Detection and characterization of class 1 integrons in Aeromonas spp. isolated from human diarrheic stool in Mexico

Abstract

We determined the presence of class 1 integrons related to the acquisition of resistance to antimicrobials in Aeromonas spp. isolated from individuals with diarrhea. Species were identified as A. caviae, A. hydrophila, A. veronii and A. media using PCR-RFLP of the 16S rDNA. Selected isolates were further characterized by ERIC-PCR. Resistance to chloramphenicol, aztreonam, tetracycline, trimethoprim/sulfamethoxazole, nalidixic acid and streptomycin, among others, was determined using the Kirby-Bauer method. Integrons were detected by PCR amplification of the 5' conserved, variable, and 3' conserved regions. Sequencing of the variable regions revealed class 1 integrons with cassettes encoding resistance to trimethoprim (dfrA12, dfrA15, dfrB4), streptomycin/spectinomycin (aadA2, aadA1), oxacillin (oxa2) and chloramphenicol (catB3, cmlA4). Others had an open reading frame (orfD) or no insert at all. To our knowledge, this is the first description of the occurrence of genes cmlA4 and dfrA15 in Aeromonas class 1 integrons. Not all the integron-linked cassettes conferred their associated resistances, which suggests the inactivity of some cassettes. Most integrons were chromosomally located. The presence of class 1 integrons similar to those found in a wide variety of bacterial genera from different origins, including environmental and fish-borne Aeromonas, confirms the stability and horizontal transfer of these genetic elements.

Detection of antibiotic resistance, virulence gene determinants and biofilm formation in Aeromonas species isolated from cattle

“…isolated from rainbow trout farms in Australia (Ndi and Barton 2011). However, the incidence of class 1 integrons in clinical samples has been documented by Pérez-Valdespino et al (2009), and there is a significant amount of information on class 1 integrons in animal faeces. Furthermore, the identification of class 1 and 2 integrase genes in mixed bacterial cultures enriched from bovine faeces has been previously documented (Barlow et al 2004).…”

Antibiotic Susceptibility Profile ofAeromonasSpecies Isolated from Wastewater Treatment Plant

“…Tetracycline resistance has been reported in Aeromonas species isolated from a river that receives wastewater discharge [25]. Similarly, Aeromonas hydrophila , Aeromonas caviae , and Aeromonas veronii isolated from human diarrhoeic stool in Mexico [26] showed variable resistances to tetracycline. Jacobs and Chenia [27] also observed high resistance to tetracycline in Aeromonas species from aquaculture system in South Africa.…”

“…The detection of class 1 integron may be attributed to a wide spread distribution of class 1 integron in Gram-negative microorganism. Pérez-Valdespino et al [26] reported presence of class 1 integron in Aeromonas species isolated from patient with diarrhoea in Mexico and found it had association with the acquisition of resistance to antimicrobials in Aeromonas species. The presence of class1 and 2 integron in Aeromonas and Enterobacteriaceae in Portugal was also reported [30, 31]; however higher prevalence of class 1 integron was found in final effluent [30, 31].…”

Class 1 Integrons in <i>Aeromonas hydrophila</i> Isolates from Farmed Nile Tilapia (<i>Oreochromis nilotica</i>)

“…The resistance gene cassette aadA2 was previously described in Aeromonas spp. from humans in Mexico [32], Aeromonas spp. from rainbow trout in Australia [29], V. cholerae from human and environmental samples in Thailand [9] and S. enterica from food in Portugal [2].…”

“…Class 1 integrons is the most common integron type identified among resistant bacteria [32]. The elements could be horizontally transferred among bacteria inter-and intra-species and play an important role in the acquired resistance among Gram-negative bacteria [15].…”