Intestinal Amebiasis & Protozoa

Unit 2: Intestinal Parasitosis by Protozoa

• Unit 2 covers intestinal parasitosis caused by protozoa
• It includes intestinal amebiasis and other intestinal protozooses

Capítulo 2. Intestinal Amebiasis

• The chapter focuses on the study of intestinal amebiasis

Hepatic Amebiasis

• Preventative measures are difficult to establish for amebic hepatic abscess
• Recommendations focus on preventing intestinal amebiasis, which precedes hepatic invasion

Treatment of Amebiasis

• 5-nitroimidazoles are the drugs of choice, acting directly on the trophozoites in the abscess wall
• Treatment duration is generally 5-10 days
• Surgical intervention to drain the abscess is rarely required
• Hepatic amebic abscess treatment is mainly chemotherapy
• Evacuating punctures and surgical drainage have specific indications
• Antiamebic therapy adjustments are made based on needs and severity
• Surgeon assistance is considered if chemotherapy is inefficient

Managing Persistent Cases

• Suspect a pyogenic abscess and culture necrotic material or start antibiotics if antiamebic therapy fails
• 5-nitroimidazoles are highly effective, curing 90% as a single medication
• Remaining cases need puncture or surgery

Metronidazole Usage

• The oldest 5-nitroimidazole, is used at 30-50 mg/kg/day orally, about 2 g daily for adults, split into three doses with meals
• Treatment lasts 5-10 days
• Intravenous metronidazole is an option when oral is unfeasible, presented at 5% in venous perfusion, with doses dependent on volume
• Dosage is 10 mg/kg for over 12s and 7.5 mg/kg for younger, administered every 8 hours for 5-10 days

Other Nitroimidazoles

• Ornidazole comes in 500 mg tablets and injectable form, using similar metronidazole doses
• Tinidazole is given at 2 g daily for adults, 50-60 mg/kg for children, single dose after meal for 3-5 days
• Secnidazole is also effective at 30 mg/kg/day for multiple days
• Chapter on intestinal amebiasis covers precautions, side effects, toxicity, and other medication details

Second-Line Treatments

• Dehydroemetine is dosed at 1 mg/kg/day for 5-10 days, although discontinued in some countries due to toxicity limitated use
• Antibiotics are not routine unless a superimposed bacteria exists or diagnostic uncertainty exists
• Non-absorbable amebicides are added to the regimen in conjunction with amebiasis to eliminate parasites from the colon and prevent returns

Surgical Procedures

• Evacuating puncture is prone to overuse, which induces secondary infections
• It remains essential when symptoms worsen with medication after 5 days and when abscesses present as large/ rupture likely
• Surgery takes place in the surgical ward under guaranteed aseptic conditions
• Surgical intervention only occurs if symptoms worsen, persist

Chronic Amebiasis/ Non-Dysenteric Amebic Colitis

• It is defined as the case in which colitis-like symptoms are present in the absence of dysentery
• Symptoms are long-lasting and may follow an acute attack
• Primarily causes abdominal pain, alterations in bowel habits which causes diarrhea, mucus in stool, rarely blood
• Effort and urge to defecate are less frequent than in acute amebiasis
• Spasmodic pain intensifies before and during bowel movements
• Bowel habit changes can reflect changes in the frequency or number of bowel movements
• Bowel changes have variable duration and intensity
• Stools are diarrheic that can contain trophozoites and sometimes cysts

Additional Symptoms of Chronic Amebiasis

• The amebic will often experience post-eating fullness, nausea, bloating, and borborygmi
• Colon and sigmoid palpation produces palpable pain during clinical examination
• Chronic phase may evolve into other forms or spontaneous healing through symptoms will still show

Acute Amebiasis/ Dysenteric Amebic Colitis

• Primary symptom: excessive intestinal evacuations lead to copious, loose stools then smaller stools with mucus and blood
• Patients require a great deal of effort to evacuate
• Stool diminishes each bowel movement until only sanguinolent mucus, known as rectal sputum, is eliminated
• Bowel evacuation prompts burning sensations which leads to cramping rectal spasms
• Tenesmus: prompts the perceived need to continue defecating in the absence of stool
• Daily bowel movements vary, usually six or more
• Fecal matter has hematophagous trophozoites
• Mucosal ulcers are discernable through endoscopy which causes pain and cramps

Complications

• Complications can arise if the patient's general condition is compromised
• Without resolution fever is absent and can indicate infection
• Hyperthermia causes general symptoms like weakness and dehydration along with rectitis

Post-Amebic Diarrheic Syndrome

• Condition where parasites are not found after treatment has concluded

Fulminant Amebic Colitis

• Exceedingly hyperacute amebiasis
• Intense abdominal pain, diarrhea, urge to purge, anorexia and emaciation lead to the infection
• Bacterial infections can occur causing higher sensitivity on physical exams

Symptoms of Hepatic Amebiasis

• While not entirely consistent, symptoms can be categorized as follows
• Rarely a magnitude of lesions can persist without symptoms
• General discomfort and low energy are prominent in hepatic lesions
• Liver's pain fluctuates in severity but is typically higher in upper right abdominal quadrant and worsens during inhaling

Fever

• Fever arises with intermittent intensity
• Can be confused with parasitical conditions

Hepatomegaly

• Enlargement will depend on the severity of the tumor
• Lungs can experience pulmonary issues due to hepatic compression

Dissemination

• Via hematogenous introduction to other organs
• Cases generally occur among general health compromised

Hepatitis

• From anatomical perspective this condition isn't recognizable
• Considered initial process, but always in transition

Diagnosis

• Hepatic abscess closely mimics wide-scale illness and produces severe pain
• Imaging occurs through eschemia, blood samples are obtained through ELISA

Diagnostic Scenarios for Differential Illnesses

• Hepatitis and tumors produce hepatic masses
• Atypical pathogens incite perihepatic ache
• Spherocytes give rise to febrile

Complications From Disease Progression

• Shock is frequently the precursor
• Metronidazole treatment with surgical interventions increased survival outcomes from 0%-40%

Additional Complications

• More advanced forms of the condition include gangrenous colitis and intestinal rupture
• Occurs with malnutrition and defensive immunologic response compromise

Amebiasis Perforation

• Rupture occurs in necrotic fulminate forms
• Perforation can slowly advance to retroperitoneum

Ameboma Manifestation

• Occurs as tangible painful mass of varying size found most frequently with the sigmoid and rectum
• The parasitic infection may be mistaken for carcinoma

Amebiasis Appendicitis

• Mimics manifestations of bacterial appendicitis
• Histological study clarifies the diagnosis

Symptomatic Diagnosis

• Many varying etiologies stem from colon
• Coprologic exams prevent full diagnosis because positivity is variable

Enhanced Diagnosis

• Can be achieved through increased collection of a stool samples
• Additional culture testing can be facilitated with better detection

Differential Diagnoses

• Intestinal amebiasis is diverse and can share traits across various medical condition
• 70% of infectious agents can now be discerned by experts

Acquired Resistance

• Individuals in at risk areas can be exposed with lesser frequency
• Trials imply development, which is dependent upon the parasite

Immune Response

• Tissue damage by amoeba invokes host immune reactions
• This is demonstrated by greater IgG levels

Positive reactions

• Can arise years following parasitic infection
• Prevents over-estimation and is a serological index

Cellular Immunity

• Infections determine lesion control
• Initial amoebic infection isn't influenced by cell mediated pathways in gut

Fecal Samples

• Must be taken at specified intervals
• Saline solutions must be used to preserve for longer examination

Microscopic Testing

• Primary use is to highlight trophozoites
• This provides analysis of amebic characteristics
• Trophozoites must be differentiated by the type of colitis presented

Other Microscopic Factors

• Stool type as a feature to find cysts
• Lugol preparation to look at trophozoite
• Hematoxylin is used study morphology
• Quists are mainly found in solid stool

Accurate Detection

• Can occur when stool exams take place over a 10-day period
• This process enables enhanced parasite recovery between 85%-95%

Diagnoses

• Lab settings must confirm presence of diarrhea
• Fecal sample collection must be done before barium use via rectum

Diagnostic Laboratory Collection Standards

• Enema use can only facilitate collection with saline
• Trophozoites can change with altered pH

Infection

• Can occur through direct exposure from the large intestines
• Infection requires lab analysis to ensure correct etiology

Stool Samples

• Stool must analyzed with lab testing
• Clinical difference in shigellosis can be made with microscopic testing

Precautionary Methods

• Can prevent negative consequences from use
• Colon cancer can present as the result

Laboratory Diagnosis

• Requires stool removal when spontaneous
• Stool sample can be taken 24 hours after release

Three Primary causes

• Are composed of giardiasis amebiasis cryptosporidiosis

Biopsies

• In colon infections amoeba can be classified with standard staining _E. histolytica only exists between amoeba form

Fecal Immunological Testing

• Modern technique is a method differentiation _Antibodies are a type protein to detect

Serological Testing

• Test can confirm reactions
• The serum creates new interactions

The Three Primary Causes of Parasitic Diarrhea

-Giardiasis, amebiasis, cryptosporidiosis are tested through lab testing