Dissertation: Livestock-associated methicillin-resistant Staphylococcus aureus – studies on prevention of zoonotic transmission

Despite frequent animal contacts, prevalence of zoonotic bacteria resistant to antibiotics in veterinarians equals prevalence in the rest of the population. Veterinarians’ adherence to hygiene recommendations and hand hygiene facilities are not always adequate especially in stables. Educating both veterinarians, farmers and stable owners about the importance of hygiene in the prevention of the transmission of zoonotic pathogens is crucial.

In her PhD thesis Marie Verkola, DVM, M.Soc.Sc., studied the prevalence of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) and extended-spectrum betalactamase (ESBL) producing enterobacteria in veterinarians in Finland as well as ambulatory livestock and equine veterinarians’ adherence to hygiene recommendations to protect themselves and their patients from resistant bacteria. In addition, she investigated colonization of LA-MRSA in Finnish pigs and compared the isolated strains to surveillance strains from the Finnish Food Authority. To decrease LA-MRSA prevalence in pigs, a trial was initiated to applicate bacterial viruses i.e. bacteriophages to LA-MRSA-positive pigs.

Prevalence of LA-MRSA in veterinarians was 0.3% and prevalence of ESBL-bacteria 3.0%. This was the first time LA-MRSA was detected in a veterinarian in Finland indicating that the risk of transmission exists for people working in close contact with livestock also in Finland. According to the veterinarians, hand hygiene facilities were more often inadequate in stables than on farms. Veterinarians’ compliance to hand hygiene recommendations and use of protective equipment was also less adequate in stables than on farms.

LA-MRSA levels detected in the nares and on the skin of the sampled pigs were low. The isolated strains belonged almost exclusively to the most prevalent spa genotype in Finnish pigs and humans. The strains were genetically closely related to the strains from national surveillance, indicating that the strains belonging to this successful spa type have been exceptionally stable during several years. A closer analysis of these strains may help to determine why this spa type is more successful than other spa types.

In the phage trial it was not possible to decrease or eradicate LA-MRSA from pigs. This may be related to the low bacterial levels in connection with asymptomatic carriage. However, the study provided useful information for phage therapy in humans.

Antimicrobial resistance in bacteria has been estimated to cause around a million deaths a year globally. Many of these bacteria are zoonotic. In Finland, especially methicillin-resistant Staphylococcus aureus and ESBL-enterobacteria are detected in both animals and humans. In Continental Europe, LA-MRSA is prevalent especially in pigs and in veal calves and has been shown to pose a risk to people working in close contact with livestock, such as farmers and veterinarians. In Finland, LA-MRSA was detected in 77% of pig slaughter batches in the most recent survey. The proportion of LA-MRSA of human MRSA surveillance samples has been increasing in recent years.

Marie Verkola, DVM, M. Soc. Sc.: Livestock-associated methicillin-resistant Staphylococcus aureus – studies on prevention of zoonotic transmission

Friday 13 May 2022 at 1 pm Metsätieteiden talo, lecture hall 2 (Raisio-Sali), Latokartanonkaari 7, Viikki.

Unitube livestream: https://video.helsinki.fi/unitube/live-stream.html?room=l12

Digital version of the PhD thesis