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Colony Characteristics of Enterobacter Aerogenes

Enterobacter aerogenes is a rod-shaped bacterium that causes infections. They can be treatment-resistant although antibiotics are effective for most forms. They are responsible for a large number of infections in hospitals, particularly if the patient undergoes multiple surgical procedures or catheter changes or is experiencing a long hospital stay.

Motility
- Motility refers to a bacterium's ability to spread across a surface as opposed to being stationary in a colony. Enterobacter aerogenes do have motility and as such they can spread easily in environments like hospitals and can be picked up on various instruments. Enterobacter aerogenes do not produce spores.
Antigenic Structure
- Klebsiella is another another genus of Enterobacteriaceae and can be distinguished from Enterobacter aerogenes by the lack of presence or the H antigen. This can determine whether the body is motile or non-motile. Kebsiella is motile and contains the antigens O and K whereas Enterobacter aerogenes contain O, K and H antigens.
Non-Selective Media
- The type of growth media is a determinant of the colony characteristics of Enterobacter aerogenes. Non-selective media do not contain inhibitors that allow certain types of bacteria to grow. If Enterobacter aerogenes is grown in non-selective media it forms smooth, moist, grey colonies.
Selective Media
- MacConkey agar is an example of selective media because it contains lactose as well as a pH indicator that turns red with the presence of acid. Enterobacter aerogenes, when grown on this type of selective media, grows into pink or red colonies because they ferment with lactose and become acidic. This allows them to be differentiated from other bacteria that do not ferment lactose.

Nature