Comamonas testosteroni

Comamonas testosteroni is a Gram-negative, rod-shaped, aerobic bacterium belonging to the family Comamonadaceae. It is commonly found in environmental sources such as soil, water, sewage, wastewater, and industrial effluents—particularly where organic material is abundant. Initially classified under the Pseudomonas genus, it was later reclassified as Comamonas based on molecular and phylogenetic studies (Stanier et al., 1966).

Comamonas testosteroni
Scientific classification
Domain:	Bacteria
Kingdom:	Pseudomonadati
Phylum:	Pseudomonadota
Class:	Betaproteobacteria
Order:	Burkholderiales
Family:	Comamonadaceae
Genus:	Comamonas
Species:	C. testosteroni
Binomial name
Comamonas testosteroni (Marcus and Talalay 1956) Tamaoka et al. 1987
Synonyms
Pseudomonas testosteroni Marcus and Talalay 1956 Pseudomonas dacunhae Arima Pseudomonas cruciviae Tamaoka, Ha, and Komagata, 1987

This bacterium is notable for its exceptional metabolic flexibility. It can utilize testosterone as a carbon source and is capable of degrading other complex sterols, including ergosterol and estrogens. Its ability to break down a wide range of organic pollutants makes it a valuable organism for bioremediation and various industrial applications. For example, the strain C. testosteroni I2gfp has been used in bioaugmentation trials aimed at treating toxic industrial byproducts such as 3-chloroaniline.

Although C. testosteroni is not typically part of the human microbiome, it was first identified as a human pathogen in 1987, according to the National Library of Medicine. Since then, it has been associated with rare but documented cases of human infections, primarily involving the bloodstream.

Overall, Comamonas testosteroni plays a key ecological role in organic compound degradation and continues to be a species of interest in environmental and medical microbiology.

Metabolic Capabilities and Biodegradation

One of the most studied aspects of C. testosteroni is its metabolic diversity. It has the ability to break down various organic pollutants, including:

• Steroids (such as testosterone, which inspired its name)
• Aromatic compounds (e.g., phenol, biphenyl)
• Plastics and synthetic chemicals (potential application in plastic degradation)

Due to these capabilities, C. testosteroni has been explored for bioremediation, particularly in wastewater treatment and industrial pollution control.

Moreover, beyond its role as a rare human pathogen, C. testosteroni has significant environmental applications. Strains like ZG2 have shown promise in remediating nickel and cadmium-contaminated soils, facilitating the safe production of vegetables in affected areas.  Additionally, certain strains of C. testosteroni can utilize pollutants, including androgens and estrogens, as carbon sources, highlighting their potential in bioremediation efforts aimed at reducing environmental contamination.

In summary, while Comamonas testosteroni is predominantly an environmental bacterium with low pathogenic potential, it can, in rare cases, cause human infections, especially in healthcare settings. Its unique ability to degrade complex organic materials also holds promise for environmental applications.

Medical Treatment

While these infections are uncommon, they can be serious. Effective treatment typically involves:

1. Accurate Diagnosis:

Identifying C. testosteroni as the cause of infection is essential. This often requires specialized laboratory tests, as standard cultures may not detect this rare pathogen.

2. Appropriate Antibiotic Therapy:

Once identified, treatment usually includes antibiotics such as aminoglycosides, fluoroquinolones, carbapenems, piperacillin-tazobactam, trimethoprim-sulfamethoxazole, or cephalosporins. However, antibiotic resistance can occur, so it’s important to tailor therapy based on the specific susceptibility profile of the isolated strain.

3. Supportive Care:

In severe cases, additional supportive measures may be necessary. For instance, a case involving peritonitis due to C. testosteroni in a pediatric patient responded well to intraperitoneal ciprofloxacin, leading to improvement without the need for catheter removal.

4. Infection Control:

Given its environmental presence, strict infection control practices are crucial in healthcare settings to prevent the spread of C. testosteroni. This includes proper sterilization of medical equipment and adherence to hygiene protocols.

It’s important to note that while C. testosteroni infections can be serious, they are rare, and with prompt and appropriate treatment, patients often recover without significant complications.

Biodegradation

C. testosteroni is studied for the ability of strains in this species to degrade diverse aromatic carbon compounds, including many xenobiotic waste pollutants, such as 4-chloronitrobenzene and 4-hydroxybenzoate.^[1] A number of strains of Comamonas, including C. testosteroni, have been shown to consume terephthalic acid, one of the components of PET plastic, as a sole carbon source.^[2] C. testosteroni was found to catabolize terephthalate, vanillate, and 4-hydroxybenzoate to a protocatechuate intermediate, which is then degraded by initiation of ring formation at the 4,5-meta position.^[3] Because of its ability to degrade aromatic pollutants with relevance to bioremediation, methods for genetic engineering in Comamonas have begun to be developed.^[4]

Virulence

Though these organisms have low virulence, they can occasionally cause human diseases. They can be found in intravenous catheters, the respiratory tract, abdomen, urinary tract, and the central nervous system. Symptoms of infection may variously include vomiting, watery diarrhea, and meningitis.^[5]