Pseudomonas aeruginosa is the bacteria of my initial unknown project. Determining which bacteria I had was completed by many steps. The one fact that I had, was that it was a gram negative bacteria because on the gram stain it appeared pink. Its cell wall is composed of a plasma membrane, periplasmic space, peptidoglycan and an outer membrane (lipopolysaccharide and protein). By looking at the agar plate it was easy to tell that it was not a swarmer and it did not have any colony pigment. It appeared as a circular, raised, undulated bacterium. The arrangement of Pseudomonas aeruginosa is rod shaped.
Multiple biochemical tests can be performed to determine if gram positive or negative. See Table below: Oxidase Purple-Blue= pos Catalase Bubbles=pos Urease Lack of color change= neg SIM No black=No conversion= neg, If no color change after Kovacs Reagent added= neg No growth seen around the line of inoculation motility= neg Glucose Fermentation Broth & O/F Medium No fermentation of glucose Carbohydrate Fermentation MRVP Methyl Red; if color changes from red to yellow= neg Voges Proskauer;
If it changes to a light brown= neg Citrate If media turns bright blue= pos Gelatin Hydrolysis If medium liquefied even after refrigerated= pos Siderophore Production Stimulates production of flourescein and reduces that of pyocyanin and/or pyorubin HCN Production A change in the color of the filter paper from yellow to dark brown.
PSEUDOMONAS AERUGINOSA 3 Problems that may arise with testing could be that the bacteria being tested could be specimen contamination or the specimen may require multiple tests to determine which bacteria that it is resulting in higher cost and greater contamination probability. Pseudomonas aeruginosa is a member of the Gamma Proteobacteria class of bacteria. It is a gram negative bacteria, aerobic rod belonging to the bacteria family Pseudomonadaceae.
It is a free living bacterium commonly found in soil and water. Pseudomonas aeruginosa is an opportunistic pathogen, meaning that it exploits some break in the host defenses to initiate an infection. The bacterium almost never infects uncompromised tissues, yet there is hardly any tissue that it cannot infect if the tissue defenses are compromised in some manner. Burn victims and people with puncture wounds may get dangerous pseudomonas infections of the blood, bone, or urinary tract. The bacteria can also get into the body through IV needles or catheters.
Motility occurs via flagella, and retractile pili. Adhesins occur by way of pili and alginate slime. These bacteria like moist environments, such as hot tubs and swimming pools, where they can cause a skin rash or swimmer’s ear. People who wear contact lenses can get serious eye infections if the bacteria get into their contact lens solutions. This can happen if you aren’t careful about keeping your contact lenses and equipment sterile. It causes urinary tract infections in people with Foley catheters, respiratory system infections in people with mechanical ventilation, dermatitis, soft tissueinfections, bacteremia, bone and joint infections, gastrointestinal infections and a variety of systemic infections, particularly in patients with severe burns and in cancer and AIDS patients who are immunosuppressed.
(Giamarellou) Pseudomonas aeruginosa is naturally resistant to a large range of antibiotics. This makes treatment for such bacteria very difficult at times, PSEUDOMONAS AERUGINOSA 4 especially with certain patient allergies. In hospitals, where the most serious infections occur, Pseudomonas can be spread on the hands of healthcare workers or by equipment that gets contaminated and is not properly cleaned, hence why infection control in-services are vital to patient safety.
Toxins produced by Pseudomonas aeruginosa include, Exoenzyme S, Exotoxin A, Lipopolysaccharide. Exotoxin A has exactly the same mechanism of action as the diphtheria toxin; it causes the ADP ribosylation of eucaryotic elongation factor 2 resulting in inhibition of protein synthesis in the affected cell. It utilizes a different receptor on host cells than diphtheria toxin, but otherwise it enters cells in the same manner and has the exact enzymatic mechanism.
The production of Exotoxin A is regulated by exogenous iron, but the details of the regulatory process are distinctly different in C. diphtheriae and P. aeruginosa. Exotoxin A appears to mediate both local and systemic disease processes caused by Pseudomonas aeruginosa. It has necrotizing activity at the site of bacterial colonization and is thereby thought to contribute to the colonization process. Toxinogenic strains cause a more virulent form of pneumonia than nontoxinogenic strains. In terms of its systemic role in virulence, purified Exotoxin A is highly lethal for animals including primates.
Indirect evidence involving the role of exotoxin A in disease is seen in the increased chance of survival in patients with Pseudomonas septicemia that is correlated with the titer of anti-exotoxin A antibodies in the serum. Also, tox- mutants show a reduced virulence in some models.
References: I. Giamarellou, H.(2002). Prescribing guidelines for severe Pseudomonas infections. Journal of Antimicrobial Chemotherapy, 49(2), 229-233. doi:10. 1093/jac/49. 2. 229 II. Lin, M. & Chen, Y. (2006). Pseudomonas aeruginosa Bacteremia: Treatment and Outcome- An Analysis of 56 Episodes. Infectious Diseases in Clinical Practice, 14(3), 150-153. doi:10. 1097/01. idc. 0000202257. 34927. a2 III. Lister, P. D. , Wolter, D. J. , & Hanson, N. D. (2009). Antibacterial- Resistant Pseudomonas aeruginosa: Clinical Impact and Complex Regulation of Chromosomally Encoded Resistance Mechanisms. Clinical Microbiology Review, 22(4), 582-610. Doi:10. 1128/CMR. 00040-09.