Evaluation of manometric respiration tests to assess the effects of veterinary antibiotics in soil

Abstract

Extensive use of antimicrobials in veterinary medicine results in environmental exposure. Of major concern are microbial effects; including effects on nutrient soil cycles and antibiotic resistance. There is a need to assess the effects of these compounds in the environment. The application of standardized guidelines is relevant in studying many compounds. However there is a lack of special test methods designed for antibiotics.We validate manometric test flasks using glucose and a recalcitrant herbicide. The suitability of these tests for studying antibacterial agents is then investigated using two target functions (aerobic biodegradation and carbon transformation). Compound stability is quantified using HPLC techniques.Effects on total soil respiration in the biodegradation test are immediate and differ significantly from background. We show that compounds do not function as substrates, so effects are due to other soil processes, correlate well to sorption characteristics and are not dose dependent. This test provides details of relative antimicrobial potency towards soil microorganisms and can be used to rank compounds. However the test does not provide details on the nature or extent of specific microbial effects. In contrast, the carbon transformation test is more specific and provides a reproducible indication of dose effect relationships, which is more suitable in assessing the effects of these compounds in the environment.Presently, standard guidelines do not take into account the normal input of antibiotics into soils via contaminated sludge or manure. This should be corrected in future guidelines as these inputs alter microbial composition, organic matter, ionic strength and pH affect sorption and overall impact the test results.

Effects of triclosan on soil microbial respiration

“…30, 2011 E. Butler et al redosing suggests that triclosan was being utilized as a substrate by microbes that are both resistant to triclosan toxicity and able to synthesize appropriate enzymes for triclosan degradation. Alternatively, the respiration stimulation could have been stress induced [32] or might have resulted, in part, from the mineralization of a toxicity-enhanced microbial necromass by remaining microbes [33,34]. The response of SIR to redosing is less clear and suggests that total microbial biomass may be reduced in some cases following redosing.…”

Changes in functional diversity of soil microbial community with addition of antibiotics sulfamethoxazole and chlortetracycline

“…Antibiotics are detected to have inhibition effects on soil microbial respiration activity, and the EC 50 values for oxytetracycline, tylosin, and sulfachloropyridazine are 50, 30, and 72 mg kg −1 dry soil, respectively (Vaclavik et al 2004). The EC 10 values to soil respiration are calculated to be 7 mg kg −1 for sulfamethoxazole (SMX), and less effect on soil respiration is found for chlortetracycline (CTC) (Liu et al 2009a).…”

Novel Approaches to Monitoring and Remediation of Veterinary Antibiotics in Soil and Water: A Review

“…Antibiotics are commonly presented in animal urine and feces due to their low absorption rates, therefore, these antibiotics and their metabolites often show up in manure (Halling-Sorensen et al, 2002;Aga et al, 2003;Vaclavik et al, 2004). Veterinary antibiotics can also enter the environment through landfill and manure application, after which they are transported to surface water, sediments and finally groundwater (Fig.…”

“…Antibiotics, which are classified as active pharmaceutical ingredients (APIs), consist semi-synthetic or synthetic molecules with the ionic nature that have antimicrobial activity and are applied parentally, orally or topically (Kemper, 2008;Kümmerer, 2008). However, only 10-20% of the antibiotics applied to animals are likely to be utilized, while the rest are excreted through the urine or feces (Connor, 2004) which is being released into the environment (Montforts et al, 1999;Tolls, 2001;Winckler and Grafe, 2001;Boxall et al, 2002;Halling-Sorensen et al, 2002;Aga et al, 2003;Vaclavik et al, 2004). Furthermore, antibiotic resistance of bacteria becomes problematic when it leads to therapeutic failure or the need to overuse more toxic drugs because of increasing frequency, duration or severity of infection (Barza, 2002).…”