In Depth Study Material STI.docx

**1. Introduction to STIs** Sexually transmitted infections (STIs) are infections passed from one person to another through sexual contact. The most common STIs discussed in this lecture include: - Gonorrhea - Chlamydia - Syphilis - Herpes Simplex Virus (HSV) - Genital Warts (caused...

**1. Introduction to STIs** Sexually transmitted infections (STIs) are infections passed from one person to another through sexual contact. The most common STIs discussed in this lecture include: - Gonorrhea - Chlamydia - Syphilis - Herpes Simplex Virus (HSV) - Genital Warts (caused by Human Papillomavirus or HPV) **2. Gonorrhea** **Causative Agent:** - *Neisseria gonorrhoeae* (also known as \"gonococcus\") is a gram-negative diplococcus with a coffee bean shape. - Fastidious and susceptible to drying, requires enriched medium and CO2 for growth. **Epidemiology:** - Incidence dropped in the 1990s but has been increasing again, especially in young adults (age 20-25). - Transmitted through mucous membrane contact (e.g., sexual contact or perinatally from mother to newborn). **Clinical Manifestations:** - Mucopurulent urethritis (urethral discharge) - Mucopurulent cervicitis (inflammation of the cervix) - Pelvic inflammatory disease (PID) in women - Pharyngitis (sore throat), conjunctivitis, and disseminated gonococcal infections, which may lead to arthritis or joint infections. - Neonatal gonococcal eye infections (ophthalmia neonatorum). **Diagnosis:** - Nucleic acid amplification testing (NAAT), including PCR, is more sensitive than culture as it can detect dead organisms. - Culture of urethral or cervical swabs is still important for detecting antibiotic resistance. **Treatment:** - Cefixime (oral) or ceftriaxone (intramuscular) combined with azithromycin (due to frequent chlamydia co-infection). - Increasing resistance to antibiotics like ciprofloxacin and even to cefixime/ceftriaxone is an emerging issue globally. - Public health contact tracing is critical for limiting the spread. **3. Chlamydia** **Causative Agent:** - *Chlamydia trachomatis* is an obligate intracellular bacterium with no cell wall, meaning it cannot be gram-stained or cultured on artificial media. **Lifecycle:** - Alternates between two forms: - **Reticulate body** (actively replicating form within host cells). - **Elementary body** (inert infectious form transmitted between cells). **Epidemiology:** - One of the most common STIs, primarily affecting those between 15-25 years old. - Asymptomatic carriers are common, especially in women. **Clinical Manifestations:** - **In Men:** Non-gonococcal urethritis (NGU) with mucopurulent discharge. - **In Women:** Cervicitis, PID, and complications like ectopic pregnancy and infertility. - Can cause conjunctivitis in neonates. - Reactive arthritis (formerly known as Reiter\'s syndrome), involving urethritis, conjunctivitis, and arthritis. **Diagnosis:** - NAAT is the primary diagnostic tool. - For men, urine samples are the preferred method, while self-taken vaginal swabs are most sensitive for women. **Treatment:** - Doxycycline or azithromycin. Erythromycin may be used in specific cases. - No beta-lactam antibiotics (e.g., penicillin) are used because chlamydia lacks a cell wall. - Public health contact tracing is required. **4. Syphilis** **Causative Agent:** - *Treponema pallidum*, a spirochete that is too fine to be detected by gram staining and is often visualized using darkfield microscopy. **Epidemiology:** - Prevalence has been increasing since 2000, especially among men with multiple male partners. - Transmitted through sexual contact or transplacentally (from mother to fetus). **Clinical Presentation:** - **Primary Syphilis:** A painless chancre (ulcer) forms at the site of infection. - **Secondary Syphilis:** Systemic symptoms like a rash (that does not spare the palms and soles), flu-like illness, and lymphadenopathy. - **Latent Syphilis:** Asymptomatic phase after secondary syphilis resolves. - **Tertiary Syphilis:** Cardiovascular and neurological complications, including dementia, paralysis, and skin or internal masses (gummas). - **Congenital Syphilis:** Bone, teeth, and brain damage in newborns. **Diagnosis:** - Serology is the mainstay. Non-treponemal tests (RPR, VDRL) detect inflammation and can be used to monitor treatment. Treponemal tests (EIA, TPPA) confirm the diagnosis. - Darkfield microscopy is only used for primary chancres. **Treatment:** - Penicillin is the treatment of choice, with doxycycline as an alternative in case of penicillin allergy. - Monitoring with RPR titres helps track response to treatment. **5. Herpes Simplex Virus (HSV)** **Causative Agent:** - Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). Both types can cause genital or oral lesions. **Epidemiology:** - Common in all populations, with seroprevalence increasing with age and the number of sexual partners. - Neurotropic virus, meaning it invades nerves and becomes dormant. Reactivates during times of stress or immune suppression. **Clinical Presentation:** - Painful genital lesions, fever, headache, malaise, and painful urination. - Recurrent infections are more common with HSV-2, but HSV-1 can also affect the genitals. - Virus shedding can occur without visible lesions. **Diagnosis:** - Clinical diagnosis based on symptoms. - Confirmed with NAAT or PCR of lesion swabs. **Treatment:** - Antiviral medications like acyclovir or valacyclovir. - Prophylaxis may be needed for frequent recurrences. **6. Genital Warts (HPV)** **Causative Agent:** - Human papillomavirus (HPV), with many different serotypes. Some serotypes cause genital warts, while others are linked to cervical, anal, or oral cancers. **Transmission:** - Direct skin-to-skin contact, often during sexual activity. - Infection can be asymptomatic and self-resolve, but certain strains can lead to cancer. **Clinical Presentation:** - Warts may appear on the genitals, perianal region, or remain asymptomatic. **Treatment:** - Removal of warts via chemical means, freezing, or surgical methods. - Vaccination against HPV (especially cancer-causing strains) is available and effective. This study guide provides a consolidated overview of the lecture content on STIs, focusing on key pathogens, their clinical manifestations, diagnostic approaches, and treatments. For further detail on specific areas, such as lifecycle diagrams or advanced diagnostics, you may refer to the lecture slides and transcript provided during the course. 4o **You said:** The course also has practice quizzes per lecture. If I paste the questions for this lecture, will you have an idea of what the midterm would be like? And what to focus on? **ChatGPT said:** ChatGPT Yes, I can certainly help with that! If you share the practice quiz questions, I can analyze them and give you insights into what types of questions might appear on the midterm. This will also help identify key concepts to focus on, such as particular pathogens, diagnostic methods, or clinical manifestations that are likely to be emphasized in the exam. Feel free to paste the questions, and I'll assist with study strategies and potential exam topics. 4o **You said:** Question 1 (1 point) The gram stain of urethral discharge of a 32 year old man has \"gram negative diplococci\" seen both within cells and outside \"pus cells\". What infection is this finding most consistent with? Question 1 options: LGV Gonorrhea Syphilis Chlamydia Question 2 (1 point) Which of the following is NOT true of the elementary body of Chlamydia trachomatis? Question 2 options: It actively replicates within cells It is important in transmission It develops into the reticulate body It can infect conjunctival cells Question 3 (1 point) Complications of pelvic inflammatory disease include: Question 3 options: trachoma ectopic pregnancy proctitis epididymitis Question 4 (1 point) Which of the following is true of Treponema pallidum Question 4 options: It requires additional CO2 to grow on chocolate agar it is usually seen with darkfield microscopy it appears as a gram negative spirochaete it is usually detected using nucleic acid amplification Question 5 (1 point) Which of the following is true of genital herpes? Question 5 options: It is caused by a double stranded DNA virus recurrent episodes tend to increase in severity it can only be transmitted when vesicles are visible it is rarely seen in people over 30 years of age Question 6 (1 point) Which of the following statements is NOT true of genital warts Question 6 options: HPV infection can be asymptomatic acyclovir is useful as a treatment agent The incidence has fallen since the introduction of the HPV vaccine some serotypes of HPV are associated with cancer **ChatGPT said:** ChatGPT Based on the quiz questions you\'ve provided, here's an analysis of each question and what it might suggest about what to expect on the midterm, as well as the topics you should focus on: **Question 1: Gram stain of urethral discharge showing gram-negative diplococci** This question is directly testing knowledge of the microbiological characteristics of **Neisseria gonorrhoeae**, the causative agent of **gonorrhea**, which is a gram-negative diplococcus. Since this is a classic finding in gonorrhea, it suggests a focus on: - **Microbial identification** through gram staining, particularly in urethral infections. - Common characteristics of **Neisseria gonorrhoeae** (gram-negative diplococci, fastidious growth). **Answer:** Gonorrhea **Question 2: Elementary body of Chlamydia trachomatis** This question is probing understanding of **Chlamydia\'s life cycle**, specifically the difference between the elementary body and the reticulate body. The elementary body is the **transmissible form**, while the **reticulate body replicates within cells**. This question suggests that you should focus on: - **Chlamydia\'s unique lifecycle** (elementary body vs. reticulate body). - How **Chlamydia trachomatis** affects different body systems (e.g., conjunctival infection). **Answer:** It actively replicates within cells (this is **false**; the reticulate body is the replicating form). **Question 3: Complications of pelvic inflammatory disease (PID)** PID is a complication of **untreated STIs**, particularly **chlamydia** and **gonorrhea**. This question highlights the need to know the **sequelae of untreated STIs**, such as: - **PID** and its consequences like **ectopic pregnancy** and **infertility**. - **Other complications** of STIs like proctitis and epididymitis, but recognizing which complications are associated with PID. **Answer:** Ectopic pregnancy (this is a common complication of PID). **Question 4: Treponema pallidum** This question is focused on the **detection methods for syphilis** and its unique characteristics, especially how **Treponema pallidum** is difficult to culture and requires **specialized microscopy (darkfield)**. For the midterm, expect to focus on: - Characteristics of **spirochetes** like Treponema pallidum. - **Diagnostic methods** (darkfield microscopy, serology, NAAT). **Answer:** It is usually seen with darkfield microscopy. **Question 5: Genital herpes** This question is testing your understanding of the virology and clinical presentation of **herpes simplex virus (HSV)**, particularly its **double-stranded DNA** nature and its **latency and reactivation** characteristics. Focus on: - The **virology of HSV** (double-stranded DNA virus, types 1 and 2). - How HSV **recurs** (recurrences tend to be less severe). **Answer:** It is caused by a double-stranded DNA virus. **Question 6: Genital warts** This question examines your knowledge of **HPV**, the virus responsible for **genital warts**, and the efficacy of the **HPV vaccine** in reducing the incidence of warts and HPV-associated cancers. Focus on: - The role of **HPV** in causing **genital warts and cancer**. - Treatments for **HPV**, especially understanding that **acyclovir** is not used for HPV (it is used for HSV). **Answer:** Acyclovir is useful as a treatment agent (this is **false**; acyclovir treats herpes, not HPV). **Summary of Focus Areas for Midterm Preparation:** 1. **Microbiology Identification and Diagnostics**: - Be familiar with **gram stains** and other microbial identification techniques (e.g., darkfield microscopy for syphilis). - Know diagnostic tests like **NAAT**, **PCR**, and **serology** for different STIs. 2. **Key Pathogen Characteristics**: - Focus on the causative agents of **gonorrhea**, **chlamydia**, **syphilis**, **herpes**, and **HPV**. - Understand the **life cycles** (e.g., elementary vs. reticulate bodies for Chlamydia) and **infection processes** of these organisms. 3. **Clinical Manifestations**: - Recognize the **signs and symptoms** of each STI, such as **urethral discharge**, **cervicitis**, **PID**, **chancre formation**, **herpes lesions**, and **genital warts**. 4. **Complications and Sequelae**: - Focus on **complications** like **PID**, **ectopic pregnancy**, **conjunctivitis**, and the long-term effects of untreated infections (e.g., tertiary syphilis). 5. **Treatment Protocols**: - Know the **standard treatments** for each infection (e.g., penicillin for syphilis, doxycycline for chlamydia). - Be aware of **antibiotic resistance trends**, particularly for **gonorrhea**. By practicing with these quiz questions, you\'re likely covering the major points that will be emphasized on the midterm. These questions suggest a strong focus on **diagnostic tools**, **microbial characteristics**, and **treatment approaches**, with attention to **clinical presentations** and **potential complications** of each STI.