We thank Dr Matthieu Rousseau for critical reading of the manuscript and the Laboratory of Dendritic Immunobiology for their helpful insights during the development of this protocol and project. This work was supported in part by funding from the European Union Seventh Framework Programme Marie Curie Action (PCIG11-GA- 2012-3221170, and the Immuno-Oncology LabEx (MAI).

Mouse experiments were conducted in accordance with approval of protocol number 2012-0024 by the Comit&#233; d&#39;&#233;thique en exp&#233;rimentation animale Paris Centre et Sud (the ethics committee for animal experimentation), in application of the European Directive 2010/63 EU.
1. Preparation of Catheters
<ol>
	<li>Prepare one pediatric intravenous-access cannula for each group of mice to be infected. Using the inbuilt spring mechanism, divest each cannula of its needle, as instructed by the manufacturer. Discard the needles, preserving only the plastic intravenous cannula.</li>
	<li>Sterilize catheters in a laminar flow hood for one ultraviolet (U.V.) cycle, typically 25 - 30 min. 
	Note: Catheters can be used for more than one mouse, however a new catheter should be used between experimental groups, sexes, or bacterial strains.</li>
</ol>
2. Preparation of Uropathogenic E. coli for Infection
<ol>
	<li>At least two days prior to infection, using a sterile inoculation loop, streak UPEC from a frozen bacterial stock onto a Luria Broth (LB) agar plate, containing antibiotics if appropriate. Incubate at 37 &#176;C overnight. Plates can be stored at 4 &#176;C for up to one week.</li>
	<li>In a 100 ml sterile Erlenmeyer flask, inoculate 10 ml LB, containing antibiotics if appropriate, with a single colony from the LB plate and incubate standing at 37 &#176;C overnight (approximately 16 - 18 hr). 
	Note: Standing cultures permit the expression of type 1 pili, which are necessary for infection23. Cultures grown shaking will have less efficient pili expression, and therefore, inconsistent rates of infection.</li>
	<li>Measure the optical density (OD)600 of the overnight culture and calculate the number of bacteria per ml using a pre-determined growth curve. As an example, for UPEC strain UTI89, OD600 = 0.35 is equivalent to 2 x 108 CFU per ml, thus, an overnight culture with an OD600 = 2.4 would be equivalent to 13.7 x 108 CFU per ml. Empirically determine the relationship between the OD600 and viable bacteria with every new strain employed for infection.</li>
	<li>Determine the amount of bacteria needed by considering the number of animals to be infected and that each mouse should receive approximately 107 colony-forming units (CFU) in 50 &#956;l PBS. Include in the calculation the ~130 &#181;l dead volume of the catheter and syringe nub and 100 &#181;l needed to determine the inoculum.
	<ol>
		<li>Spin the bacterial suspension in a tabletop microcentrifuge at 17,000 x g for 1 min and resuspend the resulting bacterial pellet at 2 x 108 CFU per ml in PBS. Serially dilute an aliquot of this suspension and plate on LB agar, with antibiotics if appropriate, to determine the exact inoculum for each infection.</li>
	</ol>
	</li>
	<li>Draw the bacterial inoculum into a 1 ml syringe and attach the catheter to the end of the syringe. Tap the syringe to remove any air and depress the plunger to fill the dead air space in the catheter before beginning the instillation.</li>
</ol>
3. Preparation of Mice
<ol>
	<li>Anesthetize mice via intraperitoneal injection of 100 mg/kg ketamine and 5 mg/kg xylazine. Supplemental heat can be provided.&#160;</li>
	<li>Ensure that each mouse is fully sedated by squeezing the footpad with medium pressure. Mice are fully sedated when they do not react and require 3 - 5 min to reach this state.</li>
	<li>Place mice supine and apply medium pressure to the lower abdomen to empty the bladder of urine. Full bladders feel like a pea under the skin between the ileac crests. 
	Note: Inhaled isoflurane has been used to catheterize female mice15,22, however, it has not been tested whether male mice are sufficiently anesthetized by inhaled isoflurane for this procedure.</li>
</ol>
4. Transurethral Instillation of Female Mice
<ol>
	<li>Using the non-dominant hand, place the thumb on the tail and a finger of the same hand on the abdomen of the mouse and apply gentle pressure in opposing directions to hold the mouse firmly in place.</li>
	<li>Place the tip of the catheter perpendicular to the mouse at the urethral orifice. With gentle pressure, slide the catheter into the urethra, until the hub meets the urethral orifice, while simultaneously lowering the syringe so that it is parallel to the working surface. The catheter requires no lubrication. Do not push or force the catheter into the urethra. The catheter should slide smoothly and easily into the urethra, with little to no resistance.
	<ol>
		<li>Before instilling the inoculum (step 4.3), once the catheter is in place, very gently pull the abdominal skin towards the head of the mouse with the finger from the non-dominant hand that is already on the abdomen of the mouse (step 4.1). If the catheter is in the urethra, the tissue composing the urethra orifice will not move, whereas if the catheter is incorrectly placed in the vagina, the tissue will move up and away from the catheter. This rapid test should be performed on each mouse.</li>
	</ol>
	</li>
	<li>When the hub of the catheter meets the urethral orifice, slowly dispense 50 &#181;l of the bacterial inoculum. A slow instillation rate minimizes vesicoureteral reflux into the kidney. Slowly remove the catheter to prevent leakage, over a count of 5. Place mice in their cages in a supine position.</li>
</ol>
5. Transurethral Instillation of Male Mice
<ol>
	<li>Place two thumb forceps cranially and caudally to the mouse&#39;s external genitalia. Retract the prepuce to fully expose the glans penis. Once the penis is externally positioned, release the thumb forceps.</li>
	<li>Reposition the forceps to stabilize the protruding penis perpendicular to the animal, holding the organ gently but tautly. Visualize the urethral meatus and carefully introduce the catheter into the small opening at the tip of the organ. Gently guide the catheter into the penis, toward the body of the mouse, maintaining gentle tension with the forceps. The catheter requires no lubrication. Do not force the catheter into the penis; the catheter should slide smoothly into the urethra, indicating correct placement.</li>
	<li>Once the hub of the catheter meets the tip of the penis, very slowly dispense 50 &#181;l of the inoculum, while maintaining the position of the penis. The quality of the instillation can be noted at this time according to a predetermined instillation quality score, such as that shown in Figure 2.</li>
	<li>Retract the catheter slowly, over a count of 5, to prevent leakage of the inoculum. Place mice in their cages in a supine position. Animals should begin to recover 30 - 45 min following administration of the anesthetic.</li>
</ol>
6. Determination of CFU in Infected Organs
<ol>
	<li>At predetermined time-points, sacrifice mice using approved standard operating procedures (e.g., cervical dislocation or carbon dioxide overdose). Moisten the abdomen thoroughly with 70% ethanol to minimize contamination by fur.</li>
	<li>Make an incision across the lower third of the mouse&#39;s abdomen of at least 2 cm using scissors and aseptically remove the bladder and any other desired organs, including but not limited to, kidneys, testis, seminal vesicles, or preputial glands, into 5 ml polypropylene snap cap tubes containing 1 ml sterile PBS. Keep all samples on ice.</li>
	<li>Homogenize the organs with a handheld homogenizer until almost no solid tissue remains, approximately 15 - 60 sec depending on the organ. Fat does not homogenize well, and is easily recognizable as shiny beige-white tissue. Discard fat prior to or following homogenization. Wash the homogenizer in ethanol followed by PBS between each experimental or organ group. 
	Note: Typically, use handheld homogenizers or bead mill homogenizers. While all of these systems have yielded similar results, as determined by direct comparison of bacterial CFU at 24 hr post-infection, the optimal conditions to homogenize host tissue while preserving bacterial viability should be determined empirically before performing this protocol routinely.</li>
	<li>Perform serial dilutions of homogenized organ suspensions. Plate dilutions on LB agar plates, containing antibiotics when appropriate, and incubate overnight (~15 hr) at 37 &#176;C. UPEC strains have very rapid doubling times and as such, care should be taken to not incubate the agar plates too long because this will hinder the ability to count individual colonies.</li>
</ol>
7. Flow Cytometric Analysis of Bladder Tissue
<ol>
	<li>Prepare digestion buffer containing collagenase at 34 units/mL and DNase at 100 &#181;g/mL, in PBS. Keep on ice. Prepare one 15 ml conical tube per animal to be analyzed and aliquot 1 ml digestion buffer per tube.</li>
	<li>At predetermined timepoints, sacrifice mice using approved standard operating procedures (e.g., cervical dislocation or carbon dioxide overdose). Moisten the abdomen thoroughly with 70% ethanol to minimize contamination by fur.</li>
	<li>Make an incision across the lower third of the mouse&#39;s abdomen of at least 2 cm using scissors and remove the entire bladder. Mince well with scissors, cutting the bladder into 2 - 3 mm2 sized pieces, typically about 8 pieces.
	<ol>
		<li>Add one minced bladder per tube containing digestion buffer. Shake to wash minced bladder tissue into the digestion buffer. Keep on ice until all bladders are dissected and minced.</li>
	</ol>
	</li>
	<li>Incubate minced bladders for 60 - 75 min at 37 &#176;C, with vigorous shaking by hand for 5 s every 15 min. When the tissue has a glassy transparent appearance, resembling wet tissue paper, digestion is complete. Prolonged digestion will remove surface proteins from the cells needed for identification and should be avoided.</li>
	<li>Inactivate the digestion enzymes by adding 2 - 3 mL of ice-cold flow cytometry buffer (PBS containing 2% fetal bovine serum (FBS) and 0.2 mM EDTA) and mix gently. Place tubes on ice.</li>
	<li>To ensure a single cell suspension and to remove any connective tissue, pass the contents of the tube through a 100 &#181;m filter placed in a 15 mL conical tube. Gently press any remaining tissue through the filter with the end of a syringe plunger. Wash the filter with an additional 2 mL flow cytometry buffer. Keep samples on ice.</li>
	<li>Wash samples by centrifugation for 7 min at 200 x g, 4 &#176;C. Resuspend pellets in 100 &#181;L flow cytometry buffer containing Fc block, diluted to 5 &#181;g/mL and transfer to a 96-well round bottom plate. After 10 - 15 min, add 100 &#181;L desired antibody cocktail to each sample. Incubate samples for 30 - 45 min, on ice, protected from light. 
	Note: Fc block is a reagent used to prevent the binding of the Fc portion of antibodies to cells expressing Fc receptors. Its purpose is to minimize nonspecific antibody binding. Determination of antibodies to use will be dependent upon the hypothesis being tested in the experiment and should be selected with input from the literature. In Figure 3, to measure the overall immune cell infiltration, an anti-CD45 antibody was employed, which is a pan-immune cell protein.</li>
	<li>Wash samples by centrifugation for 7 min at 200 x g, 4 &#176;C. Resuspend cell pellets in 200 &#181;L flow cytometry buffer and pass samples through a 40 &#181;m cell strainer on a 5 ml polystyrene tube just prior to acquisition on a flow cytometer.</li>
	<li>Collect the entire sample on the flow cytometer. A good digestion will yield 200,000 - 400,000 cells, with 8,000 - 10,000 CD45+ immune cells from na&#239;ve mouse bladders, while infected organs will contain more cells16 (Figure 3). 
	Note: Samples prepared for flow cytometric analysis cannot be used to evaluate CFU. It is not recommended to split the bladder into two parts as no evidence exists to demonstrate that UPEC colonization or immune cell infiltration is uniform throughout the tissue.</li>
</ol>

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The authors have nothing to disclose.

Transurethral instillation of male mice offers many new research opportunities into the influence of sex on bladder mucosal disease, but also presents several challenges. Foremost, one limitation is that the instillation may initially prove to be technically difficult, resulting in excessive inflammation during catheter insertion. Improvement in technique can be achieved by the instillation of dead mice with a colored solution, such as Evans blue dye. To confirm that the instillation is successful, bladders should be visually inspected and the volume of instilled liquid can be evaluated by extraction with a tuberculin syringe. The importance of slow, gentle movements cannot be overstated: there should be no resistance and no force used to insert the catheter, as this will result in excess inflammation and tissue damage. When performed correctly, the catheter will slide effortlessly into the urethra. If resistance or obstruction is felt, it is best to remove the catheter and reattempt insertion.
By correlating the quality of the instillation to bacterial burden 24 hr post-infection, we demonstrated that an imperfect technique, in which a small amount of the bacterial inoculum is lost at the time of infection, still results in robust colonization of the bladder. In utilizing this protocol, an investigator should aim to achieve leak-free instillations. However, the robustness of the procedure ensures that imperfect instillations will still provide useful data and interpretable results.
The great advantage of our technique over the only published alternative method of male bladder infection is its non-invasive, non-surgical approach. Our approach using transurethral instillation follows the physiological route through the urethra to the bladder, without disrupting the structural integrity of the abdomen. The invasive technique, described by Olson and colleagues20, includes factors inherent to surgical procedures, including inflammation, delayed healing, and resultant scar tissue. Especially relevant with regard to studies of immune response to infection is the organism&#39;s response to surgical trauma. This includes the formation of a pro-inflammatory milieu and potential tissue granulation, as well as an anti-inflammatory wound healing program as part of the healing process. These factors represent undesirable influences within the experimental setting.
Finally, the objective of this study was to develop a method that allows direct comparison of male and female immune responses during the course of UTI, which can be applied to future studies addressing the influence of sex on bladder mucosal disease, such as infection and cancer biology. As a second distinct advantage, the method described here mirrors that used in female mice for decades19. Thus, experiments performed in male mice with this technique are comparable to a wide body of existing research. Our experiments have revealed that differences in response do exist and that these differences may provide clues to understanding sex-based disparities in response to mucosal infections, as well as other diseases of the bladder.

Urinary tract infections (UTI) are one of the most common infections in developed countries1. Infection rates are similar between females and males among neonates and the elderly2. Premenopausal adult women, however, have a greatly increased incidence of community-acquired UTI compared to men2,3. Given that this disease primarily impacts women, fundamental and clinical research has overwhelmingly focused on UTI in females. However, UTI in men is a significant and understudied health care challenge4. Indeed, because UTI in men are associated with higher morbidity, these infections are routinely defined as complicated4,5.
As our understanding of the central role of sex biases in physiology and pathology evolves, new methods are required to explore this previously neglected aspect of disease. Sex differences play an essential role in immunity and infection; females have higher incidence of autoimmune disease, while males are more susceptible to certain infections, such as tuberculosis, malaria, and HIV6,7. Bladder cancer, another urologic pathology, is significantly more prevalent in men than in women, and several studies have shown a role for androgens in the development of malignancy8,9,10,11,12. Notably, however, investigation of intravesical therapies for bladder cancer is performed exclusively in female animals, due to the inability to repeatedly catheterize male mice13.
The study of UTI pathogenesis relies heavily on rodent models of infection (e.g., mice and rats). Murine models of UTI may employ uropathogens originally isolated from human infections, such as uropathogenic E. coli (UPEC), Klebsiella, Enterococcus, Staphylococcus, or Proteus14. Typically, bacteria are introduced into the bladder via catheterization of the urethra. Following infection, bladders and kidneys can be removed to assess specific parameters of infection, such as bacterial colonization, tissue damage, or host immune response15,16. Universally, however, only female animals are used for UTI research. Indeed, many studies have noted that, due to anatomical reasons, catheterization of male mice is not possible13,17,18,19. More recently, a surgical approach to male instillation has been described, in which the abdomen is opened, the bladder is externally displaced by applying gentle pressure to the opening in the abdomen, and bacteria are injected into the bladder20. This approach enables male infection, at the cost of surgical intervention. Thus, a major caveat of this approach includes the influence of inflammation, on the outcome of infection such as the potential to induce an anti-inflammatory wound-healing response to the incision21. As our interests include understanding sex bias in response to disease, we developed a method of bacterial intravesical instillation in male mice that more closely matches the long-established non-surgical transurethral approach used in female rodents22.
Our model builds upon an established methodology and provides the ability to directly compare the host immune response to UTI in female and male animals. This method will permit dissection of sex-based differences in infection, and potentially offer molecular and cellular clues to the pronounced differences in susceptibility and response to infection between the sexes. Additionally, this model has value beyond UTI studies, allowing the establishment of models to investigate other bladder-associated diseases, such as bladder cancer, prostatitis, under- or over-active bladder syndrome, and interstitial cystitis.

<table><tbody><tr><td>BD Insyte Autoguard Shielded IV Catheters 24 G, 0.7 mm external diameter, 14 mM long</td><td>BD Medical</td><td>381811 or 381411*</td><td>* catalog number is country-dependent</td></tr><tr><td>inoculating loop</td><td>Greiner Bio-One</td><td>731171</td><td></td></tr><tr><td>LB Miller broth</td><td>Difco</td><td>244620</td><td></td></tr><tr><td>LB Miller agar</td><td>Difco</td><td>244520</td><td></td></tr><tr><td>Cuvettes</td><td>Bio-rad</td><td>223-9955</td><td></td></tr><tr><td>syringes</td><td>B Braun</td><td>9166017V</td><td></td></tr><tr><td>Thumb (Adson) forceps</td><td>Fine Science Tools</td><td>11006-12</td><td></td></tr><tr><td>5 ml tubes, polypropylene</td><td>Falcon</td><td>352063</td><td></td></tr><tr><td>Tissue Ruptor disposable probes</td><td>Qiagen</td><td>990890</td><td></td></tr><tr><td>15 ml flip cap tubes</td><td>Thermo Scientific</td><td>362694</td><td></td></tr><tr><td>DNAse</td><td>Invitrogen</td><td>18047019</td><td></td></tr><tr><td>Liberase TM</td><td>Sigma-Aldrich</td><td>5401119001</td><td>should be aliquotted and stored at -20 &amp;deg;C to avoid repeated freeze-thaw</td></tr><tr><td>100 &amp;micro;M MACS SmartStrainers&amp;nbsp;</td><td>Miltenyi</td><td>130-098-463</td><td>compatible with 15 ml tubes, preferred</td></tr><tr><td>100 &amp;micro;m cell strainers&amp;nbsp;</td><td>Falcon</td><td>352360</td><td>compatible with 50 ml tubes, if MACS Smart Strainers are not available</td></tr><tr><td>96 well plate</td><td>Falcon</td><td>353077</td><td></td></tr><tr><td>Fc block</td><td>BD Pharmingen</td><td>553142</td><td>anti-CD16/CD32</td></tr><tr><td>anti-mouse CD45 antibody</td><td>BD Biosciences</td><td>561487</td><td>many different fluorescent conjugation options are available</td></tr><tr><td>5 ml tubes polystyrene with filter cap</td><td>Falcon</td><td>352235</td><td></td></tr><tr><td>insulin syringe</td><td>Terumo</td><td>BS05M2913</td><td></td></tr><tr><td>hand held homogenizer</td><td>Qiagen</td><td>9001272</td><td>TissueRuptor</td></tr><tr><td>flow cytometer</td><td>BD Biosciences</td><td>N/A</td><td>Fortessa SORP&amp;nbsp;</td></tr><tr><td>Flow cytometry software</td><td>BD Biosciences</td><td>N/A</td><td>Diva</td></tr></tbody></table>

urinary tract infection in a small animal model: transurethral catheterization of male and female mice

Urinary tract infections (UTI) are extremely common worldwide, incurring significant morbidity and healthcare-associated expenses. Small animal models, which accurately reflect disease establishment and progression, permit dissection of host-pathogen interactions and generation of immunity to infection. In mice, intravesical instillation of uropathogenic E. coli, the causative agent in more than 85% of community acquired UTI, recapitulates many of the stages of infection observed in humans. Until recently, however, UTI could only be modeled in female animals. This limitation has hindered the study of sex-related differences in UTI, as well as other bladder pathologies, such as cancer. Here, we describe a method to instill male mice that allows direct comparison between female and male animals and provide a detailed protocol to assess bladder tissue by flow cytometry as a means to better understand host responses to infection. Together, these approaches will aid in the identification of host factors that contribute to sex biases observed in UTI and other bladder-associated diseases.

In the development of this protocol, cohorts of female and male C57Bl/6 mice aged 6 to 8 weeks were instilled, and bacterial burden evaluated in bladders at time points ranging from 1 hr to 30 days. The results from these studies are detailed elsewhere (Zychlinsky Scharff et al., pending). Here, we present representative data from 24 hr infections. Notably, bacterial burden was equivalent between male and female mice at 24 hr post-infection (Figure 1). Little variation in bacterial burden was observed within each group 24 hr post-infection, similar to what has been reported in female mice15,16.
If care is taken to sufficiently empty bladders of urine prior to infection, significant leakage of the inoculum is rarely observed in female mice. However, instillation into male mice resulted in significant amounts of bacterial inoculum leaking from the urethra, particularly during the development stage of this protocol. To determine whether loss of inoculum at the time of infection impacted colonization or the establishment of infection, we employed a rating system for each instillation. Each instillation was scored on a scale of 1 - 5, with 1 being the most optimal, and bacterial colonization was determined 24 hr post-infection (Figure 2, box). While this system was investigator dependent, and therefore, potentially subjective, the primary author of this study determined all scores immediately following instillation, prior to evaluation of bacterial burden in infected bladders. No statistically significant differences existed among the CFU obtained from animals with different instillation scores, as assessed by a nonparametric Kruskal-Wallis test comparing the mean rank of each column with the mean rank of every other column (p = 0.17) and correcting for multiple comparisons using a Dunn&#39;s test. From this analysis, it can be concluded that suboptimal instillations (score &#62;3), resulting in substantial leakage of bacterial inoculum during infection, do not significantly impact bacterial colonization at 24 hr (Figure 2, graph). Notably, with experience, the frequency of leaking in male mice diminished significantly.
Finally, the objective in developing this model was to directly compare the immune response to UPEC in female and male animals. To test whether cellular infiltration is altered between the sexes in response to UTI, the number of CD45+ immune cells in na&#239;ve and infected cohorts of female and male mice were assessed by flow cytometry. While the number of immune cells present in na&#239;ve animals was not different between female and male mice (p = 0.95), there was a statistically significant increase in infiltration into the bladders of infected female mice (p = 0.0015) (Figure 3A-B).
<img alt="Figure 1" src="/files/ftp_upload/54432/54432fig1.jpg" /> 
Figure 1: UPEC Colonizes Female and Male Bladders with Equal Efficiency. Six to 8 week old female and male C57Bl/6 mice were instilled with 107 CFU of UPEC. 24 hr post-infection, bladders were aseptically removed to enumerate bacterial burden. Plot depicts CFU/bladder. Each dot is one mouse, representative experiment of 5 shown. <a href="https://www.jove.com/files/ftp_upload/54432/54432fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/54432/54432fig2.jpg" /> 
Figure 2: The Quality of Instillation does not Correlate with Bacterial Burden at 24 hr Post-infection. Six to 8 week old female and male C57Bl/6 mice were instilled with 107 CFU of UPEC. Immediately after each instillation, a single researcher assigned a quality score to the instillation, as defined by specific criteria (boxed text). 24 hr post-infection, bladders were aseptically removed to enumerate bacterial burden. Plot depicts the assigned quality score versus CFU/bladder. Each dot is one mouse, 5 pooled experiments are shown. p = 0.17, Kruskal-Wallis test comparing the mean rank of each column with the mean rank of every other column with post hoc Dunn&#39;s test for multiple comparisons. <a href="https://www.jove.com/files/ftp_upload/54432/54432fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/54432/54432fig3.jpg" /> 
Figure 3: Immune Cell Infiltration is Increased in Female Mice in Response to UTI. Six to 8 week old female and male C57Bl/6 mice were instilled or not with 107 CFU of UPEC. Representative dot plots depict total bladder cells with CD45+ immune cells gated in pink from na&#239;ve or infected mice. Graph shows the absolute number of CD45+ immune cells in bladders from na&#239;ve or 24 hr infected mice. Each dot is one mouse, 2 pooled experiments are shown. p-values determined by Mann-Whitney test. <a href="https://www.jove.com/files/ftp_upload/54432/54432fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Urinary Tract Infection in a Small Animal Model: Transurethral Catheterization of Male and Female Mice at JoVE.com

Urinary Tract Infection in a Small Animal Model: Transurethral Catheterization of Male and Female Mice

The established model of transurethral catheterization of mice allows the study of bladder pathologies, including urinary tract infection, but can only be performed in females. A new model of male transurethral instillation, presented here, will enable research in an area marked by strong clinical and epidemiological differences between the sexes.

Urinary tract infections (UTI) are extremely common worldwide, incurring significant morbidity and healthcare-associated expenses. Small animal models, ...

urinary-tract-infection-small-animal-model-transurethral

Nanyang Technological University

Research

JoVE Journal

Immunology and Infection

16.5K Views.  Institut Pasteur, INSERM U818. The established model of transurethral catheterization of mice allows the study of bladder pathologies, including urinary tract infection, but can only be performed in females. A new model of male transurethral instillation, presented here, will enable research in an area marked by strong clinical and epidemiological differences between the sexes.

Video: Urinary Tract Infection in a Small Animal Model: Transurethral Catheterization of Male and Female Mice

Transurethral Induction of Mouse Urinary Tract Infection

Uropathogenic bacterial strains of interest are grown on agar. Generally, uropathogenic E. coli (UPEC) and other strains can be grown overnight on Luria-Bertani (LB) agar at 37&deg;C in ambient air. UPEC strains grow as yellowish-white translucent colonies on LB agar. Following confirmation of appropriate colony morphology, single colonies are then picked to be cultured in broth. LB broth can be used for most uropathogenic bacterial strains. Two serial, overnight LB broth cultures can be employed to enhance expression of type I pili, a well-defined virulence factor for uropathogenic bacteria. Broth cultures are diluted to the desired concentration in phosphate buffered saline (PBS). Eight to 12 week old female mice are placed under isoflurane anesthesia and transurethrally inoculated with bacteria using polyethylene tubing-covered 30 gauge syringes. Typical inocula, which must be empirically determined for each bacterial/mouse strain combination, are 106 to 108 cfu per mouse in 10 to 50 microliters of PBS. After the desired infection period (one day to several weeks), urine samples and the bladder and both kidneys are harvested. Each organ is minced, placed in PBS, and homogenized in a Blue Bullet homogenizer. Urine and tissue homogenates are serially diluted in PBS and cultured on appropriate agar. The following day, colony forming units are counted.

This video will demonstrate methods to transurethrally induce mouse urinary tract infections and quantify the extent of resulting infections.

Uropathogenic bacterial strains of interest are grown on agar. Generally, uropathogenic E. coli (UPEC) and other strains can be grown overnight on ...

Diagnosis of Ecto- and Endoparasites in Laboratory Rats and Mice

Internal and external parasites remain a significant concern in laboratory rodent facilities, and many research facilities harbor some parasitized animals. Before embarking on an examination of animals for parasites, two things should be considered. One: what use will be made of the information collected, and two: which test is the most appropriate. Knowing that animals are parasitized may be something that the facility accepts, but there is often a need to treat animals and then to determine the efficacy of treatment. Parasites may be detected in animals through various techniques, including samples taken from live or euthanized animals. Historically, the tests with the greatest diagnostic sensitivity required euthanasia of the animal, although PCR has allowed high-sensitivity testing for several types of parasite. This article demonstrates procedures for the detection of endo- and ectoparasites in mice and rats. The same procedures are applicable to other rodents, although the species of parasites found will differ.

This article describes various procedures for screening rats and mice to detect endo- or ectoparasitism. Several diagnostic assays will be demonstrated, both those suitable for use on live animals and those used after euthanasia of the animal. Photographs to aid in identification of rat and mouse parasites will be included.

Internal and external parasites remain a significant concern in laboratory rodent facilities, and many research facilities harbor some parasitized ...

Measurement of &#947;HV68 Infection in Mice

&gamma;-Herpesviruses (&gamma;-HVs) are notable for their ability to establish latent infections of lymphoid cells1. The narrow host range of human &gamma;-HVs, such as EBV and KSHV, has severely hindered detailed pathogenic studies. Murine &gamma;-herpesvirus 68 (&gamma;HV68) shares extensive genetic and biological similarities with human &gamma;-HVs and is a natural pathogen of murid rodents2. As such, evaluation of &gamma;HV68 infection of mice inbred strains at different stages of viral infection provides an important model for understanding viral lifecycle and pathogenesis during &gamma;-HVs infection.
Upon intranasal inoculation, &gamma;HV68 infection results in acute viremia in the lung that is later resolved into a latent infection of splenocytes and other cells, which may be reactivated throughout the life of the host3,4. In this protocol, we will describe how to use the plaque assay to assess infectious virus titer in the lung homogenates on Vero cell monolayers at the early stage (5 - 7 days) of post-intranasal infection (dpi). While acute infection is largely cleared 2 - 3 weeks postinfection, a latent infection of &gamma;HV68 is established around 14 dpi and maintained later on in the spleen of the mice. Latent infection usually affects a very small population of cells in the infected tissues, whereby the virus stays dormant and shuts off most of its gene expression. Latently-infected splenocytes spontaneously reactivate virus upon explanting into tissue culture, which can be recapitulated by an infectious center (IC) assay to determine the viral latent load. To further estimate the amount of viral genome copies in the acutely and/or latently infected tissues, quantitative real-time PCR (qPCR) is used for its maximal sensitivity and accuracy. The combined analyses of the results of qPCR and plaque assay, and/or IC assay will reveal the spatiotemporal profiles of viral replication and infectivity in vivo.

&#947;-Herpesviruses (&#947;-HVs) establish life-long persistency in their host. Infection of mice with &#947;-HV68 provides a genetically tractable in vivo model for the characterization of the lifecycle/pathogenesis of &#947;HVs. This protocol describes the detection and quantitation of &#947;HV68 infection at acute and latent stages following infection by plaque-forming, infectious center, and qPCR assays.

&gamma;-Herpesviruses (&gamma;-HVs) are notable for their ability to establish latent infections of lymphoid cells1. The narrow host range of human ...

Establishment and Characterization of UTI and CAUTI in a Mouse Model

Urinary tract infections (UTI) are highly prevalent, a significant cause of morbidity and are increasingly resistant to treatment with antibiotics. Females are disproportionately afflicted by UTI: 50% of all women will have a UTI in their lifetime. Additionally, 20-40% of these women who have an initial UTI will suffer a recurrence with some suffering frequent recurrences with serious deterioration in the quality of life, pain and discomfort, disruption of daily activities, increased healthcare costs, and few treatment options other than long-term antibiotic prophylaxis. Uropathogenic Escherichia coli (UPEC) is the primary causative agent of community acquired UTI. Catheter-associated UTI (CAUTI) is the most common hospital acquired infection accounting for a million occurrences in the US annually and dramatic healthcare costs. While UPEC is also the primary cause of CAUTI, other causative agents are of increased significance including Enterococcus faecalis. Here we utilize two well-established mouse models that recapitulate many of the clinical characteristics of these human diseases. For UTI, a C3H/HeN model recapitulates many of the features of UPEC virulence observed in humans including host responses, IBC formation and filamentation. For CAUTI, a model using C57BL/6 mice, which retain catheter bladder implants, has been shown to be susceptible to E. faecalis bladder infection. These representative models are being used to gain striking new insights into the pathogenesis of UTI disease, which is leading to the development of novel therapeutics and management or prevention strategies.

The ability to model urinary tract infections (UTI) is crucial in order to be able to understand bacterial pathogenesis and spawn the development of novel therapeutics. This work&#8217;s goal is to demonstrate mouse models of experimental UTI and catheter associated UTI that recapitulate and predict findings seen in humans.

Urinary tract infections (UTI) are highly prevalent, a significant cause of morbidity and are increasingly resistant to treatment with antibiotics. ...

Medicine

Transurethral Instillation Procedure in Adult Male Mouse

Transurethral instillation can be used to deliver different solutions with active ingredients (e.g., drugs, chemicals, bacteria, and viruses) locally into the urinary bladder to either induce animal models of bladder pathologies or evaluate the effectiveness of intravesical treatments. Most rodent models of lower urinary tract (LUT) pathologies are induced in female mice due to ease of intravesical instillation of the substances via the female urethra. However, due to anatomical differences between the female and male LUT, transurethral instillation in a male mouse has been deemed a very challenging procedure, and it has not been previously described. In this manuscript, we provide a detailed description of how to prepare polyethylene (PE) tubing for subsequent insertion into the urethra of a male mouse. In addition, we discuss the ideal types of PE tubing to be used depending on the desired site of inoculation. Furthermore, we describe point by point how to prepare an animal for a successful transurethral instillation to avoid injury to the urethra and ensure the delivery of the solution to the desired location. The procedure is started by retracting the prepuce and the glans to expose the opening of the urethral meatus. Next, the glans are grasped by blunt non-crushing forceps to stabilize the penis and the PE tubing. The PE tubing is first inserted into the urethral meatus parallel to the animal body, then its angle is adjusted by tilting the catheter to maneuver it to follow the natural curvature of the urethra. This technique can be used to induced murine models of bladder pathologies and/or evaluate the effectiveness of intravesical treatments in male mice.

Transurethral instillation is a challenging procedure and has not been well described in the literature. The aim of this manuscript is to describe a technique for transurethral insertion of a catheter for intravesical delivery of liquids with active substances into the urinary bladder and/or prostate in adult male mice.

Transurethral instillation can be used to deliver different solutions with active ingredients (e.g., drugs, chemicals, bacteria, and viruses) locally into ...

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.

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, ...

Evaluating the Anti-Tumor Efficacy of a Bacterial Immunomodulatory Protein in a Murine Model

Source: Codolo, G. et al. <a href="https://app.jove.com/v/52743">Evaluation of the Efficacy of the H. pylori Protein HP-NAP as a Therapeutic Tool for Treatment of Bladder Cancer in an Orthotopic Murine Model.</a>&#160;J. Vis. Exp. (2015)
This video demonstrates a technique to assess the anti-tumor activity of Helicobacter pylori neutrophil-activating protein, or HP-NAP, in a mouse bladder cancer model. HP-NAP interacts with tumor-cell neutrophils to produce pro-inflammatory cytokines, inducing the differentiation of na&#239;ve T cells into type 1 T helper (Th1) and type 1 cytotoxic (Tc1) T cell phenotypes. The Th1 and Tc1 cells secrete interferon-gamma, inhibiting tumor angiogenesis and promoting cytotoxic T cell-mediated tumor destruction, reducing tumor volume.

Ocena skuteczności przeciwnowotworowej bakteryjnego białka immunomodulującego w modelu mysim

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. ...

JoVE Encyclopedia of Experiments

Immunology

Immunotherapy

Model Development and Disease Study

Transurethral Catheterization and Bacterial Inoculation to Generate a Urinary Tract Infection Model in Male Mice

Source: Zychlinsky Scharff, A., et al. <a href="https://app.jove.com/v/54432">Urinary Tract Infection in a Small Animal Model: Transurethral Catheterization of Male and Female Mice.</a> J. Vis. Exp. (2017).
This video demonstrates the establishment of uropathogenic Escherichia coli infection in a female mouse bladder through transurethral catheter instillation. The injected bacteria successfully establish a urinary tract infection within the bladder, providing a valuable platform for studying healthcare-associated diseases related to the urinary tract.

Cewnikowanie przezcewkowe i inokulacja bakteryjna w celu wygenerowania modelu infekcji dróg moczowych u samców myszy

Immunopathology

Host-Pathogen Interaction Models

Establishment of a Urinary Tract Infection Model in Female Mice

Source: Zychlinsky Scharff, A. et al., <a href="https://app.jove.com/v/54432">Urinary Tract Infection in a Small Animal Model: Transurethral Catheterization of Male and Female Mice.</a>&#160;J. Vis. Exp. (2017)
This video demonstrates the establishment of uropathogenic Escherichia coli infection in a female mouse bladder through transurethral catheter instillation. The injected bacteria successfully establish a urinary tract infection within the bladder, providing a valuable platform for studying healthcare-associated diseases related to the urinary tract.

Opracowanie modelu infekcji dróg moczowych u samic myszy

Generating Urinary Tract Infection Model: A Technique to Administer Uropathogenic Bacteria in Mouse to Develop Urinary Tract Infection Model

Source: Luyts, N. et al., <a href="https://www.jove.com/v/62614">Longitudinal Follow-Up of Urinary Tract Infections and Their Treatment in Mice using Bioluminescence Imaging.</a> J. Vis. Exp. (2021).
In this video, we describe the technique for the intravesical administration of uropathogenic bacteria to generate a urinary tract infection model in mice. This model can be used to understand the spread of uropathogenic bacterial infection within the urinary system and the mechanisms that determine UTI susceptibility.

Generowanie modelu infekcji dróg moczowych: technika podawania bakterii uropatogennych u myszy w celu opracowania modelu infekcji dróg moczowych

Source: Luyts, N. et al., Longitudinal Follow-Up of Urinary Tract Infections and Their Treatment in Mice using Bioluminescence Imaging. J. Vis. Exp. ...