Bacterial Skin Infections Practice Questions

Q: Which nerve is thickened in this patient of Hansen disease?

Greater auricular. ***Greater auricular nerve*** - The image shows a **thickened, cord-like structure** indicative of a hypertrophied nerve, characteristic of **Hansen's disease (leprosy)** affecting a peripheral nerve. The location points towards the greater auricular nerve. - The **greater auricular nerve** is a common site for thickening in leprosy due to its superficial course, making it susceptible to the inflammatory response caused by *Mycobacterium leprae*. *Transverse cervical nerve* - While it is a superficial cervical nerve, involvement of the **transverse cervical nerve** in leprosy is less common or prominent for palpation compared to the greater auricular nerve. - Thickening of this nerve might present with sensory changes over the anterior neck, but it is not typically as clearly palpable as the greater auricular nerve in its common course. *Greater occipital nerve* - The **greater occipital nerve** would be located more posteriorly on the scalp and neck, supplying sensation to the posterior scalp. - Its thickening would typically cause pain or sensory changes in the occipital region, which does not align with the visibly thickened nerve shown in the image. *Lesser occipital nerve* - The **lesser occipital nerve** is also located more posteriorly and superiorly in the neck, innervating the skin behind the ear. - While it can be affected in leprosy, its anatomical position and typical presentation of thickening are distinct from the prominent cord visible in the image, which is clearly positioned more anteriorly and inferiorly near the earlobe.

Q: A child presents with the following lesion in the neck folds. The gram stain from the lesion is shown below. Comment on the diagnosis.

Erythrasma. **Erythrasma** - The image shows a **reddish-brown, finely wrinkled lesion** in an intertriginous area (neck folds), consistent with erythrasma. - The gram stain reveals **long, filamentous Gram-positive bacilli**, characteristic of *Corynebacterium minutissimum*, the causative agent of erythrasma. *Impetigo contagiosa* - This typically presents as **honey-colored crusted lesions** or vesicles, often caused by *Staphylococcus aureus* or *Streptococcus pyogenes*. - Gram stain would show **Gram-positive cocci** (clusters for staph, chains for strep), not filamentous bacilli. *Scrofuloderma* - This is a form of **cutaneous tuberculosis**, typically presenting as **nontender subcutaneous nodules** that eventually ulcerate and discharge caseous material. - Diagnosis is confirmed by identifying acid-fast bacilli or histology showing granulomas; the gram stain and lesion appearance are not consistent. *Scrum pox* - This is a **viral skin infection** (often herpes simplex virus) seen in wrestlers, presenting as **vesicular or ulcerative lesions**. - It would not show filamentous Gram-positive bacilli on a bacterial gram stain.

Q: With reference to lepromin test, which one of the following statements is correct?

Lepromin test is strongly positive in tuberculoid leprosy. ***Lepromin test is strongly positive in tuberculoid leprosy*** - In **tuberculoid leprosy**, the immune system mounts a strong cell-mediated response against *Mycobacterium leprae*, leading to a strongly positive lepromin reaction. - A positive lepromin test indicates a good host immune response and is associated with the **paucibacillary** forms of the disease. *It can be used as a diagnostic test* - The lepromin test is not a diagnostic tool for leprosy; it primarily assesses the host's **cell-mediated immunity** to *Mycobacterium leprae* antigens. - Diagnosis of leprosy relies on **clinical signs**, **skin smears** for acid-fast bacilli, and histopathological examination, not the lepromin test. *Its interpretation is done within 24 hours* - The lepromin test interpretation involves two phases: the **Fernandez reaction** (early reaction at 24-48 hours) and the **Mitsuda reaction** (late reaction at 3-4 weeks). - The most significant and commonly referred result, the **Mitsuda reaction**, is read at **3 to 4 weeks** after injection. *It is not affected by BCG vaccine* - The **BCG vaccine**, which is used to prevent tuberculosis, can induce some cross-reactivity and lead to a positive lepromin test in individuals who have received it. - This cross-reactivity can sometimes confound the interpretation of the lepromin test, as both mycobacteria share common antigens.

Q: The characteristic features of inguinal lymph nodes associated with a primary syphilitic lesion of the vulva are

Firm, shotty, painless nodes that do not suppurate. **Firm, shotty, painless nodes that do not suppurate** - Lymphadenopathy in **primary syphilis** typically presents as **firm, bilateral, painless**, and non-suppurative lymph nodes, often described as "shotty." - These nodes are usually discrete and do not tend to mat together or form abscesses, reflecting the inflammatory response to **_Treponema pallidum_**. *Painful, tender nodes which become matted together to form an abscess* - **Painful, matted, and suppurative** lymph nodes are more characteristic of other infections, such as those caused by bacterial pathogens like **_Staphylococcus aureus_** or **_Streptococcus pyogenes_**, or conditions like **lymphogranuloma venereum**. - These features are generally not associated with the indolent inflammatory response seen in primary syphilis. *Non-suppurative tender enlarged nodes* - While the nodes in primary syphilis are **non-suppurative and enlarged**, they are typically **painless**, not tender. - **Tenderness** can suggest a more acute or active inflammatory process, and the absence of pain is a key distinguishing feature of syphilitic lymphadenopathy. *Painful inflamed nodes which undergo necrosis and develop a chronic sinus* - **Necrotic lymph nodes** with **chronic sinus formation** are indicative of severe and chronic infections such as **tuberculosis (scrofula)** or deep fungal infections, or conditions like **cat-scratch disease** in some cases. - These aggressive features are not consistent with the typical presentation of primary syphilis.

Q: Painless genital ulcer is found in which one of the following genital infections?

Granuloma inguinale. ***Granuloma inguinale*** - Presents as a **painless, slowly progressive ulcerative lesion** that bleeds easily. - Caused by *Klebsiella granulomatis*, it starts as a papule and then becomes a **beefy red, granulation tissue-like ulcer**. *Lymphogranuloma venerum* - Initially presents with a **small, painless papule or vesicle** that often goes unnoticed. - The most prominent clinical feature is **regional lymphadenopathy (buboes)**, which can be painful and suppurate. *Chancroid* - Characterized by **painful, deep, irregular ulcers** with ragged undermined borders. - These ulcers are typically **soft** and can be accompanied by painful inguinal lymphadenopathy. *Herpes simplex* - Causes **multiple, painful vesicular lesions** that quickly erode into ulcers. - These lesions often recur and are associated with **burning or itching sensations** before eruption.

Q: A woman presents with heavy foul smelling discharge with sharply demarcated ulcers without induration on the perineum and the labia majora. Inguinal lymphadenopathy is also present. What is the most probable diagnosis?

Chancroid. ***Chancroid*** - The presence of **heavy, foul-smelling discharge** with **sharply demarcated, painful ulcers** that are **not indurated** on the perineum and labia majora, along with **inguinal lymphadenopathy**, is highly characteristic of chancroid, caused by *Haemophilus ducreyi*. - The **lack of induration** and the **painful nature** of the ulcers are key differentiating features from syphilis (painless chancre with induration). - The **tender inguinal lymphadenopathy** can progress to form suppurative buboes, which is pathognomonic for chancroid. *Tuberculosis* - While tuberculosis can cause genital ulcers, they are typically **chronic, painless**, and often associated with systemic symptoms like weight loss and night sweats, which are not described here. - Genital tuberculosis is less likely to present with acute, foul-smelling discharge and sharply demarcated, non-indurated ulcers with prominent lymphadenopathy in this manner. *Trichomoniasis* - Trichomoniasis causes a **frothy, yellowish-green, foul-smelling vaginal discharge** and can lead to **vaginal irritation** and sometimes "strawberry cervix," but it **does not cause discrete ulcers** on the perineum or labia majora. - This is primarily a vaginitis caused by *Trichomonas vaginalis*, not an ulcerative condition. - Inguinal lymphadenopathy is not a feature of trichomoniasis. *Gonorrhoea* - Gonorrhoea usually presents with a **purulent vaginal or cervical discharge**, dysuria, and pelvic pain in women, but it **does not typically cause ulcers** on the perineum or labia. - This is a mucosal infection affecting the endocervix primarily, not causing ulcerative lesions. - While disseminated gonococcal infection can occur, the predominant presenting feature of ulcers points away from gonorrhoea.

Q: A 45-year-old man presents with a 3-month history of progressive, painless ulcerative lesions on his penis and scrotum. He has no systemic symptoms. Laboratory tests show negative HIV, negative VDRL and TPHA, and negative HSV PCR. Biopsy shows pseudoepitheliomatous hyperplasia with plasma cells and macrophages containing intracytoplasmic organisms. What is the most likely diagnosis?

Granuloma inguinale (Donovanosis). ***Granuloma inguinale (Donovanosis)*** - The presence of **painless, progressive ulcerative lesions** on the genitalia, coupled with **pseudoepitheliomatous hyperplasia** and intracellular organisms (Donovan bodies) within macrophages on biopsy, is highly characteristic of Granuloma inguinale. - The negative results for HIV, VDRL/TPHA, and HSV PCR rule out other common causes of genital ulcers, reinforcing this diagnosis. *Lymphogranuloma venereum* - Typically presents with a **transient, painless papule or ulcer**, followed by painful inguinal lymphadenopathy and **bubo formation**. This patient has progressive, painless ulcers without prominent lymphadenopathy. - Histology would show **stellate abscesses** and granulomas with a mixed inflammatory infiltrate, not pseudoepitheliomatous hyperplasia with intracellular organisms. *Tertiary syphilis* - Characterized by **gummas**, which are granulomatous lesions that can ulcerate, but these usually develop years after primary infection and are typically associated with positive VDRL/TPHA tests. - The **negative VDRL and TPHA** in this case effectively rule out active syphilis at any stage. *Squamous cell carcinoma* - While it can present as a progressive ulcerative lesion, **pseudoepitheliomatous hyperplasia** is a reactive process, not true malignancy; the presence of **intracytoplasmic organisms** on biopsy points away from a neoplastic process. - A biopsy for squamous cell carcinoma would show malignant epithelial cells with invasive growth, not macrophages with intracellular bacteria.

Q: A 30-year-old woman is diagnosed with gonorrhea and reports a penicillin allergy (rash). Which alternative treatment regimen is most appropriate?

Spectinomycin 2g IM single dose. ***Spectinomycin 2g IM single dose*** - **Spectinomycin** is a safe and effective alternative for treating uncomplicated gonorrhea in patients with a history of severe penicillin or cephalosporin allergy. - It provides bactericidal activity against *Neisseria gonorrhoeae* and is administered as a **single intramuscular injection**. *Azithromycin 2g orally single dose* - While azithromycin is part of the dual therapy for gonorrhea (with ceftriaxone), using it as a **monotherapy** is not recommended due to increasing rates of resistance. - The CDC no longer recommends 2g azithromycin monotherapy for gonorrhea due to concerns about **macrolide resistance**. *Cefixime 400mg orally single dose* - **Cefixime** is a third-generation cephalosporin, and a penicillin allergy (especially a rash) may indicate a risk of **cross-reactivity** with cephalosporins. - While it's an alternative, it's generally avoided in significant penicillin allergy due to the potential for hypersensitivity reactions [1] and may have **lower efficacy** than ceftriaxone [2]. *Ciprofloxacin 500mg orally single dose* - **Ciprofloxacin** is a fluoroquinolone, and its use for gonorrhea is no longer recommended due to widespread and increasing **quinolone resistance** of *Neisseria gonorrhoeae* [2]. - Treatment with ciprofloxacin is associated with unacceptably high rates of **treatment failure** in many regions.

Q: Which of the following is NOT characteristic of lymphogranuloma venereum proctitis?

Absence of inguinal lymphadenopathy. Absence of inguinal lymphadenopathy - **Lymphogranuloma venereum (LGV)** characteristically causes **inguinal lymphadenopathy** (buboes) due to its systemic nature and potential concurrent genital involvement, even in cases of isolated rectal infection [1]. - While the rectum drains primarily to **internal iliac and sacral lymph nodes**, LGV's systemic spread and inflammatory response typically result in inguinal lymph node involvement, making its absence atypical [1]. *Painful defecation* - **LGV proctitis** commonly causes **painful defecation** and **tenesmus** due to severe inflammation and ulceration of the rectal mucosa [1]. - The inflammatory process affects **nerve endings** in the rectal wall, leading to significant discomfort during bowel movements [1]. *Constipation alternating with diarrhea* - **Rectal inflammation** from LGV disrupts normal bowel function, causing **altered bowel habits** including constipation alternating with diarrhea. - **Rectal strictures** may develop in chronic cases, further contributing to irregular bowel patterns and incomplete evacuation. *Rectal discharge and bleeding* - **LGV proctitis** typically presents with **mucopurulent rectal discharge** due to extensive mucosal inflammation and secondary bacterial infection [1]. - **Rectal bleeding** occurs from **mucosal ulceration** and increased vascular fragility caused by the inflammatory process.

Question 1

Which nerve is thickened in this patient of Hansen disease?

Accepted Answer

Greater auricular

Answer

Transverse cervical nerve

Answer

Greater occipital nerve

Answer

Lesser occipital nerve

Question 2

A child presents with the following lesion in the neck folds. The gram stain from the lesion is shown below. Comment on the diagnosis.

Accepted Answer

Erythrasma

Answer

Impetigo contagiosa

Answer

Scrofuloderma

Answer

Scrum pox

Question 3

Which one of the following statements is correct regarding leprosy?

Accepted Answer

Type 2 Leprosy Reaction is an immune complex mediated syndrome also known as erythema nodosum leprosum

Answer

Nose is the last site of involvement in lepromatous leprosy

Answer

Type 1 Leprosy Reaction is also called erythema nodosum leprosum

Answer

'Lion face' appearance is seen in tuberculoid leprosy

Question 4

With reference to lepromin test, which one of the following statements is correct?

Accepted Answer

Lepromin test is strongly positive in tuberculoid leprosy

Answer

It can be used as a diagnostic test

Answer

Its interpretation is done within 24 hours

Answer

It is not affected by BCG vaccine

Question 5

The characteristic features of inguinal lymph nodes associated with a primary syphilitic lesion of the vulva are

Accepted Answer

Firm, shotty, painless nodes that do not suppurate

Answer

Painful, tender nodes which become matted together to form an abscess

Answer

Non-suppurative tender enlarged nodes

Answer

Painful inflamed nodes which undergo necrosis and develop a chronic sinus

Question 6

Painless genital ulcer is found in which one of the following genital infections?

Accepted Answer

Granuloma inguinale

Answer

Lymphogranuloma venerum

Answer

Chancroid

Answer

Herpes simplex

Question 7

A woman presents with heavy foul smelling discharge with sharply demarcated ulcers without induration on the perineum and the labia majora. Inguinal lymphadenopathy is also present. What is the most probable diagnosis?

Accepted Answer

Chancroid

Answer

Tuberculosis

Answer

Trichomoniasis

Answer

Gonorrhoea

Question 8

A 45-year-old man presents with a 3-month history of progressive, painless ulcerative lesions on his penis and scrotum. He has no systemic symptoms. Laboratory tests show negative HIV, negative VDRL and TPHA, and negative HSV PCR. Biopsy shows pseudoepitheliomatous hyperplasia with plasma cells and macrophages containing intracytoplasmic organisms. What is the most likely diagnosis?

Accepted Answer

Granuloma inguinale (Donovanosis)

Answer

Lymphogranuloma venereum

Answer

Tertiary syphilis

Answer

Squamous cell carcinoma

Question 9

A 30-year-old woman is diagnosed with gonorrhea and reports a penicillin allergy (rash). Which alternative treatment regimen is most appropriate?

Accepted Answer

Spectinomycin 2g IM single dose

Answer

Azithromycin 2g orally single dose

Answer

Cefixime 400mg orally single dose

Answer

Ciprofloxacin 500mg orally single dose

Question 10

Which of the following is NOT characteristic of lymphogranuloma venereum proctitis?

Accepted Answer

Absence of inguinal lymphadenopathy

Answer

Painful defecation

Answer

Constipation alternating with diarrhea

Answer

Rectal discharge and bleeding

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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