Proteus mirabilis

Proteus spp. were first described in 1885 by Gustav Hauser, who noted their characteristic of intense swarm growth.

Proteus mirabilis, a gram-negative bacterium of the genus Proteus, is a facultatively pathogenic (opportunistic) pathogen that is also frequently found in the colon of healthy individuals and does not necessarily cause disease. Typically, there is no person-to-person transmission of the pathogen. The source of infection is the body's own bacterial community in the intestine.

Proteus mirabilis is responsible for a wide range of infections such as catheter-associated urinary tract infections (about 5-10% of cases), wound infections (especially in people with diabetes), gastroenteritis, and in some cases bacteremia, less commonly pneumonia and sepsis (about 2% of cases) (Gomaa S et al. 2019). In chronic urinary tract infections caused by Proteus mirabilis, the increase in urine pH may promote the formation of urinary stones

Diagnosis is made by culturing the pathogen from blood and urine cultures, bronchial secretions or bronchoalveolar lavage. Phenotypic features of this bacterium include swarming motility (see Fig.), urease and hemolysin production, and synthesis of numerous adherens fimbriae (Mobley HLT 2019). Species is most easily determined by biochemical methods ("colorful series"). Furthermore, MALDI-TOF mass spectrometry can be used for assignment.

Treatment of an infection caused by Proteus mirabilis should, whenever possible, be carried out after resistance testing (antibiogram). The initial "calculated" therapy may be e.g. with cotrimoxazole, with a 2nd/3rd generation cephalosporin or with a fluoroquinolone. Natural resistance exists to tetracyclines, tigecycline, colistin and nitrofurantoin.

Bacterial strains that produce extended-spectrum-β-lactamases(ESBL) are an increasing therapeutic problem (Yazdi M et aal. 2018). Such bacterial strains are resistant to β-lactam-type antibiotics (e.g. penicillins, cephalosporins of all generations). The extent to which the use of bacteriophages (e.g. phages from the Siphoviridae family) are options for the treatment of biofilm-based multidrug-resistant (MDR) Proteus mirabilis infections remains to be seen (Gomaa S et al. 2019).

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2. Gomaa S et al. (2019) Elimination of multidrug-resistant Proteus mirabilis biofilms using bacteriophages. Arch Virol 164:2265-2275.
3. Hamilton AL et al (2018) Proteus spp. as putative gastrointestinal pathogens. Clin Microbiol Rev. 31:e00085-17.
4. Mobley HLT (2019) Proteus mirabilis Overview. Methods Mol Biol 2021:1-4.
5. Wright EK et al (2017) Microbial factors associated with postoperative Crohn's disease recurrence. J Crohns Colitis 11:191-203
6. Yazdi M et aal. (2018) Isolation and Characterization of a Lytic Bacteriophage (vB_PmiS-TH) and Its Application in Combination with Ampicillin against Planktonic and Biofilm Forms of Proteus mirabilis Isolated from Urinary Tract Infection. J Mol Microbiol Biotechnol 28:37-46.