Gram Negative Rods (GIT)
Most common features of all the gram -ve rods of the enteric tract ( except P. aeruginosa )are i. Fcaultative anaerobes ii. ferment glucose iii. oxidase negative iv. reduce nitrates to nitrites.

E. coli ( GIT Module and KUB Module )

1. Most common cause of UTI (urinary tract infection).
2. major cause of traveler's diarrhea.
3. also cause neonatal meningitis
4. O157:H7 strain causes bloody diarrhea and hemolytic uremic syndrome.
5. Pathogenisis is mostly through enterotoxins

Labs:

1. Ferment lactose and form Pink colonies.
2. On EMB agar, form green sheen colonies.
3. E.coli O157:H7 doesnt ferment sorbitol.

Salmonella

1. common cause of typhoid fever (S.typhi).
2. causes enterocolitis.
3. animal source of salmonella is poultry and eggs.
4. S. typhi is transmitted only by humans. ( carrier rate is higher among women)

Labs: ( are important for exam and viva )

1. In typhoid fever rose spots may present on abdomens.
2. Widal test commonly used for detecting antibodies in patient serum.
3. Do not ferment lactose but produce H2S.