Microorganism: the bacterium Legionella pneumophila

Disease: legionnaire’s disease

Occurrence of the disease

History: the name of the disease originates from a pneumonia epidemic that occurred in 1976 during a convention of the "American Legion." The bacteria responsible for these pneumonia cases were found to be located in the air conditioning system.

Current situation: in 1988, 104 cases of legionnaire’s disease were reported in Canada, including 26 from the province of Quebec.

Mechanism of action of the disease: when the bacterium reaches the lungs, it becomes a parasite of the lungs' immune cells and releases toxins causing destruction of the nearby tissues.

Symptoms of the disease: high fever, cough, headache, and severe pneumonia

Incubation period: from two to ten days

Contagious period: there is no documentation concerning person to person transmission

Hosts: The reservoirs for this Read More

Microorganism: the bacterium Legionella pneumophila

Disease: legionnaire’s disease

Occurrence of the disease

History: the name of the disease originates from a pneumonia epidemic that occurred in 1976 during a convention of the "American Legion." The bacteria responsible for these pneumonia cases were found to be located in the air conditioning system.

Current situation: in 1988, 104 cases of legionnaire’s disease were reported in Canada, including 26 from the province of Quebec.

Mechanism of action of the disease: when the bacterium reaches the lungs, it becomes a parasite of the lungs' immune cells and releases toxins causing destruction of the nearby tissues.

Symptoms of the disease: high fever, cough, headache, and severe pneumonia

Incubation period: from two to ten days

Contagious period: there is no documentation concerning person to person transmission

Hosts: The reservoirs for this disease are probably aqueous media such as hot water tanks, air conditioning systems, and humidifiers.

Transmission: many studies support the hypothesis that the bacteria might be spread through air. Water aspiration might also be a transmission mechanism.

Treatment: antibiotics such as erythromycin

Geographical distribution of the microorganism: North and South America, Australia, Africa, and Europe

Prevention: periodic cleaning of water tanks and air conditioning systems, use of cleaning products, maintaining hot water at a temperature above 50° C.

Vaccine: not available


© Armand-Frappier Museum, 2008. All rights reserved.

Legionella pneumophila

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Microorganism: the bacterium responsible for leprosy is Mycobacterium leprae.

Disease: leprosy or Hansen’s disease

Occurrence of the disease

History: the first writings describing symptoms similar to those of leprosy come from India around 600 BC. The term "leprosy" is also mentioned in the Old and New Testaments. In 1873, a Norwegian by the name of Armauer Hansen demonstrated that the disease is caused by the bacterium Mycobacterium leprae, which prompted other studies on this disease. Dapsone was used for the first time as a treatment against leprosy in the 1940s. Before that, patients were diagnosed and isolated but no treatment was available.

Current situation: over ten million chronic cases of leprosy are identified around the world but they are mainly concentrated in tropical countries. In 1998 only three cases were reported in Canada.

Forecast: eradication of leprosy is predicted for 2005.

Mechanism of action of the microorganism: the bacteria usually pe Read More

Microorganism: the bacterium responsible for leprosy is Mycobacterium leprae.

Disease: leprosy or Hansen’s disease

Occurrence of the disease

History: the first writings describing symptoms similar to those of leprosy come from India around 600 BC. The term "leprosy" is also mentioned in the Old and New Testaments. In 1873, a Norwegian by the name of Armauer Hansen demonstrated that the disease is caused by the bacterium Mycobacterium leprae, which prompted other studies on this disease. Dapsone was used for the first time as a treatment against leprosy in the 1940s. Before that, patients were diagnosed and isolated but no treatment was available.

Current situation: over ten million chronic cases of leprosy are identified around the world but they are mainly concentrated in tropical countries. In 1998 only three cases were reported in Canada.

Forecast: eradication of leprosy is predicted for 2005.

Mechanism of action of the microorganism: the bacteria usually penetrate into the organism by contact with nasal secretions of an infected person. The bacteria then invade the peripheral nerves including those of the skin skin, usually causing a severe rash.

Symptoms of the disease: pigmented rash followed by death of the cutaneous tissues, which causes a progressive loss of features of the face, fingers, toes, and other structures.

Incubation period: varies between nine months and 20 years

Contagious period: for treated patients, the contagious period lasts about three months.

Hosts: humans

Transmission: the exact mode of transmission is still unknown but prolonged contact with an infected person seems to be an important mechanism by which the disease spreads. Millions of bacteria are released each day in the nasal secretions of patients infected by leprosy.

Treatment: treatment requires a combination of three types of drugs (rifampin, dapsone and clofazimin) because many bacteria are now resistant to drugs used separately. The treatment lasts a minimum of 12 months.

Geographical distribution of the microorganism: certain endemic regions exist in southeast Asia, tropical Africa, and Latin America. However, new cases have been reported in the United States, mostly in California, Florida, Louisiana, and Texas.

Prevention: isolation of untreated patients

Vaccine: not available. However, BCG seems to protect against leprosy.


© Armand-Frappier Museum, 2008. All rights reserved.

Mycobacterium leprae

Armand-Frappier Museum

© Armand-Frappier Museum, 2008. All rights reserved.


Microorganism : the spirochete bacterium Borrelia burgdorferi.

Disease : Lyme disease

Occurrence of the disease

History : Lyme disease was first described in 1975 in Connecticut. The causal agent was identified as Borrelia burgdorferi in 1982.

Current situation : in the United States, where it is endemic to the Atlantic coast, Lyme disease is the most prevalent tick-borne disease, with some 8,000 cases reported annually. In Canada, transmission zones have been identified in Ontario and British Columbia.

Mechanism of action of the microorganism : the bacterium enters the body through a tick bite. It first affects the skin around the bite, then spreads to the nervous system, heart and joints. In the disease’s advanced stage, the bacterium strips the protective coating off nerve cells.

Symptoms of the disease : there are three stages to Lyme disease. In the first stage, the tick bite produces a circular skin lesion, often accompanied by cold-like symptoms such as fatigue, Read More

Microorganism : the spirochete bacterium Borrelia burgdorferi.

Disease : Lyme disease

Occurrence of the disease

History : Lyme disease was first described in 1975 in Connecticut. The causal agent was identified as Borrelia burgdorferi in 1982.

Current situation : in the United States, where it is endemic to the Atlantic coast, Lyme disease is the most prevalent tick-borne disease, with some 8,000 cases reported annually. In Canada, transmission zones have been identified in Ontario and British Columbia.

Mechanism of action of the microorganism : the bacterium enters the body through a tick bite. It first affects the skin around the bite, then spreads to the nervous system, heart and joints. In the disease’s advanced stage, the bacterium strips the protective coating off nerve cells.

Symptoms of the disease : there are three stages to Lyme disease. In the first stage, the tick bite produces a circular skin lesion, often accompanied by cold-like symptoms such as fatigue, malaise, headache, fever, and shivers. During the second stage, which may take several weeks, and even several months, to appear, neurologic symptoms, arthritis, and inflammation of the heart occur. In the final stage, which may take several years to reach, individuals exhibit symptoms similar to those observed in Alzheimer’s disease or multiple sclerosis (demyelinization of neurons).

Incubation period : three to 32 days.

Contagious period : no case of transmission between humans has ever been demonstrated.

Hosts : deer and field mice.

Transmission : both Borrelia burgdorferi and two species of ticks (Ixodes dammini and Ixodes pacificus) usually live on deer and field mice. When the ticks bite these animals, they become hosts to the bacterium, which they transmit to humans when they bite them in turn.

Treatment : some antibiotics, such as penicillin or tetracycline, are effective. Arthritis is less likely to develop if treatment is begun early. In cases of established disease, the use of ceftriaxone may reduce the risk of brain damage.

Geographic distribution of the microorganism : the geographic distribution corresponds to that of the ticks: Canada, the United States, Europe, Russia, China, and Japan.

Prevention : information campaigns concerning the mechanism of transmission of the disease may be helpful, as the risk of catching the disease from a tick bite is highest from May to July. Individuals walking in the woods should take precautions to avoid tick bites. Some insecticides can kill ticks. Self-examination for tick bites may help early diagnosis, allowing the condition to be treated rapidly.

Vaccine : a recombinant vaccine against Borrelia burgdorferi has been available in Canada since 2000 and in the United States since 1999.


© Armand-Frappier Museum, 2008. All rights reserved.

Borrelia burgdorferi

CDC

© CDC


Microorganism: Streptococcus pyogenes

Disease: necrotizing fasciitis (flesh-eating disease)

Mechanism of action of the microorganism: the bacterium usually enters the body through a minor wound such as a cut or bruise, or through a surgical wound. It multiplies in the fascia (the tissues covering the muscles), and produces toxins which destroy them. The dead tissue looks like chewed flesh, giving the disease its popular name.

Symptoms of the disease: the early stages of the disease are characterized by muscle pain, fever, vomiting, diarrhea, and malaise. Other symptoms include a drop in blood pressure, skin rash, and persistent pain at the site of infection. In extreme cases, the disease may result in toxic shock and even death.

There are many strains of Streptococcus pyogenes. While one strain causes necrotizing fasciitis, others are responsible for a variety of diseases, including throat and skin infections, scarlet fever, and rheumatic fever. The symptoms of scarlet fever are skin rash on the trunk, fever, sore throat, and a strawberry ton Read More

Microorganism: Streptococcus pyogenes

Disease: necrotizing fasciitis (flesh-eating disease)

Mechanism of action of the microorganism: the bacterium usually enters the body through a minor wound such as a cut or bruise, or through a surgical wound. It multiplies in the fascia (the tissues covering the muscles), and produces toxins which destroy them. The dead tissue looks like chewed flesh, giving the disease its popular name.

Symptoms of the disease: the early stages of the disease are characterized by muscle pain, fever, vomiting, diarrhea, and malaise. Other symptoms include a drop in blood pressure, skin rash, and persistent pain at the site of infection. In extreme cases, the disease may result in toxic shock and even death.

There are many strains of Streptococcus pyogenes. While one strain causes necrotizing fasciitis, others are responsible for a variety of diseases, including throat and skin infections, scarlet fever, and rheumatic fever. The symptoms of scarlet fever are skin rash on the trunk, fever, sore throat, and a strawberry tongue. Rheumatic fever is an autoimmune disease whose symptoms are inflammation of the joints, the tissues under the skin, and the central nervous system, and damage to the heart valves.

Incubation period: one to three days.

Contagious period: ten to 21 days, although this may be reduced to less than 24 hours if appropriate antibiotic treatment is begun.

Hosts: humans.

Transmission: direct contact with infected persons or with objects contaminated by contact with airborne droplets. Victims may be the host of the bacteria that attack them, as Streptococcus pyogenes is naturally present in some people.

Treatment of the disease: antibiotics, primarily penicillin.

Geographic distribution of the microorganism: worldwide, although some strains are only found in some locations.

Prevention: information campaigns on the mechanism of transmission. Avoidance of situations, such as contact with infected individuals, which favor bacterial transmission.

Vaccine: none.


© Armand-Frappier Museum, 2008. All rights reserved.

Streptococcus pyogenes

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Microorganism: several microorganisms can cause pneumonia, among them the bacterium Streptococcus pneumoniae.

Disease: pneumonia

Occurrence of the disease

History: in industrialized countries, the mortality rate for pneumonia was between 20 and 40% for hospitalized patients.

Current situation: the mortality rate has decreased since the arrival of antibiotic treatments; it is now between five and ten per cent of cases. In developing countries, the mortality rate due to pneumonia caused by S. pneumoniae is often greater than ten per cent and can even reach 60% in children less than six months old.

Mechanism of action of the microorganism: the bacteria S. pneumoniae is naturally present in the respiratory tract of healthy individuals. Alcoholism, smoking, diabetes, injuries, and viral infections are factors that can favor the reproduction of the bacteria in the lungs, more specifically in the alveoli.

Symptoms of the disease: chills, fever, respiratory diffic Read More

Microorganism: several microorganisms can cause pneumonia, among them the bacterium Streptococcus pneumoniae.

Disease: pneumonia

Occurrence of the disease

History: in industrialized countries, the mortality rate for pneumonia was between 20 and 40% for hospitalized patients.

Current situation: the mortality rate has decreased since the arrival of antibiotic treatments; it is now between five and ten per cent of cases. In developing countries, the mortality rate due to pneumonia caused by S. pneumoniae is often greater than ten per cent and can even reach 60% in children less than six months old.

Mechanism of action of the microorganism: the bacteria S. pneumoniae is naturally present in the respiratory tract of healthy individuals. Alcoholism, smoking, diabetes, injuries, and viral infections are factors that can favor the reproduction of the bacteria in the lungs, more specifically in the alveoli.

Symptoms of the disease: chills, fever, respiratory difficulty (dyspnea), rapid breathing, chest pains, cough, rust-colored sputum, i.e., containing blood.

Incubation period: possibly one to three days

Contagious period: as long as the secretions persist

Hosts: humans

Transmission: spread of the disease can occur by contact between an infected person and a healthy person. Transmission is also possible through objects contaminated by the infected person.

Discoverer of the microorganism: Fraenkel in 1886

Treatment: use of antibiotics such as penicillin

Geographical distribution of the microorganism: worldwide

Prevention: avoid crowds in enclosed spaces.

Vaccine: a vaccine composed of bacterial capsules of S. pneumoniae exists and is recommended for women 65 years and older and for people between two and 65 years of age suffering from chronic diseases.


© Armand-Frappier Museum, 2008. All rights reserved.

Streptococcus pneumoniae

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Microorganism : the bacteria Salmonella typhimurium and Salmonella enterica

Disease : salmonellosis

Occurrence of the disease

Current situation : around seven cases of salmonellosis are reported each year in Canada. These are mostly isolated cases; nevertheless, localized epidemics can occur as a result of the distribution of contaminated food products.

Mechanism of action of the microorganism : the bacteria are ingested through the consumption of contaminated food. The microorganism multiplies in the intestine.

Symptoms of the disease : abdominal pain, cramps, diarrhea, fever, nausea, and vomiting.

Incubation period : six to 72 hours.

Contagious period : varies between several days and several weeks.

Hosts : many wild and domestic animals, including poultry, pigs, cattle, and rodents.

Transmission : consumption of contaminated meat.

Treatment : in general, rehydration of the Read More

Microorganism : the bacteria Salmonella typhimurium and Salmonella enterica

Disease : salmonellosis

Occurrence of the disease

Current situation : around seven cases of salmonellosis are reported each year in Canada. These are mostly isolated cases; nevertheless, localized epidemics can occur as a result of the distribution of contaminated food products.

Mechanism of action of the microorganism : the bacteria are ingested through the consumption of contaminated food. The microorganism multiplies in the intestine.

Symptoms of the disease : abdominal pain, cramps, diarrhea, fever, nausea, and vomiting.

Incubation period : six to 72 hours.

Contagious period : varies between several days and several weeks.

Hosts : many wild and domestic animals, including poultry, pigs, cattle, and rodents.

Transmission : consumption of contaminated meat.

Treatment : in general, rehydration of the patient is sufficient. For serious cases, there are antibiotics available, such as cyprofloxacin and ampicillin.

Geographical distribution of the microorganism : worldwide

Prevention : hand washing before and after meal preparation. In addition, adequate cooking of meat is recommended.

Vaccine : not available.


© Armand-Frappier Museum, 2008. All rights reserved.

Salmonella typhimurium

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Learning Objectives

The learner will:
  • familiarize himself with the vocabulary used in microbiology;
  • explain the relationship between developments in imaging technology and the current understanding of the cell;
  • identify which microorganisms are infectious, how the immune system fights against them, and the reinforcements of modern medicine;
  • describe the benefits of microorganisms.

Teachers' Centre Home Page | Find Learning Resources & Lesson Plans