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

Bartolitius, Lennart; Frickmann, Hagen; Warnke, Philipp; Ottl, Peter; Podbielski, Andreas

doi:10.1556/eujmi-d-14-00020

Cited by 3 publications

(5 citation statements)

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“…In addition, in the present study sampling with moistened and dry swabs was assessed under identical laboratory conditions utilizing an anatomically correct artificial model of a human nose [ 29 ]. Recently, this model had successfully been used for device testing and teaching of medical staff in terms of MRSA sampling [20;30].…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2016

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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.

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Section: Discussionmentioning

confidence: 99%

“…For in vitro experiments, artificial, autoclave resistant, silicone nose models, based on an imprint of a human nose [ 29 ], were inoculated with a numerically defined amount of MRSA and subsequently swabbed. Four different swab types were tested.…”

Section: Methodsmentioning

confidence: 99%

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

et al. 2016

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“…To address both points, the present study utilizes an artificial, anatomically correct model of a human nose [21] , [24] inoculated with numerically defined quantities of MRSA and S. epidermidis . For S. aureus , ST22-MRSA-IV strain, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…Yet, clinical swab studies have to deal with these inter-individual differences concerning anatomy, surface-moisture, or bacterial densities in patients' noses and therefore can hardly be standardized. To address these issues this study followed a new approach by utilizing a recently introduced, anatomically correct, artificial nose model [21] , [24] inoculated with a defined mixture of MRSA and S. epidermidis to analyze bacterial recovery rates from different swab-types by direct plating and after elution into Amies medium, respectively. Thus, anatomical and mechanical challenges as well as a high degree of laboratory reproducibility are combined in a nasal MRSA-screening study for the first time.…”

Section: Introductionmentioning

confidence: 99%

Nasal Screening for MRSA: Different Swabs – Different Results!

et al. 2014

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ObjectivesSwab-based nasal screening is commonly used to identify asymptomatic carriage of Staphylococcus aureus in patients. Bacterial detection depends on the uptake and release capacities of the swabs and on the swabbing technique itself. This study investigates the performance of different swab-types in nasal MRSA-screening by utilizing a unique artificial nose model to provide realistic and standardized screening conditions.MethodsAn anatomically correct artificial nose model was inoculated with a numerically defined mixture of MRSA and Staphylococcus epidermidis bacteria at quantities of 4×102 and 8×102 colony forming units (CFU), respectively. Five swab-types were tested following a strict protocol. Bacterial recovery was measured for direct plating and after elution into Amies medium by standard viable count techniques.ResultsMean recovered bacteria quantities varied between 209 and 0 CFU for MRSA, and 365 and 0 CFU for S. epidermidis, resulting swab-type-dependent MRSA-screening-sensitivities ranged between 0 and 100%. Swabs with nylon flocked tips or cellular foam tips performed significantly better compared to conventional rayon swabs referring to the recovered bacterial yield (p<0.001). Best results were obtained by using a flocked swab in combination with Amies preservation medium. Within the range of the utilized bacterial concentrations, recovery ratios for the particular swab-types were independent of the bacterial species.ConclusionsThis study combines a realistic model of a human nose with standardized laboratory conditions to analyze swab-performance in MRSA-screening situations. Therefore, influences by inter-individual anatomical differences as well as diverse colonization densities in patients could be excluded. Recovery rates vary significantly between different swab-types. The choice of the swab has a great impact on the laboratory result. In fact, the swab-type contributes significantly to true positive or false negative detection of nasal MRSA carriage. These findings should be considered when screening a patient.

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“…The lack of standardization of screening assays targeting MDR bacteria, that means the lack of optimization and adaptation of diagnostic test assays in a way that they reproducibly lead to the same results with identical samples, is problematic. While swabbing techniques and the kind of used swabs affect the sensitivity of screening for MRSA ( Bartolitius et al, 2014 ; Warnke et al, 2014a , b , c ), even basal questions like the need for broth enrichment ( Murk et al, 2009 ; Jazmati et al, 2016 ), required assessment strategies, and the number of samples ( Ho et al, 2012 ; Vrioni et al, 2012 ; Rybczynska et al, 2014 ; Al-Bayssari et al, 2015 ) are under debate for screening for colonizers of the gut like vancomycin-resistant Enterococcus spp. or beta-lactam-resistant Enterobacteriaceae.…”

Section: Methodical Issuesmentioning

confidence: 99%

More Pathogenicity or Just More Pathogens?—On the Interpretation Problem of Multiple Pathogen Detections with Diagnostic Multiplex Assays

et al. 2017

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Modern molecular diagnostic approaches in the diagnostic microbiological laboratory like real-time quantitative polymerase chain reaction (qPCR) have led to a considerable increase of diagnostic sensitivity. They usually outperform the diagnostic sensitivity of culture-based approaches. Culture-based diagnostics were found to be insufficiently sensitive for the assessment of the composition of biofilms in chronic wounds and poorly standardized for screenings for enteric colonization with multi-drug resistant bacteria. However, the increased sensitivity of qPCR causes interpretative challenges regarding the attribution of etiological relevance to individual pathogen species in case of multiple detections of facultative pathogenic microorganisms in primarily non-sterile sample materials. This is particularly the case in high-endemicity settings, where continuous exposition to respective microorganisms leads to immunological adaptation and semi-resistance while considerable disease would result in case of exposition of a non-adapted population. While biofilms in chronic wounds show higher pathogenic potential in case of multi-species composition, detection of multiple pathogens in respiratory samples is much more difficult to interpret and asymptomatic enteric colonization with facultative pathogenic microorganisms is frequently observed in high endemicity settings. For respiratory samples and stool samples, cycle-threshold-value-based semi-quantitative interpretation of qPCR results has been suggested. Etiological relevance is assumed if cycle-threshold values are low, suggesting high pathogen loads. Although the procedure is challenged by lacking standardization and methodical issues, first evaluations have led to promising results. Future studies should aim at generally acceptable quantitative cut-off values to allow discrimination of asymptomatic colonization from clinically relevant infection.

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

Cited by 3 publications

References 8 publications

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

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

Nasal Screening for MRSA: Different Swabs – Different Results!

More Pathogenicity or Just More Pathogens?—On the Interpretation Problem of Multiple Pathogen Detections with Diagnostic Multiplex Assays

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