Phenotypic and genotypic characterization of meningococcal isolates in Tunis, Tunisia: High diversity and impact on vaccination strategies.

A. Brik (1, 2) , Aude Terrade (2) , Eva Hong (2) , Ala-Eddine Deghmane (2) , Muhamed-Kheir Taha (2) , A. Bouafsoun (1) , M. Khmiri (3) , K. Boussetta (3) , S. Boukhir (3) , N. Ben Jaballah (4) , A. Kechrid (1) , H. Smaoui (1)

1 UTM - Université de Tunis El Manar
2 Infections Bactériennes Invasives
3 Children’s Hospital of Tunis
4 Béchir Hamza Children's Hospital

OBJECTIVES: The aim of this study was to characterize Neisseria meningitidis (Men) isolates in Tunisian paediatric patients with invasive meningococcal disease (IMD) in order to target therapeutic and preventive strategies. METHODS: Fifty-nine isolates of Men and four cerebrospinal fluid samples that were culture-negative but Men-positive by PCR (NC-MenPPCR) (2009-2016) were collected from IMD patients. Isolates were analysed for their antimicrobial susceptibility. Whole-genome sequencing (WGS) was used to characterize isolates and multilocus sequence typing for NC-MenPPCR. Coverage of Men serogroup B (MenB) was determined by Genetic Meningococcal Antigen Typing System (gMATS) and fHbp expression by ELISA. RESULTS: MenB was the predominant type (88.9%). The majority of isolates (81%) had reduced susceptibility to penicillin G with altered penA alleles. The clonal complex CC461 (27.1%) was the most frequent. Among the MenB vaccine targets neisserial heparin binding antigen (NHBA) and fHbp, the predominant variants were NHBA118 (30.8%) and fHbp peptide 47 (25%), respectively. The nadA gene was present in 17.3% of isolates. Using gMATS, 36.5% of MenB were predicted to be covered by the 4CMenB vaccine. ELISA showed that 92.4% of the MenB were expected to be killed by anti-fHbp antibodies. CONCLUSIONS: MenB was the leading serogroup in IMD, and more than 90% had a sufficient level of fHbp expression for vaccine coverage. The study results will be useful for the Tunisian vaccination programme.

Mots clés: Invasive meningococcal disease; Meningococcal vaccine; Neisseria meningitidis serogroup B; Tunisia; Whole-genome sequencing; fHbp expression

Domaines: Maladies infectieuses

A. Brik, Aude Terrade, Eva Hong, Ala-Eddine Deghmane, Muhamed-Kheir Taha, et al.. Phenotypic and genotypic characterization of meningococcal isolates in Tunis, Tunisia: High diversity and impact on vaccination strategies.. International Journal of Infectious Diseases, 2020, 91, pp.73-78. ⟨10.1016/j.ijid.2019.11.013⟩. ⟨pasteur-02489606⟩