Treponema pallidum is a parasitic spirochete or spiral bacterium, primarily known for causing the STI syphilis. It's tricky to identify, existing in human knowledge for hundreds of years before encountering its nemesis in 1943.
The infection ravages populations especially during the Renaissance and 19th century. It's also common during the Word Wars I and II. Discovered in 1905 T. pallidum is only later identified as the cause of syphilis.
This thin, coiled, and highly motile bacterium is characterized by its unique corkscrew shape and movement. It's distinguished from other bacteria by membrane structure and absence of certain biosynthetic pathways.
Treponema pallidum is anaerobic, living in oxygen-free environments. It's microscopic, about 0.1 to 0.2 micrometers in diameter and 6 to 15 micrometers in length. One micrometer is equivalent to 0.001 mm.
Its flexible cell wall is made of peptidoglycan. Peptidoglycan or murein is a macromolecule, a polysaccharide consisting of sugars and amino acids. It forms a mesh-like layer or sacculus.
This surrounds the bacterial cytoplasmic membrane. It also has axial filaments to enable motility, allowing it to move through tissues and mucosa in its typical freewheeling corkscrew manner.
It's classified as a Gram-negative bacterium due to its unique membrane structure. Its membrane also contributes to its artful immune evasion.
The bacterium is transmitted to another human by contact with syphilis sores typically during sexual activity. It dwells in moist environments such as the mucous membranes of genitals, anus, oral cavity and lymph nodes.
A chemotroph and obligate human pathogen, Treponema pallidum gets energy from breakdown of organic compounds. It relies entirely on its human host, lacking the genetic makeup to synthesize essential nutrients.
Nutritionally, T. pallidum has low needs. It doesn't have the biosynthetic pathways for amino acids, nucleotides or many other essential compounds. T. pallidum feeds from surrounding tissue and the host's immune cells.
Its metabolic byproducts include volatile fatty acids and other organic compounds. These are secreted in negligible quantities. due to the bacterium's lack of metabolism.
T. pallidum reproduces asexually by binary fission. This process involves the elongation of the bacterium, followed by the division of the cell into two identical daughter cells.
The replication cycle is comparatively slow, with a doubling time of 30 to 33 hours, considerably longer than most bacteria who double at an amazing 4 - 20 minutes. Slow growth inhibits laboratory cultures of T. pallidum.
As mentioned a notable characteristic of T. pallidum is its ability to evade the immune system. The bacterium displays extensive genetic variability, helping it adapt to different immune responses.
By modifying its surface proteins it remains undetected, making treatment difficult. Laboratory cultivation of this bacterium is challenging. It requires specialized conditions and use of animal models for research.
T. pallidum demonstrates genetic variability and evasion mechanisms allowing it to persist in an immune-activated environment. This contributes to its talent for causing chronic infection.
Antigen variation: By frequently changing its surface antigens, T. pallidum avoids recognition by the host's immune cells.
Immune system modulation: The bacterium can induce immune suppression, allowing it to persist in the host for long periods without being cleared by the immune response.
The pathogenicity of Treponema pallidum begins with entry into the body. This is often through small abrasions or mucous membranes during sexual contact. Once inside, the bacterium travels in the bloodstream, spreading systemic infection through the host.
Clinical Manifestations
Syphilis progresses through several stages: primary, secondary, latent, and tertiary. Each stage manifests with distinct clinical symptoms:
Primary syphilis: Characterized by the presence of a painless ulcer called a chancre, which appears at the site of infection.
Secondary syphilis: Systemic spread leads to rashes, mucous membrane lesions, and flu-like symptoms.
Latent syphilis: An asymptomatic phase where the bacterium remains in a dormant state.
Tertiary syphilis: Damage to multiple organ systems, including the cardiovascular and nervous systems, may occur years later if left untreated.
The capacity of T. pallidum to persist without symptoms for extended periods complicates early diagnosis and treatment.
Facts about Treponema pallidum
Historical Impact: Syphilis is significant in public health and societal perceptions of disease throughout history, often associated with social stigma.
Diagnostic Challenges: Diagnosis often relies on serological tests, as culturing T. pallidum in vitro is challenging, making it one of the few human pathogens to elude simple laboratory study.
Condoms: Protect against transmission of syphilis by preventing contact with a sore; however sores also occur in areas not covered by a condom. Contact with these can transmit the bacterium.
Global Prevalence: Syphilis remains endemic in various parts of the world.
According to 2022 data, in countries with available stats, Malta has the highest rate of syphilis, at 24.4 cases per 100,000. Next is Luxembourg (23.4), Spain (16.6), Ireland (16.6), Lichtenstein (15.3) and Portugal (14.8).
In the United States, reported syphilis cases increase 80% between 2018 and 2022. Case counts soar from from 115,000 in 2018 to more than 207,000 in 2022.
Highly Sensitive: T. pallidum cannot withstand environmental changes; it dies quickly outside the human body, often within minutes.
Zoonotic Concerns: While primarily a human pathogen, similar Treponema species infect various animals.
Penicillin Sensitivity: Since its introduction in 1943, penicillin has proven 98% effective against T. pallidum, making it the common treatment for syphilis.
Non-Fiction Books:
Fiction Books:
READ: Lora Ley Adventures - Germanic Mythology Fiction Series
READ: Reiker For Hire - Victorian Detective Murder Mysteries