Atypical detection of group B Streptococcus ST - 17 clone from a diabetic patient with necrotising fasciitis: A case report

Streptococcus agalactiae or group B Streptococcus (GBS) is among the leading causes of neonatal infections and illnesses in pregnant women, posing a significant health challenge in both high-income and low- to middle-income countries. Predisposing factors in the elderly, such as diabetes mellitus, immunosuppression, obesity, alcoholism, and nicotine addiction, have been cited. Here, we report a 66-year-old diabetic female patient admitted to the hospital with suspected necrotising fasciitis of the left breast, which developed pus-draining lesions. Empiric treatment with amoxicillin-clavulanic acid was initiated. Culture of a swab sample revealed the presence of beta-haemolytic GBS, which was susceptible to ampicillin/penicillin, erythromycin, clindamycin, and vancomycin. The treatment was de-escalated to ampicillin. The outcome was favourable; the patient was discharged after 23 days of admission. Whole genome sequencing revealed the strain to be a hypervirulent clone ST-17, which carried multiple virulence factors and antimicrobial-associated resistance genes. This is the first-ever whole-genome report of hypervirulent GBS ST-17 in our tertiary hospital. This highlights the need for continuous surveillance, as this strain is known for high rates of morbidity and mortality, especially in neonates and the immunocompromised.