Proteus mirabilis
| Proteus mirabilis | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Colonies of Proteus mirabilis on an agar plate |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Proteus mirabilis | ||||||||||||
| Hauser , 1885 |
Proteus mirabilis is the name of a gram-negative bacterial species whose representatives are rod-shaped and belong to the genus Proteus in the Morganellaceae family.
Microbiological properties
Proteus mirabilis are gram-negative , facultative anaerobic , non-spore-forming, strongly peritrich flagellated - and thus vigorously moving - rod-shaped bacteria. P. mirabilis is usually a harmless saprophyte (destroyer of organic substances).
The bacteria produce the enzyme urease , which can break down urea . This creates ammonia , which increases the pH value of the medium, for example of urine, and thus provides the bacterium with better growth conditions (a low pH value is poorly tolerated by most bacteria). Other important enzymes they have at their disposal are phenylalanine deaminase and ornithine decarboxylase (ODC). In contrast, the enzymes lysine decarboxylase (LDC) and arginine dihydrolase (ADH) are missing . They can form hydrogen sulfide from sulfur-containing amino acids and are able to hydrolyze gelatin . They lack the ability to metabolize lactose . The lack of indole production of almost all strains allows a simple differentiation from the second most common species of the genus, Proteus vulgaris ( indole test positive).
Proteus bacteria can easily be cultivated on common culture media . They often do not form circumscribed colonies on gel media like most other bacteria, but can spread over the nutrient medium (“ swarm phenomenon ”, see figure on the right). As was already noted in 1946, individual colonies (swarms) can form a clearly visible demarcation from other colonies, which is still used today to classify these microorganisms and, among other things, various proteins from the family of the (which are toxic to the other colony) Proticine lies.
The bacteria are very different in length, this led to the naming after the ancient Greek god of the sea, Proteus , who was characterized by great versatility.
The genome of Proteus mirabilis is currently being deciphered by the Sanger Institute (Cambridge, UK).
Significance as a pathogen
In Proteus mirabilis is an optionally pathogenic (opportunistic) pathogens, which often also in healthy individuals in the colon is common and not necessarily caused diseases. Correspondingly immunocompromised people can suffer from the following symptoms caused by this bacterium: urinary tract infection , wound infection , pneumonia and sepsis .
In the case of chronic urinary tract infections caused by Proteus mirabilis , the increase in the urine pH can promote the development of urinary stones .
Spread
Typically, the pathogen is not transmitted from person to person. The source of infection is the body's own bacterial community in the intestine .
frequency
Proteus mirabilis is a rare pathogen. Urinary tract infections are caused by this bacterium in around 5–10% of cases. In pneumonia and sepsis , the proportion is around 2%. These figures apply to community-acquired infections; the rate tends to be somewhat higher for nosocomial infections. Rarely occurring indole- positive strains of the bacterium Proteus mirabilis have developed a multi-resistance .
Diagnosis
The diagnosis is made by cultivating the pathogen from blood and urine cultures, bronchial secretions or bronchoalveolar lavage. After creating a pure culture, the species can most easily be determined using biochemical methods (“ Bunte series ”).
therapy
Treatment of an infection with Proteus mirabilis should, whenever possible, be carried out after a resistance test ( antibiogram ). The initial “calculated” therapy can e.g. B. with cotrimoxazole , a cephalosporin of the 2nd / 3rd. Generation or with a fluoroquinolone . Natural resistances exist to tetracyclines , tigecycline , colistin and nitrofurantoin .
Bacterial strains that produce extended-spectrum-β-lactamases ( ESBL ) are problematic for therapy . Such bacterial strains are resistant to antibiotics of the β-lactam type (e.g. penicillins , cephalosporins of all generations).
Historical
Proteus mirabilis was discovered and first described by the Erlangen pathologist Gustav Hauser in 1885 . The article is called On Putrid Bacteria and Their Relationship to Septicemia. A contribution to the morphology of the split fungi. The epithet P. mirabilis means "wonderful, amazing".
The OX antigens from Proteus, especially OX-19, are agglutinins of the Weil-Felix reaction, the classic detection method for spotted fever caused by rickettsiae , as they show cross-reactivity with human antibodies against rickettsiae and thus agglutination when added to the blood ( Cause "precipitation"). However, the test has a low specificity and sensitivity . During the Second World War in occupied Poland, the two doctors Stanisław Matulewicz and Eugeniusz Łazowski succeeded in simulating a typhus epidemic for years by injecting Proteus suspensions and thus saving an estimated 8,000 people.
Individual evidence
- ^ A b C. M. O'Hara, FW Brenner, JM Miller: Classification, identification, and clinical significance of Proteus, Providencia, and Morganella . In: Clinical Microbiology Reviews . tape 13 , no. 4 . American Society for Microbiology, October 2000, ISSN 0893-8512 , p. 534-546 , doi : 10.1128 / cmr.13.4.534-546.2000 , PMID 11023955 , PMC 88947 (free full text).
- ↑ Spectrum of Science. January 2009, pp. 16-17: Bacterial club dairy.
- ↑ Recommendation of the Commission for Hospital Hygiene and Infection Prevention (KRINKO) at the Robert Koch Institute (RKI): Hygiene measures in the event of infections or colonization with multi-resistant Gram-negative rods. In: Federal Health Gazette. 2012, No. 55, October 2012, pp. 1311–1354, doi: 10.1007 / s00103-012-1549-5 ( full text as PDF file ), especially: p. 1318 → 2.1.4 Other enterobacteria.
- ↑ "Current active ingredient: Rational antibiotic therapy for urinary tract infections", Edition 2/2012 ( Memento from November 7, 2014 in the Internet Archive )
- ^ R. Leclercq et al .: EUCAST expert rules in antimicrobial susceptibility testing . In: Clinical Microbiology and Infection . tape 19 , no. 2 . Wiley-Blackwell, 2013, ISSN 1469-0691 , pp. 141-160 , doi : 10.1111 / j.1469-0691.2011.03703.x , PMID 22117544 ( wiley.com [accessed February 17, 2013]).
- ^ Jean Euzéby, Aidan C. Parte: Genus Proteus. In: List of Prokaryotic names with Standing in Nomenclature, Systematics of Bacteria (LPSN) . Retrieved December 23, 2019 .
- ↑ John DC Bennett, Lydia Tyszczuk: Deception by immunization, revisited British Medical Journal 1990, Volume 301, Issue 22-29 . December 1990, pages 1471-1472