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Dispersion of Class 1 Integrase-like genes from environmental samples and its role as reservoirs of antimicrobial resistance Cassettes.
MARIA SOLEDAD RAMÍREZ; NELDA OLIVERA; J. DEGROSSI; DANIELA CENTRON
Congreso; 106th ASM General Meeting; 2006
American Society for Microbiology
Resistant bacteria have been isolated from a different number of sources, also including natural environment. A few groups have searched for the presence of integrons and gene cassettes in environmental samples. The recovery of new environmental integrons is consistent with the hypothesis that integrons are ancient structures and a common feature of bacterial populations. We have performed a field work with Parques Nacionales from Argentina in a frame of a CONICET grant for isolating environmental samples from pristine areas and we have also collected samples from different environmental sources in contact with human as industries, sewage and still water during the period between January 2004 and January 2005. Up to date we have a collection of gram negative bacilli from Patagonians lakes and rivers (n= 23), from Isla de los Estados (n=20), from Puerto Madryn (n=3), from contaminated water from Rio de La Plata (n= 5), from Ushuaia´s coast (n= 4), from Antarctica (n=2), from industries and sewage (n= 19) and plants pathogens bacterias (n= 7) from the province of La Pampa, Argentina. Currently the species that we have in our environmental collection of gram negative bacilli are Pseudomonas spp., Shewanella spp., Agrobacterium tumefaciens, Colwellia spp., Pseudoalteromonas spp., Planococcus spp., Bacillus spp, Rhizobium spp., Sinorhizobium spp., Bradyrhizobium spp., Formosa spp., , and Alcaligenes spp. We have looked for the presence of class 1 integrase-like genes and gene cassettes using specific primers and degenerate primers. We found that 33,3% (9/27) of the Patagonians isolates harbored class 1 integrase-like genes and that a 42,9% (3/7) of the plants pathogens bacterias were positive for the class 1 integrase. In the industries and sewage isolates we found a highest dispersion of the integrase gene (68,4%,13/19), correlating with a contaminated environment. Our results are negative for the presence of class 1 integrase-like genes in all bacterial isolates from the Isla de los Estados, every bacteria from contaminated water from Rio de La Plata and for the two Antartida´s isolates, but we found amplification products when we used degenerate primers for the screening of gene cassette. Further investigations are needed to elucidate the role of these integrons as reservoirs of antimicrobial resistance cassettes.