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Patients in the intensive care unit are exposed to amoeba-associated pathogens
Bernard La Scola1, Liazyd Mezi, Jean-Pierre Auffray
1Unité des Rickettsies, Hôpital de Ste Marguerite, Marseille, France.
Objective:
To study the role of amoeba-associated alpha Proteobacteria as infecting agents in intensive care units (ICUs).
Design:
Amoeba-associated alpha Proteobacteria were isolated from water samples taken from ICU taps and general hospital reservoir tanks using an amoebal co-culture procedure. Isolates were identified by 16S rDNA gene sequence comparison, and one isolate of each species was used as an antigen in a microimmunofluorescence assay to test the sera of the patients in the ICUs and compare them with those of control subjects.
Setting:
The four university hospitals in Marseilles, France.
Patients:
The sera of 85 patients in the ICUs with nosocomial pneumonia were tested.
Results:
We isolated 64 bacterial strains that were identified as Afipia species or close relatives within the Rhizobiaceae subgroup of alpha Proteobacteria. These bacteria were assigned to 8 different species. Eleven patients were found to have an elevated antibody titer to either Afipia genospecies 1, or 3 still unnamed bacteria. No specific antibodies were detected in 100 control subjects (P < .01).
Conclusion:
These preliminary results support the hypothesis that ICU patients are exposed to amoeba-associated alpha Proteobacteria.
Insights
Intensive care unit (ICU) patients may be exposed to amoeba-associated alpha Proteobacteria, a potential infectious agent. Preliminary findings show elevated antibody titers in ICU patients, suggesting a link to these bacteria.
Area of Science:
- Microbiology
- Infectious Diseases
- Environmental Health
Background:
- Intensive care units (ICUs) present unique challenges for infection control.
- Amoeba-associated bacteria are emerging as potential opportunistic pathogens.
Purpose of the Study:
- To investigate the role of amoeba-associated alpha Proteobacteria as infectious agents in ICUs.
- To determine if ICU patients are exposed to these specific bacteria.
Main Methods:
- Isolation and identification of alpha Proteobacteria from ICU water sources using amoebal co-culture and 16S rDNA sequencing.
- Serological testing (microimmunofluorescence assay) of ICU patients and control subjects against bacterial antigens.
Main Results:
- Sixty-four bacterial strains identified as Afipia species or related alpha Proteobacteria were isolated.
- Eleven of 85 ICU patients with nosocomial pneumonia showed elevated antibody titers to specific Afipia genospecies.
- No specific antibodies were detected in 100 control subjects.
Conclusions:
- Preliminary results support the hypothesis of ICU patient exposure to amoeba-associated alpha Proteobacteria.
- Further research is warranted to elucidate the clinical significance of this exposure.