In the final issue of the JHI for 2021, an editorial by the JHI team discusses the new evidence presented in the recent Joint Healthcare Infection Society and Infection Prevention Society guidelines for the prevention and control of MRSA in healthcare facilities. The guidelines remain free to read and download in the journal. Also on the topic of MRSA, original research from Kinnevey et al. investigate MRSA transmission among healthcare workers, patients and the environment in a large acute hospital under non-outbreak conditions using whole-genome sequencing. Other articles included in the December edition include a systematic review of whether pulsed lavage reduces the risk of surgical site infection from Bath et al., and a narrative review from Le Guern et al. on colonization resistance against multi-drug-resistant bacteria. Research articles this month compare the impact of left- vs. right-sided insertion of catheters in catheter-associated bloodstream infection in patients with cancer (Jones et al.; also the subject of a blog from the Healthcare Infection Society), ask whether chlorine dioxide is a more potent antiviral agent against SARS-CoV-2 than sodium hypochlorite (Hatanaka et al.) and study the transmission of extended-spectrum β-lactamase-producing Klebsiella pneumoniae as associated with sinks in a surgical hospital ward (Nakanura et al.).