Penicillin-resistant beta-haemolytic Group B Streptococcus isolated from a urinary tract infection in a non-pregnant adult
DOI:
https://doi.org/10.63719/imrj.2026.12.02.001Keywords:
Streptococcus agalactiae, Group B Streptococcus, urinary tract infection, penicillin resistance, antimicrobial resistanceAbstract
Streptococcus agalactiae (Group B Streptococcus, GBS) is an established cause of urinary tract infections (UTIs) and is typically susceptible to penicillin. However, although rare, resistance to beta-lactam antibiotics is increasingly reported and may complicate treatment in adults. Early identification of resistant strains is essential to guide appropriate antimicrobial therapy. We report a case of a 54-year-old non-pregnant woman with diabetes mellitus (DM) who presented with symptomatic UTI. Urine culture yielded beta-haemolytic GBS at >10⁵ CFU/mL. Initial empirical treatment with amoxicillin-clavulanate was ineffective. Antimicrobial susceptibility testing (AST) demonstrated resistance to penicillin. The isolate was identified as S. agalactiae by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS), and susceptibility testing was performed in accordance with the latest Clinical and Laboratory Standards Institute (CLSI) guidelines. Following the susceptibility results, therapy was switched to intravenous ceftriaxone, resulting in complete clinical resolution of symptoms. This case highlights the clinical importance of emerging beta-lactam resistance in GBS urinary infections in non-pregnant adults and emphasises the significance of culture-directed therapy. Although phenotypic resistance was confirmed, the absence of molecular characterisation warrants cautious interpretation given the rarity of penicillin-resistant GBS. Continued surveillance is necessary to monitor resistance trends and guide treatment strategies.
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Copyright (c) 2026 Yaminie Nair A Mahdavan, Yii Ling Liow, Sharlini Devi Guna Segaran, Shabhina Baghauan, Habib Esa Hakim (Author)
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