Respiratory System Infections

M^J ebecca Lancefield's mother was a direct descendent ■ of Lady Mary Wortley Montagu, who promoted smallpox JL. m. variolation in England more than 75 years before Jenner.

Lancefield was educated in various schools as her parents moved from one army base to another. In 1912, she entered Wellesley College and became interested in biology. She was awarded a scholarship to Columbia University and studied under the famous microbiologist Hans Zinsser, a pioneer in the science of immunology. She received a Master's degree, but her studies were interrupted when her husband was drafted into the armed services in World War I. Fortunately he was assigned to the Rockefeller Institute, where Rebecca got a job as a laboratory technician for the distinguished microbiologists O. T. Avery and A. R. Dochez.

Well known for their studies ofpneumococci, Avery and Dochez had been commissioned to study streptococcal cultures from personnel at army camps. At that time, classification of the numerous kinds of streptococci was based largely on whether their colonies on blood agar produced b-hemolysis or a green discoloration. By using different strep tococcal strains to immunize mice and produce antisera, Avery and Dochez showed that their cultures could be divided into groups based on their antigens. Later, the Lancefields returned to Columbia, where Rebecca received her Ph.D. in 1925for her studies of a-hemolytic streptococci. At that time, a-hemolytic streptococci were considered a possible cause of rheumatic fever, a common cause of serious heart disease, but she showed that these streptococci occurred just as often in healthy people as in those with rheumatic fever. Thereafter, Rebecca returned to the Rockefeller Institute where she spent the remainder of her scientific career studying streptococci. Building on the discoveries of others, she showed that almost all the strains of b-hemolytic streptococci from human infections had the same cell wall carbohydrate "A." Streptococci from other sources had different carbohydrates: "B" from cattle infections; "C" from cattle, horses, and guinea pigs; "D" from cheese and human normal flora; and so forth. The grouping of streptococci by their cell wall carbohydrates, now referred to as "Lancefield grouping," proved to be a much better predictor of pathogenic potential than hemolysis on blood agar. Lancefield, in 1960, became the first woman president of the American Association of Immunologists. In 1970, Lancefield was elected to the prestigious National Academy of Sciences. She died in 1981 at the age of 86. ■ Mary Wortley Montagu, p. 419

—A Glimpse of History

RESPIRATORY INFECTIONS ENCOMPASS AN ENORmous variety of illnesses ranging from the trivial to the fatal. For convenience, they can be divided into infections of the upper part of the respiratory system, primarily the head and neck, and infections of the lower respiratory system, in the chest. Most upper respiratory infections are uncomfortable, but not life threatening and go away without treatment in about a week. However they are so common that they far outweigh other infections in terms of the cumulative misery they cause. Some illnesses, such as the childhood rashes discussed in chapter 22, have a minor upper respiratory component but injure the skin, lung, nervous system, or other parts of the body. Still others cause major symptoms involving the eye, nose, throat, middle ear, sinuses, and other body systems. The lower respiratory system is usually sterile, well protected from colonization by microorganisms. However pathogens sometimes evade the body's defenses and cause serious diseases, such as pneumonia, tuberculosis, or whooping cough.

562 Chapter 23 Respiratory System Infections

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