Aims: The present study investigated receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG), and Runt-related transcription factor 2 (RUNX2) gene expressions in giant cell tumour of bone (GCTB) patients in relationship with tumour recurrence. We also aimed to investigate the influence of CpG methylation on the transcriptional levels of RANKL and OPG.Methods: A total of 32 GCTB tissue samples were analyzed, and the expression of RANKL, OPG, and RUNX2 was evaluated by quantitative polymerase chain reaction (qPCR). The methylation status of RANKL and OPG was also evaluated by quantitative methylation-specific polymerase chain reaction (qMSP).Results: We found that RANKL and RUNX2 gene expression was upregulated more in recurrent than in non-recurrent GCTB tissues, while OPG gene expression was downregulated more in recurrent than in non-recurrent GCTB tissues. Additionally, we proved that changes in DNA methylation contribute to upregulating the expression of RANKL and downregulating the expression of OPG, which are critical for bone homeostasis and GCTB development.Conclusion: Our results suggest that the overexpression of RANKL/RUNX2 and the lower expression of OPG are associated with recurrence in GCTB patients.Cite this article: Bone Joint Res 2024;13(2):84–91.

Background: The spread of extended-spectrum β-lactamase-producing Klebsiella is an emerging public health concern presenting severe clinical impacts. This problem is particularly severe in developing countries where irrational use of antibiotics makes the treatment of such infections more challenging. Methods: In this cross-sectional study, we investigated antibiotic resistance among clinical Klebsiella pneumoniae isolates from 256 patient specimens from Al-Diwaniyah hospitals, using standard microbiological methods followed by PCR. Antimicrobial susceptibility testing identified resistance rates and proportions of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. Carbapenemase genes were detected by multiplex PCR and sequencing. Mutations were characterized, and their functional significance was predicted using in silico prediction tools. Results: Fifty Klebsiella pneumoniae isolates were recovered, exhibiting high resistance rates (42–100%) to penicillins, cephalosporins, fluoroquinolones and carbapenems, with 62% classified as MDR and 38% as XDR. Carbapenemase genes were highly prevalent (blaOXA-48 56%, blaIMP 44%, blaVIM 30%, blaKPC 28%, blaNDM 26%), with 60% of isolates co-harbouring ≥ two genes. Most mutations were predicted to be structurally tolerated, while active-site-proximal substitutions (H120L in NDM-52 and V120L in OXA-48) were predicted to affect enzyme activity. However, docking analysis suggested no significant alteration in carbapenem binding affinity. Conclusions: Our results highlight a very high prevalence of MDR/XDR Klebsiella pneumoniae, associated with diverse carbapenemase genes and resistance-related polymorphisms that may indicate potential functional impacts. To the best of our knowledge, this is the first study in Iraq to combine carbapenemase gene mutation analysis with structural modelling and molecular docking. This study emphasizes the urgent need for effective antimicrobial resistance surveillance in Iraq.