Epidemiological role of birds in the transmission and maintenance of zoonoses. / Papel epidemiológico de las aves en la transmisión y mantenimiento de zoonosis.

The risk of zoonoses spreading from birds to humans is lower, quantitatively speaking, than the risk of transmission between other host groups, because the two taxonomic groups share fewer pathogens. Nevertheless, birds have a number of epidemiological characteristics that make them extremely important hosts in the transmission and maintenance of zoonoses, including their susceptibility to pathogens that are extremely hazardous to humans (such as highly pathogenic avian influenza virus, West Nile virus and Chlamydia psittaci) and their ability to travel long distances, especially in the case of migratory birds. The fact that the human diet includes poultry products (meat, eggs and their by-products) also means that most human cases of foodborne zoonoses are infections of avian origin. Lastly, close contact between humans and pet birds or urban birds leads to interactions of public health concern. This article sets out to describe the main factors that determine the role of birds in the epidemiology of zoonotic infections.

Le risque que les oiseaux transmettent des zoonoses à l'homme est moins élevé, au plan quantitatif, qu'entre hôtes d'autres catégories, car le nombre d'agents pathogènes affectant à la fois ces deux groupes taxonomiques est moindre. Cependant, certaines particularités épidémiologiques des oiseaux leur font jouer un rôle d'hôtes importants dans la persistance et la transmission de zoonoses : d'une part, leur sensibilité à des agents pathogènes dangereux pour l'homme (par exemple, le virus de l'influenza aviaire hautement pathogène, le virus de West Nile, Chlamydia psittaci) et, d'autre part, leur capacité à se déplacer sur de longues distances, notamment dans le cas des oiseaux migrateurs. En outre, les produits avicoles faisant partie des denrées alimentaires consommées par l'homme (viande de volaille, oeufs et produits dérivés), la majorité des cas de zoonoses d'origine alimentaire diagnostiqués chez l'homme sont d'origine aviaire. Enfin, les contacts étroits entre les humains et leurs oiseaux de compagnie ou avec des oiseaux des villes entraînent des interactions qui sont à prendre en compte en santé publique. Les auteurs décrivent les principales caractéristiques épidémiologiques des oiseaux jugées déterminantes par rapport aux infections zoonotiques.

El riesgo de transmisión de zoonosis de aves a humanos es menor, cuantitativamente hablando, que el que tiene lugar entre otros grupos de hospedadores, debido a que estos dos grupos taxonómicos comparten un menor número de agentes patógenos. No obstante, algunas particularidades epidemiológicas de las aves las convierten en hospedadores de gran importancia en el mantenimiento y la transmisión de zoonosis, como su capacidad de contraer infecciones por agentes patógenos peligrosos para los humanos (como el virus de la influenza aviar altamente patógena, el virus del Nilo Occidental o Chlamydia psittaci, entre otros) así como su gran capacidad de desplazamiento, especialmente en el caso de las aves migratorias. Además, el hecho de que la alimentación humana incluya productos avícolas (carne y huevos y productos derivados) hace que la mayoría de casos de zoonosis de origen alimentario diagnosticados en humanos sean infecciones de origen aviar. Por último, el estrecho contacto entre humanos y mascotas aviares o aves urbanas conlleva interacciones de interés para la salud pública. Este trabajo pretende describir los principales determinantes epidemiológicos de las aves en relación con las infecciones zoonósicas.

Sensitivity of two methods to detect Mycoplasma agalactiae in goat milk.

BACKGROUND: Laboratory diagnostic techniques able to detect Mycoplasma agalactiae are essential in contagious agalactia in dairy goats. This study was designed: 1) to determine the detection limits of PCR and culture in goat milk samples, 2) to examine the effects of experimental conditions including the DNA extraction method, PCR technique and storage conditions (fresh versus frozen stored milk samples) on these methods and 3), to establish agreement between PCR and culture techniques using milk samples from goats with mastitis in commercial dairy herds. The study was conducted both on artificially inoculated and field samples. RESULTS: Our findings indicate that culture is able to detect M. agalactiae in goat milk at lower concentrations than PCR. Qualitative detection of M.agalactiae by culture and PCR was not affected by sample freezing, though the DNA extraction method used significantly affected the results of the different PCR protocols. When clinical samples were used, both techniques showed good agreement. CONCLUSIONS: The results from this study indicate that both culture and PCR are able to detect M. agalactiae in clinical goat mastitis samples. However, in bulk tank milk samples with presumably lower M. agalactiae concentrations, culture is recommended within the first 24 h of sample collection due to its lower limit of detection. To improve the diagnostic sensitivity of PCR in milk samples, there is a need to increase the efficiency of extracting DNA from milk samples using protocols including a previous step of enzymatic digestion.

Understanding acute metabolic decompensation in propionic and methylmalonic acidemias: a deep metabolic phenotyping approach.

BACKGROUND: Pathophysiology of life-threatening acute metabolic decompensations (AMD) in propionic acidemia (PA) and isolated methylmalonic acidemia (MMA) is insufficiently understood. Here, we study the metabolomes of PA and MMA patients over time, to improve insight in which biochemical processes are at play during AMD. METHODS: Longitudinal data from clinical chemistry analyses and metabolic assays over the life-course of 11 PA and 13 MMA patients were studied retrospectively. Direct-infusion high-resolution mass spectrometry was performed on 234 and 154 remnant dried blood spot and plasma samples of PA and MMA patients, respectively. In addition, a systematic literature search was performed on reported biomarkers. All results were integrated in an assessment of biochemical processes at play during AMD. RESULTS: We confirmed many of the metabolite alterations reported in literature, including increases of plasma valine and isoleucine during AMD in PA patients. We revealed that plasma leucine and phenylalanine, and urinary pyruvic acid were increased during AMD in PA patients. 3-hydroxyisovaleric acid correlated positively with plasma ammonia. We found that known diagnostic biomarkers were not significantly further increased, while intermediates of the branched-chain amino acid (BCAA) degradation pathway were significantly increased during AMD. CONCLUSIONS: We revealed that during AMD in PA and MMA, BCAA and BCAA intermediates accumulate, while known diagnostic biomarkers remain essentially unaltered. This implies that these acidic BCAA intermediates are responsible for metabolic acidosis. Based on this, we suggest to measure plasma 3-hydroxyisovaleric acid and urinary ketones or 3-hydroxybutyric acid for the biochemical follow-up of a patient's metabolic stability.

The moderate drift towards less tetracycline-susceptible isolates of contagious agalactia causative agents might result from different molecular mechanisms.

Contagious agalactia is a mycoplasmosis that affects small ruminants, is associated with loss of milk production and high morbidity rates, and is highly deleterious to dairy industries. The etiological agents are four mycoplasma (sub)species, of which the relative importance depends on the countries and the animal host. Tetracyclines are non-expensive, broad-spectrum antimicrobials and are often used to control mastitis in dairy herds. However, the in vitro efficiency of tetracyclines against each of the etiological agents of contagious agalactia has been poorly assessed. The aims of this study were i) to compare the tetracycline susceptibilities of various field isolates, belonging to different mycoplasma (sub)species and subtypes, collected over the years from different clinical contexts in France or Spain, and ii) to investigate the molecular mechanisms behind the decreased susceptibility of some isolates to tetracyclines. The Minimum Inhibitory Concentrations (MICs) of tetracyclines were determined in vitro on a set of 120 isolates. Statistical analyses were run to define the significance of any observed differences in MICs distribution. As mutations in the genes encoding the tetracycline targets (rrs loci) are most often associated with increased tetracycline MICs in animal mycoplasmas, these genes were sequenced. The loss of susceptibility to tetracyclines after year 2010 is not significant and recent MICs are higher in M. agalactiae, especially isolates from mastitis cases, than in other etiological agents of contagious agalactia. The observed increases in MICs were not always associated with mutations in the rrs alleles which suggests the existence of other resistance mechanisms yet to be deciphered.

Saline is as effective as nitrogen scavengers for treatment of hyperammonemia.

Urea cycle enzyme deficiency (UCED) patients with hyperammonemia are treated with sodium benzoate (SB) and sodium phenylacetate (SPA) to induce alternative pathways of nitrogen excretion. The suggested guidelines supporting their use in the management of hyperammonemia are primarily based on non-analytic studies such as case reports and case series. Canine congenital portosystemic shunting (CPSS) is a naturally occurring model for hyperammonemia. Here, we performed cross-over, randomized, placebo-controlled studies in healthy dogs to assess safety and pharmacokinetics of SB and SPA (phase I). As follow-up safety and efficacy of SB was evaluated in CPSS-dogs with hyperammonemia (phase II). Pharmacokinetics of SB and SPA were comparable to those reported in humans. Treatment with SB and SPA was safe and both nitrogen scavengers were converted into their respective metabolites hippuric acid and phenylacetylglutamine or phenylacetylglycine, with a preference for phenylacetylglycine. In CPSS-dogs, treatment with SB resulted in the same effect on plasma ammonia as the control treatment (i.e. saline infusion) suggesting that the decrease is a result of volume expansion and/or forced diuresis rather than increased production of nitrogenous waste. Consequentially, treatment of hyperammonemia justifies additional/placebo-controlled trials in human medicine.

In vitro assessment of the antimicrobial susceptibility of caprine isolates of Mycoplasma mycoides subsp. capri.

The minimum inhibitory concentration (MIC) and minimum mycoplasmacidal concentration (MMC) of 17 antimicrobials against 41 Spanish caprine isolates of Mycoplasma mycoides subsp. capri (Mmc) obtained from different specimens (milk, external auricular canal and semen) were determined using a liquid microdilution method. For half of the isolates, the MIC was also estimated for seven of the antimicrobials using an epsilometric test (ET), in order to compare both methods and assess the validity of ET. Mutations in genes gyrA, gyrB, parC and parE conferring fluoroquinolone resistance, which have been recently described in Mmc, were investigated using PCR. The anatomical origin of the isolate had no effect on its antimicrobial susceptibility. Moxifloxacin and doxycycline had the lowest MIC values. The rest of the fluoroquinolones studied (except norfloxacin), together with tylosin and clindamycin, also had low MIC values, although the MMC obtained for clindamycin was higher than for the other antimicrobials. For all the aminoglycosides, spiramycin and erythromycin, a notable level of resistance was observed. The ET was in close agreement with broth microdilution at low MICs, but not at intermediate or high MICs. The analysis of the genomic sequences revealed the presence of an amino acid substitution in codon 83 of the gene gyrA, which has not been described previously in Mmc.

The use of frozen-stored sheep erythrocytes for demonstrating lymphocytic membrane markers.

The usefulness of cryopreserved sheep erythrocytes (unsensitized or coated with fluorescein, IgG-type antibody or complement) for marker tests on human blood lymphocytes was studied. It appears that the rosetting properties or freshly prepared or frozen-stored erythrocytes are not significantly different. The method may be used to provide homogeneous stocks of sensitized erythrocytes for lymphocyte rosetting technique.

Quantification of vitamin B6 vitamers in human cerebrospinal fluid by ultra performance liquid chromatography-tandem mass spectrometry.

Since vitamin B6 is essential for normal functioning of the central nervous system, there is growing need for sensitive analysis of B6 vitamers in cerebrospinal fluid (CSF). This manuscript describes the development and validation of a rapid, sensitive and accurate method for quantification of the vitamin B6 vitamers pyridoxal (PL), pyridoxamine (PM), pyridoxine (PN), pyridoxic acid (PA), pyridoxal 5'-phosphate (PLP), pyridoxamine 5'-phosphate (PMP) and pyridoxine 5'-phosphate (PNP) in human CSF. The method is based on ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with a simple sample preparation procedure of protein precipitation using 50 g L(-1) trichloroacetic acid containing stable isotope labeled internal standards: PL-D(3) for PL and PM, PN-(13)C(4) for PN, PA-D(2) for PA and PLP-D(3) for the phosphorylated vitamers. B6 vitamers were separated (Acquity HSS-T3 UPLC column) with a buffer containing acetic acid, heptafluorobutyric acid and acetonitrile. Positive electrospray ionization was used to monitor transitions m/z 168.1→150.1 (PL), 169.1→134.1 (PM), 170.1→134.1 (PN), 184.1→148.1 (PA), 248.1→150.1 (PLP), 249.1→232.1 (PMP) and 250.1→134.1 (PNP). The method was validated at three concentration levels for each B6 vitamer in CSF. Recoveries of the internal standards were between 93% and 96%. Intra- and inter-assay variations were below 20%. Accuracy tests showed deviations from 3% (PN) to 39% (PMP). Limits of quantification were in the range of 0.03-5.37 nM. Poor results were obtained for quantification of PNP. The method was applied to CSF samples of 20 subjects and two patients on pyridoxine supplementation. Using minimal CSF volumes this method is suitable for implementation in a routine diagnostic setting.

The influence of bile acids on the oral bioavailability of vitamin K encapsulated in polymeric micelles.

The purpose of this study was to assess the ability of polymeric micelles to enable gastrointestinal absorption of the extremely hydrophobic compound vitamin K, by comparison of its absorption in bile duct ligated and sham operated rats. Hereto, vitamin K was encapsulated in micelles composed of mPEG(5000)-b-p(HPMAm-lac(2)), a thermosensitive block copolymer. Vitamin K plasma levels rose significantly upon gastric administration of 1 mg vitamin K encapsulated in polymeric micelles in sham operated rats, but not after bile duct ligation (AUC 4543 and 1.64 ng/mL/h respectively, p<0.01). Duodenal administration of polymeric micelles together with bile acids in bile duct ligated rats fully restored absorption. Dynamic light scattering time series showed a significant and dose dependent rise in micellar size in the presence of bile acids in vitro, indicating the gradual formation of mixed micelles during the first 3 h of incubation. The highest bile acid amounts (11 mM deoxycholic acid and 41 mM taurocholic acid) eventually caused aggregation of the loaded micelles after the formation of mixed micelles. These data suggest that the gastrointestinal absorption of encapsulated vitamin K from polymeric micelles is mediated by free bile and that uptake of intact micelles through pinocytosis is insignificant.

Binding of IgM by human T lymphocytes.

Ox erythrocytes, sensitized with IgM-type rabbit antibodies, were found to form rosettes with human blood lymphocytes. Granulocytes, monocytes, and macrophages appeared to lack this property. The rosette formation could be inhibited with human IgM and its Fc fragments. IgM-binding lymphocytes were also present in cell suspensions isolated from human tonsils and thymuses and among blood lymphocytes cultured in vitro. The outcome of combined marker tests and cell separation experiments disclosed that the rosetting lymphocytes belong to the T-lymphocyte population.

Diminished antibiotic sensitivity of Neisseria gonorrhoeae in urban and rural areas in Kenya.

PIP: A total of 1730 cases of suspected gonorrhea were investigated in 8 urban and rural clinics in Kenya; sensitivity tests were performed in 736 cases. A majority of the strains had relative resistance to 2 drugs in common use--penicillin and streptomycin. For tetracycline, a slightly decreased sensitivity was often found and resistance to these antibiotics was usually linked. It was found that relative resistance to antibiotics is already common in rural areas in which the majority of the African population live, and that resistance to penicillin is even more common in rural areas than towns. Evidence that this may result from the continuation of inadequate treatment, especially in developing tropical countries was obtained. Such countries are becoming an immense reservoir of strains with a high level of resistance to penicillin. Ways of remedying this situation are discussed. (author's modified)^ieng