The Impact of Environmental Contamination with Antibiotics on Levels of Resistance in Soil Bacteria

Abstract

This study examined the effects of tetracycline and streptomycin on microorganisms in three different soil habitats: forest soil, agricultural soil, and compost. These antibiotics are commonly used in both medical and veterinary therapy as well as in the production of plant biomass and until quite recently, the production of animal biomass. Microcosms were used as model systems in which the number of microorganisms in environments containing different amounts of antibiotics was analyzed. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of tetracycline and streptomycin were determined. The MIC and MBC values of tetracycline against the tested strains were 20 to 180 microg/ mL and 30 to 300 microg/mL, respectively, and of streptomycin, 360 to 500 microg/mL and > or =500 microg/mL, respectively. Resistant bacterial strains were identified and their physiological profiles assessed. Streptomycin and tetracycline were found to reduce the number of bacteria in the studied soils by between 50 and 80%. Soil bacteria were found to be more resistant to streptomycin than to tetracycline. The bacterial species showing the highest resistance to tetracycline were Rhizobium radiobacter, Burkholderia cepacia, Brevundimonas vesicularis, and Pasteurella multocida. Most soils with high concentrations of streptomycin (5 mg/kg) contained Rhizobium radiobacter, Burkholderia cepacia, and Sphingomonas multivorum, among others. The strains most resistant to tetracycline were isolated from agricultural soil that is constantly subjected to tetracycline pressure from animal manures and biosolids. Among resistant strains, opportunistic pathogens were identified.

An assessment of antibiotic resistant bacteria in poultry litter and agricultural soils in Kandy district, Sri Lanka

“…Spreading of ARB with higher MIC and MBC values in the environment is a threat for public health (Laxminarayanv et al, 2013;Popowska et al, 2012). The reason for existence of innate resistance towards an antibiotic is a permanent genetically determined character of a bacterial species (Popowska et al, 2010). Bacteria have different mechanisms to resist antibiotics (Nesme and Simone, 2015) hence, a large diversity could be expected among studied ARB populations.…”

Influence of Soil Use on Prevalence of Tetracycline, Streptomycin, and Erythromycin Resistance and Associated Resistance Genes

“…Degradation rates in soil are particularly dependent upon antibiotic properties (molecular structure and chemical and physical properties), edaphic properties (pH, minerals, and organic matter), and/or other conditions (temperature, aerobicity, adsorption, and absorption). Residual antibiotics can affect the soil microbiome, resulting in differential inhibition of certain microorganisms and in perturbations in community composition (11,12,18,44,45,48). The increasing use of antibiotics in medicine, veterinary medicine, and agricultural production systems has coincided with increasing development of high levels of antibiotic resistance and novel antibiotic resistances (1,2,3,4,32,53).…”

Diversity of Antibiotic Resistance Among Bacteria Isolated from Sediments and Water of Carp Farms Located in a Polish Nature Reserve

“…The most probable number (MPN) method was used to determine the CFU/mL of ammonifying, nitrifying, denitrifying, and sulfate-reducing bacteria [35]. The number of amylolytic, proteolytic, lipolytic, ammonifying, nitrifying, denitrifying, and sulfate-reducing bacteria and actinomycetes was determined using specific media, as described previously [32]. Liquid cultures or plates were incubated at 26ºC for three days (proteolytic, amylolytic, and ammonifying bacteria), seven days (actinomycetes, denitrifying, lipolytic, and sulfate-reducing bacteria), or 14 days (nitrifying bacteria).…”

“…The resistance to streptomycin and tetracycline was significantly lower in aquatic Pseudomonas isolates (29%, n = 2 and 14%, n = 1 respectively) than in sedimentary strains of this genus (57%, n = 4 and 43%, n = 3). Stenotrophomonas strains that were isolated mainly from the water were also characterized by a very high level of resistance to tetracycline (90%, n = 9) and high resistance to streptomycin (60%, (30), tet (32) str Table 6. Characteristics of antibiotic-resistant bacteria isolated from fish pond water.…”

“…Tetracycline degrades by 24% within 10 to 180 days and erythromycin by 25% within 30 days, while streptomycin is not degraded up to 30 days after environmental release [20]. Residual antibiotics can affect the composition of the soil and water microbiome [31][32].…”