Hierarchal clustering yields insight into multidrug-resistant bacteria isolated from a cattle feedlot wastewater treatment system

Abstract

Forty-two percent of Escherichia coli and 58% of Enterococcus spp. isolated from cattle feedlot runoff and associated infiltration basin and constructed wetland treatment system were resistant to at least one antibiotic of clinical importance; a high level of multidrug resistance (22% of E. coli and 37% of Enterococcus spp.) was observed. Hierarchical clustering revealed a closely associated resistance cluster among drug-resistant E. coli isolates that included cephalosporins (ceftiofur, cefoxitin, and ceftriaxone), aminoglycosides (gentamycin, kanamycin, and amikacin), and quinolone nalidixic acid; antibiotics from these classes were used at the study site, and cross-resistance may be associated with transferrable multiple-resistance elements. For Enterococcus spp., co-resistance among vancomycin, linezolid, and daptomycin was common; these antibiotics are reserved for complicated clinical infections and have not been approved for animal use. Vancomycin resistance (n = 49) only occurred when isolates were resistant to linezolid, daptomycin, and all four of the MLSB (macrolide-lincosamide-streptogramin B) antibiotics tested (tylosin, erythromycin, lincomycin, and quinipristin/dalfopristin). This suggests that developing co-resistance to MLSB antibiotics along with cyclic lipopeptides and oxazolidinones may result in resistance to vancomycin as well. Effects of the treatment system on antibiotic resistance were pronounced during periods of no rainfall and low flow (long residence time). Increased hydraulic loading (short residence time) under the influence of rain caused antibiotic-resistant bacteria to be flushed through the treatment system. This presents concern for environmental discharge of multidrug-resistant organisms relevant to public health.

Assessing quality of Medicago sativa silage by monitoring bacterial composition with single molecule, real-time sequencing technology and various physiological parameters

“…The minor bacterial species, E. durans , is considered undesirable, even though no report has yet indicated any pathogenic effect of this bacterium on dairy cows. Previous studies have however shown its correlation with antibiotic gene transfer24. One possible mechanism of LAB additives in shaping the silage microbiota during the fermentation process was their ability in releasing antagonistic materials25.…”

Industrial Food Animal Production and Community Health

“…Figure 1 illustrates how IFAP can lead to adverse health effects in nearby communities via the generation and spread of microbial and chemical hazards. Studies have identified bacterial pathogens, such as antibiotic-resistant strains of Staphylococcus and Enterococcus, in and around IFAP operations, including colonizing animals and surfaces [7][8][9][10], in manure [11][12][13][14][15][16], and carried by flies [17,18] and rats [19] near operations. IFAP is also a source of airborne pathogens [8,[20][21][22], endotoxins [23], particulate matter (PM) [24], hydrogen sulfide (H 2 S), ammonia, odorous chemicals, and other contaminants [23,[25][26][27][28], which may be spread from operations to the downwind environment, e.g., via ventilation fans and emissions from decomposing manure [7,8,26,27,[29][30][31][32].…”

A model assessment of the importance of direct photolysis in the photo-fate of cephalosporins in surface waters: Possible formation of toxic intermediates

“…In particular, antibiotics have been detected in the ng L À1 to lg L À1 range in surface waters, where the possible bioaccumulation and the induction of drug resistance in bacteria may affect environmental http://dx.doi.org/10.1016/j.chemosphere.2015.04.102 0045-6535/Ó 2015 Elsevier Ltd. All rights reserved. and human safety (Corvaglia et al, 2008;Xu et al, 2011;Manzetti and Ghisi, 2014;Lee et al, 2014;Iliev et al, 2015;Jahne et al, 2015).…”