Patients' experiences and perspectives of post-hospital follow-up care to improve physical recovery for intensive care survivors: A systematic review of qualitative research.

Background: Intensive care units deliver care to a heterogeneous group of patients with pre-existing co-morbid disease. Focus has shifted to improving health related quality of life with more patients surviving beyond hospital discharge. Randomised controlled trials evaluating follow-up interventions, to improve physical recovery, have not demonstrated a health-related quality of life benefit. Qualitative research may provide the context to understand the experiences of intensive care survivors during follow-up care addressing physical limitations. Objective: To synthesise qualitative studies and explore Intensive Care survivors' experiences and perspectives of physical symptoms in the context of follow-up care. Settings: A systematic search of electronic databases (MEDLINE, Cumulative Index of Nursing and Allied Health Literature, Web of Science, Applied Social Sciences Index and Abstracts, Ovid Nursing and Ovid Emcare) was conducted to identify peer-reviewed primary qualitative studies. No date parameters were applied. Inclusion/exclusion criteria guided the screening process. Participants: The data from eligible primary research studies was extracted into NVivo (v12). Methods: Critical appraisal was completed using the Joanna Briggs Critical Appraisal Tool. Thematic analysis, guided by Braun and Clarke (2022), informed the data synthesis. Results: From 2457 studies, ten relevant studies were included. Two main themes were identified: 1. Recovery as uncertain; which outlines the uncertainty experienced by intensive care unit survivors during recovery. This theme pertained to system-level factors (role of healthcare professional and information provision) which provides the context for delivering follow-up care. 2. Self-determination of recovery; outlines individual characteristics in determining recovery which is conceptualised by patient-level factors (motivation, support network and perception of health). Conclusions: For intensive care survivors, the recovery trajectory is uncertain with a gap in information provision during the acute phase following hospital discharge. Patients' self-determination of recovery is an important consideration to ensure follow-up care addresses the needs of individual patients. The impact of pre-existing co-morbid disease and subgroups of patients deriving benefit from follow-up care remains uncertain. Registration: PROSPERO Registration no. CRD42022355711. Tweetable abstract: Patients' experiences of post-hospital follow-up care to improve physical recovery for intensive care survivors: A Systematic Review of Qualitative Research.

The rise of veterinary forensics.

Veterinary forensics is rapidly emerging as a distinct branch of veterinary medicine, especially because of increasing mindfulness about animal cruelty, and of the link between acts of cruelty to animals and violence toward humans. Nevertheless, the application of forensic sciences in veterinary cases lags behind its application in medical cases. Although gaps persist in veterinarians' knowledge of forensics and in how to apply this field to medicolegal cases involving animals, continued research and publication in veterinary forensics are rapidly developing the evidence base in this area. Additionally, educational opportunities in veterinary forensics are also increasing at both undergraduate and postgraduate levels. Together, these changes will continue to improve veterinarians' abilities to investigate cases involving animals. To further strengthen these investigations, veterinarians should also collaborate with the appropriate experts in different disciplines of forensic science.

COVID-19 and pets: When pandemic meets panic.

As the novel coronavirus outbreak spreads globally with devastating effects on human health, pets are also becoming unnecessary victims amidst the pandemic panic. Many have been reluctantly left home alone by owners who have been forced to temporarily evacuate their homes. And, although no evidence exists to indicate that they can either transmit the virus or develop its associated coronavirus disease 2019 (COVID-19), fear among the public that pets might play a role in spreading COVID-19 has resulted in pets being abandoned or even killed. This article outlines some of the ways in which the current pandemic has negatively impacted the welfare of pets. It also highlights the relationships between animal, human, and environmental health, as well as the importance of taking a collaborative transdisciplinary One Health approach to help prevent future COVID-19 outbreaks.

Mice Deficient in Epithelial or Myeloid Cell Iκκß Have Distinct Colonic Microbiomes and Increased Resistance to Citrobacter rodentium Infection.

The colonic microenvironment, stemming from microbial, immunologic, stromal, and epithelial factors, serves as an important determinant of the host response to enteric pathogenic colonization. Infection with the enteric bacterial pathogen Citrobacter rodentium elicits a strong mucosal Th1-mediated colitis and monocyte-driven inflammation activated via the classical NF-κB pathway. Research has focused on leukocyte-mediated signaling as the main driver for C. rodentium-induced colitis, however we hypothesize that epithelial cell NF-κB also contributes to the exacerbation of infectious colitis. To test this hypothesis, compartmentalized classical NF-κB defective mice, via the deletion of IKKß in either intestinal epithelial cells (IKKßΔIEC) or myeloid-derived cells (IKKßΔMY), and wild type (WT) mice were challenged with C. rodentium. Both pathogen colonization and colonic histopathology were significantly reduced in IKKß-deficient mice compared to WT mice. Interestingly, colonic IL-10, RegIIIγ, TNF-α, and iNOS gene expression were increased in IKKß-deficient mice in the absence of bacterial challenge. This was associated with increased p52, which is involved with activation of NF-κß through the alternative pathway. IKKß-deficient mice also had distinct differences in colonic tissue-associated and luminal microbiome that may confer protection against C. rodentium. Taken together, these data demonstrate that classical NF-κB signaling can lead to enhanced enteric pathogen colonization and resulting colonic histopathology.

Enterohepatic Helicobacter spp. in cats with non-haematopoietic intestinal carcinoma: a survey of 55 cases.

Several enterohepatic Helicobacter spp. (EHS) have been isolated from cats. Despite the reported association between EHS infection and intestinal neoplasia in other species, this association has not been explored in cats. In this study, 55 non-haematopoietic feline intestinal carcinoma cases were histopathologically evaluated. In contrast with prior reports, large intestinal (LI) carcinoma was observed with greater frequency (61 %) relative to small intestinal (SI) carcinoma (35 %). There was a significant association between intestinal location and animal gender. Of males examined, 83 % had LI carcinoma, while no such trend was observed in females. Previously described associations between Siamese breed and intestinal carcinoma could not be definitively confirmed, although the Siamese breed may be predisposed to SI carcinoma location. Of all carcinomas examined in this study, 62 % were classified as adenocarcinoma, although mucinous adenocarcinoma (28 %) and solid carcinoma (11 %) were also identified. Tumours were all moderately or poorly differentiated. When considered by intestinal location and histopathologic classification, LI adenocarcinoma was associated with significantly advanced mean age (13 years) when compared to SI adenocarcinoma and LI mucinous adenocarcinoma (mean, 9 years in both cases), which were also frequently encountered. To determine whether EHS might play a role in feline intestinal neoplasia, Helicobacter genus- and species-specific fluorescence in situ hybridization was performed. Of these carcinoma cases, 56 % were positive for Helicobacter spp. and one or more species-specific assay for Helicobacterbilis, Helicobactercanis or Helicobactermarmotae. The presence of EHS was significantly associated with both LI location (68 %) and mucinous adenocarcinoma (92 %). These findings suggest a role for intestinal bacteria in non-haematopoietic feline intestinal neoplasia.

Persistent effect of mTOR inhibition on preneoplastic foci progression and gene expression in a rat model of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a heterogeneous disease in which tumor subtypes can be identified based on the presence of adult liver progenitor cells. Having previously identified the mTOR pathway as critical to progenitor cell proliferation in a model of liver injury, we investigated the temporal activation of mTOR signaling in a rat model of hepatic carcinogenesis. The model employed chemical carcinogens and partial hepatectomy to induce progenitor marker-positive HCC. Immunohistochemical staining for phosphorylated ribosomal protein S6 indicated robust mTOR complex 1 (mTORC1) activity in early preneoplastic lesions that peaked during the first week and waned over the subsequent 10 days. Continuous administration of rapamycin by subcutaneous pellet for 70 days markedly reduced the development of focal lesions, but resulted in activation of the PI3K signaling pathway. To test the hypothesis that early mTORC1 activation was critical to the development and progression of preneoplastic foci, we limited rapamycin administration to the 3-week period at the start of the protocol. Focal lesion burden was reduced to a degree indistinguishable from that seen with continuous administration. Short-term rapamycin did not result in the activation of PI3K or mTORC2 pathways. Microarray analysis revealed a persistent effect of short-term mTORC1 inhibition on gene expression that resulted in a genetic signature reminiscent of normal liver. We conclude that mTORC1 activation during the early stages of hepatic carcinogenesis may be critical due to the development of preneoplastic focal lesions in progenitor marker-positive HCC. mTORC1 inhibition may represent an effective chemopreventive strategy for this form of liver cancer.

Struvite Urolithiasis in Long-Evans Rats.

Struvite urinary calculi, which are composed of magnesium, ammonium, and phosphate, can cause complications including sepsis and renal failure. Struvite calculi were identified within the urinary bladder and renal pelvis of 2 Long-Evans rats that died within days after arrival from a commercial vendor. The remaining rats in the shipment were screened by physical examination, radiography, and ultrasonography, revealing an additional 2 animals that were clinically affected. These rats were euthanized, necropsied, and yielded similar findings to those from the first 2 rats. In addition, urine samples had an alkaline pH and contained numerous bacteria (predominantly Proteus mirabilis), leukocytes, and crystals. All calculi were composed completely of struvite. Another 7 rats in the shipment had alkaline urine with the presence of blood cells; 6 of these rats also had abundant struvite crystals, and P. mirabilis was cultured from the urine of 3 rats. Further investigation by the vendor identified 2 of 100 rats with struvite calculi from the same colony. Although no specific cause could be implicated, the fact that all the affected rats came from the same breeding area suggests a genetic or environmental triggering event; a contribution due to diet cannot be ruled out. Our findings suggest that the affected rats had metabolic disturbances coupled with bacterial infection that predisposed them to develop struvite calculi. During sudden increases of struvite urinary calculi cases in rats, urine cultures followed by appropriate surgical intervention and antibiotic therapy is warranted. Additional factors, including diet, merit attention as well.

Helicobacter hepaticus infection promotes hepatitis and preneoplastic foci in farnesoid X receptor (FXR) deficient mice.

Farnesoid X receptor (FXR) is a nuclear receptor that regulates bile acid metabolism and transport. Mice lacking expression of FXR (FXR KO) have a high incidence of foci of cellular alterations (FCA) and liver tumors. Here, we report that Helicobacter hepaticus infection is necessary for the development of increased hepatitis scores and FCA in previously Helicobacter-free FXR KO mice. FXR KO and wild-type (WT) mice were sham-treated or orally inoculated with H. hepaticus. At 12 months post-infection, mice were euthanized and liver pathology, gene expression, and the cecal microbiome were analyzed. H. hepaticus induced significant increases hepatitis scores and FCA numbers in FXR KO mice (P<0.01 and P<0.05, respectively). H. hepaticus altered the beta diversity of cecal microbiome in both WT and FXR KO mice compared to uninfected mice (P<0.05). Significant upregulation of ß-catenin, Rela, Slc10a1, Tlr2, Nos2, Vdr, and Cyp3a11 was observed in all FXR KO mice compared to controls (P<0.05). Importantly, H. hepaticus and FXR deficiency were necessary to significantly upregulate Cyp2b10 (P<0.01). FXR deficiency was also a potent modulator of the cecal microbiota, as observed by a strong decrease in alpha diversity. A significant decrease in Firmicutes, particularly members of the order Clostridiales, was observed in FXR KO mice (P<0.05 and FDR<5%, ANOVA). While FXR deficiency strongly affects expression of genes related to immunity and bile acid metabolism, as well as the composition of the microbiome; however, its deficiency was not able to produce significant histopathological changes in the absence of H. hepaticus infection.

Gut microbiome phenotypes driven by host genetics affect arsenic metabolism.

Large individual differences in susceptibility to arsenic-induced diseases are well-documented and frequently associated with different patterns of arsenic metabolism. In this context, the role of the gut microbiome in directly metabolizing arsenic and triggering systemic responses in diverse organs raises the possibility that gut microbiome phenotypes affect the spectrum of metabolized arsenic species. However, it remains unclear how host genetics and the gut microbiome interact to affect the biotransformation of arsenic. Using an integrated approach combining 16S rRNA gene sequencing and HPLC-ICP-MS arsenic speciation, we demonstrate that IL-10 gene knockout leads to a significant taxonomic change of the gut microbiome, which in turn substantially affects arsenic metabolism.

Mast cell tumor invading the cornea in a horse.

A 3-year-old Marwari mare was presented for evaluation of an irregular, reddish mass protruding from behind the right third eyelid. The mass appeared to arise at the ventral limbal area, involved the perilimbal bulbar conjunctiva and widely extended into corneal tissue. No other ocular or systemic abnormalities were detected at the time of presentation. The mass was surgically removed by lamellar keratectomy, with defocused CO(2) laser used as adjunctive therapy to treat the surgical exposed area and its surroundings. Histopathologic evaluation showed sheets of densely packed, well-differentiated neoplastic mast cells separated by fibrovascular connective tissue. Nuclear staining for Ki-67 was performed, and an average of 370 cells were positive per 1000 counted cells. Two months postoperatively, the surgical site was filled with flat fibrovascular and pigmented tissue, while the surrounding cornea was transparent with no superficial vascularization around the fibrotic scar. Thirty-two months after treatment, no recurrence of the neoplasia was reported.

In vivo biosensing via tissue-localizable near-infrared-fluorescent single-walled carbon nanotubes.

Single-walled carbon nanotubes are particularly attractive for biomedical applications, because they exhibit a fluorescent signal in a spectral region where there is minimal interference from biological media. Although single-walled carbon nanotubes have been used as highly sensitive detectors for various compounds, their use as in vivo biomarkers requires the simultaneous optimization of various parameters, including biocompatibility, molecular recognition, high fluorescence quantum efficiency and signal transduction. Here we show that a polyethylene glycol ligated copolymer stabilizes near-infrared-fluorescent single-walled carbon nanotubes sensors in solution, enabling intravenous injection into mice and the selective detection of local nitric oxide concentration with a detection limit of 1 µM. The half-life for liver retention is 4 h, with sensors clearing the lungs within 2 h after injection, thus avoiding a dominant route of in vivo nanotoxicology. After localization within the liver, it is possible to follow the transient inflammation using nitric oxide as a marker and signalling molecule. To this end, we also report a spatial-spectral imaging algorithm to deconvolute fluorescence intensity and spatial information from measurements. Finally, we demonstrate that alginate-encapsulated single-walled carbon nanotubes can function as implantable inflammation sensors for nitric oxide detection, with no intrinsic immune reactivity or other adverse response for more than 400 days.

Gut microbiome perturbations induced by bacterial infection affect arsenic biotransformation.

Exposure to arsenic affects large human populations worldwide and has been associated with a long list of human diseases, including skin, bladder, lung, and liver cancers, diabetes, and cardiovascular disorders. In addition, there are large individual differences in susceptibility to arsenic-induced diseases, which are frequently associated with different patterns of arsenic metabolism. Several underlying mechanisms, such as genetic polymorphisms and epigenetics, have been proposed, as these factors closely impact the individuals' capacity to metabolize arsenic. In this context, the role of the gut microbiome in directly metabolizing arsenic and triggering systemic responses in diverse organs raises the possibility that perturbations of the gut microbial communities affect the spectrum of metabolized arsenic species and subsequent toxicological effects. In this study, we used an animal model with an altered gut microbiome induced by bacterial infection, 16S rRNA gene sequencing, and inductively coupled plasma mass spectrometry-based arsenic speciation to examine the effect of gut microbiome perturbations on the biotransformation of arsenic. Metagenomics sequencing revealed that bacterial infection significantly perturbed the gut microbiome composition in C57BL/6 mice, which in turn resulted in altered spectra of arsenic metabolites in urine, with inorganic arsenic species and methylated and thiolated arsenic being perturbed. These data clearly illustrated that gut microbiome phenotypes significantly affected arsenic metabolic reactions, including reduction, methylation, and thiolation. These findings improve our understanding of how infectious diseases and environmental exposure interact and may also provide novel insight regarding the gut microbiome composition as a new risk factor of individual susceptibility to environmental chemicals.

Helicobacter pylori infection does not promote hepatocellular cancer in a transgenic mouse model of hepatitis C virus pathogenesis.

Helicobacter pylori (H. pylori) and hepatitis C virus (HCV) infect millions of people and can induce cancer. We investigated if H. pylori infection promoted HCV-associated liver cancer. Helicobacter-free C3B6F1 wild-type (WT) and C3B6F1-Tg(Alb1-HCVN)35Sml (HT) male and female mice were orally inoculated with H. pylori SS1 or sterile media. Mice were euthanized at ~12 mo postinoculation and samples were collected for analyses. There were no significant differences in hepatocellular tumor promotion between WT and HT mice; however, HT female mice developed significantly larger livers with more hepatic steatosis than WT female mice. H. pylori did not colonize the liver nor promote hepatocellular tumors in WT or HT mice. In the stomach, H. pylori induced more corpus lesions in WT and HT female mice than in WT and HT male mice, respectively. The increased corpus pathology in WT and HT female mice was associated with decreased gastric H. pylori colonization, increased gastric and hepatic interferon gamma expression, and increased serum Th1 immune responses against H. pylori. HT male mice appeared to be protected from H. pylori-induced corpus lesions. Furthermore, during gastric H. pylori infection, HT male mice were protected from gastric antral lesions and hepatic steatosis relative to WT male mice and these effects were associated with increased serum TNF-α. Our findings indicate that H. pylori is a gastric pathogen that does not promote hepatocellular cancer and suggest that the HCV transgene is associated with amelioration of specific liver and gastric lesions observed during concurrent H. pylori infection in mice.

Probiotic Lactobacillus reuteri attenuates the stressor-enhanced severity of Citrobacter rodentium infection.

Stressor exposure has been shown to enhance host susceptibility and the severity of a plethora of illnesses, including gastrointestinal disease. In mice, susceptibility to Citrobacter rodentium has been shown to be dependent on host genetics as well as the composition of the intestinal microbiota, but the effects of stressor exposure on this gastrointestinal pathogen have not been elucidated fully. Previously, our lab showed that exposure to the prolonged-restraint stressor prior to a challenge with C. rodentium alters the intestinal microbiota community structure, including a reduction of beneficial genera such as Lactobacillus, which may contribute to stressor-enhanced C. rodentium-induced infectious colitis. To test the effects of stressor exposure on C. rodentium infection, we exposed resistant mice to a prolonged-restraint stressor concurrent with pathogen challenge. Exposure to prolonged restraint significantly enhanced C. rodentium-induced infectious colitis in resistant mice, as measured by increases in colonic histopathology, colonic inflammatory mediator gene production, and pathogen translocation from the colon to the spleen. It was further tested if the beneficial bacterium Lactobacillus reuteri could reduce the stressor-enhanced susceptibility to C. rodentium-enhanced infectious colitis. While L. reuteri treatment did not reduce all aspects of stressor-enhanced infectious colitis, it did significantly reduce pathogen translocation from the colon to the spleen. Taken together, these data demonstrate the deleterious effects that prolonged stressor exposure can have at the onset of a gastrointestinal infection by its ability to render a resistant mouse highly susceptible to C. rodentium. Probiotic treatment ameliorated the systemic manifestations of stress on colonic infection.

Enteropathogenic Escherichia coli prevalence in laboratory rabbits.

Rabbit-origin enteropathogenic Escherichia coli (EPEC) causes substantial diarrhea-associated morbidity and has zoonotic potential. A culture-based survey was undertaken to ascertain its prevalence. EPEC was isolated from 6/141 (4.3%) commercially-acquired laboratory rabbits. Three of these did not have diarrhea or EPEC-typical intestinal lesions; they instead had background plasmacytic intestinal inflammation. Asymptomatically infected rabbits may function as EPEC reservoirs.

Enzootic enteropathogenic Escherichia coli infection in laboratory rabbits.

Enteropathogenic Escherichia coli (EPEC) is the most important cause of persistent diarrhea in children, particularly in developing countries. Animals serve as pathogenic E. coli reservoirs, and compelling evidence for cross-species EPEC transmission exists. In this report, enzootic EPEC infection associated with up to 10.5% diarrhea-associated morbidity in a large laboratory Dutch Belted rabbit colony was investigated. These rabbits were obtained from a commercial vendor and had acute diarrhea following shipment. Fecal culture of 20 rabbits yielded 48 E. coli isolates, 83% of which were eae positive. Repetitive sequence-based PCR (REP-PCR) and serologic analysis identified a single disease-associated EPEC O145:H2 strain. In sampled rabbits, EPEC-positive culture and the presence of diarrhea were significantly associated. This strain displayed a localized adherence-like HEp-2 cell adherence pattern, as seen in diarrheic human infant EPEC isolates. Treatment was instituted with the fluoroquinolone antibiotic enrofloxacin, to which all isolates were susceptible. Preshipment parenteral enrofloxacin administration reduced diarrhea-associated morbidity 22-fold and mortality 12-fold in subsequent deliveries. This report emphasizes the zoonotic potential of animal EPEC strains and the need for virulence determinant-based screening of E. coli isolates from diarrheic animals.

17ß-estradiol and tamoxifen prevent gastric cancer by modulating leukocyte recruitment and oncogenic pathways in Helicobacter pylori-infected INS-GAS male mice.

Helicobacter pylori infection promotes male predominant gastric adenocarcinoma in humans. Estrogens reduce gastric cancer risk and previous studies showed that prophylactic 17ß-estradiol (E2) in INS-GAS mice decreases H. pylori-induced carcinogenesis. We examined the effect of E2 and tamoxifen (TAM) on H. pylori-induced gastric cancer in male and female INS-GAS mice. After confirming robust gastric pathology at 16 weeks postinfection (WPI), mice were implanted with E2, TAM, both E2 and TAM, or placebo pellets for 12 weeks. At 28 WPI, gastric histopathology, gene expression, and immune cell infiltration were evaluated and serum inflammatory cytokines measured. After treatment, no gastric cancer was observed in H. pylori-infected males receiving E2 and/or TAM, whereas 40% of infected untreated males developed gastric cancer. E2, TAM, and their combination significantly reduced gastric precancerous lesions in infected males compared with infected untreated males (P < 0.001, 0.01, and 0.01, respectively). However, TAM did not alter female pathology regardless of infection status. Differentially expressed genes from males treated with E2 or TAM (n = 363 and n = 144, Q < 0.05) associated highly with cancer and cellular movement, indicating overlapping pathways in the reduction of gastric lesions. E2 or TAM deregulated genes associated with metastasis (PLAUR and MMP10) and Wnt inhibition (FZD6 and SFRP2). Compared with controls, E2 decreased gastric mRNA (Q < 0.05) and serum levels (P < 0.05) of CXCL1, a neutrophil chemokine, leading to decreased neutrophil infiltration (P < 0.01). Prevention of H. pylori-induced gastric cancer by E2 and TAM may be mediated by estrogen signaling and is associated with decreased CXCL1, decreased neutrophil counts, and downregulation of oncogenic pathways.

Growth of the acetabular lateral cartilage in relation to congenital and developmental dysplasia of the hip. An histological study.

There are no clear explanations for the spectrum of hip dysplasia nor for the observation that in normal and dysplastic hips, final development may be unpredictable with or without treatment. Immunohistochemical and histological studies of a three month old child's acetabulae were performed. Multiple inclusions were found in the lateral ring epiphysis and in the three flanges of the triradiate cartilage. These inclusions may represent cartilage vessel systems pre-destined to form the secondary centres of ossification. Damage to the primary acetabular growth plates may occur congenitally and help to explain the spectrum of acetabular dysplasia. Damage to one or more of these centres, whether due to instability, displacement or iatrogenic injury, may cause failure of late acetabular development. Hips at risk of damage to the acetabular cartilages should be followed up longer.

Urinary bladder agenesis in an alpaca (Vicugna pacos) cria.

A 10-day-old female alpaca (Vicugna pacos) cria with a history of urinary straining and dribbling was presented for evaluation. The animal had markedly elevated blood fibrinogen (800 mg/dl), mildly elevated phosphorus (9.3 mg/dl), and minimally elevated blood urea nitrogen (38 mg/dl) concentrations. The total protein (5.0 g/dl) concentration was mildly decreased. These findings were suggestive of mild renal disease. An abdominal ultrasound revealed bilateral hydronephrosis and hydroureter, and no urinary bladder was identified. Gross postmortem examination revealed urinary bladder agenesis and bilateral hydronephrosis and hydroureter, with both ureters opening into a sinus in the caudal vagina. Histologic examination of the kidneys showed necrosuppurative pyelonephritis with pelvic dilation, and both ureters had mild lymphoplasmacytic and histiocytic inflammation.

Stressor exposure disrupts commensal microbial populations in the intestines and leads to increased colonization by Citrobacter rodentium.

The gastrointestinal tract is colonized by an enormous array of microbes that are known to have many beneficial effects on the host. Previous studies have indicated that stressor exposure can disrupt the stability of the intestinal microbiota, but the extent of these changes, as well as the effects on enteric infection, has not been well characterized. In order to examine the ability of stressors to induce changes in the gut microbiota, we exposed mice to a prolonged restraint stressor and then characterized microbial populations in the intestines using both traditional culture techniques and bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP). Exposure to the stressor led to an overgrowth of facultatively anaerobic microbiota while at the same time significantly reducing microbial richness and diversity in the ceca of stressed mice. Some of these effects could be explained by a stressor-induced reduction in the relative abundance of bacteria in the family Porphyromonadaceae. To determine whether these alterations would lead to increased pathogen colonization, stressed mice, as well as nonstressed controls, were challenged orally with the enteric murine pathogen Citrobacter rodentium. Exposure to the restraint stressor led to a significant increase in C. rodentium colonization over that in nonstressed control mice. The increased colonization was associated with increased tumor necrosis factor alpha (TNF-alpha) gene expression in colonic tissue. Together, these data demonstrate that a prolonged stressor can significantly change the composition of the intestinal microbiota and suggest that this disruption of the microbiota increases susceptibility to an enteric pathogen.