This work was supported by grants from the Research Foundation - Flanders (FWO Vlaanderen; G0A6113N), the Research Council of KU Leuven (C1-TRPLe; T.V. and W.E.) and the VIB (to T.V.). W.E. is a senior clinical researcher of the Research Foundation - Flanders (FWO Vlaanderen). The strain UTI89-lux was a generous gift from Prof. Seed&#39;s laboratory13.

All animal experiments were conducted in accordance with the European Union Community Council guidelines and were approved by the Animal Ethics Committee of KU Leuven (P158/2018).
1. Culturing bacteria (adapted from7,13,14)
<ol>
	<li>Preparation
	<ol>
		<li>Choose a luminescent UPEC strain that best fits the experimental needs. 
		&#8203;NOTE: Here, the clinical cystitis isolate, UTI89 (E. ...

<ol>
	<li>Foxman, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidemiology+of+urinary+tract+infections:+incidence,+morbidity,+and+economic+costs.">Epidemiology of urinary tract infections: incidence, morbidity, and economic costs.</a> American Journal of Medicine. 113 (1), 5-13 (2002).</li><li>O'Brien, V. P., Hannan, T. J., Nielsen, H. V., Hultgren, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drug+and+vaccine+development+for+the+treatment+and+prevention+of+urinary+tract+infections.">Drug and vaccine development for the treatment and prevention of urinary tract infections.</a> Microbiology Spectrum. 4 (1), 1128 (2016).</li><li>Nielubowicz, G. R., Mobley, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Host-pathogen+interactions+in+urinary+tract+infection.">Host-pathogen interactions in urinary tract infection.</a> Nature Reviews Urology. 7 (8), 430-441 (2010).</li><li>Foxman, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+epidemiology+of+urinary+tract+infection.">The epidemiology of urinary tract infection.</a> Nature Reviews Urology. 7 (12), 653-660 (2010).</li><li>Carey, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Urinary+tract+infection+of+mice+to+model+human+disease:+Practicalities,+implications+and+limitations.">Urinary tract infection of mice to model human disease: Practicalities, implications and limitations.</a> Crititical Reviews in Microbiology. 42 (5), 780-799 (2016).</li><li>Barber, A. E., Norton, J. P., Wiles, T. J., Mulvey, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strengths+and+limitations+of+model+systems+for+the+study+of+urinary+tract+infections+and+related+pathologies.">Strengths and limitations of model systems for the study of urinary tract infections and related pathologies.</a> Microbiology and Molecular Biology Reviews. 80 (2), 351-367 (2016).</li><li>Hung, C. S., Dodson, K. W., Hultgren, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+murine+model+of+urinary+tract+infection.">A murine model of urinary tract infection.</a> Nature Protocols. 4 (8), 1230-1243 (2009).</li><li>Contag, C. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photonic+detection+of+bacterial+pathogens+in+living+hosts.">Photonic detection of bacterial pathogens in living hosts.</a> Molecular Microbiology. 18 (4), 593-603 (1995).</li><li>Contag, P. R., Olomu, I. N., Stevenson, D. K., Contag, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioluminescent+indicators+in+living+mammals.">Bioluminescent indicators in living mammals.</a> Nature Medicine. 4 (2), 245-247 (1998).</li><li>Doyle, T. C., Burns, S. M., Contag, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+bioluminescence+imaging+for+integrated+studies+of+infection.">In vivo bioluminescence imaging for integrated studies of infection.</a> Cellular Microbiology. 6 (4), 303-317 (2004).</li><li>Hutchens, M., Luker, G. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applications+of+bioluminescence+imaging+to+the+study+of+infectious+diseases.">Applications of bioluminescence imaging to the study of infectious diseases.</a> Cellular Microbiology. 9 (10), 2315-2322 (2007).</li><li>Avci, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In-vivo+monitoring+of+infectious+diseases+in+living+animals+using+bioluminescence+imaging.">In-vivo monitoring of infectious diseases in living animals using bioluminescence imaging.</a> Virulence. 9 (1), 28-63 (2018).</li><li>Balsara, Z. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+susceptibility+to+urinary+tract+infection+in+the+spinal+cord-injured+host+with+neurogenic+bladder.">Enhanced susceptibility to urinary tract infection in the spinal cord-injured host with neurogenic bladder.</a> Infection and Immunity. 81 (8), 3018-3026 (2013).</li><li>Huang, Y. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+photodynamic+therapy+mediated+by+methylene+blue+and+potassium+iodide+to+treat+urinary+tract+infection+in+a+female+rat+model.">Antimicrobial photodynamic therapy mediated by methylene blue and potassium iodide to treat urinary tract infection in a female rat model.</a> Scientific Reports. 8 (1), 7257 (2018).</li><li>Mulvey, M. A., Schilling, J. D., Hultgren, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+of+a+persistent+Escherichia+coli+reservoir+during+the+acute+phase+of+a+bladder+infection.">Establishment of a persistent Escherichia coli reservoir during the acute phase of a bladder infection.</a> Infection and Immunity. 69 (7), 4572-4579 (2001).</li><li>Hannan, T. J., Hunstad, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+murine+model+for+E.+coli+urinary+tract+infection.">A murine model for E. coli urinary tract infection.</a> Methods in Molecular Biology. 1333, 83-100 (2016).</li><li>Hopkins, W. J., Gendron-Fitzpatrick, A., Balish, E., Uehling, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time+course+and+host+responses+to+Escherichia+coli+urinary+tract+infection+in+genetically+distinct+mouse+strains.">Time course and host responses to Escherichia coli urinary tract infection in genetically distinct mouse strains.</a> American Society for Microbiology. 66 (6), 2798 (1998).</li><li>Zhang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+of+Nonsteroidal+Anti-inflammatory+Drugs+for+Treatment+of+Uncomplicated+Lower+Urinary+Tract+Infections+in+Women:+A+Meta-analysis.">Efficacy of Nonsteroidal Anti-inflammatory Drugs for Treatment of Uncomplicated Lower Urinary Tract Infections in Women: A Meta-analysis.</a> Infectious Microbes &amp; Diseases. 2 (2), 77-82 (2020).</li><li>Vanherp, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensitive+bioluminescence+imaging+of+fungal+dissemination+to+the+brain+in+mouse+models+of+cryptococcosis.">Sensitive bioluminescence imaging of fungal dissemination to the brain in mouse models of cryptococcosis.</a> Disease Models &amp; Mechanisms. 12 (6), 039123 (2019).</li><li>Keyaerts, M., Caveliers, V., Lahoutte, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioluminescence+imaging:+looking+beyond+the+light.">Bioluminescence imaging: looking beyond the light.</a> Trends in Molecular Medicine. 18 (3), 164-172 (2012).</li><li>Marques, C. N., Salisbury, V. C., Greenman, J., Bowker, K. E., Nelson, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discrepancy+between+viable+counts+and+light+output+as+viability+measurements,+following+ciprofloxacin+challenge+of+self-bioluminescent+Pseudomonas+aeruginosa+biofilms.">Discrepancy between viable counts and light output as viability measurements, following ciprofloxacin challenge of self-bioluminescent Pseudomonas aeruginosa biofilms.</a> Journal of Antimicrobial Chemotherapy. 56 (4), 665-671 (2005).</li><li>Vande Velde, G., Kucharikova, S., Van Dijck, P., Himmelreich, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioluminescence+imaging+increases+in+vivo+screening+efficiency+for+antifungal+activity+against+device-associated+Candida+albicans+biofilms.">Bioluminescence imaging increases in vivo screening efficiency for antifungal activity against device-associated Candida albicans biofilms.</a> International Journal of Antimicrobial Agents. 52 (1), 42-51 (2018).</li><li>Oliver, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+findings+on+the+viable+but+nonculturable+state+in+pathogenic+bacteria.">Recent findings on the viable but nonculturable state in pathogenic bacteria.</a> FEMS Microbiology Reviews. 34 (4), 415-425 (2010).</li><li>Kucharikova, S., Van de Velde, G., Himmelreich, U., Van Dijck, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Candida+albicans+biofilm+development+on+medically-relevant+foreign+bodies+in+a+mouse+subcutaneous+model+followed+by+bioluminescence+imaging.">Candida albicans biofilm development on medically-relevant foreign bodies in a mouse subcutaneous model followed by bioluminescence imaging.</a> Journal of Visualized Experiments: JoVE. (95), e52239 (2015).</li><li>Van de Velde, G., Kucharikova, S., Schrevens, S., Himmelreich, U., Van Dijck, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+non-invasive+monitoring+of+pathogen-host+interactions+during+Candida+albicans+biofilm+formation+using+in+vivo+bioluminescence.">Towards non-invasive monitoring of pathogen-host interactions during Candida albicans biofilm formation using in vivo bioluminescence.</a> Cellular Microbiology. 16 (1), 115-130 (2014).</li></ol>

The authors declare no conflicts of interest.

Advantages of BLI compared to CFU counts 
Longitudinal data 
A major disadvantage of the traditional method of counting CFU to quantify microbial burden is the requirement of post-mortem organ homogenates, providing only one cross-sectional data point per animal. Conversely, BLI enables non-invasive longitudinal follow-up of infected animals. The animals can be imaged 2 to 3 times a day, providing detailed insight into the kinetics of the infection. Additionally, repeated measures of t...

Urinary tract infections (UTI) are among the most common bacterial infections in humans. Almost half of all women will experience a symptomatic UTI during their lifetime1. Infections limited to the bladder can give rise to urinary symptoms such as increase in urinary frequency, urgency, hematuria, incontinence, and pain. When the infection ascends to the upper urinary tract, patients develop pyelonephritis, with malaise, fever, chills, and back pain. Furthermore, up to 20% of patients with UTI suffer from recurrent infections resulting in a dramatic decrease in antibiotic sensitivity2,3,4. In recent years, there has been a growing interest in novel therapies for the treatment and prevention of recurrent UTI. Despite a better understanding of the innate and adaptive immunity of the lower urinary tract and of the bacterial virulence factors necessary for invasion and colonization, no radical changes in the treatment regime have been translated to the daily urological practice2. In order to study UTI pathogenesis and susceptibility in vivo, a reproducible and non-invasive assay is indispensable.
Multiple animal UTI models have been described ranging from nematodes to primates, but the murine model is predominantly used5,6. This model consists of transurethral catheterization of (female) mice and subsequent instillation of a bacterial suspension, most commonly uropathogenic Escherichia coli (UPEC), directly into the bladder lumen7. After inoculation, the bacterial load has traditionally been quantified by determining colony forming units (CFU). This technique requires sacrificing animals to obtain post-mortem organ homogenates and serial dilutions, limiting data output and reproducibility. Moreover, longitudinal follow-up of the bacterial load in individual animals is not possible using this technique.
In 1995, Contag et al. suggested the use of bioluminescent-tagged pathogens to monitor disease processes in living animals8,9. Since then, bioluminescence imaging (BLI) has been applied to numerous infection models such as meningitis, endocarditis, osteomyelitis, skin, and soft tissue infections, etc.10,11,12. In the murine UTI model, a UPEC strain with the complete lux operon (luxCDABE) from Photorhabdus luminescens can be used13. An enzymatic reaction is catalyzed by the bacterial luciferase which is dependent on the oxidation of long-chain aldehydes reacting with reduced flavin mononucleotide in the presence of oxygen, yielding the oxidized flavin, a long-chain fatty acid and light12. The lux operon encodes for the luciferase and other enzymes required for the synthesis of the substrates. Therefore, all metabolically active bacteria will continuously emit blue green (490 nm) light without the need for the injection of an exogenous substrate12. Photons emitted by lux-tagged bacteria can be captured using highly sensitive, cooled charge-coupled device (CCD) cameras.
The use of bioluminescent bacteria in a model for UTI allows for the longitudinal, non-invasive quantification of the bacterial load, omitting the need for sacrificing animals at fixed time points during the follow-up for CFU determination. Despite the wide range of possibilities, accumulating evidence for the robustness of this BLI technique in other fields and its advantages over classic models of UTI, it has not been widely implemented in the UTI research. The protocol presented here provides a detailed step-by-step guide and highlights the advantages of BLI for all future UTI research.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>96-well Black Flat Bottom Polystyrene Plate</td>
			<td>Corning</td>
			<td>3925</td>
			<td>for in vitro imaging</td>
		</tr>
		<tr>
			<td>Aesculap ISIS</td>
			<td>Aesculap</td>
			<td>GT421</td>
			<td>hair trimmer, with GT608 cap</td>
		</tr>
		<tr>
			<td>Anesthesia vaporizer</td>
			<td>Harvard apparatus limited</td>
			<td>N/A</td>
			<td>https://www.harvardapparatus.com/harvard-apparatus-anesthetic-vaporizers.html</td>
		</tr>
		<tr>
			<td>Baytril 100 mg/mL</td>
			<td>Bayer</td>
			<td>N/A</td>
			<td>Enrofloxacin</td>
		</tr>
		<tr>
			<td>BD Insyte Autoguard 24 GA</td>
			<td>BD</td>
			<td>382912</td>
			<td>Yellow angiocatheter, use sterile plastic tip for instillation</td>
		</tr>
		<tr>
			<td>C57Bl/6J mice</td>
			<td>Janvier</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge 5804R</td>
			<td>Eppendorf</td>
			<td>EP022628146</td>
			<td></td>
		</tr>
		<tr>
			<td>Dropsense 16</td>
			<td>Unchained Labs</td>
			<td>Trinean</td>
			<td>to measure OD 600nm</td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Phosphate Buffered Saline, Gibco</td>
			<td>ThermoFisher Scientific</td>
			<td>REF 14040-083</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol 70% denaturated 5L</td>
			<td>VWR international</td>
			<td>85825360</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon 14ml Round Bottom Polystyrene Tube, Snap-Cap</td>
			<td>Corning</td>
			<td>352057</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon 50ml cellstart</td>
			<td>Greiner</td>
			<td>227285</td>
			<td></td>
		</tr>
		<tr>
			<td>Hamilton GASTIGHT syringe, PTFE luer lock, 100 &#181;L</td>
			<td>Sigma-Aldrich</td>
			<td>26203</td>
			<td>to ensure slow bacterial instillation of 50 &#181;L</td>
		</tr>
		<tr>
			<td>Inoculation loop</td>
			<td>Roth</td>
			<td>6174.1</td>
			<td>holder: Art. No. 6189.1</td>
		</tr>
		<tr>
			<td>Iso-Vet 1000mg/g</td>
			<td>Dechra Veterinary products</td>
			<td>N/A</td>
			<td>Isoflurane</td>
		</tr>
		<tr>
			<td>IVIS Spectrum In Vivo Imaging System</td>
			<td>PerkinElmer</td>
			<td>REF 124262</td>
			<td>imaging device</td>
		</tr>
		<tr>
			<td>Kanamycine solution 50 mg/mL</td>
			<td>Sigma-Aldrich</td>
			<td>CAS 25389-94-0</td>
			<td></td>
		</tr>
		<tr>
			<td>Living Imaging Software</td>
			<td>PerkinElmer</td>
			<td>N/A</td>
			<td>BLI acquisition software, version 4.7.3</td>
		</tr>
		<tr>
			<td>Luria Bertani Broth</td>
			<td>Sigma-Aldrich</td>
			<td>REF L3022</td>
			<td>alternatively can be made</td>
		</tr>
		<tr>
			<td>Luria Bertani Broth with agar</td>
			<td>Sigma-Aldrich</td>
			<td>REF L2897</td>
			<td>alternatively can be made</td>
		</tr>
		<tr>
			<td>Petri dish Sterilin 90mm</td>
			<td>ThermoFisher Scientific</td>
			<td>101VR20</td>
			<td>to fill with LB agar supplemented with Km</td>
		</tr>
		<tr>
			<td>Pyrex Culture flask 250 mL</td>
			<td>Sigma-Aldrich</td>
			<td>SLW1141/08-20EA</td>
			<td></td>
		</tr>
		<tr>
			<td>Slide 200 Trinean</td>
			<td>Unchained Labs</td>
			<td>701-2007</td>
			<td>to measure OD 600nm</td>
		</tr>
		<tr>
			<td>UTI89-lux</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Generous gift from Prof. Seed</td>
		</tr>
		<tr>
			<td>Vortex</td>
			<td>VWR international</td>
			<td>444-1372</td>
			<td></td>
		</tr>
	</tbody>
</table>

longitudinal follow-up of urinary tract infections and their treatment in mice using bioluminescence imaging

Urinary tract infections (UTI) rank among the most common bacterial infections in humans and are routinely treated with empirical antibiotics. However, due to increasing microbial resistance, the efficacy of the most used antibiotics has declined. To find alternative treatment options, there is a great need for a better understanding of the UTI pathogenesis and the mechanisms that determine UTI susceptibility. In order to investigate this in an animal model, a reproducible, non-invasive assay to study the course of UTI is indispensable.
For years, the gold standard for the enumeration of bacterial load has been the determination of Colony Forming Units (CFU) for a particular sample volume. This technique requires post-mortem organ homogenates and serial dilutions, limiting data output and reproducibility. As an alternative, bioluminescence imaging (BLI) is gaining popularity to determine the bacterial load. Labeling pathogens with a lux operon allow for the sensitive detection and quantification in a non-invasive manner, thereby enabling longitudinal follow-up. So far, the adoption of BLI in UTI research remains limited.
This manuscript describes the practical implementation of BLI in a mouse urinary tract infection model. Here, a step-by-step guide for culturing bacteria, intravesical instillation and imaging is provided. The in vivo correlation with CFU is examined and a proof-of-concept is provided by comparing the bacterial load of untreated infected animals with antibiotic-treated animals. Furthermore, the advantages, limitations, and considerations specific to the implementation of BLI in an in vivo UTI model are discussed. The implementation of BLI in the UTI research field will greatly facilitate research on the pathogenesis of UTI and the discovery of new ways to prevent and treat UTI.

In vivo BLI correlates with CFU of the inoculum at time of instillation. 
To evaluate the detection limit of BLI in vivo and the correlation with CFU of the inoculum, mice were infected with different concentrations of UTI89-lux and PBS as a negative control. Before instillation, uninfected animals were scanned to determine the background luminescence. Subsequent images were obtained immediately post-instillation (Figure 1A). ...

Watch this Scientific Journal Video about Longitudinal Follow-Up of Urinary Tract Infections and Their Treatment in Mice using Bioluminescence Imaging at JoVE.com

Longitudinal Follow-Up of Urinary Tract Infections and Their Treatment in Mice using Bioluminescence Imaging

This manuscript describes the intravesical administration of uropathogenic bacteria with a lux operon to induce a urinary tract infection in mice and subsequent longitudinal in vivo analysis of the bacterial load using bioluminescence imaging.

Urinary tract infections (UTI) rank among the most common bacterial infections in humans and are routinely treated with empirical antibiotics. However, ...

The enumeration of colony forming units was limiting the reproducibility of research in the UTI field. Bioluminescence imaging will advance in vivo UTI research on bladder physiology, UTI pathogenesis and susceptibility. Bioluminescence imaging enables longitudinal follow up with real-time insight into the evolution of the infection.Moreover, it drastically reduces the number of animals needed. Bioluminescence imaging facilitates research on recurrent or chronic infections, which are frequent in humans. Additionally, researchers can identify ascending infections or dissemination to the blood using bioluminescence imaging.Obtain single colonies by streaking out the glycerol stock of bacteria with an inoculation loop on LB plates supplemented with kanamycin sulfate, and culturing overnight at 37 degrees Celsius. Fill a sterile 14 milliliter polystyrene round bottom tube, with dual-position snap caps with five milliliters of LB broth supplemented with kanamycin sulfate. Pick a single bacterial colony with an inoculation loop, and add this to the LB broth.Vortex for 10 seconds to ensure proper mixing. Culture statically with the snap cap in the open position at 37 degrees Celsius overnight. After the incubation, vortex the tube for 10 seconds to ensure proper homogenization of the bacterial culture.Make a subculture in the Erlenmeyer by adding 25 microliters of the bacterial suspension to 25 milliliters of fresh LB medium without antibiotics. Close the Erlenmeyer and culture statically overnight. On the day of installation, pour the culture from the Erlennmeyer into a 50 milliliter culture tube, and centrifuge.Decant the supernatant and resuspend the bacterial pellet in 10 milliliters of sterile PBS. Vortex the tube again for 10 seconds. Choose the experimental concentration of the inoculum and determine the corresponding OD at 600 nanometers using the standard curve.Addd one milliliter of the resuspended bacterial culture into nine milliliters of sterile PBS and adjust until the desired OD 600 nanometer is reached. Mount a sterile 24-gauge angiocatheter tip on a 100-microliter syringe. Fill the syringe with the prepared bacterial solution.Place one animal on a working surface in the supine position and maintain a stable isoflurane anesthesia using a nose cone during the installation. Apply the eye ointment. Expel the residual urine by applying gentle compression and making circular movements on the suprapubic region, then clean the lower abdomen with 70%ethanol.Lubricate the catheter tip with normal saline. Put the index finger on the non-dominant hand on the abdomen and push it gently upwards. Start the catheterization of the urethra vertically in a 90-degree angle.Once resistance is encountered, tilt it horizontally before inserting it further. Perform a slow installation of 50 microliters of the bacterial inoculum. After the installation, keep the syringe and catheter in place for a few more seconds and then slowly retract to prevent leakage.Use one catheter per experimental group. Position the animal in a supine position in the nose cone to prepare it for imaging, and prepare it for imaging using one catheter per experimental group. If necessary, administer antibiotics or experimental drugs, as mentioned in the text manuscript.Open the BLI acquisition software and click on Initialize in the imaging device to test the camera and stage controller system and to cool the charge-coupled device camera to minus 90 degrees Celsius. Click on Acquisition, AutoSave To.Select Luminescence and Photograph. Check the default luminescent settings by setting the excitation filter to Block and emission filter to Open.Set the exposure time to auto when taking the first image. For in vivo measurements and bright signals, set the exposure time to around 30 seconds. Reduce the exposure time if a warning appears due to a saturated image.Select the medium binning, F/stop one, and choose the correct FOV. Set the subject height to one centimeter when imaging mice. Image up to five miles simultaneously and separate the animals using the light baffle to prevent reflection.Close the door and click on Acquire to start the imaging sequence, then fill in detailed information about the experiment. Remove mice from the imaging chamber and return them to their cage. Check for full recovery after anesthesia, then return the cages to the ventilated racks until the next imaging cycle.Start the imaging software and load the experimental file by clicking on Browse. Use the tool palette to adjust the color scale of the image. Use the ROI tools to draw a region of interest on the image, ensuring that it is large enough to cover the complete area and using the same dimensions for all the images.Then click on ROI measurement to quantify the light intensity. Subsequent images of mice obtained immediately post-installation showed that was robustly detectable above 20, 000 colony forming units, and a linear correlation between the colony forming units of the inoculum and the bioluminescence in vivo was established. The natural evolution of a urinary tract infection was studied in a control group that did not receive any treatment.The effect of antibiotic treatment on the infection kinetics was visualized in detail in a group of antibiotic-treated animals. An immediate decrease in bacterial load, as measured by total photon flux, was seen after the first dose of Enrofloxacin. None of the treated animals had a subsequent rise in bacterial load.The overall bacterial load of each animal was calculated using the area under the curve of the log transformed total photon flux, showing a significant difference between animals treated with Enrofloxacin and untreated animals over the time course of 10 days. These results provide proof of concept that BLI can be used to evaluate differences in UTI infection kinetics. Bioluminescence imaging is a noninvasive technique that can be combined with other methods such as regular collection of urinary samples for bacterial or biochemical analysis or for the experiments.Here we have demonstrated that bioluminescence imaging is a powerful tool to evaluate novel therapeutic strategies on the disease course of urinary tract infections.

longitudinal-follow-up-urinary-tract-infections-their-treatment-mice

Research

JoVE Journal

Immunology and Infection

2.8K vues.  KU Leuven. Le dénombrement des unités formant des colonies limitait la reproductibilité de la recherche dans le domaine des infections urinaires. L’imagerie par bioluminescence fera progresser la recherche in vivo sur les infections urinaires sur la physiologie de la vessie, la pathogenèse des infections urinaires et la susceptibilité. L’imagerie par bioluminescence permet un suivi longitudinal avec un aperçu en temps réel de l’évolution de l’infection.De plus, il réduit considé...