Aerobes
Rods & Cocci

• Highly oxidative pseudomonads (Pseudomonas, xanthomonas)
• Nitrogen fixers (Rhizobium & Azotobacter)
• Acetate producers (Gluconobacter & Acetobacter) usually saprophytes
• Legionella (pathogens)
• Neisseria (pathogens)
• Methylotrophs (specialized C1 utilizing bacteria)
• Other aerobic rods (Brucella, Bordetella, Francisella)

Pseudomand group

• Mainly soil (eg Pseudomonas) & plants (Xanthomonas)
• Motile by polar flagella (Pseudomonas)
• Saprophytes (Pseudomonas), Opportunistic pathogens (P. aeruginosa), plant pathogens (Xantomonas, P. syringae)
• Saprophytic Pseudomonas metabolically versatile (>100 organic compounds utilized) & important in mineralization processes & pesticide degradation; anaerobic growth with nitrate leads to denitrification (loss of N2)
• Highly oxidative (oxidase +ve ie high levels of cytochrome oxidase; respirers)
• Produce water soluble pigments (identification feature) eg Pseudomonas
• Produce water insoluble pigments (eg Xanthomonas= plant pathogens)

Pseudomonas aeruginosa

• Opportunistic pathogen (burn victims, hospital environment & nosocomial infections).
• Hospital evironment growth in traces of unusual compounds (eg soap residues, quaternary ammonium compds); fibre-optic gastrointestinal endoscopes contamination
• Antibiotic ressistance due to porins (LINK porins) & plasmid borne genes (R genes, LINK)-- chemotherapy complications
• Produce soluble blue-green pigments (identification feature)

Pseudomonas mallei

• Glanders disease in horses

Pseudomonas syringae

• Phytopathogen, chlorotic lesions

Pseudomonas solancearum

• Phytopathogen, plant wilting

Nitrogen fixers

• Soil habitat
• Growth aerobic, N2 fixation anaerobic (fixation independent of growth)
• Free living fixers (Azotobacter & cysts (LINK) of tropical & acid soils
• Symbiotic fixers in root nodules (Rhizobium= fast growers; Bradyrhizobium= slow); Differs from Agrobacterium (crown galls= uncontrolled tumor growth; harmful), host- vectors for introducing genes into plants.

Acetate producers

• Important in the production of cider & vinegar (acetate, acetic acid)

  [Gluconobacter, Acetobacter]

• Organic acid (eg D-sorbitol, ethanol)-->Org acids & keto alcohols (eg L-sorbose, acetate)

  [Steriospecific single step oxidation by Gluconobacter]

• Cellulose microfibres as an alternative source for fabric & paper manufacture
  

  [Acetobacter xylinum]

• Glycerol----------> Dihydroacetone (sun taning agent)
  

  [Acetobacter species]

• Sorbitol ------------>Sorbose -------->Ascorbic acid, Vitamin C
  

  [Gluconobacter] [Other bacteria]

Legionella

• Rods to filaments
• 1976 Legionaires disease (Legionella pnuemophila); some 26 species and 41 serotypes. But only a few are pathogens; Kochs postulates (LINK to Koch)
• Natural aquatic habitats & artificial aquatic habitats (eg cooling towers); virulence induced due to warmth in artificial habitats (eg more viruelent strains at 42 than at 30)
• Fastidious (pathogen or nonpathogen), requires L-cysteine; antibacterial agents (vancomycin, polymyxin, glycine) & charcoal (remove media impurities) added to complex media; no growth in blood agar plates (Streptococci growth medium); Selection using antibiotics (LINK Rifampin in spirochetes)
• Induction of virulence due to warming of water
• Legionella puemophila transmitted via air from sprays of showerheads
• Same species causes different symptoms depending on the health of individual (Legionaires disease peumonic, life threatening) but pontiac fever (non-pneumonic, not life threatening)
• Australian Experiences with Legionella
• In outback communities, high levels of Legionella antibodies but no symptoms. Why?
• Legionella & potting mix

Neisseria

• Neisseria (diplococci, capsulated (LINKS) with pili & fimbriae LINKS) the most important pathogen with mucosal membranes as primary sites of infection
• Gonorrhoea is a STD & communicable disease; N. gonnorrhoeae Pencillinase Producing (PPNG) strains are of concern
• N. meningitidis found in throats of healty carriers; infect membrane of nasopharynx followed by invasion into blood & spinal fluid to cause meningitis (inflamation of meninges, membrane around spinal cord & brain); symptoms due to endotoxins (LINKS); children more susceptible; Purified capsular polysacharide vaccines given to new military recruits to prevent epidemics

Methylotrophs

• Utilize C1 compounds (methane, methanol) as energy & carbon source
• Curved rods (Methylomonas) or cocci (Methylococcus)
• Complex extensive internal membranes the sites of metabolism (membrane LINKS)
• Some produce cysts (LINK), some exospores (small buds from mother cells)
• Potential source of proteins [Single Cell Protein (SCP) from CH4] for human & animals

Other Aerobic Rods:

• Brucella
  • Animal & human parasites; identified on basis of their primary host
    • B.abortus-- infects cattle
    • B. canis-- infects dogs
    • B. suis-- infects pigs.
  • Transmited to humans via contact with infected animals, animal products or contaminated soil
  • Human disease known as undulant fever (=fever reaching 40 C every evening)
  • Economic loss to farmers due to lost meat & milk production
  • Infected cattle identified by agglutination (serum / milk) or by ELISA (specific & sensitive

• Bordetella
  • Bordetella pertusis-- childhood whooping cough (pertusis)
  • Virulent strains capsulated, also endotoxin and exotoxins (LINK)
  • Not invasive but attaches to tracheal cilia inhibiting their function of mucus removal. Mucus accumulation causes violoent coughing which can cause broken ribs. Gasping for air In between coughs causes a whooping sound; more severe in children under 1 yrs.
  • Transmission is airborne during coughing
  • Cultured from swabs obtained during coughing; sensitive to environmental stree & needs quick transfer into growth culture medium
  • Diagnosis is based on an unsatisfactory fluroscent antibody test; DNA tests of interest.
  • Immunization (DPT, P= pertussis, heat inactivated whole bacterium); endotoxins cause fever & is of great concern in these vaccines. Alternatives (purified components) under trial.

• Francisella
  • F.tularensis causes tularemis (discovered 1911, Tulare county USA in ground squirrels)
  • Reservoir is small wild animals.
  • One of several forms exhibited depending on how infection is aquired: Infection aquired by inhalation (pneumonic form), ingestion (throat / mouth) , bites (deer flies, ticks, rabbit lice) or more commonly thro'minor skin breaks. Can cause septecimia.
  • Can survive in phagocytic cells & therefore chemotherapy (streptomycin) is a problem.