Although swabs are relatively simple to use, absorbency of infected material is variable and adequate material collection that is representative of pathogenic changes, for example to wounds, is often dependent upon correct sampling technique (Gould and Brooker [75], Panpradist et al. [181]). Swab specimens should be collected using an aseptic technique with sterile swabs, with the principal aim of gathering as much material as possible from the site of infection or inflammation. Care should be taken to avoid contamination with anything other than the sample material, such as surrounding tissue, which will be contaminated with other pathogens such as skin flora (Weston [255]).

If an infected area is producing copious amounts of pus or exudate, a specimen should be aspirated using a sterile syringe because swabs tend to absorb excess overlying exudate, resulting in an inadequate specimen (Huddleston Cross [97]). If the area to be swabbed is relatively dry (e.g. in nasal or skin swabs), the tip of the swab can be moistened with sterile 0.9% sodium chloride, which makes it more absorbent and increases the survival of pathogens (Weston [255]).

Obtaining a swab should be considered in conjunction with a comprehensive nursing assessment. This could include observation of localized infection, such as inflammation or discharge from a wound during a dressing change.

Practitioners should know what type of pathogenic micro‐organism they are testing (e.g. whether a bacterial or viral infection is suspected), as this will determine which swab is the most appropriate. Advice should be sought from the microbiology laboratory prior to taking a swab to ensure appropriate and resource‐effective sampling or specimen collection. For example, while viruses cause the majority of throat infections, group A streptococcus is the main bacterial cause of sore throats and therefore, if suspected, a swab with bacterial transport medium would need to be used rather than one containing viral transport medium (PHE [185]).