Whooping cough & cholera.pptx clinical microbiology

vibrio cholerae, pathogenesis, treatment and prevention in microbiology and Bordetella pertussis infection

1. Whooping cough & cholera

2. Bordetella pertussis

3. Gram negative coccobacillus . Disease: Whooping cough.

4. Pathogenesis & epidemiology: Only in humans. By airborne droplets. Attachment to ciliated epithelium by filamentous hemagglutinin . Death of ciliated epithelium. Pertussis toxin induces lymphocytosis .

5. Clinical findings: Acute tracheobronchitis . Initially mild URT symptoms, followed by paroxysmal cough with copious mucus that end with an inspiratory ‘whoop’. Blood culture is negative. Leucocytosis . Death due to pneumonia.

6. Laboratory diagnosis: Nasopharyngeal swab. Culture in Bordet- Gengou medium. Identification: antiserum or flourescent antibody. PCR. Serology ,in difficult cases.

7. Treatment: Erythromycin Supportive care. Prevention: 2 vaccines. Acellular & killed. Erythromycin .

8. Vibrio cholerae

9. Vibrio cholerae By electron microscope (curved bacilli or coma shape)

10. V.cholerae is divided into 2 sero groups. (O1 & non-O1) O1 is divided into 2 biotypes: El Tor & classical biotypes. . & 3 serotypes Ogawa Inaba Hikojima For Epidemiologic investigations Vibrio cholerae

11. Transmission : fecal contamination of food & water , from human sources. Carriers =asymptomatic and convalescent pts. Animal reservoirs =marine shelfish (oysters & shrimp) Predisposing factor: Poor sanitation malnutrition overcrowding Quarantine failed to prevent spread of the disease.

12. Pathogenesis: Colonization (small intestine). 1 m illion must be ingested. Susceptibility : no stomach acid An enterotoxin ( choleragen ) causes outpouring of fluid, potassium & chloride into the lumen massive watery diarrhea. Mucinase mucus layer penetration.

13. Death : due to dehydration & electrolyte imbalance but With prompt treatment It is self limited (up to 7 days).

14. Clinical findings: Hallmark : watery diarrhea in large volumes (rice- water stool). Stool :no white or red blood cells. No abdominal pain. Symptoms due marked dehydration & electrolyte loss. Cardiac failure ,renal failure. Acidosis,hypokalemia (loss of bicarbonate, potassium) Mortality rate without treatment =40 %

15. Lab.diagnosis : Depends on the situation. In epidemics: clinical diagnosis. In endemic areas or to detect carriers: Stool sample. Gram negative,comma -shaped bacillus. Culture in a selective medium ( TCBS = T hiosulphate - C itrate- B ile salt- S ucrose agar) green in colour . The colonies are yellow.

16. Mac Conkey’s agar: colorless colonies (ferments lactose slowly). Oxidase + ve Presumptive diagnosis :by antisera. PCR .

17. Treatment: Prompt, adequate replacement of water & electrolytes. (orally or IV). Antibiotics not necessary, but they do shorten the duration & reduce excretion of organism.

18. Prevention: Mainly by public health measures (clean water & food supply). Vaccine : Killed vaccine plus subunit B. Another live vaccine recommended for travelers. Tetracycline for close contacts but does not prevent spread of an epidemic. Prompt detection of carriers .

19. End