Protozoan infections Archives • Page 2 of 2 • Microbe Online

Acute diarrhea is categorized as noninflammatory (watery, nonbloody) or inflammatory (bloody). The term dysentery refers to bloody diarrhea. Bloody diarrhea caused by Shigella is often called bacillary dysentery. Other bacterial causes of dysentery are, Vibrio parahaemolyticus, Enteroinvasive E.coli (EIEC), Enterohemrorrhagic E.coli (EHEC), Campylobacter sps, and Salmonella sps. Bloody mucous containing diarrhea caused by bacterial pathogens is often accompanied by inflammatory cells (neutrophils). Other symptoms include fever, abdominal cramping, tenesmus, and pain in defecation. Amoebic dysentery (also known as amoebiasis) is caused by an invasive protozoan parasite, Entamoeba histolytica. Character Amoebic dysentery Bacillary dysentery Macroscopic Number 6-8 motions a day Over 10 motions a day Amount (Volume) Relatively copious Small amount Appearance and Amount Blood mucus, semi formed Blood mucus, mainly watery Odour Offensive (fishy odour) Odourless Colour Dark red (altered blood) Bright red (fresh blood) Reaction Acidic Alkaline Consistency Not adherent to the container Adherent to the container Microscopic RBCs In clumps Discrete, sometimes in clumps due to rouleaux formation Pus Cells Few Numerous Macrophages Few Numerous, many of them contain RBCs hence may be mistaken for E. histolytica Eosinophils Present Scarce Charcot-Leyden (C-L) crystals* Present Absent Pyknotic bodies** Present Absent Ghost Cells*** Absent Present Parasites Seen Trophozoites of E. histolytica Absent Bacteria Seen Many motile bacteria Scanty, nonmotile (Shigella is nonmotile bacteria) Culture Growth on MacConkey Agar Various intestinal flora may grow Pure growth of Shigella spp. may be seen Further notes: Charcot Leyden Crystals *Charcot-Leyden crystals are hexagonal bipyramidal structures, formed from the breakdown of eosinophils and may be seen in the stool or sputum of patients with parasitic diseases. **Pyknotic bodies are the nuclear remains of tissue cells and leukocytes, they may present in the stools of persons suffering from amoebiasis. ***Ghost cell is a swollen/enlarged epithelial cell with only cytoplasmic outline but without a nucleus. References Manson-Bahr, P. E., & Ormerod, W. E. (1971). Amoebic and bacillary dysentery and the enteric fevers. The Practitioner, 207(238), 154–163. Cook G. C. (1977). Dysentery-bacillary and amoebic. Nursing mirror and midwives journal, 144(12), 54–57. Dans, L. F., & Martínez, E. G. (2007). Amoebic dysentery. BMJ clinical evidence, 2007, 0918.