Pseudomonas aeruginosa original .pptx pptx

Gram-negative, aerobic, non-spore forming rod
Pseudomonas aeruginosa is a gram-negative, aerobic, non-spore forming rod that is capable of causing a variety of infections in both immunocompetent and immunocompromised hosts.

1. Pseudomonas aeruginosa Sneha kpaul II-MSc MICROBIOLOGY Sri Ramakrishna college of arts and science for women

2. History Pseudomonas aeruginosa is a bacterium that was first isolated in 1882 by French pharmacist Carle Gessard from wound infections in soldiers whose bandages had a blue and green colour.  Gessard's study, titled "On the blue and green coloration of bandages", likely described pyocyanin, a blue/green compound with antimicrobial and toxin properties.  The name Pseudomonas comes from two Greek words, pseudo meaning "false" and monas meaning "single unit", while aeruginosa comes from the Latin word aerūgō meaning "rusted copper".

3. Morphology It is a slender gram negative bacillus, 1.5-3 μ m × 0.5 μ m , motile by a polar flagellum. Occasional strains have two or three flagella. Clinical isolates are often piliated. The flagella yield heat-labile antigens (H antigen). It is noncapulated but many strains have a mucoid slime layer. Mucoid strains particularly isolates from cystic fibrosis patients.

4. Cultural characteristics It is obligate aerobe, but can grow anaerobically if nitrate is available. Growth occurs at a wide range of temperatures, 6-42C, the optimum being 37C. It grows well on ordinary media, producing large, opaque, irregular colonies, with a distinctive, musty, or earthy smell. Iridescent patches with metallic sheen are seen in cultures on nutrient agar. It grows on MacConkey and DCA media, forming non- lactose-fermenting colonies. Many strains are hemolytic on blood agar.

5. Cont… Ps . aeruginosa produces a number of pigments, the best known being pyocyanin and fluorescin. Pyocyanin is a bluish green pigment soluble in water and chloroform. Fluorescin is a greenish yellow pigment soluble in water not in chloroform. In old cultures it may be oxidized to a yellowish brown pigment. Pyocyanin only produces Ps.aeruginosa but fluorescin may produced many other species also. Others pigments produced are pyorubin and pyomelanin . Ps aeruginosa emerging as the dominant bacterium in mixed infections.

6. Biochemical reactions The metabolism is oxidative and nonfermentive. Indole, MR, VP, and H2S tests are negative. Nitrates are reduced to nitrites and further to gaseous nitrogen. Catalase, Oxidase and Arginine dihydrolase tests are positive.

7. Epidemiology Pseudomonas species normally inhabit soil, water, and vegetation and can be isolated from the skin, throat, and stool of healthy persons. They often colonize hospital food, sinks, taps, mops, and respiratory equipment. Spread is from patient to patient via contact with fomites or by ingestion of contaminated food and water.

8. Pathogenicity pseudomonas aeruginosa infections varies from localized infections of the skin to life threatening systemic diseases. Localized wound infections Systemic infections – cystic fibrosis Nosocomial infections – device associated infections - environmental moist conditions

9. clinical significance

10. Resistance The bacillus not particularly heat resistant, being killed at 55C in one hour but exhibits a high degree of resistance to chemical agents. It is resistant to the common antiseptic quaternary ammonium compounds, chloroxylenol and hexachlorophene and may even grow profusely in bottles of such antiseptic lotions kept for use in hospitals. Indeed, selective media have been devised for Ps. aeruginosa incorporating Dettol or cetrimide. It is sensitive to acids, beta glutaraldehyde, silver salts and strong phenolic disinfectants. Its susceptibility to silver has been applied clinically in the use of silver sulphonamide compounds as topical cream in burns.

11. Laboratory diagnosis The bacterium grows readily on the most media. The identification of pigmented strains of the bacillus from clinical specimens is easy. But about 10 percent of isolates may be nonpigmented. It may be necessary to use selective media such as cetrimide agar for isolation from feces or other samples with mixed flora. Repeated isolation help to confirms diagnosis.

12. How is a Pseudomonas aeruginosa infection diagnosed? A healthcare provider can diagnose a Pseudomonas aeruginosa infection after reviewing your medical history, asking about your symptoms and conducting a physical examination, which may include: Using a stethoscope to listen to your heart and lungs (auscultation). Feeling your abdomen. Examining your skin. Looking at your eyes. They'll also order tests to confirm their diagnosis. What tests will be done to diagnose a Pseudomonas aeruginosa infection? A healthcare provider may order imaging tests to look for signs of infection in other areas of your body. These tests may include: X-rays. Ultrasound. Magnetic resonance imaging (MRI).Computed tomography (CT) scan. They may also take body fluid or tissue samples and send them to a lab to look for Pseudomonas bacteria.

13. control Prevention of Ps aeruginosa cross-infection in hospitals requires constant vigilance and strict attention to asepsis. Antibiotic treatment is not always satisfactory. Pseudomonas vaccines are being tried in cystic fibrosis patients who are highly vulnerable to pseudomonas infection. Specific antibacterial therapy constitutes only one aspect of the management of serious pseudomonas infections. Occasional opportunist infection may be caused by a few other species, such as Ps. Fluorescens and Ps. putida.

14. Treatment Ceftazidime is the drug of choice, along with cotrimoxazole , tetracycline, amoxycillin clavulanate, or chloramphenicol . Prolonged treatment, for many months may be necessary. Several types of vaccines are being tested, but none is currently available for general use. REFERENCE Ananthanarayanan and panikers Text book of Microbiology.