Table of Contents
What Agar does Enterobacter aerogenes grow on?
MacConkey agar
On MacConkey agar, E. cloacae and E. aerogenes commonly appear as pink, lactose-fermenting, mucoid colonies similar in appearance to Klebsiella pneumoniae and K.
What species can grow on mannitol salt agar?
Mannitol is the fermentable carbohydrate source, fermentation of which leads to acid production. Staphylococcus aureus grows on this medium and ferments mannitol to produce yellow colonies. Most coagulase negative species of Staphylococci and Micrococci do not ferment mannitol and grow as small red colonies.
What bacteria grows on MSA plates?
Mannitol Salt Agar (MSA) is a selective and differential medium. The high concentration of salt (7.5%) selects for members of the genus Staphylococcus, since they can tolerate high saline levels.
How can you tell the difference between E coli and Enterobacter aerogenes?
E. coli is indole-positive; Enterobacter aerogenes is indole- negative. Glucose is the major substrate oxidized by enteric bacteria for energy production. The end products of the oxidation process vary depending on the specific enzymatic pathways in the bacteria.
Does E coli grow on MSA?
The MSA agar will retain its initial red color and will not change to yellow. Gram-negative bacteria like E. coli and P. aeriginosa are not tolerant to salt (not halophilic) and will not grow colonies on MSA (see quadrants II and IV).
What can grow on MSA plates?
Mannitol Salt Agar (MSA) This is a medium that is both selective and differential. The high salt concentration (7.5%) is the selective ingredient. Staphylococcus species, which commonly inhabit human skin, can grow on this high salt concentration (left plate in picture below).
Is E. coli lactose positive?
Background. E. coli are facultative anaerobic, Gram-negative bacilli that will ferment lactose to produce hydrogen sulfide. Up to 10% of isolates have historically been reported to be slow or non-lactose fermenting, though clinical differences are unknown.
How to identify Enterobacter aerogenes by microbiology?
Then it was incubated at 37 degree Celsius for 2 days, the result obtained was colonies grown of one kind only, when gram stained found out to be pink color rod shaped microbes, this proofed that it was a gram negative bacteria, but failed to obtain the gram positive colonies to grow on the agar plate.
Can a Gram positive bacteria grow on a MSA plate?
The isolation from the original test tube did not show a Gram positive bacterium so it was streaked onto an MSA plate which inhibits growth of Gram negative bacteria. The bacterium grew and the test was positive so a Gram stain was performed to determine if this was truly Gram positive or if the Gram negative continued to grow.
In actuality, research shows that “E. aerogenes is more related to Klebsiella aerogenes (47-64%) than it is to E. cloacae (44%) (9). Different species of Enterobacter like E. cloacae are known to be found on a number of seeds and plants while E. sakazakii is commonly seen in infants who were given infant milk-based powder formulas (9).
What’s the difference between E cloacae and E aerogenes?
In other words, E. aerogenes resembles E. cloacae but the leusine decarboxylase test is positive and gelatin liquification is late. E. aerogenes is also, often times confused with Klebsiella aerogenes. However, E. aerogenes is motile and urease negative while K. aerogenes is nonmotile and urease positive (5).