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

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.

[Seroprevalence of human parvovirus B19 in children with fever and rash in the North of Tunisia]. / Prévalence de l'infection par le parvovirus B19 humain au cours des éruptions fébriles de l'enfant dans le Nord tunisien.

The aim of the study is to evaluate the prevalence of specific antibodies anti-human parvovirus B19 (PVB19) immunoglobulin M (IgM) and IgG in children with fever and rash. This study involved 257 children aged from 7 months to 15 years with febrile rash unrelated to measles and rubella (seronegative for IgM). The sera were examined by immunoenzymatic assay. Detection of antibodies of PVB19 was done by enzyme-linked immunosorbent assay (Elisa). In our study, prevalence of immunoglobulin G (IgG) and IgM were 44 and 11.3%, respectively. Clinically, children with positive IgM serology had submitted an erythema infectiosum (13/29 cases), myocarditis (1 case), encephalitis (1 case), severe sickle cell anemia (7 cases), and immunocompromised (7 cases). The incidence rate of viral infection was 11.3%; most of the cases of PVB19 infection occurred between the months of May and August. Incidence was higher in the 10-15 years age group (21%). The prevalence of IgG antibody varied and increased with age, it rises from 38.2% in preschool children (19 months-4 years) to 53.5% in those aged between 4.5 and 15 years, reaching 58% in the 10-15 years age group. The four risk factors of PVB19 infection are: (1) those aged between 4.5 and 9 years, which is the most affected age group (P = 0.0018); (2) female gender in children aged between 19 months and 4 years (P = 0.037); (3) transfusion and (4) immune deficiency (P = 0.022 and P = 0.001, respectively). The study of the prevalence of PVB19 infection shows that viral infection is acquired early in childhood, increases with age; viral transmission is favored by the community life. Because of the widespread vaccination program against measles and rubella, the systematic search of PVB19 in front of eruptive fevers becomes important.

[Toxoplasmosis mother-to-child screening: study of cases followed in the Pasteur Institute of Tunis (2007-2010)]. / Dépistage de la toxoplasmose materno-foetale : étude des cas suivis à l'Institut Pasteur de Tunis (2007-2010).

Toxoplasmosis when occurring during pregnancy can be transmitted to the fetus and lead to congenital toxoplasmosis (CT). Therefore, pregnant women are a risk group, for which it is necessary to determine the serologic profile. The objective of this study is to determine the serologic profile of toxoplasmosis in pregnant women followed at the Parasitology Laboratory of the Pasteur Institute in Tunis, to establish the prevalence of toxoplasmic infections during pregnancy and the incidence of the CT, noting the difficulties faced in the interpretation of serological results. This is a retrospective study concerning 2833 toxoplasmic serologies practiced on 2070 pregnant women, followed at the Parasitology-Mycology Laboratory of the Pasteur Institute of Tunis, between 2007 and 2010. Serological diagnosis of toxoplasmosis was done by ELISA (Enzyme Linked Immunosorbent Assay) for the detection of Immunoglobulin (Ig) G and M and the study of toxoplasmosis IgG avidity. Prenatal diagnosis was performed for 58 women by amniotic fluid sampling. Toxoplasma gondii was detected by Polymerase Chain Reaction (PCR). At birth, the diagnosis of congenital toxoplasmosis was established based on serology. The toxoplasmic serologies carried out have shown that 45.6% of the pregnant women were formerly immunized while 49.6% had a negative serology. A toxoplasmosis primary infection acquired during pregnancy was detected in 79 cases (3.8%). Among them, 33% had a true seroconversion while 67% had a recent toxoplasmosis infection in view of the positivity of IgG and IgM on the first sample with a low index of avidity (IA). For 21 parturients whose serology showed the presence of IgG, IgM and an intermediate or high IA. Among the 58 parturients in whom prenatal diagnosis was performed, PCR was positive in four cases. After birth, six cases of congenital toxoplasmosis were detected by serology.