In short
Proteus mirabilis (inactivated) is an inactivated bacterial vaccine studied for preventing urinary tract infections (UTIs). It is the active component of StroVac, a vaccine that contains inactivated germs from ten specified enterobacteria, including Proteus mirabilis. One authorised Phase 3 trial is evaluating laboratory methods to measure immune responses after StroVac vaccination in 20 participants.
Key points
- Proteus mirabilis is a Gram-negative bacterium that commonly causes urinary tract infections, especially in catheterised patients.
- The inactivated form is used in StroVac, a vaccine against recurrent urinary tract infections.
- One Phase 3 proof-of-concept trial is authorised to evaluate immunological assays after StroVac vaccination.
- The trial plans to enrol 20 participants and measure antibody responses in blood and urine.
- The study aims to detect IgG antibodies in plasma and IgA antibodies in urine against ten bacterial strains.
- Proteus mirabilis can cause serious complications including kidney damage, sepsis, and bacteraemia.
What is Proteus mirabilis (inactivated)?
Proteus mirabilis is a motile Gram-negative bacterium belonging to the Enterobacteriaceae family. It inhabits the environment and can cause infections of the skin, respiratory tract, wounds, and urinary tract. The inactivated form of this bacterium is used as a vaccine component. In the clinical trial registry, the substance appears as the active ingredient of StroVac, an injection suspension containing inactivated germs of specified enterobacteria.
Proteus mirabilis is an opportunistic pathogen that accounts for less than 0.05% of the intestinal microflora of healthy humans. It is mainly associated with urinary tract infections, particularly catheter-associated urinary tract infections in long-term catheterised patients. Infections caused by this bacterium can lead to renal stone accumulation, complete kidney damage, and in severe cases, sepsis and bacteraemia.
How does Proteus mirabilis (inactivated) work?
As an inactivated bacterial vaccine, Proteus mirabilis (inactivated) is intended to stimulate the immune system to produce antibodies against the bacterium. The clinical trial evaluates whether vaccination with StroVac induces patient-specific IgG antibodies in plasma and IgA antibodies in urine against each of the ten bacterial strains contained in the vaccine. The study also investigates methods to detect functional antibodies, including an opsonophagocytosis assay, agglutination test, and neutralisation test with human serum.
Proteus mirabilis is known for its ability to swarm across surfaces in a striking bull's-eye pattern, a form of flagella-mediated motility that contributes to its virulence. The bacterium is also characterised by resistance to polymyxin antibiotics such as polymyxin B, which is considered an antibiotic of last resort for Gram-negative infections.
Which conditions is it used or studied for?
- Urinary tract infection (UTI) — the clinical trial is authorised to evaluate immune responses after StroVac vaccination in the context of urinary tract infection.
- Catheter-associated urinary tract infection (CAUTI) — Proteus mirabilis is a frequent cause of UTIs in patients undergoing long-term catheterisation.
- Pyelonephritis — kidney infection caused by the bacterium primarily affects individuals with indwelling catheters or structural abnormalities of the urinary tract.
How is Proteus mirabilis (inactivated) given?
In the clinical trial, Proteus mirabilis (inactivated) is administered as part of StroVac, an injection suspension. The intervention is described as containing 501 mg of inactivated germs of specified enterobacteria, given by application. The registry record indicates that the vaccine is given as an injection, with the study collecting blood and urine samples to measure antibody responses after vaccination.
What do the clinical trials show?
One Phase 3 proof-of-concept trial is authorised to evaluate immunological assays using human blood and urine samples after vaccination with StroVac. The trial plans to enrol 20 participants. The primary outcomes are the increase of patient-specific IgG levels against each target bacterial strain in plasma, and the increase of patient-specific IgA levels against each target bacterial strain in urine, measured from baseline before vaccination to Visit 4 after vaccination.
The study also aims to determine whether laboratory methods including opsonophagocytosis assay (OPA), agglutination test, and neutralisation test are suitable for detecting functional antibodies against all ten bacterial strains contained in StroVac. The trial status is authorised, meaning recruitment has not yet been reported as completed.
What side effects are known?
The provided sources do not report specific side effects for Proteus mirabilis (inactivated) or StroVac. The clinical trial registry record does not include a safety outcomes section in the data provided.