Nasal colonisation with Staphylococcus aureus increases the risk of staphylococcal infections at other sites of the body such as postoperative wounds and dialysis access sites. It is also associated with recurrent skin infections and nosocomial infections in nurseries and hospital wards. S. aureus is a major cause of morbidity and mortality in haemodialysis patients as most patients carry the organism in their anterior nares.

Eradication of nasal carriage of S. aureus may be beneficial in certain clinical conditions such as recurrent furunculosis. Systemic, in addition to topical, treatment is appropriate for nasally colonised patients who have infection elsewhere. Topical antibacterial agents such as mupirocin and chlorhexidine/neomycin are preferred to systemic formulations when a patient is identified as a carrier. Nose swabs may be used to investigate carriage of Lancefield group A streptococcus and Methicillin Resistant Staphylococcus aureus (MRSA) (Please see Investigation of specimens for screening for MRSA).

There is no clear evidence regarding the significance of isolating Haemophilus influenzae and Streptococcus pneumoniae from nose swabs as a predictor of involvement in infections such as sinusitis.

Although nose swabs are not the ideal specimen for the examination of nasal discharge, they are sometimes received. Nasal discharge may be a presentation of diphtheria. However, nose swabs are not routinely cultured for Corynebacterium diphtheriae. Nasal swabs should not be taken to investigate the presence of Bordetella pertussis. Rhinoscleroma, due to infection with Klebsiella rhinoscleromatis, is a rare form of chronic granulomatous nasal infection affecting the nasal passages and sinuses which can also include the pharynx and larynx. The disease is progressive and manifests itself by tumour-like growths with local extension. Although common in Eastern Europe, Central Africa, Latin America and South East Asia, rhinoscleroma appears to be poorly communicable. Ozaenia (ozena) is a chronic atrophic rhinitis. The condition can destroy the mucosa and is characterised by a chronic, purulent and often foul-smelling nasal discharge. Klebsiella ozaenae may have an etiological role.