Proteus mirabilis
Colonies of Proteus mirabilis on an agar plate
Proteus mirabilis is the name of a gram-negative bacterial species, whose representatives are rod-shaped and belong to the family Enterobacteriaceae in the genus Proteus.
Microbiological properties
The bacteria can be easily cultivated on standard culture media. They make it on gel media often circumscribed colonies like most other bacteria, but can be flat on the medium spread ( " swarm phenomenon" ) (see Figure 2). As was already noted in 1946, the possibility to single colonies ( swarms ) form a clearly visible demarcation from other colonies, which is still used for the classification of these microorganisms and, among other (toxic acting for the other colony ) to different proteins of the family of Proticine is. Proteus mirabilis is a gram -negative, facultatively anaerobic, non-spore forming, strong peritrichous flagellated - and vividly moving - rod-shaped bacteria. Form the enzyme urease, which is capable of cleaving urea. Ammonia, which thus provided the pH of the medium, for example of urine, and increased the bacteria better growth conditions occurs (a low pH is poorly tolerated by most bacteria ). Another important enzyme is phenylalanine deaminase. They lack the ability to metabolize lactose. The lack of indole production of almost all strains allows a simple definition of the second most common species of the genus, Proteus vulgaris ( indole test positive). P. mirabilis is usually a harmless saprophyte ( Destruent organic substances).
The bacteria are very different in length, this led to the designation after the ancient Greek sea god Proteus, who distinguished himself by great versatility.
The genome of Proteus mirabilis is currently decoded by the Sanger Institute (Cambridge, UK).
Importance as pathogens
In Proteus mirabilis is a facultative pathogenic ( opportunistic ) pathogens commonly found in healthy people in the colon and not necessarily cause disease. According to immunocompromised individuals may suffer from following, caused by this bacterium diseases: urinary tract infection, wound infection, pneumonia and sepsis.
In chronic urinary tract infection by Proteus mirabilis can be promoted by increasing the urinary pH, the formation of urinary stones.
Spread
Typically, there is not a transmission of infection from person to person. Source of infection is the body's bacterial community of the intestine.
Frequency
Proteus mirabilis is a rare pathogen. Urinary tract infections are caused in about 5-10 % of cases by this bacterium. In pneumonia and sepsis, the share moved by 2%. These figures are for community-acquired infections, nosocomial infections, the rate tends to be slightly higher.
Diagnostics
The diagnosis is made by culturing the pathogen from blood and urine cultures, bronchial or bronchoalveolar lavage. After applying a pure culture of the species can most easily be determined by biochemical methods (" Bunte Reihe ").
Therapy
The treatment of infection by Proteus mirabilis should, whenever possible, be carried out by resistance testing ( antibiogram ). The initial " calculated " therapy can be done eg with co-trimoxazole, a third-generation cephalosporin or a fluoroquinolone. Natural resistance exist to tetracyclines, tigecycline, colistin, and nitrofurantoin.
The problem for the therapy is in particular the ability of the bacterium to produce extended-spectrum - β -lactamases (ESBL ). In order for the bacteria antibiotics from β -lactam type can make ineffective (eg penicillins, cephalosporins).