BACILLARY DYSENTERY diagnosis and treatment.pptx

Gi infection caused by shigella known as shigellosis or bacillary dysentery ,its lab diagnosis and treatment and comparison with amoebic dysentery

1. BACILLARY DYSENTERY Moderator: Dr. Dharmendra Rajpoot Assistant Professor Microbiology Department MGMMC Indore Presenter: Dr. Ananya Verma P. G Resident Microbiology Department MGMMC Indore

2. CONTENTS Bacillary Dysentery Definition Epidemiology Complications Prevention Treatment Pathogen Laboratory Diagnosis Macroscopy Microscopy Culture Serology Morphology Cultural characters Pathogenesis A case work-up...

3. Case The patient was a 4-year-old who presented to her paediatrician in early summer with a 3-day history of vomiting and bloody, mucus-flecked diarrhoea . She had several episodes of vomiting and approximately 10 bowel movements/day . Her bowel movements were described as painful , and the parents reported that the patient had moderate abdominal pain . She also had fevers to 40°C with chills. She had no recent travel or camping history, no recent change in diet, no one at home with a similar illness, and stool was guaiac positive and was sent for culture. Three days later the laboratory reported that a non-lactose-fermenting, nonmotile, H 2 S-negative organism was growing on MacConkey agar from the patient’s stool specimen. When the father was called, he reported that the diarrhoea had completely resolved.

4. What do you think she is suffering from? Bacillary Dysentery????

5. What is Dysentery? Dysentery is an infective disease of the large bowels . Characterised by frequent passing of blood and mucus in the stool along with tenesmus and severe abdominal cramps. WHO defines Dysentery as- any diarrheal episode in which the loose or watery stools contain visible red blood is known as dysentery.

6. What are the agents causing Dysentery? Bacteria Parasites Shigella sp. E.coli(STEC,EHEC,EIEC) Campylobacter jejuni Salmonella sp. Vibrio parahemolyticus Clostridium difficile E. h istolytica G.lamblia C.parvum I. belli

7. Clinical diagnosis of Bacillary Dysentery….. Bloody Diarrhoea Scanty stool, non offensive odor Tenesmus Diffuse abdominal pain Sudden onset Bacillary Dysentery

8. In our case, lab report says a non-lactose-fermenting, nonmotile, H2S-negative organism was growing on MacConkey agar Bacteria with similar characteristics are Shigella species Bacillary dysentery caused by Shigella is also known as SHIGELLOSIS .

9. Epidemiology WHO estimates that Shigella species cause at least 50% of the cases of bloody diarrhea in young children in developing countries. Responsible for >80 million cases of bloody diarrhea and 700,000 deaths/year worldwide. Infections by S.dysentriae are more severe, found in tropical countries while S.sonnei causes mild infection and common in the western countries. Mortality is up to 20%. Antibiotic resistance to >2 drugs is common in international travellers.

10. Epidemiology Sources – Human only Transmission- Direct-human to human -Indirect –food, water, fomites Mode of infection- Ingestion. Infective Dose- 10-100 bacilli. Incubation period-2-5 days.

11. Classification of Shigella sp. Enterobacteriaceae Based on ‘O’ Antigen Shigella Species Subgroups Serotypes S. dysentriae Type- A 15 S. flexneri Type-B 08 9 subtypes S . boydi Type-C 19 S. sonnei Type-D 01

12. The CDC classification combines S. dysenteriae (group A), S. flexneri (group B), and S. boydii (group C) as “Shigella serogroups A, B, and C” because of their biochemical similarities. S. Sonnei β- galactosidase and Ornithine decarboxylase activity S. dysenteriae Inability to ferment Mannitol and a negative catalase reaction Isolates recovered from stool specimens from patients with diarrheal disease that are suspected of being Shigella species should be biochemically categorized and the species confirmed by serologic testing.

13. Morphology of Shigella sp. Facultative Anaerobes Gram Negative Bacilli Non motile Non Sporing Non capsulated

14. Virulence Factors… Invasion Toxin Through M cells Shigella invade the cells from the Basolateral sides by polymerization of Actin fibres Endotoxin Exotoxin Shiga toxin Inhibition of protein synthesis Cell death Alter the metabolic activity of intestinal epithelial cells Outpouring of electrolytes and fluid into the lumen Shigella Enterotoxin

15. Shigella enterotoxin ShET1 is structurally similar to cholera toxin and is found essentially in S.flexneri 2a . ShET2 is present in all S. flexneri isolates. It helps in iron uptake.

16. Pathogenesis …

17. BACTERIAL-INDUCED APOPTOSIS Shigella spp. provoke the death of macrophages by introducing the proteins IpaB into their cytoplasm IpaB Activate caspase-1 leading to Apoptosis Release of the proinflamm atory cytokines interleukin (IL)-1b and IL-18 Cytokines damages the colonic mucosa and exacerbates the infection. The genes for invasiveness are located on a large invasion plasmid . These activities lead to extensive super ficial tissue destruction. Dysentery

18. Shigella Mechanism of action of the shiga toxin. Binding of the bacterium to the gb-3 receptor on the cell. Production of the shiga toxin. (3) Stx is transported to the Golgi complex. (4) Endocytosis of the toxin in the cell. (5) Clathrin -enveloped vesicle formation. (6) The toxin is transported to the Golgi complex. (7) Vesicle breaking and separation of pentamer B from the toxic A1 fragment. (8) Action of the A1 portion on the rRNA in the 28S portion, acting as N- glyocsidase , replacing an Adenine moiety. (9) Protein synthesis inhibition. (10) Cell death

19. Pathogenesis … Shiga toxin of shigella dysenteriae chromosomally encoded . 2 subunits- A and B B binds to Gb3 glycolipid receptor on the surface of target cells. A- subunit prevents binding of aminoacyl -transfer RNA through cleavage of the 28S rRNA from 60S ribosomal subunit. Blocks protein synthesis.

20. Pathogenesis … Shigella infect the epithelial cells of colon and multiply inside them. They spread laterally into adjacent cells as well as to the lamina propria . Inflammatory reaction Necrosis of epithelial cells necrotic epithelium sloughed out Transverse Superficial Ulcers Virulence marker antigen (VMA) responsible for cell penetration. Shigella dysentriae type 1 exotoxin Toxaemia

21. Shigella dysenteriae Neuraminidase Degrades neuraminic acid ( sialic acid), an intercellular cement of the epithelial cells of the intestinal mucosa. Allows more bacteria to enter the cell.

22. Pathogenesis … All species of Shigella cause acute bloody diarrhea by invading and causing patchy destruction of the colonic epithelium. . Leads to the formation of ulcers and inflammatory exudates, and causes inflammatory cells and blood to appear in the stool. The diarrheal stool contains 10 6 to 10 8 shigellae per gram. Once excreted, the organism is very sensitive to environmental conditions and dies rapidly. Stool specimens submitted for culture should be processed rapidly or use a Transport Medium.

23. Lab diagnosis is essential for proper patient management, prevention & control . Transport Media Sach’s Buffered glycerol saline. Cary-Blair medium Should be collected in clean, wide-mouthed screw capped containers.

24. Amoebic dysentery vs Bacillary dysentery

25. Physiological characters of Shigella sp . Gram negative bacilli Catalase positive No H 2 S Producer Does not ferment lactose (except S. sonnei) Ferment Mannitol (except S. dysenteriae) Non motile

26. Lab Diagnosis…..On receiving sample Gross examination Microscopy Culture Serology Bright red Odourless Mucus flakes Scanty faeces Alkaline

27. Lab Diagnosis…..On receiving sample Gross examination Microscopy Culture Serology Few non motile bacteria, numerous pus cells RBCs , macrophages(with ingested RBCs).

28. Lab Diagnosis…..On receiving sample Gross examination Microscopy Culture Serology Isolation Identification

29. Lab Diagnosis…..On receiving sample Gross examination Microscopy Culture Serology Isolation Identification MacConkey XLD Agar DCA Translucent NLF Colonies Translucent Red without black centre Colonies

30. Biochemical reactions Catalase- Positive Oxidase- Negative Lactose- Negative Mannitol- Fermented Methyl Red – Positive Voges Proskauer- Negative Lysine decarboxylation- Negative H2S- Negative Indole V Citrate -ve Urease -ve TSI k/a

31. Differentiation of E. coli and Shigella

32. Differentiation of Species Within the Genus Shigella

33. Serological Identification Polyvalent somatic (O) antigen grouping Antisera Slide Agglutination test Followed by testing with monovalent antisera for specific serotype identification.

34. Subtyping A variety of methods have been used to subtype Shigella, including Colicin typing (particularly for S. sonnei) Plasmid profiling Restriction fragment length polymorphism analysis Ribotyping

35. Antibiotic Susceptibility & Treatment Severe Shigella infections require antimicrobial agents for treatment. Because of the widespread antimicrobial resistance among Shigella strains, all isolates should undergo susceptibility testing. Reporting of susceptibility results to the clinician is particularly important for S. dysenteriae 1 isolates because it is often acquired during international travel to areas where most strains are multidrug resistant. In many areas of Africa and Asia, S. dysenteriae 1 strains are resistant to all locally available antimicrobial agents, including ampicillin and nalidixic acid.

36. Treatment Shigellosis is self limiting disease. WHO recommended Ciprofloxacin as Ist line drug. Alternative drug- 3 rd generation cephalosporins Antibiotics are essential to, Eliminate the bacteria Reduce course of illness Reduce transmission

37. She was saved from complications … Arthritis Toxic neuritis Intussusception Microangiopathy Haemolytic uremic syndrome Thrombocytopenic purpura Sever toxaemia and death