Bacillary dysentery, also known as shigellosis, is an acute infectious disease of the intestines characterized by the passage of blood-stained, mucoid stool. It is important to note that this is a localized infection of the bowel wall and does not spread systemically throughout the body. A defining feature that distinguishes bacillary dysentery from other bacterial diarrheas is the presence of blood in the stool, which results from the invasion of the Shigella bacteria into the intestinal mucosa.

Causative Agent

Shigellosis is caused by bacteria belonging to the genus Shigella. There are four main species that cause disease in humans:

• Shigella flexneri

• Shigella sonnei

• Shigella dysenteriae

• Shigella boydii

Of these, Shigella dysenteriae is considered the most virulent and produces the most severe form of the disease. These bacteria are strictly human pathogens, meaning they do not infect animals; there is no animal reservoir.

Shigella organisms are non-motile, gram-negative bacilli that reside in the gastrointestinal tract (GIT). They cause disease by invading and destroying the cells lining the colon (colonic mucosa). This process is facilitated by the production of potent exotoxins.

Sources of Infection

The primary sources of Shigella infection are:

1. Symptomatic Patients: Individuals who are actively experiencing the symptoms of shigellosis and shedding the bacteria in their stool.

2. Carriers: Individuals who harbor the Shigella bacteria in their intestines but do not exhibit any symptoms. They can still transmit the infection to others.

Infective Dose

The infective dose of Shigella is remarkably low. As few as 10 to 100 viable Shigella organisms can be sufficient to cause dysentery. While other species may require a larger dose (around 10,000 organisms), the low infective dose of Shigella contributes to its ease of transmission.

Incidence

Shigellosis can affect individuals of all age groups. However, it is particularly prevalent in areas with poor sanitation and hygiene practices. The disease is more common in tropical countries and less developed nations where access to clean water and proper sanitation facilities may be limited.

Incubation Period

The incubation period for shigellosis, which is the time between exposure to the bacteria and the onset of symptoms, typically ranges from 1 to 3 days. In some cases, it may extend up to 7 days.

Pathology: How Shigella Causes Disease

All Shigella species possess the ability to invade and destroy the epithelial cells that line the large intestine. They achieve this through the production of exotoxins, which have multiple harmful effects:

1. Enterotoxins: These toxins exert a secretory effect on the intestinal lining, similar to the mechanism of cholera toxin. This leads to the excessive secretion of fluids and electrolytes into the intestinal lumen, resulting in watery (secretory) diarrhea.

2. Cytotoxin: This potent toxin binds to the surface of intestinal cells and is then transported inside. Once inside the cells, it inhibits protein synthesis, a crucial cellular process. This disruption leads to cell death and necrosis (tissue damage), which is a key factor in the development of dysentery (bloody diarrhea).

3. Neurotoxin: While the exact role of neurotoxin is not fully understood, it is believed to be responsible for the neurological complications that are sometimes observed in children with shigellosis. These complications are generally not seen in adults.

Transmission Routes: The Oro-fecal Route

Shigella bacteria are primarily transmitted through the oro-fecal route, meaning they are spread from the feces of an infected person to the mouth of another person. The main transmission routes include:

1. Person-to-Person Contact: Direct contact, particularly finger-to-mouth transmission, is the most significant means of spreading shigellosis. This is especially common among household members, where close contact and potentially inadequate hygiene practices can facilitate transmission. The infection can also spread through ano-oral sexual contact.

2. Water-borne Transmission: Contamination of water supplies with sewage or excreta containing Shigella bacteria can lead to outbreaks of shigellosis in communities. This is a major concern in areas with inadequate water treatment and sanitation systems.

3. Food-borne Transmission: Contaminated food and milk products are significant sources of Shigella infection, particularly in institutional settings like hospitals and communities. Shigella bacteria can survive in various food items for up to 30 days under favorable conditions, making proper food handling and storage crucial.

4. Flies as Vectors: Flies can act as mechanical vectors, transmitting Shigella bacteria from contaminated feces to food or utensils. This occurs when flies land on dysenteric stool and then subsequently land on food or surfaces that come into contact with food.

Predisposing Factors

Several factors can increase the risk of Shigella infection and contribute to its spread:

1. Defective Sanitation: Poor refuse disposal practices create breeding grounds for flies and contribute to the contamination of the environment with Shigella bacteria.

2. Bad Hygienic Practices: Inadequate excreta disposal, poor hand hygiene, dirty skin and clothes, and improper cleaning of the anal area after defecation all facilitate the transmission of Shigella.

3. Heavy Environmental Infestation with Flies: High fly populations increase the likelihood of mechanical transmission of Shigella from contaminated sources to food and surfaces.

4. Wet Environment with Stagnating Water: These conditions promote the survival and proliferation of Shigella bacteria in the environment.

Signs and Symptoms

The severity of shigellosis symptoms can vary widely depending on several factors, including the specific Shigella species involved, the infective dose (number of bacteria ingested), and the amount of toxin produced by the bacteria.

1. Mild Type (Watery Diarrhea):

   • Gradual Onset: Symptoms develop gradually over time.

   • Tenesmus: A prominent symptom is tenesmus, which is a painful and often ineffectual straining to defecate.

   • Watery Stool: Initially, the stool is watery.

   • Duration: The symptoms typically last for a few days, often accompanied by abdominal discomfort.

2. Moderate Type:

   • Abrupt Onset: Symptoms appear suddenly and intensely.

   • Abdominal Pain: Severe abdominal pain is a common feature.

   • Nausea and Vomiting: Patients often experience nausea and vomiting.

   • Blood-stained Mucoid Stool: The hallmark of dysentery is the passage of stool that contains both blood and mucus.

   • Gripping and Tenesmus: Intense gripping abdominal pain and severe tenesmus (straining) are common.

   • Dysuria: Painful or difficult urination may occur.

   • Fever and Rigor: High fever accompanied by chills (rigor) is often present.

   • Appearance: The patient’s face may appear pinched, and they may have an anxious look.

   • Delirium and Confusion: In some cases, patients may become delirious and confused.

   • Marked Thirst: Dehydration can lead to intense thirst.

3. Fulminating Type (Very Severe):

   • Abrupt Onset: Similar to the moderate type, symptoms begin suddenly and are very intense.

   • Frequent Watery Diarrhea: Patients may experience very frequent watery diarrhea, passing stool as often as 10 to 20 times in 24 hours. The stool quickly becomes bloody and mucoid (muco-purulent).

   • Necrotic Sloughs: In severe cases, pieces of dead intestinal tissue (necrotic sloughs) may be passed in the stool.

   • Severe Abdominal Cramps: Intense and debilitating abdominal cramps are characteristic.

   • Tenesmus: Severe tenesmus (straining) is present.

   • Profound Prostration: Due to significant fluid loss, patients can become extremely weak and exhausted (prostration).

   • Toxemia: The absorption of bacterial toxins into the bloodstream can lead to toxemia, a serious condition.

   • Appearance: The patient’s cheeks may be flushed, their expression anxious, and their pulse rapid. The tongue may be coated yellow or appear dry, furred, and brown.

   • Marked Dehydration: Severe dehydration is a major concern, characterized by oliguria (reduced urine output), dry and shriveled skin, collapsed veins, and low blood pressure.

   • Albuminuria: The urine may contain albumin, a protein, indicating kidney involvement.

   • Restlessness: Patients are often restless and agitated.

   • Uremic Coma and Death: In the most severe cases, patients may lapse into a uremic coma (due to kidney failure) and die.

   • Perforation and Peritonitis: Although rare, perforation of the intestinal wall and subsequent peritonitis (inflammation of the abdominal lining) can occur. This may be indicated by abdominal distension and hiccups.

Other Clinical Features:

• Bloody Diarrhea: Frequent, watery diarrhea often containing visible blood and mucus.

• Abdominal Cramps: Intense, cramping pain in the abdominal region.

• Fever: High fever, often accompanied by chills.

• Tenesmus: A persistent feeling of incomplete bowel emptying, with frequent straining and an urgent need to defecate, even when the bowels are empty.

• Nausea and Vomiting: These symptoms can occur, particularly in more severe cases.

• Headache: General malaise and weakness are common.

• Dehydration: Significant fluid loss through diarrhea can lead to dehydration, especially in young children and the elderly. Signs of dehydration include dry mouth, decreased urine output, sunken eyes, and lethargy.

• Electrolyte Imbalance: Diarrhea can cause a significant loss of electrolytes (such as sodium, potassium, and chloride), leading to imbalances that can be life-threatening if not corrected.

• Rectal Prolapse: In severe cases, particularly in children, the rectum (the final part of the large intestine) can protrude from the anus due to excessive straining during defecation.

• Flatulence: Increased gas production in the intestines, leading to bloating and discomfort.

Diagnosis/Investigations

Several diagnostic tests can be used to confirm a diagnosis of shigellosis:

1. Stool Culture: This is the most definitive diagnostic test. Stool samples are cultured in a laboratory to identify the specific Shigella species present. This helps determine the appropriate antibiotic treatment.

2. Stool Analysis and Appearance/Rectal Swab: The appearance of the stool (bloody and mucoid) can be suggestive of shigellosis. A rectal swab can also be collected for analysis.

3. Microscopic Examination: Examining the stool under a microscope may reveal the presence of red blood cells (indicating bleeding in the intestines), white blood cells (indicating inflammation), and bacteria.

4. Serological Tests: These tests detect antibodies to Shigella bacteria in the blood. While not as specific as stool culture, they can be helpful in some cases.

Differential Diagnosis

It is important to differentiate shigellosis from other conditions that can cause similar symptoms:

• Cholera: Although cholera can cause severe watery diarrhea, it is usually more profuse than in shigellosis, and the stool typically does not contain blood (rice water stool).

• Acute Diarrhea from Food Poisoning: Food poisoning caused by other bacteria (e.g., Salmonella, Staphylococcus) or toxins can cause diarrhea, but the presence of blood in the stool is less common.

• Amoebiasis: This intestinal infection caused by the protozoan parasite Entamoeba histolytica can also cause bloody diarrhea but is typically more chronic.

• Ulcerative Colitis: This is a chronic inflammatory bowel disease that can cause bloody diarrhea, but it usually has a more gradual onset and a longer duration than shigellosis.

• Schistosomiasis from Schistosoma mansoni: This parasitic worm infection can cause intestinal symptoms, including bloody diarrhea, but it is usually associated with exposure to contaminated freshwater.

• Carcinoma of the Colon and Rectum: Cancer of the colon or rectum can cause changes in bowel habits, including blood in the stool, but it typically presents with other symptoms and a more prolonged course.

Management

The primary goals of managing shigellosis are to:

1. Prevent the Spread of Infection: Implementing appropriate infection control measures is crucial to prevent further transmission.

2. Preserve and Save the Patient’s Life: Prioritizing life support measures, particularly in severe cases, is essential.

3. Support Patient Recovery (Nursing Care): Providing comprehensive supportive care to aid in the patient’s recovery.

4. Eliminate the Offending Bacteria (Treatment): Administering appropriate antibiotics to eradicate the Shigella infection.

The specific management approach depends on the severity of the condition. Severe cases of shigellosis, especially those caused by Shigella dysenteriae, are considered medical emergencies and require prompt and aggressive treatment.

Severe Type of Dysentery (Medical Emergency)

First Aid Treatment:

1. Initial Assessment: The patient is received at the healthcare facility, and a rapid assessment is performed, focusing on the airway, breathing, and circulation (ABCs).

2. Dehydration and Anemia: Signs and symptoms of dehydration (e.g., dry mucous membranes, sunken eyes, reduced skin turgor) and anemia (e.g., pallor, weakness) are assessed, and appropriate actions are taken.

3. Brief History and Observations: A brief history is taken, including the onset and duration of symptoms, stool characteristics, and any associated symptoms. Observations are made regarding the patient’s general condition, level of consciousness, and vital signs.

4. Pulse Check: The pulse is checked for rate, rhythm, and volume.

5. Doctor Notification: A doctor is called immediately, and the patient is reviewed promptly.

6. Intravenous (IV) Line: An intravenous line is established to provide fluids and medications.

7. Fluid Resuscitation: Fluids such as glucose 50% (30 to 50 ml bolus), normal saline, or Ringer’s lactate (500 to 1000 ml) are administered intravenously to control blood pressure, correct electrolyte imbalances, and restore hydration.

8. Patient Reassurance: The patient and their attendant are reassured about the treatment plan, the need for hospital transfer (if necessary), and the expected course of the condition.

9. Hospital Referral: The patient is referred to the hospital promptly for further management.

Ward Management (Medical Emergency):

1. Detailed Assessment: Upon arrival at the hospital, the patient is received, and a more detailed assessment is performed, taking into account the information provided in the referral report from the initial healthcare facility.

2. Isolation: The patient is admitted to an isolation room, if available, to prevent the spread of infection. If isolation is not possible, strict barrier nursing techniques and high-level infection control measures are implemented.

3. Disinfection: Stool and vomitus are carefully disinfected using a 1% sodium hypochlorite solution or other appropriate disinfectants.

4. Dedicated Equipment: Strict use of equipment and utensils is enforced, ensuring that they are used only for that particular patient.

5. Continued IV Fluids: Intravenous fluids are continued as per the doctor’s orders to maintain hydration and electrolyte balance.

6. Frequent Monitoring: The patient is monitored closely, typically every 4 hours, for vital signs (including temperature, pulse, respiration, and blood pressure), signs and symptoms of dehydration, and signs and symptoms of anemia.

7. Immediate Investigations: The following investigations are conducted promptly:

   • Hemoglobin, Grouping, and Cross-matching: To assess the need for a blood transfusion if the patient is anemic.

   • Stool for Analysis: To identify the specific Shigella species causing the infection and to guide antibiotic therapy.

   • Serum Electrolytes: To assess electrolyte balance (sodium, potassium, chloride) and to guide fluid and electrolyte replacement.

   • Rectal Swabs: For bacterial culture to confirm the diagnosis and determine antibiotic susceptibility.

   • Full Blood Count (FBC) and Erythrocyte Sedimentation Rate (ESR): To assess the overall health status of the patient and to monitor the inflammatory response.

Continuous Care in the Ward:

1. Patient’s Personal and Environmental Hygiene: Strict attention is paid to the patient’s personal hygiene (e.g., bathing, perineal care) and the cleanliness of the environment to prevent the spread of infection. This is similar to the management of cholera or typhoid fever.

2. Feeding: During the acute stages of the illness, a fluid diet is provided to maintain hydration and minimize bowel irritation. As the stool becomes more formed and solid, the diet is gradually advanced to a soft, balanced, non-irritating, non-spiced, low-residue diet. Food hygiene is of paramount importance throughout the patient’s stay.

3. Treatment:

   • Antibiotics: Antibiotics are the mainstay of treatment for shigellosis. Common choices include:

     • Nalidixic acid: 1 mg every 6 hours for 5 days.

     • Ciprofloxacin: 1 mg stat (immediately).

   • Pain Killers: Pain relief medication may be given, such as:

     • Paracetamol: Suitable for children.

     • Bactrim: 24mg/kg for children.

4. Vital Signs and Other Assessments: Regular monitoring of vital signs, hydration status, and overall clinical condition is essential.

5. Nursing Care: Comprehensive nursing care is provided, including hygiene, comfort measures, emotional support, and close monitoring for any complications.

6. Urine and Bowel Care: Regular care and hygiene are provided for the patient’s urinary and bowel functions, especially if they are experiencing incontinence or difficulty with elimination.

7. Terminal Disinfection: After the patient is discharged, thorough terminal disinfection of the patient’s environment (including the room, bed, and equipment) is performed to eliminate any remaining Shigella bacteria.

Immediate Nursing Care

• Rehydration: This is a cornerstone of management, especially in severe cases.

  • Intravenous Fluids: Fluids such as normal saline or Ringer’s lactate are administered intravenously to rapidly correct dehydration and electrolyte imbalances.

  • Oral Rehydration Solutions (ORS): ORS is used for less severe dehydration or as a maintenance fluid after initial IV rehydration.

• Hygiene: Meticulous hygiene is crucial to prevent the spread of infection.

  • Skin Care: Keep the patient’s skin clean and dry, especially the perineal area, to prevent skin breakdown.

  • Mouth Care: Provide regular oral hygiene to prevent mouth sores and maintain comfort.

  • Perineal Care: Frequent and thorough perineal care is essential, especially after each bowel movement, to prevent skin irritation and infection.

• Personal Protective Equipment (PPE): Healthcare workers must wear appropriate PPE, including gloves, aprons, and goggles, when handling anything that may be contaminated with the patient’s stool or other body fluids.

• Handwashing: Frequent and thorough handwashing with soap and water is essential for all healthcare workers and caregivers. Hands should be dried with clean towels.

• Safe Water and Food: Ensure that the patient has access to safe drinking water that has been either treated or boiled. Food should be prepared hygienically.

• Disinfection: Proper disposal of wastes and excreta is crucial. All items contaminated with stool or body fluids should be disinfected using appropriate solutions (e.g., 1% sodium hypochlorite).

• Linen Treatment: Linens (bed sheets, towels, clothing) that have come into contact with the patient should be treated as infected material and handled and laundered accordingly.

• Terminal Disinfection: After the patient is discharged, terminal disinfection of the patient’s environment should be carried out to eliminate any remaining bacteria.

• Monitoring: Close monitoring of the patient’s condition is essential, particularly:

  • Abdominal Pain: Assess the severity and location of abdominal pain.

  • Diarrhea: Monitor the frequency, consistency, and characteristics of the stool (e.g., presence of blood or mucus).

  • Constipation: Although less common, monitor for constipation, which can occur after a period of diarrhea.

  • Complications: Watch for any signs of complications, such as worsening dehydration, electrolyte imbalances, or signs of systemic infection.

  • Report Changes: Promptly report any changes in the patient’s condition to the doctor.

• Diet:

  • Initial Phase: Initially, a clear liquid diet is recommended to rest the bowel and prevent further irritation. Dairy products should be avoided.

  • Gradual Progression: As the patient’s condition improves, the diet can be gradually advanced to a bland diet that is low in fiber. Spicy, fatty, and greasy foods should be avoided.

 Advice on Discharge

• Continue Hydration: Emphasize the importance of maintaining adequate fluid intake to prevent dehydration.

• Handwashing: Reinforce the need for frequent and thorough handwashing, especially after using the toilet and before eating or preparing food.

• Avoid Contact: Advise the patient to avoid close contact with others until they have fully recovered and are no longer shedding the bacteria in their stool.

• Follow-up: Schedule a follow-up appointment with their healthcare provider to ensure complete recovery and to monitor for any potential complications.

Summary of Ward Management

• Admission to a medical ward, ideally in isolation.

• Strict personal hygiene (barrier nursing) to prevent infecting others.

• Disinfection of the patient’s bed and other items used.

• Proper disposal of fecal matter and vomit into a pit latrine or using appropriate disinfectants.

• Regular monitoring of temperature, pulse, respiration, blood pressure, hydration levels, and level of consciousness.

• Providing reassurance and support to the patient and their relatives.

• Maintenance of fluid intake using Oral Rehydration Solution (ORS) or intravenous fluids in severe cases.

• Antibiotic treatment with drugs like nalidixic acid or ciprofloxacin, as prescribed by the doctor.

• Implementing a BRAT diet (bananas, rice, applesauce, toast) to aid in recovery, as tolerated.

• Use of a nasogastric tube for feeding and medication administration if oral intake is not possible.

• Medications for managing nausea and vomiting, such as metoclopramide (Plasil), if needed.

• Close monitoring of hydration levels and maintenance of a fluid balance chart.

Prevention

Preventing shigellosis relies heavily on interrupting the fecal-oral transmission route. Key preventive measures include:

• Maintain Cleanliness: Ensure cleanliness in the environment, particularly in kitchens and food preparation areas. Clean and disinfect kitchen utensils regularly.

• Proper Waste Disposal: Dispose of rubbish properly to prevent fly breeding and contamination of the environment.

• Practice Proper Hand Hygiene: Wash hands thoroughly with soap and water:

  • Before eating or handling food.

  • After using the toilet.

  • After changing diapers.

  • After contact with potentially contaminated surfaces.

• Boil or Treat Drinking Water: Ensure that drinking water is safe by boiling it for at least one minute or treating it with appropriate water purification methods (e.g., chlorination).

• Avoid High-Risk Foods: Avoid consuming high-risk foods such as:

  • Shellfish

  • Raw or semi-cooked food, especially meat and seafood.

• Use Clean Washable Aprons and Caps: When preparing food, use clean, washable aprons and caps to prevent contamination of food from clothing or hair.

• Thoroughly Clean and Wash Food Items: Wash all food items, including fruits and vegetables, thoroughly in clean water before consumption or cooking.

• Store Perishable Food Properly: Store perishable food items in a well-covered refrigerator to prevent bacterial growth.

• Ensure Thorough Cooking of Food: Cook food thoroughly to kill any Shigella bacteria that may be present.

• Consume Food Promptly or Refrigerate Leftovers: Consume cooked food promptly after preparation. If there are leftovers, refrigerate them quickly and reheat them thoroughly before eating.

• Exclude Infected Individuals from Food Handling: Individuals who are infected with Shigella or are asymptomatic carriers should not handle food or provide care to children until they are no longer infectious.

Complications

Shigellosis can lead to several complications, some of which can be serious:

• Perforation: A hole can develop in the intestinal wall, leading to leakage of intestinal contents into the abdominal cavity. This is a serious complication that requires immediate surgical intervention.

• Hemorrhoids and Rectal Prolapse: These can occur as a result of excessive straining during defecation due to tenesmus.

• Hemolytic-Uremic Syndrome (HUS): This is a serious complication that can occur, particularly with Shigella dysenteriae infection. HUS is characterized by the destruction of red blood cells, kidney failure, and low platelet count. It is a medical emergency that requires specialized care.

• Stricture of the Colon: After healing from severe inflammation, narrowing (stricture) of the colon can occur, potentially leading to bowel obstruction.

• Post-dysenteric Colitis (Irritable Bowel Syndrome): Some individuals may experience persistent passage of stool after recovering from shigellosis. This can be accompanied by colicky abdominal pain. In many cases, it resolves within 6 months, but it may become permanent in some individuals.

• Dehydration: Fluid loss due to diarrhea is a common complication and can be severe, especially in young children and the elderly.

• Renal Failure: Kidney dysfunction can occur as a result of severe dehydration or complications like HUS.

• Shock (Hypovolemic): Severe fluid loss can lead to a drop in blood volume, resulting in hypovolemic shock, a life-threatening condition characterized by low blood pressure, rapid heart rate, and organ dysfunction.

• Severe Intestinal Hemorrhage: Bleeding within the intestines can be significant and may require blood transfusions.

Comparison between Bacillary and Amoebic Dysentery: