Ama. Nascimento et al., Re-evaluation of antibiotic and mercury resistance in Escherichia coli populations isolated in 1978 from Amazonian rubber tree tappers and Indians, RES MICROB, 150(6), 1999, pp. 407-411
A study was carried out to assess the stability of antimicrobial susceptibi
lity of wild isolates upon long-term storage using fifty-three Escherichia
coli strains isolated in :1978 from feces of healthy children from the Amaz
on region in Brazil, exposed to low levels of antimicrobial agents, and exa
mined for resistance to mercury and four antibiotics. All of the strains we
re kept in Lignieres medium at room temperature and were transferred to fre
sh media four times during this period. Thirty-five out of the 53 strains a
nalyzed in 1978 were viable. Upon recovery, antibiotic and mercury resistan
ce was estimated. All of the 35 strains maintained their original phenotype
in a stable fashion, except for one multiresistant strain which became sus
ceptible to kanamycin. Fifty-four percent of the strains exhibited a resist
ance phenotype, among which 47% had conjugative plasmids. (C) Elsevier, Par
is.