Microorganism: the bacterium Haemophilus influenzae type b.

Disease: bacterial meningitis

Occurrence of the disease

History: prior to the introduction of a vaccine against Haemophilus influenzae, this microorganism was the greatest cause of bacterial meningitis in children younger than six years old. In 1998, eighteen cases of Haemophilus influenzae type b infection were reported in Quebec.

Mechanism of action of the microorganism: the bacteria multiply in the nasal passages before spreading to the blood and to the liquid surrounding the brain. Once they reach the liquid surrounding the brain, they produce inflammation of the meninges (the membranes surrounding the brain).

Symptoms of the disease: the initial symptoms of meningitis are sore throat, vomiting, headache, confusion, and stiffness in the neck and back. Eventually, meningitis (inflammation of the membrane surrounding the brain) occurs. The mortality rate is five per cent, and 20-45% of survivors suffer serious long-term effects su Read More

Microorganism: the bacterium Haemophilus influenzae type b.

Disease: bacterial meningitis

Occurrence of the disease

History: prior to the introduction of a vaccine against Haemophilus influenzae, this microorganism was the greatest cause of bacterial meningitis in children younger than six years old. In 1998, eighteen cases of Haemophilus influenzae type b infection were reported in Quebec.

Mechanism of action of the microorganism: the bacteria multiply in the nasal passages before spreading to the blood and to the liquid surrounding the brain. Once they reach the liquid surrounding the brain, they produce inflammation of the meninges (the membranes surrounding the brain).

Symptoms of the disease: the initial symptoms of meningitis are sore throat, vomiting, headache, confusion, and stiffness in the neck and back. Eventually, meningitis (inflammation of the membrane surrounding the brain) occurs. The mortality rate is five per cent, and 20-45% of survivors suffer serious long-term effects such as mental retardation and deafness.

Incubation period: unknown, but probably two to four days.

Contagious period: as long as the microorganism is present. When adequate therapy is applied, however, this is reduced to 24-48 hours.

Hosts: humans.

Transmission: contact with nasal secretions from an infected individual.

Discoverer of the microorganism: Weichselbaum in 1887.

Treatment of the disease: antibiotics such as penicillin; 30% of Haemophilus influenzae type b strains are ampicillin-resistant.

Geographical distribution of the microorganism: worldwide.

Prevention: vaccination. Non-vaccinated individuals coming into contact with infected individuals may take Rifampin.

Vaccine: the vaccine currently used against bacterial meningitis is known as the DTP-Polio-Hib vaccine, and is in fact a combination of several vaccines that provides protection against diphtheria, whooping cough, tetanus, polio, and Haemophilus influenzae type b infections. The specific Haemophilus influenzae vaccine (Hib) is produced from bacterial cell walls. The vaccine is more than 90% effective against Haemophilus influenzae infection when administered to children two to five months old. Booster injections of the vaccine must be administered two, four, six, and 18 months after the initial vaccination.

Meningitis may also be caused by other microorganisms, such as the viruses responsible for measles, chickenpox and herpes, and the bacteria Neisseria meningitidis. A vaccination program against Neisseria meningitidis, which causes type c meningitis, was conducted in Quebec in 2001, and resulted in a reduction of the incidence of infection from 1.3/100,000 to 0.3/100,000.


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

Haemophilus influenzae

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Microorganism: genital chlamydiosis is caused by the bacterium Chlamydia trachomatis.

Disease: chlamydia

Occurrence of the disease

Current situation: in Canada, chlamydia is the most prevalent bacterial disease that is sexually transmitted. In 1998, nearly 40,000 people were affected by chlamydia. However, since 1991, the number of reported cases has decreased.

Mechanism of action of the microorganism: the bacteria replicate inside cells in the genital area and cause the cells to burst.

Symptoms of the disease: sterility (inability to produce children) is a possible consequence of genital chlamydiosis. The other symptoms differ between men and women. In women, they consist of an inflammation of the interior of the cervix and the production of mucopurulent endocervical discharge. However, in 70% of cases, women are asymptomatic. In men, chlamydia manifests itself by a burning sensation on urination and itching of the urethra. In men, between one and 25% of cases are also asymptomatic.

Incubatio Read More

Microorganism: genital chlamydiosis is caused by the bacterium Chlamydia trachomatis.

Disease: chlamydia

Occurrence of the disease

Current situation: in Canada, chlamydia is the most prevalent bacterial disease that is sexually transmitted. In 1998, nearly 40,000 people were affected by chlamydia. However, since 1991, the number of reported cases has decreased.

Mechanism of action of the microorganism: the bacteria replicate inside cells in the genital area and cause the cells to burst.

Symptoms of the disease: sterility (inability to produce children) is a possible consequence of genital chlamydiosis. The other symptoms differ between men and women. In women, they consist of an inflammation of the interior of the cervix and the production of mucopurulent endocervical discharge. However, in 70% of cases, women are asymptomatic. In men, chlamydia manifests itself by a burning sensation on urination and itching of the urethra. In men, between one and 25% of cases are also asymptomatic.

Incubation period: possibly seven to 14 days

Contagious period: the contagious period is unknown but is probably intermittent.

Hosts: humans

Transmission: unprotected sexual relations. Chlamydia, which is transmitted by the L1 and L3 serotypes of C. trachomatis, is also known as lymphogranuloma venereum.

Discoverer of the microorganism: Neisser in 1879

Treatment: certain antibiotics such as tetracycline or erythromycin

Geographical distribution of the microorganism: worldwide, however, the disease is more prevalent in tropical regions.

Prevention: use of a condom during sexual relations; detection of the chlamydia-causing bacteria in adolescents and in sexually active young women.

Vaccine: not available


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

Chlamydia trachomatis - a sexually transmitted disease

Illustration by Bruno Laporte

© Illustration Bruno Laporte


Microorganism: the bacterium Vibrio cholerae (subgroup 01)

Disease: cholera

Occurrence of the disease

History: seven major pandemics have been reported, the last of which was in 1961. In 1855 an English doctor, John Snow, discovered that water contaminated by the excrement of persons sick with cholera could be the means of transmission of the disease in England. At that time, two companies shared a monopoly on the distribution of water. Of the 10,000 persons who drank the water of the first company (Southwark and Vauxhall Company), 315 died; among the 10,000 who drank water from the second company (Lambeth Company), only 37 deaths were recorded. In fact, the two companies did not supply water from the same place. The first company supplied water from the Thames, in the heart of London, where the river was polluted by waste from the city. At that period, there was no water treatment. The second company supplied water from the same river, but upstream from the city.

Current situation: in industrialized countries cholera is practically n Read More

Microorganism: the bacterium Vibrio cholerae (subgroup 01)

Disease: cholera

Occurrence of the disease

History: seven major pandemics have been reported, the last of which was in 1961. In 1855 an English doctor, John Snow, discovered that water contaminated by the excrement of persons sick with cholera could be the means of transmission of the disease in England. At that time, two companies shared a monopoly on the distribution of water. Of the 10,000 persons who drank the water of the first company (Southwark and Vauxhall Company), 315 died; among the 10,000 who drank water from the second company (Lambeth Company), only 37 deaths were recorded. In fact, the two companies did not supply water from the same place. The first company supplied water from the Thames, in the heart of London, where the river was polluted by waste from the city. At that period, there was no water treatment. The second company supplied water from the same river, but upstream from the city.

Current situation: in industrialized countries cholera is practically nonexistent; nevertheless, certain regions are still vulnerable, generally because of poor sewage treatment. A few small epidemics (fewer than 300 cases) have been reported in the United States. Researchers believe that these localized epidemics could be related to the consumption of raw mollusks or crustaceans, which form an alternative reservoir of infection. The mortality rate is more than 50% without treatment, but less than one per cent with adequate medical care. At present, fewer than ten cases per year are reported in Canada.

Mechanism of action of the microorganism: the bacterium attaches itself to the intestinal mucous membrane. The bacteria themselves are not invasive, but they produce a poison known as an exotoxin. This poison penetrates the cells that line the intestine and stimulates the excretion of large quantities of water. The sick person becomes dehydrated, and experiences abdominal muscular cramps, vomiting, fever, and liquid diarrhea. An individual may lose from ten to 15 liters of water during the infection. If the dehydration becomes too severe, the infected person may die.

Symptoms of the disease: acute enteritis, cramps, vomiting, severe diarrhea.

Geographical distribution of the microorganism: many countries of central Africa, India, Pakistan, South Korea, Albania, and Malta. Cholera may also spread into southern Europe.

There are two types of cholera: the classic type and the E1 Tor type. Before the 1960s, the classic type was prevalent, whereas now the E1 Tor type is more frequent.

Incubation period: approximately three days

Contagious period: the contagious period lasts as long as the stool contains bacteria, normally several days after the patient is cured.

Transmission: the bacteria are found in food or water contaminated by fecal matter from infected persons.

Hosts: hosts for cholera include mollusks, crustaceans, and plankton.

Discoverer of the microorganism: Robert Koch in 1883.

Treatment: the main treatment for cholera consists of drinking plenty of water with added salt and sugar (sucrose); this allows the intestine to absorb salt and water, which will rehydrate the patient. In addition, some medicines such as antibiotics (streptomycin, tetracycline, trimethoprim-sulfamethoxazole, or ciprofloxacin) can be used. However, these antibiotics are less effective if the patient has not been rehydrated.

Prevention: water treatment

Vaccine: the cholera vaccine is made from parts of the bacterium or from killed bacteria. A booster is required after six months. Vaccination may be recommended in regions where cholera is endemic.


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

Vibrio cholera

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Microorganism: the bacterium Corynebacterium diphteriae.

Disease: diphtheria

Occurrence of the disease

Current situation: in Canada, no cases of diphtheria have been reported for some years. In the United States, fewer than 100 cases of diphtheria are recorded annually, and most of the reported cases occur in individuals who have not been vaccinated.

Projections: in theory, it should be possible to completely eradicate this disease, as humans are the only host.

Mechanism of action of the microorganism: the bacteria enter the respiratory system and excrete a toxin that causes tiny membranes to form in the throat. Diphtheria toxin may also enter the blood and result in the destruction of heart, kidney, and nervous tissue.

Symptoms of the disease: diphtheria affects the throat, usually causing pharyngitis or laryngitis. Other symptoms include high fever, nasal discharge containing pus, and weakness.

Diphtheria may also occur in a cutaneous form. Most cases of cutaneous diphtheri Read More

Microorganism: the bacterium Corynebacterium diphteriae.

Disease: diphtheria

Occurrence of the disease

Current situation: in Canada, no cases of diphtheria have been reported for some years. In the United States, fewer than 100 cases of diphtheria are recorded annually, and most of the reported cases occur in individuals who have not been vaccinated.

Projections: in theory, it should be possible to completely eradicate this disease, as humans are the only host.

Mechanism of action of the microorganism: the bacteria enter the respiratory system and excrete a toxin that causes tiny membranes to form in the throat. Diphtheria toxin may also enter the blood and result in the destruction of heart, kidney, and nervous tissue.

Symptoms of the disease: diphtheria affects the throat, usually causing pharyngitis or laryngitis. Other symptoms include high fever, nasal discharge containing pus, and weakness.

Diphtheria may also occur in a cutaneous form. Most cases of cutaneous diphtheria occur in tropical regions in individuals who are older than 30 years and have a weakened immune system.

Incubation period: two to five days.

Contagious period: as long as there are lesions: usually two weeks, but in rare cases, more than four weeks.

Hosts: humans.

Transmission: direct contact with airborne droplets. The disease is highly contagious and has a mortality rate of five to ten per cent.

Discoverers of the microorganism: Klebs and Loeffler in 1883-1884.

Treatment of the disease: initially, diphtheria antitoxin, which destroys diphtheria toxin. This is followed by treatment of the infection with antibiotics such as penicillin or erythromycin.

Geographical distribution of the microorganism: worldwide.

Prevention: In all cases, the diphtheria vaccine is combined with other vaccines (the "D" in the name of the vaccine stands for "diphtheria"). Several injections are necessary in order to ensure that the immune system continues to recognize the diphtheria bacterium (vaccination with DTP-Polio-Hib vaccine at two, four, six, and 18 months old, DTP-Polio vaccine at four and six years and d2T5 vaccine at 14-15 years and at ten-year intervals thereafter).

Vaccine: the vaccine contains attenuated diphtheria toxin (diphtheria anatoxin) and is more than 90% effective.

Side effects of the vaccine: sixty per cent of children experience some pain at the site of injection, and 50% experience fever within 48 hours of the injection.


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

Corynebacterium diphteriae

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Microorganism: the bacterium that causes gonorrhea is Neisseria gonorrheae.

Disease: gonorrhea (drawing of a little man having difficulty urinating.) (see Health Canada Information (ask the Museum what are “info Santé Canada”). In medical language, the term blennorrhagia is used.

History: since 1970, following an awareness campaign, the rate of gonorrhea infection dropped sharply in nearly all western countries, including Canada.

Current situation: gonorrhea is the second most important STD of bacterial origin in Canada. In 1998, 5,060 cases of gonorrhea were reported. This disease is now 14 times less important than it was in 1980.

Forecast: while the number of cases of gonorrhea is decreasing, the number of antibiotic-resistant strains is increasing each year. The Canadian objective in the fight against gonorrhea is to eliminate transmission locally by the year 2010.

Mechanism of action of the microorganism: after the microorganisms have entered the body through sexual contact, they att Read More

Microorganism: the bacterium that causes gonorrhea is Neisseria gonorrheae.

Disease: gonorrhea (drawing of a little man having difficulty urinating.) (see Health Canada Information (ask the Museum what are “info Santé Canada”). In medical language, the term blennorrhagia is used.

History: since 1970, following an awareness campaign, the rate of gonorrhea infection dropped sharply in nearly all western countries, including Canada.

Current situation: gonorrhea is the second most important STD of bacterial origin in Canada. In 1998, 5,060 cases of gonorrhea were reported. This disease is now 14 times less important than it was in 1980.

Forecast: while the number of cases of gonorrhea is decreasing, the number of antibiotic-resistant strains is increasing each year. The Canadian objective in the fight against gonorrhea is to eliminate transmission locally by the year 2010.

Mechanism of action of the microorganism: after the microorganisms have entered the body through sexual contact, they attach themselves to the internal wall of the urinary tract or the vagina through hair-like appendages called pili. This attachment prevents the bacteria from being evacuated outside the body by the flow of urine or the normal vaginal discharges. The cells of the immune system then come to attack and eat the bacteria.

Symptoms of the disease: many affected individuals show no symptoms. People who do have symptoms can experience a burning sensation on urinating (this is why the disease is commonly known as “chaude-pisse,” meaning “hot piss” in French), and discharge from the genitals; women can also experience spotting after intercourse. A gonorrhea infection can cause infertility in women. An infected woman can transmit the infection to her child during childbirth. This can cause an infection in the eyelid, i.e., conjunctivitis. Furthermore, the child may become blind. This is why doctors put medication in babies’ eyes when they are born. These are antibiotics such as tetracycline or erythromycin.

Hosts: humans

Incubation period: two to seven days

Contagious period: the contagious period can last several months when the disease is left untreated. Appropriate treatment eliminates contagion in a few hours.

Transmission: this disease is mainly transmitted by contact with the genitals, anus, or mouth of a person who has the disease. During childbirth, a mother who has gonorrhea can transmit it to her child.

Discoverer of the microorganism: Neisser in 1879

Treatment: certain antibiotics such as penicillin or tetracycline. Sexual relations must be avoided during treatment.

Geographical distribution of the microorganism: this disease can be found worldwide. However, in the last twenty years, following awareness campaigns, an important decrease of the disease has been noted in industrialized countries.

Prevention: use of a latex condom

Vaccine: not available


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

Neisseria gonorrhoeae

Dennis Kunkel Microscopy, Inc.

© Dennis Kunkel Microscopy, Inc.


Microorganism: the bacterium Escherichia coli, strain 0157:H7.

Disease: hamburger disease

Occurrence of the disease

History: the 0157: H7 strain of E. coli was isolated from patients suffering from hemorrhagic colitis (bloody diarrhea) during an epidemic in the United States in 1982.

Current situation: in 1998, Quebec and Ontario were the two provinces reporting the greatest number of cases of drinking water contamination by verotoxigenic E. coli and of hamburger disease - 378 cases were reported in Quebec alone. In May and June of 2000, 2,000 people became sick and 21 people died when this strain of E. coli contaminated the water supply of Walkerton, Ontario.

Mechanism of action of the microorganism: in the intestine, the bacteria produce a toxic substance that causes diarrhea.

Symptoms of the disease: in serious cases, bloody diarrhea.

Incubation period: two to eight days.

Contagious period: o Read More

Microorganism: the bacterium Escherichia coli, strain 0157:H7.

Disease: hamburger disease

Occurrence of the disease

History: the 0157: H7 strain of E. coli was isolated from patients suffering from hemorrhagic colitis (bloody diarrhea) during an epidemic in the United States in 1982.

Current situation: in 1998, Quebec and Ontario were the two provinces reporting the greatest number of cases of drinking water contamination by verotoxigenic E. coli and of hamburger disease - 378 cases were reported in Quebec alone. In May and June of 2000, 2,000 people became sick and 21 people died when this strain of E. coli contaminated the water supply of Walkerton, Ontario.

Mechanism of action of the microorganism: in the intestine, the bacteria produce a toxic substance that causes diarrhea.

Symptoms of the disease: in serious cases, bloody diarrhea.

Incubation period: two to eight days.

Contagious period: one to three weeks.

Hosts: cattle are the largest host population, although humans can also act as hosts in some cases. There is some evidence that North American deer are also hosts.

Transmission: primarily by ingestion of contaminated food, especially incompletely cooked minced beef. Transmission may also be by oral-fecal contact.

Treatment: rehydration. Antibacterial agents are of little use and recent studies have shown that their use may even be harmful in some cases.

Geographical distribution of the microorganism: North America, southern South America, Europe, Japan, and Australia.

Prevention: complete cooking of minced meat; regular hand washing.

Vaccine: none.


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

Escherichia coli

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.

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