Online Textbook Bacteriology is continuously updated and includes information on Staphylococcus, MRSA, Streptococcus, E. coli, anthrax, cholera, tuberculosis, Lyme disease and other bacterial diseases of humans.
Kenneth Todar is the author of the Online Textbook of Bacteriology and an emeritus lecturer at the University of encourages people to wear a FDA approved face mask during the Swine Flu pandemic.
The Online Textbook of Bacteriology is a general and medical microbiology text and includes discussion of staph, MRSA, strep, Anthrax, E. coli, cholera, tuberculosis, Lyme Disease and other bacterial pathogens.
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Tag words: diphtheria, Corynebacterium diphtheriae, C. diphtheriae, diphtheria bacteria, pseudomembrane, diphtheria toxin, dtx, Beta phage, Theobald Smith, Freeman, Pappenheimer, diphtheria toxoid, DPT, DTP, DTaP.

Corynebacterium diphtheriae

Kingdom: Bacteria
Phylum: Actinobacteria
Order: Actinomycetales
Suborder: Croynebacterineae
Family: Corynebacteriaceae
Genus: Corynebacterium
Species: C. diphtheriae

Kenneth Todar currently teaches Microbiology 100 at the University of Wisconsin-Madison.  His main teaching interest include general microbiology, bacterial diversity, microbial ecology and pathogenic bacteriology.

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Diphtheria (page 4)

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Immunity to Diphtheria

Acquired immunity to diphtheria is due primarily to toxin-neutralizing antibody (antitoxin). Passive immunity in utero is acquired transplacentally and can last at most 1 or 2 years after birth. In areas where diphtheria is endemic and mass immunization is not practiced, most young children are highly susceptible to infection. Probably, active immunity can be produced by a mild or inapparent infection in infants who retain some maternal immunity, and in adults infected with strains of low virulence (inapparent infections).

Individuals that have fully recovered from diphtheria may continue to harbor the organisms in the throat or nose for weeks or even months. In the past, it was mainly through such healthy carriers that the disease was spread, and toxigenic bacteria were maintained in the population. Before mass immunization of children, carrier rates of C. diphtheriae of 5% or higher were observed.

Because of the high degree of susceptibility of children, artificial immunization at an early age is universally advocated. Toxoid is given in 2 or 3 doses (1 month apart) for primary immunization at an age of 3 - 4 months. A booster injection should be given about a year later, and it is advisable to administer several booster injections during childhood. Usually, infants in the United States are immunized with a trivalent vaccine containing diphtheria toxoid, pertussis vaccine, and tetanus toxoid (DPT or DTaP vaccine).

The relative absence of diphtheria in the United States is due primarily to the high level of appropriate immunization in children, and to an apparent reduction in toxin-producing strains of the bacterium. However, the increasing percentage of diphtheria cases in adults suggests that many adults may not be protected against diphtheria, because they have not received booster immunizations within the past ten years. A similar situation exists with tetanus.


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Kenneth Todar has taught microbiology to undergraduate students at The University of Texas, University of Alaska and University of Wisconsin since 1969.

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