The authors would like to thank Trevor Lawley at the Wellcome Trust Sanger Institute for C. difficile R20291 spores and James S. Guy at the North Carolina State University College of Veterinary Medicine for Vero cells, both utilized in this manuscript. Animal histopathology was performed in the LCCC Animal Histopathology Core Facility at the University of North Carolina at Chapel Hill, with special assistance from Traci Raley and Amanda Brown. The LCCC Animal Histopathology Core is supported in part by an NCI Center Core Support Grant (2P30CA016086-40) to the UNC Lineberger Comprehensive Cancer Center. We would also like to thank Vincent Young, Anna Seekatz, Jhansi Leslie, and Cassie Schumacher for helpful discussions on the Vero cell cytotoxicity assay protocol. JAW is funded by the Ruth L. Kirschstein National Research Service Award Research Training grant T32OD011130 by NIH. CMT is funded by the career development award in metabolomics grant K01GM109236 by the NIGMS of the NIH.

Ethical Statement: 
The Institutional Animal Care and Use Committee (IACUC) at North Carolina State University College of Veterinary Medicine (NCSU) approved this study. The NCSU Animal Care and Use policy applies standards and guidelines set forth in the Animal Welfare Act and Health Research Extension Act of 1985. Laboratory animal facilities at NCSU adhere to guidelines set forth in the Guide for the Care and Use of Laboratory Animals. The animals&#39; health statuses were assessed daily, and moribund animal...

<ol>
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The authors have nothing to disclose at this time.

This protocol characterizes the clinical course, including weight loss, bacterial colonization, toxin cytotoxicity, and histopathological changes in the gastrointestinal tract, of antibiotic-treated mice challenged with C. difficile R20291 spores. There are several critical steps within the protocol where attention to detail is essential. Accurate calculation of the C. difficile spore inoculum is critical. This calculation is based on the original C. difficile spore stock enumeration, which sho...

Clostridium difficile is an anaerobic, gram-positive, spore-forming bacillus that causes life-threatening diarrhea1. C. difficile infection (CDI) is associated with increased human morbidity and mortality and results in over $ 4.8 billion in healthcare costs per year1-4. In 2013, the Centers for Disease Control and Prevention categorized C. difficile as an urgent antibiotic resistance risk, indicating that it poses an urgent threat to public health1. Currently, antibiotic treatment with vancomycin and metronidazole are considered the standard of care for CDI5. Unfortunately, recurrence of CDI after successful treatment with antibiotics is high, occurring in 20 - 30% of patients2,5-7. Therefore, the discovery of novel therapeutics against this enteric pathogen is necessary. To evaluate therapeutics against C. difficile, an animal model approximating the human disease in a clinically-relevant strain is needed.
Initially, Koch&#39;s postulates were established for C. difficile in 1977 using a clindamycin-treated Syrian hamster model8. This model is still utilized today to investigate the effects of C. difficile toxins on pathogenesis9,10. However, CDI in the hamster model results in high mortality rates and does not approximate the chronic insidious disease manifestations that can be seen in humans with CDI 10,11. Based on the accessibility and reagent availability of murine platforms in research, a mouse model of CDI is relevant.
In 2008, a robust mouse model of CDI was established by treating mice with an antibiotic cocktail in drinking water (kanamycin, gentamicin, colistin, metronidazole, and vancomycin) for 3 days followed by an intraperitoneal injection of clindamycin12. This rendered mice susceptible to CDI and severe colitis. Depending on the inoculum dose administered, a range of clinical signs and lethality can be observed using this model. Since this time, various antibiotic regimens have been investigated that alter the murine gut microbiota, decreasing colonization resistance to the point where C. difficile can colonize the gastrointestinal tract (reviewed in Best et al. and Lawley &#38; Young)13,14.
More recently, a broad spectrum cephalosporin, cefoperazone, given in the drinking water for 5 or 10 days reproducibly renders mice susceptible to CDI15. Since administration of third-generation cephalosporins are associated with an increased risk of CDI in humans, use of the cefoperazone model more accurately reflects naturally-occurring disease16. Cefoperazone-treated mice susceptible to C. difficile have been challenged with both C. difficile spores and vegetative cells of a variety of strains ranging in clinical relevance and virulence17. Despite some of the original studies utilizing C. difficile vegetative cells as the infectious form, C. difficile spores are considered the major mode of transmission18.
In the last decade, C. difficile R20291, a NAP1/BI/027 strain, has emerged, causing epidemics of CDI19,20. We sought to determine the clinical course of disease when cefoperazone-treated mice were challenged with the clinically-relevant and genetically-tractable C. difficile strain, R20291. This protocol details the clinical course, including weight loss, bacterial colonization, toxin cytotoxicity, and histopathological changes in the gastrointestinal tract of mice challenged with C. difficile R20291 spores. Overall, this mouse model proves to be a valuable experimental platform for CDI approximating human disease. This characterized mouse model can thus be utilized to assess the effects of novel therapeutics on the amelioration of clinical disease and on the restoration of colonization resistance against C. difficile.

<table border="0" cellpadding="0" cellspacing="0" width="1037">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:292px;">#62 Perisept Sporidicial Disinfectant Cleaner&#160;</td>
			<td style="width:143px;">SSS Navigator</td>
			<td style="width:119px;">48027</td>
			<td style="width:483px;">This product will require dilution as recommended by the manufacturer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.22 &#956;m filter</td>
			<td>Fisherbrand</td>
			<td>09-720-3</td>
			<td>Alternative to filter plate for indivdiual samples tested in the Vero Cell Assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.25% Trypsin-EDTA</td>
			<td>Gibco</td>
			<td>25200-056</td>
			<td>Needs to be heated in water bath at 37C prior to use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.4% Trypan Blue</td>
			<td>Gibco</td>
			<td>15250-061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1% Peniciilin/Streptomycin</td>
			<td>Gibco</td>
			<td>15070-063</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10% heat inactivated FBS</td>
			<td>Gibco</td>
			<td>16140-071</td>
			<td>Needs to be heated in water bath at 37C prior to use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1ml plastic syringe&#160;</td>
			<td>BD Medical Supplies</td>
			<td>309628</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1X PBS</td>
			<td>Gibco</td>
			<td>10010-023</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2 ml Micro Centrifuge Screw Cap</td>
			<td>Corning</td>
			<td>430917</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">96 well cell culture flat bottom plate</td>
			<td>Costar Corning</td>
			<td>CL3595</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">96 well filter plate</td>
			<td>Millipore</td>
			<td>MSGVS2210</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Adhesive Seal</td>
			<td>ThermoScientific</td>
			<td>AB-0558</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:292px;">Bacto Agar</td>
			<td style="width:143px;">Becton Dickinson</td>
			<td style="width:119px;">214010</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:292px;">Bacto Proteose Peptone</td>
			<td style="width:143px;">Becton Dickinson</td>
			<td style="width:119px;">211684</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cefoperazone</td>
			<td>MP Bioworks</td>
			<td>199695</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cefoxitine</td>
			<td>Sigma</td>
			<td>C47856</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Clostridium difficile Antitoxin Kit</td>
			<td>Tech Labs</td>
			<td>T5000</td>
			<td>Used as control for Vero Cell Assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Clostridium difficile Toxin A</td>
			<td>List Biological Labs</td>
			<td>152C</td>
			<td>Positive control for Vero Cell Assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">D-cycloserine</td>
			<td>Sigma</td>
			<td>C6880</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Distilled Water</td>
			<td>Gibco</td>
			<td>15230</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMEM 1X Media</td>
			<td>Gibco</td>
			<td>11965-092</td>
			<td>Needs to be heated in water bath at 37C prior to use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fructose</td>
			<td>Fisher</td>
			<td>L95500</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hemocytometer</td>
			<td>Bright-Line, Sigma</td>
			<td>Z359629</td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:292px;">KH2PO4</td>
			<td style="width:143px;">Fisher</td>
			<td style="width:119px;">P285-500</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:292px;">MgSO4 (anhydrous)</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">M2643</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:292px;">Millex-GS 0.22 &#956;m filter</td>
			<td style="width:143px;">Millex-GS</td>
			<td style="width:119px;">SLGS033SS</td>
			<td style="width:483px;">Filter for TCCFA plates&#160;</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:292px;">Na2HPO4</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">S-0876</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NaCl</td>
			<td style="width:143px;">Fisher</td>
			<td style="width:119px;">S640-3</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Number 10 disposable scalpel blade</td>
			<td>Miltex, Inc</td>
			<td>4-410</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PCR Plates</td>
			<td>Fisherbrand</td>
			<td>14230244</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Plastic petri dish</td>
			<td>Kord-Valmark Brand</td>
			<td>2900</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile plastic L-shaped cell spreader</td>
			<td>Fisherbrand</td>
			<td>14-665-230</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Syringe Stepper</td>
			<td>Dymax Corporation</td>
			<td>T15469</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Taurocholate</td>
			<td>Sigma</td>
			<td>T4009</td>
			<td>Part of TCCFA plates (see below)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultrapure distilled water</td>
			<td>Invitrogen</td>
			<td>10977-015</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:292px;">C57BL/6J Mice</td>
			<td style="width:143px;">The Jackson Laboratory</td>
			<td align="right" style="width:119px;">664</td>
			<td style="width:483px;">Mice should be 5-8 weeks of age</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Olympus BX43F light microscope</td>
			<td style="width:143px;">Olympus Life Science</td>
			<td style="width:119px;"></td>
			<td style="width:483px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">DP27 camera</td>
			<td style="width:143px;">Olympus Life Science</td>
			<td style="width:119px;"></td>
			<td style="width:483px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">cellSens Dimension software&#160;</td>
			<td style="width:143px;">Olympus Life Science</td>
			<td style="width:119px;"></td>
			<td style="width:483px;"></td>
		</tr>
	</tbody>
</table>

cefoperazone-treated mouse model of clinically-relevant clostridium difficile strain r20291

Clostridium difficile is an anaerobic, gram-positive, spore-forming enteric pathogen that is associated with increasing morbidity and mortality and consequently poses an urgent threat to public health. Recurrence of a C. difficile infection (CDI) after successful treatment with antibiotics is high, occurring in 20-30% of patients, thus necessitating the discovery of novel therapeutics against this pathogen. Current animal models of CDI result in high mortality rates and thus do not approximate the chronic, insidious disease manifestations seen in humans with CDI. To evaluate therapeutics against C. difficile, a mouse model approximating human disease utilizing a clinically-relevant strain is needed. This protocol outlines the cefoperazone mouse model of CDI using a clinically-relevant and genetically-tractable strain, R20291. Techniques for clinical disease monitoring, C. difficile bacterial enumeration, toxin cytotoxicity, and histopathological changes throughout CDI in a mouse model are detailed in the protocol. Compared to other mouse models of CDI, this model is not uniformly lethal at the dose administered, allowing for the observation of a prolonged clinical course of infection concordant with the human disease. Therefore, this cefoperazone mouse model of CDI proves a valuable experimental platform to assess the effects of novel therapeutics on the amelioration of clinical disease and on the restoration of colonization resistance against C. difficile.

During a representative study, 5-week-old C57BL/6 WT mice were pretreated with cefoperazone in their drinking water (0.5 mg/ml) for 5 days and allowed a 2-day wash out with regular drinking water. Mice were challenged with 105 spores of C. difficile R20291 via oral gavage on day 0 (Figure 1A). Mice were monitored for weight loss and clinical signs (lethargy, inappetence, diarrhea, and hunched posture) of CDI for 14 days. The challenge of C57BL/6 WT mic...

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Cefoperazone-treated Mouse Model of Clinically-relevant Clostridium difficile Strain R20291

This protocol outlines the cefoperazone mouse model of Clostridium difficile infection (CDI) using a clinically-relevant and genetically-tractable strain, R20291. Emphasis on clinical disease monitoring, C. difficile bacterial enumeration, toxin cytotoxicity, and histopathological changes throughout CDI in a mouse model are detailed in the protocol.

Cefoperazone-treated Mouse Model of Clinically-relevant Clostridium difficile Strain R20291

Clostridium difficile is an anaerobic, gram-positive, spore-forming enteric pathogen that is associated with increasing morbidity and mortality and ...

The overall goal of this protocol is to provide a step by step guide for implementing the cefoperazone mouse model of Clostridium difficile infection, with special emphasis on clinical disease monitoring, bacteria enumeration, toxin cytotoxicity, and histopathologic changes post challenge. This detailed protocol will help researchers accurately execute a mouse model of Clostridium difficile infection, which is essential for studying the pathogenesis of this bacterium and accessing novel therapeutics. The main advantage of using this mouse model is that exposure to one antibiotic for five days renders mice susceptible to colonization of C.difficile and for a prolonged clinical course of infection concurrent with human disease.To begin, take the C.difficile stock strain of interest and vortex. In a laminar flow hood, dilute the stock in sterile water in a screw cap tube to a concentration of ten to the fifth spores per 25 microliters. Label the mixture as spore inoculum and place the tube into a 65 degree Celsius water bath for 20 minutes.Next, in the laminar flow hood, pipette 50 microliters of the heated spore inoculum into a sterile microcentrifuge tube and pass it into the anaerobic chamber until further use. Load the remaining spore inoculum into a one milliliter syringe attached to a sterile bulb tipped gastric gavage needle. In a laminar flow hood, take a subject mouse and immobilize the head by restraining the animal gently by the loose skin of the neck and back.Using the index finger, and ensuring the animal does not vocalize or show signs of distress, further immobilize the animal's head and elongate the esophagus. Maintain the mouse in an upright, vertical position and gently pass the gavage needle into the side of the mouth. Direct the gavage needle along the roof of the mouth and slowly advance it into the esophagus.Once the needle is approximately halfway into the esophagus, inject 25 microliters of spore inoculum and then gently withdraw the needle. Return the animal to its cage, and observe it for any signs of coughing or respiratory distress that may indicate inadvertent tracheal administration. Next, take the spore inoculum aliquot stored previously in the anaerobic chamber, and any remaining gavage spore inoculum, and make one to ten serial dilutions in 180 microliters of 1x PBS.Perform four to five of these dilutions. Using aseptic technique, transfer 100 microliters of each serial dilution into an individual TCCFA plate. Taking a new sterile L-shaped spreader each time, evenly distribute the dilution inocula on each plate.Incubate the plates under anaerobic conditions for 24 hours at 37 degrees Celsius. Finally, count the C.difficile colonies on each dilution plate and calculate the colony forming units to obtain the infective dose administered to the mice. To collect fecal samples from mice for assessment, first lightly but firmly restrain the subject mouse by the loose skin on the neck and back, ensuring the animal is not in distress.Using the pinky finger, gently lift the animal's tail, exposing the anus. Hold a sterile microcentrifuge tube of known weight directly under the animal's anus, ensuring the tube does not directly touch the mouse. When the animal defecates, collect the fecal pellet in the tube.Store the tube at room temperature until all necessary samples are collected. Weigh the tubes containing feces on an analytical scale and record the mass to four decimal places. Calculate the weight of the fecal pellet by subtracting the weight of the tube.Next, calculate a one to ten dilution of the contents and resuspend into 1x PBS. Use the tip of the pipette to gently disrupt the fecal matter into solution. Incubate the samples at room temperature for 30 minutes, allowing the contents to settle.Maintaining the solutions anaerobically, make serial dilutions for each sample in 1x PBS. Transfer 100 microliters of each serial dilution onto TCCFA plates. Use a sterile L-shaped spreader and evenly apply the media to the plates.Incubate the plates in anaerobic conditions at 37 degrees celsius for 24 hours. Finally, enumerate the C.difficile colonies and calculate the colony forming unit per gram of fecal content. This figure shows mouse weight in the days following challenge with C.difficile R20291.At day zero, the baseline weight is set to 100. Average mouse bodyweight was measured each day following, for 14 days. A significant decrease in weight was observed in challenged mice on days two to seven post challenge.Mice appeared to recover and regain weight after this point. Here, C.difficile load in the feces in the days post challenge are shown. At 24 hours post challenge, all mice were colonized with 10 to the seventh CFUs per gram of feces.This load had decreased by day seven onwards, though C.difficile is still present. Histopathologic examination of mice over the time course of the infection showed the most significant pathologic changes in the cecum. Total cecal histologic scores were significantly different between day zero and days two and four post challenge.Generally, individuals new to this mouse model may struggle with the calculation and preparation of the spore inoculum used to challenge the mice and the calculation of fecal C.difficile bacterial load. While attempting this protocol it's important to remember that modifications of the dose or strain of C.difficile spores administered to mice may alter the outcome of this model.

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Research

JoVE Journal

Immunology and Infection

12.1K visualizações.  North Carolina State University College of Veterinary Medicine. The overall goal of this protocol is to provide a step by step guide for implementing the cefoperazone mouse model of Clostridium difficile infection, with special emphasis on clinical disease monitoring, bacteria enumeration, toxin cytotoxicity, and histopathologic changes post challenge. This detailed protocol will help researchers accurately execute a mouse model of Clostridium difficile infection, which is essential for studying the pathogenesis of this bacterium and accessing novel thera...