C.I. Lima-Bittencourt¹, L. Cursino¹, H. Gonçalves-Dornelas¹, D.S. Pontes¹, R.M.D. Nardi², M. Callisto¹, E. Chartone-Souza¹ and A.M.A. Nascimento<sup>1

1</sup>Departamento de Biologia Geral, ²Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
Corresponding author: A.M.A. Nascimento
E-mail: amaral@ufmg.br

Genet. Mol. Res. 6 (3): 510-521 (2007)
Received June 13, 2007
Accepted July 30, 2007
Published September 5, 2007

ABSTRACT. A freshwater enterobacterial population (N = 111) was studied for antimicrobial and mercury resistance patterns, and for its possible association with biotic and abiotic factors in that environment. Conventional biochemical tests identified Klebsiella sp, Morganella sp, Serratia sp, Escherichia sp, Enterobacter sp, Edwarsiella sp, Proteus sp, Citrobacter sp, Providencia sp, and Kluyvera sp. There was no correlation between antimicrobial resistance patterns of isolates and bacterial genera, but resistance patterns varied among water samples and between seasons. Resistance to multiple antimicrobials was common (61%). The percentage of bacteria resistant to at least one antimicrobial differed between the rainy (100%) and dry seasons (89%). Resistance to β-lactams and chloramphenicol was the most frequent and resistance to amikacin, gentamicin and kanamycin was less frequent. The main water variables examined (abiotic factors pH and temperature; biotic factor chlorophyll a concentration) did not influence antimicrobial resistance. Significant impact on freshwater enterobacteria, as evidenced by antimicrobial-multiple resistance and by the presence of bla_TEM gene, may point to the fact that it has an important role in horizontal spread of resistance.

Key words: Abiotic factors, Antibiotic resistance, Enterobacteriaceae, Freshwater, Mercury