Rapid antimicrobial susceptibility testing

Highly sensitive measurements of bacterial responses to single or combination testing of antibiotic efficacy – a new level of accuracy and speed in monitoring life and death

  • Direct metabolic readout in real-time without labeling or additions
  • Phenotypic responses that provide exact behavior of susceptible and resistant isolates
  • Fast detection time for rapid diagnosis
  • Continuous and quantitative visualization of the bactericidal and bacteriostatic effects
  • Versatile combination testing of antibiotics for AST

Thermogram

calScreener™ raw data

A graph showing how the raw data from the calScreener looks

Heat over time curve

Integrated data, equivalent to bacterial growth curve

A graph showing the integrated data, equivalent to bacterial growth curve

Escherichia coli planktonic growth in Mueller Hinton media. Normalized data vs control.

CalScreener measures the power produced from the sample in Joules per second or µW and gives a specific curve dependent on the specimen and the culture media. When CalScreener data is integrated over time the heat over time curve matches the conventional density growth curves from which the growth parameters can be calculated. Parameters such as maximum growth rate (the slope of the log phase in h-1) and the total biomass of the culture (Peak power in µW).

Antibiotic resistance is one of the greatest threats to humanity

Common human pathogens are becoming increasingly multiresistant. There is a pressing need for new antibiotics and faster diagnostic methods, in particularly novel methodology for testing multiple antibiotics in combination.

The classical AST methods such as broth microdilution (BMD) or disk diffusion have major limitations such us time and cost to results, but they also require large amounts of viable bacteria, analyses are restricted to a limited organism spectrum, sample processing is complex and results are based on subjective interpretation.

Symcel will change the management paradigm of AST by enabling customized solutions with rapid and accurate quantitative measurements. We bring solutions to this problem.

We measure life and death with precision

Direct metabolic readout – we measure the signature of life by monitoring metabolic changes of bacteria exposed to antibiotics, calScreener™ is the only solution that can do this and provide growth kinetics and long-term cell viability readouts

Define efficient combination treatments

A limited number of antimicrobials are available, and there is no commercial solution for combination therapy testing.  We will set a new gold standard for combination testing

High sensitivity­­ gives accurate data

The calScreener has a very high sensitivity and continuously monitors the metabolic response of bacteria exposed to antibiotics

Fast and real-time responses

Antibiotic susceptibility in less than 8 hours and the correct measurement of the cell kill- and inhibitory effects on bacteria means no false responses due to cell debris or lysed cells

Fast antimicrobial susceptibility determination

Graph displaying the dose dependency of antibiotic (AB) treatment and calculation of the minimum inhibitory concentration (MIC) with the calScreener (y axis heat flow and x axis time)

Early cutdown of the graph below

With calScreener early differences in growth can be detected, significantly reducing the time for AST and generating more reliable readout.

Currently, Symcel is clinically validating the calScreener to reduce the time for AST to 6 hours or less.

Read more about the H2020 project

Graph displaying the dose dependency of antibiotic (AB) treatment and calculation of the minimum inhibitory concentration (MIC) with the calScreener (y axis heat flow and x axis time)
Graph displaying the dose dependency of antibiotic (AB) treatment and calculation of the minimum inhibitory concentration (MIC) with the calScreener (y axis heat in joules and x axis time)

Escherichia coli planktonic growth in Mueller Hinton media, same experimental conditions as for BMD. Normalized data vs. control.

calScreener can be run as long as needed for the specific application and get a detailed metabolic behavior of the specimen.

In these graphs, the dose dependency of the antibiotic (AB) treatment can be objectively observed, and calculation of the minimum inhibitory concentration (MIC) with calScreener becomes a reliable and objective determination since it is not prone to false positive signals such as cell debris or metabolic inactive bacteria.

Versatile AST determination with any mono or combination antibiotic therapy 

Graph displaying the lack of effect when a single antibiotic is used and the clear additive effect when using the combination of antibiotics.
Graph displaying the lack of effect when a single antibiotic is used and the clear additive effect when using the combination of antibiotics.

Klebsiella pneumoniae planktonic growth in Mueller Hinton media, same experimental conditions as for BMD.

Calscreener™ gives completely flexibility regarding the single or combo treatment, making AST most flexible and relevant. 

In these graphs, it can be observed the lack of effect in the metabolism of the culture of the single antibiotic used. However, there is a clear additive effect when using the combination of antibiotics in the bacterial metabolism. Prolonged observation of the activity makes it possible to study re-growth, biofilm formation and late-stage survival of population subsets.

The bacterial species and strain give rise to unique metabolic thermograms

P. aeruginosa

Heat flow graph showing the unique footprint of P. aeruginosa

A. Baumannii

Heat flow graph showing the unique footprint of A. Baumannii

K. pneumoniae

Heat flow graph showing the unique footprint of K. pneumoniae

E. coli

Heat flow graph showing the unique footprint of E. coli
Heat flow graph showing the unique footprint of different species
Heat graph showing the unique footprint of different species

Bacterial planktonic growth in Mueller Hinton media, same experimental conditions as for BMD. 

The unique heat flow footprint obtained in calScreener is dependent on the metabolism of the specimen, and this depends on the strain studied, as well as on the culture media and the availability of nutrients within it. calScreener can be employed for both gram-negative and gram-positive bacteria with equal sensitivity.

Multi-center clinical validation

Symcel aims to establish calScreener™ as a new diagnostic device for antibiotic susceptibility testing with key opinion leader labs around Europe during 2018-2020.

Symcel has received one of the largest Horizon 2020 grants ever awarded to a Swedish company, €3.6 million for three clinical studies in 5 different European labs. Read more about this exciting development here and please reach out if you are interested in discovering more.

Know more about H2020 project and our clinical studies

Did you know that the MIC can increase 50-500 times more in biofilm than in planktonic growth?

Learn more about calScreener™ and biofilms

Testimonials

Picture of Christian Giske who is from Karolinska University Hospital

Ass. Prof. Christian Giske 

Chief Physician, Clinical Microbiology Department at Karolinska Hospital

Chairman, European committee on antimicrobial susceptibility testing (EUCAST)

“calScreener can be the solution to urgently needed customized treatments”

“Antimicrobial resistance is increasing rapidly and can cause infections that are extremely difficult to treat. Sometimes not even a single antimicrobial has remaining activity against these pathogens. The only possible management is customized solutions with rapid and accurate quantitative measurements. Moreover, there is a great need for testing several antimicrobials simultaneously, to predict the effects of combination therapy. Thus far there is no existing commercial solution for this problem which could be feasible to use in clinical laboratories.

The calScreener is uniquely positioned to potentially solve these problems and this is what enthused us to start testing Symcel’s technology in our research lab.”

Picture of Anni-Maria Örmälä-Odegrip who is a senior post-doc and scientific study leader at the clinical microbiology department at Karolinska Hospital

Dr. Anni-Maria Örmälä-Odegrip

Senior Postdoc and Scientific Study Leader, Clinical Microbiology Department at Karolinska Hospital

“In antimicrobial susceptibility testing we have been able to significantly cut down the time”

“The calScreener is a unique device for monitoring bacterial growth – or inhibition of growth by antimicrobials. The most valuable attribute with the technique is that by monitoring the heat released in the system, it allows you to observe the bacterial metabolism in real-time, as opposed to optical methods, where the bacterial debris or metabolically inactive cells will give a signal – often resulting in a lag in the data. 

In antimicrobial susceptibility testing we have been able to significantly cut down the time that it takes to observe if a given antimicrobial inhibits the growth of the bacteria. In bacterial growth measurements for analyzing the bacterial fitness, the unique metabolic patterns of individual species or isolates give us much more resolution on the analysis, and sometimes we have been a bit puzzled by being able to see phenomena that we would not track with other methods. But this is definitely a positive problem! 

Our next step is to start routinely using calScreener for the screening process of selecting suitable bacteriophages for phage therapy for multidrug-resistant bacteria. The characteristics of the device are perfect for observing the detailed dynamics between the bacterial hosts and their viral parasites, giving us valuable information on which phages should be selected for further trials in the development process.”

Scientific references

Antibiotic-resistant bacteria are a growing concern, and with good reason—an estimated 23,000 deaths and two million illnesses occur annually in the U.S.1 Major contributing factors are overuse, lack of regulation and scarcity of novel antibiotics.

Read more…

BACKGROUND:

Antimicrobial susceptibility testing of microorganisms is performed by either disc diffusion or broth dilution tests. In clinical use, the tests are often still performed manually although automated systems exist. Most systems, however, are based on turbidometric methods which have well-known drawbacks.

RESULTS:

In this study we evaluated isothermal micro calorimetry (IMC) for the determination of minimal inhibitory concentrations (MICs) of 12 antibiotics for five micro-organisms. Here we present the data for the 12 antibiotics and two representative microorganisms E. coli (a Gram-) and S. aureus (a Gram+). IMC was able to determine the MICs correctly according to CLSI values. Since MICs require 24 hours, time was not reduced. However, IMC provided new additional data – a continuous record of heat-producing bacterial activity (e.g. growth) in calorimetry ampoules at subinhibitory antibiotic concentrations. Key features of the heatflow (P) and aggregate heat (Q) vs. time curves were identified (t delay and Delta Q/Delta t respectively). Antibiotics with similar modes of action proved to have similar effects on t delay and/or Delta Q/Delta t.

CONCLUSION:

IMC can be a powerful tool for determining the effects of antibiotics on microorganisms in vitro. It easily provides accurate MICs – plus a potential means for analyzing and comparing the modes of action of antibiotics at subinhibitory concentrations. Also IMC is completely passive, so after evaluation, ampoule contents (media, bacteria, etc.) can be analyzed by any other method desired.

Read more…

Mycobacterium tuberculosis is a global public health concern, particularly with the emergence of drug-resistant strains. Immediate identification of drug-resistant strains is crucial to administering appropriate treatment before the bacteria are allowed to spread. However, developing countries, which are most affected by drug resistance, are struggling to combat the disease without the facilities or funds for expensive diagnostics. Recent studies have emphasized the suitability of isothermal microcalorimetry (IMC) for the rapid detection of mycobacteria. In this study, we investigate its suitability for rapid and reliable M. tuberculosis drug susceptibility testing. Specifically, IMC was used to determine the MICs of three drugs, namely, isoniazid, ethambutol, and moxifloxacin, against three mycobacteria, namely, Mycobacterium smegmatisMycobacterium avium, and Mycobacterium tuberculosis. The Richards growth model was used to calculate growth parameters, namely, the maximum bacterial growth rate and the lag phase duration from integrated heat flow-versus-time results. For example, MICs of isoniazid, ethambutol, and moxifloxacin were determined to be 1.00, 8.00, and 0.25 μg/ml, respectively. IMC, as described here, could be used not just in industrialized countries but also in developing countries because inexpensive and sensitive microcalorimeters are now available.

Read more…