A Set of Multiresistant Isolates of Mycoplasma bovis Subtype ST-1 with a Variable Susceptibility to Quinolones Are Also Circulating in Spain.

Mycoplasma bovis (M. bovis) is one of the worldwide most important infectious agents involved in respiratory complex diseases (RCD). In Spain, the endemic presence of subtypes ST-2 and ST-3 with phenotypic differences linked to their susceptibility to fluoroquinolones opened the way to develop control strategies focused on previous diagnosis of the subtype and the use of directed therapies when M. bovis were involved in RCD. Surprisingly, microbiological studies conducted during 2023 evidenced for the first time the presence of Spanish isolates of a new polC-subtype, previously classified as ST-1, recovered from calves with respiratory symptoms and pneumonia in different areas of the country (n = 16). Curiously, the minimum inhibitory concentration (MIC) to a panel of antimicrobials revealed phenotypic differences between these ST-1 isolates when using fluoroquinolones (FLQ). There is no geographical correlation between MIC profiles even for a set of 8 isolates recovered from different animals in the same flock. Sequencing of 4 genes (gyrA, gyrB, parC and parE) encoding quinolone resistance-determining regions (QRDR) evidenced the presence of accumulate mutations in 2 ST-1 isolates with high FLQ MICs, but not in all them (n = 3), thus suggesting that, as previously recorded for ST-2 isolates, other mechanisms should be involved in the acquisition of resistence to these antimicrobials. Additionally, as previously detected in the Spanish ST-2 and ST-3, subtype ST-1 isolates are also resistant to macrolides or lincosamides.

Antibacterial potential of commercial and wild lactic acid bacteria strains isolated from ovine and caprine raw milk against Mycoplasma agalactiae.

Introduction: The complexity of fighting contagious agalactia (CA) has raised the necessity of alternative antimicrobial therapies, such as probiotics. Lactic acid bacteria (LAB) are present in the mammary gland of small ruminants and their antimicrobial effect have been previously described against species like Mycoplasma bovis but never against Mycoplasma agalactiae (Ma). This in vitro study aims to evaluate the antimicrobial activity against Ma of ovine and caprine LAB strains and a human commercial probiotic (L2) of Lactobacillus spp. Methods: A total of 63 possible LAB strains were isolated from nine ovine and caprine farms in Spain, three isolates (33B, 248D, and 120B) from the 63 strains were selected, based on their capacity to grow in a specific medium in vitro, for an in vitro experiment to assess their antimicrobial activity against Ma in Ultra High Temperature (UHT) processed goat milk (GM). A women commercial vaginal probiotic was also included in the study. The inoculum of L2 was prepared at a concentration of 3.24 × 108 CFU/mL and the average concentration of the inoculum of the wild LAB varied from 7.9 × 107 to 8.4 × 108 CFU/mL. Results: The commercial probiotic L2 significantly reduced the concentration of Ma to 0.000 log CFU/mL (p < 0.001), strain 33B reduced it from 7.185 to 1.279 log CFU/mL (p < 0.001), and 120B from 6.825 to 6.466 log CFU/mL (p < 0.05). Strain 248D presented a bacteriostatic effect in GM. Moreover, the three wild strains and the commercial probiotic produced a significative reduction of the pH (p < 0.001). Discussion: This is the first in vivo report of the antimicrobial potential of LAB strains against Ma and its interaction. Our results support possible future alternative strategies to antibiotic therapy, previously not contemplated, to fight CA in small ruminants. Further studies are necessary to elucidate the action mechanisms through which these LAB are able to inhibit Ma and to assess the safety of using these strains in possible in vivo studies.

RustOnt: An Ontology to Explain Weather Favorable Conditions of the Coffee Rust.

Crop disease management in smart agriculture involves applying and using new technologies to reduce the impact of diseases on the quality of products. Coffee rust is a disease that factors such as poor agronomic management activities and climate conditions may favor. Therefore, it is crucial to identify the relationships between these factors and this disease to learn how to face its consequences and build intelligent systems to provide appropriate management or help farmers and experts make decisions accordingly. Nevertheless, there are no studies in the literature that propose ontologies to model these factors and coffee rust. This paper presents a new ontology called RustOnt to help experts more accurately model data, expressions, and samples related to coffee rust and apply it whilst taking into account the geographical location where the ontology is adopted. Consequently, this ontology is crucial for coffee rust monitoring and management by means of smart agriculture systems. RustOnt was successfully evaluated considering quality criteria such as clarity, consistency, modularity, and competence against a set of initial requirements for which it was built.

Susceptibility of caprine mastitis pathogens to tildipirosin, gamithromycin, oxytetracycline, and danofloxacin: effect of serum on the in vitro potency of current macrolides.

Mastitis is a significant disease in dairy ruminants, causing economic losses to the livestock industry and severe risks to public health. Antibiotic therapy is one of the most crucial practices to treat mastitis, although the susceptibility of caprine mastitis pathogens to current antibiotics has not been tested under standard or modified incubation conditions. This work evaluated the in vitro activity of tildipirosin, gamithromycin, oxytetracycline, and danofloxacin against caprine mastitis pathogens incubated following standard conditions of Clinical and Laboratory Standards Institute (CLSI) and deviation method by 25% supplementation with goat serum. Mycoplasma agalactiae, Escherichia coli, Staphylococcus aureus, Streptococcus spp., and coagulase-negative Staphylococci (CNS) were isolated from dairy goats with mastitis in Spain. Minimum inhibitory concentrations (MICs) were determined using the broth microdilution technique. The lowest MIC90 under standard conditions was obtained with danofloxacin for mastitis-causing pathogens. An exception was M. agalactiae, where danofloxacin and oxytetracycline obtained low values. However, after adding serum, gamithromycin showed the lowest MIC50 for S. aureus, Streptococcus spp., and CNS. The lowest MIC50 was obtained with all the antibiotics tested (< 0.125 µg/ml) against M. agalactiae. Supplementing with serum resulted in a significant variation in tildipirosin and gamithromycin MIC values for CNS, S. aureus, M. agalagtiae, and E. coli. In brief, the MIC for antibiotics used against mastitis should be determined under conditions closely resembling intramammary infections to obtain representative susceptibility patterns against mastitis pathogens. Caprine mastitis pathogens were broadly susceptible to danofloxacin under standard conditions. The potency of macrolides against caprine mastitis pathogens increases when serum is present in culture media.

An Adaptive Sampling Period Approach for Management of IoT Energy Consumption: Case Study Approach.

The Internet of Things (IoT) opens opportunities to monitor, optimize, and automate processes into the Agricultural Value Chains (AVC). However, challenges remain in terms of energy consumption. In this paper, we assessed the impact of environmental variables in AVC based on the most influential variables. We developed an adaptive sampling period method to save IoT device energy and to maintain the ideal sensing quality based on these variables, particularly for temperature and humidity monitoring. The evaluation on real scenarios (Coffee Crop) shows that the suggested adaptive algorithm can reduce the current consumption up to 11% compared with a traditional fixed-rate approach, while preserving the accuracy of the data.

Blockchain-IoT Sensor (BIoTS): A Solution to IoT-Ecosystems Security Issues.

Sensor devices that act in the IoT architecture perception layer are characterized by low data processing and storage capacity. These reduced capabilities make the system ubiquitous and lightweight, but considerably reduce its security. The IoT-based Food Traceability Systems (FTS), aimed at ensuring food safety and quality, serve as a motivating scenario for BIoTS development and deployment; therefore, security challenges and gaps related with data integrity are analyzed from this perspective. This paper proposes the BIoTS hardware design that contains some modules built-in VHDL (SHA-256, PoW, and SD-Memory) and other peripheral electronic devices to provide capabilities to the perception layer by implementing the blockchain architecture's security requirements in an IoT device. The proposed hardware is implemented on FPGA Altera DE0-Nano. BIoTS can participate as a miner in the blockchain network through Smart Contracts and solve security issues related to data integrity and data traceability in an Blockchain-IoT system. Blockchain algorithms implemented in IoT hardware opens a path to IoT devices' security and ensures participation in data validation inside a food certification process.

Antibody seropositivity for Neospora caninum in Blanco Orejinegro cattle in Colombia and factors associated with the infection.

Neosporosis is a parasitic disease that causes abortions and economic losses in bovine production systems, but no studies have been found concerning its effect on the Creole cattle breed, Blanco Orejinegro (BON). The aim of this research was to establish the serological status of Colombian BON cattle against Neospora caninum and to determine the factors associated with seropositivity. Blood samples were taken from 363 animals from 13 herds in six states of Colombia, and analyzed by indirect ELISA using a commercial test. Information on sex, herd, generation group, and state was recorded. A survey was carried out with 26 questions related to productive, reproductive, and health factors per herd. A logistic regression analysis was performed and the ORs for significantly associated variables were estimated using the R software. General seropositivity of 73.5% (95% CI 68.6-77.9%) was obtained, and sex, age group, and herd were the variables significantly associated with seropositivity (p < 0.05). For the sex variable, seroprevalence levels of 79.6% (95% CI 74.3-84.1%) were recorded for females and 54.5% (95% CI 43.6-65.1%) for males. Herd seroprevalence varied between 58.3 and 95.8%, and the last generation showed the lowest positivity (51.2%, 95% CI 42.1-60.2%). The inadequate disposal of fetuses was a risk factor, while carrying out serological tests to new animals that enter the herd, the use of new gloves and palpation utensils for each animal, supplementation, and stabling were stated as protective factors. No effect of positivity was found in the last calving interval. The implementation of bovine neosporosis control programs to support breeding and conservation programs of the BON breed in Colombia is recommended.

[Mechanical ventilator test protocol for care of patients with COVID-19 in porcine model]. / Protocolo de prueba de ventilador mecánico para atención de pacientes con COVID-19 en modelo porcino.

As a result of the SARS-CoV-2 pandemic, health systems globally have seen a dramatic increase in the occupancy of intensive care units, with mechanical ventilators being a resource in high demand in the care of these patients. This article proposes a protocol for testing low-cost mechanical ventilators in pig models, as part of the development of locally manufactured biomedical equipment that can support the health crisis caused by the pandemic. The protocol addresses aspects that include the pre-test phase, anesthetic and airway management, laboratory monitoring, recovery and monitoring of the animal. This document presents to the academic community a validation protocol of a mechanical ventilator prototype in a pig specimen that can be a reference for its application and revalidation by other groups interested in the development of local and low-cost technologies.

A raíz de la pandemia generada por el SARS-CoV-2, los sistemas de salud de los distintos países han experimentado un dramático aumento en la ocupación de las unidades de cuidado intensivo y, por ende, una alta demanda de ventiladores mecánicos. En este artículo se propone un protocolo de pruebas de ventiladores mecánicos de bajo costo en modelos porcinos, como parte del desarrollo de equipos biomédicos que pueden apoyar la crisis sanitaria suscitada por la pandemia. El protocolo aborda aspectos que incluyen la fase previa a la prueba, el manejo anestésico, de vía aérea, seguimiento de laboratorio, recuperación y seguimiento del animal. Como resultado, se presenta a la comunidad académica un protocolo de validación de prototipo de ventilador mecánico en espécimen porcino como un referente para su aplicación y revalidación por parte de grupos interesados en el desarrollo de tecnologías locales de bajo costo.

Protocolo de prueba de ventilador mecánico para atención de pacientes con COVID-19 en modelo porcino / Mechanical ventilator test protocol for care of patients with COVID-19 in porcine model

RESUMEN A raíz de la pandemia generada por el SARS-CoV-2, los sistemas de salud de los distintos países han experimentado un dramático aumento en la ocupación de las unidades de cuidado intensivo y, por ende, una alta demanda de ventiladores mecánicos. En este artículo se propone un protocolo de pruebas de ventiladores mecánicos de bajo costo en modelos porcinos, como parte del desarrollo de equipos biomédicos que pueden apoyar la crisis sanitaria suscitada por la pandemia. El protocolo aborda aspectos que incluyen la fase previa a la prueba, el manejo anestésico, de vía aérea, seguimiento de laboratorio, recuperación y seguimiento del animal. Como resultado, se presenta a la comunidad académica un protocolo de validación de prototipo de ventilador mecánico en espécimen porcino como un referente para su aplicación y revalidación por parte de grupos interesados en el desarrollo de tecnologías locales de bajo costo.

ABSTRACT As a result of the SARS-CoV-2 pandemic, health systems globally have seen a dramatic increase in the occupancy of intensive care units, with mechanical ventilators being a resource in high demand in the care of these patients. This article proposes a protocol for testing low-cost mechanical ventilators in pig models, as part of the development of locally manufactured biomedical equipment that can support the health crisis caused by the pandemic. The protocol addresses aspects that include the pre-test phase, anesthetic and airway management, laboratory monitoring, recovery and monitoring of the animal. This document presents to the academic community a validation protocol of a mechanical ventilator prototype in a pig specimen that can be a reference for its application and revalidation by other groups interested in the development of local and low-cost technologies.

Protocolo de prueba de ventilador mecánico para atención de pacientes con COVID-19 en modelo porcino / Mechanical ventilator test protocol for care of patients with COVID-19 in porcine model

RESUMEN A raíz de la pandemia generada por el SARS-CoV-2, los sistemas de salud de los distintos países han experimentado un dramático aumento en la ocupación de las unidades de cuidado intensivo y, por ende, una alta demanda de ventiladores mecánicos. En este artículo se propone un protocolo de pruebas de ventiladores mecánicos de bajo costo en modelos porcinos, como parte del desarrollo de equipos biomédicos que pueden apoyar la crisis sanitaria suscitada por la pandemia. El protocolo aborda aspectos que incluyen la fase previa a la prueba, el manejo anestésico, de vía aérea, seguimiento de laboratorio, recuperación y seguimiento del animal. Como resultado, se presenta a la comunidad académica un protocolo de validación de prototipo de ventilador mecánico en espécimen porcino como un referente para su aplicación y revalidación por parte de grupos interesados en el desarrollo de tecnologías locales de bajo costo.

ABSTRACT As a result of the SARS-CoV-2 pandemic, health systems globally have seen a dramatic increase in the occupancy of intensive care units, with mechanical ventilators being a resource in high demand in the care of these patients. This article proposes a protocol for testing low-cost mechanical ventilators in pig models, as part of the development of locally manufactured biomedical equipment that can support the health crisis caused by the pandemic. The protocol addresses aspects that include the pre-test phase, anesthetic and airway management, laboratory monitoring, recovery and monitoring of the animal. This document presents to the academic community a validation protocol of a mechanical ventilator prototype in a pig specimen that can be a reference for its application and revalidation by other groups interested in the development of local and low-cost technologies.

23S rRNA and L22 ribosomal protein are involved in the acquisition of macrolide and lincosamide resistance in Mycoplasma capricolum subsp. capricolum.

Mycoplasma capricolum subsp. capricolum (Mcc) is one of the causative agents of contagious agalactia, and antimicrobial therapy is the most commonly applied measure to treat outbreaks of this disease. Macrolides and lincosamides bind specifically to nucleotides at domains II and V of the 23S rRNA. Furthermore, rplD and rplV genes encode ribosomal proteins L4 and L22, which are also implicated in the macrolide binding site. The aim of this work was to study the relationship between mutations in these genes and the acquisition of macrolide and lincosamide resistance in Mcc. For this purpose, in vitro selected resistant mutants and field isolates were studied. This study demonstrates the appearance of DNA point mutations at the 23S rRNA encoding genes (A2058G, A2059G and A2062C) and rplV gene (Ala89Asp) in association to high minimum inhibitory concentration values. Hence, it proves the importance of alterations in 23S rRNA domain V and ribosomal protein L22 as molecular mechanisms responsible for the acquisition of macrolide and lincosamide resistance in both field isolates and in vitro selected mutants. Moreover, these mutations enable us to provide an interpretative breakpoint of antimicrobial resistance for Mcc at MIC 0.8 µg/ml.

Molecular resistance mechanisms of Mycoplasma agalactiae to macrolides and lincomycin.

The extensive use of antimicrobials for disease control has caused a remarkable decrease in antimicrobial susceptibility of different animal mycoplasma species, including Mycoplasma agalactiae (M. agalactiae), the main causative agent of contagious agalactia. However, the molecular mechanisms behind M. agalactiae resistance to macrolides and lincomycin have not yet been elucidated. The aim of the present study was to investigate the association between minimum inhibitory concentration (MIC) values of different antimicrobials and mutations in the 23S rRNA gene and ribosomal proteins L4 and L22, analysing both field isolates (n=50) and in vitro selected resistant mutants of M. agalactiae. The obtained MIC results of the studied field isolates demonstrate an increasing development of tylosin resistance in this bacterium, in comparison to previous studies. Interestingly, predicted amino acid changes in L22 (Ser89Leu and Gln90Lys/His) were the first variations observed when MICs of M. agalactiae started to increase (tylosin MIC ≥0.8µg/ml), whereas mutations at positions 2058 or 2059 of domain V of the 23S rRNA gene appeared from MIC values of 1.6µg/ml. These results were consistent in both field isolates and in vitro selected mutants of M. agalactiae. Thus, although in other mycoplasma species resistance to macrolides and lincosamides had been mainly related to mutations in the 23S rRNA gene, this work demonstrates the role of alterations in ribosomal protein L22 in decreased susceptibility of M. agalactiae. Moreover, these mutations can be used as molecular markers to set an interpretative breakpoint of antimicrobial resistance for M. agalactiae.

Mutations in the quinolone resistance determining region conferring resistance to fluoroquinolones in Mycoplasma agalactiae.

M. agalactiae is the main causative agent of contagious agalactia, against which antimicrobial treatment is the main applied control measure. Quinolones are an effective group of antimicrobials inhibiting the growth of M. agalactiae, but in the last years, various reports have demonstrated an increase of resistance in field isolates due to its massive use. Nevertheless, the molecular mechanisms involved in the acquisition of fluoroquinolones resistance in M. agalactiae have not been elucidated yet. Therefore, the aim of this work was to analyze the presence of DNA variations that could be related to changes in fluoroquinolone susceptibility. For this purpose, three M. agalactiae strains were selected to obtain in vitro resistant mutants against enrofloxacin, marbofloxacin and moxifloxacin and afterwards, partial sequences of their gyrA, gyrB, parC and parE genes were analyzed. In addition, a set of field isolates with different MIC values were also studied. Changes related to variations in fluoroquinolones susceptibility were found in gyrB, parC and parE. Specifically, gyrB genes were affected at the predicted amino acid position 424, four amino acid changes were detected in parC (positions 78, 79, 80 and 84) and two substitutions were reported in parE (amino acid positions 429 and 459). Mutations at predicted positions 424 of gyrB and 429 of parE are novel DNA changes which had not been previously described and, on the whole, parC was the first gene showing alterations when changes in susceptibility to fluoroquinolones occurred. Thus, this gene is the most suitable target for a rapid study of fluoroquinolone resistance in field isolates of M. agalactiae.

Resistance mechanisms against quinolones in Mycoplasma capricolum subsp. capricolum.

Quinolones interact with bacterial DNA gyrase and topoisomerase IV, the subunits of which are encoded by gyrA/gyrB and parC/parE, respectively. The aim of this study was to evaluate the relationship between changes in these genes and quinolone susceptibility of Mycoplasma capricolum subsp. capricolum (Mcc). Using in vitro selected resistant mutants and field isolates from goats, predicted amino acid changes in gyrA, gyrB and parC were associated with higher minimum inhibitory concentration values for quinolones. Alterations in parC predicted amino acid sequences were most frequently associated with quinolone resistance in Mcc.

Antimicrobial susceptibility and multilocus sequence typing of Mycoplasma capricolum subsp. capricolum.

Mycoplasma capricolum subsp. capricolum is one of the causative agents of contagious agalactia (CA). Nevertheless, there is still a lack of information about its antimicrobial susceptibility and genetic characteristics. Therefore, the aim of this work was to study the antimicrobial and genetic variability of different Mycoplasma capricolum subsp. capricolum field isolates. For this purpose, the growth inhibition effect of 18 antimicrobials and a multilocus sequence typing (MLST) scheme based on five housekeeping genes (fusA, glpQ, gyrB, lepA and rpoB) were performed on 32 selected field isolates from Italy and Spain.The results showed a wide range of growth inhibitory effects for almost all the antimicrobials studied. Macrolides presented lower efficacy inhibiting Mcc growth than in previous works performed on other CA-causative mycoplasmas. Erythromycin was not able to inhibit the growth of any of the studied strains, contrary to doxycycline, which inhibited the growth of all of them from low concentrations. On the other hand, the study of the concatenated genes revealed a high genetic variability among the different Mcc isolates. Hence, these genetic variations were greater than the ones reported in prior works on other mycoplasma species.

Detecting asymptomatic rams infected with Mycoplasma agalactiae in ovine artificial insemination centers.

Mycoplasma agalactiae (Ma) is the main causative agent of ovine contagious agalactia, which is a serious disease of small ruminants. In endemic areas, its most common clinical situation consists of chronically infected herds, and asymptomatic infected individuals represent an epidemiological risk regarding the transmission of this disease. The aim of this work was to detect the presence of asymptomatic rams infected with Ma in different artificial insemination centers, and to determine the most effective way to identify these individuals so as to implement adequate surveillance protocols. For this purpose, 215 rams and 14 teaser sheep were sampled taking auricular, nasal, and vaginal swabs and serum samples. In addition, ejaculates from 147 rams were analyzed. These samples were subjected to specific culture and molecular techniques to isolate and identify mycoplasmas, and to a serological test to detect antibodies against Ma. Mycoplasma agalactiae was detected in 47 (4.4%) of the 1077 samples analyzed, and also one individual resulted seropositive. Thus, 37 (17.2%) of the 215 studied rams were infected with Ma. The specimens which proportionally yielded the greatest number of positive results for this pathogen were semen samples (13.6%), followed by nasal swabs (5.8%). In contrast, the sampling of the external auricular canal and the serological analyses resulted insufficient to effectively detect infected individuals. Asymptomatic rams infected with Ma were detected in all the analyzed artificial insemination centers, highlighting the need to implement adequate surveillance protocols to prevent the presence of these individuals in these centers, reducing the risk of transmitting contagious agalactia.

Multilocus sequence typing of Mycoplasma mycoides subsp. capri to assess its genetic variability in a contagious agalactia endemic area.

Mycoplasma mycoides subsp. capri (Mmc) is one of the main causative agents of caprine contagious agalactia. Besides, the absence of accurate control methods eases its dispersion between different herds within endemic areas of this disease. In this context, there is a need to implement molecular typing schemes which offer valuable information useful to establish control measures and enables the surveillance of this pathogen. The aim of this study was to assess the genetic variability of different strains of Mmc from a contagious agalactia endemic area through multilocus sequence typing (MLST). For this purpose, five house-keeping genes (fusA, glpQ, gyrB, lepA, rpoB) from 39 field isolates were analysed. These isolates were obtained from different geographic areas of Spain, between the years 2004 and 2015. The results obtained in this study suggest that the selected MLST scheme could be a useful technique to monitor the genetic variability of Mmc in endemic areas. Despite the significant differences found between the assessed field isolates, they could be classified according to their geographical origin. Moreover, it was also possible to detect genetic differences between Mmc strains coming from the same herd at the same sampling time, which may need to be taken into consideration when designing or arranging prophylactic strategies.

Leucotoxic activities of Staphylococcus aureus strains isolated from cows, ewes, and goats with mastitis: importance of LukM/LukF'-PV leukotoxin.

Among the toxins that Staphylococcus aureus is able to secrete, bi-component toxins named leukotoxins target specifically leukocytes, mainly phagocytic cells. Isolates from cows, goats and ewes with mastitis were selected on the basis of the presence or not of the genes encoding the recently described LukM/LukF'-PV leukotoxin. Of the 128 isolates tested, 126 had moderate to high leukotoxic activity to bovine polymorphonuclear cells (PMN). The supernatants of lukM-positive isolates were much more leukotoxic than the supernatants of lukM-negative isolates: mean leukotoxic titers were 122 versus 20 and 581 versus 26 for isolates of bovine and caprine origin, respectively. Among lukM/lukF'-PV positive isolates, those of caprine and ovine origins were more leukotoxic than were isolates of bovine origin (P < 0.01). The two most abundant proteins in the culture supernatant of a highly toxic isolate were purified and identified as the two components of LukM (LukM and LukF'-PV) on the basis of their molecular mass, N-terminal amino acid sequence, and high synergistic activity. LukM/LukF'-PV induced the flattening of bovine PMN at a concentration as low as 3.6 ng/ml (0.1 nM). A higher concentration (18 ng/ml) was necessary to produce the same effect on caprine or ovine PMN. Affinity-purified antibodies to LukM or to LukF'-PV neutralized the leukotoxic effect of all the culture supernatants. They neutralized with the same efficiency the toxic activity of supernatants from lukM/lukF'-PV positive or negative isolates. These results establish that LukM/LukF'-PV is very active on PMN of ruminants and suggest that this leukotoxin could be the most active leukotoxin produced by mastitis isolates. They prompt further studies to delineate the contribution of LukM/LukF'-PV to the pathogenesis of mastitis in ruminants and the protective effect of antibodies to this leukotoxin.

Población y recursos naturales / Population and natural resources

El presente estudio es parte de otro mayor, el mismo que busca contribuir a la elaboración de una agenda de políticas públicas sobre las relaciones entre población, migraciones y desarrollo sostenible. Para ello, se ha propuesto analizar las relaciones entre población, movimientos migratorios, ocupación del territorio y uso de los recursos. En ese marco, el presente texto pretende establecer las relaciones entre población y el uso actual de los recursos naturales, incluyendo aspectos como la identificación de los usos actuales y su relación con la población y la ocupación del territorio, además del análisis de los impactos producidos por la ocupación actual