Abstract
In a retrospective study, the antimicrobial susceptibility of Enterococcus spp. isolated from stored sedimentation dust samples from cattle, pig and poultry barns to 16 antibiotics was determined using a microdilution test. The resistance phenotypes of 70 isolates from different timespans (8 from the 1980s, 15 from the 1990s, 43 from the 2000s and 4 from 2015) were determined. Resistant enterococci were detected in samples from all time periods. Resistances to three or more antibiotics occurred in 69 percent of all isolates. The oldest multidrug resistant isolate was an Enterococcus faecium obtained from a 35-year-old pig barn dust sample. No correlations (ρ = 0.16, p = 0.187) were found between the age of isolates and the number of resistances. Instead, the number of resistances was associated with the origin of the isolates. An exact logistic conditional regression analysis showed significant differences in resistance to ciprofloxacin, erythromycin, penicillin and tylosin between isolates from different animal groups. Interestingly, we isolated ciprofloxacin-resistant E. faecium from pig barn dust before fluoroquinolones were introduced into the market for use in animal husbandry. In conclusion, dust from farm animal houses is a reservoir and carrier of multidrug-resistant Enterococcus spp. People working in barns are unavoidably exposed to these bacteria. Furthermore, it can be hypothesized that emissions from barns of intensive livestock farming contaminate the environment with multidrug resistant enterococci.
Highlights
Enterococcus spp. can be found in the gut microbiota of mammals and birds and are opportunistic pathogens (Byappanahalli et al, 2012)
In a comprehensive study, Hershberger et al (2005) showed that farm animals were a reservoir of antibiotic-resistant enterococci and that resistance was more common on farms using antimicrobials
Further identification to species level by MALDI-TOF MS resulted in 64 E. faecium isolates, five E. hirae isolates and one E. casseliflavus isolate
Summary
Enterococcus spp. can be found in the gut microbiota of mammals and birds and are opportunistic pathogens (Byappanahalli et al, 2012). Enterococcus spp. can infect farm animals and cause nosocomial infections in humans (Byappanahalli et al, 2012). Enterococcus spp. are predominately adapted to their hosts, transmission between animals and humans has been described and is a risk factor for the spread of these organisms (Lu et al, 2002; Kataoka et al, 2014; Lebreton et al, 2014; Milton et al, 2015). In a comprehensive study, Hershberger et al (2005) showed that farm animals were a reservoir of antibiotic-resistant enterococci and that resistance was more common on farms using antimicrobials. Such strains from animals are potentially able to transfer resistance genes to pathogenic bacteria. This concern is one of the reasons why trends of resistances in animal isolates are monitored in member states of the European Union and other areas (EFSA, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
