26 research outputs found
Carriage of methicillin-resistant Staphylococcus pseudintermedius in dogs--a longitudinal study
<p>Abstract</p> <p>Background</p> <p>Methicillin-resistant <it>S. pseudintermedius </it>strains (MRSP) are reported with increasing frequency in bacterial cultures from dogs. The objectives of this study were to determine whether MRSP could be found in dogs several months after a clinically apparent infection and whether the length of carriage varied depending on systemic antimicrobial treatment, diagnosis at time of the first positive MRSP culture and the presence of skin disease or wounds. Thirty-one dogs previously diagnosed with a clinical infection were sampled repeatedly for a minimum of eight months or, with the exception of two dogs, until two consecutive negative results were obtained. Five specified locations were sampled, and the results were evaluated to determine future recommendations concerning sample strategies when screening for MRSP carriage. Information was collected from medical records and questionnaires to evaluate factors that may influence length of carriage.</p> <p>Results</p> <p>The overall median length of MRSP carriage was 11 months (48 weeks). The presence of wounds and signs of dermatitis did not influence length of carriage. Systemic treatment for three weeks or longer with antimicrobial agents to which the bacterium was resistant was associated with prolonged carriage compared to dogs treated for a shorter period of time. Three of five dogs treated with an antimicrobial to which their MRSP-isolates were susceptible (tetracycline) were found to still be MRSP-positive when sampled after the end of treatment. Wound samples had the highest positive MRSP yield (81%) for the positive sample sites, compared to less than 70% for each of the other four sample sites. Cultures from the nostrils were less likely to detect MRSP carriage relative to the pharynx, perineum, wounds and the corner of the mouth.</p> <p>Conclusions</p> <p>Dogs can carry MRSP for more than a year after a clinically apparent infection. Systemic antimicrobial treatment of infections with antimicrobial agents to which the MRSP-bacteria are resistant should be avoided when possible in dogs with possible or confirmed MRSP carriage or infection, since it may prolong time of MRSP carriage. Simultaneous sampling of pharynx, perineum, and the corner of the mouth as well as wounds when present is recommended when screening for MRSP. Cultures from nostrils were shown to be less likely to detect MRSP carriage.</p
Clonal spread of methicillin-resistant Staphylococcus pseudintermedius in Europe and North America: an international multicentre study
Objectives The aim of this study was to determine the phenotypic and genotypic resistance profiles of methicillin-resistant Staphylococcus pseudintermedius (MRSP) and to examine the clonal distribution in Europe and North America. Methods A total of 103 MRSP isolates from dogs isolated from several countries in Europe, the USA and Canada were characterized. Isolates were identified by PCR-restriction fragment length polymorphism (RFLP), antimicrobial susceptibility was determined by broth dilution or gradient diffusion, and antimicrobial resistance genes were detected using a microarray. Genetic diversity was assessed by multilocus sequence typing (MLST), PFGE and spa typing. Staphylococcal cassette chromosome mec (SCCmec) elements were characterized by multiplex PCR. Results Thirteen different sequence types (STs), 18 PFGE types and 8 spa types were detected. The hybrid SCCmec element II-III described in a MRSP isolate was present in 75 (72.8%) isolates. The remaining isolates either had SCCmec type III (nâ=â2), IV (nâ=â6), V (nâ=â14) or VII-241 (nâ=â4) or were non-typeable (nâ=â2). The most common genotypes were ST71(MLST)-J(PFGE)-t02(spa)-II-III(SCCmec) (56.3%) and ST68-C-t06-V (12.6%). In addition to mecA-mediated ÎČ-lactam resistance, isolates showed resistance to trimethoprim [dfr(G)] (90.3%), gentamicin/kanamycin [aac(6âČ)-Ie-aph(2âČ)-Ia] (88.3%), kanamycin [aph(3âČ)-III] (90.3%), streptomycin [ant(6âČ)-Ia] (90.3%), streptothricin (sat4) (90.3%), macrolides and/or lincosamides [erm(B), lnu(A)] (89.3%), fluoroquinolones (87.4%), tetracycline [tet(M) and/or tet(K)] (69.9%), chloramphenicol (catpC221) (57.3%) and rifampicin (1.9%). Conclusions Two major clonal MRSP lineages have disseminated in Europe (ST71-J-t02-II-III) and North America (ST68-C-t06-V). Regardless of their geographical or clonal origin, the isolates displayed resistance to the major classes of antibiotics used in veterinary medicine and thus infections caused by MRSP isolates represent a serious therapeutic challeng
Etiology and antimicrobial susceptibility of udder pathogens from cases of subclinical mastitis in dairy cows in Sweden
<p>Abstract</p> <p>Background</p> <p>A nationwide survey on the microbial etiology of cases of subclinical mastitis in dairy cows was carried out on dairy farms in Sweden. The aim was to investigate the microbial panorama and the occurrence of antimicrobial resistance. Moreover, differences between newly infected cows and chronically infected cows were investigated.</p> <p>Methods</p> <p>In total, 583 quarter milk samples were collected from 583 dairy cows at 226 dairy farms from February 2008 to February 2009. The quarter milk samples were bacteriological investigated and scored using the California Mastitis Test. Staphylococci were tested for betalactamase production and presence of resistance was evaluated in all specific udder pathogens. Differences between newly infected cows and chronically infected cows were statistically investigated using logistic regression analysis.</p> <p>Results</p> <p>The most common isolates of 590 bacteriological diagnoses were <it>Staphylococcus (S) aureus </it>(19%) and coagulase-negative staphylococci (CNS; 16%) followed by <it>Streptococcus (Str) dysgalactiae </it>(9%), <it>Str. uberis </it>(8%), <it>Escherichia (E.) coli </it>(2.9%), and <it>Streptococcus </it>spp. (1.9%). Samples with no growth or contamination constituted 22% and 18% of the diagnoses, respectively. The distribution of the most commonly isolated bacteria considering only bacteriological positive samples were: <it>S. aureus </it>- 31%, CNS - 27%, <it>Str. dysgalactiae </it>- 15%, <it>Str. uberis </it>- 14%, <it>E. coli </it>- 4.8%, and <it>Streptococcus </it>spp. - 3.1%. There was an increased risk of finding <it>S. aureus, Str. uberis </it>or <it>Str. dysgalactiae </it>in milk samples from chronically infected cows compared to findings in milk samples from newly infected cows. Four percent of the <it>S. aureus </it>isolates and 35% of the CNS isolates were resistant to penicillin G. Overall, resistance to other antimicrobials than penicillin G was uncommon.</p> <p>Conclusions</p> <p><it>Staphylococcus aureus </it>and CNS were the most frequently isolated pathogens and resistance to antimicrobials was rare.</p
Molecular analysis of methicillin-resistant Staphylococcus pseudintermedius of feline origin from different European countries and North America
Infection prevention and control interventions in the first outbreak of methicillin-resistant Staphylococcus aureus infections in an equine hospital in Sweden
<p>Abstract</p> <p>Background</p> <p>The first outbreak of methicillin-resistant <it>Staphylococcus aureus </it>(MRSA) infection in horses in Sweden occurred in 2008 at the University Animal Hospital and highlighted the need for improved infection prevention and control. The present study describes interventions and infection prevention control in an equine hospital setting July 2008 - April 2010.</p> <p>Method</p> <p>This descriptive study of interventions is based on examination of policy documents, medical records, notes from meetings and cost estimates. MRSA cases were identified through clinical sampling and telephone enquiries about horses post-surgery. Prospective sampling in the hospital environment with culture for MRSA and genotyping of isolates by <it>spa</it>-typing and pulsed-field gel electrophoresis (PFGE) were performed.</p> <p>Results</p> <p>Interventions focused on interruption of indirect contact spread of MRSA between horses via staff and equipment and included: Temporary suspension of elective surgery; and identification and isolation of MRSA-infected horses; collaboration was initiated between authorities in animal and human public health, human medicine infection control and the veterinary hospital; extensive cleaning and disinfection was performed; basic hygiene and cleaning policies, staff training, equipment modification and interior renovation were implemented over seven months.</p> <p>Ten (11%) of 92 surfaces sampled between July 2008 and April 2010 tested positive for MRSA <it>spa</it>-type 011, seven of which were from the first of nine sampling occasions. PFGE typing showed the isolates to be the outbreak strain (9 of 10) or a closely related strain. Two new cases of MRSA infection occurred 14 and 19 months later, but had no proven connections to the outbreak cases.</p> <p>Conclusions</p> <p>Collaboration between relevant authorities and the veterinary hospital and formation of an infection control committee with an executive working group were required to move the intervention process forward. Support from hospital management and the dedication of staff were essential for the development and implementation of new, improved routines. Demonstration of the outbreak strain in the environment was useful for interventions such as improvement of cleaning routines and interior design, and increased compliance with basic hygienic precautions. The interventions led to a reduction in MRSA-positive samples and the outbreak was considered curbed as no new cases occurred for over a year.</p
Characterisation of bacterial growth and antimicrobial susceptibility patterns in canine urinary tract infections
The immune response during acute and chronic phase of bovine mastitis
The aims of this thesis were to describe the innate and adapted immune response during acute and chronic phase of bovine Staphylococcus aureus (S. aureus) mastitis, and to investigate why the infection often becomes persistent. The potential of the milk acute phase proteins (APP) haptoglobin and serum amyloid A (SAA) as indicators of chronic sub-clinical mastitis was also evaluated, as well as the preventive and therapeutic effects of the immunomodulator Ă1,3-glucan against intramammary S. aureus infection. After intramammary inoculation of S. aureus, acute clinical mastitis developed and was transformed to chronic sub-clinical mastitis with controlled use of penicillin. Blood and milk samples from infected and healthy quarters were collected during five weeks, and analysed for APP and lymphocyte sub-populations. The most prominent features were increased APP concentrations in serum, and in milk from infected quarters, but not in milk from control quarters, during both acute and chronic phase of mastitis, and an increased proportion of B-lymphocytes and cellular expression of B-cell antigen in blood, infected and healthy quarters. The results indicate that both clinical and sub-clinical mastitis exert effects on local, as well as systemic, innate and adapted immune responses. The B-cell response could be one explanation why the immune system failed to eliminate the infection. When studying naturally occurring cases of chronic sub-clinical mastitis, a large variation in expression of APP in milk, and a discrepancy between the levels of APP and adenosine triphosphate (ATP), an indirect measurement of the milk somatic cell count, was observed. In most cases, healthy cows had undetectable levels of milk APP. The results indicate that milk haptoglobin and SAA can be used as indicators of udder health. Intramammary infusions of Ă1,3-glucan failed to prevent experimental S. aureus infection at drying-off, and to eliminate S. aureus infection in cows with chronic sub-clinical mastitis. However, an immunostimulating effect was observed as the expression of MHC class II was increased on lymphocytes from S. aureus-infected quarters. Prevention and elimination of intramammary S. aureus infections using immunomodulators, like Ă1,3-glucan, need further studies
Experimentell utvÀrdering av vÀggreppsmÀtaren RT3 Curve
This thesis presents an experimental evaluation of the road grip estimator RT3 Curve manufactured by Halliday Technologies Inc. RT3 Curve can be pictured as a small trailer that is coupled behind a car. It measures the friction between two surfaces by two measuring wheels mounted with fixed slip angles. The vehicle dynamic term slip angle is the angle between a rolling wheel's actual direction of travel and the direction at which it is pointing. The slip angle causes side forces when the trailer is pulled behind the car. Mounted in the wheel center axis is a load cell mounted that measures the changes in the side forces that arise due to friction between the tire and the road surface. RT3 Curve is among other things intended to be used for measurement of winter maintenance processes. RT3 Curve is capable of measuring road grip at all kinds of road conditions as well as on straight, curved or cambered roads. It has, however, a limitation when it comes to curves where the minimum radius as specified by the manufacturer is 50 m.In this experimental study the relationship between road grip and curve radius has been investigated. The main question was how the road grip changes when turning compared with driving on a straight road. It has been found that the road grip differs from the reference value at a radius of about 20 m. The reference value is determined from runs on a straight section adjacent to the curve/roundabout where the measurement was made. An empirical function is formulated from the experimental data. This relationship allows us to compensate for the deviations in road grip that occurs when cornering. The model is validated only for surfaces with high friction such as asphalt. Road grip is very difficult to measure and it depends on both the tire and the road characteristics. The resulting model has to be developed and more extensive measurements has to be carried out on different surfaces such as dry asphalt, wet asphalt, snow, ice, etc.Validerat; 20150609 (global_studentproject_submitter