Enterobacter aerogenes, also known as Aerobacter aerogenes, is a member of the Enterobacteriaceae family. This family includes E coli, salmonella, shigella and klebsiella. Enterobacter aerogenes primarily causes nosocomial infections, being passed from one compromised patient to another.


Enterobacter aerogenes is a gram-negative (stains pink with the gram stain) bacteria. It is a small, rod-shaped bacteria that grown in smooth, round, white colonies. It is sometimes, but not always, a motile bacteria. Enterobacter aerogenes is a ubiquitous bacteria in the environment, found naturally in soil, fresh water, vegetables and human and animal feces.

Disease Presentation

Enterobacter aerogenes can cause infections in many parts of the human body. It is often a cause of lower-respiratory infections, including pneumonia. It may also cause urinary tract infections and infections of the skin and underlying tissues. It may present as cellulites, fasciitis, abscesses or post-operative wound infections. If the bacteria reach the blood (bacteremia), it can lead to sepsis. Rarely, the bacteria enters the cerebrospinal fluid, leading to meningitis. Enterobacter aerogenes overall has a low mortality rate (10.2 percent), with underlying medical issues increasing the risk of death.

Risk Factors

Enterobacter aerogenes is an opportunistic pathogen. Most individuals who develop an infection have an existing medical condition that makes it easier for the bacteria to grow and spread. Enterobacter aerogenes is frequently a hospital-acquired infection, especially of patients in the intensive-care unit or on mechanical ventilators. Other risk factors for infection include prior antibiotic use (this may reduce naturally occurring bacteria that compete with Enterobacter aerogenes), IVs or central lines, and burns. Enterobacter aerogenes more frequently affects newborns and the elderly. The bacteria are often part of a polymicrobial infection, sharing an infection site with other species of bacteria.


Antimicrobial treatment is appropriate for almost all infections with Enterobacter aerogenes. Beta-lactams, fluoroquinolones, aminoglycosides and TMP-SMZ can all be effective treatments. Most strains of the bacteria are resistant to one or more of these potential treatments, so the organism must be typed and tested for susceptibility before treatment begins.

Antibiotic Resistance

Resistance to beta-lactams is common, as beta-lactamase production (an enzyme that breaks down beta-lactams) can be induced in bacteria exposed to these antibiotics. Enterobacter aerogenes also commonly develops resistance to first-, second- and third-generation cephalosporins during treatment.