GRAM POSITIVE, HIGH G+C

TFC, 2nd, p 275-299, 7^th: pp324-325, 8^th: 324-326 also Jensen & Wright, Medical Microbiology

Bergey's Manual of Systematic Bacteriology, (1984) four volumes (See p. 756 for overview)

and Black, Microbiology Principles and Applications., Bauman 2^nd: 550-561

Rvsd 8 August 1993, 8 Aug 1994, 8 Aug 01, 28 Feb 02, 31 July 2002, 1 Aug 03, 9 Aug 04,3Aug07

IRREGULAR, NON-SPORULATING GRAM-POSITIVE RODS

Listeria monocytogenes (P 551) intracellular parasite, grows inside mammalian cell, hidden from immune system.

       Rarely pathogenic except in susceptible Pts (including pregnant females, newborns, elderly, immune compromised.

       Ubiquitous, but especially undercooked meat and veggies, raw milk, soft cheese.

Corynebacterium diphtheriae               club shaped bacteria (p. 551) (club-rod, two membranes)

toxin lysogen-derived, interferes with protein synthesis in body, damages heart, kidneys, NS produce sequella.

Transmitted by droplet aerosols, pseudomembrane forms of bacilli, damaged epithelial and blood cells, and fibrin. Prevented with toxoid (DPT).

Mycobacteria    Cell envelopes contain large amounts of lipid: acid-fast. Slender rods, most soil saprophytes. Resistant to antibiotics: mycolic acid (wax-like molecule) in cell wall, tubercles wall off

       Mycobacteria tuberculosis  p 554: consumption.

1/3rd (1.5 billion) infected in world. Koch discovered cause in 1882. Cell wall lipids (acid fast) protect fr host defenses. Obligate aerobe, needs high O₂. Long division time (18 hrs) insidious onset. Reproduce inside WBC, lyse, release more, spread, cause inflammation, massive necrosis or solidify to granulomas

tubercles: walled off by host macrophages, collagen, then calcified, viable for years, visible by X ray. Cause bloody sputum. If tubercles break, bacilli disseminate: miliary (small grains) tuberculosis.

             Test:    Mantoux Test: inject tuberculin (fr cell wall): induration, reddening (bump is delayed hypersensitivity = previous exposure. (P 555)

             Vaccine:          BCG (Bacillus of Calmette and Guerin)

             Treatment        isoniazid, (inhibits synthesis of mycolic acids), rifampin (inhibits mRNA synthesis) for 1 yr.

                          New resistant strains (MDR-TB) especially in AIDS patients.

       Mycobacteria leprae           p 557 (Hansen's disease) First bacterium demonstrated to be human pathogen.

Destroys peripheral nerves, skin and mucous membrane. Prefers cooler parts of body.

                          Not highly contagious, only with close continual contact.

                          Two forms:

                                       Tuberculoid (neural), loose sensation, tubercles surround region

                                       Lepromatous (progressive) skin cells infected, mucous cells of nose

OTHER HIGH G+C GRAM POSITIVE BACTERIA

       Propionibacterium acnes  common on skin, cause acne? Same genus in Swiss cheese,

       Gardnerella vaginalis         highly pleomorphic. one of most common causes of vaginitis.

ACTINOMYCETES: filamentous, v. common in soil, smell of soil due to these. Two important as source of antibiotics

NOCARDIOFORMS:            aerobic, rudimentary filaments, Gm + pleomorphic, aerobic, usually acid-fast

       Nocardia asteroides:         pulm. nocardiosis, destroy feet, hands (note similarity of diseases to Mycobacterium)

       Actinomyces israelii           (ray fungus) branching filaments, mainly soil, some in mouth. Some cause jaw abscesses, dental caries or periodontal infections. A. israelii causes actinomycosis of head, neck or lungs: tissue destroying

       Streptomyces           None pathogenic. Produce over 500 different antibiotics some effective against bacteria, viruses, protozoans and fungi.

       Propionibacterium acnes  In Swiss cheese, common on skin, cause acne?

       Gardnerella vaginalis         highly pleomorphic. one of most common causes of vaginitis.