A NOVEL ST 1606 IN EXTENSIVELY DRUG-RESISTANT Acinetobacter baumannii CARRYING PLASMID-MEDIATED RESISTANCE GENES ISOLATED FROM BRAZILIAN SOIL

Acinetobacter baumannii is a non-ferminating Gram-negative bacilli widely distributed in the environment. A. baumannii emerges as the major opportunistic pathogen and has been commonly reported in different types of infections, mainly in immunocompromised patients. Different antimicrobials can be used to treat infections caused by this pathogen; however, this bacterium may possess different associated resistance mechanisms, for which it becomes non-susceptible. Here we reported a novel ST 1606 in an extensively drug-resistant (XDR) A. baumannii harboring different plasmid-mediated resistance genes isolated from the Brazilian soil. Soil samples from different plantation areas and from several cities of Brazil were used for bacterial isolation using MacConkey agar. The genomic DNA was extracted and it was used for sequencing of the 16S rRNA and 23S rRNA genes and for the amplification of the bla OXA-51-like. The resistance profile was performed using the disk diffusion and minimal inhibitory concentration methods. PCR reactions were performed for detection of several plasmid-mediated resistance genes and integrons. MLST analysis was performed using specific primers described in the A. baumannii MLST database. The plasmid was extracted and the molecular weight was calculated. An A. baumannii isolate named S402 was obtained from a soil sample cultivated with corn in Ribeirão Preto City, São Paulo State, Brazil. This isolate was non-susceptible to almost all recommended antimicrobials, except for tetracyclines (doxycycline and minocycline) and fluoroquinolones (ciprofloxacin and levofloxacin), being thus classified as XDR. The isolate S402 presented bla SHV, bla GES , bla CTX-M-Gp9 , aac(6')-Ib, aph(3')-Ia, tetB and intI1 genes. This isolate presented only one high molecular weight plasmid with ~ 310 Kb. MLST analysis showed five new alleles gdhB (183), gyrB (176), gltA (allele 111), cpn60 (113) and recA (118) and two alleles already described rpoD (129) and gpi (132), which generated the new ST 1606. The set of plasmid-mediated resistance genes found in the isolate S402 is closely related to the XDR phenotype. These results indicate that A. baumannii isolated from soil harbor different plasmid-mediated resistance genes, which they can be transferred to different bacterial genera. The detection of several plasmid-mediated resistance genes is of great concern, since it suggests that the environment is a great reservoir of these genes.