Staphylococcus aureus (SA) is a facultative anaerobic Gram-positive coccus, found in 30% to 50% of the healthy adult population. It is considered to be a commensal organism of humans and around 20% of individuals are ‘persistent carriers’. The organism resides most commonly in the anterior nares, where there is a relative absence of immunological defences and colonisation is achieved through bacterial adherence to the surface membrane of the host cells. Other common sites include the axillae, vagina and pharynx. SA is responsible for a diverse range of diseases; from skin and soft tissue infection, pneumonia and gastrointestinal (GI) poisoning, to fatal conditions of bacteraemia, endocarditis, sepsis and toxic shock syndrome. Within cystic fibrosis (CF), SA is the most commonly isolated organism, where more than half of US individuals had at least one culture positive for methicillin sensitive SA in 2017 and its occurrence, was highest in those younger than 10. Controversies remain ongoing regarding its clinical significance in early and adult lung pathology, as well as optimal treatments regimens in these populations. In a seminal review by Wong and colleagues, the authors highlighted the need for further investigations to help understand (i). the early host immune response that enables SA to reside within the CF lung, (ii) to determine if there are organism specific factors that are associated with CF lung disease and (iii) to clarify the utility of anti-staphylococcal antibiotic prophylaxis and/or eradication in the treatment of this patient population. Therefore, robust and reliable methods for the laboratory detection of SA are needed to support the evidence for SA involvement in lung disease. It was the aim of this study to (i). compare the optimum agar to recover SA from CF sputum and (ii). compare selective enrichment versus non-enrichment for the recovery of SA from CF sputa.
Wen, H., Stirling, J., McCaughan, J., Schock, B., Downey, D. G., Ennis, M., & Moore, J. E. (2019). Improved culture detection of Staphylococcus aureus from sputum of patients with cystic fibrosis (CF). Journal of Clinical Pathology, jclinpath-2019-206059. https://doi.org/10.1136/jclinpath-2019-206059