Shigellosis (Bacillary Dysentery)

1. Clinical Overview

Summary

Shigellosis is an acute invasive bacterial colitis caused by species of the genus Shigella, manifesting as inflammatory diarrhoea with blood and mucus (dysentery). Distinguished by an extraordinarily low infectious dose of 10-100 organisms, shigellosis represents a major global health burden with an estimated 269 million cases and 200,000 deaths annually, predominantly affecting children under 5 years in low-resource settings. [1,2] The clinical spectrum ranges from mild watery diarrhoea typical of S. sonnei infections in high-income countries to severe dysentery with life-threatening complications including haemolytic uraemic syndrome (HUS), toxic megacolon, and seizures associated with S. dysenteriae type 1 in endemic regions. [3,4]

Key Facts

• Definition: Acute invasive bacterial colitis caused by Shigella species (S. dysenteriae, S. flexneri, S. boydii, S. sonnei).
• Global Burden: Estimated 269 million cases and 200,000 deaths annually; 70% mortality in children less than 5 years. [1,2]
• Infectious Dose: 10-100 organisms (lowest of enteric pathogens), enabling person-to-person transmission. [5]
• Mortality: Case fatality rate less than 1% with treatment; up to 10-15% in untreated S. dysenteriae type 1 outbreaks. [3,4]
• Key Investigation: Stool culture remains gold standard; multiplex PCR increasingly used for rapid diagnosis.
• Critical Management: Oral rehydration therapy is cornerstone; antibiotics for dysentery reduce duration and transmission.
• Antimotility Contraindication: Loperamide and other antimotility agents absolutely contraindicated due to risk of toxic megacolon and prolonged pathogen shedding. [6]

Clinical Pearls

The 10-Organism Rule: Shigella possesses the lowest infectious dose of any bacterial enteric pathogen. While Salmonella requires 10⁵-10⁶ organisms and Vibrio cholerae requires 10⁸ organisms to cause infection, as few as 10-100 Shigella bacteria can establish disease. [5] This exceptional acid resistance (survival at pH 2.5) and efficient invasion mechanism explain explosive outbreaks in childcare centres and household settings.

Neurotoxicity Before Dysentery: Shigella can provoke febrile seizures or encephalopathy (Ekiri syndrome) in children, often preceding gastrointestinal symptoms by 12-24 hours. [7] This phenomenon, first described in Japanese children, results from Shiga toxin effects on the central nervous system and systemic inflammatory response, making shigellosis a crucial differential diagnosis for paediatric seizures in endemic areas.

The Post-Infectious Trilogy: Shigellosis is a classic trigger for reactive arthritis (Reiter's syndrome), particularly in HLA-B27 positive individuals, manifesting 2-4 weeks post-infection with the triad of arthritis, urethritis/cervicitis, and conjunctivitis/uveitis ("can't climb, can't pee, can't see"). [8] Additional post-infectious sequelae include prolonged post-infectious irritable bowel syndrome and, rarely, Guillain-Barré syndrome.

Resistance Revolution: Extensively drug-resistant (XDR) Shigella strains, particularly S. sonnei, are spreading globally, especially among men who have sex with men (MSM) networks. [9,10] Azithromycin resistance has emerged in multiple regions, necessitating culture-based susceptibility testing and challenging empirical treatment paradigms.

Why This Matters Clinically

In high-income countries, shigellosis drives outbreaks in childcare centres, long-term care facilities, and MSM communities, with S. sonnei accounting for > 75% of cases. [9,10] In low-income settings, shigellosis remains a leading cause of childhood mortality, with S. flexneri and S. dysenteriae type 1 causing endemic disease and periodic epidemics. [1,2] Rapid recognition enables appropriate antibiotic therapy to reduce duration, prevent transmission, and avert life-threatening complications. The emergence of multidrug resistance demands stewardship and surveillance to preserve therapeutic options. Public health notification and infection control measures are mandatory to interrupt transmission in institutional settings.

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2. Epidemiology

Global Burden

Shigellosis represents a major contributor to the global diarrhoeal disease burden, with the 2016 Global Enteric Multicenter Study (GEMS) identifying Shigella as one of the top four pathogens associated with moderate-to-severe diarrhoea in children under 5 years in developing countries. [1] Recent estimates suggest 269 million cases annually, with approximately 200,000 deaths, predominantly in sub-Saharan Africa and South Asia. [2]

Geographic Distribution:

• Endemic Regions: Sub-Saharan Africa, South Asia (Bangladesh, India, Pakistan), and Central America experience year-round transmission with epidemic peaks. [1,2]
• High-Income Countries: Sporadic cases and outbreaks linked to international travel, MSM transmission, and institutional settings. [9,10]
• Seasonality: Peaks during summer months in temperate climates (fly-mediated transmission) and rainy seasons in tropical regions (water contamination). [11]

The Four Species: Clinical and Epidemiological Distinctions

Mnemonic: "Dirty Fingers Bring Shigella" (Dysenteriae, Flexneri, Boydii, Sonnei)

Demographics

• Age: Peak incidence 1-4 years (limited hygiene capacity); 60-70% of cases occur in children less than 5 years globally. [1,2]
• Sex: Equal distribution in children. In adults, men who have sex with men (MSM) experience disproportionately high rates due to oro-anal transmission. [9,10]
• Socioeconomic Gradient: Strong inverse correlation with access to safe water, sanitation, and hygiene (WASH) infrastructure. [11]

Risk Factors

Host Factors:

• Age less than 5 years: Immature immunity and hygiene behaviours. [1,2]
• Achlorhydria: Reduced gastric acidity (proton pump inhibitor use, atrophic gastritis) lowers infectious dose threshold. [12]
• Immunocompromise: HIV infection (particularly CD4 less than 200), immunosuppressive therapy.
• Malnutrition: Wasting and micronutrient deficiencies increase severity and mortality. [1,2]

Exposure Factors:

Modifiable Preventive Factors:

• Handwashing with soap (reduces transmission by 47%). [11]
• Exclusive breastfeeding for infants less than 6 months (protective effect). [1]
• Safe water access and improved sanitation. [11]
• Proper food handling and preparation practices.

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3. Molecular Pathophysiology

Overview: The Invasion Specialist

Shigella has evolved unique mechanisms to invade colonic epithelium, evade immune responses, and cause inflammatory destruction of the intestinal mucosa. Unlike enterotoxigenic pathogens (E. coli, V. cholerae) that cause secretory diarrhoea, Shigella provokes an intense inflammatory response resulting in dysentery (bloody, mucoid stools with tenesmus). [13]

Step 1: Acid Resistance and Gastric Passage

Shigella survives gastric acid (pH 2.5) through constitutive and inducible acid resistance systems, including:

• Glutamate decarboxylase system: Consumes intracellular protons.
• Arginine decarboxylase system: Generates alkaline amines.

This exceptional acid tolerance accounts for the extraordinarily low infectious dose (10-100 organisms) compared to acid-sensitive enteric pathogens. [5]

Step 2: M-Cell Transcytosis (The Trojan Horse Entry)

Upon reaching the colon, Shigella targets specialized M (microfold) cells overlying Peyer's patches in the follicle-associated epithelium:

1. M-cell invasion: Bacterial type III secretion system (T3SS) injects invasion plasmid antigens (Ipa proteins: IpaB, IpaC, IpaD) that trigger macropinocytosis.
2. Transcytosis: Shigella crosses the epithelial barrier within M-cell vesicles to reach the subepithelial space.
3. Macrophage encounter: Bacteria are phagocytosed by resident macrophages. [13]

Step 3: Macrophage Pyroptosis and Inflammatory Cascade

Shigella escapes the macrophage phagosome using T3SS effectors:

• IpaB: Disrupts phagosomal membrane.
• IpgD: Recruits macrophage membrane to facilitate escape.

Once in the macrophage cytoplasm, Shigella triggers pyroptosis (inflammatory cell death):

1. Activation of caspase-1 via NLRC4 and NLRP3 inflammasomes.
2. Release of IL-1β and IL-18 (pro-inflammatory cytokines).
3. Neutrophil recruitment and transepithelial migration.

This inflammatory response damages the epithelial barrier, creating basolateral access points for bacteria. [13,14]

Step 4: Epithelial Cell Invasion from Basolateral Surface

Released from dying macrophages, Shigella invades colonocytes from the basolateral (serosal) side:

• IpaC: Binds α5β1 integrin and CD44 receptors.
• T3SS injection: Delivers effector proteins (IpaA, IpaC, IpgB1) into epithelial cytoplasm.
• Actin rearrangement: Formation of membrane ruffles and macropinocytic vacuoles that engulf bacteria.

Step 5: Intracellular Actin-Based Motility (The Actin Rocket)

After escaping the entry vacuole, Shigella undergoes actin-based motility:

1. IcsA/VirG: Surface protein recruits neural Wiskott-Aldrich syndrome protein (N-WASP).
2. Arp2/3 complex activation: Nucleates actin polymerization at bacterial pole.
3. Actin comet tail: Propels bacteria through cytoplasm at 0.3 μm/second.
4. Protrusion formation: Bacteria push against cell membrane, forming protrusions into adjacent cells.
5. Double-membrane vacuole: Engulfed by neighbouring cell, escapes, and repeats cycle.

This cell-to-cell spread avoids extracellular immune surveillance and creates characteristic mucosal ulceration. [15,16]

Step 6: Epithelial Destruction and Dysentery

Ongoing invasion, inflammation, and bacterial proliferation result in:

• Mucosal ulceration: Gross and microscopic ulcers in colonic epithelium.
• Vascular damage: Capillary rupture causes bleeding (bloody stool).
• Mucus hypersecretion: Goblet cell stimulation produces mucoid stools.
• Neutrophil transmigration: Creates pathognomonic faecal leukocytes.
• Rectal inflammation: Causes tenesmus (painful straining). [13]

Shiga Toxin: The HUS Mediator

S. dysenteriae type 1 (and rare S. flexneri strains) produce Shiga toxin (Stx), an AB₅ toxin:

Structure:

• A subunit: RNA N-glycosidase that cleaves 28S ribosomal RNA.
• B subunits (×5): Bind globotriaosylceramide (Gb3) receptors on target cells.

Mechanism of Action:

1. Receptor binding: B subunits bind Gb3, highly expressed on renal glomerular endothelium, brain microvascular endothelium, and intestinal epithelium.
2. Endocytosis: Toxin undergoes retrograde transport through Golgi to endoplasmic reticulum.
3. A subunit translocation: Enters cytoplasm and cleaves adenine-4324 from 28S rRNA.
4. Protein synthesis inhibition: Ribosome inactivation halts translation, causing cell death.

Clinical Consequences:

• Renal endothelial injury: Leads to microangiopathic haemolytic anaemia, platelet consumption, and acute kidney injury (HUS triad). [3,4,17]
• CNS toxicity: Seizures, encephalopathy, stroke (Ekiri syndrome). [7]
• Intestinal damage: Enhances mucosal inflammation and bleeding.

HUS Pathogenesis: Shiga toxin damages glomerular endothelium → platelet activation and fibrin deposition → mechanical haemolysis (schistocytes) → thrombocytopenia → acute kidney injury. [17]

Genetic Basis: The Virulence Plasmid

Shigella virulence depends on a large (180-220 kb) virulence plasmid encoding:

• T3SS apparatus: Mxi-Spa proteins forming the injectisome.
• Invasion plasmid antigens (Ipa): IpaA, IpaB, IpaC, IpaD.
• IcsA/VirG: Actin-based motility.
• Ipa effectors: IpgB1, IpgD, and others modulating host signalling.

Loss of this plasmid renders Shigella avirulent. [13]

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4. Clinical Presentation

Incubation Period

1-3 days (range 12 hours to 7 days) following ingestion of contaminated food, water, or person-to-person transmission. [6]

Typical Clinical Course

Phase 1: Watery Diarrhoea (12-24 hours) Initial small bowel involvement:

• Watery, non-bloody diarrhoea (3-5 stools/day).
• Low-grade fever (38-39°C).
• Mild abdominal cramping.
• Malaise, anorexia.

Phase 2: Dysentery (24-72 hours) Colonic invasion and inflammation:

• Frequent, small-volume stools: 10-30 episodes/day.
• Frank blood and mucus: "Currant jelly" or "raspberry jam" appearance.
• Tenesmus: Painful rectal spasm, persistent urge to defecate despite empty rectum.
• Left lower quadrant pain: Colicky, relieved transiently by defecation.
• High fever: 39-40°C, rigors.
• Systemic toxicity: Prostration, dehydration.

Duration:

• Untreated: 7-10 days, gradual resolution.
• Antibiotic-treated: 2-3 days to clinical improvement. [6,18]

Symptom Spectrum by Species

Atypical and Complicated Presentations

Neurological Manifestations:

• Febrile seizures: Occur in 10-45% of children less than 5 years with shigellosis (vs. 2-5% with other febrile illnesses). [7]
• Ekiri syndrome: Encephalopathy with altered consciousness, seizures, hypoglycaemia; described in Japanese and South Asian children with S. dysenteriae type 1.
• Meningism: Headache, neck stiffness without CSF pleocytosis.

Haemolytic Uraemic Syndrome (HUS): Occurs in 10-15% of S. dysenteriae type 1 infections, typically 5-10 days after diarrhoea onset. [3,4,17]

Clinical Features:

• Anaemia: Pallor, fatigue, tachycardia.
• Thrombocytopenia: Petechiae, mucosal bleeding.
• Acute kidney injury: Oliguria/anuria, oedema, hypertension.
• Neurological: Seizures (30%), altered consciousness, stroke.

Other Complications:

• Toxic megacolon: Abdominal distension, absent bowel sounds, systemic toxicity; transverse colon > 6 cm on X-ray.
• Intestinal perforation: Peritonitis, rigid abdomen; mortality 30-50%.
• Rectal prolapse: Common in malnourished children due to severe tenesmus.
• Sepsis: Rare (Shigella bacteraemia less than 5% cases) but associated with high mortality. [6]
• Hyponatraemia: SIADH from severe illness.
• Hypoglycaemia: Particularly in malnourished children.

Physical Examination Findings

General Appearance:

• Dehydration assessment (WHO classification):
  • "Mild (3-5% loss): Thirsty, alert, normal vital signs."
  • "Moderate (6-9% loss): Irritable, sunken eyes/fontanelle, reduced skin turgor (skin pinch > 2 seconds), dry mucous membranes, tachycardia."
  • "Severe (≥10% loss): Lethargic/unconscious, weak/absent pulse, cool extremities, prolonged capillary refill, anuric."

Abdominal Examination:

• Inspection: Distension (if ileus/megacolon developing).
• Palpation: Tenderness, especially left lower quadrant (sigmoid colon); guarding if peritonitis.
• Percussion: Tympany if ileus; loss of liver dullness if perforation.
• Auscultation: Hyperactive bowel sounds initially; diminished/absent if toxic megacolon or ileus.
• Rectal examination: Painful; fresh blood on glove; assess sphincter tone.

Systemic Examination:

• Neurological: Altered mental status, seizures, meningism.
• Skin: Petechiae/purpura (if HUS), poor perfusion.
• Mucous membranes: Pallor (anaemia), jaundice (haemolysis).

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5. Differential Diagnosis

Infectious Causes of Bloody Diarrhoea

Non-Infectious Causes

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6. Investigations

Initial Laboratory Tests

Full Blood Count (FBC):

• White cell count: Leukocytosis (10-20 × 10⁹/L) with neutrophilia and "left shift" (increased band forms).
• Haemoglobin: Normal unless HUS develops (then anaemia with schistocytes).
• Platelets: Normal initially; thrombocytopenia if HUS (typically less than 150 × 10⁹/L, often less than 50).

Urea and Electrolytes:

• Sodium: Hyponatraemia (SIADH from severe illness).
• Potassium: Hypokalaemia (gastrointestinal losses).
• Urea and creatinine: Elevated if dehydration or HUS-associated acute kidney injury.

Inflammatory Markers:

• C-reactive protein (CRP): Elevated (> 50 mg/L), distinguishing bacterial from viral gastroenteritis.
• Procalcitonin: May be elevated in severe cases.

Blood Culture:

• Positive in less than 5% of shigellosis cases (unlike Salmonella enterica where bacteraemia occurs in 10-15%).
• Shigella bacteraemia associated with high mortality and often indicates immunocompromise. [6]

Stool Studies

Macroscopic Inspection:

• Presence of visible blood and mucus supports bacterial colitis.
• "Currant jelly" or "raspberry jam" appearance characteristic.

Stool Microscopy:

• Faecal leukocytes (polymorphonuclear cells): Abundant in invasive bacterial diarrhoea.
• Red blood cells: Present.
• Diagnostic pearl: If red cells present WITHOUT leukocytes, consider Entamoeba histolytica (amoebic dysentery) or enterotoxigenic E. coli.

Stool Culture (Gold Standard):

• Selective media: MacConkey agar, xylose-lysine-deoxycholate (XLD) agar, Salmonella-Shigella (SS) agar.
• Shigella characteristics: Non-lactose fermenting (colourless colonies on MacConkey); non-motile; produces indole.
• Sensitivity: 60-85% (reduced by prior antibiotic use).
• Time to result: 48-72 hours for preliminary identification; 3-5 days for species identification and antibiotic susceptibility.
• Antimicrobial susceptibility testing: Essential given rising resistance. [9,10,18]

Multiplex Molecular Testing (PCR):

• Targets: ipaH gene (invasion plasmid antigen H), conserved across all Shigella species.
• Platforms: Biofire FilmArray GI Panel, Luminex xTAG GPP, Seegene Allplex.
• Advantages: Results in 1-5 hours; detects multiple pathogens simultaneously; higher sensitivity than culture (90-95%).
• Limitations: Cannot provide antibiotic susceptibility; detects DNA (may represent non-viable organisms or asymptomatic carriage). [19]

Shiga Toxin Testing:

• Indicated when S. dysenteriae type 1 suspected or HUS develops.
• Enzyme immunoassay (EIA): Detects Stx1 and Stx2 in stool.
• PCR: Identifies stx genes.

Investigations for Complications

HUS Workup (if oliguria, pallor, petechiae develop):

Imaging:

Abdominal X-ray (plain film):

• Indications: Suspected toxic megacolon, perforation, or severe abdominal pain.
• Findings:
  • Toxic megacolon: Transverse colon diameter > 6 cm; loss of haustral folds; "thumbprinting" (mucosal oedema).
  • "Perforation: Free air under diaphragm (erect film)."
  • "Ileus: Dilated bowel loops, air-fluid levels."

CT Abdomen/Pelvis (with IV contrast):

• Indications: Severe illness, suspected perforation, or diagnostic uncertainty.
• Findings: Colonic wall thickening (particularly left colon and rectum), pericolonic fat stranding, ascites (if perforation).

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7. Management

General Principles

1. Assess and correct dehydration (first priority).
2. Empirical antibiotics for dysentery (bloody stools, fever, systemic toxicity).
3. Avoid antimotility agents (absolute contraindication).
4. Monitor for complications (HUS, toxic megacolon, seizures).
5. Public health notification (mandatory reporting in most jurisdictions).
6. Infection control (isolation, hand hygiene). [6,18]

Fluid and Electrolyte Management

Oral Rehydration Therapy (ORT):

• First-line for mild-moderate dehydration.
• WHO low-osmolarity ORS formula:
  • "Sodium: 75 mmol/L"
  • "Potassium: 20 mmol/L"
  • "Chloride: 65 mmol/L"
  • "Glucose: 75 mmol/L"
  • "Osmolarity: 245 mOsm/L"
• Dosing:
  • "Mild dehydration: 50 mL/kg over 4 hours."
  • "Moderate dehydration: 100 mL/kg over 4 hours."
  • "Maintenance: 10 mL/kg after each loose stool."

Intravenous Rehydration:

• Indications: Severe dehydration, altered consciousness, persistent vomiting, ileus.
• Fluid choice: Isotonic crystalloid (0.9% sodium chloride, Ringer's lactate).
• Dosing:
  • "Bolus: 20 mL/kg over 15-30 minutes; repeat if needed."
  • "Deficit replacement: 100 mL/kg over 3-6 hours."
  • "Maintenance: Age-appropriate maintenance fluids plus ongoing losses."

Zinc Supplementation (Children):

• Evidence: Reduces diarrhoea duration by 1 day and severity. [20]
• Dosing:
  • "less than 6 months: 10 mg/day for 10-14 days."
  • "> 6 months: 20 mg/day for 10-14 days."

Antibiotic Therapy

Indications:

• Dysentery (bloody diarrhoea) with fever and systemic toxicity.
• Immunocompromise (HIV, immunosuppressive therapy).
• Severe disease requiring hospitalization.
• Public health considerations: Food handlers, healthcare workers, childcare workers (to reduce shedding and transmission). [6,18]

Benefits of Antibiotics:

• Reduce illness duration by 2-3 days. [18]
• Reduce faecal shedding duration from weeks to days.
• Prevent complications in high-risk patients.
• Decrease household transmission.

Empirical Antibiotic Selection:

Recommendations must account for local resistance patterns and patient factors. Rising global resistance necessitates culture-based susceptibility testing whenever possible. [9,10,18]

First-Line Agents (if susceptible):

Alternative Agents (based on susceptibility):

• Cefixime: 400 mg PO BD × 5 days (paediatric: 8 mg/kg BD).
• Pivmecillinam: 400 mg PO TDS × 5 days (used in Europe; limited availability).

Historically Used (Now High Resistance):

• Trimethoprim-sulfamethoxazole: Resistance > 80% globally; rarely used. [10,18]
• Ampicillin/amoxicillin: Widespread resistance; not recommended.
• Nalidixic acid: Largely replaced by fluoroquinolones.

Special Populations:

Pregnancy:

• Preferred: Azithromycin.
• Alternative: Ceftriaxone.
• Avoid: Fluoroquinolones (theoretical cartilage toxicity).

HIV/Immunocompromise:

• Longer duration (7-10 days) often needed.
• IV therapy initially if severe.
• Monitor for relapse.

Antimotility Agents: Absolute Contraindication

Contraindicated Agents:

• Loperamide (Imodium)
• Diphenoxylate-atropine (Lomotil)
• Codeine
• Morphine derivatives

Rationale:

• Slow intestinal transit → prolonged contact between mucosa and toxin/bacteria.
• Increased risk of toxic megacolon.
• Prolonged pathogen shedding.
• Increased HUS risk with Shiga toxin-producing strains. [6]

Evidence: Observational studies in the 1970s-1980s linked antimotility agent use in shigellosis with prolonged fever, increased complications, and fatal toxic megacolon. Antimotility agents remain absolutely contraindicated in all suspected or confirmed bacterial dysentery. [6]

Management of Complications

Haemolytic Uraemic Syndrome (HUS):

• Early nephrology consultation.
• Supportive care:
  • Fluid and electrolyte management (may require restriction if anuric).
  • Hypertension control (calcium channel blockers).
  • Transfusion if severe anaemia (Hb less than 60-70 g/L) or active bleeding.
  • Platelet transfusion generally avoided unless life-threatening bleeding (may worsen thrombotic microangiopathy).
• Renal replacement therapy: Haemodialysis or peritoneal dialysis if severe AKI (30-50% of HUS cases).
• Avoid: Antibiotics during established HUS (theoretical Shiga toxin release from bacterial lysis; controversial). [17]
• Outcome: Mortality 3-5%; chronic kidney disease in 5-10%; end-stage renal disease in 3-5%. [17]

Toxic Megacolon:

• Immediate surgical consultation.
• Nil per os (NPO), nasogastric decompression.
• IV fluids, correct electrolytes.
• Broad-spectrum IV antibiotics (add anaerobic coverage: metronidazole or piperacillin-tazobactam).
• Serial abdominal X-rays to monitor colonic diameter.
• Colectomy if perforation or failed medical management (24-48 hours).

Seizures:

• Assess and manage ABCs (airway, breathing, circulation).
• Check glucose (treat hypoglycaemia).
• Antipyretics (paracetamol).
• Benzodiazepines (lorazepam 0.1 mg/kg IV) if prolonged.
• Investigate: Consider lumbar puncture if meningitis cannot be excluded clinically.

Intestinal Perforation:

• Emergency surgery (exploratory laparotomy, resection of perforated segment).
• Broad-spectrum antibiotics covering enteric flora.

Disposition

Admission Criteria:

• Severe dehydration (> 9% weight loss).
• Inability to tolerate oral fluids (persistent vomiting).
• Suspected complications (HUS, toxic megacolon, perforation).
• Altered mental status or seizures.
• Age less than 6 months with dysentery.
• Immunocompromise.
• Social factors precluding safe discharge.

Discharge Criteria:

• Tolerating oral fluids and ORS.
• Improving clinical status.
• No signs of complications.
• Reliable follow-up.
• Caregiver education on red flags.

Public Health Measures

Notification: Shigellosis is a notifiable disease in most jurisdictions (UK, USA, Canada, Australia, WHO International Health Regulations). [6]

Exclusion Guidelines:

Outbreak Investigation:

• Case finding and contact tracing.
• Environmental sampling (food, water).
• Enhanced surveillance.
• Targeted health education (hand hygiene, food safety).

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8. Complications

Immediate (During Acute Illness)

Dehydration and Electrolyte Disturbances:

• Hypovolaemic shock: Hypotension, tachycardia, reduced consciousness.
• Hypokalaemia: Muscle weakness, arrhythmias.
• Hyponatraemia: SIADH in severe illness.
• Metabolic acidosis: From dehydration and shock.

Neurological:

• Febrile seizures: 10-45% of children less than 5 years. [7]
• Encephalopathy (Ekiri syndrome): Altered consciousness, lethargy, hypoglycaemia.
• Cerebral oedema: Rare; associated with severe hyponatraemia.

Gastrointestinal:

• Rectal prolapse: Common in malnourished children; severe tenesmus.
• Toxic megacolon: Colonic dilation > 6 cm; systemic toxicity; perforation risk.
• Intestinal perforation: Mortality 30-50%; requires emergency surgery.
• Paralytic ileus: Delayed gastric emptying, abdominal distension.

Haematological:

• Shigella bacteraemia: less than 5% of cases; high mortality (20-40%); immunocompromise risk factor.

Early (Days to Weeks)

Haemolytic Uraemic Syndrome (HUS):

• Incidence: 10-15% of S. dysenteriae type 1 infections; rare with other species. [3,4,17]
• Onset: 5-10 days after diarrhoea onset.
• Triad: Microangiopathic haemolytic anaemia + thrombocytopenia + acute kidney injury.
• Mortality: 3-5% in specialized centres; up to 15% in resource-limited settings. [17]
• Chronic sequelae: Chronic kidney disease 5-10%; end-stage renal disease 3-5%; hypertension 10-20%.

Protein-Losing Enteropathy:

• Severe mucosal damage → loss of serum proteins → hypoalbuminaemia, oedema.

Haemorrhage:

• Severe colonic ulceration → life-threatening bleeding (rare).

Late (Weeks to Months)

Reactive Arthritis (Reiter's Syndrome):

• Incidence: 1-3% of shigellosis cases; up to 20% in HLA-B27 positive individuals. [8]
• Onset: 2-4 weeks post-infection.
• Classic triad:
  • "Arthritis: Asymmetric oligoarthritis affecting large joints (knees, ankles, wrists); inflammatory."
  • "Urethritis/cervicitis: Sterile urethritis, dysuria."
  • "Conjunctivitis/uveitis: Red eye, photophobia; anterior uveitis."
• Additional features: Enthesitis (heel pain), dactylitis (sausage digits), mucocutaneous lesions (keratoderma blennorrhagicum, circinate balanitis), sacroiliitis.
• Chronicity: 15-30% develop chronic spondyloarthropathy.
• Diagnosis: Clinical; elevated inflammatory markers; HLA-B27 testing; synovial fluid aspiration (sterile, inflammatory).
• Management: NSAIDs, intra-articular corticosteroids, DMARDs (sulfasalazine, methotrexate) if chronic. [8]

Post-Infectious Irritable Bowel Syndrome (PI-IBS):

• Incidence: 10-15% of shigellosis cases develop chronic functional bowel symptoms. [21]
• Risk factors: Female sex, prolonged acute illness, psychological stress.
• Symptoms: Abdominal pain, bloating, altered bowel habit (Rome IV criteria).
• Duration: Months to years; gradually improves in most.

Guillain-Barré Syndrome:

• Rare post-infectious complication; ascending flaccid paralysis.

Malnutrition:

• Prolonged diarrhoea in children → wasting, growth faltering.

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9. Prognosis & Outcomes

Natural History (Untreated)

• Duration: 7-10 days; gradual resolution.
• Shedding: Organisms shed in stool for 1-4 weeks (median 2 weeks).
• Mortality: 10-15% in S. dysenteriae type 1 outbreaks without treatment. [3,4]

With Appropriate Treatment

• Clinical improvement: Fever resolves within 24 hours; diarrhoea decreases within 48-72 hours.
• Duration: 2-3 days to significant improvement. [18]
• Shedding: Reduced to less than 1 week with effective antibiotics.
• Mortality: less than 1% in settings with access to rehydration and antibiotics. [6]

Prognostic Factors

Poor Prognostic Indicators:

• Age less than 1 year or > 65 years.
• Severe malnutrition (weight-for-height Z-score -3 or less).
• Immunocompromise (HIV with CD4 less than 200, chemotherapy, immunosuppressive therapy).
• S. dysenteriae type 1 infection (HUS risk). [3,4]
• Delayed presentation (> 5 days of symptoms).
• Complications (HUS, toxic megacolon, sepsis).
• Lack of access to healthcare facilities.

Favourable Prognostic Indicators:

• Age 1-5 years (if well-nourished).
• S. sonnei infection (mild disease).
• Early initiation of ORT and appropriate antibiotics.
• Access to tertiary care (for HUS management).

Long-Term Outcomes

Most Patients:

• Complete recovery within 1-2 weeks.
• No long-term sequelae.

HUS Survivors:

• 90-95% recover renal function.
• 5-10% develop chronic kidney disease stage 3-5.
• 3-5% require long-term dialysis or transplantation. [17]

Reactive Arthritis:

• 70-80% recover within 6-12 months.
• 15-30% develop chronic spondyloarthropathy requiring long-term management. [8]

Mortality Rates

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10. Prevention

Primary Prevention

Water, Sanitation, and Hygiene (WASH):

• Safe water: Chlorination, boiling, or filtration of drinking water.
• Sanitation: Access to improved toilets; proper disposal of human waste.
• Handwashing: Soap and water after toilet use, before food preparation, before eating; reduces transmission by 47%. [11]

Food Safety:

• Proper food handling and storage (refrigeration less than 5°C).
• Cooking food to safe temperatures (> 70°C).
• Avoiding cross-contamination (separate raw and cooked foods).
• Exclusion of symptomatic food handlers.

Breastfeeding:

• Exclusive breastfeeding for infants less than 6 months provides passive immunity and reduces shigellosis risk. [1]

Vaccination (Investigational):

• No licensed vaccine currently available.
• Candidates in development:
  • "Live attenuated oral vaccines: CVD 1208, SC602, WRSs2, WRSs3."
  • "Conjugate vaccines: Shigella O-antigen conjugated to carrier proteins (targeting S. sonnei, S. flexneri serotypes)."
  • "Subunit vaccines: IpaB, IpaD, IcsA antigens."
• Challenges: Multiple species/serotypes; difficulty inducing mucosal immunity; limited correlates of protection. [22]

Secondary Prevention (Outbreak Control)

Case Isolation:

• Isolate symptomatic individuals until 48 hours symptom-free.
• Separate bathroom facilities if possible.

Contact Tracing:

• Identify and monitor close contacts (household, childcare).
• Exclude from high-risk activities (food handling, childcare) until clearance.

Chemoprophylaxis:

• Not routinely recommended.
• May consider for high-risk contacts (immunocompromised) during outbreaks; azithromycin 500 mg single dose (adults).

Environmental Cleaning:

• Disinfection of contaminated surfaces (1:10 bleach solution, quaternary ammonium compounds).
• Proper handling and disposal of soiled linens and nappies.

Tertiary Prevention (Reducing Complications)

• Early recognition and treatment of shigellosis with antibiotics (reduces HUS risk). [17]
• Avoidance of antimotility agents (reduces toxic megacolon risk). [6]
• Zinc supplementation in children (reduces severity and duration). [20]

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11. Evidence & Guidelines

Key Clinical Practice Guidelines

Infectious Diseases Society of America (IDSA) / Infectious Diseases Society of America (IDSA) 2017: Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea

• Empirical antibiotics recommended for dysentery (bloody diarrhoea with fever).
• Fluoroquinolones or azithromycin first-line if susceptible.
• Stool culture and susceptibility testing to guide therapy.
• Antimotility agents contraindicated in bloody diarrhoea. [18]

World Health Organization (WHO) 2005: Guidelines for the Control of Shigellosis, Including Epidemics Due to Shigella dysenteriae Type 1

• Case management: ORS and antibiotics for dysentery.
• Epidemic control: Surveillance, case isolation, WASH interventions.
• Antibiotic selection based on local resistance patterns.
• Zinc supplementation for children. [6]

UK Health Security Agency (UKHSA): Public Health Control and Management of Shigellosis

• Notification and exclusion policies.
• Outbreak investigation protocols.
• Antimicrobial prescribing guidance based on national surveillance. [10]

Centers for Disease Control and Prevention (CDC): Shigellosis: Information for Healthcare Professionals

• Diagnosis, treatment, and public health management.
• Antimicrobial resistance surveillance (NARMS). [9]

Landmark Studies and Systematic Reviews

Global Burden:

1. Kotloff KL et al. (2013). Burden and aetiology of diarrhoeal disease in infants and young children in developing countries (the Global Enteric Multicenter Study, GEMS): a prospective, case-control study. Lancet 2013;382(9888):209-222. PMID: 23680352

   • Identified Shigella as one of the top 4 pathogens causing moderate-to-severe diarrhoea in children less than 5 years in sub-Saharan Africa and South Asia. [1]

2. GBD 2016 Diarrhoeal Disease Collaborators. (2018). Estimates of the global, regional, and national morbidity, mortality, and aetiologies of diarrhoea in 195 countries: a systematic analysis for the Global Burden of Disease Study 2016. Lancet Infect Dis 2018;18(11):1211-1228. PMID: 30243583

   • Estimated 269 million Shigella cases and 200,000 deaths annually worldwide. [2]

Antibiotic Therapy: 3. Christopher PR et al. (2010). Antibiotic therapy for Shigella dysentery. Cochrane Database Syst Rev 2010;(8):CD006784. PMID: 20687081

• Meta-analysis: Antibiotics shorten clinical illness by 2.5 days and bacteriological failure by 4.3 days compared to placebo. [18]

Antimicrobial Resistance: 4. Gu B et al. (2021). Global trend of antimicrobial resistance in Shigella: a systematic review and meta-analysis. J Antimicrob Chemother 2021;76(11):2833-2846. PMID: 34347082

• High global resistance to ampicillin (84%), trimethoprim-sulfamethoxazole (77%), and increasing ciprofloxacin resistance (26%).

5. Baker KS et al. (2018). Travel- and community-based transmission of multidrug-resistant Shigella sonnei lineage among international Orthodox Jewish communities. Emerg Infect Dis 2016;22(8):1545-1553. PMID: 27322450

   • Documented international spread of XDR S. sonnei clone. [9]

6. Williamson DA et al. (2016). High rate of antimicrobial resistance in Shigella from sexual transmission in men who have sex with men. J Antimicrob Chemother 2019;74(7):2007-2012. PMID: 30968151

   • Identified MSM transmission networks as hotspots for MDR Shigella. [10]

Haemolytic Uraemic Syndrome: 7. Wong CS et al. (2012). Risk factors for the hemolytic uremic syndrome in children infected with Escherichia coli O157:H7: a multivariable analysis. Clin Infect Dis 2012;55(1):33-41. PMID: 22431799

• HUS occurs in 10-15% of Shiga toxin-producing bacterial infections (STEC and S. dysenteriae type 1). [17]

Zinc Supplementation: 8. Lazzerini M, Wanzira H. (2016). Oral zinc for treating diarrhoea in children. Cochrane Database Syst Rev 2016;12:CD005436. PMID: 27996088

• Zinc reduces diarrhoea duration by approximately 1 day and severity in children. [20]

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12. Special Populations

Paediatric Considerations

Epidemiology:

• Children less than 5 years account for 60-70% of global shigellosis burden. [1,2]
• Peak incidence 1-4 years (hygiene behaviours, daycare exposure).

Clinical Features:

• Higher risk of seizures (10-45% vs. 2-5% with other febrile illnesses). [7]
• More rapid dehydration due to higher surface area-to-volume ratio.
• Rectal prolapse common in malnourished children.

Management:

• Rehydration: ORS preferred; age-appropriate IV fluids if needed.
• Antibiotics: Azithromycin first-line (10 mg/kg/day × 3 days).
• Zinc supplementation: 10 mg (less than 6 months) or 20 mg (> 6 months) daily × 10-14 days. [20]
• Seizure management: Benzodiazepines; check glucose.

Pregnancy

Risks:

• Dehydration → uterine hypoperfusion → preterm labour.
• Severe illness → maternal mortality (especially S. dysenteriae type 1).

Management:

• Aggressive rehydration.
• Antibiotics: Azithromycin preferred; ceftriaxone if severe.
• Avoid: Fluoroquinolones (theoretical cartilage toxicity).
• Fetal monitoring if > 24 weeks gestation.

HIV and Immunocompromise

Epidemiology:

• Increased incidence and severity in HIV (especially CD4 less than 200).
• Higher risk of bacteraemia (20-30% vs. less than 5% in immunocompetent). [6]

Clinical Features:

• Prolonged symptoms (weeks to months).
• Chronic diarrhoea.
• Relapse common.

Management:

• Longer antibiotic duration (7-10 days).
• IV therapy initially if severe.
• Secondary prophylaxis if recurrent (ciprofloxacin 500 mg BD or azithromycin 500 mg weekly).

Elderly

Risks:

• Higher mortality (comorbidities, frailty).
• Atypical presentation (delirium without prominent diarrhoea).
• Dehydration complications (acute kidney injury, thrombosis).

Management:

• Low threshold for admission.
• IV rehydration.
• Monitor electrolytes and renal function closely.

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13. Patient Education & Layperson Explanation

What is Shigellosis?

Shigellosis is an infection of the bowel caused by Shigella bacteria. It causes inflammation and damage to the lining of the intestine, leading to diarrhoea that often contains blood or slime (mucus). You may also experience stomach cramps, fever, and feeling generally unwell. Shigellosis is sometimes called "dysentery" or "traveller's diarrhoea."

How Did I Get It?

Shigella is extremely contagious. You only need to swallow a tiny amount—as few as 10 bacteria—to get sick. You can catch it by:

• Person-to-person: Touching surfaces or objects contaminated with tiny amounts of faeces (door handles, toys, nappies), then touching your mouth.
• Food: Eating food prepared by someone with shigellosis who didn't wash their hands properly.
• Water: Drinking contaminated water or swimming in contaminated pools.
• Sexual contact: Direct faecal-oral contact (particularly in men who have sex with men).

What Are the Symptoms?

• Diarrhoea: Frequent, small amounts, often with visible blood or mucus.
• Stomach cramps: Cramping pain, especially in the lower abdomen.
• Fever: Often high (39-40°C).
• Tenesmus: A constant urge to empty your bowels even when they're already empty (very uncomfortable).
• Nausea and loss of appetite.

Symptoms usually start 1-3 days after exposure and last 5-7 days without treatment.

How is it Treated?

1. Drink plenty of fluids: The most important treatment is replacing fluids lost through diarrhoea. Drink oral rehydration solution (ORS), available from pharmacies, or water, diluted fruit juice, and clear soups. Avoid sugary fizzy drinks and undiluted fruit juice (can worsen diarrhoea).

2. Antibiotics: If you have bloody diarrhoea, fever, or severe symptoms, your doctor will prescribe antibiotics (usually azithromycin or ciprofloxacin for 3 days). Antibiotics help you recover faster and prevent spreading the infection to others.

3. Do NOT take anti-diarrhoea medicines like loperamide (Imodium) or Pepto-Bismol without asking your doctor. These can make shigellosis worse and cause serious complications.

4. Rest: Your body needs energy to fight the infection.

How Long Will I Be Sick?

• Without antibiotics: 7-10 days.
• With antibiotics: Most people feel better within 2-3 days.

You can still spread the infection for 1-4 weeks after symptoms resolve if you don't take antibiotics, but antibiotics reduce this to a few days.

When Should I Seek Urgent Medical Help?

Call 999 or go to A&E if:

• You or your child stops passing urine (sign of kidney problems).
• You notice unusual paleness, bruising, or bleeding (sign of blood disorder).
• You develop severe abdominal pain with a hard, rigid belly (sign of perforation).
• You or your child has a seizure (fit).
• You become confused or very drowsy.
• You cannot keep down any fluids (severe vomiting).

Contact your GP or NHS 111 if:

• There is a lot of blood in your stools.
• You have a high fever (> 39°C) that won't come down.
• Signs of dehydration: very dry mouth, dizziness when standing, dark urine, passing very little urine.

How Can I Prevent Spreading It to Others?

Shigella spreads very easily, so strict hygiene is essential:

• Wash your hands thoroughly with soap and water for at least 20 seconds, especially after using the toilet, before preparing food, and before eating.
• Stay off work or school until you've had no diarrhoea for 48 hours.
• Don't prepare food for others while you're ill and for 48 hours after symptoms stop.
• Don't share towels, flannels, or eating utensils.
• Avoid swimming in pools or natural bodies of water until 48 hours after symptoms resolve.
• Clean toilets and surfaces with bleach-based disinfectant daily.

Can I Prevent Shigellosis?

• Handwashing: The single most effective prevention. Always wash hands with soap after using the toilet, changing nappies, and before eating.
• Safe food and water: When travelling, drink bottled or boiled water; avoid ice; eat freshly cooked, hot food; peel fruits yourself.
• Avoid sexual practices that involve faecal-oral contact.

What About Long-Term Effects?

Most people recover completely. However:

• Joint pain (reactive arthritis): 1-3% develop arthritis 2-4 weeks after infection, particularly if you carry the HLA-B27 gene. This usually resolves but can become chronic.
• Irritable bowel syndrome: 10-15% experience ongoing bowel symptoms (bloating, cramping, altered bowel habit) that gradually improve.
• Kidney problems: Rare, but Shigella dysenteriae type 1 can cause kidney damage (haemolytic uraemic syndrome).

If you develop persistent symptoms, see your GP.

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14. Clinical Vignettes

Case 1: Classic Shigellosis in a Child

Presentation: A 3-year-old girl presents to her GP with a 2-day history of frequent diarrhoea containing blood and mucus. Her mother reports 10-15 stools per day, fever (39.5°C), abdominal cramps, and straining when passing stools. She attends a local nursery where two other children have similar symptoms. She appears mildly dehydrated (sunken eyes, reduced skin turgor) but is alert.

Investigations:

• Stool culture: Shigella sonnei isolated; susceptible to azithromycin and ciprofloxacin.
• FBC: WCC 14 × 10⁹/L (neutrophilia).
• CRP: 65 mg/L.

Management:

• Oral azithromycin 10 mg/kg/day × 3 days.
• Oral rehydration solution 100 mL/kg over 4 hours.
• Zinc 20 mg daily × 14 days.
• Exclusion from nursery until 48 hours symptom-free.
• Public health notification.

Outcome: Fever resolved within 24 hours; diarrhoea improving by day 3. Returned to nursery 1 week later. Household contacts remained asymptomatic (good hand hygiene).

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Case 2: XDR Shigella sonnei in MSM

Presentation: A 32-year-old man presents to sexual health clinic with 4-day history of bloody diarrhoea, abdominal pain, and fever. He reports oro-anal sexual contact with a male partner 5 days prior. He is systemically unwell but not dehydrated.

Investigations:

• Stool PCR: Shigella DNA (ipaH gene) detected.
• Stool culture: Shigella sonnei isolated; resistant to ciprofloxacin, azithromycin, and trimethoprim-sulfamethoxazole; susceptible to ceftriaxone.
• FBC, U&E, CRP: Inflammatory picture.

Management:

• IV ceftriaxone 2g daily × 5 days (admitted for 2 days, then switched to oral cefixime to complete course).
• Oral rehydration.
• Partner notification and treatment.
• Public health notification (XDR outbreak investigation).
• Sexual health counselling (condom use, oral-anal barriers).

Outcome: Clinical improvement within 48 hours. Follow-up stool cultures negative after treatment completion. Partner also diagnosed and treated.

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Case 3: HUS Complicating S. dysenteriae Type 1

Presentation: A 4-year-old boy presents to A&E with 5-day history of bloody diarrhoea and fever. He recently returned from visiting family in Bangladesh. Over the past 24 hours, he has passed very little urine, become pale, and developed petechiae. On examination: pallor, petechial rash, mild oedema, hypertensive (BP 110/70 mmHg).

Investigations:

• FBC: Hb 65 g/L, platelets 45 × 10⁹/L, WCC 18 × 10⁹/L.
• Blood film: Schistocytes, helmet cells (microangiopathic haemolytic anaemia).
• U&E: Creatinine 280 μmol/L (AKI), urea 22 mmol/L.
• LDH: 1200 U/L (markedly elevated).
• Urinalysis: Haematuria, proteinuria.
• Stool culture: Shigella dysenteriae type 1; Shiga toxin positive.

Diagnosis: Haemolytic uraemic syndrome (HUS) secondary to Shigella dysenteriae type 1.

Management:

• Immediate paediatric nephrology consultation.
• Admission to paediatric intensive care unit.
• Fluid restriction (oliguria).
• Hypertension management: Amlodipine.
• Transfusion: Packed red cells (Hb less than 60 g/L).
• Haemodialysis: Initiated on day 2 (severe AKI, hyperkalaemia).
• No antibiotics during acute HUS phase (already established).

Outcome: Required dialysis for 2 weeks. Gradual recovery of renal function. Discharged after 3 weeks with creatinine 90 μmol/L. Long-term nephrology follow-up planned (risk of chronic kidney disease).

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15. Exam-Focused Pearls

High-Yield Facts for Postgraduate Examinations (MRCP, MRCPCH, FRACP)

1. Shigellosis has the LOWEST infectious dose of any bacterial pathogen (10-100 organisms vs. 10⁵-10⁶ for Salmonella, 10⁸ for Vibrio cholerae). [5]

2. Antimotility agents (loperamide) are ABSOLUTELY CONTRAINDICATED in bloody diarrhoea due to risk of toxic megacolon and prolonged shedding. [6]

3. Shigella bacteraemia is RARE (less than 5%) compared to Salmonella enterica (10-15% bacteraemia rate). When it occurs, it suggests immunocompromise. [6]

4. HUS occurs in 10-15% of S. dysenteriae type 1 infections but is rare with other Shigella species (unlike STEC where HUS occurs with multiple serotypes). [3,4,17]

5. Faecal leukocytes are ABUNDANT in shigellosis. If red cells present WITHOUT leukocytes, consider Entamoeba histolytica (amoebic dysentery).

6. Shigellosis is a NOTIFIABLE DISEASE in most jurisdictions. Food handlers require 2 negative stool samples before return to work in many regions. [6]

7. S. sonnei accounts for > 75% of cases in high-income countries but causes milder disease (often no visible blood). S. dysenteriae type 1 causes the most severe disease with highest HUS risk. [3,4,9,10]

8. Reactive arthritis occurs in 1-3% overall, but up to 20% in HLA-B27 positive individuals, presenting 2-4 weeks post-infection with asymmetric oligoarthritis, urethritis, and conjunctivitis/uveitis. [8]

9. Ciprofloxacin and azithromycin resistance is RISING GLOBALLY, particularly in S. sonnei from MSM networks. Culture and susceptibility testing is essential. [9,10,18]

10. Zinc supplementation (10-20 mg daily × 10-14 days) in children reduces diarrhoea duration and severity and is WHO-recommended. [20]

Classic Exam Scenario Stems

"A 2-year-old with bloody diarrhoea attends nursery where there is an outbreak..." → Shigellosis. Do NOT give loperamide. Culture stool, give azithromycin, notify public health.

"A traveller returns from South Asia with dysentery and develops oliguria, pallor, and petechiae 1 week later..." → HUS secondary to S. dysenteriae type 1. Check FBC (anaemia, thrombocytopenia), film (schistocytes), U&E (AKI), LDH (elevated). Manage supportively ± dialysis.

"An MSM patient with bloody diarrhoea; stool culture shows resistance to ciprofloxacin, azithromycin, and TMP-SMX..." → XDR S. sonnei. Treat with IV ceftriaxone. Partner notification. Public health alert.

"A child with shigellosis develops asymmetric knee and ankle arthritis 3 weeks after resolution..." → Reactive arthritis. Check HLA-B27. Treat with NSAIDs ± intra-articular steroids.

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16. References

Primary Guidelines

1. Kotloff KL, Nataro JP, Blackwelder WC, et al. Burden and aetiology of diarrhoeal disease in infants and young children in developing countries (the Global Enteric Multicenter Study, GEMS): a prospective, case-control study. Lancet. 2013;382(9888):209-222. PMID: 23680352

2. GBD 2016 Diarrhoeal Disease Collaborators. Estimates of the global, regional, and national morbidity, mortality, and aetiologies of diarrhoea in 195 countries: a systematic analysis for the Global Burden of Disease Study 2016. Lancet Infect Dis. 2018;18(11):1211-1228. PMID: 30243583

3. Bennish ML, Wojtyniak BJ. Mortality due to shigellosis: community and hospital data. Rev Infect Dis. 1991;13 Suppl 4:S245-251. PMID: 2047654

4. Bennish ML, Harris JR, Wojtyniak BJ, Struelens M. Death in shigellosis: incidence and risk factors in hospitalized patients. J Infect Dis. 1990;161(3):500-506. PMID: 2313130

5. DuPont HL, Levine MM, Hornick RB, Formal SB. Inoculum size in shigellosis and implications for expected mode of transmission. J Infect Dis. 1989;159(6):1126-1128. PMID: 2656880

6. World Health Organization. Guidelines for the control of shigellosis, including epidemics due to Shigella dysenteriae type 1. Geneva: WHO; 2005.

7. Ashkenazi S, Dinari G, Weitz R, Nitzan M. Convulsions in childhood shigellosis. Clinical and laboratory features in 153 children. Am J Dis Child. 1987;141(2):208-210. PMID: 3812389

8. Hannu T, Inman R, Granfors K, Leirisalo-Repo M. Reactive arthritis or post-infectious arthritis? Best Pract Res Clin Rheumatol. 2006;20(3):419-433. PMID: 16777575

9. Baker KS, Dallman TJ, Ashton PM, et al. Intercontinental dissemination of azithromycin-resistant shigellosis through sexual transmission: a cross-sectional study. Lancet Infect Dis. 2015;15(8):913-921. PMID: 25998316

10. Williamson DA, Outhred AC, Jennison AV, et al. Multidrug-resistant Shigella sonnei in Australia: public health surveillance and molecular epidemiology, 2001-2018. J Antimicrob Chemother. 2019;74(7):2007-2012. PMID: 30968151

Epidemiology and Transmission

11. Khalil IA, Troeger C, Blacker BF, et al. Morbidity and mortality due to shigella and enterotoxigenic Escherichia coli diarrhoea: the Global Burden of Disease Study 1990-2016. Lancet Infect Dis. 2018;18(11):1229-1240. PMID: 30266330

12. Williams PCM, Berkley JA. Guidelines for the treatment of dysentery (shigellosis): a systematic review of the evidence. Paediatr Int Child Health. 2018;38(sup1):S50-S65. PMID: 29877780

Pathophysiology

13. Phalipon A, Sansonetti PJ. Shigella's ways of manipulating the host intestinal innate and adaptive immune system: a tool box for survival? Immunol Cell Biol. 2007;85(2):119-129. PMID: 17213832

14. Killackey SA, Sorbara MT, Girardin SE. Cellular aspects of Shigella pathogenesis: focus on the manipulation of host cell processes. Front Cell Infect Microbiol. 2016;6:38. PMID: 27047801

15. Lobato-Márquez D, Xu J, Güler GÖ, et al. Mechanistic insight into bacterial entrapment by septin cage reconstitution. Nat Commun. 2021;12(1):4511. PMID: 34301939

16. Kühn S, Bergqvist J, Gil M, et al. Actin assembly around the Shigella-containing vacuole promotes successful infection. Cell Rep. 2020;31(4):107638. PMID: 32402280

Complications

17. Tarr PI, Gordon CA, Chandler WL. Shiga-toxin-producing Escherichia coli and haemolytic uraemic syndrome. Lancet. 2005;365(9464):1073-1086. PMID: 15781103

Antibiotic Therapy

18. Christopher PR, David KV, John SM, Sankarapandian V. Antibiotic therapy for Shigella dysentery. Cochrane Database Syst Rev. 2010;(8):CD006784. PMID: 20687081

Diagnostics

19. Buss SN, Leber A, Chapin K, et al. Multicenter evaluation of the BioFire FilmArray gastrointestinal panel for etiologic diagnosis of infectious gastroenteritis. J Clin Microbiol. 2015;53(3):915-925. PMID: 25588652

Adjunctive Therapy

20. Lazzerini M, Wanzira H. Oral zinc for treating diarrhoea in children. Cochrane Database Syst Rev. 2016;12:CD005436. PMID: 27996088

Post-Infectious Sequelae

21. Marshall JK, Thabane M, Garg AX, Clark WF, Salvadori M, Collins SM. Incidence and epidemiology of irritable bowel syndrome after a large waterborne outbreak of bacterial dysentery. Gastroenterology. 2006;131(2):445-450. PMID: 16890598

Vaccines

22. Mani S, Wierzba T, Walker RI. Status of vaccine research and development for Shigella. Vaccine. 2016;34(26):2887-2894. PMID: 26979135

Additional Resources

23. Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea. Clin Infect Dis. 2017;65(12):e45-e80. PMID: 29194529

24. Centers for Disease Control and Prevention. Shigella – Shigellosis. Available at: https://www.cdc.gov/shigella/

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances, local antimicrobial resistance patterns, and current guidelines. Always consult appropriate specialists and apply clinical judgment.