Microbiology 3302 Spring 2013 – Getting Friendly with Bacteria

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    Tanisha
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    Greetings! I go by the name Pasteurella multocida. Welcome to my world! I am a small non-motile, gram negative coccobacillus. My family members (genus) go by the name Pasteurella and some of my friends include other Gammaproteobacteria such as Enterobacteriales, Pseudomondales, Vibrios and Legionallales just to name a few. As a facultative anaerobe, I’m able to grow in both aerobic and anaerobic conditions, although I prefer growing in the presence of oxygen. Iron is my go to essential nutrient and plays a very important role in my energy metabolism and electron transport system. My hosts and I don’t always see eye to eye when it comes to iron levels and therefore only a limited amount of iron is usually available to me. How very inhospitalable of them to put their needs before mine! Not to worry though because I’ve developed special mechanisms encoded in my genes to efficiently acquire, transport, and utilize iron under such conditions.

    When it comes to my hosts, I like variety and therefore do not discriminate. You can find me in a wide range of animals both wild and domesticated. When I’m found in certain animals such as adult cattle, rabbits, pigs, cats and dogs I can oftentimes be quite docile living peacefully among their nasopharyngeal or gingival microflora. On the other hand when I’m feeling particularly rambunctious, my pathogenic abilities come alive. I’ve been known to cause avian and fowl cholera, pulmonary infections in cattle, as well as life threatening pneumonia in rabbits. I especially take pride in being able to wipe out complete flocks and herds of previously healthy animals. With the help of dog and cat bites, I even get the privilege of infecting humans which is always a pleasant treat. Infected bites usually cause a severe abscess which becomes very inflamed and can lead to cellulitis.

    I have two key virulent factors which contribute to my pathogenicity: my capsule and lipopolysaccharide (outer membrane layer). My capsule plays a very important role of helping me to avoid phagocytosis and resist “complement mediated lysis” which the immune system of my ungrateful host uses to try and get rid of me. My lipopolysaccharide serves as the protective agent needed so that I can replicate and cause disease in my hosts. In addition certain strains are even capable of producing a toxin known as PMT which causes atrophic rhinitis in pigs.

    If you care to culture me, I grow “readily on nutrient blood agar to produce, nonhemolytic iridescent colonies, I show no growth on MacConkey agar and most of my strains ferment only glucose and sucrose with no gas production” (Collins). Lastly by no means do I condone such actions but I’m susceptible to mild heat (55 °C) as well as antibiotics such as sulfadiazine, ampicillin, chloramphenicol, and tetracycline.

    References:
    BacMap Genome Atlas. Pasteurella multocida subsp. multocida str. Pm70
    http://bacmap.wishartlab.com/organisms/41

    Collins, F. M. (1996). Pasteurella, Yersinia, and Francisella. In: Baron S, editor. Medical Microbiology. 4th edition. Galveston, TX: University of Texas Medical Branch at Galveston; Chapter 29 http://www.ncbi.nlm.nih.gov/books/NBK7798/

    Harper, M., Boyce, J. D., & Adler, B. (2006) Pasteurella multocida pathogenesis: 125 years after Pasteur. FEMS Microbiology Letters, 265(1), 1-10. http://onlinelibrary.wiley.com/doi/10.1111/j.1574-6968.2006.00442.x/pdf

    Paustian, M. L., May, B. J., & Kapur, V. (2001). Pasteurella multocida Gene Expression in Response to Iron Limitation. Infection and Immunity, 69(6): 4109 http://iai.asm.org/content/69/6/4109.full.pdf

    Public Health England. (2011). General Information on Pasteurella Infections http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Pasteurellosis/GeneralInformation/

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