Gram Negative Bacilli
A specimen of thick, bloody sputum from a hospitalized 80-year-old patient with diabetes mellitus and difficulty in breathing is sent for laboratory analyses. The tests yield heavy growth of a lactose-positive, nonmotile, gram-negative rod with a large capsule. Which of the following bacteria is most likely to be the cause of the pulmonary problems?
a. Patients with K. pneumoniae infections usually have predisposing conditions such as alcoholism, advanced age, chronic respiratory disease, and diabetes. The "currant-jelly" sputum distinguishes K. pneumoniae from the other organisms. Infections can lead to necrosis and abscess formation.
b. Whereas all of the above listed organisms are gram-negative rods, only Klebsiella pneumoniae fulfill all of the laboratory criteria listed in the question, such as the presence of a very large capsule, which gives a striking mucoid appearance to its colonies, lactose fermenting, non-motile gram negative bacillus.
EXTRA EDGE OF Diarrheagenic E. Coli
ETEC - Heat stable toxin - ↑ c-GMP
- Heat labile toxin - ↑ c-AMP } Causes traveler’s diarrhea
[It produces cholera like toxin (cholera infantum), Biken test+]
EPEC - Attaches to enterocytes (enteroadherent) &destroy brush border villi.
Inflammation causes infantile diarrhea (remember EPEC affects pediatric population
EIEC - Only E – coli which invades G.I. mucosa (Enteroinvasive) & produces dysentery
likely disease ( DISEASE resembles shigella )
EHEC /VTEC - Produces verotoxin (shiga like toxin) which acts on vascular endothelium &
causes hemorrhagic colitis + HUS (strain H : 157 )
- Does not ferment sorbitol (sorbitol -)