Pathogen Series | No. 01
Acinetobacter baumannii, Carbapenem-resistant
Environmental Persistence, Healthcare Significance
and the Role of UV Disinfection
Acinetobacter baumannii is a gram-negative bacillus and an opportunistic pathogen. It has a high infection rate amongst immunocompromised individuals, particularly those who have experienced a prolonged greater than hospital stay. It has been recognized to cause infections such as pneumonia, septicaemia, meningitis, urinary tract and wound infections, and is associated with high mortality. It is commonly associated with wet environments and is known to colonize the skin as well as being isolated in high numbers from the respiratory and oropharynx secretions of infected individuals. In recent years, it has been designated as a “red alert” human pathogen because of its extensively antibiotic resistance spectrum.
This organism is resistant to most first line antibiotics and increasingly resistant to many of the other broad spectrum antibiotics used to treat sepsis and other serious infections. Many of the resistance mechanisms have been ac quired from other organisms and are held on plasmids (extra chromosomal DNA). The most common mechanism of resistance of Acinetobacter baumannii is to β-lactams caused by its hydrolysis by the enzymes β-lactamases; all of the four Ambler classes of these enzymes have been described in this organism. In addition, the organism carries plasmids which confer resistance to quinolones, tetracy clines, macrolides, aminoglycosidesvia enzymatic or non- enzymatic pathways including changes in outer membrane proteins and multidrug efflux pumps. These plasmids are often held together in the same position on the plasmid and can be transferred into other species.
Although A.baumanii is multiply antibiotic resistant, it is not resistant to UV-C light and responds as any other Gram negative bacterium.
Moubareck CA and Halat DH (2020) Insights into Acinetobacter baumannii: A Review of Microbiological, Virulence, and Resistance Traits in a Threatening Nosocomial Pathogen Antibiotics 2020, 9, 119-148. Howard A, O’Donoghue M, Feeney A and Sleator RD (2012) Acinetobacter baumannii An emerging opportunistic pathogen Virulence. 3;: 243–250.
Vipin K. Rastogi, PhD, Lalena Wallace, MS, Lisa S. Smith, MS, Disinfection of Acinetobacter baumannii-Contaminated Surfaces Relevant to Medical Treatment Facilities with Ultraviolet C Light, Military Medicine, Volume 172, Issue 11, November 2007, Pages 1166–1169, https://doi.org/10.7205/MILMED.172.11.1166
Pathogen Size
0.9 - 1.6 μm
General Description
Gram negative bacillus (rod shaped)
Infection Risk From Environment
HIGH
Survives On Surfaces
3 days - 5 months*
Frequently Isolated From
Augmented Care Units
UV Relevence
Acinetobacter baumannii is widely referenced in published UV-C disinfection research because of its clinical importance and environmental persistence. The organism is also included within BS 8628 as one of the representative microorganisms considered when evaluating the microbiological performance of automated whole-room UV disinfection systems. While published studies demonstrate susceptibility to UV-C under controlled conditions, real-world performance depends on many operational factors including device positioning, shadowing, exposure time and surface accessibility.
Further Reading
* Kramer, Schwebke & Kampf (2006) Kramer A, Schwebke I, Kampf G. How long do nosocomial pathogens persist on inanimate surfaces? A systematic review. BMC Infectious Diseases. 2006;6(1):130. doi: 10.1186/1471-2334-6-130
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