Phenotypic and genotypic characterization of meningococcal isolates in Tunis, Tunisia: High diversity and impact on vaccination strategies.
Int J Infect Dis 2019;
91:73-78. [PMID:
31756567 DOI:
10.1016/j.ijid.2019.11.013]
[Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/07/2019] [Accepted: 11/12/2019] [Indexed: 12/15/2022] Open
Abstract
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.
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