بسم الله الرحمن الرحيم

1. بسم الله الرحمن الرحيم

2. Non Lactose-Gram Negative Bacilli Dr. Manal El Said Ass. Prof. of Medical Microbiology

3. Salmonella typhi Diseases Typhoid fever. Characteristics • Facultative gram-negative rods. • Non–lactose-fermenting. • Produces H2S. Habitat and Transmission • Habitat is the human colon only. • Transmission is by fecal–oral route.

4. Salmonella typhi Pathogenesis • Infects the cells of the reticuloendothelial system, especially in the liver & spleen. • Endotoxinin cell wall causes fever. • Capsule (Vi antigen) is a virulence factor. • Predisposing factors: • Decreased stomach acid resulting from ingestion of antacids or gastrectomy. • Chronic carrierstate established in gallbladder. • Organism excreted in bilefecal–oral spread to others.

5. Salmonella typhi Pathogenesis

6. Salmonella typhi Laboratory Diagnosis • Gram-stained smear and culture. • Non–lactose-fermenting colonieson MacConkey's agar. The used media selective for Salmonella are SS agar, bismuth sulfite agar, Hektoen enteric (HE) medium, brilliant green agar & xylose-lisine-deoxycholate (XLD) agar. They contain both selective and differential ingredients

7. Salmonella typhi Laboratory Diagnosis • TSI agar shows alkaline slant and acid butt, with no gas and a small amount of H2S.

8. Salmonella typhi Laboratory Diagnosis • Biochemical and serologic reactions used to identify species. • Identity by using known antisera against O, H, & Vi antigens . • Widal test detects agglutinating antibodies to O & H antigens in patient's serum, but its use is limited.

9. Salmonella typhi Treatment • Most effective drug is ceftriaxone. • Ampicillin & trimethoprim-sulfamethoxazole can be used in patients who are not severely ill. • Resistance to chloramphenicol & ampicillin is mediated by plasmid-encoded acetylating enzymes and β-lactamase, respectively.

10. Salmonella typhi Prevention • Public health measures: • - Sewage disposal • - Chlorination of the water supply • - Stool cultures for food handlers • - Handwashing prior to food handling. • Two vaccines are in common use: • - one vaccine contains purified Vi polysaccharide capsule • - other vaccine contains live attenuated S. typhi

11. Salmonellaenteritidis (Salmonella enterica) Diseases • Enterocolitis. • Sepsis with metastatic abscesses. Characteristics • Facultative gram-negative rods. • Non–lactose-fermenting. • Produces H2S. • Motile.

12. Salmonellaenteritidis (Salmonella enterica) Habitat and Transmission • Habitat is the enteric tract of humans &animals, e.g., chickens & domestic livestock. • Transmission is by the fecal–oral route. Pathogenesis • Invades the mucosa of small & large intestines. • Enter blood sepsis. • Infectious dose is at least 105 organisms because organism is inactivated by stomach acid. • Endotoxin in cell wall. • Predisposing factors: lowered stomach acidity from antacids or gastrectomy.

13. Salmonella enterica ssp. enterica on Salmonella Shigella (SS) Agar . Lactose negative, H2S positive colonies. Salmonellaenteritidis (Salmonella enterica) Laboratory Diagnosis • Gram-stained smear and culture. • Non–lactose-fermenting colonies on MacConkey's agar. Lactose positive colonies of Klebsiella pneumoniae (larger) and lactose negative colonies of Salmonella enterica ssp.enterica on McConkey agar.

14. Salmonellaenteritidis (Salmonella enterica) Laboratory Diagnosis • TSI agar shows alkaline slant & acid butt, with gas & H2S.

15. Salmonellaenteritidis (Salmonella enterica) Laboratory Diagnosis • Biochemical & serologic reactions used to identify species. • Antisera is used to identify by using known in agglutination assay. • Widal test detects antibodies in patient's serum to the O and H antigens of the organism but is not widely used.

16. Salmonellaenteritidis (Salmonella enterica) Treatment • Antibioticsnot recommended for uncomplicated enterocolitis. • Ceftriaxone are used for sepsis depending on sensitivity tests. • Resistance to ampicillin and chloramphenicol is mediated by plasmid-encoded β-lactamases & acetylating enzymes, respectively.

17. Salmonellaenteritidis (Salmonella enterica) Prevention • Public health measures • Do not eat raw eggs or meat. • No vaccine is available.

18. Shigella Species (e.g., S. dysenteriae, S. sonnei) Diseases Enterocolitis (dysentery). Characteristics • Facultative gram-negative rods. • Non–lactose-fermenting. • Nonmotile

19. Shigella Species (e.g., S. dysenteriae, S. sonnei) Habitat and Transmission • Habitat is the human colon only • No animal carriers • Transmission is by the fecal–oral route. Pathogenesis • Invades the mucosa of the ileum and colon sepsis (rare) • Endotoxin in cell wall. • The infectious dose ofShigellais low (1–10 organisms) because it is resistant to stomach acid. • Children in mental institutions & day care centers experience outbreaks. • No chronic carrier.

20. Shigella Species (e.g., S. dysenteriae, S. sonnei) Laboratory Diagnosis • Gram-stained smear and culture. • Non–lactose-fermenting colonies on MacConkey's agar. colonial morphology displayed by Shigella cultivated on a Hektoen enteric agar . Fecal flora with Shigella on MacConkey Agar Plates

21. Shigella Species (e.g., S. dysenteriae, S. sonnei) Laboratory Diagnosis • TSI agar shows an alkaline slant with an acid butt and no gas or H2S. • Identified by: • - biochemical reactions - serology with anti-O antibody.

22. Shigella Species (e.g., S. dysenteriae, S. sonnei) Treatment • Fluid & electrolyte replacement. • In severe cases, ciprofloxacin. • Resistance is mediated by : • -Plasmid-encoded enzymes: ß-lactamase degrades ampicillin • -Mutant pteroate synthetase sensitivity to sulfonamides . Prevention • Public health measures. • No Prophylactic drugs. • No vaccine.

23. Proteus Species Dr. Manal El Said Head of Medical Microbiology Department

24. Proteus Species (e.g., P. vulgaris, P. mirabilis) Diseases • UTI • Sepsis Characteristics • Facultative gram-negative rods. • Non–lactose-fermenting. • Highly motile. • Produce urease.

25. Proteus Species (e.g., P. vulgaris, P. mirabilis) Habitat and Transmission • Habitat is the human colon & environment (soil & water). • Transmission to urinary tract is by ascending spread of fecal flora.

26. Proteus Species (e.g., P. vulgaris, P. mirabilis) Pathogenesis • Endotoxin causes fever and shock associated with sepsis. • Urease degrades urea to produce ammonia Ph. • This leads to stones • - Obstruct urine flow • - Damage urinary epithelium • - Serve as a nidus for recurrent infection (trapping • bacteria within the stone. • Organism is highly motile facilitate entry into bladder. • Predisposing factors are: • -Colonization of the vagina • -Urinary catheters • -Abnormalities of urinary tract (strictures, valves & stones)

27. Proteus Species (e.g., P. vulgaris, P. mirabilis) Laboratory Diagnosis • Gram-stained smear and culture. • Swarming (spreading) effect over blood agar plate as the organism's active motility. • Non–lactose-fermenting colonies on MacConkey's agar. • Produces urease • P. mirabilis is indole-negative

28. Proteus Species (e.g., P. vulgaris, P. mirabilis) Laboratory Diagnosis • TSI agar shows an alkaline slant and acid butt with H2S.

29. Proteus Species (e.g., P. vulgaris, P. mirabilis) Treatment • Trimethoprim-sulfamethoxazole or ampicillin is often used for uncomplicated UTIs • A third-generation cephalosporin should be used for serious infections. • The indole-negative species P. mirabilis is more likely to be sensitive to antibiotics such as ampicillin. • Resistance is mediated by plasmid-encoded enzymes.

30. Proteus Species (e.g., P. vulgaris, P. mirabilis) Prevention • No vaccine or drug is available. • Prompt removal of urinary catheters helps prevent urinary tract infections.

31. Morganellamorganii & Providenciarettgeri • Enteric gram-negative rod similar to Proteus species. • Causes UTIs & sepsis. • Highly motile & produces urease. • Indole-positive and more resistant to antibiotics than P. mirabilis.

32. Yersiniapestis Diseases Bubonic & pneumonic plague. Characteristics • Small gram-negative rods with bipolar ("safety pin") staining. • One of the most virulent organisms (very low ID50) Habitat and Transmission • Reservoir is wild rodents, e.g. rats. • Transmission is by flea bite.

33. Yersiniapestis Pathogenesis • Virulence factors include: • Endotoxin • Exotoxin, • V & W proteins allow organism to grow within cells. • Envelope (capsular) antigen that protects against phagocytosis. Bubo is a swollen inflamed lymph node, located in the region of the flea bite

34. Yersiniapestis Laboratory Diagnosis • Gram-stained smear. • Wayson's stain show typical "safety-pin" appearance. • Cultures are hazardous & done only in specially equipped laboratories. • Organism is identified by immunofluorescence. • Serologic tests that detect antibody in patient's serum.

35. Yersiniapestis Treatment • Streptomycin either alone or in combination with tetracycline. • Strict quarantine for 72 hours Prevention • Control rodent & avoid contact with dead rodents. • Killed vaccine is available for high-risk occupations • Close contacts should be given tetracycline.

36. Yersiniaenterocolitica • Gram-negative rods. • It Causes: • -Enterocolitis (similar to Shigella & Salmonella). • - Mesenteric adenitis (mimic appendicitis) • Found in domestic animals • Transmitted by fecal contamination of food.