This report describes mutations in genes responsible for cell deformities in haemophili under beta-lactam pressure in vitro. Light and transmission electron microscopy confirmed a hypothesis regarding changes in the shape of haemophili that had become more filamentous in the presence of ampicillin (2 mg/L) and cefuroxime (8 mg/L) after 30 days of serial passage. Short-axis size increased by 28% (from 0.767 to 1.06 µm) and long-axis length increased by 54% (from 1 to 2.175 µm). Additionally, whole-genome sequencing analysis (Illumina platform, software PROKKA) revealed a variety of mutations in genes responsible for cell morphology in isolates examined in this study: ftsI (A1576 → C; G1154 → C; T986 → C; G1684 → C), mreB (C476 → T), mreC (A5 → G), mrdA (A1148 → G; C179 → T; G1613 → T), mrdB (T668 → G), mltC (C1016 → T) and rodA (T668 → G). The results of this study indicate that shifts in bacterial shape could play a role in the adaptation of haemophili to a new niche created by beta-lactams as a strategy of antibiotic therapy survival.

Department of Microbiology Faculty of Medicine University Hospital in Pilsen Charles University Pilsen Czech Republic; Biomedical Center Faculty of Medicine Charles University Pilsen Czech Republic

National Reference Laboratory for Antibiotics National Institute of Public Health Prague Czech Republic; Department of Microbiology 3rd Faculty of Medicine Charles University University Hospital Kralovske Vinohrady and National Institute of Public Health Prague Czech Republic

National Reference Laboratory for Electron Microscopy Detection of Infectious Agents National Institute of Public Health Prague Czech Republic

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