Proteus vulgaris
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| Proteus vulgaris | ||||||||||||||
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| Proteus vulgaris |
Description and significance
P. vulgaris is rod-shaped Gram-negative chemoheterotroph. The size of individual cells varies from 0.4~0.6μm by 1.2~2.5μm. P. vulgaris possesses peritrichous flagella and it is actively motile. It inhabits in gastrointestinal tracts of animal, soil, polluted water, raw meat, and dust. P.vulgaris is considered to be pathogenic bacteria. In human, it can cause urinary tract infections, wound infections, and is a common cause of sinus and respiratory infections.
Proteus can be isolated from a sample of soil. Organism is inoculated in a nutrient agar to form colonies. To test the Gram-negative and oxidase-negative characteristics of Enterobacteriaceae, Gram stains and oxidase tests are performed. The colonies of interest are then inoculated onto a selective and differential medium-McConkey agar. McConkey agar is suitable for Proteus for two reasons. First reason is that the bile salt constituent allows the growth of Proteus, which is a part of the intestinal flora, while selectively inhibits organisms that are not suitable to grow in intestinal environments. Second reason is that McConkey agar can differentiate the non lactose-fermenting characteristic of Proteus from the lactose-fermenting organisms. Since Proteus is an anaerobic organism, the plate agar can be incubated in an anaerobic jar.[1]
Genome structure
The nucleotide sequencing of Rts1 was completed at Shinshu University School of Medicine, Department of Bacteriology, Japan. Rts1 is a large conjugative plasmid isloated from Proteus vulgaris. The genome is 217,182 bp in length and contains 300 open reading frames(ORFs). The products of 141 ORFs out of 300 ORFs showed significant sequence similarity to known proteins and among these, 99 ORFs were homologous to proteins whose functions are known or predicted. The interesting finding in this study was the presence of tus-like genes that could be involved in replication termination. [2]
Proteus species are highly resistant to antibiotics, therefore infections caused by Proteus species are difficult to cure. Their plasmids are responsible for spreading antibiotics resistance genes in a microbial population. A large number of Proteus species has varied multi-drug resistant markers that are encoded on transferable plasmids. The resistant plasmids can be transferred with the frequency ranging from 2x10-4 to 4x10-2 per donor cells. Therefore, the antibiotics resistant plasmids markers can be easily transferred by conjugation. However, most of the plasmid markers are not transferable, reflecting the characteristic of antibiotic resistance. Proteus vulgaris is known to be least resistant to ciprofloxacin and cefotaxime but when it is introduced to these drugs, higher doses than "normal" should be used. For example, at lease 2000mg of ciprofloxacin should be taken per day instead of "standard" 1000mg per day.
Cell structure and metabolism
Proteus species possess an extracytoplasmic outer membrane. The outer membrane contains a lipid bilayer, lipoproteins, polysaccharides, and lipopolysaccharides. No spores or capsules are formed.
P. vulgaris obtains energy and electrons from organic molecules. It ferments glucose, sucrose, galactose, glycerol and occasionally maltose with gas production, but never lactose; liquefy gelatin, casein, and blood serum, curdling milk with acid production. It is not limited to any specific temperature range, although it was reported that good growth occurs at 20° and 30°, while the growth is poor at 37°.
P. vulgaris has two interesting features. One is that the cells are highly motile and swarm across the surface of the agar plates. The cells form very thin film of bacteria on the surface by swarming. When the cells stop and undergo a cycle of growth and division, the swarming periods are interspersed with periods and the colony has a distinct zonation. The other feature is that P. vulgaris has ability to produce urease and degrade urea to ammonia. By alkalinizing the urine, P. vulgaris makes the environment more suitable for its survival.
Ecology
P. vulgaris is said to be present in all sewage, a constant source of contamination, which is a favorable medium for growth.
Pathology
P. vulgaris and P. mirabilis are two common species of genus Proteus associated with human infection. One of the virulence factors identified is that they contain fimbriae. The specific chemicals on the tip of pili enable organism to attach to selected site. Due to presence of peritrichouse flagella, Proteus has extremely high motility. If it were the size of human, it could travel at the speed of 100 mph. The most common infections caused by this genus are urinary tract infection(UTI) and wound infection. P. mirabilis is a major agent in UTI. Proteus is abundant in urease production. Urease splits urea into carbon dioxide (CO2) and ammonia (NH3). Ammonia causes the urine to become extremely alkaline (pH >7), and may cause the formation of renal stones. Some of the symptoms of Proteus infection may be UTI, flank pain, hematuria, persistent urine pH >7.
In animals, some strains of Proteus can be harmful while some do not affect the organism. The Proteus isolated from the vomited material from patients with meat-poison caused diarrhea and death when fed to mice. When different cultured Proteus was fed to mice, neither sickness nor immunity was present. When P. vulgaris was injected into the peritoneal cavity of guinea pig, it caused a rapid death. However, when the same amount was injected into the subcutis, an extensive necrosisresulted. Intravenous injection in cats caused severe vomiting, bloody diarrhea, and death.
Current Research
"Antibacterial and antifungal activities of different parts of Tribulus terrestris L. growing in Iraq"
- Antimicrobial activity of organic and aqueous extracts from fruits, leaves and roots of Tribulus terrestris was examined against 11 species of organisms including Proteus vulgaris.Tribulus terrestris is an Iraqi medicinal plant that is used as urinary anti-infective in folk medicine. Different parts of Turkish and Iranian T. terrestris are already known to have antibacterial activity but the antimicrobial activity of Iraqi T. terrestris has not been studied until this experiment.
- Different extracts from fruits, leaves and roots of Iraqi T. terrestris were tested at concentrations of 0.01~5.00 mg/ml, and evaluated in MIC values. Ethanol extract of T. terrestris fruit was most active against both gram-positive and gram-negative including P. vulgaris with the MIC value of 0.15 mg/ml. The result of aqueous extract from T. terrestris leaves showed that it was active against P. vulgaris with MIC value of 2.50 mg/ml. Extracts from T. terrestris roots showed no activity or very little activity against targeted bacteria.
- In conclusion, all of the extracts from T. terrestris growing in Iraq have ability to inhibit the growth of most of the tested organisms. The gram-positive bacteria were most sensitive to the ethanol extract of T. terrestris fruits, while P. vulgaris was the most resistant among the tested gram-negative bacteria.
"Action of Lysozyme on Penicillin-Induced Filaments of Proteus vulgaris"
- Low-dose of penicillin causes gram-negative bacteria to transform into filaments, but penicillin itself does no harm to cell envelopes and cell wall. The study done by Jacqueline Fleck, Jean-Pierre Martin, and Michèle Mock demonstrates that the hen egg white lysozyme, which does not affect normal cells of P. vulgaris P 18, modifies the envelope of filaments.
- In conclusion, low-dose of penicillin stopped cell septation in P. vulgaris P 18 and caused its transformation into filaments without changing the structure of cell envelope. In the penicillin-induced filaments, lysozyme penetrated the cell envelope and dissolved the inner most layer of the cell wall. The action of penicillin caused removal of the barrier to this enzyme. As a result, the five-layered wall is reduced to three-layered structure. This three-layered structure contained the outer membrane and the filament was transformed into spheroplasts.
"How long do nosocomial pathogens persist on inanimate surfaces? A systematic review"
- To prevent transmission of nosocomial pathogens within hospitals, the persistence of nosocomial pathogens on surfaces was assessed. The longer a nosocomial pathogen remains on a surface, the longer it may be a source of transmission and thus there is higher chance of getting exposed to a susceptible patient or hospital personnel. The data on the different nosocomial pathogens on inanimate surface was collected by Axel Kramer,Ingeborg Schwebke,and Günter Kampf.
- The result showed that Proteus vulgaris survived 1-2 days. Other gram-negative can survive on inanimate surfaces for months, while some viruses can survive from few hours to days
- In conclusion, in order to reduce the risk of transmission of nosocomial pathogens from inanimate surfaces to susceptible patients, a disinfection of surfaces in specific patient-care areas is recommended.