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MLT-Enterobacter
Microbiology
Question | Answer |
---|---|
Growth medium for Enterobacteriaceace? | Good growth on MacConkey agar |
Characteristics of Enterobacteriaceace? | Oxidase -ve Catalase +ve Fermentative +ve Nitrate reductase +ve |
What are the opportunistic pathogens? | Klebsiella, Proteus, Citrobacter, Enterobacter affected category: immunocompromised patient |
What are the primary pathogens? | Salmonella, Shigella, Yersinia, E.coli |
Types of Salmonella? | total 2500 species S.typhi, S. paratyphi A,B&C: cause Typhoid Fever Other Salmonella species: cause diarrhoea |
Types of Shigella? | total 4 species Sh. dysenteriae causes dysentery (bloody diarrhoea) other 3 species: Sh. flexneri , Sh. boydii & Sh.sonnei diarrhoea |
Types of Yersinia? | total 11 species Y. enterocolitica causes gastro intestinal infection Y. pestis dangerous pathogen causing plague (“Black death”) Transmitted by flea bite |
Types of E.coli? | E. coli on MacConkey agar pink/magenta colonies Pathogenic E. coli: Enteropathogenic E. coli Enterohaemorrhagic E. coli (O157:H7) Enterotoxigenic E. coli Enteroinvasive E. coli Enteroaggregative E. coli |
How does Enteropathogenic E.coli work? | Intimate adhesion. Attach to villi, damage intestinal epithelium by adhesion. Associated with infantile diarrhoea. |
How does Enterotoxigenic E.coli work? | Produce 2 types of enterotoxins : heat labile toxin & heat stable toxin. Associated with traveller’s diarrhoea. |
How does Enteroinvasive E.coli work? | Intimate Adhesion. Damage by invasiveness. Phagosome lyses, intracellular movement , lateral spread to other cell. Watery diarrhoea with mucus & may be bloody. |
How does Enteroaggregative E.coli work? | Aggregate adhesion in mucus, deliver toxin. Causes diarrhoea at all ages. |
How does Enterohaemorrhagic E. coli (O157:H7) work? | Intimate adhesion, deliver Shiga toxin. Damage intestinal epithelium by adhesion. Produce cytotoxin (Shiga toxin), causes bloody diarrhoea , renal failure |
Types of Klebsiela spp.? | 7 species identified, Kleb . pneumoniae is the most important species. Causes UTI, RTI, septicaemia , etc , an important nosocomial pathogen. Colonies are large, mucoid and viscous. |
Types of Proteus? | total 4 species. P. mirabilis & P. vulgaris are important. Produces swarming colonies on agar. |
Types of Enterobacter? | total 15 species. E. aerogenes and E. cloacae are most important. Causes UTI, RTI, septicaemia , etc , an important nosocomial pathogen. |
Types of Citrobacter? | total 11 species. 11 species, C. diversus (indole +ve ) & C. freundii (H 2 S +) are more common |