Biofilm Formation Hampers Removal of Dangerous Bacteria from Hospital Surfaces

MedicalResearch.com Interview with:
Christine Greene, Ph.D. and Chuanwu Xi, Ph.D.
School of Public Health, Department of Environmental Health Sciences
University of Michigan

Medical Research: What is the background for this study?

Response: Healthcare-associated infections (HAIs) are a serious problem globally.  Acinetobacter baumannii, a gram-negative opportunistic pathogen, was mostly unheard of 10-15 years ago, but is now a clinically significant pathogen in hospitals.  A. baumannii causes a variety of infections ranging from urinary tract infections to bacteremia and patients who are at high risk of A. baumannii infection are those who are critically ill, who have indwelling catheters or patients with long hospital says.  Once infected, the risk of mortality is high – up to 26% for in-hospital patients and as much as 43% for those in the ICU.  The mortality rate is high largely due to the rapid ability for this pathogen to develop antibiotic resistance.  Despite patient isolation, we still see hospital outbreaks because A. baumannii survives very well in the environment and it is resistant to most biocides, detergents, dehydration, and UV radiation.  A. baumannii is also a known biofilm former.  Biofilms serve to protect the microorganism.  In the open environment, biofilms protect from desiccation and other harsh environmental insults such as biocides, thereby promoting persistence in the open environment.  In the human body, biofilms protect against the immune system, provide an additional layer of protection from antibiotics and contribute to reoccurring infections in the patient.

This research characterizes the fitness (desiccation tolerance) trade-offs imposed on A. baumannii isolated from clinical and environmental settings.  This investigation compares isolates of A. baumannii from both environments on the basis of multidrug resistance, biofilms and desiccation tolerance.  We looked to see if either MDR or biofilm formation increased fitness (ability to tolerate desiccation) or impose a fitness cost depending on environmental conditions.

Medical Research: What are the main findings?

Response: We provide evidence of variation in desiccation tolerance between clinical and environmental isolates of similar phenotypes and show a trend of increased desiccation tolerance for high biofilm forming clinical isolates with additional tolerance when the ability to form biofilms is coupled with the multidrug resistance.  By contrast, biofilm formation had a significant impact on desiccation tolerance for environmental isolates.

Medical Research: What should clinicians and patients take away from your report?

Response: The sporadic rep-types of A. baumannii evaluated in this study were mostly non-ICU associated, were more likely to be susceptible to antibiotics and tolerated desiccation better than the multidrug resistant, ICU associated dominant rep-types.  These sporadic rep-type had a 43% decreased risk of cell-death compared to the dominant rep-type with strong biofilm forming capability among the environmental strains.  This means that they have ample potential to become problematic for non-ICU patients.  Patients who are quite ill are often admitted to non-ICU areas and exposed to antibiotics prior to ICU admittance.  As these patients are moved between hospital areas (to undergo various procedures such as surgery or use of burn unit baths), there is an increased risk in the transmission of the sporadic strains to patients.  Therefore, these sporadic types should not be overlooked in terms of clinical relevance.

Medical Research: What recommendations do you have for future research as a result of this study?

Response: Genetic studies are needed to identify if the variation in desiccation tolerance observed between clinical and environmental isolates resulted from different expressions of the same set of genes. In addition, since biofilm formation increases desiccation tolerance for both clinical and environmental isolates, it is critical to develop novel infection control approaches to reduce hospital acquired infections.

Citation:

The influence of biofilm formation and multidrug resistance on environmental survival of clinical and environmental isolates of Acinetobacter baumannii

Greene, Christine et al.

American Journal of Infection Control , Volume 0 , Issue 0 , Published online Feb 2 2016
DOI: http://dx.doi.org/10.1016/j.ajic.2015.12.012

Christine Greene, Ph.D. and Chuanwu Xi, Ph.D. (2016). Biofilm Formation Hampers Removal of Dangerous Bacteria from Hospital Surfaces MedicalResearch.com

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