[Transference of extended-spectrum beta-lactamases from nosocomial strains of Klebsiella pneumoniae to other species of Enterobacteriaceae].
BACKGROUND
Klebsiella pneumoniae is an important pathogenic bacterium, frequently isolated from nosocomial samples, that exhibits wide antimicrobial resistance profiles, including third generation cephalosporins (3GC), aminoglycosides and quinolones. The resistance to 3GC is mainly due to the synthesis of extended spectrum beta lactamases (ESBL), encoded by conjugative plasmids.


OBJECTIVE
To investigate the potential transference of resistance to 3GC from nosocomial strains of K. pneumoniae to other clinical strains of various species of Enterobacteriaceae.


METHODS
The mating experiments were carried out in liquid media and three nosocomial strains of K. pneumoniae were used as donors. These strains were ESBL-producers and resistant to, at least, one of the 3GC assayed. One strain of Citrobacter freundii, Salmonella typhimurium, Serratia marcescens and Escherichia coli, isolated from clinical specimens, were used as recipients. The presence of bla genes was investigated by PCR.


RESULTS
The three nosocomial strains of K. pneumoniae were able to transfer the resistance to 3GC and the genes encoding the ESBL to the susceptible recipient strains of enterobacteria. The frequency of transference was as high as 3.2 x 10-2 transconjugants/recipient cell when the strain of Citrobacter freundii was used as recipient. All transconjugants exhibited high level of resistance to the 3GC assayed.


CONCLUSIONS
Strains of K. pneumoniae isolated from Chilean hospitals are able to disseminate the ESBL genes to clinical strains of others species of Enterobacteriaaceae.
Sánchez U
Magaly
M
Grupo de Investigación en Resistencia a Antibióticos, Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile.
Bello T
Helia
H
Domínguez Y
Mariana
M
Mella M
Sergio
S
Zemelman Z
Raúl
R
González R
Gerardo
G
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018550:Cephalosporin Resistance / Q000235:genetics*; D002511:Cephalosporins / Q000494:pharmacology*; D016971:Citrobacter freundii / Q000187:drug effects / Q000201:enzymology; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012486:Salmonella typhimurium / Q000187:drug effects / Q000201:enzymology; D012706:Serratia marcescens / Q000187:drug effects / Q000201:enzymology; D014169:Transformation, Bacterial / Q000235:genetics*; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D001618:beta-Lactamases