出版社：Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul
摘要：The present work analysed the frequency of antimicrobial resistant enteric
bacteria in a sewage treatment plant in Porto Alegre (RS, Southern Brazil).
Water samples were collected every three months, from July/1997 to June /1998,
at the inflow, at the facultative stabilization lagoon, at the maturation lagoon
and the effluent of the plant. Two sites outside the plant (71a and 71b) were
also sampled. Antimicrobial resistance was determined by disc diffusion test on
Mueller-Hinton agar, where 18 different antimicrobials were tested. Among the
839 isolated strains, Enterobacter sp (n=348) and Escherichia coli (n=210) were
the most frequently observed ones, followed by Proteus sp (n=66), Serratia sp
(n=53), Citrobacter sp (n=40), Klebsiella sp (n=37), Yersinia sp (n=32),
Shigella sp (n=28) and Salmonella sp (n=25). The total number of bacteria and
antimicrobial resistant strains (rs) decreased from inflow (4.69x104cfu/mL;154
rs) to effluent (7.94x103 cfu/mL;49 rs) at the treatment plant. At sites 7a and
7b the number of resistant strains was as high as the inflow. The number of
multiresistant strains also reduced significantly from the inflow to the
effluent. The present study demonstrates that the sewage treatment system
investigated is efficient in decreasing enterobacteria and antimicrobial
resistant bacterial numbers, contributing to a lower discharge of multiresistant
bacteria into the environment.
