Microbiology and Immunology

WORLD OF MICROBIOLOGY AND IMMUNOLOGY Loeffler, Friedrich August Johannes

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1879, when he moved to Berlin and continued his work at the

Kaiserliches Gesundheitsamt.

Friedrich Loeffler’s transfer brought him under the

supervision of Robert Koch. Loeffler and Georg Graffky

began assisting Koch on his research of bacteria. Loeffler first

began his bacteriological studies researching effective meth-

ods of disinfection. During his studies, Loeffler discovered

Loefflerella mallei,bacteria that causes glanders, a disease

seen mainly in horses. To determine the exact bacteria that

causes glanders, Loeffler applied what has come to be known

as Koch’s postulates. Initially, Loeffler isolated the infectious

agent from the horse and grew it in a pure cultureof blood

serum. Next, Loeffler injected the bacteria into healthy horses,

which then showed symptoms of the disease. Finally, Loeffler

once again isolated the bacteria from the once healthy horses.

In addition to discovering Loefflerella mallei,Loeffler discov-

ered the infectious agent that causes cholera in swine.

In 1884, after a long struggle to decipher the etiological

agent that causes diphtheria, Loeffler isolated Corynebac-

terium diphtheriaein pure culture from the throat of humans.

Problems pinpointing the exact microorganism that causes

diphtheria stemmed from the fact that many different microor-

ganisms inhabited the throats of diphtheria patients. Loeffler

undertook the task of isolating pure cultures of bacteria to

determine the exact etiological agent of diphtheria. Loeffler

found that certain throat infections were due to streptococcal

infections, which are now known to cause scarlet fever. He

reasoned that the Streptococcusbacteria were not responsible

for causing diphtheria because when injected into healthy ani-

mals, the bacteria did not produce symptoms characteristic of

the disease. Additionally, the Streptococcuswas not always

abundant in diphtheria patients. The Streptococcusappeared to

be secondary to rod shaped bacteria. When these rod shaped

bacteria, called bacillus, were isolated in pure culture and

injected into healthy animals, the animals exhibited the char-

acteristic signs of human diphtheria, including the

pseudomembrane in the throat of the patients that suffocate to

death. Additionally, Loeffler determined that toxins produced

by the infectious agent were the cause of destruction to inter-

nal organs. He reasoned that the toxins released entered the

blood stream and traveled to other organs thereby poisoning

them. Emile Roux and Yersin proved this theory of toxins to

be correct. Loeffler made a surprising discovery when he was

able to isolate the diphtheria bacillus from healthy individuals.

He then determined that not all people who carry infectious

microorganisms contract the disease.

Also in 1884, Loeffler began his new career as hygienic

director with his first directorship position being at the First

Garrison Hospital. There he was able to continue his bacterio-

logical research in conjunction with lecturing on sanitation.

Two years later, he became part of the faculty at the University

Joseph Lister (right) pioneered the use of antibacterial techniques in hospitals, including the use of disinfectant spray during operations.

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