Introduction to Acinetobacter baumannii

Bacteria of the Acinetobacter genus are strictly aerobic and ubiquitous in the environment, with many species found in the soil and water. This step focuses on the species Acinetobacter baumannii as this bacterium has particular importance in human infections, especially in a hospital setting.

A. baumannii is a gram negative, aerobic bacterium which is rod-shaped and non-motile. Exhibiting pleomorphism, this bacterium can alter its morphology and functions to suit different environmental conditions.

A. baumannii infections

As mentioned in previous steps, A. baumannii – like other NFGNB – can colonise areas on/in the body (e.g. respiratory secretions) without causing infections. As an opportunistic pathogen, however, this bacteria can cause infections in patients with compromised immune systems – especially patients with prolonged length of in-hospital stay (LOS). Such infections include:

• Bloodstream infections

• Infections in battlefield wounds and some severe burns

• Prosthetic device-related infections

• Lung infections (pneumonia)

• Urinary tract infections

Management of infections caused by A. baumannii

Bacterial infections of this kind are generally treated with antibiotics, like with many other bacterial infections. The appropriate antibiotic(s) for the particular infection (and patient) will be determined by the results of laboratory antimicrobial susceptibility testing (AST) completed on samples collected from the patient.

With the Acinetobacter spp. largely resistant to many commonly-used antibiotics, however, the available pool of effective treatment is gradually decreasing, and compassionate uses of novel therapies are often sought.

This infographic produced by the CDC highlights the urgent threat to health posed by carbapenem-resistant Acinetobacter.