Open AccessChromate‐resistance genes in plasmids from antibiotic‐resistant nosocomial enterobacterial isolates
Author(s) -
CaballeroFlores Gustavo G.,
AcostaNavarrete Yaned M.,
RamírezDíaz Martha I.,
SilvaSánchez Jesús,
Cervantes Carlos
Publication year - 2012
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2011.02473.x
Subject(s) - plasmid , microbiology and biotechnology , antibiotics , antibiotic resistance , biology , gene , genetics
The presence of chromate‐resistance genes in enterobacteria was evaluated in a collection of 109 antibiotic‐resistant nosocomial isolates from nine major cities in México. Results were compared with the presence of mercury‐resistance genes. Susceptibility tests showed that 21% of the isolates were resistant to chromate ( Cr R ), whereas 36% were resistant to mercury ( Hg R ). Cr R levels were high in K lebsiella pneumoniae (61%), low in E nterobacter cloacae (12%) and E scherichia coli (4%), and null in S almonella sp. isolates. Colony hybridization demonstrated that the majority of metal‐resistant isolates hybridized with chrA gene (87% of Cr R isolates), encoding a CHR transporter homologue, and merA gene (74% of Hg R isolates), encoding MerA mercuric reductase, suggesting that most isolates expressed these widespread metal‐resistance systems. Southern blot hybridization of Cr R isolates showed that plasmids of 80, 85, and 95 kb from K . pneumoniae isolates, and of 100 kb from an E . cloacae isolate, contained chrA ‐related sequences. These plasmids belonged to IncN or IncP incompatibility groups, and conferred Cr R , as well as multiple antibiotic resistance, when transferred by conjugation to an E . coli standard strain. These data indicated that Cr R genes may be distributed among clinical enterobacteria via conjugative plasmids, probably by coselection with antibiotic‐resistant genes.