RESUMEN
In Portugal, listeriosis has been notifiable since April 2014, but there is no active surveillance programme for the disease. A retrospective study involving 25 national hospitals led to the detection of an outbreak that occurred between March 2009 and February 2012. The amount of time between the start of the outbreak and its detection was 16 months. Of the 30 cases of listeriosis reported, 27 were in the Lisbon and Vale do Tejo region. Two cases were maternal/neonatal infections and one resulted in fetal loss. The mean age of the non-maternal/neonatal cases was 59 years (standard deviation: 17); 13 cases were more than 65 years old. The case fatality rate was 36.7%. All cases were caused by molecular serogroup IVb isolates indistinguishable by pulsed-field gel electrophoresis and ribotype profiles. Collaborative investigations with the national health and food safety authorities identified cheese as the probable source of infection, traced to a processing plant. The magnitude of this outbreak, the first reported food-borne listeriosis outbreak in Portugal, highlights the importance of having an effective listeriosis surveillance system in place for early detection and resolution of outbreaks, as well as the need for a process for the prompt submission of Listeria monocytogenes isolates for routine laboratory typing.
Asunto(s)
Queso/virología , Brotes de Enfermedades , Contaminación de Alimentos/análisis , Enfermedades Transmitidas por los Alimentos/epidemiología , Listeria monocytogenes/aislamiento & purificación , Listeriosis/epidemiología , Adolescente , Adulto , Anciano , Electroforesis en Gel de Campo Pulsado , Femenino , Microbiología de Alimentos , Inocuidad de los Alimentos , Enfermedades Transmitidas por los Alimentos/microbiología , Humanos , Listeria monocytogenes/clasificación , Listeria monocytogenes/genética , Listeriosis/microbiología , Persona de Mediana Edad , Portugal/epidemiología , Estudios Retrospectivos , Ribotipificación , Vigilancia de Guardia , SerotipificaciónRESUMEN
Listeria monocytogenes is responsible for severe and often fatal food-borne infections in humans. A collection of 2,421 L. monocytogenes isolates originating from Ontario's food chain between 1993 and 2010, along with Ontario clinical isolates collected from 2004 to 2010, was characterized using an improved multilocus variable-number tandem-repeat analysis (MLVA). The MLVA method was established based on eight primer pairs targeting seven variable-number tandem-repeat (VNTR) loci in two 4-plex fluorescent PCRs. Diversity indices and amplification rates of the individual VNTR loci ranged from 0.38 to 0.92 and from 0.64 to 0.99, respectively. MLVA types and pulsed-field gel electrophoresis (PFGE) patterns were compared using Comparative Partitions analysis involving 336 clinical and 99 food and environmental isolates. The analysis yielded Simpson's diversity index values of 0.998 and 0.992 for MLVA and PFGE, respectively, and adjusted Wallace coefficients of 0.318 when MLVA was used as a primary subtyping method and 0.088 when PFGE was a primary typing method. Statistical data analysis using BioNumerics allowed for identification of at least 8 predominant and persistent L. monocytogenes MLVA types in Ontario's food chain. The MLVA method correctly clustered epidemiologically related outbreak strains and separated unrelated strains in a subset analysis. An MLVA database was established for the 2,421 L. monocytogenes isolates, which allows for comparison of data among historical and new isolates of different sources. The subtyping method coupled with the MLVA database will help in effective monitoring/prevention approaches to identify environmental contamination by pathogenic strains of L. monocytogenes and investigation of outbreaks.
Asunto(s)
Variación Genética , Listeria monocytogenes/clasificación , Listeria monocytogenes/genética , Repeticiones de Minisatélite , Tipificación Molecular/métodos , Análisis por Conglomerados , Cartilla de ADN/genética , Electroforesis en Gel de Campo Pulsado , Microbiología de Alimentos , Genotipo , Humanos , Listeria monocytogenes/aislamiento & purificación , Listeriosis/microbiología , OntarioRESUMEN
Canadian cases and outbreaks of illness caused by Listeria monocytogenes between 1995 and 2004 were assessed. Isolates (722 total) were characterized by serotyping, and pulsed-field gel electrophoresis (PFGE) was performed to provide a means of detecting case clusters. Rates of listeriosis remained fairly consistent during the period of study, and patient characteristics were similar to those seen in studies of other populations. Most isolates were obtained from blood and cerebrospinal fluid, although during some outbreak investigations isolates were also obtained from stools. Serotype 1/2a predominated in isolates from patients in Canada, followed by serotypes 4b and 1/2b. Outbreaks caused by L. monocytogenes that occurred during the period of study were caused by isolates with serotypes 1/2a and 4b. A retrospective analysis of PFGE data uncovered several clusters that might have represented undetected outbreaks, suggesting that comprehensive prospective PFGE analysis coupled with prompt epidemiological investigations might lead to improved outbreak detection and control.
Asunto(s)
Listeria monocytogenes/aislamiento & purificación , Listeriosis/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Técnicas de Tipificación Bacteriana , Sangre/microbiología , Canadá/epidemiología , Líquido Cefalorraquídeo/microbiología , Niño , Preescolar , Análisis por Conglomerados , Dermatoglifia del ADN , Brotes de Enfermedades , Electroforesis en Gel de Campo Pulsado , Femenino , Genotipo , Humanos , Incidencia , Listeria monocytogenes/clasificación , Listeria monocytogenes/genética , Listeriosis/microbiología , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Serotipificación , Adulto JovenRESUMEN
Listeriosis is a serious foodborne disease caused by Listeria monocytogenes, a pathogen often found in food processing plants. Poultry meat and its derivatives may harbor L. monocytogenes even if good manufacturing practices are implanted in abattoirs. Little information exists in Brazil on the frequency of L. monocytogenes contamination, even though the country is considered the top poultry meat exporter in the world. This study attempted to compare 2 exporters poultry facilities following same the standards but differing only in manual (plant M) or automatic (plant A) evisceration. Eight hundred fifty-one samples from food, food contact and non-food contact surfaces, water, and workers' hands were collected from cage to finished products over a 1-yr period. In plant A, 20.1% of the samples were positive for L. monocytogenes, whereas in plant M, 16.4% was found. The greatest incidence of contamination with the pathogen in plant A was found in non-food contact surfaces (27.3%), while in plant M, it was found in products (19.4%). The most prevalent serovars were 1/2a or 3a (plant M) and 4b, 4d, or 4e (plant A). Despite having proper hygiene and good manufacturing practices, controlling the entry and persistence of L. monocytogenes in processing facilities remains a formidable task.
Asunto(s)
Mataderos , Manipulación de Alimentos/métodos , Listeria monocytogenes/aislamiento & purificación , Carne/microbiología , Animales , Automatización , PollosRESUMEN
The present study compared the sensitivity of the BAX automated fluorometric and the recently discontinued BAX gel electrophoresis systems with a standard culture method to detect Salmonella in 333 high-moisture and 171 low-moisture foods. A total of 95 naturally contaminated foods, including 63 high-moisture and 32 low-moisture foods, were detected by the standard culture method. No contaminated samples were identified exclusively by the BAX systems. By means of the analytical protocol stipulated by the manufacturer, the BAX fluorometric system detected 36 (57.1%) and 29 (90.6%) of the contaminated high- and low-moisture foods, respectively. Similar results were obtained with the BAX gel electrophoresis system, which identified 40 (63.5%) and 26 (81.3%) of the contaminated high- and low-moisture foods. The rate of false-positive reactions with the BAX systems was low. Our results indicate that the low sensitivity of the BAX systems with high-moisture foods, notably raw meats and poultry products, was serovar-independent. The high levels of background microflora that commonly occur in raw meat and on fresh fruit and vegetable products, and the high successive dilutions of test materials for PCR analysis, suggestively undermined the sensitivity of the gel and the fluorometric BAX assays. The potential benefits of immunomagnetic separation of Salmonella in preenrichment cultures, of selective broth enrichment following preenrichment to markedly reduce levels of background microflora in PCR test materials, and the use of larger portions of test materials in PCR analyses should be investigated.
Asunto(s)
Fluorometría/normas , Contaminación de Alimentos/análisis , Microbiología de Alimentos , Productos de la Carne/microbiología , Salmonella/aislamiento & purificación , Recuento de Colonia Microbiana , Seguridad de Productos para el Consumidor , Electroforesis en Gel de Agar/métodos , Electroforesis en Gel de Agar/normas , Reacciones Falso Positivas , Fluorometría/métodos , Humanos , Separación Inmunomagnética/métodos , Separación Inmunomagnética/normas , Reacción en Cadena de la Polimerasa/métodos , Reacción en Cadena de la Polimerasa/normas , Reproducibilidad de los Resultados , Intoxicación Alimentaria por Salmonella , Sensibilidad y EspecificidadRESUMEN
An origin of replication (ori) was obtained from a naturally occurring beta-lactamase-producing plasmid isolated from Neisseria gonorrhoeae and used to construct shuttle vectors capable of replicating in N. gonorrhoeae, Haemophilus ducreyi, Haemophilus influenzae and Escherichia coli. Using the gonococcal proAB genes, we complemented proline-requiring N. gonorrhoeae F62 and E. coli HB101 in trans. The first demonstration of the expression of the green fluorescent protein (GFP) in either N. gonorrhoeae or H. ducreyi was shown using this vector, indicating that GFP may be a useful tool in the analysis of these organisms. This is the first report of a gonococcal vector based on a broad host range, genetically defined ori, and should facilitate the molecular analysis of gonococcal and Haemophilus genes.
Asunto(s)
Vectores Genéticos/genética , Haemophilus/genética , Neisseria gonorrhoeae/genética , Origen de Réplica , Bacterias/genética , ADN Recombinante , Escherichia coli/genética , Prueba de Complementación Genética , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/genética , Proteínas Recombinantes de Fusión/genética , Transformación GenéticaRESUMEN
The beta-lactamase-producing Asia-type plasmid pJD4 of Neisseria gonorrhoeae is a 7.4-kb, broad-host-range plasmid. It is part of a family of plasmids which are structurally related yet vary in size, found in both N. gonorrhoeae and Haemophilus ducreyi. Branch-point analysis by electron microscopy indicates that pJD4 carries three clustered but distinguishable origins of replication, which we named ori1, ori2, and ori3. Although pJD4 belongs to incompatibility (Inc) group W, it also carries a silent IncFII determinant which is expressed when ori2 and ori3 are absent. The Africa-type plasmid pJD5, a naturally occurring deletion derivative of pJD4, carries only ori1, belongs to the IncFII group, and, in contrast to pJD4, requires DNA polymerase I (Pol I) for replication. Plasmids constructed from pJD4 which lack ori1 but carry ori2 and ori3 do not require Pol I and are incompatible with IncW plasmids, suggesting that the ori2 or ori3 region contains the IncW determinant. We have cloned a replication initiation protein (RepB) that is necessary for ori2 and ori3 to function. This Rep protein is distinct from RepA, which is necessary for ori1. Thus, pJD4 is unique because it is the smallest plasmid characterized containing three origins of replication and two unique Rep proteins.
Asunto(s)
Replicación del ADN , Neisseria gonorrhoeae/enzimología , Plásmidos/genética , Origen de Réplica/genética , beta-Lactamasas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Secuencia de Bases , ADN Polimerasa I/genética , ADN Polimerasa I/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Escherichia coli/genética , Microscopía Electrónica , Datos de Secuencia Molecular , Neisseria gonorrhoeae/genética , Plásmidos/metabolismo , Regiones Promotoras Genéticas/genética , Proteína de Replicación A , Análisis de Secuencia de ADN , beta-Lactamasas/genéticaRESUMEN
Neisseria gonorrhoeae isolates continue to develop an impressive arsenal of resistance mechanisms to antimicrobial agents, including resistance to some of the antibiotics presently recommended for the treatment of gonococcal infections.
RESUMEN
Various retail and environmental sponges were tested for inhibitory properties against Listeria species and several other bacterial genera. Sterile sponges, unrinsed and rinsed in sterile distilled water or sterile neutralizing buffer, were placed on seeded plates of tryptic soy agar with 0.6% yeast extract. Plates were incubated at 30 degrees C for 24 h and zones of inhibition measured. The Systems Plus environmental sponge and the Technical Service Consultants Ltd sponge (sTc) proved to be the only sponges which consistently demonstrated no inhibitory properties. Results using scanning electron microscopy showed considerable bacterial attachment to the Systems Plus sponge, further corroborating these findings.
Asunto(s)
Desinfección/instrumentación , Inspección de Alimentos/métodos , Microbiología de Alimentos , Listeria/crecimiento & desarrollo , Listeria/efectos de los fármacos , Listeria/aislamiento & purificación , Microscopía Electrónica de RastreoRESUMEN
The exact nature of the sequence differences between the medically important family of gonococcal penicillinase-producing plasmids has been ascertained. The entire DNA sequence of the Asia-type plasmid, pJD4, demonstrated that it is 7426 bp and contains two direct repeats (DR30) that are implicated in the formation of deletion variant plasmids, such as the Africa-type plasmid. We have identified putative DnaA and IHF binding sites, various open reading frames that are thought to specify functional proteins, and some important DNA sequences involved with conjugative transfer of gonococcal beta-lactamase plasmids. The deletion in the Africa-type plasmid is 1827 bp and one of the DR30 repeats is also missing. The deletion in the Rio-type plasmid and several Toronto-type plasmids was determined to be 2273 bp and the sequence spanning the deletion was identical irrespective of geographic or temporal origin. The &Ncirc;imes-type plasmid is an Africa-type plasmid and also contains an IS5 insertion sequence. Since IS5 has not been identified in gonococcal isolates, we suggest that this sequence may have been inserted after the original gonococcal plasmid was transformed into Escherichia coli. The New Zealand plasmid is an Asia-type plasmid that contains an endogenous tandem duplication of 1883 bp and the direct DR2 is implicated in this duplication. The nature of the defined truncation of Tn2 present in the various plasmids is also discussed.
Asunto(s)
Neisseria gonorrhoeae/enzimología , Neisseria gonorrhoeae/genética , Penicilinasa/biosíntesis , Penicilinasa/genética , Plásmidos/genética , Secuencia de Bases , Elementos Transponibles de ADN/genética , ADN Bacteriano/genética , Variación Genética , Secuencias Repetitivas de Ácidos Nucleicos , Análisis de Secuencia de ADN , Eliminación de SecuenciaRESUMEN
Putative integration host factor (IHF) binding sites are frequently being identified in Neisseria gene sequences on the basis of similarity to a degenerate Escherichia coli -derived consensus binding sequence. In this report, three different Neisseria genetic systems that contain predicted IHF binding sites were assessed for IHF binding through gel retardation analysis. The results show a positive correlation between the identification of a predicted Neisseria IHF binding site and in vitro binding of Neisseria -derived IHF protein.