Performance characteristics and costs of serological tests for brucellosis in a pastoralist community of northern Tanzania.

The control of brucellosis across sub-Saharan Africa is hampered by the lack of standardized testing and the use of tests with poor performance. This study evaluated the performance and costs of serological assays for human brucellosis in a pastoralist community in northern Tanzania. Serum collected from 218 febrile hospital patients was used to evaluate the performance of seven index tests, selected based on international recommendation or current use. We evaluated the Rose Bengal test (RBT) using two protocols, four commercial agglutination tests and a competitive enzyme-linked immunosorbent assay (cELISA). The sensitivity, specificity, positive predictive value, negative predictive value, Youden's index, diagnostic accuracy, and per-sample cost of each index test were estimated. The diagnostic accuracy estimates ranged from 95.9 to 97.7% for the RBT, 55.0 to 72.0% for the commercial plate tests, and 89.4% for the cELISA. The per-sample cost range was $0.69-$0.79 for the RBT, $1.03-$1.14 for the commercial plate tests, and $2.51 for the cELISA. The widely used commercial plate tests performed poorly and cost more than the RBT. These findings provide evidence for the public health value of discontinuing the use of commercial agglutination tests for human brucellosis in Tanzania.

Socially vs. Privately Optimal Control of Livestock Diseases: A Case for Integration of Epidemiology and Economics.

This paper aims to illustrate the interdependencies between key epidemiological and economic factors that influence the control of many livestock infectious diseases. The factors considered here are (i) farmer heterogeneity (i.e., differences in how farmers respond to a perceived disease risk), (ii) off-farm effects of farmers' actions to control a disease (i.e., costs and benefits borne by agents that are external to the farm), and (iii) misalignment between privately and socially optimal control efforts (i.e., privately optimal behavior not conducive to a socially optimal outcome). Endemic chronic diseases cause a wide range of adverse social and economic impacts, particularly in low-income countries. The actions taken by farmers to control livestock diseases minimize some of these impacts, and heterogeneity in those actions leads to variation in prevalence at the farm level. While some farmers respond to perceived disease risks, others free-ride on the actions of these individuals, thereby compromising the potential benefits of collective, coordinated behavior. When evaluating a plausible range of disease cost to price of control ratios and assuming that farmers choose their privately optimal control effort, we demonstrate that achievement of a socially optimal disease control target is unlikely, occurring in <25% of all price-cost combinations. To achieve a socially optimal disease control outcome (reliant on farmers' voluntary actions), control policies must consider farmer heterogeneity, off-farm effects, and the predicted uptake of control measures under the assumption of optimized behavior.

River water analysis using a multiparametric approach: Portuguese river as a case study.

The Ave River in northern Portugal has a history of riverbanks and water quality degradation. The river water quality was assessed by physicochemical, biological (macroinvertebrates) and microbiological (Enterococcus spp. and Escherichia coli) parameters in six locations (A-F, point A being the nearest to the source) throughout its course during a year. Epilithic biofilms were studied through polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE). Antimicrobial susceptibility testing helped with selecting isolates (n = 149 E. coli and n = 86 enterococci) for further genetic characterization. Pursuant to physicochemical and macroinvertebrates-based parameters, the river water was of reasonable quality according to European legislation (Directive 2000/60/EC). However, the microbiological analysis showed increased fecal contamination downstream from point C. At point D, four carbapenem-resistant E. coli isolates were recovered. Paradoxically, point D was classified as a point of 'Good Water Quality' according to macroinvertebrates results. Point F presented the highest contamination level and incidence of multidrug-resistant (MDR) isolates in the water column (13 MDR enterococci out of 39 and 33 MDR E. coli out of 97). Epilithic biofilms showed higher diversity in pristine points (A and B). Thus, biological and microbiological parameters used to assess the water quality led to divergent results; an outcome that reinforces the need for a holistic evaluation.

Occurrence of mcr-1 in Escherichia coli from rabbits of intensive farming.

The emergence of mobile colistin resistance genes (mcr) is yet another challenge in the fight against antimicrobial resistance, with reports proving the dissemination of these genes in different countries and different environments being of great concern. In the present study, we describe the recovery of three E. coli strains with mcr-1 gene in IncHI2 plasmids from intestinal content of necropsied meat rabbits reared in two intensive production systems in Portugal. Our findings are worrisome, given the high level of dependence on the usage of antibiotics in rabbit rearing and call for the development and implementation of an active surveillance system in this species.

A multilevel study of the environmental determinants of swine ascariasis in England.

Ascariasis is considered a common parasitosis of swine worldwide. The disease causes significant economic losses due to its effect on feed conversion ratio and liver condemnations at slaughter (liver milk spots). This study aimed to characterise the between-farm and spatial variance in porcine ascariasis in England and to assess the association between the percentage of infected animals and potential environmental risk factors, including production system, socioeconomic deprivation, soil characteristics (pH, topsoil bulk density, topsoil organic matter, topsoil texture class, soil water regime, topsoil available water capacity, and elevation), and climatic conditions (relative humidity, air temperature, and rainfall) before slaughter. Post-mortem inspection results were provided by the Food Standards Agency and comprised information about the number of rejected livers, the number of animals sent to slaughter and the production system. All farms were georeferenced based on the postcode, which allowed the assessment of the area index of socioeconomic deprivation and the extraction of soil and climatic characteristics available in different online databases. Under a multilevel framework with adjustment for spatial autocorrelation, a standard linear mixed model was fitted to estimate the association between these determinants and the percentage of infected animals. From 2,513,973 English farmed pigs included in the study, 4.3% had their livers rejected due to milk spots. The percentage of infected pigs per batch ranged from 0% to 100%. The highest percentages were found in Surrey, East and West Sussex (8.9%) and lowest in Leicestershire, Rutland and Northamptonshire (2.0%). Significant associations were found at multivariable analysis between the proportion of infection and the number of animals sent to slaughter (ß=-0.005; 95%CI=-0.005, -0.004), soil texture (peat compared to coarse textured soils; ß=-0.516; 95%CI=-1.010, -0.063), relative humidity (ß=0.011; 95%CI=0.006, 0.015), mean temperature (ß=0.007; 95%CI=0.003, 0.012), and rainfall (ß=0.022; 95%CI=0.004, 0.037). In conclusion, our findings suggest that ascariasis can be influenced by a complex network of environmental factors. Future research needs to acknowledge these intermingled relationships to guide the development and application of control measures by the industry.

Chemical Composition, Antibacterial, Antibiofilm and Synergistic Properties of Essential Oils from Eucalyptus globulus Labill. and Seven Mediterranean Aromatic Plants.

Essential oils (EOs) from Eucalyptus globulus Labill. ssp. globulus and from Mediterranean autochthonous aromatic plants - Thymus mastichina L., Mentha pulegium L., Rosmarinus officinalis L., Calamintha nepeta (L.) Savi ssp. nepeta, Cistus ladanifer L., Foeniculum vulgare L., Dittrichia viscosa (L.) Greuter ssp. viscosa - were extracted by hydrodistillation and characterized by GC-FID and NMR spectroscopy. EOs were evaluated for antimicrobial properties against several bacterial strains, using diverse methods, namely, the agar disc-diffusion method, the microdilution method, the crystal violet assay and the Live/Dead staining for assessment of biofilm formation. Potential synergy was assessed by a checkerboard method. EOs of R. officinalis and C. ladanifer showed a predominance in monoterpene hydrocarbons (> 60%); EOs of C. nepeta, M. pulegium, T. mastichina, E. globulus and F. vulgare were rich in oxygenated monoterpenes (62 - 96%) whereas EO of D. viscosa was mainly composed of oxygenated sesquiterpenes (54%). All EOs showed antimicrobial activity; M. pulegium and E. globulus generally had the strongest antimicrobial activity. EO of C. nepeta was the most promising in hampering the biofilm formation. The combinations D. viscosa/C. nepeta and E. globulus/T. mastichina were synergistic against Staphylococcus aureus. These results support the notion that EOs from the aromatic plants herein reported should be further explored as potential pharmaceuticals and/or food preservatives.

Coagulase-Positive Staphylococcus: Prevalence and Antimicrobial Resistance.

Staphylococcus pseudintermedius is the most prevalent coagulase-positive Staphylococcus inhabitant of the skin and mucosa of dogs and cats, causing skin and soft tissue infections in these animals. In this study, coagulase-positive Staphylococcus species were isolated from companion animals, veterinary professionals, and objects from a clinical veterinary environment by using two particular culture media, Baird-Parker RPF agar and CHROMagar Staph aureus. Different morphology features of colonies on the media allowed the identification of the species, which was confirmed by performing a multiplex polymerase chain reaction (PCR). Among 23 animals, 15 (65.2%) harbored coagulase-positive Staphylococcus, being 12 Staphylococcus pseudintermedius carriers. Four out of 12 were methicillin-resistant S. pseudintermedius (MRSP). All veterinary professionals had coagulase-positive Staphylococcus (CoPS) species on their hands and two out of nine objects sampled harbored MRSP. The antimicrobial-resistance pattern was achieved for all isolates, revealing the presence of many multidrug-resistant CoPS, particularly S. pseudintermedius . The combined analysis of the antimicrobial-resistance patterns shown by the isolates led to the hypothesis that there is a possible crosscontamination and dissemination of S. aureus and S. pseudintermedius species between the three types of carriers sampled in this study that could facilitate the spread of the methicillin-resistance phenotype.

Microbial interaction between a CTXM-15 -producing Escherichia coli and a susceptible Pseudomonas aeruginosa isolated from bronchoalveolar lavage: influence of cefotaxime in the dual-species biofilm formation.

Two isolates, Escherichia coli ella00 and Pseudomonas aeruginosa ella01, obtained from bronchoalveolar lavage, were found to be closely associated in clusters in agar medium. Escherichia coli ella00 was multidrug resistant and CTXM-15 extended-spectrum ß-lactamase producer, while P. aeruginosa ella01 was susceptible to all antimicrobials tested. These observations impelled for further studies aimed to understand their microbial interaction. The P. aeruginosa ella01 biofilm-forming capacity was reduced and not affected when it was co-cultured with E. coli ella00 and E. coli ATCC 25922 respectively. Interestingly, the co-culture of ella isolates in the presence of high concentrations, such as 160 µg ml(-1) , of cefotaxime allowed the formation of more biofilm than in the absence of the antibiotic. As revealed by fluorescence in situ hybridization, in co-culture, P. aeruginosa ella01 survived and subsequently flourished when exposed to this third-generation cephalosporin at a concentration 10 × higher than its minimum inhibitory concentration (MIC), and this was mostly due to ß-lactamases production by E. coli ella00. In fact, it was demonstrated by high-performance liquid chromatography that cefotaxime was absent for the culture medium 4 h after application. In conclusion, we demonstrate that bacterial species can interact differently depending on the surrounding conditions (favourable or stressing), and that those interactions can switch from unprofitable to beneficial.

Prevalence of antimicrobial resistance in enteric Escherichia coli from domestic pets and assessment of associated risk markers using a generalized linear mixed model.

Antimicrobial resistance (AMR) is a growing global public health problem, which is caused by the use of antimicrobials in both human and animal medical practice. The objectives of the present cross-sectional study were as follows: (1) to determine the prevalence of resistance in Escherichia coli isolated from the feces of pets from the Porto region of Portugal against 19 antimicrobial agents and (2) to assess the individual, clinical and environmental characteristics associated with each pet as risk markers for the AMR of the E. coli isolates. From September 2009 to May 2012, rectal swabs were collected from pets selected using a systematic random procedure from the ordinary population of animals attending the Veterinary Hospital of Porto University. A total of 78 dogs and 22 cats were sampled with the objective of isolating E. coli. The animals' owners, who allowed the collection of fecal samples from their pets, answered a questionnaire to collect information about the markers that could influence the AMR of the enteric E. coli. Chromocult tryptone bile X-glucuronide agar was used for E. coli isolation, and the disk diffusion method was used to determine the antimicrobial susceptibility. The data were analyzed using a multilevel, univariable and multivariable generalized linear mixed model (GLMM). Several (49.7%) of the 396 isolates obtained in this study were multidrug-resistant. The E. coli isolates exhibited resistance to the antimicrobial agent's ampicillin (51.3%), cephalothin (46.7%), tetracycline (45.2%) and streptomycin (43.4%). Previous quinolone treatment was the main risk marker for the presence of AMR for 12 (ampicillin, cephalothin, ceftazidime, cefotaxime, nalidixic acid, ciprofloxacin, gentamicin, tetracycline, streptomycin, chloramphenicol, trimethoprim-sulfamethoxazole and aztreonam) of the 15 antimicrobials assessed. Coprophagic habits were also positively associated with an increased risk of AMR for six drugs, ampicillin, amoxicillin-clavulanic acid, cephamycin, ciprofloxacin, streptomycin, and trimethoprim-sulfamethoxazole. In summary, pets with a record of one or more previous quinolone treatments and exhibiting coprophagic habits were at an increased risk of harboring multidrug-resistant E. coli strains in their feces compared to pets without these characteristics. AMR is a serious global problem, and assessing the risk markers for the presence of drug-resistant bacteria in pets, a very close source of resistance determinants to humans, is essential for the implementation of safe handling procedures for companion animals and for the prudent selection of antimicrobial compounds in veterinary practice.

High prevalence of multidrug-resistant Escherichia coli and Enterococcus spp. in river water, upstream and downstream of a wastewater treatment plant.

In this study, microbial quality and antimicrobial resistance of faecal bacteria from a Portuguese river were assessed. River water samples collected upstream and downstream of a wastewater treatment plant, throughout a 3-month period, were used for the enumeration of Escherichia coli and Enterococcus spp. The highest numbers found for E. coli and enterococci were 1.1 × 104 and 1.2 × 104 colony forming units (CFU)/100 ml, respectively. In total, 144 isolates of E. coli and 144 of enterococci were recovered and tested for antimicrobial susceptibility; 104 E. coli and 78 Enterococcus spp. showed resistance to one or more antimicrobial drugs. Overall, 70 and 32 different resistance patterns were found for E. coli and enterococci, respectively. One E. coli showed resistance to imipenem and 29 isolates were extended spectrum ß-lactamase-producers. Multidrug-resistant E. coli belonged mostly to groups A, B1 and group D. Enterococcus spp. were mostly resistant to rifampicin, tetracycline, azithromycin and erythromycin; six isolates showed resistance to vancomycin, presenting the VanA phenotype. The high levels of E. coli and enterococci and the remarkable variety of antimicrobial resistance profiles, reinforces the theory that these river waters can be a pool of antimicrobial resistance determinants, which can be easily spread among different bacteria and reach other environments and hosts.

Spread of multidrug-resistant Enterococcus faecalis within the household setting.

Advances in veterinary medicine have resulted in the survival of many animals with severe illness or infectious diseases. In addition, increased usage of antimicrobial agents for veterinary purposes has contributed to the worldwide problem of increasing antimicrobial resistance. The objective of this study was to contribute to better understand the potential and implications for the spread of antimicrobial-resistant enterococci between pets receiving antimicrobial treatments and their owners. Three household aggregates (HA A, B, and C) were selected for this study. Information was collected on individual and clinical parameters of both humans and animals that cohabit. For this study, samples of feces, oral secretions, skin and fur of pets, as well as owners' feces and hands and exposed household surfaces and objects were also collected. All enterococci isolates were analyzed for antimicrobial susceptibility. Based on the antimicrobial resistance patterns and origin of isolates, ERIC-PCR analysis was performed on selected isolates to evaluate phylogenetic relationships. In all three HA, Enterococcus faecalis clonal spread was detected between pets and the respective owners, confirming the in-home interanimal species dissemination. Additionally, fecal enterococci colonization of other body parts of the same animal and dissemination of those same enterococci to household surfaces and objects were also observed. Our results demonstrate that enterococcal clones were found in pets in multiple body sites, their human cohabitants, and shared domestic objects.