Molecular epidemiology of bacterial infectionsSunday, April 01, 2012, 13:30 - 14:30
First NDM-1-producing Acinetobacter baumannii in BelgiumR. Rezende de Castro*, P. Bogaerts, S. Roisin, A. Deplano, T. Huang, M. Hallin, O. Denis, Y. Glupczynski (Yvoir, Brussels, BE)
Objectives: To characterize the genetic environment of a NDM-1-producing Acinetobacter baumannii (Ab) isolated from a patient who was repatriated to Belgium from Algeria in 2011.
Methods: Antimicrobial susceptibility testing was performed by microdilution method according to CLSI guidelines. Resistance genes were characterized by PCR, DNA microarray (Check-points CT102) and sequencing. The genetic background of blaNDM-1 was analysed by PCR mapping. Transferability of beta-lactam resistance was tested by broth mating-out assays and transformation of plasmids. Typing of the Ab strain was performed by multilocus sequence typing (MLST).
Results: A multidrug and carbapenem-resistant Ab isolate 11314 was recovered from a rectal swab specimen of a 20-year old patient in vegetative state transferred from Algeria to Belgium after severe traffic injury. The isolate was highly resistant to all beta-lactams including meropenem and imipenem (MIC >= 32 mg/L), aminoglycosides (gentamicin, tobramycin and amikacin), and quinolone (ciprofloxacin) but it remained susceptible to colistin (MIC = 0.5 mg/L), and tigecycline (MIC < 0.25 mg/L). PCR/sequencing and Check-points micro-array revealed the presence of blaNDM-1 only. A single not typeable plasmid of 174 kb was detected but transfer experiments failed to demonstrate the presence of any carbapenem-resistant trait, suggesting that the blaNDM-1 was located on the chromosome. PCR-mapping revealed that blaNDM-1 was located between two direct repeat of ISAba125 element in a transposon similar to the one reported in Ab 161/07 isolated in Germany (Pfeifer et al., JAC 2011; Accession Nr HQ857107). By MLST, Ab 11314 presented an allele profile 1-3-3-2-2-7-3 corresponding to sequence type (ST) 92 (Bartual et al., JCM 2005), a ST already described in many different regions of the world (mostly in association with OXA-23-producing Ab strains). Sequencing analysis of the intrinsic blaOXA-51-like and blaADC genes showed that this strain harboured the blaOXA-64 and the blaADC-26, neither of which were preceded by ISAba1 nor ISAba125.
Conclusions: Here, we report for the first time an A. baumannii-producing NDM-1 isolated in Belgium belonging to ST92. The blaNDM-1 gene was located in a composite transposon structure composed of two copies of the insertion sequence ISAba125, very similar to the structure described for another A. baumannii strain (Ab 161/07) from Germany.