Bordetella pertussis. Coloured Transmission Elec- tron Micrograph (TEM) of whooping cough bacteria, Bordetella pertussis. These Gram-negative bacilli have been cut through, showing an outer cell wall and internal DNA genetic material (yellow). They cause whooping cough, known as pertussis, mainly in infants. This infectious disease of the res- piratory tract produces fits of coughing that end in loud inspiratory whoops. Potentially fatal in newborn and premature babies, these bacteria are spread in coughed droplets. Antibiotic drugs have a limited effect and the disease must run its course; a pertussis vaccination is effective. Magnification: x9,000 at 6x4. 5cm size.