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Infections with the unusual human pathogens Agrobacterium species and Ochrobactrum anthropi
D Alnor1, N Frimodt-Møller, F Espersen
1Department of Clinical Microbiology, Bispebjerg Hospital, Copenhagen, Denmark.
Abstract:
Agrobacterium species and Ochrobactrum anthropi are generally considered innocuous in clinical settings, yet during the last decade a number of sporadic cases of human infection due to these organisms have been reported. We studied nine cases of infection (septicemia and peritonitis) caused by Agrobacterium-like microorganisms in eight patients. All patients were immunocompromised and had permanent central venous or peritoneal dialysis catheters in place. Seven patients were women, and eight infections were community acquired. Six isolates were identified as Agrobacterium species and three as O. anthropi. These two groups of strains differed in the production of beta-galactosidase and of acid from lactose, erythritol, salicin, and cellobiose. All strains were strictly aerobic, peritrichous, gram-negative bacilli that produced oxidase, urease, and acid from glucose, fructose, arabinose, xylose, mannitol, inositol, and ethanol. The in vitro adherence of isotope-labeled bacteria to silicone tubes was similar to that of staphylococci. We conclude that Agrobacterium species and O. anthropi can be pathogenic in immunocompromised patients with permanent catheters.
Insights
Agrobacterium and Ochrobactrum anthropi, typically harmless bacteria, can cause serious infections like septicemia in immunocompromised patients with catheters. These opportunistic pathogens highlight the need for vigilance in clinical settings.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Medical Bacteriology
Background:
- Agrobacterium species and Ochrobactrum anthropi are generally considered non-pathogenic in clinical environments.
- Recent years have seen a rise in sporadic human infections caused by these organisms.
Purpose of the Study:
- To investigate nine cases of infection (septicemia and peritonitis) caused by Agrobacterium-like microorganisms in eight patients.
- To characterize the clinical and microbiological features of these infections.
Main Methods:
- Case series study of nine infections in eight immunocompromised patients with indwelling catheters.
- Biochemical characterization of bacterial isolates, including Agrobacterium species and O. anthropi.
- In vitro assessment of bacterial adherence to silicone tubing.
Main Results:
- All patients were immunocompromised and had permanent central venous or peritoneal dialysis catheters.
- Seven infections occurred in women, and eight were community-acquired.
- Biochemical tests differentiated Agrobacterium and O. anthropi strains, while all shared key characteristics like aerobic respiration and urease production.
Conclusions:
- Agrobacterium species and O. anthropi can act as opportunistic pathogens in immunocompromised individuals, particularly those with indwelling catheters.
- The findings underscore the potential pathogenicity of these bacteria in specific clinical scenarios.
- Further research into the virulence factors and transmission of these organisms is warranted.