética , Animales , California , ADN Mitocondrial/química , Complejo IV de Transporte de Electrones/genética , Emigración e Inmigración , Genotipo , Larva , Oceanografía , Oregon , Reacción en Cadena de la Polimerasa/veterinaria
19.
Appl Environ Microbiol ; 67(4): 1558-64, 2001 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11282605

RESUMEN

A total of 50 isolates of Shiga toxin-producing Escherichia coli (STEC), including 29 O157:H7 and 21 non-O157 STEC strains, were analyzed for antimicrobial susceptibilities and the presence of class 1 integrons. Seventy-eight (n = 39) percent of the isolates exhibited resistance to two or more antimicrobial classes. Multiple resistance to streptomycin, sulfamethoxazole, and tetracycline was most often observed. Class 1 integrons were identified among nine STEC isolates, including serotypes O157:H7, O111:H11, O111:H8, O111:NM, O103:H2, O45:H2, O26:H11, and O5:NM. The majority of the amplified integron fragments were 1 kb in size with the exception of one E. coli O111:H8 isolate which possessed a 2-kb amplicon. DNA sequence analysis revealed that the integrons identified within the O111:H11, O111:NM, O45:H2, and O26:H11 isolates contained the aadA gene encoding resistance to streptomycin and spectinomycin. Integrons identified among the O157:H7 and O103:H2 isolates also possessed a similar aadA gene. However, DNA sequencing revealed only 86 and 88% homology, respectively. The 2-kb integron of the E. coli O111:H8 isolate contained three genes, dfrXII, aadA2, and a gene of unknown function, orfF, which were 86, 100, and 100% homologous, respectively, to previously reported gene cassettes identified in integrons found in Citrobacter freundii and Klebsiella pneumoniae. Furthermore, integrons identified among the O157:H7 and O111:NM strains were transferable via conjugation to another strain of E. coli O157:H7 and to several strains of Hafnia alvei. To our knowledge, this is the first report of integrons and antibiotic resistance gene cassettes in STEC, in particular E. coli O157:H7.


Asunto(s)
Antibacterianos/farmacología , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Integrasas/genética , Toxinas Shiga/biosíntesis , Animales , Bovinos , Conjugación Genética , Farmacorresistencia Microbiana/genética , Electroforesis en Gel de Campo Pulsado , Escherichia coli O157/efectos de los fármacos , Escherichia coli O157/genética , Humanos , Pruebas de Sensibilidad Microbiana , Plásmidos/genética , Reacción en Cadena de la Polimerasa
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