Archives de l'Institut Pasteur de Tunis最新文献

The anti-sandflies and, insecticides impregnated collars are actually mentioned as the main mean for prevention and control of Canine leishmaniasis. An evaluation of the Scalibor collar was undertaken in leishmaniasis active sites in Tunis area, (northern Tunisia). Eighty leishmaniasis free dogs (42 collared and 38 as control dogs) were submitted to a serological detection using ELISA technique for anti-Leishmania antibodies before and after transmission season in 2005 and 2006. Seroconversions were detected by ELISA and controlled by indirect immunofluorescence antibodies test. Confirmation of infection in seroconverted dogs was based on the detection of the parasite by culture in NNN medium or detection of parasite's DNA by real time PCR. Among 38 control dogs, 6 (15.8%) were infected by Leishmania infantum during the study period against zero in the collar group; the difference is statistically significant (p=0.02). This result is an additional confirmation of the prophylactic properties of Scalibor protector band against canine leishmaniosis.

A survival of A. hydrophila B3 has been conducted in different conditions (mineral water, seawater exposed or not to the sunlight). Also, unculturable forms have been detected by using epifluorescence microscopy. Thus, different kinds of microcosms were prepared using filtered and autoclaved marine water or mineral water, inoculated by A. hydrophila B3 and maintained or not in room light. Further, we tested the survival of A. hydrophila B3 incubated in seawater and exposed to sunlight. Our results revealed that the culturable count of A. hydrophila B3 incubated in different conditions declined. Nevertheless, no variations were obtained for the total bacterial cells. Morphological, biochemical and antimicrobial modifications were noted.

Snake venoms are a rich natural source of bioactive molecules, such as peptides, proteins and enzymes, more and more used in biomedical research in diagnostic or therapeutic purposes. The protein components of snake venoms belong to diverse families such as serine proteases, phospholipases, disintegrins, metalloproteinases and C-type lectins. Due to their effects on various receptors such as GPIb, GPVI, alpha2beta1..., the C-type lectins were considered, in first time, as modulators of the platelet aggregation. Recently, some of them have been described for their anti-tumoral potential effect due to their capacity to inhibit adhesion, migration, proliferation and invasion of different cancer cell lines. Also, the C-type lectins have a powerful antiangiogenic effect in vivo and in vitro by interacting with integrins of endothelial cells.

Leishmaniasis are a group of vector-born, parasitic diseases caused by protozoan of the Leishmania genus, that includes visceral or cutaneous forms. Cutaneous leishmaniasis (CL) refers to a group of diseases because of the variability of clinical manifestations, caused by a large number of Leishmania species. In Tunisia, three different forms of CL are encountered, having different causal agents L. infantum, L. major and L. tropica. For the purpose of this study, we assessed the potential of polymorphic sites in dipeptidyl peptidase III (DPP III) encoding gene to differentiate among Leishmania species encountered in Tunisia. A pair of forward and reverse primers amplifying a 664 bp DPP III sequence were designed in regions including 2 mutations in the forward primer and 1 in the reverse, and were used to amplify DNA from diverse species of Leishmania parasites including L. infantum, L. major, L. tropica, L. donovani, L. chagasi, L. arabica, L. aethiopica and L. tarentolae. Amplification was positive for all tested Leishmania species except for L. infantum, L. chagasi, L. archibaldi, L. donovani and L. tarentolae. In case of cutaneous Leishmania species encountered in Tunisia, amplification was positive for both L. tropica and L. major and negative in case of L. infantum. This ability to differentiate L. infantum from L. tropica/L. major constitutes a first step in the taxonomy of cutaneous species prevalent in Tunisia.

A follow-up study of 917 dogs was undertaken between 1994 and 1995 in the focus of visceral leishmaniasis in northern Tunisia. It permitted to assess the demography of the dog population, the importance of canine leishmaniasis (CL) and the determinants of seropositivity and mortality of dogs. Canine population was stable through time with an input of 231 dogs and an output of 218 dogs per year. The prevalence of seropositivity was 18% and 22.3% in 1994 and 1995 respectively and 90% of dogs were asymptomatic. Among 525 negative dogs in 1994 and reassessed in 1995, 78 seroconverted revealing an annual cumulative incidence of 14.74%. On the other hand, 23.47% (27/115) of seropositive dogs became negative in 1995. Age, presence of symptoms and density of dogs were independently associated with CL seropositivity. These results demonstrate the difficulty of control strategies of visceral leishmaniasis targeting the dog population.

Nine different species of scorpions can be recognized from more than 5000 samples collected from different areas in Libya: Leiurus quinquestriatus, Androctonus bicolor, Androctonus australis, Androctonus amoreuxi, Buthacus leptochelys, Buthus occitanus, Buthacus arenicola, Orthochirus innesi and Scorpio maurus. The geographical occurrence showed that Leiurus quinquestriatus seems to be restricted to the Southern areas. On the contrary, Buthus occitanus was found in the costal regions. Other species such as Androctonus were widely spread in all regions. Buthacus Leptochelys, Orthochirus innesi and Scorpio maurus were found, in the East (Aujlah, Jalu), the South (Wadi-Atbah) and the Western cost of Libya respectively.

Staphylococcus aureus is a major hospital and community acquired pathogen. A total of one hundred strains were investigated. They were collected from January 2004 to July 2006 in the laboratory of microbiology at Charles Nicolle University hospital of Tunis. The isolates were identified by conventional methods. Methicillin resistance was confirmed by amplification of mecA gene by PCR. The agr groups were identified by multiplex PCR. The agr groups were distributed as follows: 19 strains belonged to group I, 16 to group II and 65 to group III. Among methicillin resistant S. aureus (MRSA), 9 (16.4%) belonged to group 1, 8 (14.5%) to group II and 38 (69.1%) to group IlI. For methicillin susceptible S. aureus (MSSA), only 10 strains (22.2%) belonged to group I, 8 (17.8%) to group II and 27 (60%) to group III. A preferential link was observed between agr group I and invasive infections (P=0.003) especially bacteremia (P=10(-4). Besides, agr groups II and III were closely related with non invasive infections (P=0.003). No association was found between other types of infections and agr groups. Likewise, no correlation was observed between agr groups, age or sex of patients and type of infections.

Due to its heterogeneity and pathogenesis diversity, antiphospholipid syndrom remains a challenge for researchers more than a century after first antibody, the anticardiolipin antibody for syphilis diagnosis was discovered. After a review of the etiology and epitopic specificities of antiphospholipid antibodies, we propose a detailed overview of mechanisms and clinical aspects of antiphospholipid syndrome. We emphasize on the role of innate immunity and the involvement of endothelial cells Toll like receptors in the transduction signal of anti-beta2-glycoprotein I antibodies fixation, which induce a thrombogenic state. The thrombogenic role of the anti-beta2GPI antibodies direct against beta2GPI domain I in the clinical onset of this syndrome is also evoked. Diagnosis problems and clinicobiological manifestations in the light of the last international consensus statement of the classification criteria for antiphospholipid syndrome end this review.

Detection of enterovirus genome by PCR in clinical samples is now extensively used for the diagnostic of enterovirus infections given its rapidity and high sensitivity. In contrast, its use in surveillance programs targeting specific enterovirus serotypes remains less frequent. The most sensitive protocols are those amplifying in the 5'untranslated region (5'UTR). However the possibility to use sequence analysis of the 5'UTR amplicons for serotype identification is not yet well established. In this report, stool samples from polio suspected cases and their healthy contacts were tested. The results of direct detection of enterovirus genome by PCR and serotype identification based on sequence analysis of the PCR products in the 5'UTR were compared to those of standard cell-culture-based protocols. Standard protocols detected enterovirus isolates in 7.4% of cases while 9.8% of samples were positive by PCR. Serotype identification based on sequence analysis of amplicons showed concordant results with serotypes determined on virus isolates by seroneutralisation or sequencing in the VP1 gene in 39% of cases only. These results confirm that the use of PCR amplification from stool samples improves the sensitivity of enterovirus detection but do not recommend the use of sequence analysis of the 5'UTR PCR product to determine enterovirus serotype.

Acinetobacter baumannii (A. baumannii) is often implicated in hospital outbreaks in Tunisia. It's a significant opportunistic pathogen that is usually associated with serious underlying diseases such as pneumoniae, meningitis and urinary tract infections. The aim of this prospective study was to evaluate the global state of its endemicity and the antibiotic resistance evolution. The possibility of nosocomial transmission of one or more epidemic strain(s) was investigated by means of 3 methods: biotyping, antibiotyping and Random Amplified Polymorphic DNA analysis (RAPD). MIC for imipenem by Ellipsometer-test strip (E-TEST). The presence of metallo-beta-lactamases (MBL) was detected according to the double synergy test of EDTA and imipenem disks. A. baumannii strains were mainly localized in intensive care (52.2%) and surgery units (23.6%). Among 224 strains that were studied, 4 biotypes were delineated with a predominance of biotype1. Resistance to beta-lactams was mostly associated with the production of cephalosporinases and penicilinases (84.3%). 45% of strains were resistant to imipenem which were associated with MBL production. RAPD gave 5 genomic groups. This study demonstrates the epidemic behaviour airborne spread of A. baumannii in hospital wards. The multiresistance was often responsible for failure of antibiotics therapy. The prevention of nosocomial infection and severe hygiene controls must be performed.