Why has my patient with Clostridium difficile diarrhea developed Klebsiella bacteremia?

Although there are many potential sources for Klebsiella sp. bacteremia, C. difficile infection (CDI) itself may be associated with GI translocation of enteric organisms.

A retrospective study of over 1300 patients found an incidence of 1.8% for CDI-associated bacteremia. E. coli, Klebsiella sp. , or Enterococcus sp. accounted for 72% of cases. History of malignancy, neutropenia (at the time of CDAD), and younger age (mean 59 y) were among the risk factors.1 Another study reported over 20 cases of bacteremia caused by C. difficile plus other bacteria often of enteric origin such the aforementioned organisms, Bacteroides sp, Candida sp, and Enterobacter sp.2

CDI is thought to predispose to bacterial translocation through the GI tract by alteration of mucosal indigenous microflora, overgrowth of certain pathogens, and presence of inflammation in the mucosa.3 Interestingly, C. difficile toxin A or B may play an active role in the bacterial adherence and penetration of the intestinal epithelial barrier.4  

Bonus pearl: Did you know that C. difficile may be found in the normal intestinal flora of 3% of healthy adults, 15-30% of hospitalized patients, and up to 50% of neonates? Why neonates seem immune to CDI is another fascinating story!



  1. Censullo A, Grein J, Madhusudhan M, et al. Bacteremia associated with Clostridium difficile colitis: incidence, risk factors, and outcomes. Open Forum Infectious Diseases, Volume 2, Issue suppl_1, 1 December 2015, 943, https://doi.org/10.1093/ofid/ofv133.659 https://academic.oup.com/ofid/article/2/suppl_1/943/2635179
  2. Kazanji N, Gjeorgjievski M, Yadav S, et al. Monomicrobial vs polymicrobial Clostridum difficile bacteremia: A case report and review of the literature. Am J Med 2015;128:e19-e26. https://www.amjmed.com/article/S0002-9343(15)00458-1/abstract
  3. Naaber P, Mikelsaar RH, Salminen S, et al. Bacterial translocation, intestinal microflora and morphological changes of intestinal mucosa in experimental models of Clostridium difficile infection. J Med Microbiol 1998; 47: 591-8. https://www.ncbi.nlm.nih.gov/pubmed/9839563 
  4. Clostridium difficile toxins may augment bacterial penetration of intestinal epithelium. Arch Surg 1999;134: 1235-1242. https://jamanetwork.com/journals/jamasurgery/fullarticle/390434
Why has my patient with Clostridium difficile diarrhea developed Klebsiella bacteremia?

Can Salmonella enterocolitis predispose to inflammatory bowel disease?

Yes, enteric pathogens such as Salmonella can predispose patients to inflammatory bowel disease (IBD) through several potential mechanisms: 1

  • Causing permanent changes in the intestinal microbiota
  • Altering the epithelial barrier in the gut
  • Altering the interaction between the body’s immune system and the intestines

More specifically, Salmonella utilizes oxidized endogenous sulfur compounds released during acute intestinal inflammation to outgrow the fermentative microbiota of the colon.2  In addition, the neutrophil response to Salmonella infection can alter the constituent microbiome.3 Salmonella also modifies the tight junctions in the intestinal epithelium as it invades, thus activating the immune system (particularly toll-like-receptors), and creating a pro-inflammatory state with structural loss of the intestinal mucosa. 4 Lastly, Salmonella promotes cytokine release and neutrophil migration through pathogen recognition receptors, leaving the intestine in a pro-inflammatory state even following resolution of the infection. 1

Keep in mind that initial Salmonella infection may also mimic IBD, as it causes diffuse lesions in the colon similar to ulcerative colitis, and may cause ileitis in some patients. Stool cultures and biopsies of the colonic mucosa should help differentiate IBD from Salmonella infection. 5



  1. Schultz BM, Paduro CA, Salazar GA, et al. A potential role of Salmonella infection in the onset of inflammatory bowel diseases. Front Immunol 2017;8:191. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5329042/pdf/fimmu-08-00191.pdf
  2. Winter SE, Baumler AJ. A breathtaking feat: to compete with the gut microbiota, Salmonella drives its host to provide a respiratory electron acceptor. Gut Microbes 2011;2:58-60. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3225798/pdf/gmic0201_0058.pdf
  3. Gill N, Ferreira RB, Antunes LC, et al. Neutrophil elastase alters the murine gut microbiota resulting in enhanced Salmonella colonization. PLoS ONE 2012;7:e49646. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0049646
  4. Bueno SM, Riquelme S, Riedel CA, et al. Mechanisms used by virulent Salmonella to impair dendritic cell function and evade adaptive immunity. Immunology 2012;137:28-36. https://www.ncbi.nlm.nih.gov/pubmed/22703384
  5. De Hertogh G, Geboes K. Crohn’s disease and infections: a complex relationship. MedGenMed 2004;6:14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1435589







Contributed by Yasmin Islam MD, Mass General Hospital, Boston, MA.

Can Salmonella enterocolitis predispose to inflammatory bowel disease?

My patient with ulcerative colitis has had colectomy. Can she still get C. difficile infection?

Yes! Although a common cause of colitis, an increasing number of reports in the literature suggest C. difficile can cause enteritis as well.Antibiotic use is a major risk factor in most reports, with nearly one-half of the cases reported in patients with inflammatory bowel disease, many post-colectomy. 1-3

Mortality of C. difficile enteritis based on the first 83 cases in the literature appears to be 23%,1 but as high as 60%-83% depending on the report!2 Its diagnosis post-colectomy requires a high index of suspicion, as patients may not complain of “diarrhea” with chronically loose stools in the ileostomy bag.  Be particularly on the lookout for C. difficile enteritis in these patients when there is increased stool output, fever, hypotension, and/or leukocytosis2, and when in doubt, send a stool specimen from the ileostomy bag for C. difficile testing.

Although the pathophysiology of C. difficile enteritis is not fully understood, few observations are particularly intriguing: 

  • Small bowel mucosa may be colonized by C. difficile in about 3% of the population, potentially serving as a reservoir.2
  • Patients with ileostomy may develop a metaplasia of the terminal end mimicking colonic environment.4  
  • Exposure of rabbit ileum to C. difficile toxin A also causes significant epithelial necrosis with destruction of villi and neutrophil infiltration.5



  1. Dineen SP, Bailey SH, Pham TH, et al. Clostridium difficile enteritis: a report of two cases and systematic literature review. World J Gastrointest Surg 2013;5:37-42. https://www.wjgnet.com/1948-9366/full/v5/i3/37.htm
  2. Boland E, Thompson JS. Fulminant Clostridium difficile enteritis after proctocolectomy and ileal pouch-anal anastomosis. Gastroenterology Research and Practice 2008; 2008: Article ID 985658. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633454/pdf/GRP2008-985658.pdf
  3. Freiler JF, Durning SJ, Ender PT. Clostridium difficile small bowel enteritis occurring after total colectomy. Clin Infect Dis 2001;33:1429-31. https://pdfs.semanticscholar.org/333b/d84978cfc4ac8fd21a15bc8fd26ff3160387.pdf
  4. Apel R, Cohen Z, Andrews CW, et al. Prospective evaluation of early morphological changes in pelvic ileal pouches. Gastroenterology 1994;107:435-43. http://www.gastrojournal.org/article/0016-5085(94)90169-4/pdf
  5. Triadafilopoulos G, Pothoulakis C, Obrien MJ, et al. Differential effects of Clostridium difficile toxins A and B on rabbit ileum. Gastroenterology 1987;93:273-279. https://www.ncbi.nlm.nih.gov/pubmed/3596162
My patient with ulcerative colitis has had colectomy. Can she still get C. difficile infection?

What complications should I look for in my hospitalized patient suspected of having check-point inhibitor toxicity?

Targeting the host immune system via monoclonal antibodies known as checkpoint inhibitors (CPIs) is an exciting new strategy aimed at interfering with the ability of cancer cells to evade the patient’s existing antitumor immune response. CPIs have been shown to be effective in a wide variety of cancers and are likely to be the next major breakthrough for solid tumors1-3. Unfortunately, serious—at times fatal— immune-related Adverse Events (irAEs) have also been associated with their use4,5.

IrAEs occur in the majority of patients treated with nivolumab (a programmed death 1 [PD-1] CPI] or ipilimumab (a cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4] CPI)1. The severity of irAEs may range from mild (grade 1) to very severe (grade 4). Grading system categories discussed in more detail at link below:


Although fatigue, diarrhea, pruritis, rash and nausea are not uncommon, more severe grade (3 or 4) irAEs may also occur (Figure). The most frequent grade 3 or 4 irAEs are diarrhea and colitis; elevated ALT or AST are also reported, particularly when CPIs are used in combination. Hypophysitis, thyroiditis, adrenal insufficiency, pneumonitis, enteritis sparing the colon with small bowel obstruction, and hematologic and neurologic toxicities may also occur.

Generally, skin and GI toxicities appear first, within a few weeks of therapy, followed by hepatitis and endocrinopathies which usually present between weeks 12 and 245. High suspicion and early diagnosis is key to successful management of irAEs.

Figure. Selected irAEs associated with nivolumab and ipilimumab (adapted from reference 1).



  1. Larkin J, Chiarion-Sileni V, Gonzalez R, et al. Combined nivolumab and ipilimumab or monotherapy in untreated melanoma. N Engl J Med. 2015;373:23-34.
  2. Borghaei H, Paz-Ares L, Horn L, et al. Nivolumab versus docetaxel in advanced nonsquamous non-small-cell lung cancer. N Engl J Med. 2015;373:1627-1639.
  3. Brahmer J, Reckamp KL, Baas P, et al. Nivolumab versus docetaxel in advanced squamous-cell non-small-cell lung cancer. N Engl J Med 2015; 373:123-135.
  4. Weber JS, Yang JC, Atkins MB, Disis ML. Toxicities of immunotherapy for the practitioner. J Clin Oncol 2015;33:2092-2099.
  5. Weber JS. Practical management of immune-related adverse events from immune checkpoint protein antibodies for the oncologist. Am Soc Clin Oncol Educ Book. 2012:174-177.

Contributed by Kerry Reynolds, MD, Mass General Hospital, Boston.





What complications should I look for in my hospitalized patient suspected of having check-point inhibitor toxicity?

Is oral vancomycin prophylaxis (OVP) effective in preventing recurrent Clostridium difficile infection (CDI) in patients requiring systemic antimicrobial therapy (SAT)?

Although OVP is often administered to patients with history of CDI who require SAT, evidence to support this practice has been lacking until recently.

In a 2016 retrospective study of 203 patients with prior history of CDI, those who received OVP (125 mg or 250 mg 2x/daily) during the course of their SAT and for up to 1 week thereafter were significantly less likely to have a recurrence than the non-OVP group (4.2% vs 26.6%, respectively, O.R. 0.12 [C.I. 0.04-0.4]) (1). In this study, the mean interval between prior CDI and initiation of prophylaxis was 6.1 months (1-21 months), and the mean duration of prophylaxis following discontinuation of SAT was 1 day (0-6 days). Similar results have been reported by others (2,3).

Despite their retrospective nature, these studies lend support to the use of OVP in reducing the risk of recurrent CDI in patients who require SAT. It is unclear how long OVP should be continued after SAT is completed, if at all, but common practice is 1-2 weeks.

A randomized-controlled study comparing OVP 125 mg daily for the duration of SAT plus 5 days vs placebo appears to be on the way (4)!


  1. Van Hise NW, Bryant AM, Hennessey EK, Crannage AJ, Khoury JA, Manian FA. Efficacy of oral vancomycin in preventing recurrent Clostridium difficile infection in patients treated with systemic antimicrobial agents. Clin Infect Dis 2016; Advance Access published June 17, 2016. Doi.10.1093/cid/ciw401.
  2. Carignan A, Sebastien Poulin, Martin P, et al. Efficacy of secondary prophylaxis with vancomycin for preventing recurrent Clostridium difficile infections. Am J Gastroenterol 2016;111: 1834-40. https://www.ncbi.nlm.nih.gov/pubmed/27619835
  3. Granetsky A, Han JH, Hughes ME, et al. Oral vancomycin is highly effective in preventing Clostridium difficile infection in allogeneic hematopoietic stem cell transplant recipients. Blood 2016;128:2225; http://www.bloodjournal.org/content/128/22/2225?sso-checked=true
  4. https://clinicaltrials.gov/ct2/show/NCT03462459

Disclosure: The author of this post was also a co-investigator of one of the studies cited (ref. 1).

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Is oral vancomycin prophylaxis (OVP) effective in preventing recurrent Clostridium difficile infection (CDI) in patients requiring systemic antimicrobial therapy (SAT)?

Are GI symptoms such as nausea, vomiting, and diarrhea common in patients with influenza?

Typically, GI symptoms are more prominent in children with influenza than adults but during the H1N1 epidemic in 2009 (which has subsequently become endemic), up to 26% of hospitalized adults with H1N1 infection had abdominal pain or vomiting and up to 25% had diarrhea (1).  In fact, H1N1 virus has been isolated from stool of adult hospitalized patients (2).

Interestingly, the mechanism involved in influenza-mediated intestinal injury may have less to do with direct invasion of the intestinal mucosa by the virus and more to do with immune mediated changes  related to alterations in the intestinal microbiota induced by influenza virus infection itself (3)!  Who would have thought?



  1. Writing Committee of the WHO Consultation on Clinical Aspects of Pandemic (H1N1) 2009 influenza. Clinical aspects of pandemic 2009 influenza A (H1N1) virus infection. N Engl J Med 2010;362:1708-19.
  2. Yoo SJ, Moon SJ, Kuak E-Y, et al. Frequent detection of pandemic (H1N1) 2009 virus in stools of hospitalized patients. J Clin Microbiol 2010; 48:2314-2315.
  3. Wang J, Li F, Wei H, et al. Respiratory influenza virus infection induces intestinal immune injury via microbiota mediated Th17 cell-dependent inflammation. J Exp Med 2014;211:2397-2410.
Are GI symptoms such as nausea, vomiting, and diarrhea common in patients with influenza?