IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Transferable Quinolone Resistance (TQR) in Enterobacteria from Argentina: aac(6)-Ib-cr and a Novel qnrB Allele (qnrB6) are Located in a Complex Class 1 Integron
Autor/es:
A. PETRONI, P. ANDRÉS, A. SOLER BISTUÉ, P. QUIROGA, A. ZORREGUIETA, D. CENTRÓN, M. GALAS
Lugar:
Chicago USA
Reunión:
Congreso; 47th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC); 2007
Institución organizadora:
American Society for Microbiology
Resumen:
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Background: The worldwide emergence of TQR is becoming one of the major threats
in bacterial resistance. In Argentina, TQR was not reported yet.
Methods: The multiresistant (MR) Klebsiella
pneumoniae (Kpn) M7943 was isolated from a blood culture (Buenos Aires, 2006).
Escherichia coli J53 azide-resistant
(AzR) was the recipient strain in conjugative assays. MICs were determined by the
agar dilution method (CLSI). Conjugations, PCR and DNA sequencing were
performed by standard methods. Long PCR conditions were used for fragments >
4 kb.
Results: An ISCR1-containing class 1 integron, named
InK122 (approx. 15 kb), was found in Kpn M7943 and was transferred by
conjugation to E. coli J53 AzR, rendering transconjugant M7943-Tc. Relevant
susceptibility profiles of Kpn M7943 and E.
coli M7943-Tc were, respectively (MIC, µg/ml): nalidixic acid, 128/16;
ciprofloxacin, 32/2; levofloxacin, 4/0.5; amikacin, 16/4; tobramycin, 16/16. InK122
showed a 4-cassettes variable region: aac(6)-Ib-cr,
blaOXA-30, catB3 and arr-3. This region was 96% identical to that of In37 [differences
were mainly at the 5 ends of the aac(6)-Ib-cr
genes]. InK122 harbored the novel qnrB6
allele, in a 5,401-bp region located between ISCR1 and a second copy of the 3conserved sequence. This region
contained a sap-like operon (sapC, B and A), qnrB6, and a portion of a psp-like operon (pspF), that are transcribed antisense to ISCR1. The
deduced QnrB6 protein (226 amino acids) had 98% identity with QnrB5. The same qnrB6-containing region was found in 7
independent MR clinical isolates from Buenos Aires (2005), 2 Citrobacter freundii and 5 Enterobacter spp.
Conclusions: Both aac(6)-Ib-cr- and qnr-mediated TQR were
identified in Argentina. A national surveillance is essential to estimate the prevalence
of these mechanisms.
Category: C1
Keywords: Klebsiella pneumoniae; quinolone resistance;
integron
Control/Tracking Number: ICAAC07-A-2215-ASM