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{{Siren|Clostridium difficile infection}}  
{{Siren|Clostridium difficile infection}}  
{{Clostridium difficile}}
{{Clostridium difficile infection}}
{{CMG}}; {{AE}} {{YD}}
{{CMG}}; {{AE}} {{YD}}


==Overview==
==Overview==
''Clostridium difficile'' or CDF/cdf' is a species of [[bacteria]] of the genus ''[[Clostridium]]'' which are [[Gram-positive]], [[Anaerobic organism|anaerobic]], [[endospore|spore]]-forming rods (bacillus).<ref name=Sherris>{{cite book | author = Ryan KJ; Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | pages = pp. 322-4 | publisher = McGraw Hill | year = 2004 | id = ISBN 0-8385-8529-9 }}</ref> ''Clostridium difficile'' (C. diff) is one of the most common hospital-acquired infections, particularly in elderly hospitalized patients, and also one of the most common complications of antibiotics in hospitalized patients. Patients are rarely infected unless the normal flora of the intestinal tract has been altered by antibiotics. Up to 10% of patients hospitalized >2 days are affected.Of note, most antibiotic-associated diarrhea is not due to ''C. diff'', but is due to an osmotic type diarrhea.  The antibiotics wipe out the gastrointestinal (GI) tract’s normal flora, which usually break down unabsorbed carbohydrates. These unabsorbed carbohydrates remain in the lumen and carry with them water, resulting in diarrhea.''C. difficile'' is the most significant cause of [[pseudomembranous colitis]],<ref name=eMed1942>{{ cite web | url= http://www.emedicine.com/med/topic1942.htm#section~introduction
''Clostridium difficile'' infection is caused by the bacterium ''C. difficile'', a a [[spore|spore-forming]], [[toxin|toxin-producing]], [[obligate anaerobic]], [[gram-positive]] [[bacillus]]. The incidence of ''C. difficile'' infection is estimated to be 140 per 100,000 individuals. In USA, the majority (65%) of cases are associated with [[healthcare]] settings, and 25% of cases are associated with previous [[hospitalizations]]. The most important risk factor for the development of ''C. difficile'' infection is history of [[antibiotic]] use within the past 12 weeks. Other important risk factors include recent hospitalization (< 12 weeks), advanced age (> 65 years), [[immunodeficiency]] (primary or secondary causes), [[inflammatory bowel disease]], and exposure to colonized/infected individuals. ''C. difficile'' spores are transmitted via the [[fecal-oral route]]. Following ingestion, spores germinate to the [[Vegetative reproduction|vegetative form]] in the [[small intestine]] and eventually colonize in the [[large intestine]] in susceptible patients. ''C. difficile'' does not result in clinical manifestations in the majority of cases, whereby normal GI flora resists the growth of ''C. difficile'', and the host [[immune response]]<nowiki/>s adequately clear the infection before the development of clinical manifestations. However, in susceptible patients, ''C. difficile'' releases 2 major virulence factors: Exotoxins A and B (TcdA and TcdB), which act synergically and mediate adhesion to the [[mucosa|colonic mucosa]], luminal fluid accumulation, and development of clinical manifestations. The onset of clinical manifestations may occur within 2 hours up to several months following antibiotic administration. Patients typically develop mild/moderate [[watery diarrhea]] (possibly [[Bloody diarrhea|bloody]]) associated with colicky diffuse [[abdominal pain]], [[nausea]], [[malaise]], and low-grade [[fever]]. If left untreated, patients may develop [[colitis]] (with or without [[pseudomembrane]] formation). Approximately 3% of patients develop complications, which might be colonic ([[fulminant colitis]]) or extracolonic. The majority of patients with ''C. difficile'' infection recover without sequelae and are responsive to [[antimicrobial therapy]]. Nonetheless, ''C. difficile'' infection is associated with a high lifetime recurrence rate that ranges between 20% to 60%, and most recurrences occur a few weeks following the successful completion of antimicrobial therapy. The gold standard for the diagnosis of ''C. difficile'' infection is [[cell culture cytotoxic assay]], but it is rarely used clinically (difficult technique and time consuming). Among symptomatic patients, ''C. difficile'' infection is diagnosed either by [[enzyme immunoassay]] (ELISA) for toxins A and/or B in stools or by DNA-based tests ([[PCR]]). ''C. difficile'' infection may be classified based on the clinical severity of the disease. and the severity of the infection dictates the choice of antimicrobial therapy and the need for surgical consultation/management. Administration of oral [[metronidazole]] is recommended for patients with mild symptoms, whereas oral [[vancomycin]] is recommended for severe disease.
  | title=Pseudomembranous Colitis
  | work=eMedicine
  | date=1 July 2005
  | publisher=WebMD
  | accessdate=2007-01-11}} </ref> a severe infection of the [[colon (anatomy)|colon]], often after normal [[gut flora]] is eradicated by the use of [[antibiotic]]s.


==Diagnosis==
==Historical Perspective==
===Symptoms===
''Clostridium difficile'' was first isolated in 1935 during an experiment from [[fecal extract]]s of healthy [[neonate]]s. The association between ''C. difficile'' and antibiotic-associated pseudomembranous colitis was first made in 1978. In 2003, a resistant, [[hypervirulent strain]] of ''C. difficile'' (NAP/BI/027 strain) with increased synthesis of toxins A and B was first identified.
In adults, a [[clinical prediction rule]] found the best [[medical sign|signs]] are<ref name="pmid8644759">{{cite journal |author=Katz DA, Lynch ME, Littenberg B |title=Clinical prediction rules to optimize cytotoxin testing for Clostridium difficile in hospitalized patients with diarrhea |journal=Am. J. Med. |volume=100 |issue=5 |pages=487–95 |year=1996 |pmid=8644759 |doi=10.1016/S0002-9343(95)00016-X }}</ref> significant [[diarrhea]] ("new onset of > 3 partially formed or watery stools per 24 hour period"), exposure of antibiotics, [[abdominal pain]], foul stool odor.
 
==Pathophysiology==
Spores of ''C. difficile'' are transmitted via the fecal-oral route to the human host. Spore ingestion may be community-acquired (soil and food) or healthcare-associated (hospitals and clinics). Following ingestion, the acid-resistant spores of ''C. difficile'' are able to survive the human gastric acidity. ''C. difficile'' does not result in clinical manifestations in the majority of cases, whereby normal GI flora resists the growth of ''C. difficile'', and the host immune responses adequately clear the infection before the development of clinical manifestations. However, in susceptible patients, ''C. difficile'' releases 2 major virulence factors: Exotoxins A and B (TcdA and TcdB), which act synergically and mediate adhesion to the colonic mucosa, luminal fluid accumulation, and development of pseudomembranous colitis. These toxins are able to glycosylate Rho GTPase (involved in actin cytoskeleton) and cause the formation of abnormal G-actin (leading to characteristic rounding of cells). Additionally, they stimulate macrophage-induced cytokine production and subsequent neutrophilic infiltration to the site of inflammation, which in part contributes to the disruption of the intestinal barrier and the development of clinical manifestations associated with the infection. On gross examination, colonic pseudomembranes with yellow colored plaque formation are typical. On microscopic examination, erosions within colonic crypts or formation of mushroom-like exudates with hemorrhage and necrosis are characteristic features.


The presence of any one of these findings has a [[sensitivity (tests)|sensitivity]] of 86% and a [[specificity (tests)|specificity]] of 45%.<ref name="pmid8644759"/> In a study on hospitalized patients with a prevalence of positive cytotoxin assays of 14%, the [[positive predictive value]] was 20% and the [[negative predictive value]] was 95%.
==Causes==
''C. difficile'' infection is caused by ''Clostridium difficile'', a spore-forming, toxin-producing, oligate anaerobic, gram-positive bacillus.
==Classification==
''C. difficile'' infection may be classified based on the clinical severity of the disease. The severity of the infection dictates the choice of [[Clostridium difficile infection medical therapy|antimicrobial therapy]] and the need for surgical consultation/management. Mild disease is defined as isolated [[diarrhea]], whereas severe/complicated disease is defined as either [[delirium]], [[shock]], [[organ failure]], [[high-grade fever]], or marked [[leukocytosis]].
==Differential Diagnosis==
''Clostridium difficile'' infection must be differentiated from other diseases that cause acute inflammatory diarrhea, abdominal pain, fever, and ileus, including other causes of colitis (ischemic, collagenous, ulcerative), malabsorptive syndromes, diverticulitis, appendicitis, malignancies, drug-induced causes, and infections, such as salmonellosis, shigellosis, or gastrointestinal infections with ''Escherichia coli'' or ''Campylobacter jejuni''.
==Epidemiology and Demographics==
The incidence of ''C. difficile'' infection is estimated to be 20 per 100,000 person-years. In USA, the majority (65%) of cases are associated with healthcare settings, and 25% of cases are associated with previous hospitalizations. Although patients of all age groups may develop ''C. difficile'' infection, elderly patients > 65 years may have up to eight-fold increased risk of developing ''C. difficile'' infection compared with younger patients. Whites and female patients are more predisposed to develop ''C. difficile'' infections. Although ''C. difficile'' is abundantly reported in Europe and the United States, the infection is a global burden.
==Risk Factors==
The most important risk factor for the development of ''C. difficile'' infection is antibiotic use. Although ''C. difficile'' infection has been described with almost all antibiotics, ampicillin, amoxicillin, cephalosporins, clindamycin, and fluoroquinolones are most classically and most commonly associated with development of ''C. difficile'' infection. Other important risk factors include recent hospitalization (< 12 weeks), advanced age (>65 years), immunodeficiency (primary or secondary causes), inflammatory bowel disease, and exposure to colonized/infected individuals. The association between gastric acid suppression and ''C. difficile'' infection has not been well established.
==Natural History, Complications & Prognosis==
Following ingestion of ''C. difficile'' spores, patients are colonized with the organism. Typically, young healthy individuals with adequate immune responses are able to clear the organism without development of any clinical manifestations. But patients with risk factors, such as recent antibiotic use, recent hospitalization, advanced age, or immunodeficiency, are at an increased risk of developing persistent colonization and/or developing signs and symptoms of the infection. The onset of clinical manifestations may occur within 2 hours up to several months of antibiotic use. Patients typically develop mild/moderate watery diarrhea (possibly bloody) associated with colicky diffuse abdominal pain, nausea, malaise, and fever.  If left untreated, patients may develop colitis (with or without pseudomembrane formation). Approximately 3% of patients develop complications, which might be colonic (fulminant colitis) or extracolonic (small intestine involvement, bacteremia, skin infections, reactive arthritis, abscess formation, empyema, or death). The majority of patients with ''C. difficile'' infection recover without sequelae and are responsive to antimicrobial therapy. Nonetheless, ''C. difficile'' is associated with a high lifetime recurrence rate that ranges between 20% to 70%, most of which occur a few weeks following the successful completion of antimicrobial therapy.


==Diagnosis==
===History and Symptoms===
Clinical manifestations may range from an asymptomatic course to a severe/fatal presentation. Common symptoms include acute-onset, foul-smelling watery [[diarrhea]], crampy diffuse or lower [[abdominal pain]], low-grade [[fever]], [[malaise]], [[anorexia]], [[nausea]], and [[weight loss]]. Alarming symptoms that may be suggestive of colonic complications of ''C. difficile'' infection include worsening [[abdominal pain]] and [[diarrhea]], [[high-grade fever]], [[dry mucus membranes]], and [[peripheral edema]].
===Physical Examination===
Patients with ''C. difficile'' infection typically have low-grade [[fever]] and [[abdominal tenderness]] on physical examination. Additional signs on physical examination may be suggestive of worsening infection, complicated disease, or failure of antimicrobial therapy. Significant findings on physical examination include significant derangements in [[vital signs]], including high-grade [[fever]], [[tachycardia]], or [[hypotension]], signs of [[dehydration]], [[peripheral edema]] which might be suggestive of [[hypoalbuminemia]], or worsening [[abdominal tenderness]], [[distention]], palpable [[masses]], or [[inactive bowel sounds]], which may suggest [[toxic megacolon]], [[abscess development]], or [[ileus]].
===Laboratory Findings===
Testing is generally not necessarily for patients with formed stools (no diarrhea). The gold standard for diagnosis of ''C. difficile ''infection is cell culture cytotoxic assay, but it is rarely used clinically (difficult technique and time consuming). Among patients with diarrhea,''C. difficil''e infection is diagnosed either by [[enzyme immunoassay]] ([[ELISA]]) for toxins A and/or B in stools or by [[DNA-based test]]s ([[PCR]]) that detect bacterial toxin genes in stools. Although both ELISA and DNA-based tests may be performed sequentially, only one positive test is sufficient to diagnose ''C. difficile'' infection. Both ELISA and DNA-based tests also have a high [[negative predictive value]] > 95% among average-risk patients, and generally negative results warrants the search for alternative diagnoses. The advantage of DNA-based tests over ELISA is that it may detect the presence of [[BI/NAP1/027]] strain, which alters the management plan. However, DNA-based tests may also detect clinically irrelevant findings that may delay the diagnosis. Stool culture requires [[anaerobic]] culture and may not be available. Although not diagnostic, additional blood testing may be necessary to monitor for possible development of complications or the success/failure of antimicrobial therapy.
===Abdominal X-ray===
[[Abdominal X-ray]] may be required for patients suspected to have [[toxic megacolon]]. Signs on [[abdominal x-ray]] that may be suggestive of [[toxic megacolon]] include enlarged, dilated [[colon]] > 6-7 cm, loss of [[colonic haustration]]s, small intestinal dilation, presence of [[air-fluid level]]s, or [[submucosal edema]] with [[thumbprinting]].
===Abdominal CT Scan===
Abdominal CT scan is the imaging of choice for patients with ''C. difficile'' pseudomembranous colitis or patients with suspected complications. Abdominal CT scan findings may include marked colonic wall thickening or nodularity, irregular bowel walls, pericolonic stranding, or ascites formation.
===Other Imaging Findings===
In patients with suspected ''C. difficile'' infection and inconclusive laboratory diagnostic findings, atypical presentation, or unsuccessful antimicrobial therapy, either a sigmoidoscopy or colonoscopy is indicated. During endoscopy, multiple biopsies should be obtained for microscopic histopathological analysis. On gross examination, colonic pseudomembranes with yellow colored plaque formation are typical findings.
===Biopsy===
On microscopic examination, [[erosion]]s within [[colonic crypt]]s or formation of mushroom-like [[exudate]]s with [[hemorrhage]] and [[necrosis]] are characteristic features of ''C. difficile'' infection.
==Treatment==
==Treatment==
===Medical Therapy===
===Medical Therapy===
Many persons will also be asymptomatic and colonized with ''Clostridium difficile''. Treatment in asymptomatic patients is controversial, also leading into the debate of [[clinical surveillance]] and how it intersects with public health policy.
Treatment is generally recommended for average-risk patients who are symptomatic with positive lab findings for ''C. difficile'' infection. For patients with ''C. difficile'' [[Clostridium difficile risk factors|risk factors]], empiric therapy is recommended for symptomatic patients regardless of lab findings. Antimicrobial therapy is tailored acccording to the clinical severity of the infection. Administration of oral [[metronidazole]] is recommended for patients with mild symptoms, whereas oral [[vancomycin]] is recommended for severe disease.


It is possible that mild cases do not need treatment.<ref name="pmid17636768">Nelson R. Antibiotic treatment for Clostridium difficile-associated diarrhea in adults. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD004610. PMID 17636768</ref>
===Surgery===
 
Indications for surgery include peritoneal signs, persistent bacteremia, progressive clinical disease with organ damage (e.g. renal or pulmonary disease), or evidence on CT scan demonstrating worsening infection.
Patients should be treated as soon as possible when the diagnosis of ''Clostridium difficile'' colitis (CDC) is made to avoid frank [[sepsis]] or bowel perforation. Treatment is by stopping any antibiotics and commencing specific anticlostridial antibiotics, e.g. [[metronidazole]].
===Prevention===
There are no vaccines available for the prevention of ''C. difficile'' infection. Individuals in healthcare settings may reduce the risk of ''C. difficile'' infection by washing hands using soap and water (alcohol-based products are not effective), minimizing unnecessary use of antibiotic administration, and properly isolating infected patients with adequate post-discharge room disinfection.


==References==
==References==
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[[Category:Disease]]
[[Category:Disease]]
[[Category:Gastroenterology]]
[[Category:Gastroenterology]]
[[Category:Infectious disease]]
 
[[Category:Bacterial diseases]]
[[Category:Bacterial diseases]]



Latest revision as of 17:26, 18 September 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Yazan Daaboul, M.D.

Overview

Clostridium difficile infection is caused by the bacterium C. difficile, a a spore-forming, toxin-producing, obligate anaerobic, gram-positive bacillus. The incidence of C. difficile infection is estimated to be 140 per 100,000 individuals. In USA, the majority (65%) of cases are associated with healthcare settings, and 25% of cases are associated with previous hospitalizations. The most important risk factor for the development of C. difficile infection is history of antibiotic use within the past 12 weeks. Other important risk factors include recent hospitalization (< 12 weeks), advanced age (> 65 years), immunodeficiency (primary or secondary causes), inflammatory bowel disease, and exposure to colonized/infected individuals. C. difficile spores are transmitted via the fecal-oral route. Following ingestion, spores germinate to the vegetative form in the small intestine and eventually colonize in the large intestine in susceptible patients. C. difficile does not result in clinical manifestations in the majority of cases, whereby normal GI flora resists the growth of C. difficile, and the host immune responses adequately clear the infection before the development of clinical manifestations. However, in susceptible patients, C. difficile releases 2 major virulence factors: Exotoxins A and B (TcdA and TcdB), which act synergically and mediate adhesion to the colonic mucosa, luminal fluid accumulation, and development of clinical manifestations. The onset of clinical manifestations may occur within 2 hours up to several months following antibiotic administration. Patients typically develop mild/moderate watery diarrhea (possibly bloody) associated with colicky diffuse abdominal pain, nausea, malaise, and low-grade fever. If left untreated, patients may develop colitis (with or without pseudomembrane formation). Approximately 3% of patients develop complications, which might be colonic (fulminant colitis) or extracolonic. The majority of patients with C. difficile infection recover without sequelae and are responsive to antimicrobial therapy. Nonetheless, C. difficile infection is associated with a high lifetime recurrence rate that ranges between 20% to 60%, and most recurrences occur a few weeks following the successful completion of antimicrobial therapy. The gold standard for the diagnosis of C. difficile infection is cell culture cytotoxic assay, but it is rarely used clinically (difficult technique and time consuming). Among symptomatic patients, C. difficile infection is diagnosed either by enzyme immunoassay (ELISA) for toxins A and/or B in stools or by DNA-based tests (PCR). C. difficile infection may be classified based on the clinical severity of the disease. and the severity of the infection dictates the choice of antimicrobial therapy and the need for surgical consultation/management. Administration of oral metronidazole is recommended for patients with mild symptoms, whereas oral vancomycin is recommended for severe disease.

Historical Perspective

Clostridium difficile was first isolated in 1935 during an experiment from fecal extracts of healthy neonates. The association between C. difficile and antibiotic-associated pseudomembranous colitis was first made in 1978. In 2003, a resistant, hypervirulent strain of C. difficile (NAP/BI/027 strain) with increased synthesis of toxins A and B was first identified.

Pathophysiology

Spores of C. difficile are transmitted via the fecal-oral route to the human host. Spore ingestion may be community-acquired (soil and food) or healthcare-associated (hospitals and clinics). Following ingestion, the acid-resistant spores of C. difficile are able to survive the human gastric acidity. C. difficile does not result in clinical manifestations in the majority of cases, whereby normal GI flora resists the growth of C. difficile, and the host immune responses adequately clear the infection before the development of clinical manifestations. However, in susceptible patients, C. difficile releases 2 major virulence factors: Exotoxins A and B (TcdA and TcdB), which act synergically and mediate adhesion to the colonic mucosa, luminal fluid accumulation, and development of pseudomembranous colitis. These toxins are able to glycosylate Rho GTPase (involved in actin cytoskeleton) and cause the formation of abnormal G-actin (leading to characteristic rounding of cells). Additionally, they stimulate macrophage-induced cytokine production and subsequent neutrophilic infiltration to the site of inflammation, which in part contributes to the disruption of the intestinal barrier and the development of clinical manifestations associated with the infection. On gross examination, colonic pseudomembranes with yellow colored plaque formation are typical. On microscopic examination, erosions within colonic crypts or formation of mushroom-like exudates with hemorrhage and necrosis are characteristic features.

Causes

C. difficile infection is caused by Clostridium difficile, a spore-forming, toxin-producing, oligate anaerobic, gram-positive bacillus.

Classification

C. difficile infection may be classified based on the clinical severity of the disease. The severity of the infection dictates the choice of antimicrobial therapy and the need for surgical consultation/management. Mild disease is defined as isolated diarrhea, whereas severe/complicated disease is defined as either delirium, shock, organ failure, high-grade fever, or marked leukocytosis.

Differential Diagnosis

Clostridium difficile infection must be differentiated from other diseases that cause acute inflammatory diarrhea, abdominal pain, fever, and ileus, including other causes of colitis (ischemic, collagenous, ulcerative), malabsorptive syndromes, diverticulitis, appendicitis, malignancies, drug-induced causes, and infections, such as salmonellosis, shigellosis, or gastrointestinal infections with Escherichia coli or Campylobacter jejuni.

Epidemiology and Demographics

The incidence of C. difficile infection is estimated to be 20 per 100,000 person-years. In USA, the majority (65%) of cases are associated with healthcare settings, and 25% of cases are associated with previous hospitalizations. Although patients of all age groups may develop C. difficile infection, elderly patients > 65 years may have up to eight-fold increased risk of developing C. difficile infection compared with younger patients. Whites and female patients are more predisposed to develop C. difficile infections. Although C. difficile is abundantly reported in Europe and the United States, the infection is a global burden.

Risk Factors

The most important risk factor for the development of C. difficile infection is antibiotic use. Although C. difficile infection has been described with almost all antibiotics, ampicillin, amoxicillin, cephalosporins, clindamycin, and fluoroquinolones are most classically and most commonly associated with development of C. difficile infection. Other important risk factors include recent hospitalization (< 12 weeks), advanced age (>65 years), immunodeficiency (primary or secondary causes), inflammatory bowel disease, and exposure to colonized/infected individuals. The association between gastric acid suppression and C. difficile infection has not been well established.

Natural History, Complications & Prognosis

Following ingestion of C. difficile spores, patients are colonized with the organism. Typically, young healthy individuals with adequate immune responses are able to clear the organism without development of any clinical manifestations. But patients with risk factors, such as recent antibiotic use, recent hospitalization, advanced age, or immunodeficiency, are at an increased risk of developing persistent colonization and/or developing signs and symptoms of the infection. The onset of clinical manifestations may occur within 2 hours up to several months of antibiotic use. Patients typically develop mild/moderate watery diarrhea (possibly bloody) associated with colicky diffuse abdominal pain, nausea, malaise, and fever. If left untreated, patients may develop colitis (with or without pseudomembrane formation). Approximately 3% of patients develop complications, which might be colonic (fulminant colitis) or extracolonic (small intestine involvement, bacteremia, skin infections, reactive arthritis, abscess formation, empyema, or death). The majority of patients with C. difficile infection recover without sequelae and are responsive to antimicrobial therapy. Nonetheless, C. difficile is associated with a high lifetime recurrence rate that ranges between 20% to 70%, most of which occur a few weeks following the successful completion of antimicrobial therapy.

Diagnosis

History and Symptoms

Clinical manifestations may range from an asymptomatic course to a severe/fatal presentation. Common symptoms include acute-onset, foul-smelling watery diarrhea, crampy diffuse or lower abdominal pain, low-grade fever, malaise, anorexia, nausea, and weight loss. Alarming symptoms that may be suggestive of colonic complications of C. difficile infection include worsening abdominal pain and diarrhea, high-grade fever, dry mucus membranes, and peripheral edema.

Physical Examination

Patients with C. difficile infection typically have low-grade fever and abdominal tenderness on physical examination. Additional signs on physical examination may be suggestive of worsening infection, complicated disease, or failure of antimicrobial therapy. Significant findings on physical examination include significant derangements in vital signs, including high-grade fever, tachycardia, or hypotension, signs of dehydration, peripheral edema which might be suggestive of hypoalbuminemia, or worsening abdominal tenderness, distention, palpable masses, or inactive bowel sounds, which may suggest toxic megacolon, abscess development, or ileus.

Laboratory Findings

Testing is generally not necessarily for patients with formed stools (no diarrhea). The gold standard for diagnosis of C. difficile infection is cell culture cytotoxic assay, but it is rarely used clinically (difficult technique and time consuming). Among patients with diarrhea,C. difficile infection is diagnosed either by enzyme immunoassay (ELISA) for toxins A and/or B in stools or by DNA-based tests (PCR) that detect bacterial toxin genes in stools. Although both ELISA and DNA-based tests may be performed sequentially, only one positive test is sufficient to diagnose C. difficile infection. Both ELISA and DNA-based tests also have a high negative predictive value > 95% among average-risk patients, and generally negative results warrants the search for alternative diagnoses. The advantage of DNA-based tests over ELISA is that it may detect the presence of BI/NAP1/027 strain, which alters the management plan. However, DNA-based tests may also detect clinically irrelevant findings that may delay the diagnosis. Stool culture requires anaerobic culture and may not be available. Although not diagnostic, additional blood testing may be necessary to monitor for possible development of complications or the success/failure of antimicrobial therapy.

Abdominal X-ray

Abdominal X-ray may be required for patients suspected to have toxic megacolon. Signs on abdominal x-ray that may be suggestive of toxic megacolon include enlarged, dilated colon > 6-7 cm, loss of colonic haustrations, small intestinal dilation, presence of air-fluid levels, or submucosal edema with thumbprinting.

Abdominal CT Scan

Abdominal CT scan is the imaging of choice for patients with C. difficile pseudomembranous colitis or patients with suspected complications. Abdominal CT scan findings may include marked colonic wall thickening or nodularity, irregular bowel walls, pericolonic stranding, or ascites formation.

Other Imaging Findings

In patients with suspected C. difficile infection and inconclusive laboratory diagnostic findings, atypical presentation, or unsuccessful antimicrobial therapy, either a sigmoidoscopy or colonoscopy is indicated. During endoscopy, multiple biopsies should be obtained for microscopic histopathological analysis. On gross examination, colonic pseudomembranes with yellow colored plaque formation are typical findings.

Biopsy

On microscopic examination, erosions within colonic crypts or formation of mushroom-like exudates with hemorrhage and necrosis are characteristic features of C. difficile infection.

Treatment

Medical Therapy

Treatment is generally recommended for average-risk patients who are symptomatic with positive lab findings for C. difficile infection. For patients with C. difficile risk factors, empiric therapy is recommended for symptomatic patients regardless of lab findings. Antimicrobial therapy is tailored acccording to the clinical severity of the infection. Administration of oral metronidazole is recommended for patients with mild symptoms, whereas oral vancomycin is recommended for severe disease.

Surgery

Indications for surgery include peritoneal signs, persistent bacteremia, progressive clinical disease with organ damage (e.g. renal or pulmonary disease), or evidence on CT scan demonstrating worsening infection.

Prevention

There are no vaccines available for the prevention of C. difficile infection. Individuals in healthcare settings may reduce the risk of C. difficile infection by washing hands using soap and water (alcohol-based products are not effective), minimizing unnecessary use of antibiotic administration, and properly isolating infected patients with adequate post-discharge room disinfection.

References


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