Blastocystis species: Difference between revisions

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==Background==
==Background==
*Anaerobic protozoan parasites
*Anaerobic [[protozoa]]n [[parasites]]
*Found in the human gastrointestinal tract <ref> Tan KS. New insights on classification, identification, and clinical relevance of Blastocystis spp. Clin Microbiol Rev. 2008;21(4):639-665. doi:10.1128/CMR.00022-08 </ref>
*Found in the human gastrointestinal tract <ref> Tan KS. New insights on classification, identification, and clinical relevance of Blastocystis spp. Clin Microbiol Rev. 2008;21(4):639-665. doi:10.1128/CMR.00022-08 </ref>
*Most common eukaryotic parasites found in human stool
*Most common eukaryotic parasites found in human stool
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===Microbiology===
===Microbiology===
*Vary in size between 5 and 40 micrometers
*Vary in size between 5 and 40 micrometers
*Lacks a cell wall
*Lack a cell wall
*Has mitochondria, golgi apparatus, smooth and rough endoplasmic reticula
*Have mitochondria, golgi apparatus, smooth and rough endoplasmic reticula
*Typically reproduces by binary fission
*Typically reproduce by binary fission
*Grows in anaerobic culture conditions
*Grow in anaerobic culture conditions


==Clinical Features==
==Clinical Features==
*Symptoms that have been associated with individuals with Blastocystis species in their stool include:  
*Symptoms that have been associated with individuals with Blastocystis species in their stool include:  
**Watery diarrhea (may be acute or chronic)
**Watery [[diarrhea]] (may be acute or chronic)
**Nausea
**[[Nausea]]
**Anorexia
**Anorexia
**Fatigue
**Fatigue
**Abdominal cramping
**[[abdominal pain|Abdominal cramping]]
**Bloating
**Bloating
**Flatulence  
**Flatulence  
**Urticaria  
**[[Urticaria]]
*Generally patients are afebrile
*Generally patients are afebrile


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*Blastocystis species infection is often self-limiting and many mild cases will resolve quickly
*Blastocystis species infection is often self-limiting and many mild cases will resolve quickly
*Treatment options:
*Treatment options:
**Metronidazole (750 mg TID for 5-10 days) <ref> Nigro L, Larocca L, Massarelli L, et al. A placebo-controlled treatment trial of Blastocystis hominis infection with metronidazole. J Travel Med. 2003;10(2):128-130. doi:10.2310/7060.2003.31714 </ref>
**[[Metronidazole]] (750 mg TID for 5-10 days) <ref> Nigro L, Larocca L, Massarelli L, et al. A placebo-controlled treatment trial of Blastocystis hominis infection with metronidazole. J Travel Med. 2003;10(2):128-130. doi:10.2310/7060.2003.31714 </ref>
**Tinidazole (2 mg once)
**[[Tinidazole]] (2 mg once)
**Alternatives include: paromomycin, nitazoxanide, and trimethoprim-sulfamethoxazole  
**Alternatives include: paromomycin, nitazoxanide, and trimethoprim-sulfamethoxazole  


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*Admission or observation should be considered for patients who are severely dehydrated or have significant electrolyte derangements
*Admission or observation should be considered for patients who are severely dehydrated or have significant electrolyte derangements


==See Also==


==External Links==


==References==
==References==
<references/>
<references/>
[[category:ID]]

Latest revision as of 04:20, 28 December 2020

Background

  • Anaerobic protozoan parasites
  • Found in the human gastrointestinal tract [1]
  • Most common eukaryotic parasites found in human stool
  • Controversial if they are a commensal organism or a pathogen

Epidemiology

  • Have been found worldwide
  • Reside in the cecum and colon of both children in adults
  • Have also been found in various animals (including pigs, monkeys, rodents, and poultry)
  • Prevalence is geographically variable, but generally higher in developing countries

Transmission

  • Mode of transmission is not fully understood, but though to be fecal-oral [2]

Microbiology

  • Vary in size between 5 and 40 micrometers
  • Lack a cell wall
  • Have mitochondria, golgi apparatus, smooth and rough endoplasmic reticula
  • Typically reproduce by binary fission
  • Grow in anaerobic culture conditions

Clinical Features

  • Symptoms that have been associated with individuals with Blastocystis species in their stool include:
  • Generally patients are afebrile

Differential Diagnosis

Acute diarrhea

Infectious

Noninfectious

Watery Diarrhea

Traveler's Diarrhea

Evaluation

  • Stool examination via light microscopy of stained smears or wet mounts
  • Stool culture [4]
  • ELISA targeted at serum antibodies to Blastocystis species [5]
  • PCR [6]
  • Fecal leukocytes are usually absent


Management

Asymptomatic

  • Do not require therapy

Symptomatic

  • Alternative diagnoses should be considered and excluded (e.g. alternative pathogen, noninfectious cause of symptoms)
  • Initiation of treatment in symptomatic patients is controversial
  • Blastocystis species infection is often self-limiting and many mild cases will resolve quickly
  • Treatment options:
    • Metronidazole (750 mg TID for 5-10 days) [7]
    • Tinidazole (2 mg once)
    • Alternatives include: paromomycin, nitazoxanide, and trimethoprim-sulfamethoxazole

Disposition

  • Most patients can be managed as an outpatient
  • Admission or observation should be considered for patients who are severely dehydrated or have significant electrolyte derangements

See Also

External Links

References

  1. ↑ Tan KS. New insights on classification, identification, and clinical relevance of Blastocystis spp. Clin Microbiol Rev. 2008;21(4):639-665. doi:10.1128/CMR.00022-08
  2. ↑ Blastocystis hominis: commensal or pathogen? Lancet. 1991 Mar 2;337(8740):521-2. PMID: 1671894.
  3. ↑ Marx et al. “Cholera and Gastroenteritis caused by Noncholera Vibrio Species”. Rosen’s Emergency Medicine 8th edition vol 1 pg 1245-1246.
  4. ↑ Suresh K, Smith H. Comparison of methods for detecting Blastocystis hominis. Eur J Clin Microbiol Infect Dis. 2004;23(6):509-511. doi:10.1007/s10096-004-1123-7
  5. ↑ Zierdt CH, Zierdt WS, Nagy B. Enzyme-linked immunosorbent assay for detection of serum antibody to Blastocystis hominis in symptomatic infections. J Parasitol. 1995;81(1):127-129.
  6. ↑ Jones MS 2nd, Ganac RD, Hiser G, Hudson NR, Le A, Whipps CM. Detection of Blastocystis from stool samples using real-time PCR. Parasitol Res. 2008;103(3):551-557. doi:10.1007/s00436-008-1006-4
  7. ↑ Nigro L, Larocca L, Massarelli L, et al. A placebo-controlled treatment trial of Blastocystis hominis infection with metronidazole. J Travel Med. 2003;10(2):128-130. doi:10.2310/7060.2003.31714
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