Chapter 15: Bacillus and Similar Organisms by Joseph DeFinis

Anthrax

josephdefinis7 — 2025-09-29 01:09:43 UTC

Bacillus anthracis is a metropolitan pathogen of clinical labs. It is commonly seen in wild animals such as sheep, goats, horses, and cattle. The decline in cases of anthrax is due to the number of human and animal vaccinations as well as better methods of handling and importing animal products.

Injectional Anthrax

josephdefinis7 — 2025-09-29 01:18:21 UTC

Injectional anthrax is associated with contaminated drugs of abuse - e.g. heroin. It is basically a skin infection, but has symptoms different from a cutaneous infection. Skin around the infection site can appear bruised, the "tell-tale" lesion (i.e. eschar) is not present. This is a severe soft tissue infection that can lead to fast moving tissue dissemination and septic shock.

Inhalation Anthrax

josephdefinis7 — 2025-09-29 01:29:35 UTC

This has been referred to as pulmonary anthrax in the past. Inhalation anthrax occurs when B. anthracis endspores are inhaled. Macrophages from the lungs ingest them, where they navigate to the lymph nodes causing a systemic infection. It presents as a flu-like infection, with symptoms such as fever, chills, fatigue, non-productive cough, nausea, vomiting, etc. This will progress into dyspnea, edema, cyanosis, shock and eventual death. Radiologists will generally see abnormalities in x-rays (pleural effusion, infiltrates, and mediastinal widening). The attached image is a diagram showing how anthrax endospores navigate from the lungs to the lymphatic vessels, causing a systemic infection.

Cutaneous Anthrax

josephdefinis7 — 2025-09-29 01:37:21 UTC

Cutaneous anthrax occurs the most in humans. It is associated to direct contact with animal products. Infection occurs from close contact with an animal, where endospores enter through a break in the skin. The endospores will incubate within the skin for approximately 2-6 days before clinical manifestations arise. Usually, small papules will appear that mature into a ring of vesicles. The ring of vesicles will then turn into a ulceration.

Eschar

josephdefinis7 — 2025-09-29 01:39:58 UTC

Manifestation of ulceration (i.e. a black necrotic lesion known as an eschar).

Gastrointestinal (Ingested) Anthrax

josephdefinis7 — 2025-09-29 01:55:41 UTC

This form of anthrax results from ingesting bacterial endospores and can present in 1 of 2 ways. Oral/oropharyngeal and gastrointestinal. In oral/oropharyngeal, lesions will form on the buccal cavity or on the tongue, tonsils, or pharyngeal mucosa. Symptoms will include sore throat, lymphadenopathy, and edema of the throat or neck and chest. In gastrointestinal, lesions will usually form at the terminal part of the ileum or cecum's mucosa. Symptoms of G.I. anthrax can be non-specific with progression to abdominal pain, nausea, vomiting, anorexia, fever, bloody diarrhea, and hematemesis (vomiting blood). The mortality rate of G.I. anthrax is higher than other mechanisms of transmission due to the high likelihood of developing sepsis - and how nonspecific the initial symptoms are delaying patient's to seek appropriate medical care.

Edema Toxin (ET)

josephdefinis7 — 2025-09-29 02:02:59 UTC

1 of 2 plasmid borne anthrax toxins. Each of these toxins consists of two proteins. ET is responsible for edema.

Lethal Toxin (LT)

josephdefinis7 — 2025-09-29 02:03:17 UTC

1 of 2 plasmid borne anthrax toxins. Each of these toxins consists of two proteins. LT is responsible for death.

Edema Factor (EF)

josephdefinis7 — 2025-09-29 02:03:56 UTC

1 of 2 proteins that makeup Edema Toxin. This is the functional enzyme of ET.

Lethal Factor (LF)

josephdefinis7 — 2025-09-29 02:04:12 UTC

1 of 2 proteins that makeup Lethal Toxin. This is the functional enzyme of LT.

Protective Antigen

josephdefinis7 — 2025-09-29 02:04:31 UTC

The protective antigen (PA) allows the respective functional enzyme from edema factor (EF) or lethal factor (LF) to gain access to the inside of a host cell. So, protective antigen is going to be the second protein that makes up both EF and LF.