Bärarskap av meticillinresistent Staphylococcus pseudintermedius (MRSP) hos svenska hundar

During the last years, meticillin resistant Staphylococcus pseudintermedius (MRSP) have caused an increasing number of infections in Swedish dogs. MRSP is resistant against a majority of the antimicrobials available for dogs in Sweden, making it difficult to treat the infection. Our knowledge of the bacterium is limited, making it hard to handle infected dogs in a proper way. The aim of this study was to investigate for how long time dogs, who have an infection caused by MRSP, become carriers of the bacterium. Other factors like treatment with antimicrobials, the correlation between clinical symptoms and carriage, common diagnoses and institutionalization where also looked upon. Increased knowledge in this field will improve the handling of patients and the advises to owners. Bacterial swabs where sampled from 23 Swedish dogs with known carriage of MRSP. Samples where collected on two occasions from four different locations: the nose, around anus, the pharynx and from any infected area on the dog. If the dog was asymptomatic, samples were instead taken from lip commissures. Culturing and identificationing and antimicrobial susceptibility tests were carried out in compliance with chosen method. Oxacillin resistant colonies where indirectly tested for the presence of the mecA gene with latexagglutination and this is used to confirm it as a MRSP. Among the 23 dogs that where sampled, almost 86 % where still positive within one to five months time. After six to thirteen months, almost 77 % of the dogs were sampled negative for MRSP. MRSP was isolated from one dog 12 months after it was first diagnosed. All of the dogs had been treated with antimicrobials within three months prior to MRSP culture. Among the dogs that tested positive for MRSP both dogs with and without clinical symptoms of infections where found. Above all, two diagnoses where prominent in the study; post operative wound infections and pyoderma. All of the dogs had been treated at veterinary clinics and 16 of 23 dogs had been hospitalised more than two nights. Rigourous hygiene routines are imperative in preventing spread of infection. Prudent use of antimicrobials and increased bacterial sampling, including resistance patterns, are further steps essential in reducing the selection for MRSP.De senaste åren har ett ökat antal fall av infektioner orsakade av meticillinresistenta Staphylococcus pseudintermedius (MRSP) drabbat hundar i Sverige. MRSP är resistent mot en stor del av de antibiotika som används till hundar i Sverige idag, något som gör den svårbehandlad om en infektion tillstöter. Vår kunskap om bakterien har varit begränsad och detta har gjort hanteringen av smittade hundar svår. Syftet med studien var att undersöka hur länge hundar som haft en infektion orsakad av MRSP (meticillinresistent Staphylococcus pseudintermedius) blir bärare av bakterien. Vi tittade även på andra faktorer i samband med smitta såsom antibiotikabehandling, korrelation mellan kliniska symptom och bärarskap, vanliga diagnoser hos smittad hund samt stationärvårdsbehandling som riskfaktor. Med ökad kunskap om hur bakterien beter sig kan hantering i samband med besök på djursjukhus och rådgivning till djurägare förbättras. Bakterieprover togs från 23 svenska hundar med tidigare känt bärarskap av MRSP. Prover togs vid två upprepade tillfällen från fyra olika lokalisationer på hunden; nos, perianalt, svalg samt infekterat område på hunden, och om inget sådant fanns togs provet från mungipan. Odling, typning och resistensbestämning utfördes enligt gängse metod vid SVA (Statens Veterinärmedicinska Anstalt). Oxacillinresistenta kolonier testades indirekt för förekomst av mecA-genen med hjälp av latexagglutination. De som var positiva benämndes som en MRSP. Av de hundar som provtogs en till fem månader från det att MRSP påvisats första gången var närmare 86 % positiva. Bland de hundar som provtogs sex till tretton månader från det att MRSP påvisats första gången testades ca 77 % negativa. En hund provtogs, och befanns vara positiv avseende 12 månader efter att den diagnosticerades första gången. Samtliga hundar hade blivit behandlade med antibiotika inom tre månader före det att MRSP påvisades första gången. Inget samband mellan kliniska symptom och smitta kunde påvisas. Bland de hundar som ingick i studien kunde framför allt två diagnoser urskiljas; infekterade operationssår och pyodermier (hudinfektioner). Alla hundar i studien hade besökt veterinärkliniker och 16 av 23 hundar hade stationärvårdsbehandlats i mer än två dagar före den första provtagningen som påvisande MRSP. Skärpta hygienrutiner, utökad bakterieprovtagning med resistensbestämning och ansvarsfull antibiotikaanvändning är väsentliga åtgärder för att förebygga selektion och spridning av MRSP

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