Meningococcal infections in Oman (2000–2025): National trends in serogroup dynamics, age-group vulnerability, antimicrobial resistance, clinical characteristics, and outcomes

BACKGROUND: Invasive meningococcal disease (IMD) remains a major cause of bacterial infections with high mortality and long-term complications. Understanding its epidemiology is crucial for prevention, vaccination strategies, and clinical management. This study describes 25-year national trends in serogroup distribution, age-specific vulnerability, clinical characteristics, outcomes, and antimicrobial susceptibility in Oman. METHODS: This retrospective study included all laboratory-confirmed Neisseria meningitidis cases reported to the Central Public Health Laboratory, Oman, from January 2000 to June 2025. Demographic, clinical, and microbiological data were extracted from medical records. Serogrouping was performed using slide agglutination or PCR, and antimicrobial susceptibility testing followed CLSI guidelines. RESULTS: Ninety-six patients with 101 samples were included. Median age was 14 years; infants < 1 year accounted for 26%. Males comprised 68.8%, and Omani nationals 91.7%. Serogroup W was most prevalent (40.6%), followed by B (21.9%), with non-groupable strains represented 24%. Invasive infections accounted for 82.3%, predominantly associated with serogroup W, while non-groupable strains were linked to localized infections. Overall mortality was 16.7%, significantly associated with complications and HD/ICU admission. All isolates were susceptible to ceftriaxone, cefotaxime, meropenem, rifampin, chloramphenicol, and azithromycin. Susceptibility rates were reduced for penicillin (46.8%) and co-trimoxazole (12.5%), while ampicillin susceptibility was 81.3%. Fluoroquinolone susceptibility was 73.2% for ciprofloxacin and 63.2% for levofloxacin, with notably lower rates observed among non-groupable strains. A recent rise in cases peaked in early 2025, with serogroup W accounting for the majority of recent isolates. CONCLUSIONS: N. meningitidis remains a significant cause of invasive infections in Oman, especially in infants and young children. Serogroup W predominates and is associated with invasive disease. Emerging penicillin and fluoroquinolone resistance underscores the need for ongoing surveillance and supports inclusion of MenACWY and MenB vaccines in the national program. Strengthening laboratory capacity and regional data sharing is essential for early detection and outbreak prevention.