Introduction
Chlamydia is a sexually transmitted disease (STD) contracted by having unprotected sex. It is transmitted when a person’s fluids, such as semen and vaginal fluids, are mixed during sexual intercourse, and the bacterium Chlamydia trachomatis is transferred.
This STD can also be transmitted during the process of giving birth, and such is referred to as congenital Chlamydia (Pillay et al. 25). It carries risks related to damage to the female reproductive organs. This entails a woman finding it hard to conceive after the infection due to the permanent damage to the female reproductive system (Pillay et al. 25). The people who are primarily at risk are sexually active people and those born to mothers with Chlamydia infections (Pillay et al. 25). To better understand chlamydia, it is explored below in various topics.
Morphology of the Agent Causing the Disease
Chlamydia, as mentioned above, is caused by the bacterium Chlamydia trachomatis. It is classified based on its unique morphology (Cheok et al. 127). Chlamydia is an obligate, aerobic intracellular organism of eukaryotic cells with a coccoid or dowel shape. Chlamydia is identified as a gram-negative bacterium because it has a cytoplasmic membrane and an outer sheath similar to those of gram-negative bacteria (Cheok et al. 127). However, the bacterium lacks a peptidoglycan cell wall and cannot survive independently without a host. It cannot synthesize its ATP (Cheok et al. 127). Chlamydia is the most common cause of preventable blindness, with over 4 million people diagnosed annually (Cheok et al. 127).
It is essential to understand the bacterium’s morphology and genome, as this will aid in understanding its pathogenic functions. Specifically, the characteristics that permit its survival in the body, its biological abilities, and its pathogenic virulence. They are non-motile, non-flagellated, and have a distinct developmental cycle involving alternating between two forms. These are an elementary body, the infectious form, and a reticulate body, which is a replicative form (Cheok et al. 127). The elementary body is small and round, with a rigid cell wall that helps it survive outside the host cell. The reticulate body is larger, more irregular, and lacks a cell wall, allowing it to replicate within a host cell. These two distinct characteristics explain how the genus develops survival mechanisms in both worlds.
For breakdown, Chlamydia trachomatis has a glycolytic pathway and a connected tricarboxylic acid cycle (Cheok et al. 127). Glycogen, glucose synthesis, and derivatives are crucial in chlamydial metabolism (Cheok et al. 127). The availability of metabolic antecedents and products, such as pyruvate, succinate, glycerol-3-phosphate, and NADH dehydrogenase, and the rest that the bacterium uses for transport to produce energy (Cheok et al. 127). As mentioned above, Chlamydia trachomatis causes disease by invading and replicating within the host cells, particularly the epithelial cells of the reproductive tract and the eyes.
Unlike other bacterial pathogens such as Vibrio cholera and Clostridium difficile, chlamydia does not produce endotoxins or exotoxins that damage the host tissues and cause disease. Instead, chlamydia within the host cells triggers an immunological response that causes inflammation and tissue damage (Cheok et al. 127). In the case of chlamydial reproductive tract infections, the immune response to the bacteria can lead to scarring and damage to the fallopian tubes, thus increasing the risk of ectopic pregnancy and infertility cases.
Reservoir of Infection
Although three pathogen species have been found to infect various mammals, including birds, humans remain the primary reservoir for chlamydia trachomatis. Chlamydia bacteria cannot survive outside the human host because they lack the biosynthetic pathway (Cheok et al., 127). The bacterium multiplies only in human cells by binding to the host cell’s surface and entering the cell through a two-step process.
A protein on the bacterium’s surface, LIPP, is crucial for binding to the human cell. This is aided by a membrane surrounding the human cell, called the plasma membrane, which comprises many distinct molecules: phospholipids (Cheok et al. 127). Membrane proteins also transport materials between the interior of the cell and its surrounding environments and assist in intercellular communication; the bacterium exploits them.
Disease Transmission
Chlamydia trachomatis is classified as a sexually transmitted disease. This classification shows that it is spread mainly through sexual contact with an infected person. When a healthy person comes into contact with an infected person’s bodily fluids, they are likely to contract the disease.
Sexual contact covers three areas: anal, vaginal, and oral sex. The infected semen and vaginal discharge are agents for transmission. Chlamydia from mother to the baby happens when, during the birthing process, the mother’s blood can come into contact with the baby, leading to eye infections and even pneumonia. This makes it critical to screen mothers during pregnancy to mitigate the risk of mother-to-child transmission during childbirth.
Symptoms of the Disease and the Affected Age Group
Affected Age Group
Chlamydia is an STD that is primarily rampant among young people. According to statistics from the Centers for Disease Control, the largest percentage of reported cases is among people ages 15-25 (CDC 3). This is the age group that is the most sexually active. Additionally, in terms of race, chlamydia is more prevalent in the black community as compared to whites (Cheok et al. 127). This necessitates more research indicating the relationship between race and the bacterium.
Clinical Manifestations in Women
Chlamydia is most commonly referred to as a silent disease in women. This is because it is asymptomatic, and the signs in females occur in the late stages of the infection. The incubation period of the disease in women is also unclear. Due to the slow replication cycle of the disease, it is estimated to be several weeks before an infected lady can show any symptoms of the disease.
The bacteria primarily infect the cervix (CDC 3), which leads to symptoms of cervicitis, such as mucopurulent endocervical discharge and easily induced cervical bleeding. It may also cause urethritis, causing symptoms such as pyuria, dysuria, and increased frequency of urination (CDC 3). Other symptoms in women may include pelvic inflammatory disease, which may be asymptomatic or acute, presenting symptoms such as abdominal or pelvic pain. Additionally, cervical motion tenderness or uterine tenderness may occur during physical examination.
Clinical Manifestations in Men
In men, symptoms mainly occur in urethritis, including watery or mucoid urethral discharge with dysuria. Some men also develop epididymitis, accompanied by unilateral testicular pain, swelling, and tenderness. In men, the rectum can be affected, leading to signs of proctitis, which include rectal pain, discharge, and bleeding. When the eye comes into contact with infected genital fluid, it can lead to conjunctivitis (CDC 3).
While chlamydia can also be transmitted via the oral route, no symptoms have been directly linked to chlamydial infection (CDC 3). The signs and symptoms of chlamydia do not have distinct features that can differentiate it from any other infection. Therefore, lab tests must be ordered before making a final diagnosis based on the clinical manifestations.
Affected Organs
Chlamydia infection affects the penis, vagina, cervix, urethra, anus, eye, and throat. It can cause severe and, in some cases, permanent damage to the reproductive system, leading to infertility. Additionally, the chlamydia pathogen may affect the liver, leading to symptoms resembling gallbladder disease. In women, the infection could spread to the uterus, causing damage to the fallopian tubes, leading to pelvic inflammatory disease and, eventually, infertility.
Mechanism of the Disease
The chlamydial mechanism of infection includes three major processes in the cell. This involves attachment of the bacteria to the host cell, invasion of the bacteria, and replication of the bacteria in the cell. Eventually, the cell’s destruction leads to an inflammatory response (Zuck and Hybiske 149). This leads to pelvic inflammatory disease’s most common complication—first, the bacteria attach themselves to the host cell’s surface (Zuck and Hybiske 149). The bacteria use surface proteins to bind to specific receptors on the cells’ surface, allowing them to adhere to the cells and initiate the infection.
During the second stage, the bacteria invade the cell wall, which the host cell internalizes through endocytosis. The bacteria are then enclosed in a membrane-bound compartment within the cell known as an inclusion (Zuck and Hybiske 149). The inclusion protects the bacteria from the host’s immune system, allowing them to replicate and grow.
The third step is where the bacteria replicate. The bacteria within the inclusion undergo a developmental cycle during which they differentiate into distinct forms (Zuck and Hybiske 149). The bacteria first replicate within the inclusion as small non-infectious and metabolically active particles known as elementary bodies, which then transform into larger metabolically inactive particles called reticulate bodies, which can infect new cells. This causes an immunological response cascade leading to an inflammatory reaction, and depending on the affected organ, the symptom becomes evident (Zuck and Hybiske 149). This could include inflammation in the pelvic area, pneumonia if the lungs are affected, and many more.
Role of the Immune System
Chlamydial infection activates both the innate and the adaptive immune responses. The innate immune system detects the presence of the pathogen. It initiates the immune response through the activation of macrophages, dendritic cells, and natural killer cells (Pillay et al. 25). The adaptive immune system produces specific antibodies and T cells that target and eliminate chlamydial bacteria (Pillay et al. 25).
However, Chlamydia trachomatis, the most common species of chlamydia, has evolved several mechanisms to evade the host immune system, such as inhibiting apoptosis, interfering with antigen presentation, and inducing regulatory T cells. This evasion can result in persistent infections, leading to chronic inflammation, tissue damage, and long-term complications such as infertility (Pillay et al. 25). An effective immune response against chlamydia infection requires a coordinated and sustained effort from both the innate and adaptive immune systems.
Conclusion
In conclusion, this paper has explored Chlamydia and Chlamydia trachomatis, its causative bacteria. It has examined the disease through various topics, including the causal agent’s morphology, the infection reservoir, and disease transmission. It has also examined the symptoms of the disease and the affected age group, clinical manifestation in women and men, affected organs, the mechanism of the disease, and the role of the immune system; in this way, chlamydia has been better understood.
Works Cited
CDC. “Sexually Transmitted Disease Surveillance 2020.” Centers for Disease Control and Prevention, 2022.
Cheok, Yi Y., et al. “Chronic Inflammatory Diseases at Secondary Sites Ensuing Urogenital or Pulmonary Chlamydia Infections.” Microorganisms, vol. 8, no. 1, 2020, pp. 126-127.
Pillay, Jennifer, et al. “Screening for Chlamydia and/or Gonorrhea in Primary Health Care: Systematic Reviews on Effectiveness and Patient Preferences.” Systematic Reviews, vol. 10, no. 1, 2021, pp. 28-30.
Zuck, Meghan, and Kevin Hybiske. “The chlamydia trachomatis extrusion exit mechanism is regulated by host abscission proteins.” National Library of Medicine, vol 7. no. 5, 2019, pp. 149-151.
