Diseases caused by
bacteria. The most common infectious diseases, they range from minor skin infections to bubonic
plague and
tuberculosis. Until the mid-20th century, bacterial
pneumonia was probably the leading cause of death among the elderly. Improved sanitation,
vaccines, and
antibiotics have all decreased the mortality rates from bacterial infections, though antibiotic-resistant strains have caused a resurgence in some illnesses. Bacteria cause disease by secreting or excreting
toxins (as in
botulism), by producing toxins internally, which are released when the bacteria disintegrate (as in
typhoid), or by inducing sensitivity to their antigenic properties (as in tuberculosis). Other serious bacterial diseases include
cholera,
diphtheria, bacterial
meningitis, and
syphilis.
For more information on bacterial diseases, visit Britannica.com.