A novel OXA-10 like b-lactamase is present in different Enterobacteriaceae.

PORTO AYELÉN; MENDEZ EMILCE; AYALA JUAN; GUTKIND GABRIEL; DI CONZA JOSÉ

Chicago, EEUU

Congreso; 47th annual Interscience Conference on Antimicrobial Agents and Chemotherapy - ICAAC; 2007

ASAM

Background: Integrons are mobile genetic elements that are capable of integrate and excise resistance gene cassettes. Therefore, their presence allows the increase of antibiotic resistance in the bacteria. Class 1 integrons are the most disseminated and studied, due to the fact that this class is predominant in many species of gram-negative bacilli.Among all the b-lactamases gene cassettes found in integrons, the family of blaOXA are the most frecuently detected and the OXA-10-like enzymes (with expanded-spectrum activity) were frequently described in non-fermenting bacteria, like Pseudomonas aeruginosa.Methods: Three multiresistant clinical isolates of enterobacteria (Citrobacter freundii 14, Escherichia coli 112 and Enterobacter cloacae 153) were analyzed for the presence of class 1, 2 and 3 integrons. The variable regions (VRs) present in class 1 integrons were amplified by PCR, cloned in an appropiate vector and sequenced.Results: Class 1 and 2 integrons were detected in these three isolates. The sequence analysis of class 1 integron VRs showed the presence of the same gene cassettes: a new gene cassette blaOXA-10-like denominated blaOXA-101 (acc. nºAM412777) associated with an aminoglycoside modifying enzyme AacA4. Concordantly, the isolates present high resistance levels to the ¥â-lactam antibiotics, gentamicin and amikacin.Conclusions: We had detected a new gene cassette in the VR of a class 1 integron belonging to the blaOXA-10 group that would confer resistance to third generation cephalosporins and monobactams. In the three isolates studied we found the same arragement of gene cassettes. The description of these genes in three different enterobacteria species could be due to their location in highly mobile elements.