Evaluation of an autoclave resistant anatomic nose model for the testing of nasal swabs

Abstract

A nose model that allows for the comparison of different modes of sample acquisition as well as of nasal swab systems concerning their suitability to detect defined quantities of intranasal microorganisms, and further for training procedures of medical staff, was evaluated. Based on an imprint of a human nose, a model made of a silicone elastomer was formed. Autoclave stability was assessed. Using an inoculation suspension containing Staphylococcus aureus and Staphylococcus epidermidis, the model was compared with standardized glass plate inoculations. Effects of inoculation time, mode of sampling, and sample storage time were assessed. The model was stable to 20 autoclaving cycles. There were no differences regarding the optimum coverage from the nose and from glass plates. Optimum sampling time was 1 h after inoculation. Storage time after sampling was of minor relevance for the recovery. Rotating the swab around its own axis while circling the nasal cavity resulted in best sampling results. The suitability of the assessed nose model for the comparison of sampling strategies and systems was confirmed. Without disadvantages in comparison with sampling from standardized glass plates, the model allows for the assessment of a correct sampling technique due to its anatomically correct shape.

Keywords: Staphylococcus aureus; autoclave resistant; hygiene testing; nose model; swab.

Fig. 1.

(a) Front view of the silicone elastomer nose model for standardized testing of swabs. (b) Posterior view. Posterior openings of the nostrils allow for a connection with a vacuum pump for simulated “inhalation” experiments with sedimentation of aerosolized pathogens

Fig. 2.

Effects of sample storage after sampling for up to 24 h. Pooled data are shown, comprising results of four independent experiments, each including 25 inoculated nose models. Inoculation of the nose models was performed with a 100-fold concentrated standard suspension containing S. aureus and S. epidermidis. The inoculated S. epidermidis concentration was 100-fold higher than the S. aureus concentration. The bars indicate mean recovery proportions (in percent, ± standard deviation [SD]) of S. aureus and S. epidermidis after storage for several hours (n = 20 per experiment) in comparison to immediate cultural growth after swabbing (n = 5 per experiment)