Chlamydial Infections

Pathophysiology and Clinical Presentation

Pathophysiology

• Chlamydia Chlamydia Chlamydiae are obligate intracellular gram-negative bacteria. They lack a peptidoglycan layer and are best visualized using Giemsa stain. The family of Chlamydiaceae comprises 3 pathogens that can infect humans: Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pneumoniae. Chlamydia are obligate intracellular bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology.
• Classified as gram-negative bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology but exhibit poor Gram staining Gram staining Bacteriology
• Exist in 2 forms: elementary bodies (metabolically inactive) and reticulate bodies
• Elementary bodies invade the host cell through endocytosis Endocytosis Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. Endosomes play a central role in endocytosis. The Cell: Cell Membrane.
• Inside the cell, elementary bodies convert to metabolically active reticulate bodies.
• Reticulate bodies replicate inside the host cell via fission.
• After replication, reticulate bodies reorganize into elementary bodies and are released from the cell.
• Clusters of replicating reticulate bodies are known as inclusion bodies.
• C. trachomatis has multiple serovars that cause different clinical manifestations.

C. trachomatis infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease

Genital disease (serovars d–k):

• Women:
  • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
  • Urethritis Urethritis Inflammation involving the urethra. Similar to cystitis, clinical symptoms range from vague discomfort to painful urination (dysuria), urethral discharge, or both. Urinary tract infections (UTIs):
    • Painful urination
    • Frequent urination
    • Pyuria Pyuria The presence of white blood cells (leukocytes) in the urine. It is often associated with bacterial infections of the urinary tract. Pyuria without bacteriuria can be caused by tuberculosis, stones, or cancer. Urinary tract infections (UTIs)
  • Vaginitis: abnormal vaginal discharge
  • Cervicitis Cervicitis Inflammation of the uterine cervix. Gonorrhea/salpingitis:
    • Painful sexual intercourse
    • Abdominal pain Abdominal Pain Acute Abdomen
  • Pelvic inflammatory disease Pelvic inflammatory disease Pelvic inflammatory disease (PID) is defined as a polymicrobial infection of the upper female reproductive system. The disease can affect the uterus, fallopian tubes, ovaries, and adjacent structures. Pelvic inflammatory disease is closely linked with sexually transmitted diseases, most commonly caused by Chlamydia trachomatis, Neisseria gonorrhoeae, and Gardnerella vaginalis. Pelvic Inflammatory Disease ( PID PID Pelvic inflammatory disease (PID) is defined as a polymicrobial infection of the upper female reproductive system. The disease can affect the uterus, fallopian tubes, ovaries, and adjacent structures. Pelvic inflammatory disease is closely linked with sexually transmitted diseases, most commonly caused by Chlamydia trachomatis, Neisseria gonorrhoeae, and gardnerella vaginalis. Pelvic Inflammatory Disease):
    • Chronic pelvic pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways
    • Difficulty becoming pregnant
    • Ectopic (tubal) pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care
• Men:
  • Painful or burning sensation when urinating
  • Unusual discharge from the penis Penis The penis is the male organ of copulation and micturition. The organ is composed of a root, body, and glans. The root is attached to the pubic bone by the crura penis. The body consists of the 2 parallel corpora cavernosa and the corpus spongiosum. The glans is ensheathed by the prepuce or foreskin. Penis: Anatomy
  • Testicular pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways or swelling Swelling Inflammation
  • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
  • Epididymitis Epididymitis Epididymitis and orchitis are characterized by acute inflammation of the epididymis and the testicle, respectively, due to viral or bacterial infections. Patients typically present with gradually worsening testicular pain and scrotal swelling along with systemic symptoms such as fever, depending on severity. Epididymitis and Orchitis
  • Proctitis Proctitis Inflammation of the mucous membrane of the rectum, the distal end of the large intestine. Chronic Granulomatous Disease

Infant disease:

• Maternal infection can cause spontaneous abortion Abortion Expulsion of the product of fertilization before completing the term of gestation and without deliberate interference. Spontaneous Abortion and premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis birth.
• Transmission to infants occurs during passage through the birth canal Birth canal Pelvis: Anatomy.
• Conjunctivitis Conjunctivitis Conjunctivitis is a common inflammation of the bulbar and/or palpebral conjunctiva. It can be classified into infectious (mostly viral) and noninfectious conjunctivitis, which includes allergic causes. Patients commonly present with red eyes, increased tearing, burning, foreign body sensation, and photophobia. Conjunctivitis (50% transmission rate in maternal infection):
  • Typically occurs 1 week after birth
  • Purulent, mucopurulent, hemorrhagic inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the conjunctiva Conjunctiva The mucous membrane that covers the posterior surface of the eyelids and the anterior pericorneal surface of the eyeball. Eye: Anatomy
  • Eyelid edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
  • Follicular infiltration of the inner eyelid
  • Occurs in 1 eye and then in the other
  • Mostly inconsequential healing
• Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia:
  • Tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination
  • ↑ Respiratory effort
  • Snorkeling sounds while breathing
  • Refusal of food
  • Cyanosis Cyanosis A bluish or purplish discoloration of the skin and mucous membranes due to an increase in the amount of deoxygenated hemoglobin in the blood or a structural defect in the hemoglobin molecule. Pulmonary Examination in severe cases
• Post-infection complications:
  • More common in young men
  • Follow an STD STD Sexually transmitted diseases (STDs) are infections that spread either by vaginal intercourse, anal sex, or oral sex. Symptoms and signs may include vaginal discharge, penile discharge, dysuria, skin lesions (e.g., warts, ulcers) on or around the genitals, and pelvic pain. Some infections can lead to infertility and chronic debilitating disease. Sexually Transmitted Infections (STIs)
  • Autoimmune in origin
  • Reactive arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis
  • Reactive arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis triad (RAT):
    • Urethritis Urethritis Inflammation involving the urethra. Similar to cystitis, clinical symptoms range from vague discomfort to painful urination (dysuria), urethral discharge, or both. Urinary tract infections (UTIs)
    • Conjunctivitis Conjunctivitis Conjunctivitis is a common inflammation of the bulbar and/or palpebral conjunctiva. It can be classified into infectious (mostly viral) and noninfectious conjunctivitis, which includes allergic causes. Patients commonly present with red eyes, increased tearing, burning, foreign body sensation, and photophobia. Conjunctivitis
    • Arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis

Eye disease (serovars a–c):

• Early stage (active trachoma): 
  • Conjunctivitis Conjunctivitis Conjunctivitis is a common inflammation of the bulbar and/or palpebral conjunctiva. It can be classified into infectious (mostly viral) and noninfectious conjunctivitis, which includes allergic causes. Patients commonly present with red eyes, increased tearing, burning, foreign body sensation, and photophobia. Conjunctivitis
  • Redness Redness Inflammation, light sensitivity Sensitivity Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Blotting Techniques, mucopurulent discharge
• Late stage (cicatrical trachoma):
  • Conjunctival scarring Scarring Inflammation
  • Repeated infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease lead to eyelid scarring Scarring Inflammation, entropion Entropion The turning inward (inversion) of the edge of the eyelid, with the tarsal cartilage turned inward toward the eyeball. Sjögren’s Syndrome, and eventually corneal damage and blindness Blindness The inability to see or the loss or absence of perception of visual stimuli. This condition may be the result of eye diseases; optic nerve diseases; optic chiasm diseases; or brain diseases affecting the visual pathways or occipital lobe. Retinopathy of Prematurity.

Lymphogranuloma venereum (serovars l1–l3):

• Sexually transmitted C. trachomatis infection of the lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy and lymphatics
• Presents with genital ulceration Ulceration Corneal Abrasions, Erosion, and Ulcers and painful swollen lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy in the groin Groin The external junctural region between the lower part of the abdomen and the thigh. Male Genitourinary Examination (often unilateral)
• Can result in rectal inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, or swollen lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy in other parts of the body

Respiratory diseases caused by C. pneumoniae and C. psittaci

• C. pneumoniae infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease are frequently asymptomatic, but can present as:
  • Pharyngitis Pharyngitis Pharyngitis is an inflammation of the back of the throat (pharynx). Pharyngitis is usually caused by an upper respiratory tract infection, which is viral in most cases. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and hoarseness. Pharyngitis
  • Sinusitis Sinusitis Sinusitis refers to inflammation of the mucosal lining of the paranasal sinuses. The condition usually occurs concurrently with inflammation of the nasal mucosa (rhinitis), a condition known as rhinosinusitis. Acute sinusitis is due to an upper respiratory infection caused by a viral, bacterial, or fungal agent. Sinusitis
  • Bronchitis
  • Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia
  • All symptoms of C. psittaci infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease can also occur in C. pneumoniae infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease.
• Acute C. psittaci infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease are more symptomatic:
  • Atypical and interstitial pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia
  • Dry, persistent, nonproductive cough
  • Extrapulmonary manifestations: 
    • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever/ chills Chills The sudden sensation of being cold. It may be accompanied by shivering. Fever
    • Headaches
    • Photophobia Photophobia Abnormal sensitivity to light. This may occur as a manifestation of eye diseases; migraine; subarachnoid hemorrhage; meningitis; and other disorders. Photophobia may also occur in association with depression and other mental disorders. Migraine Headache
    • Myalgia Myalgia Painful sensation in the muscles. Ion Channel Myopathy
    • Hepatosplenomegaly Hepatosplenomegaly Cytomegalovirus: 70% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship
    • Myocarditis Myocarditis Myocarditis is an inflammatory disease of the myocardium, which may occur alone or in association with a systemic process. There are numerous etiologies of myocarditis, but all lead to inflammation and myocyte injury, most often leading to signs and symptoms of heart failure. Myocarditis
    • Encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis
    • Exanthema

Differential Diagnosis

• Gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection (STI) caused by the gram-negative bacteria Neisseria gonorrhoeae (N. gonorrhoeae). Gonorrhea may be asymptomatic but commonly manifests as cervicitis or urethritis with less common presentations such as proctitis, conjunctivitis, or pharyngitis. Gonorrhea: an STD STD Sexually transmitted diseases (STDs) are infections that spread either by vaginal intercourse, anal sex, or oral sex. Symptoms and signs may include vaginal discharge, penile discharge, dysuria, skin lesions (e.g., warts, ulcers) on or around the genitals, and pelvic pain. Some infections can lead to infertility and chronic debilitating disease. Sexually Transmitted Infections (STIs) caused by Neisseria Neisseria Neisseria is a genus of bacteria commonly present on mucosal surfaces. Several species exist, but only 2 are pathogenic to humans: N. gonorrhoeae and N. meningitidis. Neisseria species are non-motile, gram-negative diplococci most commonly isolated on modified Thayer-Martin (MTM) agar. Neisseria gonorrhoeae that presents with cervicitis Cervicitis Inflammation of the uterine cervix. Gonorrhea, urethritis Urethritis Inflammation involving the urethra. Similar to cystitis, clinical symptoms range from vague discomfort to painful urination (dysuria), urethral discharge, or both. Urinary tract infections (UTIs), and proctitis Proctitis Inflammation of the mucous membrane of the rectum, the distal end of the large intestine. Chronic Granulomatous Disease, and frequently coexists with a chlamydial infection.  Gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection (STI) caused by the gram-negative bacteria Neisseria gonorrhoeae (N. gonorrhoeae). Gonorrhea may be asymptomatic but commonly manifests as cervicitis or urethritis with less common presentations such as proctitis, conjunctivitis, or pharyngitis. Gonorrhea can be diagnosed based on nucleic acid amplification Nucleic acid amplification Laboratory techniques that involve the in-vitro synthesis of many copies of DNA or RNA from one original template. Septic Arthritis test or culture. Treatment is with antibiotics.
• Herpes: Genital herpes Genital Herpes Genital herpes infections are common sexually transmitted infections caused by herpes simplex virus (HSV) type 1 or 2. Primary infection often presents with systemic, prodromal symptoms followed by clusters of painful, fluid-filled vesicles on an erythematous base, dysuria, and painful lymphadenopathy. Labial and Genital Herpes infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease are common STIs STIs Sexually transmitted infections (STIs) or sexually transmitted diseases (STDs) are infections that spread either by vaginal intercourse, anal sex, or oral sex. Symptoms and signs may include vaginal discharge, penile discharge, dysuria, skin lesions (e.g., warts, ulcers) on or around the genitals, and pelvic pain. Some infections can lead to infertility and chronic debilitating disease. Sexually Transmitted Infections (STIs) caused by herpes simplex Herpes Simplex A group of acute infections caused by herpes simplex virus type 1 or type 2 that is characterized by the development of one or more small fluid-filled vesicles with a raised erythematous base on the skin or mucous membrane. It occurs as a primary infection or recurs due to a reactivation of a latent infection. Congenital TORCH Infections virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology-1 and -2. Primary infection Primary infection Herpes Simplex Virus 1 and 2 often starts with prodromal symptoms followed by clusters of painful, fluid-filled vesicles Vesicles Female Genitourinary Examination on an erythematous base. Dysuria Dysuria Painful urination. It is often associated with infections of the lower urinary tract. Urinary tract infections (UTIs) and painful lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy are other manifestations. Herpes infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease remain dormant in the neuronal ganglia, which allows for recurrent infections Recurrent infections Common Variable Immunodeficiency (CVID). Treatment is with antiviral Antiviral Antivirals for Hepatitis B therapy.
• Syphilis Syphilis Syphilis is a bacterial infection caused by the spirochete Treponema pallidum pallidum (T. p. pallidum), which is usually spread through sexual contact. Syphilis has 4 clinical stages: primary, secondary, latent, and tertiary. Syphilis: a bacterial infection that usually spreads by sexual contact. Syphilis Syphilis Syphilis is a bacterial infection caused by the spirochete Treponema pallidum pallidum (T. p. pallidum), which is usually spread through sexual contact. Syphilis has 4 clinical stages: primary, secondary, latent, and tertiary. Syphilis begins as a painless sore on the genitals, rectum Rectum The rectum and anal canal are the most terminal parts of the lower GI tract/large intestine that form a functional unit and control defecation. Fecal continence is maintained by several important anatomic structures including rectal folds, anal valves, the sling-like puborectalis muscle, and internal and external anal sphincters. Rectum and Anal Canal: Anatomy, or mouth. The mode of transmission is via the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions or contact of the mucous membranes with sores. The causative organism can remain dormant in the body before reactivating at certain times. Treatment is with penicillin Penicillin Rheumatic Fever injection. If untreated, syphilis Syphilis Syphilis is a bacterial infection caused by the spirochete Treponema pallidum pallidum (T. p. pallidum), which is usually spread through sexual contact. Syphilis has 4 clinical stages: primary, secondary, latent, and tertiary. Syphilis can damage internal organs and lead to fatality.
• Genital warts Warts Benign epidermal proliferations or tumors; some are viral in origin. Female Genitourinary Examination: a manifestation of human papillomavirus Human papillomavirus Human papillomavirus (HPV) is a nonenveloped, circular, double-stranded DNA virus belonging to the Papillomaviridae family. Humans are the only reservoir, and transmission occurs through close skin-to-skin or sexual contact. Human papillomaviruses infect basal epithelial cells and can affect cell-regulatory proteins to result in cell proliferation. Papillomavirus (HPV) ( HPV HPV Human papillomavirus (HPV) is a nonenveloped, circular, double-stranded DNA virus belonging to the Papillomaviridae family. Humans are the only reservoir, and transmission occurs through close skin-to-skin or sexual contact. Human papillomaviruses infect basal epithelial cells and can affect cell-regulatory proteins to result in cell proliferation. Papillomavirus (HPV)) infection, which is common in adolescents and presents with warts Warts Benign epidermal proliferations or tumors; some are viral in origin. Female Genitourinary Examination in the genital area. Diagnosis can be made clinically.  Warts Warts Benign epidermal proliferations or tumors; some are viral in origin. Female Genitourinary Examination can be treated by surgical excision or local ablation. HPV HPV Human papillomavirus (HPV) is a nonenveloped, circular, double-stranded DNA virus belonging to the Papillomaviridae family. Humans are the only reservoir, and transmission occurs through close skin-to-skin or sexual contact. Human papillomaviruses infect basal epithelial cells and can affect cell-regulatory proteins to result in cell proliferation. Papillomavirus (HPV) has been linked to cervical cancer Cervical cancer Cervical cancer, or invasive cervical carcinoma (ICC), is the 3rd most common cancer in women in the world, with > 50% of the cases being fatal. In the United States, ICC is the 13th most common cancer and the cause of < 3% of all cancer deaths due to the slow progression of precursor lesions and, more importantly, effective cancer screening. Cervical Cancer; therefore, prevention is very important.
• Community-acquired pneumonia Community-Acquired Pneumonia Pneumonia in Children: a bacterial or viral infection of the lung parenchyma. Community-acquired pneumonia Community-Acquired Pneumonia Pneumonia in Children can be caused by several organisms and presents with constitutional and respiratory symptoms similar to chlamydial pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia. Diagnosis is usually established using sputum cultures Cultures Klebsiella. Antibiotics are the mainstay of therapy.