Genetic Determinants and Clonal Composition of Levofloxacin-Resistant Streptococcus agalactiae Isolates from Bulgaria
Abstract
Background: Levofloxacin is a broad-spectrum third-generation fluoroquinolone with bactericidal activity against Streptococcus species. We aimed to investigate the susceptibility rates of levofloxacin, the genetic determinants contributing to resistance, the serotype distribution, and the population structure of levofloxacin-resistant Streptococcus agalactiae (GBS) isolates. Methods: Antibiotic susceptibility testing was conducted according to the EUCAST criteria. PCR-serotyping, determination of mutations in the quinolone resistance-determining regions (QRDRs), and multi-locus sequence typing (MLST) were performed on all levofloxacin-resistant strains. Results: Among the 328 GBS isolates, 11.9% exhibited resistance to levofloxacin. We categorized the samples into two main groups: vaginal (64.1%) and extra-vaginal. The latter was further subdivided into invasive (10.3%) and non-invasive (25.6%) ones. The most common serotypes identified were V (30.8%) and III (25.6%). All examined resistant strains possessed missense mutations in the QRDR of parC (Ser79Phe/Tyr and Asp83Asn), whereas 59.0% of them exhibited additional mutation in gyrA (Ser81Leu and Glu85Lys/Ala). The MLST results disclosed six clonal complexes: CC19(64.1%), followed by CC1 (10.3%), CC452 (7.7%), and CC459 (5.1%), and CC12 and CC23, represented by single strains. Conclusions: We observed a growing resistance to fluoroquinolones that appears to exceed the average in Europe. More than half of the isolates…
Read the paper
Related studies
- Ferulic acid regulates the AKT/GSK-3β/CRMP-2 signaling pathway in a middle cerebral artery occlusion animal model
- Novel Pharmacokinetic/Pharmacodynamic Parameters Quantify the Exposure–Effect Relationship of Levofloxacin against Fluoroquinolone-Resistant Escherichia coli
- Photochemical behavior of levofloxacin
- Correlation Between Dissolution Profiles of Salt-Form Drugs in Biorelevant Bicarbonate Buffer and Oral Drug Absorption: Importance of Dose/ Fluid Volume Ratio
- Evaluation of the synergistic potential and mechanisms of action for de novo designed cationic antimicrobial peptides
- Synthesis of [11C]levofloxacin
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.