Bacillus anthracisBacillus anthracis

R.Varidianto Yudo T., dr.,MKesR.Varidianto Yudo T., dr.,MKes

Lab. MikrobiologiLab. Mikrobiologi Fakultas Kedokteran Universitas Hang Fakultas Kedokteran Universitas Hang

TuahTuah

Gram-positive rods of medical Gram-positive rods of medical importance. importance.

B. anthracisB. anthracis causes anthrax, which is causes anthrax, which is common in animals but rare in common in animals but rare in humans. humans.

Human disease occurs in three main Human disease occurs in three main forms: forms: cutaneous cutaneous pulmonary (inhalation) pulmonary (inhalation) gastrointestinal. gastrointestinal.

Properties Properties

B. anthracisB. anthracis is a large gram-positive rod is a large gram-positive rod with square ends, frequently found in with square ends, frequently found in chains. chains.

Its antiphagocytic capsule is composed of Its antiphagocytic capsule is composed of D-glutamateD-glutamate. (This is unique--capsules of . (This is unique--capsules of other bacteria are polysaccharides.) other bacteria are polysaccharides.)

It is nonmotile, whereas other members of It is nonmotile, whereas other members of the genus are motile. the genus are motile.

Anthrax toxin is encoded on one Anthrax toxin is encoded on one plasmidplasmid and the polyglutamate capsule is encoded and the polyglutamate capsule is encoded on a different plasmid. on a different plasmid.

Transmission Transmission

Spores of the organism persist in soil for Spores of the organism persist in soil for years. years.

Humans are most often infected cutaneously Humans are most often infected cutaneously at the time of trauma to the skin, which at the time of trauma to the skin, which allows the spores on animal products, such allows the spores on animal products, such as hides, bristles, and wool, to enter. as hides, bristles, and wool, to enter.

Spores can also be inhaled into the Spores can also be inhaled into the respiratory tract. respiratory tract.

Pulmonary (inhalation) anthrax occurs when Pulmonary (inhalation) anthrax occurs when spores are inhaled into the lungs. spores are inhaled into the lungs.

Gastrointestinal anthrax occurs when Gastrointestinal anthrax occurs when contaminated meat is ingested. contaminated meat is ingested.

Inhalation anthrax is not communicable from Inhalation anthrax is not communicable from person-to-person, despite the severity of the person-to-person, despite the severity of the infection. infection.

After being inhaled into the lung, the After being inhaled into the lung, the organism moves rapidly to the mediastinal organism moves rapidly to the mediastinal lymph nodes, where it causes hemorrhagic lymph nodes, where it causes hemorrhagic mediastinitis. mediastinitis.

Because it leaves the lung so rapidly, it is not Because it leaves the lung so rapidly, it is not transmitted by the respiratory route to transmitted by the respiratory route to others.others.

Pathogenesis Pathogenesis

Pathogenesis is based primarily on the Pathogenesis is based primarily on the production of two exotoxins, collectively production of two exotoxins, collectively known as anthrax toxin. known as anthrax toxin.

The two exotoxins, The two exotoxins, edema factoredema factor and and lethal factorlethal factor, each consist of two proteins , each consist of two proteins in an A-B subunit configuration. in an A-B subunit configuration.

The The BB, or binding, subunit in each of the , or binding, subunit in each of the two exotoxins is two exotoxins is protective antigenprotective antigen. .

The The AA, or active, subunit has , or active, subunit has enzymatic enzymatic activityactivity. .

Clinical Findings Clinical Findings

The typical lesion of cutaneous anthrax is a The typical lesion of cutaneous anthrax is a painless ulcer with a black eschar (crust, painless ulcer with a black eschar (crust, scab). scab).

Local edema is striking. Local edema is striking. The lesion is called a malignant pustule. The lesion is called a malignant pustule.

Untreated cases progress to bacteremia and Untreated cases progress to bacteremia and death. death.

Pulmonary (inhalation) anthrax, also known as Pulmonary (inhalation) anthrax, also known as "woolsorter's disease," begins with "woolsorter's disease," begins with nonspecific respiratory tract symptoms nonspecific respiratory tract symptoms resembling influenza, especially a dry cough resembling influenza, especially a dry cough and substernal pressure. and substernal pressure.

This rapidly progresses to hemorrhagic This rapidly progresses to hemorrhagic mediastinitis, bloody pleural effusions, mediastinitis, bloody pleural effusions, septic shock, and death. septic shock, and death.

Although the lungs are infected, the Although the lungs are infected, the classic features and x-ray picture of classic features and x-ray picture of pneumonia are not present. pneumonia are not present.

Mediastinal widening seen on chest x-ray Mediastinal widening seen on chest x-ray is an important diagnostic criterion. is an important diagnostic criterion.

Hemorrhagic mediastinitis and Hemorrhagic mediastinitis and hemorrhagic meningitis are severe life-hemorrhagic meningitis are severe life-threatening complications. threatening complications.

The symptoms of gastrointestinal anthrax The symptoms of gastrointestinal anthrax include vomiting, abdominal pain, and include vomiting, abdominal pain, and bloody diarrhea. bloody diarrhea.

Laboratory Diagnosis Laboratory Diagnosis Smears show large, gram-positive rods in Smears show large, gram-positive rods in

chains. chains. Spores are usually not seen in smears of Spores are usually not seen in smears of

exudate because spores form when exudate because spores form when nutrients are insufficient, and nutrients are nutrients are insufficient, and nutrients are plentiful in infected tissue. plentiful in infected tissue.

Nonhemolytic colonies form on blood agar Nonhemolytic colonies form on blood agar aerobically. aerobically.

In case of a bioterror attack, rapid In case of a bioterror attack, rapid diagnosis can be performed in special diagnosis can be performed in special laboratories using polymerase chain laboratories using polymerase chain reaction (PCR)-based assays. reaction (PCR)-based assays.

Another rapid diagnostic procedure is Another rapid diagnostic procedure is the direct fluorescent antibody test the direct fluorescent antibody test that detects antigens of the that detects antigens of the organism in the lesion. organism in the lesion.

Serologic tests, such as an ELISA test Serologic tests, such as an ELISA test for antibodies, require acute and for antibodies, require acute and convalescent serum samples and can convalescent serum samples and can only be used to make a diagnosis only be used to make a diagnosis retrospectively. retrospectively.

Prevention Prevention Ciprofloxacin or doxycycline was used as Ciprofloxacin or doxycycline was used as

prophylaxis in those exposed during the outbreak prophylaxis in those exposed during the outbreak in the United States in 2001. in the United States in 2001.

People at high risk can be immunized with cell-flee People at high risk can be immunized with cell-flee vaccine containing purified protective antigen as vaccine containing purified protective antigen as immunogen. immunogen.

The vaccine is weakly immunogenic, and six doses The vaccine is weakly immunogenic, and six doses of vaccine over an 18-month period are given. of vaccine over an 18-month period are given.

Annual boosters are also given to maintain Annual boosters are also given to maintain protection. protection.

Incinerating animals that die of anthrax, rather Incinerating animals that die of anthrax, rather than burying them, will prevent the soil from than burying them, will prevent the soil from becoming contaminated with spores. becoming contaminated with spores.

Important features of pathogenesis Important features of pathogenesis by Bacillus species. by Bacillus species.