L5 Invasive Enteritis 2 PDF

Invasive Enteritis and systemic infections: Four clinical syndromes, plus the carrier state, are associated with the genus Salmonella. 1-Gastroenteritis (non-invasive): watery diarrhea caused by Salmonella enterica Subspecies enterica. 2-Particular organ systems infection: Osteomyelitis in sick...

Invasive Enteritis and systemic infections: Four clinical syndromes, plus the carrier state, are associated with the genus Salmonella. 1-Gastroenteritis (non-invasive): watery diarrhea caused by Salmonella enterica Subspecies enterica. 2-Particular organ systems infection: Osteomyelitis in sickle cell diseased patients caused by Salmonella typhimurium. 3-Vascular endothelium focal infection: -Some toxigenic serovars of Salmonella typhimurium. 4-Typhoid fever: -Serovars Salmonella typhi and paratyphi A and B. N The genus Salmonella is a large diverse group with serological varieties (Serovars). The main antigens that distinguish Salmonella serovars are: 1-The Somatic O antigen. 2-The Flagellar H antigen. 3-The Capsular K antigen. N Typhoid and paratyphoid fever: caused by: 1-Salmonella enterica : subspecies: typhi 2- Salmonella enterica : subspecies: paratyphi. Reservoir: Human only; no animal reservoirs. Transmission: -Fecal-Oral route from human carriers. -Contaminated food. Pathogenesis of Salmonella in Typhoid fever: Pathogenic dose: -107-108 CFU/ml in normal persons (due to gastric acid effect). -106 CFU/ml in patients with hypochlorhydria. Incubation period: from 5 to 21 days. Pathogenesis: -The microbes successfully escape being killed in the stomach. -Fimbrial and non- Fimbrial adhesion to ileocecal region. -Invasion of Microfold cells in the ileum mucosa.  -Salmonella pathogenicity island 1 gene; Vi antigen N (capsule). -Engulfment by dendritic cells ; Salmonella remain within vesicles; because its resistance ability to lysosomal contents due to anti-phagocytic capsule (Vi antigen). -In the sub-mucosal layer, The dendritic cell will carry the microbes to mesenteric lymph nodes (week-1). -Then to blood (primary bacteremia) ; (End of week-1 & week-2). n At the End of Week-2 and Week-3: -Multiplication in macrophages of RES Reticuloendothelial system; liver (hepatitis), spleen, and bone marrow. At the End of Week-3: -Secondary continuous bacteremia; Septicemia. -Appearance of signs and symptoms; daily high fevers that continue for 4 to 8 weeks in untreated cases. -Invasion of gallbladder and kidney ; Cholecystitis and nephritis respectively.  n -Gallstones explain the presence of carrier state. stones gallbladder doe to bretain remains in framGB SI - -Bile; release of microbe in small intestine; inflammation and ulceration of Peyer’s patches (End of Third week) -Diarrhea; hemorrhagic ulceration of mucosa. ? (immune-mediated destruction of Peyer’s patches). Diagnosis of Typhoid fever: Week-1: -Gradual increase in body temperature. -Relative bradycardia and headache. -Constipation mainly or diarrhea (sometimes). Week-2: -Persistent fever (unresponsive to antipyretics). -Stepladder fever. -Rose-colored skin spots (exanthem) in 30% of cases; (could seen at end of week-1).  Diagnosis of Typhoid fever: n Week-3: -Clinical features of week-2 -Fever that continue for 4 to 8 weeks in untreated cases (Stepladder fever), hepato-splenomegaly (Liver function test). -Gastrointestinal ulceration with bleeding (bloody diarrhea); perforation: bacterial peritonitis. -Renal disease ; nephritis, and other sepsis, meningitis(rare). (Kidney function test, urine culture). Typhoid fever: N Prognosis: mortality rate without treatment ≈ 20%. Complications: 1-Chronic carrier in gall bladder and urinary bladder 2-Perforation and peritonitis 3-Osteomyelitis 4-Septicemia Laboratory diagnosis of Typhoid fever: Direct: Microbiology: Clinical specimens: Blood, stool, urine culture. -At week number one: 80% show positive blood Culture, Leukopenia -Bone marrow positive culture. -By week number 3: 85% of stool culture are positive. Widal test positive. –Urine culture. - Blood culture: A 3 to 8 ml should be cultivated in blood culture bottle. N Growth indications: Turbidity, Hemolysis, and air bubbles. Subculture: - Non-lactose fermenter, H2S producers. (see lecture-4) - Serotyping by Salmonella polyvalent reagent. N Indirect: Serology: Widal test: ( Positive: In Week 3): -Detection of Anti-Salmonella Antibodies in patient sera. -Significant titer: 1/160 or more for O antigen. Antigens: 1-Salmonella typhi O. 3-Salmonella paratyphi A and B O. 2-Salmonella typhi H. 4-Salmonella paratyphi A and B H. n Treatment: -Started with injectable ciprofloxacin or third generation cephalosporin, sensitivity results should be seen. -Chronic carriers: ciprofloxacin and cholecystectomy in the case of failure. Vaccination: Injectable: killed vaccine or capsular Vi antigens. Oral vaccine: live attenuated. Malta fever :( undulant fever): (Brucellosis): The Genus : Brucella : Zoonotic disease. Brucella abortus: cattle. Brucella melitensis: goats, Transmission: Unpasteurized milk or milk products. Direct contact with the animal. Incubation period: five days to several months Microbiology: -Small Gram-negative rods, Coccobacilli arranged singly or in pairs. -Non-capsulated, Non-motile.  Pathogenesis:. N Attachment to intestinal microvillus. Engulfed by intestinal macrophage. Infects the lymph nodes. Infects the RES, causing septicemia (endotoxin production). Could be complicated with Granulomatous response with central necrosis, if untreated. N Symptoms of Brucellosis: SDL Acute septicemia: ???? fever. malt fevers , high free Liver: ????. hepatomegaly Acute septicemia: night sweat, joints pain, anorexia, weight loss. Chronic: symptoms for ≥ a year with localized infection ?????: ostomylitis , endocarditis , pyleonephritis lorgan dependent It cause abortion and miscarriages in pregnant ladies. A cause of fever of unknown origin (PUO). n Diagnosis: Specimens: bone marrow aspiration, blood, liver biopsy and serum. Direct: culture: biphasic (solid and liquid) Castaneda media (7-21 days incubation) or automated system (3 days). Sub-culture from Blood culture: -Aerobic; grow best on liver extract agar. -5-10% CO2 for primary isolation. N Indirect: Serology: Agglutination Brucella test. -Significant titer: 1/80 to 1/160 -False negative reaction due to prozone phenomena. Yersinia enterocolitica and Yersinia pseudotuberculosis: -Invasion of terminal ileum, necrotic lesions of peyer patches. -Engulfed by dendritic cells; Invasion of mesenteric lymph nodes , and Lymphadenopathy. Microscopy and Cultural characteristics: n -Gram-negative short coccobacilli. 0 -Motile when grown at 25C, but not motile at0 - 37C. -Cold growth ( grow well at room temp.) Diagnosis: Direct: Blood culture. Indirect: Serology: Detection of Anti-Yersinia Antibodies in sera. References: 1-Schaechter’s Mechanisms of Microbial diseases, Fifth Edition: Chapter 17: Page 213- Page 219. 2-Lippincott’s Microbiology, Third Edition by Cynthia et. al: Chapter 12: page 116, and 117. -For Laboratory diagnosis of typhoid fever. -For Brucellosis: Chapter 13: page 139-141.