Microbiological aspect of liver
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This document summarizes various microbial infections that can affect the liver, including bacterial, parasitic, fungal and viral infections. It describes the causative agents, modes of transmission, clinical manifestations and pathological changes involved in conditions like pyogenic liver abscess, amoebic liver abscess, schistosomiasis, hepatitis A-E and more. The liver is susceptible to microbial infections due to its role in filtering absorbed intestinal contents.
Microbiological aspect of liver
- 1. MICROBIOLOGICAL ASPECT OF LIVER DR.SAUMYA SINGH P.G 2ND YR MICROBIOLOGY Department dr.d.y.patil medical college kolhapur
- 2. The liver serves as the initial site of filtration of absorbed intestinal luminal contents and is particularly susceptible to contact with microbial antigens of all varieties. The liver can be affected by : (1) Spread of bacterial or parasitic infection from outside the liver; (2) Primary infection by Spirochetal, Protozoal, Helminthic, or Fungal organisms; (3) Systemic effects of bacterial or granulomatous infections. 4) Viruses
- 3. BACTERIAL INFECTIONS INVOLVING OR AFFECTING THE LIVER GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA
- 4. Pyogenic Liver Abscess Pyogenic liver abscess is a pus filled area within the liver. Causes: Infection in the blood( Hematogenous spread) Staphylococcus aureus or Streptococcus milleri. An infection of biliary tract ;enteric gram – bacilli and enterococci . Pelvic or colonic source: mixed flora incl. Aerobic and anaerobic especially B. fragilis.
- 5. Toxic Shock Syndrome It is a multisystem disease . Staphylococcus aureus or Group A Streptococci. Hepatic involvement - Jaundice and extensive necrosis. Toxic shock syndrome toxins (superantigens ) cause T cell activation and massive cytokine release.
- 6. Clostridial myonecrosis Clostridium perfringens Jaundice,abscess may develop. Exotoxin elaborated by the bacterium. Actinomycosis Actinomyces israelii Jaundice,abscess may develop. Metastatic spread from other abdominal sites.
- 7. Enteric fever Salmonella typhi Hepatic damage by S. typhi Mediated by bacterial endotoxin Mesenteric adenitis Yersinia enterocolitica The subacute septicemic form of the disease result in abscess.
- 8. Fitz hugh curtis syndrome Neisseria gonorrhae Hepatic complication of gonococcal infection. Perihepatitis- Direct spread of the infection from the pelvis. Brucellosis Brucella suis, Brucella abortus, Brucella melitensis,Brucella ovis Jaundice , hepatosplenic abscesses.
- 9. Melioidosis Burkholderia pseudomallei Multiple abscesses in liver. Q Fever Coxiella burnetii( obligate intracellular bacteria) (granulomatous) hepatitis.
- 10. Oroya Fever Bartonella bacilliformis Jaundice, hepatosplenomegaly and Centrilobular necrosis of the liver . Bacillary Angiomatosis Bartonella henselae, Bartonella quintana Peliosis hepatis or blood-filled cysts (immunodeficiency states). Infection frequently is associated with exposure to cats.
- 11. Ehrlichiosis Ehrlichia Chaffeensis, Ehrlichia Ewingii ( obligately intracellular pathogens belongs to rickettsiaceae family). Focal necrosis, fibrin ring granulomas, and cholestatic hepatitis. Liver injury is attributable to proliferation of organisms within hepatocytes and provocation of an immune response.
- 12. Leptospirosis Leptospira interrogans Icteric leptospirosis-hepatic involvement. Severe form with multi-organ involvement- Weil's disease. ( hepatorenal damage) Lyme Disease Borrelia burgdorferi(Tick-borne spirochete). Acute hepatitis as a manifestation of reactivation
- 13. Syphilis Treponema pallidium Hepatic lesions are common. Hepatic Tuberculosis Mycobacterium tuberculosis Mycobacterium avium intracellulare ( AIDS ) Tubercle bacilli reach the liver by way of hematogenous dissemination .
- 14. protozoa
- 15. Hepatic sinusoidal lymphocytosis (malaria) P. falciparum Mixed infection with P. vivax Repeated exposure to malaria (aberrant immunologic Response) Overproduction of B lymphocytes Circulating malarial antibody An increased levels of circulating immune complexes. Visceral leishmaniasis Leishmania donovani Infective form- flagellated promastigotes Hepatocyte necrosis Complications of chronic liver disease are rare.
- 16. Amoebic liver abscesses Entamoeba histolytica Infective form - cyst Definitive host - man Source of infection- cyst passing chronic patient or asymptomatic carrier. Mode of transmission-oral-fecal route Intestinal lesions can metastasize to various other organs,commonest being liver(hepatic amoebiasis). Necrosis of liver cells leading to abscess formation which is typical anchovy sauce in appearance.
- 18. Toxoplasmosis Toxoplasma gondii Primary host - cat Intermediate host - human Uptake of cyst by inhalation, followed by ingestion . Disseminated infection of liver occurs resulting in hepatomegaly.
- 19. Hyperinfection syndrome Strongyloides stercoralis Common - immunocompromised patients. Infective form - filariform larvae. Route of entry - intact skin,lungs,intestine. Dissemination of filariform larvae into tissues(liver) that usually are not infected.
- 20. Trichinosis Trichinella spiralis Mode of transmission - raw or undercooked pork bearing larvae Route - in the small intestine, penetrate the mucosa, and disseminate through the systemic circulation to other organs and liver resulting in jaundice.
- 21. Hepatic Capillarias Capillaria hepatica Mode of infection - ingesting soil, food, or water contaminated with embryonated eggs. Larvae released in the ceacum penetrate the intestinal mucosa, enter the portal venous circulation, and lodge in the liver. Adult worms disintegrate, releasing eggs into the hepatic parenchyma and producing an intense inflammatory reaction.
- 22. Ectopic Ascariasis Ascaris lumbricoides Mode of infection - contaminated food ,drink or fingers. Definitive host - man Infective agent - embryonated egg Site of localisation - small intestine Migration of adult worm to liver causes liver abscess
- 23. Viseral larva Migrans Toxocara canis,Toxocara catis Mode of transmission - contaminated food or soil. Route of transmission - intestine,penetrate the wall ,carried in blood to liver forming nodules.
- 24. Echinococcosis (hydatid cyst) Echinococcus granulosus Definitive host - dog Intermediate host – man Mode of infection - contaminated food and drink Infective agent - embryonated eggs. The eggs hatch in the small intestine and liberate oncospheres that penetrate the mucosa and migrate via vessels or lymphatics to distant sites, liver being the most common destination (70%) and forms cyst known as hydatid cyst.
- 25. The early stage of infection is generally asymptomatic. As the cyst enlarges, symptoms of a space-occupying lesion develop. The great danger lies in the rupture of the cyst causing the escape of hydatid fluid and hydatid sand anaphylactic shock escaped protoscolices can form new hydatid cysts. E. multilocularis is highly invasive Infection leads to formation of solid masses in the liver . E. vogeli has clinical features intermediate between those of infections caused by the other two species and is characterized by multiple fluid filled cysts. Superinfection of the hepatic cysts can lead to pyogenic liver abscesses in up to 20% of patients with hepatic disease.
- 26. Schistosomiasis (Bilharziasis) Schistosoma mansoni, S. haematobium,S.japonicum. Infective form - cercariae Source of infection - contaminated freshwater Intermediate host-Snail Definitive host -humans Hepatic granulomas Its due to immunologic reactions to Schistosoma eggs trapped in tissues. Antigens released from the egg stimulate a granulomatous reaction involving T cells, macrophages, and eosinophils
- 27. Clonorchiasis Clonorchis sinensis Source of infection - raw or inadequately cooked fresh fish infected with metacercariae of clonorchis. Definitive host - man First intermediate host - snail Second intermediate host - crypinoid fish Hepatic parenchymal damage
- 28. Fasciolosis Fasciola hepatica,Fasciola gigantica Definitive host - humans Intermediate host - freshwater snails Infective form - metacercaria Reservoir host - sheep Source of infection - raw aquatic vegetation contaminated with encysted metacercaria such as lettuce and green salad. Painful enlargement of liver, obstruction and inflammation of bile duct .
- 29. Fungal diseases
- 30. Disseminated Candidiasis Candida species Predisposing factor - immunocompromised persons,leukemic patients undergoing high-dose chemotherapy. Hepatic involvement.
- 31. Disseminated histoplasmosis Histoplasma capsulatum Portal of entry - respiratory tract . Predisposing factor- Severely immunocompromised persons . The liver can be invaded in both acute and chronic progressive disseminated histoplasmosis
- 32. Viruses
- 33. Hepatitis A RNA Virus Source of infection - Faeces Route of transmission - Fecal-oral Infects the liver, causing inflammation. Although it may cause acute symptoms, it rarely results in severe or chronic liver disease.
- 34. Hepatitis B DNA Virus Source of infection-Blood/blood derived body fluid Route of transmission- : parenterally, low vertical and sexual transmission Hepatocellular necrosis occurs due to the body’s reaction to the virus rather than due to the virus itself
- 35. Hepatitis C (the silent epidemic) RNA virus Source of infection-Blood/blood derived body fluid Route of transmission- Parenterally, low vertical and sexual transmission Cirrhosis Hepatocellular carcinoma
- 36. Hepatitis D Defective virus which requires hepatitis B as a helper virus in order to replicate. Infection therefore only occurs in patients who are already infected with hepatitis B. Increased severity of liver disease in hepatitis b carriers.
- 37. Hepatitis E RNA virus similar to hepatitis A Source of infection - faeces Route of transmission-Fecal-oral Cause of enterically transmitted non-a,non-b hepatitis(acute). Fulminant hepatitis in pregnant women. Hepatitis G RNA virus 0.2% acute hepatitis Exact role not known, probably not a pathogen