Small-colony variants and phenotype switching of intracellular Staphylococcus aureus in chronic rhinosinusitis.

BACKGROUND: Chronic rhinosinusitis (CRS) has been linked to the gram-positive bacteria Staphylococcus aureus (S. aureus) in its biofilm or intracellular forms. Recent evidence suggests that S. aureus also exists in a small-colony variant (SCV) form as a mechanism of altering its virulence capabilities. The aim of this study was to investigate the presence of SCVs in sinonasal mucosa of CRS patients and whether the phenomenon of phenotype switching can be applied to intracellular epithelial infections. METHODS: Sinonasal specimens were examined for the presence of intramucosal S. aureus and characterized to the strain level. An airway epithelial cell culture infection model was utilized to investigate whether bacteria were capable of alterations in virulence phenotype. RESULTS: Intramucosal organisms harvested from sinonasal biopsies demonstrate phenotypic growth patterns and lack of coagulase activity consistent with SCVs. Intracellular infection of airway epithelial cell cultures with S. aureus led to decreased secretion of enterotoxins and phenotypic growth alterations consistent with SCVs. CONCLUSIONS: Regulation of S. aureus virulence factors is a dynamic process, and exposure to the intracellular environment appears to provide the necessary conditions to enable these alterations in an attempt for the bacterium to survive and persist within host tissues. Further work is required to ascertain whether SCVs in CRS hold a clinically relevant pathogenic role in recalcitrant disease.

Is nasal steroid spray bottle contamination a potential issue in chronic rhinosinusitis?

BACKGROUND: Intranasal steroids are the first line of treatment for chronic rhinosinusitis. Although contamination of adjunctive devices (e.g. irrigation bottles) has been much investigated, little is known about nasal contamination of the metered-dose spray bottles used to deliver intranasal steroids, and the potential influence on disease chronicity. METHODS: Twenty-five prospectively recruited patients with stable chronic rhinosinusitis underwent microbiological analysis of their nasal vestibule and middle meatus and also of their steroid bottle tip and contents. Additionally, bottle tips were inoculated in vitro with Staphylococcus aureus and various sterilisation techniques tested. RESULTS: For 18 of the 25 (72 per cent) patients, both nasal and bottle tip swabs grew either Staphylococcus aureus or coagulase-negative staphylococci. Staphylococcus aureus was cultured from 7 of the 25 (28 per cent) patients, and 5 of these 7 had concomitant bacterial growth from both nose and steroid bottle. Thus, the cross-contamination rate was 71 per cent for Staphylococcus aureus infected patients and 20 per cent overall. Sterilisation was effective with boiling water, ethanol wipes and microwaving, but not with cold water or dishwashing liquid. CONCLUSION: Nasal steroid spray bottle tips can become contaminated with sinonasal cavity bacteria. Simple sterilisation methods can eliminate this contamination. Patient education on this matter should be emphasised.