Nasal swabs and stool samples were either self-collected (dog owners and veterinarians) following detailed instructions or sampled by the trained personal (pig farmers and control group). Nasal specimens were taken using swabs with transport medium (Transystem, COPAN, Italy) and 2–3 g of feces was taken with specialized spoon and placed into a container (Aptaca, Canelli, Italy). All samples were immediately transported to the microbiology laboratory of the University of Tartu and stored at −80 °C for a maximum of 2 months. If quick transportation was not available, samples were stored at −20 °C for a maximum of 48 h.
Thawed nasal swabs were plated onto blood agar and incubated at 37 °C for 24–48 h in ambient air. All colonies with different morphology were isolated and identified using MALDI-TOF mass spectrometry (Bruker Daltonics, Bremen, Germany).
Defrosted fecal samples were plated on selective medium for isolation of ESBL-producing organisms (BrillianceTM ESBL Agar, Oxoid, Basingstoke, UK) and incubated at 37 °C for 24 h. Then two colonies per plate with morphology suggestive of Escherichia coli or the Klebsiella, Enterobacteria, Serratia, and Citrobacter group (KESC) were selected and confirmed at species level using MALDI-TOF mass spectrometry (Bruker Daltonics, Bremen, Germany).
Thawed nasal swabs were plated onto blood agar and incubated at 37 °C for 24–48 h in ambient air. All colonies with different morphology were isolated and identified using MALDI-TOF mass spectrometry (Bruker Daltonics, Bremen, Germany).
Defrosted fecal samples were plated on selective medium for isolation of ESBL-producing organisms (BrillianceTM ESBL Agar, Oxoid, Basingstoke, UK) and incubated at 37 °C for 24 h. Then two colonies per plate with morphology suggestive of Escherichia coli or the Klebsiella, Enterobacteria, Serratia, and Citrobacter group (KESC) were selected and confirmed at species level using MALDI-TOF mass spectrometry (Bruker Daltonics, Bremen, Germany).