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Analytical performance evaluation of a new homogenization system
for tissue biopsies
Aurélie Scherler1* & Antony Croxatto1
1. Département de Microbiologie, Fondation Admed, La Chaux-de-Fonds, *Presenting author: aurelie.scherler@ne.ch
.
1. Introduction
Diagnostics of infections from solid tissues require accurate microbiological diagnostics with careful approaches for sampling, pre-
analytical processing and diagnostic analysis. To increase the diagnostic accuracy, pre-processing steps are implemented such as
homogenization or grinding of tissue, which improve microbial release from the specimens1.
A new homogenization system has recently entered the market with two separate components:
• ProbeAX Evolution: Single-use sampling tube designed with a ceramic block featuring a rough surface and a stainless steel grater
integrated into the tube lid.
• SpinAX Instrument: Rotation at high speed (2200 rpm) with an oscillating motion, generating a grinding action of the sample
between the ceramic block and the metal grater.
This grating process effectively breaks down tissue, disrupts biofilms, and releases bacteria or fungi into the physiological solution. The ProbeAX Evolution tube
resulting solution can be utilized for cultivation on agar plates, enrichment broths, or molecular diagnostics of pathogenic organisms. with SpinAX Instrument
2. Aim & Methods
Aim: Assess analytical performance of a new homogenization system for tissue specimens, the SpinAX/ProbeAX Evolution system (Axonlab, Switzerland), in
comparison with Ultra-TurraX® Tube Drive (IKA, Germany)/ProbeAX tubes (Axonlab, Switzerland) system as a reference method.
Two types of tissues samples were compared:
• Soft tissue (fibrous and connective tissue)
• Hard tissue (tendon, cartilage, bone)
Patient biopsies were split into two parts to be processed with either SpinAX or Ultra-
TurrAX system. Then we performed:
• Gram stained cell counting according to quantity of cells or bacteria per microscopy
field.
• Semi-quantitative 4-quadrant measurement of bacterial growth on four types of
media plates (chocolate-, chromogenic-, blood- and Schaedler agar) and on
Thioglycolate (THIO).
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media plates (chocolate-, chromogenic-, blood- and Schaedler agar) and on
Thioglycolate (THIO).
Growth was ranked from 0 (no growth) to 4 (growth in the 4th quadrant). Growth was
defined as superior/inferior if growth rank of the two systems differed by > 1 or when
there was no growth with one method and growth with the other.
3. Results
A
1 total of 95 clinical samples biopsies, including 31 hard and 64 soft tissue, from 49 patients were analyzed in this study.
Gram staining cell count was similar for 73 % (154/210) of the observed cell Among the positive tissues samples, 94 bacterial and yeast species were
types (Gram-positive cocci (GPC), Gram-negative bacilli (GNB), erythrocytes, recovered.
leucocytes, epithelial cells) in all specimen. The remaining observations
were possible with SpinAX only in 20 % (42/210) or UT only in 7 % (14/210). 2. Assessment of growth et recovery of the clinical isolates
Microorganisms or host cells were not detected in 10 samples following
SpinAX Ultra-TurrAX
Ultra-TurrAX homogenization, with GPC not observed in five samples and Nb sample
N° (%) N° (%)
GNB in two samples.
Global growth
1. Percentage of positivity and negativity with both homogenization systems Similar 84 (89.4%) 84 (89.4%)
94
Better 4 (4.3%) 6 (6.4%)
SpinAX Ultra-TurrAX
Nb sample Clinical isolates
N° (%) N° (%)
Samples Recovered 84 (89.4%) 83 (88.3%)
94
Positive samples 42 (44.2%) 39 (41.1%) Not rec
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83 (88.3%)
94
Positive samples 42 (44.2%) 39 (41.1%) Not recovered 10 (10.6%) 11 (11.7%)
95
Negative samples 53 (55.8%) 56 (58.9%)
Clinical isolates of Staphylococcus aureus from 3 samples were recovered
False negative samples 0 (0%) 3 (3.2%) with the SpinAX but not with the Ultra-TurrAX system.
Bacterial growth detected in 42/95 samples (44.2 %) from 26 patients.
4. Conclusions
• Possible better detection of microorganisms and host cells by Gram • Overall, the SpinAX homogenization is thus providing an overall similar
staining microscopy with SpinAX. performance than Ultra-TurrAX with a possible better homogenization and
• 89.4% of the specimen showing similar bacterial growth with both ultra-structure preservation for Gram staining microscopy.
systems Discrepancies probably explained by biological variation of the • Additional advantages of the SpinAX:
microbial load not uniformly distributed in a tissue sample. - Absence of aggregates after homogenization Easier pipetting of the
SpinAX supernatant
- Less noise during the SpinAX grinding and homogenizing
Reference: 1. S. Redanz et al. Diagn Microbiol Infect Dis. (2015)