In-utero coxsackievirus B4 infection of the mouse thymus.

Type B coxsackievirus (CV-B) infections are involved frequently in the triggering of several autoimmune diseases such as myocarditis, dilated cardiomyopathy, pericarditis, pancreatitis, type 1 diabetes, encephalitis, thyroiditis or Sjögren's syndrome. Serological and virological evidence suggests that maternal infections during pregnancy can play a role in the appearance of these diseases in offspring. The current study aims to explore the effect of an in-utero CV-B infection on the fetal thymus, the central site for programming immunological self-tolerance. In this perspective, female Swiss albino mice were inoculated intraperitoneally or orally with the diabetogenic CV-B4 E2 strain at gestational days 10 or 17. Offspring were killed at different post-inoculation times, and their thymuses were analysed for evidence of infection and alterations in thymic T cell subsets. In-utero CV-B infection of the thymus was demonstrated during the course of vertical transmission, as attested by viral RNA and infectious virus detection in most analysed samples. No histopathological changes were evident. Thymic T cells were not depleted, despite being positive for viral RNA. As evidenced by flow cytometry analysis, CV-B infection of the fetal thymus induced significant changes of thymic T cell populations, particularly with maternal inoculation at gestational day 10. Altogether, these findings suggest that CV-B infection of the fetal thymus may play an important role in the genesis of autoimmune diseases.

Impact and long-term protection of hepatitis B vaccination: 17 years after universal hepatitis B vaccination in Tunisia.

Hepatitis B virus (HBV) vaccination has been part of the Expanded Programme of Immunization (EPI) in Tunisia since 1995. The aim of this study was to evaluate, for the first time, the impact of mass vaccination in Tunisia 17 years after this programme was implemented, and in parallel, assess the long-term persistence of anti-HBs antibody in the vaccinated Tunisian population. A total of 1422 students were recruited (703 vaccinated, 719 non-vaccinated). HBV seromarkers were checked. None of the students from either group had positive HBsAg. The overall prevalence of anti-HBc was 0·8%. A Significantly higher prevalence of anti-HBc was noted in unvaccinated students than in vaccinated (1·4% vs. 0·3%, P = 0·02). The overall seroprotection rate (anti-HBs titre ⩾10 mIU/ml) was 68·9% in vaccinated subjects. Seroprotection rates and geometric mean titres decreased significantly with increasing age, reflecting waning anti-HBs titre over time. No significant difference was detected between seroprotection rates and gender or students' area of origin. Incomplete vaccination was the only factor associated with an anti-HBs titre <10 mIU/ml. This study demonstrates the excellent efficacy of the HBV vaccination programme in Tunisia 17 years after its launch. However, a significant decline of anti-HBs seroprotection has been observed in ⩾15-year-old adolescents which places them at risk of infection. Additional studies are needed in hyperendemic regions in Tunisia.

Antibacterial and antibiofilm activities of Laurus nobilis L. essential oil against Staphylococcus aureus strains associated with oral infections.

BACKGROUND: Laurus nobilis L. is an aromatic herb with relevant medicinal properties due to its important chemical composition and its potential therapeutic effects. In this study, we investigate the chemical composition, the antibacterial and the antibiofilms activities of Tunisian L. nobilis L. essential oils against clinical Staphylococcus aureus strains. METHODS: The chemical composition of L. nobilis L. essential oils was analysed by Gas Chromatography-Mass Spectrometry (GC-MS). The antibacterial activity of L. nobilis L. essential oils was evaluated in vitro against oral S. aureus (n=21) strains using broth microdilution method. The antibiofilm activity was assessed via Crystal Violet staining and MTT assays. RESULTS: Our results revealed that GC-MS assay exhibited 1.8-Cineole, methyl eugenol and α-terpinyl acetate as the major compounds in the essential oils. Moreover, the essential oil from Sousse exhibited the best bactericidal activity (MICs values ranged from 3.91 to 15.62mgm-1). Furthermore, this oil showed a strong biofilm inhibition effect above 70%, from a low sub-inhibitory concentration (1/16×MIC). MTT assay revealed that both essential oils displayed an excellent antibiofilm activity with eradication percentages ranging from 79.6±2.27 to 95.2±0.56. CONCLUSION: Our finding demonstrated that L. nobilis L. essential oils are able to inhibit oral S. aureus strains with important antibiofilm efficacy. It could have a promising role in the prevention of oral diseases.

Detection and genotyping of group A rotaviruses isolated from sewage samples in Monastir, Tunisia between April 2007 and April 2010.

AIMS: To ascertain the viral load, the distribution of G and P types of group A rotaviruses (RV-A) in sewage samples and to compare strains in clinical, animal and environmental samples. METHODS AND RESULTS: During our study from April 2007 to April 2010, 518 samples of raw and treated sewage were collected from two biological sewage treatment plants (STPs) located in the Monastir region, Tunisia. RV-A was detected by real-time RT-PCR in 375 (72·4%) sewage samples. According to the quantification results of RV-A, it appears that the viral load in raw and treated sewage of the two STPs was quite similar (P = 0·735). The genotyping of RV-A strains detected in sewage samples showed a great diversity with 10 G types and 8 P types. Most of them were described as common in humans, but we also detected genotypes commonly found in animals. All the genotypes detected in two previous studies performed in our laboratory on clinical and bovine samples were also found in environmental samples. However, some genotypes commonly found in animal were only found in sewage samples. CONCLUSION: The comparison of environmental, clinical and animal data suggests that STPs may convey not only human sewage but also animal wastes, both of them contaminated with numerous RV-A strains which are not efficiently eliminated by the sewage treatment process and may spread to surface waters. SIGNIFICANCE AND IMPACT OF THE STUDY: This work demonstrates the potential release of human and animal RV-A into water sources, representing a public health risk, by inducing gastroenteritis in population, but also by increasing the risk of zoonotic transmission and formation of reassortant viruses which could get a higher infectious potential. Our findings also suggest that monitoring of sewage may provide an additional tool to determine the epidemiology of RV-A circulating in a given community.

Relationship between GII.3 norovirus infections and blood group antigens in young children in Tunisia.

Noroviruses (NoVs) constitute a major cause of gastroenteritis in Tunisia. One hundred and fourteen matched saliva and stool samples were collected from children (n = 114) suffering from acute gastroenteritis at the hospital of Monastir during the winter season 2011-2012. For 98 of 114 children, blood samples were collected for secretor genotyping. NoVs were associated with 36.8% (n = 42/114) of the gastroenteritis cases. The GII.3 genotype was the most common (69% of all NoVs). For patients who were phenotyped (n = 114) for human blood group antigens (HBGAs), the secretor and non-secretor phenotypes represented 79% and 21%, respectively. Of the NoV infections, 83% were detected in all ABO groups. Five GII.3 isolates, one GII.1 isolate and one GII.7 isolate were detected in Lewis-positive non-secretors, confirmed by genotyping of the FUT2 gene. Even though our data showed that GII.3 NoVs could infect non-secretors, no binding was observed with saliva and GII.3 baculovirus-expressed virus-like particles from the same symptomatic non-secretor individual. This suggests that other factors might also participate in NoV attachment in children and newborns.

Age- and gender-specific effects on VDR gene polymorphisms and risk of the development of multiple sclerosis in Tunisians: a preliminary study.

The vitamin D receptor (VDR) polymorphisms have been reported to be associated with multiple sclerosis (MS); however, evidence remains conflicting. In this report, we investigated the association between two single nucleotide polymorphisms (SNPs) TaqI and ApaI of VDR gene and risk development of MS. TaqI and ApaI SNPs were detected by PCR-RFLP from the DNA of 60 Tunisian patients with MS and 114 healthy controls. Our results show a significant difference of the allelic frequency distribution between the case and control groups for TaqI SNP (P = 0.01), but genotype frequencies were not significantly different (P = 0.07 and 0.23). When adjusting frequency distribution of different alleles and genotypes by age, we found that the difference between the T allele frequencies of this SNP in the group of patients age [15-24] in comparison with the control group of the same age group was statistically significant (P = 0.026). Moreover, frequency of the T allele was significantly higher in male patients compared with controls of the same sex (P = 0.017). However, neither the genotype nor the allele frequency distribution was significantly different between the MS and control populations for the ApaI SNP. Our preliminary results indicate that VDR gene polymorphism could be associated with susceptibility to MS. The role of VDR gene polymorphism should be further studied in other large populations, and the distribution of other polymorphism, such as FokI and BsmI, should be also analysed to confirm another susceptibility polymorphisms gene for MS and to obtain more adequate strategies for treatment of MS.

Hepatitis E virus genotypes 1 and 3 in wastewater samples in Tunisia.

Hepatitis E represents an important public-health concern throughout the world. It is one of the leading causes of hepatitis in North Africa, Asia and the Middle East. In Tunisia, the true burden of HEV infection is still unknown. The objectives of the present study were to assess the occurrence of hepatitis E virus in Tunisia through the monitoring of urban sewage and to characterize the strains identified using molecular assays. A total of 150 sewage samples (raw and treated) were collected from three wastewater treatment plants located in the regions of Monastir and Mahdia and analyzed by nested RT-PCR using a qualitative assay targeting the methyltransferase gene in ORF1. Of these, only three samples (2 %) were found to be positive for HEV, one belonging to genotype 1 and two to genotype 3. The results of the present study indicate a low level of virus excretion among the Tunisian population. Both genotypes 1 and 3 are circulating in this country, however, possibly causing sporadic infections. The presence of the zoonotic genotype 3, known to be transmitted to humans mainly by swine and demonstrated in Tunisia for the first time in this work, raises the question of possible reservoir species, since pork products are not consumed in this country, pigs are not bred, and wild boar is not endemic. Further studies will be needed to gather information on the occurrence and diversity of HEV strains circulating among humans and animals in Tunisia, and on possible animal reservoirs.

Kikuchi-Fujimoto disease: report of 4 cases and review of the literature.

INTRODUCTION: Kikuchi-Fujimoto disease or histiocytic necrotizing lymphadenitis is a benign disease of unknown origin predominantly affecting young women and presenting in the form of cervical lymphadenopathy and/or prolonged fever. MATERIAL AND METHODS: The authors report 4 cases of Kikuchi-Fujimoto disease diagnosed in the Internal Medicine Department of Ibn Sina university hospital in Rabat between 2009 and 2010. RESULTS: These 4 women with a mean age of 27±8.6years [16-37] were admitted with febrile syndrome and cervical lymphadenopathy. The diagnosis was based on histological examination of a lymph node biopsy. The disease was associated with systemic lupus erythematosus in one case and actinomycosis in another case. A favourable course was observed in response to corticosteroid therapy in two patients, antibiotic therapy in one patient and antipyretic treatment alone in the fourth patient. CONCLUSION: In the light of these four cases, the authors discuss the diagnostic difficulties, the modalities of treatment of Kikuchi-Fujimoto disease and its clinical course.

Qualitative and Quantitative Assessment of Hepatitis A Virus in Wastewaters in Tunisia.

Hepatitis A causes substantial morbidity in both industrialized and non-industrialized countries and represents an important health problem in several southern Mediterranean countries. The objectives of the study were as follows: (a) to assess the occurrence of hepatitis A virus (HAV) in Tunisia through the monitoring of urban wastewaters collected at wastewater treatment plants (WTPs); (b) to characterize environmental strains; and (c) to estimate the viral load in raw and treated sewages, in order to evaluate the potential impact on superficial waters receiving discharges. A total of 150 raw and treated wastewaters were collected from three WTPs and analyzed by both qualitative (RT-PCR/nested) and quantitative (qRT-PCR) methods. Of these, 100 (66%) were found to be positive for HAV by the qualitative assay: 68.3% in influents and 64.7% in effluents. The vast majority of HAV sequences belonged to sub-genotype IA, with 11 different strains detected found to be identical to clinical strains isolated from Tunisian patients with acute hepatitis. Five unique variants were also detected, not previously reported in clinical cases. Only two IB strains were found, confirming the rarity of this sub-genotype in this country. The results of the present study indicate a wide circulation of the pathogen in the population, most probably in the form of asymptomatic infections, a finding consistent with the classification of the country as having intermediate/high endemicity. Quantitative data showed high viral loads in influents (3.5E+05 genome copies/liter, mean value) as well as effluents (2.5E+05 genome copies/liter, mean value), suggesting that contaminated water could be a critical element in transmission.

Distribution of G (VP7) and P (VP4) genotypes of group A bovine rotaviruses from Tunisian calves with diarrhoea.

AIMS: To investigate the incidence, viral load and genetic diversity of bovine rotaviruses strains in Tunisia. METHODS AND RESULTS: A total of 169 faecal specimens, collected from diarrhoeic calves from several farms located in the central eastern regions of Tunisia, between January 2006 and October 2010, were analysed by semi-nested multiplex RT-PCRs for P and G genotypes identification or were genotyped by DNA sequencing. Positive samples were tested by TaqMan real-time RT-PCR to quantify the viral load. Group A bovine rotaviruses were detected in 15·4% (26/169) of the total studied cases of diarrhoea. Overall, G10 was the predominant G type, detected in 12/26 samples (46·2%) and G6 accounted for 42·3% (11/26) while P[11] was the predominant P type, detected in 12/26 samples (46·2%). Two P[5] genotypes (7·7%) were found in the collection. Dual G or P combination and genotype G8 were not found. The most common VP7/VP4 combinations were G6P[11] (30·8%; n = 8) and G10P[11] (11·5%; n = 3). The combination G10P[14] was seen in one sample, and partial typing was assessed in 53·8% (n = 14) of the cases. The viral load determined by real-time RT-PCR showed an average of 1·68 × 10(9) genome copies/g of faeces. CONCLUSION: Knowledge of P and G types could help us understand the relatedness of animal rotaviruses to viruses causing disease in humans. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first time that the viral load and P types of bovine rotaviruses have been determined in Tunisia, and this study contributes to a better understanding of the epidemiology of such viruses circulating in Tunisia. Nevertheless, continuous surveillance is necessary to detect the emergence of new variants.

Real-time PCR using SYBR Green for the detection of Shigella spp. in food and stool samples.

Shigella spp are exquisitely fastidious Gram negative organisms that frequently get missed in the detection by traditional culture methods. For this reason, this work has adapted a classical PCR for detection of Shigella in food and stool specimens to real-time PCR using the SYBR Green format. This method follows a melting curve analysis to be more rapid and provide both qualitative and quantitative data about the targeted pathogen. A total of 117 stool samples with diarrhea and 102 food samples were analyzed in Public Health Regional Laboratory of Nabeul by traditional culture methods and real-time PCR. To validate the real-time PCR assay, an experiment was conducted with both spiked and naturally contaminated stool samples. All Shigella strains tested were ipaH positive and all non-Shigella strains yielded no amplification products. The melting temperature (T(m) = 81.5 ± 0.5 °C) was consistently specific for the amplicon. Correlation coefficients of standard curves constructed using the quantification cycle (C(q)) versus copy numbers of Shigella showed good linearity (R² = 0.995; slope = 2.952) and the minimum level of detection was 1.5 × 10³ CFU/g feces. All food samples analyzed were negative for Shigella by standard culture methods, whereas ipaH was detected in 8.8% culture negative food products. Moreover, the ipaH specific PCR system increased the detection rate over that by culture alone from 1.7% to 11.1% among patients with diarrhea. The data presented here shows that the SYBR Green I was suitable for use in the real-time PCR assay, which provided a specific, sensitive and efficient method for the detection and quantification of Shigella spp in food and stool samples.

Detection and characterization of Shigella species isolated from food and human stool samples in Nabeul, Tunisia, by molecular methods and culture techniques.

AIMS: This study was designed to isolate Shigella spp. strains from food and stool samples by a combination of PCR and culture methods and characterize their serotypes, antibiotic resistance profiles, virulence genes and pulsed-field gel electrophoresis (PFGE) patterns to investigate possible clonal relationships amongst strains circulating. METHODS AND RESULTS: Six Shigella spp. strains were isolated from 280 food samples against 16 Shigella isolates from 236 stool samples of symptomatic patients and asymptomatic food handlers during the period from January 2007 to December 2009 in Public Health Regional Laboratory of Nabeul. The detection of ipaH, ipaBCD, ial, ShET-1 and ShET-2 was performed by a PCR technique with specific primers. CONCLUSIONS: The use of PCR technique improved the rate of detecting Shigella in stool samples from 6·7 to 14% and in food samples from 2·1 to 8·6%. Percentage of Shigella isolates and ipaH-specific PCR demonstrated a marked pattern of seasonality, increasing in summer and fall seasons for human and food isolates. Amongst the environmental strains, 50% of isolates were invasive. However, for the 16 clinical strains isolated, nine were found to be positive for both ial and ipaBCD gene and 11 were found to produce ShET-1 and/or ShET-2. XbaI PFGE analysis revealed the presence of a predominant clone amongst Shigella sonnei strains recovered from different sources circulating in Nabeul, Tunisia, throughout the years 2007-2009. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated the existence of Shigella in food samples and dispersion of different virulence genes amongst these isolates, which appear to constitute an environmental source of epidemic spread. The clonal relationships amongst strains isolated from food elements and human stools indicate the incrimination of different kinds of foods as vehicle of transmission of Shigella, which are usually escaped from detection by traditional culture methods.

Persistent infection of human intestinal Caco-2 cell line by Coxsackieviruses B.

Coxsackieviruses B (CV-B, Picornaviridae family, genus Enterovirus) are characterized by their ability to cause cytopathic effects in tissue culture. These viruses are considered highly cytolytic, but can establish persistence/latency in susceptible cells, indicating that a regulatory mechanism may exist to shut off viral protein synthesis and replication under certain situations. The persistence of coxsackieviral B RNA is of great interest because of its implication in the pathogenesis of several chronic human diseases. However, a few studies have dealt with the persistence of these viruses at the intestinal level. The aim of this study is to test the capacity of the six CV-B serotypes to establish persistent infection in human intestinal Caco-2 cell line. Ten CV-B isolates, including CV-B3 prototype strain (Nancy) and a recombinant isolate (B3-B4), were tested. Six CV-B isolates were found to establish persistent infections in Caco-2 cell line. Persistent replication was proved by the detection of viral RNA from cell cultures, VP1 capsid protein detection by immunofluorescence (IF) staining, and the release of infectious particles up to two months and a half after infection without any obvious cytolysis. In addition, our results suggest that the establishment of a persistent infection is serotype-independent.

[Seroprevalence and risk factors of human herpes virus 8 infection in Central-East Tunisia]. / Séroprévalence et facteurs de risque de l'infection par le virus herpès humain 8 dans le Centre-Est tunisien.

OBJECTIVE: Epidemiology of human herpesvirus 8 (HHV8) is still unknown in Tunisia. We aimed to assess the prevalence of HHV8 infection in adults and children from Central-East Tunisia and in patients with high risk of parenteral or sexual infection. METHODS: We enrolled 553 subjects: 116 blood donors, 100 pregnant women, 100 children, 50 subjects with sexually transmitted infections with positive HIV serology and 50 other without HIV infection, 107 multitransfused patients and 30 kidney transplant patients. Antibodies against HHV8 were tested using a sensitive indirect immunofluorescence assay. RESULTS: The seroprevalence of HHV8 was found to be 13.8% in blood donors, 13% in pregnant women and 12% in children. In healthy adult population, no association was found between HHV8 seropositivity and sex, sociodemographic characteristics, parenteral risk factors or serological markers of hepatitis B. Rates of HHV8 infection were significantly higher in patients having high-risk sexual behavior with or without HIV infection (P<10(-4)), in polytransfused patients (P<10(-4)) and in patients with kidney transplantation (P=0.001). CONCLUSION: Our findings suggest that HHV8 infection is widespread in Central-East Tunisia such as in the Mediterranean area. HHV8 infection appears to be acquired early in life, probably through saliva. HHV8 transmission by blood transfusion, subject of controversy in literature, is well established in our study. Early screening of this infection should be considered in populations with high risk of Kaposi's sarcoma in our areas.

In vitro antiviral activities of extracts derived from Daucus maritimus seeds.

The antiviral activities of extracts from Daucus maritimus seeds were investigated against the reverse transcriptase of human immunodeficiency virus (HIV) type 1 and a panel of RNA-dependent RNA polymerases of dengue virus, West Nile virus (WNV) and hepatitis C virus (HCV). The extracts showed moderate to potent inhibition rates against the four viral polymerases. The ethyl acetate extract exhibited a potent inhibitory effect against WNV's RdRp, with an IC50 value of 8 µg mL⁻¹. The F2 fraction exhibited potent inhibitory activity against WNV and HCV's RdRps, with IC50 values 1 and 5 µg mL⁻¹, respectively. The P2 fraction also showed potent inhibitory effects on WNV and HCV's RdRps, with IC50 values 2.7 and 4 µg mL⁻¹, respectively. The results suggest that these extracts are candidates for the development of new anti-WNV RpDp and anti-HCV RpDp agents.

[Kikuchi-Fujimoto's disease: Report of 4 cases and literature review]. / Maladie de Kikuchi-Fujimoto : à propos de quatre cas et revue de littérature.

INTRODUCTION: Kikuchi-Fujimoto's disease or histiocytic necrotizing lymphadenitis is a benign disease predominantly occurring in young women which etiology remains unknown and revealed by cervical lymphadenitis and/or prolonged fever. OBSERVATIONS: This report describes a survey of four patients who developed Kikuchi's lymphadenitis occurring concomitantly with LES in one case and actinomycosis in another case. The definite diagnosis is usually made through histopathological examination of a lymph node biopsy. The evolution was favorable under corticosteroid therapy in two patients, antibiotics in the third and only antipyretic in the fourth. CONCLUSION: The authors bring report through these three observations, the diagnostic difficulties, the therapeutic means of the disease of Kikuchi, as well as its evolutionary aspects.

Anti-inflammatory and analgesic activities of Tunisian Citrullus colocynthis Schrad. immature fruit and seed organic extracts.

BACKGROUND AND OBJECTIVES: Inflammations and immune-related diseases including rheumatoid arthritis are widespread in the entire globe. The treatment of these illnesses is mainly based on the use of synthetic and biotechnological drugs, in recent years. Tunisian traditional medicine is a potential source of new remedies namely Citrullus colocynthis Schrad. (Cucurbitaceae): endemic in southern Tunisia and used in folk medicine to treat many inflammation disorders. Our goal was to assess the in vivo analgesic and anti-inflammatory activities of Tunisian Citrullus colocynthis immature fruit and seed organic extracts (petroleum ether, chloroform, ethyl acetate, acetone and finely methanol extract). MATERIAL AND METHODS: Yields of prepared organic extracts are gravimetrically determined. For the analgesic and anti-inflammatory activities, we have used respectively, the acetic acid writhing test in mice and the carrageenan-induced paw edema assay in rats. RESULTS AND DISCUSSION: All extracts displayed an important analgesic and anti-inflammatory activities at different doses without inducing any side effects. This study has demonstrated the analgesic and anti-inflammatory activities of Citrullus colocynthis immature fruit and seed extracts. Experiment results provide scientific insight into the ancient practice of utilizing Citrullus colocynthis Schrad. as analgesic and as anti-inflammatory agents.

[Ocular complications of HIV infection: experience of the Northern Excellence Pole of Morocco]. / Les complications oculaires au cours de l'infection par le VIH : expérience du pôle d'excellence Nord du Maroc.

INTRODUCTION: HIV infection is associated with a wide variety of ophthalmic manifestations. The objective of this study was to identify the ocular complications of HIV/AIDS in Morocco. MATERIAL AND METHODS: A retrospective study conducted in the internal medicine department of the Rabat Teaching Hospital between 1998 and 2008. All HIV-positive patients were retained for the study. Each patient had an exhaustive ocular examination. RESULTS: Of 115 ophthalmologic examinations, 28 were abnormal. Twenty-seven patients had stage C HIV infection and one patient was in stage A. The ocular manifestations were: 21 cases of ocular HIV-related anomalies (microangiopathies), four cases of cytomegalovirus (CMV) retinitis, one case of toxoplasmosis chorioretinitis, one case of CMV retinitis associated with toxoplasmosis chorioretinitis, two cases of Cryptococcus neoformans infection, two cases of varicella-zoster virus (VZV) retinitis, and one case of conjunctival Kaposi sarcoma. The CD4 count average was of 86±91/mm(3). Twenty-six patients had a CD4 count lower than 200/mm(3). Progression was favorable in 85 % of the cases, with three cases of blindness: bilateral in a case of VZV retinitis and unilateral in two cases of CMV retinitis and toxoplasmosis chorioretinitis. CONCLUSION: CMV infection is the main ocular opportunistic infection in our series. However, Highly Active Antiretroviral Treatment (HAART) may be the cause for the decline in the prevalence of ocular diseases and visual impairment in HIV/AIDS.

Impedance biosensing using phages for bacteria detection: generation of dual signals as the clue for in-chip assay confirmation.

In the present work, we compare the use of antibodies (Ab) and phages as bioreceptors for bacteria biosensing by Electrochemical Impedance Spectroscopy (EIS). With this aim, both biocomponents have been immobilised in parallel onto interdigitated gold microelectrodes. The produced surfaces have been characterised by EIS and Fourier Transform Infra-Red (FTIR) Spectroscopy and have been applied to bacteria detection. Compared to immunocapture, detection using phages generates successive dual signals of opposite trend over time, which consist of an initial increase in impedance caused by bacteria capture followed by impedance decrease attributed to phage-induced lysis. Such dual signals can be easily distinguished from those caused by non-specific adsorption and/or crossbinding, which helps to circumvent one of the main drawbacks of reagentless biosensors based in a single target-binding event. The described strategy has generated specific detection of Escherichia coli in the range of 10(4)-10(7) CFU mL(-1) and minimal interference by non-target Lactobacillus. We propose that the utilisation of phages as capture biocomponent for bacteria capture and EIS detection allows in-chip signal confirmation.