Chlamydial Infections — MCQs
Why does Chlamydia trachomatis infection often remain asymptomatic in women?
Which of the following specimens is most appropriate for Chlamydia trachomatis NAAT testing in men?
Inclusion body containing glycogen is seen in which of the following organisms?
Which one of the following statements best characterizes lympho-granuloma venereum (LGV)?
Which of the following is NOT a complication of untreated trichomoniasis?
Which of the following statements about lymphogranuloma venereum (LGV) is NOT true?
All statements are true about trachoma except:
What is the most sensitive test for Chlamydia in asymptomatic carriers?
A sex worker presents with a genital ulcer and gram-negative diplococci. What is the most likely diagnosis?
Incubation period of LGV:
Chlamydial Infections Indian Medical PG Practice Questions and MCQs
Question 1: Why does Chlamydia trachomatis infection often remain asymptomatic in women?
- A. Due to rapid clearance of organisms
- B. Due to infection of columnar epithelium in endocervix (Correct Answer)
- C. Due to inhibition of inflammatory response
- D. Due to hormonal influence on epithelial cells
Explanation: ***Due to infection of columnar epithelium in endocervix*** - Chlamydia trachomatis primarily infects the **columnar epithelial cells** of the endocervix. - These cells often do not elicit a significant **inflammatory response** or nerve stimulation, leading to a lack of noticeable symptoms. *Due to rapid clearance of organisms* - **Chlamydia infections** are not typically cleared rapidly; they can persist for months or even years if untreated. - The persistence of the organism, even in the absence of symptoms, is what makes it a common cause of **pelvic inflammatory disease (PID)** and infertility. *Due to inhibition of inflammatory response* - While Chlamydia does not always trigger a robust symptomatic inflammatory response in the early stages, it does not actively **inhibit** the immune system's general ability to respond. - Chronic or ascending infections eventually lead to **inflammation** and tissue damage, often resulting in silent but progressive pathology. *Due to hormonal influence on epithelial cells* - While **hormonal changes** can influence the susceptibility of epithelial cells to certain infections, they are not the primary reason for the asymptomatic nature of Chlamydia in women. - The main factor is the **type of cells** infected and the initial lack of a strong symptomatic host response.
Question 2: Which of the following specimens is most appropriate for Chlamydia trachomatis NAAT testing in men?
- A. Blood sample
- B. Prostatic massage fluid
- C. Mid-stream urine
- D. First-void urine (Correct Answer)
Explanation: ***First-void urine*** - **First-void urine** (the initial 10-20 mL of urine) is the **most appropriate specimen** for NAAT testing for *Chlamydia trachomatis* in men because it contains the highest concentration of **urethral epithelial cells and organisms** from the urethra. - This method is also **non-invasive** and **cost-effective**, making it suitable for screening and diagnosis. *Blood sample* - **Blood samples** are not suitable for detecting *Chlamydia trachomatis* at the site of infection (genital tract). - While **serological tests** on blood can detect antibodies, they indicate past exposure rather than current infection and are not used for routine diagnostic screening. *Prostatic massage fluid* - **Prostatic massage fluid** is more typically used to diagnose **prostatitis** or other infections within the prostate gland itself. - It is not the preferred or most sensitive specimen for routine **urethral *Chlamydia trachomatis*** detection. *Mid-stream urine* - **Mid-stream urine** primarily reflects infections in the **bladder** or **kidneys**. - It is unlikely to contain sufficient numbers of **chlamydial organisms** from the urethra to provide an accurate NAAT result compared to first-void urine.
Question 3: Inclusion body containing glycogen is seen in which of the following organisms?
- A. Chlamydia trachomatis (Correct Answer)
- B. Chlamydia pneumoniae
- C. Chlamydia psittaci
- D. None of the options
Explanation: ***Chlamydia trachomatis*** - This species is known to form **intracytoplasmic inclusion bodies** that contain **glycogen**. - The presence of this glycogen allows these inclusions to be stained by **iodine**, aiding in laboratory identification. *Chlamydia pneumoniae* - Inclusion bodies of *Chlamydia pneumoniae* are typically **round or pear-shaped** and **do not contain glycogen**. - They are often **vacuolated** and stain poorly with iodine, unlike those of *C. trachomatis*. *Chlamydia psittaci* - The inclusion bodies of *Chlamydia psittaci* are usually **dense and pleiomorphic**, but they **do not contain glycogen**. - They tend to be **larger** and are often found near the host cell nucleus. *None of the options* - This option is incorrect because *Chlamydia trachomatis* specifically forms **glycogen-containing inclusion bodies**. - The presence of glycogen within inclusions is a key distinguishing feature of this species.
Question 4: Which one of the following statements best characterizes lympho-granuloma venereum (LGV)?
- A. It is most common in temperate regions
- B. The causative agent is C. trachomatis (Correct Answer)
- C. In the United States, it is more common among women
- D. Penicillin is effective in early treatment
Explanation: **The causative agent is *C. trachomatis*** - **Lymphogranuloma venereum (LGV)** is a sexually transmitted infection caused by specific serovars (**L1, L2, L2a, L2b, L3**) of *Chlamydia trachomatis*. [1] - These serovars are **invasive** and replicate in **mononuclear phagocytes** of lymphatic tissue, leading to the characteristic lymphadenopathy. [1] *It is most common in temperate regions* - LGV is **most common in tropical and subtropical regions**, particularly in parts of Africa, Southeast Asia, South America, and the Caribbean. - Its prevalence is much lower in temperate regions, though outbreaks can occur, especially in specific *high-risk populations*. *In the United States, it is more common among women* - In developed countries like the United States, LGV primarily affects **men who have sex with men (MSM)**, particularly those who are HIV-positive. [1] - While it can occur in women, its incidence is **significantly lower** in this population. *Penicillin is effective in early treatment* - LGV is caused by *Chlamydia trachomatis*, which is a **bacterium that lacks a peptidoglycan cell wall**, making it inherently resistant to penicillin. - The recommended treatments for LGV are **doxycycline** or **erythromycin**, not penicillin.
Question 5: Which of the following is NOT a complication of untreated trichomoniasis?
- A. Ectopic pregnancy (Correct Answer)
- B. Infertility in women
- C. Preterm delivery
- D. Increased susceptibility to HIV infection
Explanation: ***Ectopic pregnancy*** - While other **sexually transmitted infections (STIs)** like chlamydia and gonorrhea are significant risk factors for **ectopic pregnancy** due to fallopian tube damage, trichomoniasis is not directly associated with it. - The inflammatory response from *Trichomonas vaginalis* primarily affects the **lower genital tract** (vagina, cervix, urethra) and does not typically lead to the kind of **tubal scarring** associated with ectopic gestations. - Unlike ascending infections that cause PID, trichomoniasis remains localized to lower genital structures. *Infertility in women* - Untreated trichomoniasis can lead to **chronic cervicitis** and **endometritis**, which may contribute to female infertility. - The persistent inflammation can affect the **cervical mucus quality** and create a hostile environment for sperm. - Studies have demonstrated associations between *Trichomonas vaginalis* infection and reduced fertility rates. *Preterm delivery* - Studies have linked untreated *Trichomonas vaginalis* infection during pregnancy to an increased risk of **preterm birth** and **low birth weight**. - The inflammation caused by the parasite can contribute to **premature rupture of membranes (PROM)** and uterine contractions. - Maternal trichomoniasis is considered a modifiable risk factor for adverse pregnancy outcomes. *Increased susceptibility to HIV infection* - Trichomoniasis causes **genital inflammation** and microscopic lesions, which can disrupt the natural protective barriers of the genital tract. - These disruptions make individuals more vulnerable to acquiring **HIV infection** if exposed, as the virus can more easily enter the bloodstream through damaged tissues. - Co-infection with trichomoniasis increases HIV viral shedding, further facilitating transmission.
Question 6: Which of the following statements about lymphogranuloma venereum (LGV) is NOT true?
- A. Groove sign is characteristic
- B. Caused by C. trachomatis serovars L1, L2, L3
- C. Can lead to proctocolitis
- D. Primary genital ulcer is painful (Correct Answer)
Explanation: ***Primary genital ulcer is painful*** - The primary genital lesion of LGV, known as a **papule or shallow ulcer**, is typically **painless** and often resolves spontaneously without being noticed [1]. - Painful ulcers are more characteristic of other sexually transmitted infections like **herpes simplex virus (HSV)** or **chancroid** [1]. *Groove sign is characteristic* - The **groove sign**, characterized by enlarged inguinal and femoral lymph nodes separated by the inguinal ligament, is a **pathognomonic clinical feature** of LGV, particularly in later stages [1]. - This sign indicates extensive involvement of regional lymphatics. *Caused by C. trachomatis serovars L1, L2, L3* - LGV is indeed caused by specific **invasive serovars** of *Chlamydia trachomatis*, namely **L1, L2, and L3** [1]. - These serovars have a greater capacity for systemic dissemination and lymphatic tissue invasion compared to the serovars causing ocular or urogenital chlamydial infections. *Can lead to proctocolitis* - **Proctocolitis** (inflammation of the rectum and colon) can occur, especially in individuals engaging in **anal-receptive intercourse**, as the infection can directly involve the rectal mucosa [1]. - This can lead to symptoms such as **rectal pain, discharge, tenesmus, and bleeding** [1].
Question 7: All statements are true about trachoma except:
- A. Strains mainly responsible are A, B, Ba and C
- B. Trachoma is caused by bedsonian organism of psittacosis - lymphogranuloma - trachoma (PLT) group.
- C. Marked papillary hyperplasia with limbal follicles are seen in stage III (Correct Answer)
- D. Corneal ulceration is a complication
Explanation: ***Marked papillary hyperplasia with limbal follicles are seen in stage III*** - This statement is **INCORRECT** and is the exception being sought. - In trachoma staging (MacCallan classification), **Stage III** is characterized by **mature follicles and papillary hypertrophy**, but limbal follicles are not specifically a defining feature of Stage III. - **Limbal follicles** (Herbert's pits when they heal) can occur in trachoma but are not the hallmark of Stage III specifically. - The classic stages focus on conjunctival follicles and papillae, not specifically limbal follicles as a Stage III feature. *Trachoma is caused by bedsonian organism of psittacosis - lymphogranuloma - trachoma (PLT) group* - This statement is **TRUE**. Trachoma is caused by *Chlamydia trachomatis*, which historically was classified as a Bedsonian organism. - The PLT group (Psittacosis-Lymphogranuloma venereum-Trachoma) was an early classification for obligate intracellular bacteria including Chlamydia species. *Strains mainly responsible are A, B, Ba and C* - This statement is **TRUE**. Trachoma is caused by serovars A, B, Ba, and C of *Chlamydia trachomatis*. - These serovars are distinct from those causing other chlamydial infections (D-K for urogenital infections, L1-L3 for lymphogranuloma venereum). *Corneal ulceration is a complication* - This statement is **TRUE**. Corneal ulceration can occur as a complication of trachoma. - Chronic inflammation, scarring, entropion, and trichiasis lead to corneal abrasion and potential ulceration in severe cases.
Question 8: What is the most sensitive test for Chlamydia in asymptomatic carriers?
- A. Tissue culture
- B. Serology
- C. Direct fluorescent antibody test (DFA)
- D. NAAT (Nucleic Acid Amplification Test) (Correct Answer)
Explanation: ***NAAT (Nucleic Acid Amplification Test)*** - **NAATs** detect **Chlamydia trachomatis DNA or RNA**, making them highly sensitive and specific for diagnosing chlamydial infections, especially in asymptomatic individuals. - They can be performed on easily obtained samples like **urine** or **vaginal swabs**, making them ideal for screening. *Tissue culture* - While historically considered the gold standard, **tissue culture** is labor-intensive, expensive, and less sensitive than NAATs. - Its sensitivity is significantly reduced in asymptomatic carriers due to lower bacterial loads. *Serology* - **Serology** detects antibodies to Chlamydia, which indicates past exposure rather than current infection. - It is not useful for diagnosing acute or asymptomatic infections. *Direct fluorescent antibody test (DFA)* - **DFA** involves staining a sample with fluorescent antibodies to directly visualize Chlamydia organisms. - It has lower sensitivity and specificity compared to NAATs, especially in asymptomatic individuals with fewer organisms.
Question 9: A sex worker presents with a genital ulcer and gram-negative diplococci. What is the most likely diagnosis?
- A. H. ducreyi
- B. N. gonorrhoeae (Correct Answer)
- C. C. trachomatis
- D. T. pallidum
Explanation: N. gonorrhoeae - The presence of **gram-negative diplococci** from a genital ulcer is highly characteristic of *Neisseria gonorrhoeae* infection [1]. - While more commonly associated with urethritis [1] or cervicitis, *N. gonorrhoeae* can also present with **genital ulcers**, particularly if there is co-infection or atypical presentation. *H. ducreyi* - *Haemophilus ducreyi* causes **chancroid**, which presents with **painful genital ulcers** and often tender inguinal lymphadenopathy. - However, *H. ducreyi* is a **gram-negative coccobacillus**, not a diplococcus, and typically forms "school of fish" arrangements on Gram stain. *C. trachomatis* - *Chlamydia trachomatis* can cause **genital ulcers** (e.g., lymphogranuloma venereum serovars L1-L3), but it is an **obligate intracellular bacterium** and cannot be visualized on Gram stain as diplococci [1]. - Gram staining for *Chlamydia* would not show distinct bacterial morphology [1]. *T. pallidum* - *Treponema pallidum* causes **syphilis**, which presents with a **painless chancre** (genital ulcer) in its primary stage. - *Treponema pallidum* is a **spirochete** and is too thin to be seen on Gram stain; it is typically identified via **dark-field microscopy** or serological tests.
Question 10: Incubation period of LGV:
- A. 15-45 days
- B. 6 months
- C. 1 month (Correct Answer)
- D. 3-12 days
Explanation: ***1 month*** - The incubation period for the primary lesion (a small, painless papule or vesicle) in **lymphogranuloma venereum (LGV)** is typically **1-4 weeks**, with 1 month being a common estimate [1]. - This primary lesion often goes unnoticed as it heals rapidly, usually within a few days [1]. *15-45 days* - While technically encompassing the range, **15-45 days** might be seen as slightly broad or less precise than the more common "1 month" estimate for the primary lesion. - The more prominent secondary stage with lymphadenopathy typically develops a few weeks after the primary lesion [1]. *6 months* - An incubation period of **6 months** is far too long for LGV. The disease characteristics usually manifest within weeks. - Such a long incubation period would suggest a different type of infection or a very delayed presentation, which is not characteristic of typical LGV. *3-12 days* - An incubation period of **3-12 days** is too short for LGV. This timeframe is more typical for diseases like **genital herpes** or **chancroid** [1]. - LGV caused by *Chlamydia trachomatis* serovars L1, L2, or L3, generally has a longer incubation before the primary lesion appears.
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