Macrolide Resistance in Microorganisms at Antimicrobial-Free Swine Farms

Abstract

To investigate the relationship between agricultural antimicrobial use and resistance, a variety of methods for quantification of macrolide-lincosamide-streptogramin B (MLS B ) resistance were applied to organic swine farm manure samples. Fluorescence in situ hybridization was used to indirectly quantify the specific rRNA methylation resulting in MLS B resistance. Using this method, an unexpectedly high prevalence of ribosomal methylation and, hence, predicted MLS B resistance was observed in manure samples from two swine finisher farms that reported no antimicrobial use (37.6% ؎ 6.3% and 40.5% ؎ 5.4%, respectively). A culture-based method targeting relatively abundant clostridia showed a lower but still unexpectedly high prevalence of resistance at both farms (27.7% ؎ 11.3% and 11.7% ؎ 8.6%, respectively), while the prevalence of resistance in cultured fecal streptococci was low at both farms (4.0%). These differences in the prevalence of resistance across microorganisms suggest the need for caution when extrapolating from data obtained with indicator organisms. A third antimicrobial-free swine farm, a breeder-to-finisher operation, had low levels of MLS B resistance in manure samples with all methods used (<9%). Tetracycline antimicrobials were detected in manure samples from one of the finisher farms and may provide a partial explanation for the high level of MLS B resistance. Taken together, these findings highlight the need for a more fundamental understanding of the relationship between antimicrobial use and the prevalence of antimicrobial resistance.

Effects of the antimicrobial tylosin on the microbial community structure of an anaerobic sequencing batch reactor

“…FISH was performed as previously described (De los Reyes et al, 1997;Zhou et al, 2009) using the oligonucleotide probes and formamide concentrations listed in Table I. The cells were stained on the slide with 1 µg/mL 4′,6-diamidino-2-phenylindole (DAPI) (Sigma-Aldrich, St. Louis, MO) and citifluor (Marivac Limited, Halifax, NS, Canada) was used as antifading agent.…”

“…Automated image processing was performed using the software Visilog v6 (NOESIS, Gif sur Yvette, France) and classification was performed using fuzzy c-means clustering with manual quality control (Zhou et al, 2007). MLS B resistance was quantified indirectly through hybridization of an oligonucleotide probe (MLS B in Table I) to unmethylated, MLS B -sensitive cells as described by Zhou et al (2009). The prevalence of ribosomal methylation and presumed MLS B resistance was calculated by subtracting MLS B probe-positive cells from the Bact0338 count and normalizing to the Bact0338 count.…”

Effects of Swine Manure on Macrolide, Lincosamide, and Streptogramin B Antimicrobial Resistance in Soils

“…Although the MLS B antimicrobials are chemically distinct, methylation or mutation of a single base of the 23S rRNA prevents binding and results in cross-resistance to all three classes (29). The prevalence of MLS B antimicrobial resistance in the microbial community can therefore be quantified indirectly by hybridization of an oligonucleotide probe to unmethylated, MLS B -sensitive ribosomes, using either membrane hybridization (1,10) or FISH (31). These methods do not require culturing or a comprehensive knowledge of the diversity of resistance gene sequences, but they do not detect resistance to specific antimicrobials that results from other mechanisms, such as macrolide efflux.…”

Effects of Chlorophyll-Derived Efflux Pump Inhibitor Pheophorbideaand Pyropheophorbideaon Growth and Macrolide Antibiotic Resistance of Indicator and Anaerobic Swine Manure Bacteria

“…21% and 32%) [73]. However, according to other previous studies [105,106], background levels of erythromycin and macrolide resistance in nonmedicated swine fecal and manure bacterial communities can already be as high as approximately 40% and are enhanced further by the administration of compounds with antimicrobial activities [62][63][64]. In our study, tylosin had last been used 31 days and 4-4.5 months prior to the last pit emptying and days of sampling, respectively, and consequently was not detected by HPLC in the manure.…”

“…More likely, however, the high levels of erythromycin and tylosin resistance were partly the outcome of the recent administration of oxytetracycline, lincomycin, and the heavy metals copper and zinc, these compounds can indirectly enhance antimicrobial incl. macrolide resistance through coselection [105,[108][109][110][111][112][113].…”