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MICROBIOLOGY LEGEND CYCLE 41 ORGANISM 3
Proteus Vulgaris
Proteus Vulgaris is a rod shaped Gram-Negative chemoheterotrophic bacterium. The size of the individual cells varies from 0.4 to 0.6 micrometers by 1.2 to 2.5 micrometers. P. vulgaris possesses peritrichous flagella, making it actively motile. It inhabits the soil, polluted water, raw meat, gastrointestinal tracts of animals and dust. In humans, Proteus species most frequently cause urinary tract infections, but can also produce severe abscesses and is widely associated with nosocomial infections.
Isolation of Organism With basic microbiological technique, samples believed to contain P. vulgaris are first incubated on 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 culture medium, MacConkey agar. Bile salts in the medium, as a normal part of the intestinal flora, suppress organisms that are not normally part of the home environment of Proteus vulgaris. MacConkey agar contains lactose, which Proteus organisms do not ferment, allowing differentiation of organisms with different fermentation. Proteus being an anaerobe can be further differentiated by incubating the culture under anaerobic conditions.
Genome Structure Rts 1 is a large conjugative plasmid isolated from Proteus vulgaris. The nucleotide sequencing of Rts 1 was completed at Shinshu University School of Medicine, Japan. The genome has 217 182 base pairs and contains 300 open reading frames. The products of 141 of these showed significant sequence similarity to known proteins and among these, 99 were homologous to proteins whose functions are known or predicted. There is also a presence of tus-like genes that could be involved in replication termination.
Cell Structure and metabolism P. vulgaris have an extra cytoplasmic outer membrane. The outer membrane contains a lipid bilayer, lipoproteins, polysaccharides and lipopolysaccharides. No spores or capsules are formed. They obtain their energy and electrons from organic molecules. It ferments glucose, sucrose, galactose, glycerol and occasionally maltose with gas production but never lactose. It liquefies gelatin, casein, and blood serum, curdling milk with acid production.
It is not limited to any specific temperature range, but good growth occurs at 20 and 30 degrees Celsius, while growth is poor at 37 degrees Celsius. P. vulgaris have two interesting features. The cells are highly motile and swarm across the surface of the agar plates, forming a very thin film of bacteria. 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 can produce urease and degrade urea to ammonia. By alkalinizing the urine, P. vulgaris makes the environment more suitable for its survival.
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24 hour culture of P. vulgaris Gram Negative rods of P. vulgaris
Ecology P. vulgaris is said to be present in all sewage, a constant source of contamination, which is a favorable medium for growth. These organisms are more prone to cause nosocomial infections. 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 a higher chance of getting exposed to a susceptible patient or hospital personnel. The result showed that P. vulgaris survived for 1-2 days. To reduce the risk of transmission of nosocomial pathogens from inanimate surfaces to susceptible patients, disinfection of surfaces in specific patient care areas is recommended.
Pathology P. vulgaris is a common species of Proteus associated with human infection. One of the virulence factors identified is that they contain fimbriae. Specific chemicals on the tip of the pili enable the organism to attach to a selected site. Due to the presence of the peritrichouse flagella, this organism is very motile. The most common infections caused by P. vulgaris are Urinary tract infections and wound infections. P. vulgaris is abundant in urease production. Urease splits urea into Carbon dioxide and ammonia. Ammonia will cause the urine to become very alkaline and may cause the formation of renal stones. Some of the symptoms of P. vulgaris infections include flank pain, hematuria and persistent alkaline urine.
Antibiotic Therapy P. vulgaris species are highly resistant to antibiotics, so infections can be difficult to cure. Their plasmids are responsible for spreading antibiotics resistance genes in a microbial population. Many Proteus species have varied multi drug resistant markers that are encoded on transferable plasmids. These resistant plasmids can be transferred from donor cells. Therefore the antibiotics-resistant plasmid markers can be easily transferred by coagulation. However most of the plasmid markers are not transferable, reflecting the characteristics of antibiotic resistance. P. vulgaris is least resistant to ciprofloxacin and cefotaxime but when it is introduced to these drugs, higher doses than normal should be used. They are also sensitive to netilmicin, meropenem, piperacillin, ampicillin and sulbactam.
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48 Monte Carlo Crescent Kyalami Business Park Kyalami, Johannesburg, 1684, RSA Tel: +27 (0)11 463 3260 Fax: + 27 (0)86 557 2232 Email: [email protected] www.thistle.co.za
References 1. http://en.citizendium.org/wiki?title=Proteus_vulguris&oldid=100832147
Questions 1. Name the two agars used to isolate Proteus vulgaris. 2. What is the temperature range that is best for growth for Proteus vulgaris? 3. What are the two interesting features that Proteus vulgaris has? 4. Which antibiotics are Proteus vulgaris least resistant to?
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