Pediatric Bacterial Meningitis Surveillance in Niger: Increased Importance of Neisseria meningitidis Serogroup C, and a Decrease in Streptococcus pneumoniae Following 13-Valent Pneumococcal Conjugate Vaccine Introduction

Abstract

Background: Meningitis is endemic in Niger. Haemophilus influenzae type b (Hib) vaccine and the 13-valent pneumococcal conjugate vaccine (PCV13) were introduced in 2008 and 2014, respectively. Vaccination campaign against Neisseria meningitidis serogroup A was carried out in 2010-2011. We evaluated changes in pathogen distribution using data from hospital-based surveillance in Niger from 2010 through 2016.

Methods: Cerebrospinal fluid (CSF) specimens from children <5 years old with suspected meningitis were tested to detect vaccine-preventable bacterial pathogens. Confirmatory identification and serotyping/grouping of Streptococcus pneumoniae, N. meningitidis, and H. influenzae were done. Antimicrobial susceptibility testing and whole genome sequencing were performed on S. pneumoniae isolates.

Results: The surveillance included 2580 patients with suspected meningitis, of whom 80.8% (2085/2580) had CSF collected. Bacterial meningitis was confirmed in 273 patients: 48% (131/273) was N. meningitidis, 45% (123/273) S. pneumoniae, and 7% (19/273) H. influenzae. Streptococcus pneumoniae meningitis decreased from 34 in 2014, to 16 in 2016. PCV13 serotypes made up 88% (7/8) of S. pneumoniae meningitis prevaccination and 20% (5/20) postvaccination. Neisseria meningitidis serogroup C (NmC) was responsible for 59% (10/17) of serogrouped N. meningitidis meningitis. Hib caused 67% (2/3) of the H. influenzae meningitis isolates serotyped. Penicillin resistance was found in 16% (4/25) of S. pneumoniae isolates. Sequence type 217 was the most common lineage among S. pneumoniae isolates.

Conclusions: Neisseria meningitidis and S. pneumoniae remain important causes of meningitis in children in Niger. The decline in the numbers of S. pneumoniae meningitis post-PCV13 is encouraging and should continue to be monitored. NmC is the predominant serogroup causing N. meningitidis meningitis.

Keywords: N. meningitidis; S. pneumoniae; Niger; cerebrospinal fluid; meningitis.

Figure 1.

Bar graph showing yearly distribution of Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. The line graph on the secondary axis shows the case fatality rate of the 3 pathogens.

Figure 2.

Outcome of meningitis cases by year.

Figure 3.

Maximum likelihood whole genome phylogenetic tree of Streptococcus pneumoniae isolates recovered from cerebrospinal fluid. Tree annotation from left to right: vaccine type; serotype; multilocus sequence type; year of admission; vaccine era (pneumococcal conjugate vaccine); phenotypic antibiotic resistance profiles to chloramphenicol, trimethoprim-sulfamethoxazole (SXT), tetracycline, oxacillin, and erythromycin; and the presence/absence of the antibiotic resistance genes catQ (chloramphenicol), folA/ folP (SXT), tetM (tetracycline), PBP (penicillin), and ermB (erythromycin). Abbreviations: C, chloramphenicol; E, erythromycin; OX, oxacillin; PCV, pneumococcal conjugate vaccine; SXT, trimethoprim-sulfamethoxazole; TE, tetracycline.