Biomedical Use of Isothermal Microcalorimeters

Braissant, Olivier; Wirz, Dieter; Göpfert, Beat; Daniels, A. U.

doi:10.3390/s101009369

Cited by 75 publications

(61 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since all chemical and physical processes either consume or produce heat, IMC provides a means for continuously monitoring the rate and extent of all reactions. IMC microbiology, using the methods that we describe, entails real-time, continuous measurement of microbial metabolic heat produced in sealed ampoules containing growth medium, bacteria, and antibiotic (3,21). The use of IMC ampoules sealed in a microbiology lab prior to IMC measurements substantially augments microbiologic safety.…”

mentioning

confidence: 99%

Application of a Microcalorimetric Method for Determining Drug Susceptibility in Mycobacterium Species

et al. 2012

View full text Add to dashboard Cite

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 smegmatis, Mycobacterium 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 g/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. Drug-resistant strains of Mycobacterium tuberculosis are becoming increasingly widespread, creating a global health concern and making the treatment of tuberculosis even more difficult. Most of the cases reported in 2009 were in European countries and South Africa. However, it is likely that the occurrence of multidrug-resistant M. tuberculosis (MDR-TB), which is defined as a strain of M. tuberculosis that is resistant to both isoniazid and rifampin, is greatly underestimated in developing countries because the diagnosis is difficult and expensive (28). Direct identification of MDR-TB requires exposing an M. tuberculosis specimen to antibiotics to which it might be resistant at a series of concentrations and assessing the effects on growth-i.e., determining whether the MIC is abnormally high. In addition to M. tuberculosis, the incidence of infections caused by mycobacteria other than M. tuberculosis (MOTT) is continuously increasing, with Mycobacterium abscessus being the most pathogenic fast-growing mycobacterium (17,18,26). However, most MOTT infections have been overlooked, drug susceptibility test results are inconsistent, and some MOTT still need study to determine effective treatment (27). The determination of MICs for M. tuberculosis and MOTT by standard means is labor-intensive and/or expensive and can produce ambiguous results (11,24). Using the proportion method to determine drug susceptibility of an M. tuberculosis specimen (potentially MDR-TB) entails inoculating plates with various concentrations of each antibiotic and waiting up to 6 weeks for visible colonies to be formed. Results of tetrazolium salt assays can fluctuate depending on ...

show abstract

mentioning

confidence: 99%

Application of a Microcalorimetric Method for Determining Drug Susceptibility in Mycobacterium Species

et al. 2012

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 99%

“…It can be used to detect the presence of microorganisms rapidly by measuring microbial heat production produced by microbial growth and metabolism. [7][8][9] This technique has been applied in medicine where rapid detection of microorganisms is crucial, for example in detecting the presence of microorganism in blood transfusion products. 9 The purpose of the present prospective study was twofold: firstly, to compare microcalorimetry of sonication fluid with conventional tissue culture in detecting bacteria in orthopedic device-related infection and secondly, to evaluate the speed of microcalorimetry in the diagnosis of implant associated infection.…”

mentioning

confidence: 99%

Accurate and early diagnosis of orthopedic device‐related infection by microbial heat production and sonication

Borens

Yusuf

Steinrücken

et al. 2013

Journal Orthopaedic Research

View full text Add to dashboard Cite

Proper and rapid diagnosis of orthopedic device-related infection is important for successful treatment. Sonication has been shown to improve the diagnostic performance. We hypothesized that the combination of sonication with a novel method called microcalorimetry will further improve and accelerate the diagnosis of implant infection. We prospectively included 39 consecutive patients (mean age 59 years, 62% males) at our institution from whom 29 orthopedic prostheses and 10 osteosynthesis material were explanted. The explanted device was sonicated. The resulting sonication fluid was analyzed using microcalorimetry. Using standardized criteria to define orthopedic device-related infection, 12 cases (31%) were defined as infected. In all, positive periprosthetic tissue cultures were found. The sensitivity and specificity of microcalorimetry of sonication fluid were 100% and 97%, respectively. Mean time to detection, defined as time to reach a rising heat flow signal of 20 mW measured after equilibiration needed to get accurate measurement, was 10.9 h. In summary, microcalorimetry of sonication fluid is a reliable and a fast method in detecting the presence of microorganisms in orthopedic device-related infection. Keywords: microcalorimetry; sonication; implanted orthopedic device; infection Orthopedic implants such as joint prosthesis and fracture fixation devices are increasingly used to restore the functionality of the affected joint and the fractured bone.1,2 Unfortunately, it is estimated that 1-2% of these implants become infected.3 Orthopedic device-related infections are associated with significant morbidity and substantial health expenditures. 4 It is essential to differentiate implant-related infections from aseptic loosening because of the difference in clinical consequences. 4 However, it is difficult to make the diagnosis of implant-related infections because of variable and often subtle clinical presentation. Moreover, there are no uniform criteria for the diagnosis. 4 The diagnosis of implant related infection relies frequently on combination of clinical, imaging and histological findings, together with isolation of microorganisms from joint fluid or tissue.5 Next of being accurate, a diagnostic method for implant-related infection should be rapid in order to prompt appropriate treatment and shorten the duration of patient's morbidity.More recently, microbial cultures of samples obtained by sonication of prostheses have been shown to improve the diagnosis of prosthesic joint infection. 6 Yet, it can take up to five days before the definitive results can be released. More rapid diagnosis of implant-related infection is arguably needed in order to provide appropriate treatment.4 Isothermal microcalorimetry is a newly introduced technique in orthopedics. It can be used to detect the presence of microorganisms rapidly by measuring microbial heat production produced by microbial growth and metabolism. [7][8][9] This technique has been applied in medicine where rapid detection of microorganisms i...

show abstract

“…The sequence of peaks and troughs is characteristic of species (Said et al 2014). Conversion of the data to area under curve (cumulative heat, J) as a function of time, results in a growth curve identical in shape to that conventionally produced from optical density measurements (Braissant et al, 2011), Figure 6. The growth rate of the bacterium is reflected in the gradient of the line (higher gradient indicating faster growth).…”

Section: Discussionmentioning

confidence: 99%

“…Figure 5 shows the characteristic calorimetric output plotted as power versus time from the different probiotics, while Figure 6 represents growth curves (plotted as cumulative heat versus time, discussed below) because this provides a better correlation with conventional optical density data (Braissant et al, 2011).…”

Section: Resultsmentioning

confidence: 99%

Comparative survival of commercial probiotic formulations: tests in biorelevant gastric fluids and real-time measurements using microcalorimetry

Fredua‐Agyeman

Gaisford

2015

View full text Add to dashboard Cite

The large number of probiotic products now available makes the decision about which product to choose difficult both for the consumer and for the specialist providing dietary/nutritional advice. Data on the viability of the bacteria in these products, in the in-vivo situation, are therefore important. This study was designed to explore the comparative health and survival of probiotic species in various commercial formulations, using more realistic test systems that might allow further understanding of factors that must be controlled to give the greatest chance of delivery of live healthy bacteria to the lower gut.A total of eight commercially available probiotic preparations were selected for enumeration tests and in-vitro gastric tolerance tests. Tolerance assays were conducted in porcine gastric fluid (PGF) fed and fasted state (pH 3.4 ± 0.04), simulated gastric fluid (SGF, pH adjusted to 1.2 and 3.4) and fasted state simulated gastric fluid (FaSSGF, pH adjusted to 1.6 and 3.4). Isothermal microcalorimetry was also used to measure real-time growth of probiotics after exposure to simulated gastric fluid.Results from the enumeration tests indicated that recovery of viable organisms per dose is the same as or better than the stated label claims for liquid-based formulations but lower than the stated claim for freeze-dried products. Results from the in-vitro tolerance tests overall suggest that the PGF provided a harsher environment than the simulated systems at similar pH. In general, liquid-based products tested tended to give superior results in terms of survival compared with the freeze-dried products tested. Results from tests in the fed state in PGF suggested that food greatly affects viability. Microcalorimetric data showed that for some products probiotic species were able to grow following exposure to gastric fluid, suggesting that viable bacteria reach the gut in-vivo.

show abstract

Biomedical Use of Isothermal Microcalorimeters

Cited by 75 publications

References 62 publications

Application of a Microcalorimetric Method for Determining Drug Susceptibility in Mycobacterium Species

Application of a Microcalorimetric Method for Determining Drug Susceptibility in Mycobacterium Species

Accurate and early diagnosis of orthopedic device‐related infection by microbial heat production and sonication

Comparative survival of commercial probiotic formulations: tests in biorelevant gastric fluids and real-time measurements using microcalorimetry

Contact Info

Product

Resources

About