Acinetobacter – Emerging Bacterial Pathogen
A Commensal Bacterium now Considered a Serious Infectious Agent
Oct 23, 2008
Acinetobacter baumannii is ubiquitous in nature, found in locations such as the human skin, throat and faeces, foodstuffs, soil and water. It is also increasingly isolated from the hospital environment, sometimes as antibiotic resistant strains, where it can cause problematic and serious infections.
Infections Caused by an Opportunistic Pathogen
Acinetobacter baumannii is a strictly aerobic, non-fermenting, oxidase negative, catalase positive, Gram-negative coccobacillus, growing as diploid or variable chain lengths forms. Until the 1980s, A. baumannii was considered to be a low grade, commensal organism that at worst was a potential opportunistic pathogen and as such often ignored by clinicians.
It is now clearly recognized as a cause of human infections, which can be severe and occasionally fatal, particularly in intensive care units which are much more frequent in modern hospitals. In the August 2008 International Journal of Antimicrobial Agents, Helen Giamarellou and co-researchers highlighted the particular importance of Acinetobacter as the cause of ventilator-associated pneumonia, and bacteraemia which although uncommon can lead to septic shock.
Antibiotic Resistant Acinetobacter Strains
The capacity of Acinetobacter to survive for extended periods on dry surfaces and its ability to become or multiply antibiotic resistant has resulted in it becoming endemic in many hospitals. As one of a growing number of antibiotic resistant bacteria, it is essential that a regime of infection prevention is practiced, through rigorous hospital cleaning and meticulous personal hygiene to halt the spread of these lethal strains.
Some microbiologists have suggested that analyses of resistance patterns in A. baumanni have indicated that antibiotic treatment options are closer to exhaustion than even for MRSA strains of Staphylococcus aureus.
Acinetobacter Grows in Alcohol Hand Wash Gel
Recently, there has been controversy over the possible proliferation of A. baumanni where alcohol-containing hand wash gels are used, especially in hospitals and other clinical environments. The bacterium is able to utilize alcohol as a growth substrate and so it might multiply where residues of alcohol gels occur, such as in splashes and drips during the hand cleaning process. In this circumstance the use of such gels could provide a false sense of security, as in reality they might increase the microbiological problem rather than reduce it. It should be noted however, some scientists suggest that alcohol in spilled gels rapidly evaporates and thus cannot stimulate growth.
Notwithstanding the controversy with A. baumanni, it is well known that some pathogenic bacteria are not killed by alcohol gels e.g. Clostridium difficile, and so it is probably better to employ conventional soap and water methods as the most reliable handwashing routine.
Future Strategies to Combat Acinetobacter Infections
- Following years of pharmaceutical industry neglect there must be an accelerated development of new antibiotics
- New antibiotics should attack multiple targets on the pathogen to avoid development of resistance
- Strict enforcement of comprehensive and deep cleansing in hospitals and other clinical establishments to prevent infections and the development of resistance
- Rigid adherence to appropriate hand hygiene practices, focusing around but not exclusive to soap and water methods to prevent cross-contamination
- Pre-prescription identification of the causative organism to prevent usage of inappropriate antibiotics that itself can promote resistance
- Halting the prescription of antibiotics generally when they are not microbiologically indicated, e.g. for viral infections
 |
