Transferable fluoroquinolone resistance in Enterobacteriaceae and Pseudomonas aeruginosa isolated from hemocultures.
BACKGROUND
The main mechanisms causing high-level resistance to fluoroquinolones (FQ) are encoded chromosomally; that includes mutations in genes coding DNA-gyrase, but overexpression of efflux pumps contributes to increased minimum inhibitory concentration (MIC) of FQ as well. However, genes responsible for FQ-resistance may be harboured in transferable/conjugative plasmids. For some time, there was an assumption that resistance to FQ cannot be transferable in conjugation due to their synthetic origin, until 1998, when plasmid-mediated resistance transmission in Klebsiella pneumoniae was proved. We aimed to detect the occurrence of transferable FQ-resistance among Gram- negative bacteria isolated from patients in Czech and Slovak hospitals.


METHODS
In this study, we tested 236 clinical isolates of Gram-negative bacteria for transferable resistance. Among relevant isolates we performed PCR detection of transferable fluoroquinolone genes (qnr).


RESULTS
We have observed transfer of determinants of cephalosporin-resistance, aminoglycoside resistance as well as FQ-resistance (in 10 cases; 4.24%) not only intra-species but inter-species too. The presence of qnr gene was detected in two isolates of forty tested (5%). We have also observed that determinants of cephalosporin-resistance and aminoglycoside-resistance were linked to those of FQ-resistance and were transferred en block in conjugation.


CONCLUSIONS
We have proved that resistance to fluoroquinolones can be transferred horizontally via conjugation among Gram-negative bacteria of different species and is associated with resistance to other antibiotics.
Nada
N
Kulková
Marta
M
Babálová
Jaroslava
J
Brnová
Vladimír
V
Krcméry
D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D018153:Czech Republic; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects* / Q000235:genetics; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000302:isolation & purification; D024841:Fluoroquinolones / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D016133:Polymerase Chain Reaction; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D018154:Slovakia
D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones