The risk appears greatest in those handling or managing livestock, for example in a study where resistant bacteria were monitored in farm labourers and neighbours after chickens receiving an antibiotic in their feed.[50] Manure may also be contain antibiotic-resistant Staphylococcus aureus bacteria which can infect humans.[51][52] In 2017, the WHO included methicillin-resistant S. aureus (MRSA) in its priority list of 12 antibiotic-resistant bacteria, urging the need to search for new and more effective antibiotics against it. There also has been an increase in the number of bacterial pathogens resistant to multiple antimicrobial agents, including MRSA, which have recently emerged into different lineages. Some of them are associated with livestock and companion animals that are then able to be transmitted to humans, also called livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA).