Differential distribution of plasmid-mediated quinolone resistance genes in clinical enterobacteria with unusual phenotypes of quinolone susceptibility from Argentina.
Antimicrob Agents Chemother
; 57(6): 2467-75, 2013 Jun.
Article
em En
| MEDLINE
| ID: mdl-23478955
We studied a collection of 105 clinical enterobacteria with unusual phenotypes of quinolone susceptibility to analyze the occurrence of plasmid-mediated quinolone resistance (PMQR) and oqx genes and their implications for quinolone susceptibility. The oqxA and oqxB genes were found in 31/34 (91%) Klebsiella pneumoniae and 1/3 Klebsiella oxytoca isolates. However, the oqxA- and oqxB-harboring isolates lacking other known quinolone resistance determinants showed wide ranges of susceptibility to nalidixic acid and ciprofloxacin. Sixty of the 105 isolates (57%) harbored at least one PMQR gene [qnrB19, qnrB10, qnrB2, qnrB1, qnrS1, or aac(6')-Ib-cr)], belong to 8 enterobacterial species, and were disseminated throughout the country, and most of them were categorized as susceptible by the current clinical quinolone susceptibility breakpoints. We developed a disk diffusion-based method to improve the phenotypic detection of aac(6')-Ib-cr. The most common PMQR genes in our collection [qnrB19, qnrB10, and aac(6')-Ib-cr] were differentially distributed among enterobacterial species, and two different epidemiological settings were evident. First, the species associated with community-acquired infections (Salmonella spp. and Escherichia coli) mainly harbored qnrB19 (a unique PMQR gene) located in small ColE1-type plasmids that might constitute its natural reservoirs. qnrB19 was not associated with an extended-spectrum ß-lactamase phenotype. Second, the species associated with hospital-acquired infections (Enterobacter spp., Klebsiella spp., and Serratia marcescens) mainly harbored qnrB10 in ISCR1-containing class 1 integrons that may also have aac(6')-Ib-cr as a cassette within the variable region. These two PMQR genes were strongly associated with an extended-spectrum ß-lactamase phenotype. Therefore, this differential distribution of PMQR genes is strongly influenced by their linkage or lack of linkage to integrons.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Plasmídeos
/
Proteínas de Bactérias
/
Quinolonas
/
Farmacorresistência Bacteriana
/
Enterobacteriaceae
/
Antibacterianos
Limite:
Humans
País/Região como assunto:
America do sul
/
Argentina
Idioma:
En
Revista:
Antimicrob Agents Chemother
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Estados Unidos