Invasive group B Streptococcus infections in non-pregnant adults: Clinical features and antibiotic resistance at the Avicenne military hospital of Marrakesh (2020–2025)

Background: Group B Streptococcus (GBS) or Streptococcus agalactiae is a type of Gram-positive β-hemolytic coccus which is increasingly regarded as a cause of invasive infections in non-pregnant adults with. It is generally associated with neonatal disease but in recent decades its epidemiological profile has shifted towards adult patients. Objective: To establish the clinical and antimicrobial susceptibility profiles of invasive GBS (iGBS) infections among non-pregnant adults at the Avicenna Military Hospital of Marrakech between January 2020 and May 2025. Methods: A retrospective, descriptive study was conducted using laboratory records. Non-pregnant adult patients (≥18 years) with confirmed GBS isolates from sterile or clinically significant non-sterile sites were included. Bacterial identification was performed using. Resistance phenotypes were established by determining CMIs using the BD Phoenix™ M50 system or by using antibiotic disk diffusion method, following EUCAST guidelines. Results: Over a period of 53 months, we observed 72 cases of invasive GBS with a striking predominance of males (90.2%). The most frequent clinical infections included urinary tract infections (56.8%), skin and soft tissue infections (27.0%), and pneumonia (8.1%). All the isolates were sensitive to penicillin G, vancomycin and linezolid. As for tetracycline a high resistance rate was noted (73.5%). Moderate resistance rates to erythromycin (24.2%) and clindamycin (22%) were observed. Conclusion: GBS is an emerging cause of invasive infections in non-pregnant adults. It has different clinical manifestations ranging from urinary tract infections to bacteremia and meningitis. Although first-line antibiotics such as penicillin remain effective, the significant resistance rate to macrolides and tetracyclines highlights the need for a continuous epidemiological surveillance and cautious empirical treatment, particularly in patients with a penicillin allergy.