Prevalence, identification by a DNA microarray-based assay of human and food isolates Listeria spp. from Tunisia.
OBJECTIVE
We aimed at evaluating the prevalence of Listeria species isolated from food samples and characterizing food and human cases isolates.


METHODS
Between 2005 and 2007, one hundred food samples collected in the markets of Tunis were analysed in our study. Five strains of Listeria monocytogenes responsible for human listeriosis isolated in hospital of Tunis were included. Multiplex PCR serogrouping and pulsed field gel electrophoresis (PFGE) applying the enzyme AscI and ApaI were used for the characterization of isolates of L. monocytogenes. We have developed a rapid microarray-based assay to a reliable discrimination of species within the Listeria genus.


RESULTS
The prevalence of Listeria spp. in food samples was estimated at 14% by using classical biochemical identification. Two samples were assigned to L. monocytogenes and 12 to L. innocua. DNA microarray allowed unambiguous identification of Listeria species. Our results obtained by microarray-based assay were in accordance with the biochemical identification. The two food L. monocytogenes isolates were assigned to the PCR serogroup IIa (serovar 1/2a). Whereas human L. monocytogenes isolates were of PCR serogroup IVb, (serovars 4b). These isolates present a high similarity in PFGE. Food L. monocytogenes isolates were classified into two different pulsotypes. These pulsotypes were different from that of the five strains responsible for the human cases.


CONCLUSIONS
We confirmed the presence of Listeria spp. in variety of food samples in Tunis. Increased food and clinical surveillance must be taken into consideration in Tunisia to identify putative infections sources.
Laboratoire de microbiologie et biologie moléculaire, CNSTN, pôle technologique, 2020 Sidi Thabet, Tunisia. Electronic address: hmaiedfatma@yahoo.com.
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Hmaïed
Laboratoire de microbiologie et biologie moléculaire, CNSTN, pôle technologique, 2020 Sidi Thabet, Tunisia.
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Helel
Plateforme biopuces du génopôle, Insa, CNRS 5504, Inra 792, 135, avenue de Rangueil, 31077 Toulouse cedex 04, France.
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Le Berre
Plateforme biopuces du génopôle, Insa, CNRS 5504, Inra 792, 135, avenue de Rangueil, 31077 Toulouse cedex 04, France.
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JM
François
Institut Pasteur, French National Reference Centre and WHO Collaborating Centre for Listeria, 25-28, rue du Docteur-Roux, 75724 Paris cedex 15, France.
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Leclercq
Institut Pasteur, French National Reference Centre and WHO Collaborating Centre for Listeria, 25-28, rue du Docteur-Roux, 75724 Paris cedex 15, France.
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Lecuit
Laboratoire de bactériologie de l'hôpital d'enfant de Tunis-Bab Saadoun, 1006 Tunis, Tunisia.
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Smaoui
Laboratoire de bactériologie de l'hôpital d'enfant de Tunis-Bab Saadoun, 1006 Tunis, Tunisia.
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Kechrid
Unité de microbiologie et biomolécules actives, faculté de sciences, campus universitaire, 2092 Tunis, Tunisia.
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Boudabous
Laboratoire de microbiologie et biologie moléculaire, CNSTN, pôle technologique, 2020 Sidi Thabet, Tunisia.
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Barkallah
D000369:Aged, 80 and over; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques / Q000379:methods*; D002555:Cerebrospinal Fluid / Q000382:microbiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D004269:DNA, Bacterial / Q000032:analysis; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005399:Fishes / Q000382:microbiology; D005516:Food Microbiology; D005523:Food Supply / Q000592:standards; D005798:Genes, Bacterial; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008074:Lipoproteins / Q000235:genetics; D008087:Listeria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D008088:Listeriosis / Q000453:epidemiology / Q000382:microbiology*; D008297:Male; D008460:Meat / Q000382:microbiology; D020411:Oligonucleotide Array Sequence Analysis; D011247:Pregnancy; D015995:Prevalence; D012703:Serotyping; D014416:Tunisia / Q000453:epidemiology; D014504:Urban Health; D014774:Virulence / Q000235:genetics
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D008074:Lipoproteins; C116063:P60 protein, bacteria
Listeria monocytogenes; Microarray-based assay; PFGE; Puce à ADN; Tunis; iap