Utilizing Moist or Dry Swabs for the Sampling of Nasal MRSA Carriers? An In Vivo and In Vitro Study

Abstract

This study investigates the quantitative bacterial recovery of Methicillin-resistant Staphylococcus aureus (MRSA) in nasal screenings by utilizing dry or moistened swabs within an in vivo and an in vitro experimental setting. 135 nasal MRSA carriers were each swabbed in one nostril with a dry and in the other one with a moistened rayon swab. Quantitative bacterial recovery was measured by standard viable count techniques. Furthermore, an anatomically correct artificial nose model was inoculated with a numerically defined suspension of MRSA and swabbed with dry and moistened rayon, polyurethane-foam and nylon-flocked swabs to test these different settings and swab-materials under identical laboratory conditions. In vivo, quantities of MRSA per nostril in carriers varied between <101 and >107 colony forming units, with a median of 2.15x104 CFU. However, no statistically significant differences could be detected for the recovery of MRSA quantities when swabbing nasal carriers with moist or dry rayon swabs. In vitro testing confirmed the in vivo data for swabs with rayon, polyurethane and nylon-flocked tips, since pre-moistening of swabs did not significantly affect the quantities of retrieved bacteria. Therefore, pre-moistening of swabs prior to nasal MRSA sampling provides no advantage in terms of recovering greater bacterial quantities and therefore can be omitted. In addition, this situation can be mimicked in an in vitro model, thereby providing a useful basis for future in vitro testings of new swab types or target organisms for screening approaches.

A Clinical Trial to Evaluate the Efficacy of α-Viniferin in Staphylococcus aureus – Specific Decolonization without Depleting the Normal Microbiota of Nares

“…We also evaluated the effect of α-viniferin against normal nasal microflora using NGS, where NGS upgrades DNA sequencing methodology to the next level through parallel sequencing processes that enable the simultaneous sequencing of different DNA fragments while providing precise identification results ( Abayasekara et al 2017 ). The NGS results demonstrated Staphylococcus as the most dominant group in the anterior nares, supporting similar published findings ( Hogan et al 2016 ; Warnke et al 2016 ; Lu et al 2018 ). α-Viniferin drastically reduced the number of Staphylococcus in the anterior nares, while the decrease in the number of other bacteria groups was statistically insignificant.…”

Development and Evaluation of a Sensitive Bacteriophage-Based MRSA Diagnostic Screen

“…This limit of detection is similar to previously described PCR-based screens [ 16 , 19 ]. The median burden of MRSA recovered from nasal swabs of carriers has been found to be greater than 10,000 CFU [ 50 ]. Additionally, individuals with high burdens of nasal colonization are more likely to carry MRSA at multiple body sites and be vectors for transmission [ 51 , 52 ].…”

Staphylococcus aureus Nasal Colonization: An Update on Mechanisms, Epidemiology, Risk Factors, and Subsequent Infections

“…In order to confirm nasal carriage of S. aureus , samples are commonly collected using commercial dry or moistened sterile swabs, with no significant difference found between the two ( Warnke et al, 2016 ). The protocol of sampling is not really standardized but generally consists of rubbing the swab in the anterior nares of each nostril for approximately four rotary movements ( Wertheim et al, 2006 ; Bode et al, 2010 ).…”