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Pseudomonas
Pseudomonas are aerobic, Gram-negative bacteria primarily responsible for hospital-acquired infections, with Pseudomonas aeruginosa being the most notable pathogen. This bacterium is highly resistant to antibiotics, can cause severe infections in immunocompromised individuals, and is associated with high case fatality rates. Laboratory diagnosis typically involves culture on selective media, with treatment options being limited due to increasing antibiotic resistance.
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Overview of the bacteria Pseudomonas by Dr. Roma Goyal, highlighting the significance of this genus in microbiology.
Discusses the family Pseudomonadaceae, detailing aerobic, non-spore forming characteristics, and hospital-acquired infections.
Identifies important species causing human infections including Pseudomonas aeruginosa and Burkholderia species.
Describes Pseudomonas aeruginosa morphology including its size, motility, and presence of a mucoid slime layer.
Growth conditions across various media like nutrient agar and blood agar, emphasizing temperature range and colony characteristics.
Details the production of pigments by Pseudomonas strains, including Pyocyanin, Pyoverdin, Pyorubin, and Pyomelanin.
Biochemical tests like O/F test, oxidase, catalase, and nitrate reduction to characterize Pseudomonas metabolism.
Explains Pseudomonas resistance to temperature and disinfectants, detailing specific resistance to antibiotics.
Discusses hospital-acquired infections, susceptibility factors, prevalent infections, and high fatality rates in certain patient groups.
Specimens for diagnosis and characteristics observed in culture media including nutrient agar and blood agar.
Methods for identifying Pseudomonas via microscopy, biochemical tests, and antibiotic sensitivity testing.
Treatment challenges due to antibiotic resistance; common effective antibiotics and absence of vaccines.
Prevention strategies against Pseudomonas infections, highlighting vulnerable patient populations and cross-contamination risks.
Introduces other clinically significant species of Pseudomonas such as Pseudomonas putida and fluorescens.
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Pseudomonas
- 1. Pseudomonas Dr. Roma Goyal AssistantProfessor Department of MIcrobiology 1
- 2. • Family Pseudomonadaceae –Aerobic, non-spore forming Gram negative straight or slightly curved rod (1 to 3 um in length) – Motile with polar flagella – Non-fermenters – Catalase and oxidase positive – Pigment producing bacteria. – Mostly causes Hospital acquired infection. – Opportunistic pathogens, majorly found in soil, water and sevage. – They are highly resistant to chemical disinfectants, antibiotics. What are Pseudomonas
- 3. • The mostimportant pseudomonad species responsible for human infections are Pseudomonas aeruginosa, Burkholderia pseudo mallei and members of the Burkholderia cepacia compleDxr.T..
- 4. Pseudomonas aeruginosa • Morphology •They are slender gram negative bacillus, 1.5 – 3 microbes x 0.5 microns • Actively motile by polar flagella • some are pilated • Non capsulated but many strains have mucoid slime layer. 4
- 5. Cultural Characters 5 • Obligateaerobe • Growth occurs at wide range of temperatures 6-42oC the optimum being 37oC • Growth on ordinary media producing large opaque irregular colonies with earthy smell. • In broth forms dense turbidity with surface pellicle.
- 6. • Nutrient agar- Colonies are smooth, large, translucent, low convex, 2-4mm in diameter. Produce sweetish aromatic odor Greenish blue pigment diffuses 6
- 7. Growth on • Bloodagar Similar to nutrient agar Many are haemolytic • Mac conkey agar Colourless,non lactose fermenters • Cetrimide agar selective media 7 Blood agar Non lactose fermenting colonies on MacConkey agar Cetramide agar
- 8. MacConkey Agar P. aeruginosaMucoid P. aeruginosa
- 9. Pigment production Some strainsproduce diffusible pigments: • Pyocyanin Bluish green phenazine pigment Soluble in chloroform and water Not produced by other species It is diagnostic of Pseudomonas aeruginosa • Pyoverdin(fluorescein) It is a greenish yellow pigment Insoluble in chloroform but soluble in water Produced by many other species 9 Pyocyanin Pyoverdin
- 10. • Pyorubin Reddish brownpigment Insoluble in chloroform but soluble in water • Pyomelanin Brown to black pigment Production is uncommon 10
- 11. Biochemical reactions O/F test-oxidative Catalase-positive Indole,MR and VP and H2S tests are negative Oxidase-positive Nitrate reduction-positive Citrate test-positive 11 Oxidase test Catalase test Citrate test
- 12. Resistance 12 • Killed at55°C in 1 hour • High resistance to chemical agents • Resistance to quaternary ammonium compounds. Chlorxylenol • Grows also in antiseptic bottles • Dettol and Cetrimide as selective medium(Cetrimide agar) • Sensitive to acids silver salts, (Uses as tropical cream in burns.) • Intrinsically resistant to commonly used antibiotics.
- 13. • Common causeofhospitalacquired infection. • P.aeruginosa can infect almost any external site or organ. • P.aeruginosa is invasive and toxigenic. It attaches to and colonizes the mucous membrane or skin, invade locally, and produces systemic diseases and septicemia. • P.aeruginosa is resistant to many antibiotics. It becomes dominant when more susceptible bacteria of the normal flora are suppressed.
- 14. • Extremely broadhost spectrum • Hardly any infections in the normal human host • Severe immunodeficiencies and medical devices predispose the patients to P.aeruginosa infections • Broad spectrum of clinical symptoms – Urinary tract infections – Pulmonary infections – Soft tissue infections – Sepsis – Bone and joint infections – Endocarditis
- 15. 15 Who are moresusceptible to infection • This bacterium is of particular concern to individuals with cystic fibrosis who are highly susceptible to pseudomonas lung infections. • Pseudomonas aeruginosa is also of grave concern to cancer and burn patients as well as those people who are immunocompromised. • The case fatality rate for individuals infected with Pseudomonas aeruginosa approaches 50 percent.
- 16. Laboratory diagnosis Specimens: • Wounddischarge • sputum • Blood • Urine • CSF • Pus
- 17. On nutrient agar •Colonies are smooth, large, translucent • Greenish blue diffusible pigment Culture On blood agar • Grayish colonies • Many are haemolytic (beta hemolysis).
- 18. On MacConkey agar •Non-lactose fermenting (colourless colonies)
- 19. Pigment production onCetrimide agar • is a type of agar used for the selective isolation of the gram-negative bacterium, Pseudomonas aeruginosa. • As the name suggests, it contains cetrimide, which is the selective agent against alternate microbial flora. Pseudomonas aeruginosa fluorescence under UV illumination
- 20. Microscopy -Gram staining Gram negativebacili seen. -Hanging drop preparation: Actively Motile
- 21. Oxidase test • Oxidasepositive Catalase test • Catalase positive Biochemical Reactions Automated methods VITEK test: for identification and antibitic sensitivity of bacteria Molecular methods The bacterial genome can be identified by PCR.
- 22. Antibiotic senstivity testing Helpfulto select out appropriate antibiotic for treatment.
- 23. 23 Treatment of P.aeruginosa infections • P.aeruginosa is frequently resistant to many commonly used antibiotics. • Although many strains are susceptible to gentamicin, tobramycin, colistin, and amikacin, resistant forms have developed. • The combination of gentamicin and carbenicillin is frequently used to treat severe Pseudomonas infections. • No vaccines so far
- 24. Prevention and Control Pseudomonasspp. normally inhabit soil, water, and vegetation and can be isolated from the skin, throat, and stool of healthy persons. Spread is mainly via contaminated sterile equipment's and cross-contamination of patients by medical personnel. 24
- 25. • High riskpopulation: patients receiving broad-spectrum antibiotics, with leukaemia, burns, cystic fibrosis, and immunosuppression. • Methods for control of infection are similar to those for other nosocomial pathogens. Special attention should be paid to sinks, water baths, showers, hot tubs, and other wDer.T.tV.Raao Mreas. 70
- 26. Other Pseudomonas Clinicallyrelevant pseudomonas in increasing percentage are: Pseudomonas putida Pseudomonas stutzeri Pseudomonas flurescens