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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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis+and+treatment+of+uncomplicated+urinary+tract+infection.">Diagnosis and treatment of uncomplicated urinary tract infection.</a> Infect Dis Clin North Am. 11 (3), 551-581 (1997).</li><li>Harper, M., Fowlis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Management+of+urinary+tract+infections+in+men.">Management of urinary tract infections in men.</a> Trends in Urology, Gynaecology &amp; Sexual Health. 12 (1), 30-35 (2007).</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> Nat Rev Urol. 7 (12), 653-660 (2010).</li><li>Lipsky, B. A. <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+infections+in+men.+Epidemiology,+pathophysiology,+diagnosis,+and+treatment.">Urinary tract infections in men. Epidemiology, pathophysiology, diagnosis, and treatment.</a> Ann Intern Med. 110 (2), 138-150 (1989).</li><li>Conway, L. J., Carter, E. J., Larson, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Risk+Factors+for+Nosocomial+Bacteremia+Secondary+to+Urinary+Catheter-Associated+Bacteriuria:+A+Systematic+Review.">Risk Factors for Nosocomial Bacteremia Secondary to Urinary Catheter-Associated Bacteriuria: A Systematic Review.</a> Urol Nurs. 35 (4), 191-203 (2015).</li><li>Markle, J. G., Fish, E. 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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 vis...

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 border="0" cellpadding="0" cellspacing="0" width="808">
	<tbody>
		<tr height="45">
			<td height="45" style="height:45px;width:283px;">BD Insyte Autoguard Shielded IV Catheters 24G, 0.7 mm external diameter, 14 mM long</td>
			<td style="width:131px;">BD Medical</td>
			<td style="width:135px;">381811 or 381411*</td>
			<td style="width:260px;">* catalog number is country-dependent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">inoculating loop</td>
			<td style="width:131px;">Greiner Bio-One</td>
			<td style="width:135px;">731171</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">LB Miller broth</td>
			<td style="width:131px;">Difco</td>
			<td style="width:135px;">244620</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">LB Miller agar</td>
			<td style="width:131px;">Difco</td>
			<td style="width:135px;">244520</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Cuvettes</td>
			<td style="width:131px;">Bio-rad</td>
			<td style="width:135px;">223-9955</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">syringes</td>
			<td style="width:131px;">B Braun</td>
			<td style="width:135px;">9166017V</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Thumb (Adson) forceps</td>
			<td style="width:131px;">Fine Science Tools</td>
			<td style="width:135px;">11006-12</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">5 mL tubes, polypropylene</td>
			<td style="width:131px;">Falcon</td>
			<td style="width:135px;">352063</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Tissue Ruptor disposable probes</td>
			<td style="width:131px;">Qiagen</td>
			<td style="width:135px;">990890</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">15 mL flip cap tubes</td>
			<td style="width:131px;">Thermo Scientific</td>
			<td style="width:135px;">362694</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">DNAse</td>
			<td style="width:131px;">Invitrogen</td>
			<td style="width:135px;">18047019</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:283px;">Liberase TM</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:135px;">5401119001</td>
			<td style="width:260px;">should be aliquotted and stored at -20 &#176;C to avoid repeated freeze-thaw</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:283px;">100 &#181;M MACS SmartStrainers&#160;</td>
			<td style="width:131px;">Miltenyi</td>
			<td style="width:135px;">130-098-463</td>
			<td style="width:260px;">compatible with 15 mL tubes, preferred</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:283px;">100 &#181;m cell strainers&#160;</td>
			<td style="width:131px;">Falcon</td>
			<td style="width:135px;">352360</td>
			<td style="width:260px;">compatible with 50 mL tubes, if MACS Smart Strainers are not available</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">96 well plate</td>
			<td style="width:131px;">Falcon</td>
			<td style="width:135px;">353077</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Fc block</td>
			<td style="width:131px;">BD Pharmingen</td>
			<td style="width:135px;">553142</td>
			<td style="width:260px;">anti-CD16/CD32</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:283px;">anti-mouse CD45 antibody</td>
			<td style="width:131px;">BD Biosciences</td>
			<td style="width:135px;">561487</td>
			<td style="width:260px;">many different fluorescent conjugation options are available</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">5 mL tubes polystyrene with filter cap</td>
			<td style="width:131px;">Falcon</td>
			<td style="width:135px;">352235</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">insulin syringe</td>
			<td style="width:131px;">Terumo</td>
			<td style="width:135px;">BS05M2913</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">hand held homogenizer</td>
			<td style="width:131px;">Qiagen</td>
			<td style="width:135px;">9001272</td>
			<td style="width:260px;">TissueRuptor</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">flow cytometer</td>
			<td style="width:131px;">BD Biosciences</td>
			<td style="width:135px;">N/A</td>
			<td style="width:260px;">Fortessa SORP&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Flow cytometry software</td>
			<td style="width:131px;">BD Biosciences</td>
			<td style="width:135px;">N/A</td>
			<td style="width:260px;">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 var...

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

Research

JoVE Journal

Immunology and Infection

16.3K 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 ...

Isolation of Lymphocytes from Mouse Genital Tract Mucosa

Mucosal surfaces, including in the gastrointestinal, urogenital, and respiratory tracts, provide portals of entry for pathogens, such as viruses and bacteria 1. Mucosae are also inductive sites in the host to generate immunity against pathogens, such as the Peyers patches in the intestinal tract and the nasal-associated lymphoreticular tissue in the respiratory tract. This unique feature brings mucosal immunity as a crucial player of the host defense system. Many studies have been focused on gastrointestinal and respiratory mucosal sites. However, there has been little investigation of reproductive mucosal sites. The genital tract mucosa is the primary infection site for sexually transmitted diseases (STD), including bacterial and viral infections. STDs are one of the most critical health challenges facing the world today. Centers for Disease Control and Prevention estimates that there are 19 million new infectious every year in the United States. STDs cost the U.S. health care system $17 billion every year 2, and cost individuals even more in immediate and life-long health consequences. In order to confront this challenge, a greater understanding of reproductive mucosal immunity is needed and isolating lymphocytes is an essential component of these studies. Here, we present a method to reproducibly isolate lymphocytes from murine female genital tracts for immunological studies that can be modified for adaption to other species. The method described below is based on one mouse.&#x2003;

An efficient way to isolate lymphocytes from mouse genital tract is described. This method takes advantage of enzyme digestion and Percoll gradient separation to allow efficient isolation. This technique is also adaptable to for use in other species

Mucosal surfaces, including in the gastrointestinal, urogenital, and respiratory tracts, provide portals of entry for pathogens, such as viruses and ...

4D Multimodality Imaging of Citrobacter rodentium Infections in Mice

This protocol outlines the steps required to longitudinally monitor a bioluminescent bacterial infection using composite 3D diffuse light imaging tomography with integrated &mu;CT (DLIT-&mu;CT) and the subsequent use of this data to generate a four dimensional (4D) movie of the infection cycle. To develop the 4D infection movies and to validate the DLIT-&mu;CT imaging for bacterial infection studies using an IVIS Spectrum CT, we used infection with bioluminescent C. rodentium, which causes self-limiting colitis in mice. In this protocol, we outline the infection of mice with bioluminescent C. rodentium and non-invasive monitoring of colonization by daily DLIT-&mu;CT imaging and bacterial enumeration from feces for 8 days.
The use of the IVIS Spectrum CT facilitates seamless co-registration of optical and &mu;CT scans using a single imaging platform. The low dose &mu;CT modality enables the imaging of mice at multiple time points during infection, providing detailed anatomical localization of bioluminescent bacterial foci in 3D without causing artifacts from the cumulative radiation. Importantly, the 4D movies of infected mice provide a powerful analytical tool to monitor bacterial colonization dynamics in vivo.

4D Multimodality Imaging of Citrobacter rodentium Infections in Mice

Multi-modality imaging is a valuable approach for studying bacterial colonization in small animal models. This protocol outlines infection of mice with bioluminescent Citrobacter rodentium and the longitudinal monitoring of bacterial colonization using composite 3D diffuse light imaging tomography with &mu;CT imaging to create a 4D movie of C. rodentium infection.

This protocol outlines the steps required to  longitudinally monitor a bioluminescent bacterial infection using composite 3D diffuse light imaging ...

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 ...

Isolation of Dendritic Cells from the Human Female Reproductive Tract for Phenotypical and Functional Studies

The characterization of the human dendritic cells (DCs) resident in mucosal tissues is challenging due to the difficulty in obtaining samples, and the low numbers of DCs present per tissue. Yet, as the phenotype and function of DCs is modified by the tissue environment, it is necessary to analyze tissue resident DC populations, since blood derived DCs incompletely reflect the complexities of DCs in tissues. Here we present a protocol to isolate DCs from the human female reproductive tract (FRT) using hysterectomy specimens that allows both phenotypical and functional analyses. The protocol consists of tissue digestion to generate a single cell mixed cell suspension, followed by positive magnetic bead selection. Our tissue digestion protocol does not cleave surface markers, which allows phenotypical and functional analysis of DCs in the steady state, without overnight incubation or cell activation. This protocol can be adapted for the isolation of other immune cell types or isolation of DCs from other tissues.

We describe here a method to isolate and purify dendritic cells from different anatomical compartments in the human female reproductive tract for the evaluation of their phenotypical and functional characteristics. This method can be adapted to isolate other immune cells or dendritic cells from other mucosal tissues.

The characterization of the human dendritic cells (DCs) resident in mucosal tissues is challenging due to the difficulty in obtaining samples, and the low ...

Intracranial Subarachnoidal Route of Infection for Investigating Roles of Streptococcus suis Biofilms in Meningitis in a Mouse Infection Model

Streptococcus suis is not only a major bacterial pathogen of pigs worldwide but also an emerging zoonotic agent. In humans and pigs, meningitis is a major manifestation of S. suis infections. A suitable infection model is an essential tool to understand the mechanisms of diseases caused by pathogens. Several routes of infection in mice have been developed to study the pathogenesis of S. suis infection. However, the intraperitoneal, intranasal, and intravenous routes of infection are not suitable for studying the roles of S. suis surface components in meningitis directly in the brain, such as the extracellular matrix from biofilms. Although intracisternal inoculation has been used for S. suis infection, the precise injection site has not been described. Here, the intracranial subarachnoidal route of infection was described in a mouse model to investigate the roles of biofilms in S. suis meningitis. S. suis planktonic cells or biofilm state cells were directly injected into the subarachnoid space of mice through the injection site located 3.5 mm rostral from the bregma. Histopathological analysis and increased mRNA expression of TLR2 and cytokines of the brain tissue from mice injected with biofilm state cells clearly indicated that S. suis biofilm plays definitive roles in S. suis meningitis. This route of infection has obvious advantages over other routes of infection, allowing the study of the host-bacterium interaction. Furthermore, it permits the effect of bacterial components on host immune responses directly in the brain to be assessed, and mimics bacterial entrance into the central nervous system. This route of infection can be extended for investigating the mechanisms of meningitis caused by other bacteria. In addition, it can also be used to test the efficacy of drugs against bacterial meningitis.

Intracranial Subarachnoidal Route of Infection for Investigating Roles of Streptococcus suis Biofilms in Meningitis in a Mouse Infection Model

Here, we describe the intracranial subarachnoidal route of infection in mice to study roles of biofilms in Streptococcus suis meningitis. This infection model is also suitable for studying the pathogenesis of other bacterial meningitis and the efficacy of new drugs against bacterial meningitis.

Streptococcus suis is not only a major bacterial pathogen of pigs worldwide but also an emerging zoonotic agent. In humans and pigs, meningitis is a major ...

Isolation of Single Intracellular Bacterial Communities Generated from a Murine Model of Urinary Tract Infection for Downstream Single-cell Analysis

In this article, we outline a procedure used to isolate individual intracellular bacterial communities from a mouse that has been experimentally infected in the urinary tract. The protocol can be broadly divided into three sections: the infection, bladder epithelial cell harvesting, and mouth micropipetting to isolate individual infected epithelial cells. The isolated epithelial cell contains viable bacterial cells and is nearly free of contaminating extracellular bacteria, making it ideal for downstream single-cell analysis. The time taken from the start of infection to obtaining a single intracellular bacterial community is about 8 h. This protocol is inexpensive to deploy and uses widely available materials, and we anticipate that it can also be utilized in other infection models to isolate single infected cells from cell mixtures even if those infected cells are rare. However, due to a potential risk in mouth micropipetting, this procedure is not recommended for highly infectious agents.

This protocol describes a simple method of isolating single, infected-bladder epithelial cells from a murine model of urinary tract infection.

In this article, we outline a procedure used to isolate individual intracellular bacterial communities from a mouse that has been experimentally infected ...

A Non-Coding Small RNA MicC Contributes to Virulence in Outer Membrane Proteins in Salmonella Enteritidis

A non-coding small RNA (sRNA) is a new factor to regulate gene expression at the post-transcriptional level. A kind of sRNA MicC, known in Escherichia coli and Salmonella Typhimurium, could repress the expression of outer membrane proteins. To further investigate the regulation function of micC in Salmonella Enteritidis, we cloned the micC gene in the Salmonella Enteritidis strain 50336, and then constructed the mutant 50336&#916;micC by the &#955; Red-based recombination system and the complemented mutant 50336&#916;micC/pmicC carrying recombinant plasmid pBR322 expressing micC. qRT-PCR results demonstrated that transcription of ompD in 50336&#916;micC was 1.3-fold higher than that in the wild type strain, while the transcription of ompA and ompC in 50336&#916;micC were 2.2-fold and 3-fold higher than those in the wild type strain. These indicated that micC represses the expression of ompA and ompC. In the following study, the pathogenicity of 50336&#916;micC was detected by both infecting 6-week-old Balb/c mice and 1-day-old chickens. The result showed that the LD50 of the wild type strain 50336, the mutants 50336&#916;micC and 50336&#916;micC/pmicC for 6-week-old Balb/c mice were 12.59 CFU, 5.01 CFU, and 19.95 CFU, respectively. The LD50 of the strains for 1-day-old chickens were 1.13 x 109 CFU, 1.55 x 108 CFU, and 2.54 x 108 CFU, respectively. It indicated that deletion of micC enhanced virulence of S. Enteritidis in mice and chickens by regulating expression of outer membrane proteins.

A Non-Coding Small RNA MicC Contributes to Virulence in Outer Membrane Proteins in Salmonella Enteritidis

An &#955;-Red-mediated recombination system was used to create a deletion mutant of a small non-coding RNA micC.

A non-coding small RNA (sRNA) is a new factor to regulate gene expression at the post-transcriptional level. A kind of sRNA MicC, known in Escherichia ...