Multidrug resistance in Salmonella isolates recovered from different food sources in Colombia

Abstract number: O561

Martins M., Karczmarczyk M., McCusker M., Mattar S., Amaral L., Fanning S.

Objectives:Salmonella enterica is the most common etiological agent of food borne salmonellosis worldwide. Ciprofloxacin is the antibiotic of choice for the treatment of these infections. Until date, fluoroquinolone resistance remains uncommon in this bacterium. However, the incidence of nalidixic acid resistance is increasing with isolates showing decreased susceptibility to fluoroquinolones. We have screened a large collection of Salmonella strains to determine the incidence of multi-drug resistance (MDR) and to further characterize the genotypic and phenotypic mechanisms that contribute to this MDR.

Methods: From 2002–2009, 93 Salmonella strains from Colombian foods and exotic animals were obtained from the University of Cordoba (Colombia). The serovar and the susceptibility profile of each strain were determined. Antibiotics representative of 8 different classes were tested and strains that demonstrated resistance to nalidixic acid (NA) were further characterized. PCR was performed to determine the presence of qnr genes. Additionally, efflux activity was evaluated by the EtBr-agar cartwheel method. Ex vivo studies were conducted to assess potential differences on the infection and adherence ability of the isolates.

Results: The most predominant serovars in these isolates were: Uganda (n = 19), Anatum (n = 14), Newport (n = 11) and Braenderup (n = 10); although in total 19 different serovars were obtained. Thirteen isolates were resistant to NA (and/or other antibiotics). Four strains showed increased efflux activity when compared with the controls. This was further confirmed by determining the minimum inhibitory concentration of NA in the presence of the efflux pump inhibitor: phenylalanine-arginine-b-napthylamide (PAbN). Resistance to quinolones was confirmed by PCR through the identification of the qnrB19 gene that confers low-level resistance to this class of antibiotics. Ex vivo assays were useful to clarify the infection and adherence potential of the isolates.

Conclusion: In this study, a large collection of Salmonella isolates obtained from food and exotic animals were resistant to NA and/or other class of antibiotics. These isolates showed different serovars and increased efflux activity along with the presence of the qnrB19 gene. The ex vivo assays contributed to clarify the infection and adherence potential of the isolates. These data highlight the importance of intrinsic and acquired mechanisms of MDR in Salmonella.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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