Effect of Previous Incubation of Aeromonas hydrophila in Wastewater Prior to Its Transfer Into Marine Water Microcosms

The occurrence of the mesophilic motile Gram negative non enterobacterial species A. hydrophila in the wild is a major problem that deserves to be resolved since it is a potentially pathogen able to enter into a non-culturable state on routine bacteriological plating media. These non-culturable forms can be detected by several direct or indirect visualization methods. This species has frequently been isolated from pathological forms in fish farming marine areas, especially near wastewater discharges. Consequently, we studied A. hydrophila in marine water microcosms placed during a 24 hour period in treated waste waters and compared with the homologous strain not placed in the same conditions. Thus, two kinds of microcosms were prepared using filtered and autoclaved marine water or waste water, inoculated by A. hydrophila and maintained at 25°C in darkness. The results obtained indicated that A. hydrophila population incubated at 25°C in marine water declined rapidly (3.21 log units in plate count number) during the first three days. Additionally, we noted that A. hydrophila incubated in marine water after a previous treatment in waste water declined progressively to 2.74 log units (in plate count number). Nevertheless, we showed no significant variations of the number of total bacterial cells for A. hydrophila developed in marine water after prior treatment in waste water, despite the appearance of the VBNC form. During this state, rods of normal size, elongated cells and cocci were obtained. Concomitantly, we determined several changes in biochemical and antimicrobial patterns of stressed A. hydrophila, notably the acquisition of adipate metabolization and an increase of resistance to antimicrobial compounds, especially for A. hydrophila incubated in marine water after treatment in waste water.A. hydrophila (mésophile, Gram négative, mobile) compte parmi les espèces non entérobactériennes opportunistes du milieu aquatique. Son isolement ou son dénombrement en milieu marin selon les méthodes classiques est compromis par l’acquisition de la forme viable non cultivable (VNC) chez la bactérie dont la visualisation repose sur des méthodes moins usuelles, notamment la cytométrie en image ou en flux. En pathologie aquacole, A. hydrophila compte parmi les espèces les plus fréquemment isolées, notamment dans les zones de rejets. Le présent travail a été effectué en vue d’étudier la survie d’A. hydrophila en eau de mer après transit en eaux usées domestique. Ainsi, deux types de microcosmes ont été utilisés, le premier rempli d’eau de mer filtrée, stérile et placé à 25 °C à l’obscurité; le second est rempli d’eau usée filtrée, stérile et placée pendant 24 h à l’obscurité avant transfert en eau de mer. Les caractéristiques intrinséques : cultivabilité, forme cellulaire, profils biochimiques et antibiotypiques ont été suivis au cours de ce stress. Les résultats obtenus indiquent que la cultivabilité d’A. hydrophila placée directement dans l’eau de mer diminue rapidement durant les trois premiers jours d’incubation (3,21 Ulog). Aussi, nous avons noté une réduction progressive de la cultivabilité d’A. hydrophila placée en eau de mer après transit en eaux usées (2,74 Ulog). Néanmoins, le nombre de cellules totales ne montre pas de variation significative tout le long de la période de suivi (30 jours), avec l’apparition de la forme Viable Non Cultivable (VNC). Au cours de ce stress, nous avons observé des cellules de formes bacillaires, allongées et arrondies réduites. Parallèlement, nous avons trouvé qu’A. hydrophila ayant séjourné en eau de mer (avec ou sans passage en eaux usées) a subi différentes modifications ayant porté aux caractéristiques biochimiques et antibiotypiques, dont les plus remarquables sont la capacité à métaboliser l’adipate et l’acquisition de nouvelles résistances aux antibiotiques, notamment après passage en eaux usées

External quality assessment of Rift Valley fever diagnosis in 17 veterinary laboratories of the Mediterranean and Black Sea regions

Rift Valley fever (RVF) is an arboviral zoonosis that primarily affects ruminants but can also cause illness in humans. The increasing impact of RVF in Africa and Middle East and the risk of expansion to other areas such as Europe, where competent mosquitos are already established, require the implementation of efficient surveillance programs in animal populations. For that, it is pivotal to regularly assess the performance of existing diagnostic tests and to evaluate the capacity of veterinary labs of endemic and non-endemic countries to detect the infection in an accurate and timely manner. In this context, the animal virology network of the MediLabSecure project organized between October 2016 and March 2017 an external quality assessment (EQA) to evaluate the RVF diagnostic capacities of beneficiary veterinary labs. This EQA was conceived as the last step of a training curriculum that included 2 diagnostic workshops that were organized by INIA-CISA (Spain) in 2015 and 2016. Seventeen veterinary diagnostic labs from 17 countries in the Mediterranean and Black Sea regions participated in this EQA. The exercise consisted of two panels of samples for molecular and serological detection of the virus. The laboratories were also provided with positive controls and all the kits and reagents necessary to perform the recommended diagnostic techniques. All the labs were able to apply the different protocols and to provide the results on time. The performance was good in the molecular panel with 70.6% of participants reporting 100% correct results, and excellent in the serological panel with 100% correct results reported by 94.1% of the labs. This EQA provided a good overview of the RVFV diagnostic capacities of the involved labs and demonstrated that most of them were able to correctly identify the virus genome and antibodies in different animal samples

Phylogenetic analysis of hepatitis C virus isolates from Tunisian patients.

International audienceThere is little information on the epidemiology characterisation of HCV isolates in Tunisia. Previous report showed predominance of genotype 1b. In this study, 32 HCV isolates from genotypes 1a (n = 10), 1b (n = 14), 2 (n = 4), 3a (n = 3) and 4 (n = 1) were genotyped by sequencing and phylogenetic analysis on the non-structural 5b (NS5b) region. The isolates originated from 14 patients with chronic hepatitis, 10 haemophiliacs and eight healthy blood donors. NS5b sequence grouping was concordant with previous 5' untranslated region (5'UTR) genotyping results in 91% of cases. Most of the Tunisian isolates were closely related to the European ones, except for genotype 4 which seems to be related mostly to isolates from Egypt. Isolates from genotype 1a obtained from haemophiliacs showed distinct clustering and nucleic divergence from those obtained from non-haemophiliac patients, this underlines the particular mode of contamination of this group of patients

Serological evidence of Rift Valley fever in domestic ruminants in Tunisia underlines the need for effective surveillance

Background: Rift Valley fever (RVF) is an infectious zoonotic disease infecting, mainly, domestic ruminants and causing significant economic and public health problems. RVF is a vector-borne disease transmitted by mosquitoes.Aim: In this work, we tried to seek any RVF virus circulation in Tunisia.Methods: Thus, we investigated 1,723 sera from different parts of Tunisia, collected in 2009 and 2013–2015 from sheep, goats, cattle, and dromedaries. All sera were assessed using enzyme-linked immunosorbent assay techniques.Results: Eighty-seven sera were detected positive and 11 doubtful. All of them were investigated by the virusneutralization technique (VNT), which confirmed the positivity of three sera.Conclusion: This is the first case of RVF seropositive confirmed by the VNT in Tunisian ruminants. Such a result was expected considering the climate, entomology, and geographic location of the country. Further investigations must enhance our findings to understand the RVF epidemiologic situation better and implement risk-based surveillance programs and effective control strategies

Epizootic haemorrhagic disease virus circulation in Tunisia

Epizootic haemorrhagic disease virus (EHDV) was detected for the first time in Tunisia and in other Northern African countries in 2006.The objective of the present study was to investigate whether EHDV circulated in Tunisian livestock beforeand after the officially-reported outbreak of 2006.Thus, serum samples from cattle and dromedaries collected in different time periods (before and after 2006) and from different regions of Tunisia were screened for the presence of EHDV antibodies. Serological investigations conducted on cattle and dromedary sera collected in 2000 and 2001 demonstrated no virus circulation on these dates. However, viral circulation was evidenced in 2012 and 2013, although no EHDV cases were officially reported in these years. Serum-neutralization assessed on few ELISA positive samples, confirmed the presence of antibodies against EHDV serotype 6, which was the serotype involved in the EHDV outbreak in the Maghreb region in 2006