Prevalence of streptomycin-resistance genes in bacterial populations in European habitats

Abstract

The prevalence of selected streptomycin (Sm)-resistance genes, i.e. aph (3''), aph (6)-1d, aph (6)-1c, ant (3'') and ant (6), was assessed in a range of pristine as well as polluted European habitats. These habitats included bulk and rhizosphere soils, manure from farm animals, activated sludge from wastewater treatment plants and seawater. The methods employed included assessments of the prevalence of the genes in habitat-extracted DNA by PCR, followed by hybridisation with specific probes, Sm-resistant culturable bacteria and exogenous isolation of plasmids carrying Sm-resistance determinants. The direct DNA-based analysis showed that aph (6)-1d genes were most prevalent in the habitats examined. The presence of the other four Sm-modifying genes was demonstrated in 58% of the tested habitats. A small fraction of the bacterial isolates (8%) did not possess any of the selected Sm-modifying genes. These isolates were primarily obtained from activated sludge and manure. The presence of Sm-modifying genes in the isolates often coincided with the presence of IncP plasmids. Exogenous isolation demonstrated the presence of plasmids of 40-200 kb in size harbouring Sm-resistance genes from all the environments tested. Most plasmids were shown to carry the ant (3'') gene, often in combination with other Sm-resistance genes, such as aph (3'') and aph (6)-1d. The most commonly found Sm-modifying gene on mobile genetic elements was ant (3''). Multiple Sm-resistance genes on the same genetic elements appeared to be the rule rather than the exception. It is concluded that Sm-resistance genes are widespread in the environmental habitats studied and often occur on mobile genetic elements and ant (3'') was most often encountered.

Increased Abundance and Transferability of Resistance Genes after Field Application of Manure from Sulfadiazine-Treated Pigs

“…These resistance genes are often located on plasmids (11,12). Manure was shown to be a hot spot for bacteria carrying antibiotic resistance genes and mobile genetic elements (3,(13)(14)(15)(16)(17)(18) and may enhance the horizontal gene transfer of antibiotic resistance genes in soil (19), although it was shown that bacterial populations of manure and soil may be quite distinct (20). Additionally, nutrients provided by manure might stimulate the growth of bacteria in soil, increasing the effect of SDZ, which is active on growing cells (21,22).…”

Application of real-time PCR array to the multiple detection of antibiotic resistant genes in glacier ice samples

“…Horizontal gene transfer is a key phenomenon for antibiotic resistance genes to persist in a new environment (Van Elsas and Bailey, 2002). Indeed, the antibiotic resistance genes detected here have been reported to reside on the mobile genetic elements (Agerso et al, 2006;Bauernfeind et al, 1996;Bradford et al, 1997;Chopra and Roberts, 2001;Desomer et al, 1992;Furushita et al, 2003;Matsuoka et al, 1997;Nagy et al, 1997;Van Overbeek et al, 2002;Wohlleben et al, 1989).…”

Real-time PCR methods for quantitative monitoring of streptomycin and tetracycline resistance genes in agricultural ecosystems

“…Most previous studies investigating antibiotic resistance mechanisms in the environment have focused on the PCR detection of resistance genes (Binh et al, 2008(Binh et al, , 2009Heuer and Smalla, 2007;Nikolakopoulou et al, 2005;van Overbeek et al, 2002). Singleplex qPCR using SYBR green detection has previously been used to detect certain antibiotic resistance genes in environmental samples, most frequently identified in water or waste water samples (Volkmann et al, 2004(Volkmann et al, , 2007Borjesson et al, 2009;Knapp et al, 2008;Koike et al, 2007;Pruden et al, 2006;Smith et al, 2004).…”