Biomedical Engineering Reference
In-Depth Information
Members of Class Beta Proetobacteria are Gram-negative organisms that
are either aerobic or facultative anaerobic (i.e., employing respiratory metab-
olism when oxygen is present and fermentative metabolism when oxygen is
absent). Class Beta Proteobacteria has two subclasses with organisms that
infect humans: Class Burkholderiales and Class Neisseriales.
Beta Proteobacteria
Burkholderiales
Alcaligenaceae
*Alcaligenes
*Bordetella
Burkholderiaceae
*Burkholderia
Class Burkholderiales
contains Class Alcaligenaceae
and Class
Burkholderiaceae.
Members of Class Alcaligenaceae are found in water and soil and can
infect a range of animals. Class Alcaligenaceaa contains two genera with
organisms infectious in humans: Alcaligenes and Bordetella.
In humans, Genus Alcaligenes contains opportunistic pathogens that
cause disease in immune-compromised patients. Alcaligenes xylosoxidans
has been found in the respiratory tracts of patients with cystic fibrosis, but its
role in respiratory disease is unsettled at this time. Alcaligenes xylosoxidans
can cause corneal keratitis in patients who use contact lenses [31]. Alcaligenes
faecalis has been found in some urinary tract infections.
Bordetella species can infect the respiratory tract of healthy individuals.
Pertussis, also known as whooping cough, is caused by Bordetella parapertussis
and Bordetella pertussis. Bordetella bronchiseptica infects small animals, and
rarely infects humans, producing a bronchitis.
Class Burkholderiaceae contains the genus Burkholderia, which includes
Burkholderia mallei, the cause of glanders, and Burkholderia pseudomallei,
the cause of melioidosis. Glanders is a serious disease, with a high fatality
rate, that is endemic to Africa, Asia, the Middle East, and South America.
It is a zoonosis, with a reservoir in horses and other mammals, spread
through contaminated water (see Glossary item, Zoonosis). An active sur-
veillance system has eliminated the disease from North America. Infected
patients develop lung nodules, upper airway ulcerations, and, eventually,
systemic symptoms. Human-to-human transmission occurs, and infection
can be transmitted from nasal discharge. Survivors of the infection may
become carriers.
Melioidosis, also known as pseudoglanders, is caused by Burkholderia
pseudomallei. Like glanders, it can have a high mortality. The disease is
endemic in Asia and occurs sporadically throughout much of the world. The
organism contaminates soil and water; humans are exposed to the bacteria
through a break in the skin. As you might expect, rice paddy farmers, who
