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The major histocompatibility complex (MHC) enables vertebrates to cope with pathogens and maintain healthy populations, thus making it a unique set of loci for addressing ecology and evolutionary biology questions. The aim of our study was to examine the variability of Heermann’s Gull MHC class II (MHCIIB) and compare these loci with other Charadriiformes. Fifty-nine MHCIIB haplotypes were recovered from sixty-eight Heermann’s Gulls by cloning, of them, twelve were identified as putative true alleles, forty-five as unique alleles, and two as pseudogenes. Intra and interspecific relationships indicated at least two loci in Heermann’s Gull MHCIIB and trans-species polymorphism among Charadriiformes (coinciding with the documented evidence of two ancient avian MHCIIB lineages, except in the Charadriidae family). Additionally, sites under diversifying selection revealed a better match with peptide-binding sites inferred in birds than those described in humans. Despite the negative anthropogenic activity reported on Isla Rasa, Heermann’s Gull showed MHCIIB variability consistent with population expansion, possibly due to a sudden growth following conservation efforts. Duplication must play an essential role in shaping Charadriiformes MHCIIB variability, buffering selective pressures through balancing selection. These findings suggest that MHC copy number and protected islands can contribute to seabird conservation.

Rhodococcus is a pathogen that is known to cause infections in animals and humans, mainly in cases of immunocompromised patients. A case of a pediatric cancer patient suffering from a bloodstream infection caused by Rhodococcus corynebacterioides was described in this work. Gram positive rods were isolated from blood cultures. The target bacterium was identified using a combination of biochemical tests, the MALDI-TOF mass spectrometry technique, and the analysis of the 16S rRNA sequence. Moreover, an antimicrobial susceptibility test was performed using the E-test. The isolated bacterium was identified as R. corynebacterioides. The 3-year-old patient was successfully treated with vancomycin and meropenem. This is the first published report of R. corynebacterioides in a pediatric patient diagnosed with retinoblastoma that developed a bloodstream infection. R. corynebacterioides should be considered among the opportunistic infectious agents affecting pediatric cancer patients.

Microbiomes are defined as complex microbial communities, which are mainly composed of bacteria, fungi, and viruses residing in diverse regions of the human body. The human stomach consists of a unique and heterogeneous habitat of microbial communities owing to its anatomical and functional characteristics, that allow the optimal growth of characteristic bacteria in this environment. Gastric dysbiosis, which is defined as compositional and functional alterations of the gastric microbiota, can be induced by multiple environmental factors, such as age, diet, multiple antibiotic therapies, proton pump inhibitor abuse, H. pylori status, among others. Although H. pylori colonization has been reported across the world, chronic H. pylori infection may lead to serious consequences; therefore, the infection must be treated. Multiple antibiotic therapy improvements are not always successful because of the lack of adherence to the prescribed antibiotic treatment. However, the abuse of eradication treatments can generate gastric dysbiotic states. Dysbiosis of the gastric microenvironment induces microbial resilience, due to the loss of relevant commensal bacteria and simultaneous colonization by other pathobiont bacteria, which can generate metabolic and physiological changes or even initiate and develop other gastric disorders by non-H. pylori bacteria. This systematic review opens a discussion on the effects of multiple environmental factors on gastric microbial communities.

El agua es el vehículo por el cual se transportan diversos tipos de desechos provenientes de diferentes actividades productivas, de tal forma que ríos, canales, lagunas y mares se contaminan con éstos. Esta situación se ha presentado en México desde hace más de 200 años, y en la actualidad se están generando nuevos contaminantes no reglamentados en las aguas de reúso o tratadas. En el caso de residuos de fármacos, su persistencia y entrada continua a mantos acuíferos originan efectos negativos sobre la vida y el ambiente acuático, debido a que no se eliminan totalmente en los procesos de tratamiento de aguas residuales a causa de su estabilidad química. Este tipo de agua se reutiliza para la producción de agua potable o el riego de zonas agrícolas, de manera que la salud humana y animal se encuentran expuestas a los efectos toxicológicos de este tipo de sustancias químicas. Se realizó la búsqueda de reportes acerca de la contaminación de residuos farmacológicos en diferentes tipos de agua —residual o no— y suelos agrícolas, tanto internacionales como nacionales, de 1984 a 2018. Se concluyó que no hay hasta hoy una normatividad nacional ni internacional idónea sobre la forma en que debe realizarse la eliminación de este tipo de desechos para al medio ambiente en la menor medida posible.

As dendritic cells (DCs) are among the first cells to encounter antigens, these cells trigger both innate and T cell responses, and are the most potent antigen-presenting cells. Brucella spp., which is an intracellular facultative and stealthy pathogen, is able to evade the bactericidal activities of professional phagocytes. Several studies have demonstrated that Brucella can survive and replicate intracellularly, thereby provoking impaired maturation of DCs. Therefore, the interaction between DCs and Brucella becomes an interesting model to study the immune response. In this review, we first will describe the most common techniques for DCs differentiation in vitro as well as general features of brucellosis. Then, the interaction of DCs and Brucella, including pathogen recognition, molecular mechanisms of bacterial pathogenesis, and intracellular trafficking of Brucella to subvert innate response, will be reviewed. Finally, we will debate diversity in immunological DC response and the controversial role of DC activation against Brucella infection.

Outer membrane vesicles (OMVs) from Gram-negative bacteria were first described more than 50 years ago. However, the molecular mechanisms involved in biogenesis began to be studied only in the last few decades. Presently, the biogenesis and molecular mechanisms for their release are not completely known. This review covers the most recent information on cellular components involved in OMV biogenesis, such as lipoproteins and outer membrane proteins, lipopolysaccharide, phospholipids, quorum-sensing molecules, and flagella. CONACYTConsejo Nacional de Ciencia y Tecnologia (CONACyT) [61529]; SIP-IPN [20182152, 20195737, 20200594]; SAGARPA-CONACYTConsejo Nacional de Ciencia y Tecnologia (CONACyT) [2017-02-291311]; PIFI-IPN scholarships; COFAA-IPN; SIP-EDI; SNI-CONACYTConsejo Nacional de Ciencia y Tecnologia (CONACyT) This work was funded by CONACYT 61529, SIP-IPN 20182152, 20195737, 20200594, and SAGARPA-CONACYT 2017-02-291311. EA-C was supported by CONACYT and PIFI-IPN scholarships. MA-A, ER, ZG-L, and AC-R were supported by fellowships from COFAA-IPN, SIP-EDI, and SNI-CONACYT.

Fish feed should be characterized by microbiological stability to guarantee the optimal health of farmed fish. The aim of this study was to determine the efficacy of amaranth meal (Amaranthus cruentus) and a highly active environmental strain of probiotic bacteria, Carnobacterium maltaromaticum, as novel supplements that stabilize the quantitative and qualitative composition of microbiota in compound fish feeds for aquaculture, regardless of storage temperature. The total viable counts of mesophilic bacteria at 28 &deg, C (TVC 28 &deg, C), hemolytic mesophilic bacteria (Hem 37 &deg, C), Staphylococcus sp. bacteria, aerobic spore-forming bacteria (ASFB), sulfite-reducing anaerobic spore-forming Clostridium sp. bacteria, yeasts, and molds were analyzed in control feed (CF), in feed supplemented with amaranth meal (AF), and in feed supplemented with amaranth meal and C. maltaromaticum (ACF), stored at a temperature of 4 &deg, C and 20 &deg, C for 98 days. Amaranthus cruentus and C. maltaromaticum significantly reduced bacterial counts in fish feeds, regardless of the temperature and duration of storage. The antibacterial and antifungal effects of the tested additives were statistically significant (p &le, 0.05). The studied novel supplements contribute to the microbiological safety of compound fish feeds. The tested additives could be recognized as the key ingredients of organic, environmentally friendly fish feeds, which guarantee the high quality of fish intended for human consumption.

Introducción: La brucelosis es una de las enfermedades zoonóticas más frecuentes en la mayor parte del mundo. Mientras que en los países desarrollados han logrado con éxito su control, en los países en vías de desarrollo continúa siendo un gran problema de salud pública. México continúa presentando alta incidencia anual de brucelosis en humanos, por lo que es considerado un país endémico de brucelosis. Objetivo: Describir la relación de esta zoonosis con la situación epidemiológica actual en la población de México. Material y Métodos: Consulta de reportes de investigación, estudios epidemiológicos y revisiones veterinarias, realizadas en México, a través de bases de datos como PubMed, Thompson Reuters y Meshresearch. Conclusión: El riesgo del contagio de Brucella spp. en México está asociado al consumo de productos lácteos sin pasteurizar, principalmente quesos frescos.

Fresh cheeses are a main garnish of Mexican food. Consumption of artisanal fresh cheeses is very common and most of them are made from unpasteurised cow milk. A total of 52 fresh unpasteurised cheeses of five different types were purchased from a variety of suppliers from Tabasco, Mexico. Using the most probable number method, 67% and 63% of samples were positive for faecal coliforms and E. coli, respectively; revealing their low microbiological quality. General hygienic conditions and practices of traditional cheese manufacturers were poor; most establishments had unclean cement floors, all lacked windows and doors screens, and none of the food-handlers wore aprons, surgical masks or bouffant caps. After analysing all E. coli isolates (121 strains) for the presence of 26 virulence genes, results showed that 9 (17%) samples were contaminated with diarrheagenic E. coli strains, 8 harboured non-O157 Shiga toxin producing E. coli (STEC), and one sample contained both STEC and diffusely adherent E. coli strains. All STEC strains carried the stx1 gene. Potential uropathogenic E. coli (UPEC) strains were isolated from 15 (29%) samples; the most frequent gene combination was fimA-agn43. Two samples were contaminated with Salmonella. The results demonstrated that unpasteurised fresh cheeses produced in Tabasco are of poor microbiological quality and may frequently harbour foodborne pathogens. Food safety authorities in Mexico need to conduct more rigorous surveillance of fresh cheeses. Furthermore, simple and inexpensive measures as establishing programs emphasizing good hand milking practices and hygienic manufacturing procedures may have a major effect on improving the microbiological quality of these food items.

Estimations on the influence of evolutionary and ecological forces as drivers of population gene diversity and genetic structure have been performed on a growing number of colonial seabirds, but many remain poorly studied. In particular, the population genetic structure of storm-petrels (Hydrobatidae) has been evaluated in only a few of the 24 recognized species. We assessed the genetic diversity and population structure of the Black Storm-Petrel ( Hydrobates melania) and the Least Storm-Petrel ( Hydrobates microsoma) in the Gulf of California. The two species were selected because they are pelagic seabirds with comparable ecological traits and breeding grounds. Recent threats such as introduced species of predators and human disturbance have resulted in a decline of many insular vertebrate populations in this region and affected many different aspects of their life histories (ranging from reproductive success to mate selection), with a concomitant loss of genetic diversity. To elucidate to what extent the population genetic structure occurs in H. melania and H. microsoma, we used 719 base pairs from the mitochondrial cytochrome oxidase c subunit I gene. The evaluation of their molecular diversity, genetic structure, and gene flow were performed through diversity indices, analyses of molecular and spatial variance, and isolation by distance (IBD) across sampling sites, respectively. The population genetic structure (via AMOVA and SAMOVA) and isolation by distance (pairwise p-distances and FST/1– FST(using ΦST) were inferred for H. microsoma. However, for H. melania evidence was inconclusive. We discuss explanations leading to divergent population genetic structure signatures in these species, and the consequences for their conservation.

Anaerobic bacteria of the genus Bacteroides are a large group of commensal microorganisms that colonize the human and animal digestive tract. The genus Bacteroides and the closely related genus Parabacteroides include the Bacteroides fragilis group (BFG) of potentially pathogenic bacteria which are frequently isolated from patients with anaerobic infections.The aim of this study was to assess the antimicrobial resistance of environmental strains of the Bacteroides fragilis group. Strains were isolated from human feces, hospital wastewater, influent (UWW) and effluent (TWW) wastewater from a wastewater treatment plant (WWTP), and from the feces of lab rats as a negative control to monitor the entire route of transmission of BFG strains from humans to the environment. The resistance of 123 environmental BFG strains to six antibiotic groups was analyzed with the use of culture-dependent methods. Additionally, the presence of 25 genes encoding antibiotic resistance was determined by PCR.The analyzed environmental BFG strains were highly resistant to the tested antibiotics. The percentage of resistant strains differed between the analyzed antibiotics and was determined at 97.56% for ciprofloxacin, 49.59% for erythromycin, 44.71% for ampicillin, 35.77% for tetracycline, 32.52% for amoxicillin/clavulanic acid, 26.83% for chloramphenicol, 26.01% for clindamycin, 11.38% for moxifloxacin, and 8.94% for metronidazole. The highest drug-resistance levels were observed in the strains isolated from UWW and TWW samples. The mechanisms of antibiotic-resistance were determined in phenotypically resistant strains of BFG. Research has demonstrated the widespread presence of genes encoding resistance to chloramphenicol (100% of all chloramphenicol-resistant strains), tetracyclines (97.78% of all tetracycline-resistant strains), macrolides, lincosamides and streptogramins (81.97% of all erythromycin-resistant strains). Genes encoding resistance to β-lactams and fluoroquinolones were less prevalent. None of the metronidazole-resistant strains harbored the gene encoding resistance to nitroimidazoles. BFG strains isolated from UWW and TWW samples were characterized by the highest diversity of antibiotic-resistance genes and were most often drug-resistant and multidrug-resistant.The present study examines the potential negative consequences of drug-resistant and multidrug-resistant BFG strains that are evacuated with treated wastewater into the environment. The transmission of these bacteria to surface water bodies can pose potential health threats for humans and animals; therefore, the quality of treated wastewater should be strictly monitored. Keywords: Bacteroides fragilis group, Antimicrobial susceptibility, Antibiotic-resistance genes, Environmental strains

Outer membrane vesicles (OMVs) are released from the outer membrane of Gram-negative bacteria. Moreover, Gram-positive bacteria also produce membrane-derived vesicles. As OMVs transport several bacterial components, especially from the cell envelope, their interaction with the host cell, with other bacteria or as immunogens, have been studied intensely. Several functions have been ascribed to OMVs, especially those related to the transport of virulence factors, antigenic protein composition, and development as acellular vaccines. In this work, we review some of the recent findings about OMVs produced by specific pathogenic bacterial species.

Brucellosis is one of the most frequent zoonosis in most parts of the world. This zoonosis remains a great problem to public health in developing countries, although developed countries have successfully controlled it. Mexico still shows a high annual brucellosis incidence in humans; thus, the country is considered around the world as an endemic brucellosis country.To describe the connection/association between this zoonosis and the current epidemiological situation in the Mexican population.Perusal of research reports, epidemiological studies and veterinarian reviews performed in Mexico, using data bases such as PubMed, Thompson Reuters, Mesh research.The risk of infection by Brucella in Mexico is associated with the consumption of unpasteurized dairy products, mainly fresh cheeses.

Brucellosis is a zoonosis that affects many animal species worldwide. Humans are often infected through direct animal contact, through contact with animal excretions, or through ingestion of unpasteurized dairy products. Livestock manure is extensively used as a pasture fertilizer in many production systems, especially in non-developed countries. Some microbiological studies warn of the risk of manure being a disseminator vector of pathogenic microorganisms. The present study aimed to isolateBrucellain manure from cows and goats that were serologically positive for brucellosis in an endemic region of Mexico. We then used E-test methods to evaluate the isolated microorganisms' susceptibility to antimicrobial agentsin vitro. Brucellaisolation was performed via a pre-enriched selective culture, and subcultures using selective agar plates. Isolates were identified using microbiological tests as well as BCSP31 PCR and Bruce-Ladder multiplex PCR. We isolated 10Brucellaspp. strains, all of which amplified the genus-specific gene that encodes the BCSP31 protein. The species were identified using multiplex PCR. Interestingly,B. melitensis, B. abortus,andB. suiswere isolated from cow manure, whileB. abortuswas just isolated from goat manure. The isolates did not include any strains that are routinely vaccinated against. Some isolates were resistant to ciprofloxacin, levofloxacin, trimethoprim-sulfamethoxazole, and rifampicin. Manure from infected animals could represent a vehicle for human exposure toBrucella.More detailed studies are needed to evaluateBrucella-contaminated manure as a risk factor in endemic regions., La brucelosis es una zoonosis distribuida mundialmente que afecta varias especies animales. Los humanos se infectan por el contacto con animales infectados, sus excreciones o por la ingesta de derivados lácteos no pasteurizados. Las heces excretadas por el ganado se usan como fertilizante en países no desarrollados. Estudios microbiológicos han alertado sobre el riesgo de las heces o estiércol como vector de diseminación de microorganismos patógenos. El objetivo de este trabajo fue aislarBrucellade heces de vacas y cabras y evaluar la sensibilidad contra antimicrobianos mediante el método de E-test. Se analizaron heces de vacas y cabras serológicamente positivas a brucelosis de una región endémica de México. El aislamiento deBrucellase llevó a cabo en un medio de preenriquecimiento y posteriormente se aisló en medio selectivo. La identificación se realizó mediante pruebas microbiológicas y por PCR. Se obtuvieron 10 aislados deBrucellaspp., que fueron positivos a la amplificación del gen específico de género que codifica para la proteína BCSP31 y mediante multiplex Bruce-Ladder se identificó la especie. Se demostró la presencia deB. melitensis, B. abortusyB. suisen las heces de las vacas, mientras queB. abortussolo se aisló de las cabras. Ninguna cepa vacunal se encontró en el estudio. Algunos aislados fueron resistentes a ciprofloxacina, levofloxacina, trimetoprim-sulfametoxazol, y rifampicina. Las heces de animales infectados representan un riesgo de exposición aBrucella.Se requieren estudios más detallados para evaluar el factor de riesgo asociado a la materia fecal contaminada conBrucellaen regiones endémicas.

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Brucella abortus has been shown to produce two siderophores: 2,3-dihydroxybenzoic acid (2,3-DHBA) and brucebactin. Previous studies on Brucella have shown that 2,3-DHBA is associated with erythritol utilization and virulence in pregnant ruminants. The biosynthetic pathway and role of brucebactin are not known and the only gene shown to be involved so far is entF. Using cre-lox methodology, an entF mutant was created in wild-type B. abortus 2308. Compared with the wild-type strain, the ΔentF strain showed significant growth inhibition in iron minimal media that became exacerbated in the presence of an iron chelator. For the first time, we have demonstrated the death of the ΔentF strain under iron-limiting conditions in the presence of erythritol. Addition of FeCl(3) restored the growth of the ΔentF strain, suggesting a significant role in iron acquisition. Further, complementation of the ΔentF strain using a plasmid containing an entF gene suggested the absence of any polar effects. In contrast, there was no significant difference in survival and growth between the ΔentF and wild-type strains grown in the murine macrophage cell line J774A.1, suggesting that an alternate iron acquisition pathway is present in Brucella when grown intracellulary.

A 97-kDa purified aminopeptidase N (PepN) of Brucella melitensis was previously identified to be immunogenic in humans. The B. melitensis pepN gene was cloned, expressed in Escherichia coli and purified by affinity chromatography. The recombinant PepN (rPepN) exhibited the same biochemical properties, specificity and susceptibility to inhibitors as the native PepN. rPepN was evaluated as a diagnostic antigen in an indirect enzyme-linked immunosorbent assay (ELISA) using sera from patients with acute and chronic brucellosis. The specificity of the ELISA was determined with sera from healthy donors. The ELISA had a cutoff value of 0.156 with 100% specificity and 100% sensitivity. Higher sensitivity was obtained using rPepN compared with crude extract from B. melitensis. Anti-PepN sera did not exhibit serological cross-reaction to crude extracts from Rhizobium tropici, Ochrobactrum anthropi, Yersinia enterocolitica 09 or E. coli O157H7.

Importance of urease activity on pathogenic differences among Brucella species was evaluated. In cell-free extracts, the B. suis urease showed 12 times greater specific activity than the B. melitensis urease. When Fisher-344 rats were inoculated intraperitoneally (IP), at 1 week post-inoculation (PI), B. melitensis wild type 16 M was recovered from spleens and livers in greater numbers than B. suis wild type 1330. At 8 weeks PI, spleens were clear of B. melitensis, whereas B. suis remained. The wild type and the urease deficient strains of B. suis did not differ from each other in terms of recovery from spleen or liver. Our observations suggest that B. melitensis induces greater acute infectivity in Fisher-344 rats, whereas B. suis causes chronic infectivity; and urease activity has no influence on Brucella infection using an IP route.

An immunogenic aminopeptidase was purified from Brucella melitensis strain VTRM1. The purification procedure consisted of ammonium sulfate fractionation and three chromatographic steps. This procedure resulted in a yield of 29% and a 144-fold increase in specific activity. The aminopeptidase appeared to be a monomeric enzyme with a molecular mass of 96 kDa and an isoelectric point of 4.8. Its activity was optimal at pH 7.0 at 40°C. The enzyme was strongly inhibited by EDTA, 1,10-phenathroline, and divalent cations (Zn 2+ and Hg 2+ ), suggesting that this protein was a metalloaminopeptidase. The enzyme showed preference for alanine at the N termini of aminoacyl derivatives. The K m values for l -alanine- p -nitroanilide (Ala- p NA) and Lys- p NA were 0.35 and 0.18 mM, respectively. The N-terminal sequence of aminopeptidase was used for a homologous search in the genomes of B. melitensis 16M and Brucella suis 1330. The analysis revealed an exact match of the probe sequence (36 bp) with an open reading frame of 2,652 bp encoding a protein predicted to be alanyl aminopeptidase (aminopeptidase N). Collectively, these data suggest designation of the B. melitensis enzyme as an aminopeptidase N. The aminopeptidase was recognized by sera from patients with acute and chronic brucellosis, suggesting that the enzyme may have important diagnostic implications.

Biofilm formation on medical and surgical devices is the main virulence factor of Staphylococcus epidermidis. A recent study has shown that norspermidine inhibits and disassembles the biofilm in the wild-type Bacillus subtilis NCBI3610 strain. In this study, the effect of norspermidine on S. epidermidis biofilm formation of clinical or commensal strains was tested. Biofilm producing strains of S. epidermidis were isolated from healthy skin (HS; n = 3), healthy conjunctiva (HC; n = 9) and ocular infection (OI; n = 19). All strains were treated with different concentrations of norspermidine, spermidine, putrescine, and cadaverine (1, 10, 25, 50 and 100 μM), and the biofilm formation was tested on microtiter plate. Besides, cell-free supernatants of S. epidermidis growth at 4 h and 40 h were analyzed by gas chromatography coupled to mass spectrometry (GC–MS) to detect norspermidine. Results showed that norspermidine at 25 μM and 100 μM prevented the biofilm formation in 45.16% (14/31) and 16.13% (5/31), respectively; only in one isolate from OI, norspermidine did not have effect. Other polyamines as spermidine, putrescine and cadaverine did not have effect on the biofilm formation of the strains tested. Norspermidine was also capable to disassemble a biofilm already formed. Norspermidine was detected in the 40 h cell-free supernatant of S. epidermidis by GC–MS. Norspermidine inhibited the biofilm development of S. epidermidis on the surface of contact lens. In this work, it was demonstrated that S. epidermidis produces and releases norspermidine causing an inhibitory effect on biofilm formation. Moreover, this is the first time showing that clinical S. epidermidis strains have different sensitivity to norspermidine, which suggest that the composition and structure of the biofilms is varied. We propose that norspermidine could potentially be used in the pre-treating of medical and surgical devices to inhibit the biofilm formation.

Introducción: El diagnóstico de brucelosis humana es difícil pues los cultivos de sangre y tejidos tienen un rendimiento limitado (40-70%) y usualmente se recurre a la serología como recurso complementario; últimamente se han desarrollado técnicas de biología molecular que intentan optimizar la confirmación etiológica. Objetivo: Comparar la reacción de la polimerasa en cadena (RPC) con las pruebas de diagnóstico serológicas en el seguimiento clínico de una familia con brucelosis. Métodos: Siete integrantes de una familia con brucelosis que habitaban la zona urbana de Ciudad de México fueron monitoreados mediante aglutinación con antígeno Rosa de Bengala, prueba de aglutinación, aglutinación en presencia de 2 mercapto-etanol, hemocultivos y RPC en suero durante 27 meses. La probable fuente de infección de los pacientes fue el consumo de queso fresco de cabra originario de una zona endémica. Resultados: Brucella melitensis se obtuvo del hemocultivo de dos pacientes. Todos los pacientes fueron positivos a las pruebas serológicas y al RPC al inicio del seguimiento. Tres pacientes respondieron bien al tratamiento y mostraron resultados negativos en serología y RPC al final del estudio. Mientras que en dos pacientes con diabetes mellitus tipo 2 la sintomatología fue persistente, serología positiva y RPC positivos al finalizar el estudio. Conclusión: El seguimiento clínico de pacientes con brucelosis es muy importante para valorar el tratamiento, en este sentido la RPC es una herramienta que puede apoyar a otras pruebas de diagnóstico.

An unusual case of a 3-year-old girl with a brucellar foot abscess is reported. Although direct microscopic examination of samples from the lesion did not reveal micro-organisms of any kind, a 7 day culture of caseous material yielded small colonies of Gram-negative cocobacilli in Löwenstein–Jensen medium. These were biochemically and molecularly identified as Brucella melitensis. The possibility of foot abscess being caused by Brucella should be considered in countries where brucellosis is endemic.

Human brucellosis diagnosis is based on isolation of Brucella spp. from blood or tissue cultures with a positivity rate of 40-70% and serology techniques are used as complementary tools; recently molecular biology diagnostic techniques have been developed intending to optimize the etiological confirmation.The main objective of this work was to compare the polymerase chain reaction (PCR), against serological diagnostic tests during the clinical follow-up of a family presenting brucellosis.Seven family members who lived in the urban area of Mexico City, were monitored using the Rose Bengal test, the agglutination test as well as agglutination with 2 mecapto ethanol, blood cultures and serum PCR for a period of 27 months. The suspected source of infection was fresh goat cheese from a known endemic zone.Brucella melitensis was isolated from the blood cultures of two patients. All of the patients were positive in serological and PCR tests at the beginning of this follow-up. At the end of the study, three patients responded well to the treatment and showed negative results in the serological and PCR tests. While two patients with diabetes mellitus type 2, showed positive results in the serological and PCR tests as well as persistent symptoms.Clinical follow-up of patients with brucellosis is of great importance, to properly evaluate the given treatment. In this sense the PCR is a great supporting tool in diagnostic testing.

Outer membrane vesicles (OMVs) from Brucella melitensis and irradiated Brucella neotomae have been shown to be effective vaccines against a B. melitensis challenge in a mouse model. The present study evaluates the efficacy of these two vaccines as immuno-therapeutics in combination with conventional antibiotics against a B. melitensis infection. BALB/c mice chronically infected with B. melitensis were treated for 4 weeks with doxycycline and gentamicin and vaccinated twice during the course of therapy. Antibiotics in sub-therapeutic concentrations were chosen in such a way that the treatment would result in a therapeutic failure in mice. Although no additive effect of vaccines and antibiotics was seen on the clearance of B. melitensis, mice receiving vaccines along with antibiotics exhibited no Brucella replication post-treatment compared to mice treated only with antibiotics. Administration of irradiated B. neotomae along with antibiotics led to higher production of IFN-γ ex vivo by splenocytes upon stimulation with heat inactivated B. melitensis while no such effect was seen by splenocytes from mice vaccinated with OMVs. OMV vaccinated mice developed significantly higher anti-Brucella IgG antibody titers at the end of the treatment compared to the mice that received only antibiotics. The mice that received only vaccines did not show any significant clearance of Brucella from spleens and livers compared to non-treated control mice. This study suggests that incorporating OMVs or irradiated B. neotomae along with conventional antibiotics might be able to improve therapeutic efficacy and control the progression of disease in treatment failure cases.

Brucellosis is the most common zoonotic disease worldwide, and there is no vaccine for human use. Brucella melitensis Rev1, a live attenuated strain, is the commercial vaccine for small ruminants to prevent B. melitensis infections but has been associated with abortions in animals. Moreover, strain Rev1 is known to cause disease in humans and cannot be used for human vaccination. Outer membrane vesicles (OMVs) obtained from B. melitensis have been shown to provide protection similar to strain Rev1 in mice against B. melitensis challenge. In the present work, we tested the efficacy of Pluronic P85 as an adjuvant to enhance the efficacy of Brucella OMVs as a vaccine. P85 enhanced the in vitro secretion of TNF-α by macrophages induced with OMVs and P85. Further, P85 enhanced the protection provided by OMVs against B. melitensis challenge. This enhanced protection was associated with higher total IgG antibody production but not increased IFN-γ or IL-4 cytokine levels. Moreover, P85 alone provided significantly better clearance of B. melitensis compared to saline-vaccinated mice. Further studies are warranted to find the mechanism of action of P85 that provides nonspecific protection and enhances the efficacy of OMVs as a vaccine against B. melitensis.

The typing of 153 Brucella strains isolated from different regions of Mexico was performed by multiplex PCR Bruce-Ladder. Results showed that microbiological typing and multiplex Bruce-ladder amplification were identical for all Brucella isolates tested. Because of its speed, Bruce-Ladder PCR is a useful method in the typing of Brucella species isolated from animal and humans. Key words: Brucella, brucellosis, typing, Mexico, Bruce-ladder polymerase chain reaction (PCR).

The outer membrane vesicles (OMVs) from smoothB. melitensis16 M and a derived rough mutant, VTRM1 strain, were purified and characterized with respect to protein content and induction of immune responses in mice. Proteomic analysis showed 29 proteins present in OMVs fromB. melitensis16 M; some of them are well-knownBrucellaimmunogens such as SOD, GroES, Omp31, Omp25, Omp19, bp26, and Omp16. OMVs from a rough VTRM1 induced significantly higher expression of IL-12, TNFα, and IFNγ genes in bone marrow dendritic cells than OMVs from smooth strain 16 M. Relative to saline control group, mice immunized intramuscularly with rough and smooth OMVs were protected from challenge with virulent strainB. melitensis16 M just as well as the group immunized with live strainB. melitensisRev1 (P<0.005). Additionally, the levels of serum IgG2a increased in mice vaccinated with OMVs from rough strain VTRM1 consistent with the induction of cell-mediated immunity.

Brucellosis is a disease of domestic and wild animals that is transmitted to humans and exists worldwide. We assessed the in vitro activity of moxifloxacin, ciprofloxacin, tetracycline, doxicycline, rifampin, streptomycin and trimethoprim-sulfamethoxazole (TMP/SMX) against 97 Brucella strains isolated from clinical samples, animals and dairy products in Mexico. Fluoroquinolones showed an antibacterial activity similar to that of tetracyclines (MIC(90) 0.5). Other drugs commonly used against brucellosis were less active, such as rifampin (MIC(90) 2.0 microg/ml) and streptomycin (MIC(90) 4.0 microg/ml). TMP/SMX showed the poorest activity (MIC(90) 8.0 microg/ml). Fluoroquinolones, either first-generation or the newer 8-methoxi derivatives, might be useful in the therapy of brucellosis, which remains to be assessed in clinical trials.

Background The sequenced genomes of the Brucella spp. have two urease operons, ure-1 and ure-2, but there is evidence that only one is responsible for encoding an active urease. The present work describes the purification and the enzymatic and phylogenomic characterization of urease from Brucella suis strain 1330. Additionally, the urease reactivity of sera from patients diagnosed with brucellosis was examined. Results Urease encoded by the ure-1 operon of Brucella suis strain 1330 was purified to homogeneity using ion exchange and hydrophobic interaction chromatographies. The urease was purified 51-fold with a recovery of 12% of the enzyme activity and 0.24% of the total protein. The enzyme had an isoelectric point of 5, and showed optimal activity at pH 7.0 and 28–35°C. The purified enzyme exhibited a Michaelis-Menten saturation kinetics with a K m of 5.60 ± 0.69 mM. Hydroxyurea and thiourea are competitive inhibitors of the enzyme with Ki of 1.04 ± 0.31 mM and 26.12 ± 2.30 mM, respectively. Acetohydroxamic acid also inhibits the enzyme in a competitive way. The molecular weight estimated for the native enzyme was between 130–135 kDa by gel filtration chromatography and 157 ± 7 kDa using 5–10% polyacrylamide gradient non-denaturing gel. Only three subunits in SDS-PAGE were identified: two small subunits of 14,000 Da and 15,500 Da, and a major subunit of 66,000 Da. The amino terminal sequence of the purified large subunit corresponded to the predicted amino acid sequence encoded by ureC1. The UreC1 subunit was recognized by sera from patients with acute and chronic brucellosis. By phylogenetic and cluster structure analyses, ureC1 was related to the ureC typically present in the Rhizobiales; in contrast, the ureC2 encoded in the ure-2 operon is more related to distant species. Conclusion We have for the first time purified and characterized an active urease from B. suis. The enzyme was characterized at the kinetic, immunological and phylogenetic levels. Our results confirm that the active urease of B. suis is a product of ure-1 operon.