Proteus Bacteria Characteristics

Proteus

• Proteus bacteria are Gram-negative, aerobic, and highly motile, with a characteristic ammonia smell.
• They tend to swarm, spreading rapidly over the surface of solid media, making it difficult to isolate other bacteria.
• Adding chloralhydrate or potassium tellurite to the medium can inhibit the spreading of growth.
• Proteus does not ferment lactose, rapidly liquefy gelatin, produce H2S, and decompose urea.
• On MacConkey agar, colonies appear pale in color, on brilliant green agar and XLD media, red colonies appear.
• Colonies are 2-3 mm in diameter, non-hemolytic, shiny, round, and grayish in color.
• On KIA, Proteus vulgaris gives A/A + H2S, and Salmonella and P.mirabilis give K/A + H2S.
• Proteus species are free-living in water, soil, and sewage, and can cause diseases in the urogenital and gastrointestinal tracts of humans.

Pseudomonas Aeruginosa

• Pseudomonas aeruginosa is an important potential pathogen, causing infections in various animal species and humans.
• It has been reported to infect wounds, giving rise to blue-green pus, and causing mastitis in dairy cattle, pneumonia in red deer, and green wool infection in sheep.
• It is also reported in cases of cystic fibrosis in humans and urinary tract and ear infections.
• However, the organism is a frequent contaminant, and its isolation is not necessarily clinically significant.
• It is an important hospital-acquired pathogen, causing nosocomial infections.
• Pseudomonas aeruginosa grows well on selective agar media used for Enterobacteriaceae, with colony morphology similar to those of enteric bacteria.
• However, unlike Enterobacteriaceae, Pseudomonas are oxidase positive.
• On blood agar, most Pseudomonas species form large, flat, spreading gray colonies with irregular margins.
• Some cultures are mucoid, while others are beta-hemolytic, and most have a fruit-like or sweet ammonia odor.
• Pseudomonas aeruginosa is slow-growing at 4°C but grows at 42°C.
• It oxidizes glucose but not other sugars, liquefies gelatin, hydrolyzes arginine, and is H2S negative, urea positive, indole negative, oxidase and catalase positive.
• In the O-F test, it oxidizes glucose in the aerobic tube, turning the color from green to yellow.