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 (around 5-10% of cases), wound infections (especially in people with diabetes), gastroenteritis and, in some cases, bacteremia, less frequently pneumonia and sepsis (around 2% of cases) (Gomaa S et al. 2019). In chronic urinary tract infections caused by Proteus mirabilis, the development of urinary stones can be favored by the increase in urine pH.

Diagnosis is made by culturing the pathogen from blood and urine cultures, bronchial secretions or bronchoalveolar lavage. The phenotypic characteristics of this bacterium include swarming motility (see figure), urease and haemolysin production and the synthesis of numerous adherence fimbriae (Mobley HLT 2019). The species is most easily determined using biochemical methods ("Bunte Reihe"). Furthermore, an assignment can be made using MALDI-TOF mass spectrometry.

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

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

1. Armbruster CE et al. (2017) Pathogenesis of Proteus mirabilis infection. EcoSal Plus 8:10.1128/ecosalplus.ESP-0009-2017.
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.