Examination of the Aerobic Microflora of Swine Feces and Stored Swine Manure

Abstract

Understanding antibiotic resistance in agricultural ecosystems is critical for determining the effects of subtherapeutic and therapeutic uses of antibiotics for domestic animals. This study was conducted to ascertain the relative levels of antibiotic resistance in the aerobic bacterial population to tetracycline, tylosin, and erythromycin. Swine feces and manure samples were plated onto various agar media with and without antibiotics and incubated at 37°C. Colonies were counted daily. Randomly selected colonies were isolated and characterized by 16S rRNA sequence analyses and additional antibiotic resistance and biochemical analyses. Colonies were recovered at levels of 10 to 10 CFU mL for swine slurry and 10 to 10 CFU g swine feces, approximately 100-fold lower than numbers obtained under anaerobic conditions. Addition of antibiotics to the media resulted in counts that were 60 to 80% of those in control media without added antibiotics. Polymerase chain reaction analyses for antibiotic resistance genes demonstrated the presence of a number of different resistance genes from the isolates. The recoverable aerobic microflora of swine feces and manure contain high percentages of antibiotic-resistant bacteria, which include both known and novel genera and species, and a variety of antibiotic resistance genes. Further analyses of these and additional isolates should provide additional information on these organisms as potential reservoirs of antibiotic resistance genes in these ecosystems.

Chemical Removal of Cu and Zn from Swine Feces before Soil Application

“…Besides chemical analysis, microbiota in swine feces and manure also were analyzed. For example, the microbial community was affected by heavy metals, such as Zn and Cd [8], and swine feces and manure contained high levels of antibiotic bacteria [17].…”

Antibiotics in Agroecosystems: Introduction to the Special Section

“…This special section contains five core review papers, 19 technical, review, and issues papers (Table 1), and a glossary of commonly used terms. The topics include the occurrence (Durso et al, 2016; McCall et al, 2016), detection (Wallace and Aga, 2016), dissemination (Hafner et al, 2016; Ruuskanen et al, 2016; Sura et al, 2016), fate (Amarakoon et al, 2016; Kulesza et al, 2016; Liu et al, 2016; Xu et al, 2016; Youngquist et al, 2016), plant uptake (Franklin et al, 2016; Kumar and Gupta, 2016), microbiology (Nordenholt et al, 2016; Roberts and Schwarz, 2016; Rothrock et al, 2016a; Whitehead and Cotta, 2016; Zwonitzer et al, 2016), and ecological risk (Subbiah et al, 2016) of antibiotics and/or antibiotic resistance in agroecosystems and surrounding natural areas. The antibiotic drugs, ARB, and ARGs discussed in this special section are predominantly associated with animal production but also include fruit and vegetable production, as well as those associated with the application of biosolids to agricultural lands.…”

Genome Sequence of a Novel Multiple-Antibiotic-Resistant Member of the Erysipelotrichaceae Family Isolated from a Swine Manure Storage Pit

“…This practice has come under intense scrutiny in the United States and worldwide due to the role it might have on the increased development of bacterial antibiotic resistance and potential impact on human health ( 1 ). Research in our laboratories has focused on the study of commensal microbial populations of swine feces and manure stored in underground pits in the Midwest United States, in order to better understand their role as potential reservoirs of antibiotic-resistant bacteria and genes ( 2 – 4 ). To further delineate the antibiotic-resistant populations of these ecosystems, strictly anaerobic bacterial strains were isolated on media containing tetracycline and/or erythromycin.…”