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Turki Y.,Water Research And Technology Center Certe | Ouzari H.,University of Tunis | Mehri I.,Water Research And Technology Center Certe | Ben Aissa R.,Linstitut Pasteur Of Tunis | And 2 more authors.
Food Research International | Year: 2012

Food-borne diseases caused by Salmonella enterica are a significant public health concern around the world. Since 2002, S. enterica serovar Kentucky has shown an increase in several countries with the concurrent emergence of multidrug-resistant isolates. The spread of such strains in the environment poses a major public health problem. A total of 57 Salmonella Kentucky strains isolated from different sources during the period 2005 to 2008 in Tunisia, were characterized by their antimicrobial and mercury resistance profiles; ability to form a biofilm; virulence invA/spvC genes and quorum sensing sdiA gene. A total of 10.6% of the isolates demonstrated multidrug-resistance against 3 to 13 antibiotics with ciprofloxacin resistance occurring in 33% of human isolates. In addition, 37% of the isolates exhibited minimum inhibitory concentrations value to mercuric chloride, ranging from 8 to 32μgml -1 and were considered as resistant strains. The majority of strains tested were able to form a biofilm, especially for environmental and animal derived isolates. Therefore, the biofilm seems to comprise a normal and favorable capability in the life of Salmonella Kentucky in the environment. Interestingly, all the isolates possessed the sdiA gene, 87.7% of isolates possessed the invA gene, and no isolate harbored the spvC gene. The emergence of resistance to ciprofloxacin in human Salmonella Kentucky isolates, added to the presence of invA and sdiA genes, and the production of biofilm could be the decisive factors in the dissemination of S. Kentucky strains on a large scale. © 2011 Elsevier Ltd.


Turki Y.,Water Research And Technology Center Certe | Mehri I.,Water Research And Technology Center Certe | Ouzari H.,University of Tunis | Khessairi A.,Water Research And Technology Center Certe | Hassen A.,Water Research And Technology Center Certe
Journal of General and Applied Microbiology | Year: 2011

Salmonella enterica isolates representing commonly isolated serotypes in Tunisia were analyzed using genotyping and phenotyping methods. ERIC and ITS-PCR applied to 48 Salmonella spp. isolates revealed the presence of 12 and 10 different profiles, respectively. The distribution of profiles among serotypes demonstrated the presence of strains showing an identical fingerprinting pattern. All Salmonella strains used in this study were positive for the sdiA gene. Three Salmonella isolates belonging to serotypes Anatum, Enteritidis and Amsterdam were negative for the invA gene. The spvC gene was detected in thirteen isolates belonging to serotypes Anatum, Typhimurium, Enteritidis, Gallinarum and Montevideo. Antibiotic resistance was frequent among the recovered Salmonella isolates belonging to serotypes Anatum, Typhimurium, Enteritidis, Zanzibar and Derby. The majority of these isolates exhibited resistance to at least two antibiotic families. Four multidrug-resistant isolates were recovered from food animals and poultry products. These isolates exhibited not only resistance to tetracycline, sulphonamides, and ampicillin, but also have shown resistance to fluoroquinolones. Common resistance to nalidixic acid, ciprofloxacin and ofloxacin in two S. Anatum and S. Zanzibar strains isolated from raw meat and poultry was also obtained. Furthermore, wastewater and human isolates exhibited frequent resistance to nalidixic acid and tetracycline. Of all isolates, 33.5% were able to form biofilm. © 2014 Applied Microbiology, Molecular and Cellular Biosciences Research Foundation.


Turki Y.,Water Research And Technology Center Certe | Ouzari H.,University of Tunis | Mehri I.,Water Research And Technology Center Certe | Ammar A.B.,Unite des services communs pour la recherche en microscopie electronique a transmission | Hassen A.,Water Research And Technology Center Certe
Food Research International | Year: 2012

Salmonella serovars are increasing in importance as significant pathogens of both human and animals. Although water and wastewater are treated to eliminate pathogenic microorganisms, they still play an important role in the transmission of Salmonella spp. In this study, bacteriophages infecting Salmonella spp. were isolated from wastewater and evaluated; for their potential to lyse environmental Salmonella strains in vitro at different MOIs and temperatures; and to control the wastewater bacterial community. Three distinct phages designated sww65, sww275, and sww297; as defined by plaque morphology, electron microscopy and host range; were obtained from wastewater. Challenge tests were performed at 37, and 30°C with the infection of the Salmonella cultures with individual phage, a mixture of two phages, and cocktail of three phages at MOIs of 10 0, 10 2, and 10 4 PFU/CFU. At 30, and 37°C, a cocktail of three phages reduced all of the Salmonella cultures tested. These results required a high multiplicity of infection. However, when infected with only one phage or a mixture of two phages at MOIs of 10 0 or 10 2 PFU/CFU, an emergence of bacterial resistance was observed. The dynamic monitoring of wastewater enterobacterial community was conducted using Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR). The number of bands decreased gradually with the use of individual phage or phage cocktails. Moreover, the dynamic monitoring of Salmonella community during wastewater treatment was performed using PCR detection of virulence gene invA. The results correlated with the ERIC-PCR fingerprints, and suggested that Salmonella community was affected by the phage treatment. Indeed, in wastewater, bacteriophages are reducing Salmonella and other members of the Enterobacteriaceae. These results indicated that dynamic changes are closely related with the process of treatment. The introduction of wide host range bacteriophages in wastewater can have a potential impact on the dynamics of the microbial communities, manifested by the reduction or the elimination of microbial species. © 2011 Elsevier Ltd.

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