PRESENCE OF BLA_TEM-116 GENE IN ENVIRONMENTAL ISOLATES OF AEROMONAS HYDROPHILA AND AEROMONAS JANDAEI FROM BRAZIL

Livia Balsalobre (FSP-USP); Milena Dropa (FSP-USP); Danielle Escudeiro (FSP-USP); Nilton Lincopan (FCF-USP); Elsa Mamizuka (FCF-USP); Glavur Rogério Matté (FSP-USP); Maria Helena Matté (FSP-USP)

Members of the genus Aeromonas have been associated with a wide range of illnesses in humans, including gastrointestinal disorders and systemic infections in both immunocompromised and healthy hosts. Several studies have shown the presence of Aeromonas spp. in food and drinking water samples, suggesting that these sources may act as dissemination vehicles of the human pathogen, with implications in the public health. Furthermore, it is known that Aeromonas spp. are among the few microorganisms harboring different chromosomal beta-lactamase genes, including cphA (also named imiH), cepH and ampH, encoding class B, C and D beta-lactamases, respectively. The aim of this study was to investigate the presence and phenotypic expression of bla_TEM, bla_SHV, and bla_CTX-M ESBL-encoding genes in 87 environmental water isolates of Aeromonas hydrophila (n=41) and Aeromonas jandaei (n=46). The identification of Aeromonas species was performed as previously described. All isolates were screened for ESBL production by a synergy test using clavulanic acid (amoxicillin-clavulanate disk, 20/10 µg) and cloxacillin (200 µg/ml-containing Mueller-Hinton agar plates) as ESBL and AmpC inhibitors, respectively, and ceftazidime, cefpodoxime and cefotaxime-containing disks as ESBL substrates. Presence of ESBL-encoding genes was evaluated by PCR, and plasmid extraction was carried out using the commercial kit Wizard Plus SV Miniprep (Promega-USA). Also the search for class 1 integron was carried out according to previous literature. Although production of ESBL was not confirmed by phenotypic methods, and no amplification of the bla_SHV and bla_CTX-M genes was observed, the presence of the bla_TEM gene was verified in 97.6% (40/41) and 85% (39/46) of A. hydrophila and A. jandaei isolates, respectively. Nucleotide sequencing showed 100% sequence identity with the bla_TEM-116 gene (GenBank accession numbers FJ767900 to FJ767909). Plasmids were found in 24.4% (10/41) of A. hydrophila and in 34.9% (16/46) of A. jandaei isolates, suggesting no association between plasmid occurrence and presence of bla_TEM genes. Also, the association of bla_TEM genes with the occurrence of class 1 integrons was not observed.