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

Abstract

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.

Epidemiological profile of Neisseria meningitidis in Casablanca, Morocco: 2010–2019

“…Comparable results have been reported by several studies, in Algeria, more than 46 % of the cases affected the age group of less than 10 years old [12]. In addition, in Tunisia, IMDs mainly affect infants at 44.6 % [13]. In the USA, the incidence of the disease is higher in the age group between 1 and 4 years [14].…”

“…Serogroup W appears to have increased worldwide since 2013 [26]. In the Maghreb region, serogroup W represents in Tunisia a prevalence of 1.6 % [13] and 14 % in Algeria between 1992 and 2013 [19]. In France, 9 % of isolates are due to this serogroup [21].…”

“…During this period, only three cases (1.22%) of serogroup Y were confirmed in Casablanca. In Tunisia, the serogroup Y represents 4.7 % (n=59) [13]. During the period 2005-2016, in Mexico, serogroup Y represents 23.53 % [28].…”

“…In Tunisia, the evolution of MDSP passed from 55.7 % combined in 2013 [18] to 81 % in 2016 [13]. In Algeria, MDSP represents 10.4 % between 1992 and 2013 [19].…”

A Review of the Epidemiology of Invasive Meningococcal Disease and Vaccination Strategies in North Africa

“…30,33,37 Despite efforts in Algeria, data on current serogroup distribution remain limited, aside from studies on the outbreak-causing MenW clone. 20 A recent study conducted in Tunisia 39 From the limited available data, N. meningitidis appears to be one of the most common causes of bacterial meningitis across North Africa, identified as the second or third most frequent cause of bacterial meningitis cases in Tunisia, following S. pneumoniae and H. influenzae. 23,24 Studies from Egypt identified N. meningitidis as the most common pathogen causing meningitis and had the highest CFR compared with other pathogens.…”