Bacterial Skin Infections Practice Questions

Q: A patient with multiple sexual exposures is diagnosed with gonorrhea. What is the appropriate treatment?

Ceftriaxone. ***Ceftriaxone*** - **Ceftriaxone** is the **first-line recommended treatment** for uncomplicated gonorrhea according to **CDC and WHO guidelines**. - Administered as a **single intramuscular injection (500 mg IM)**, it provides highly effective coverage against *Neisseria gonorrhoeae* with minimal resistance. - It works by inhibiting bacterial cell wall synthesis, and is the **gold standard therapy** for gonorrhea treatment. - For patients with multiple sexual exposures, empiric treatment for co-infection with *Chlamydia trachomatis* (doxycycline) should also be considered. *Cefixime* - **Cefixime** was previously used as an oral alternative but is **no longer recommended** as first-line therapy due to **increasing resistance** of *N. gonorrhoeae*. - The CDC removed cefixime from recommended regimens due to **inferior efficacy** compared to ceftriaxone and concerns about treatment failures. - While it is an oral cephalosporin, it is **not appropriate first-line therapy** for gonorrhea. *Doxycycline* - **Doxycycline** is commonly used to treat **co-infection with *Chlamydia trachomatis***, which frequently occurs alongside gonorrhea. - The typical regimen is **100 mg twice daily for 7 days** as adjunctive therapy. - However, doxycycline is **not effective as monotherapy for gonorrhea** and should not be used alone to treat *N. gonorrhoeae* infection. *Acyclovir* - **Acyclovir** is an **antiviral medication** used to treat **herpes simplex virus (HSV)** infections. - It works by inhibiting viral DNA replication and has **no activity against bacterial infections** like gonorrhea. - It would be completely ineffective against *Neisseria gonorrhoeae*.

Q: A 60-year-old person who completed treatment for leprosy many years ago now presents with a punched-out, painless ulcer on the sole of his foot. What is the most appropriate management?

Offloading and comprehensive wound care. ***Offloading and comprehensive wound care*** - **Trophic ulcers** (neuropathic ulcers) in post-leprosy patients are caused by **peripheral neuropathy** and loss of protective sensation, making offloading the cornerstone of management. - **Comprehensive wound care** includes proper dressing, moisture control, and regular monitoring, which are essential for healing in the absence of signs of active infection. *Intense debridement and intravenous antibiotics* - **No signs of infection** are mentioned in the stem (no fever, purulent discharge, or cellulitis), making IV antibiotics inappropriate as first-line treatment. - **Intense debridement** may cause further tissue damage in a clean neuropathic ulcer without evidence of necrosis or infection. *Restart MDT* - The patient has **completed leprosy treatment** years ago, indicating no active **Mycobacterium leprae** infection requiring multidrug therapy. - **Trophic ulcers** are a late complication of **peripheral neuropathy** from leprosy, not active disease requiring antimicrobial treatment. *Amputation* - Amputation is reserved as a **last resort** for cases with severe, uncontrolled infection or extensive tissue necrosis. - **Neuropathic ulcers** can often heal with appropriate **conservative management** including offloading and wound care.

Q: A patient presents with loss of sensation along the ulnar nerve path. The histology is shown in the image, and a Lepromin test was performed. What is the expected outcome?

Tuberculoid leprosy with lepromin positive. ***Tuberculoid leprosy with lepromin positive*** - The image shows **epithelioid cell granulomas** with sparse lymphocytes, characteristic of a **strong cell-mediated immune response** seen in tuberculoid leprosy. - Patients with tuberculoid leprosy typically have a **positive lepromin skin test**, indicating a robust CMI response capable of containing the infection. *Borderline leprosy with lepromin positive* - Borderline leprosy exhibits a wider spectrum of histological features, often with a mix of tuberculoid and lepromatous characteristics, and is typically **lepromin variable or weakly positive**. - The significant presence of well-formed granulomas in the image points more strongly towards the tuberculoid pole rather than borderline forms. *Lepromatous leprosy with lepromin positive* - Lepromatous leprosy is characterized by a **weak or absent cell-mediated immune response**, leading to diffuse infiltration of **foamy macrophages (Virchow cells)** packed with abundant *M. leprae*, and the **absence of well-formed granulomas**. - Patients with lepromatous leprosy are typically **lepromin negative** due to their anergic immune state. *Scrofuloderma* - **Scrofuloderma** is a form of **cutaneous tuberculosis** resulting from direct extension of underlying tuberculous lymphadenitis or osteomyelitis to the skin. - While it involves granulomatous inflammation, the clinical context of ulnar nerve involvement and the specific histological appearance of well-formed epithelioid granulomas with sparse bacilli are more indicative of tuberculoid leprosy.

Q: A 25-year-old male presents with a burning sensation during urination and purulent discharge from the penis, which started 5 days ago. He reports unprotected sexual intercourse with a new partner two weeks ago. Examination reveals an erythematous urethral meatus with noticeable purulent discharge. A Gram stain of the discharge reveals intracellular gramnegative diplococci. The patient is otherwise healthy with no known drug allergies. What is the most appropriate treatment for this patient?

Cefixime 400 mg orally once. ***Cefixime 400 mg orally once*** - This patient presents with symptoms and a Gram stain consistent with **gonococcal urethritis** (**intracellular gram-negative diplococci**) [1]. - Oral cefixime is an alternative first-line option for **uncomplicated gonococcal infections** when intramuscular ceftriaxone is not feasible or available [1]. *Metronidazole 500 mg orally twice daily for 7 days* - **Metronidazole** is primarily used to treat **anaerobic bacterial infections** and **parasitic infections** (e.g., trichomoniasis, bacterial vaginosis). - It is not effective against **Neisseria gonorrhoeae**, the causative agent of this patient's condition. *Doxycycline 100 mg orally twice daily for 7 days* - **Doxycycline** is the treatment of choice for **Chlamydia trachomatis infections** and is often co-administered empirically with gonorrhea treatment due to high rates of co-infection [1]. - While it addresses potential chlamydial co-infection, it is not the primary treatment for **gonococcal urethritis** itself. *Ceftriaxone 500 mg intramuscularly* - **Ceftriaxone 500 mg IM (or 1 gram in some guidelines)** is the **preferred first-line treatment for uncomplicated gonococcal infections** due to its high efficacy and single-dose administration [1]. - While an excellent choice, the question asks for the *most appropriate* given the options, and oral cefixime is an acceptable alternative, especially in scenarios where IM injections are impractical.

Q: Kassowitz rule is related to:

Congenital syphilis. ***Congenital syphilis*** - The **Kassowitz rule** specifically describes the high rate of perinatal mortality (abortion, stillbirth, or death shortly after birth) in cases of untreated maternal syphilis, especially during early stages of infection. - It highlights that the risk is highest when the mother acquires syphilis shortly before or during pregnancy, leading to severe fetal disease. *Primary syphilis* - This stage is characterized by a **chancre** at the site of infection and is the initial presentation in the infected individual, not directly related to fetal outcomes. - While primary syphilis in the mother can lead to congenital syphilis, the Kassowitz rule itself describes the outcome of congenital infection, not the primary infection in the mother. *Latent syphilis* - **Latent syphilis** refers to a stage where the infection is present but asymptomatic, potentially for years. - While it can be transmitted vertically and lead to congenital syphilis, the Kassowitz rule specifically quantifies the mortality risk of congenital syphilis, not the mother's latent infection itself. *Secondary syphilis* - This stage involves a systemic rash and other widespread symptoms in the infected individual, appearing weeks to months after the chancre. - Though highly infectious and a significant risk for vertical transmission, the rule focuses on the severe consequences *for the fetus* when congenital syphilis occurs, not the symptoms of secondary syphilis in the mother.

Q: A man presents with a rash on his flank with itching for the past 2 weeks. The patient has tried several over-the-counter medications, including lotrimin and hydrocortisone, without any improvement. In physical examination, the rash is seen on his palms and the sole of one foot, but no oral lesions are found. What is the likely diagnosis?

Secondary syphilis. ***Secondary syphilis*** - The rash presenting on the **palms and soles** is highly characteristic of **secondary syphilis**, which helps differentiate it from many other dermatological conditions. - The lack of improvement with antifungal (Lotrimin) and corticosteroid (hydrocortisone) treatments further supports a diagnosis other than a fungal infection or inflammatory dermatitis. *Tinea corporis* - This fungal infection typically presents as an **annular (ring-shaped) rash** with central clearing and well-demarcated borders, often on the trunk or limbs. - It would likely show some improvement, even if partial, with **Lotrimin (an antifungal medication)**, which is not the case here. *Pityriasis rosea* - This condition is characterized by an initial **"herald patch"** followed by smaller, oval, pinkish-red patches that often align along skin cleavage lines in a **"Christmas tree" pattern** on the trunk. - It typically spares the palms and soles, which are involved in this patient's presentation. *Contact dermatitis* - This is an inflammatory skin reaction due to contact with an allergen or irritant, presenting as **pruritic (itchy) erythematous (red) patches, possibly with vesicles or bullae**, limited to exposed areas. - While hydrocortisone might offer some relief, the presentation on palms and soles without clear exposure and the lack of response to treatment make it less likely.

Q: A 30-year-old man presents with generalized lymphadenopathy, palmar rash, and condylomata lata 2 months after being treated for primary syphilis. VDRL is positive at 1:128. Which of the following best explains the pathogenesis of these manifestations?

Hematogenous dissemination of spirochetes. Hematogenous dissemination of spirochetes - The manifestations described (generalized lymphadenopathy, palmar rash, and condylomata lata) are classic signs of secondary syphilis, which occurs due to widespread dissemination of T. pallidum through the bloodstream [1]. - The persistence of a high-titer VDRL after primary syphilis treatment further supports active infection with systemic involvement [1]. *Treatment failure* - While possible, treatment failure typically presents with persistent primary lesions or symptoms, not necessarily the characteristic widespread rash and lymphadenopathy of secondary syphilis, especially if the primary infection was reportedly 'treated'. - The specific array of symptoms points more definitively to a stage of syphilis where the pathogen has widely disseminated. *Reinfection with T. pallidum* - Reinfection would typically lead to a primary chancre, although atypical presentations can occur [1]. - The described generalized symptoms and high VDRL titer are more consistent with the secondary stage of a continuous infection rather than a new primary infection. *Immune complex deposition* - While immune complex deposition can play a role in some manifestations of syphilis (e.g., glomerulonephritis), it is not the primary mechanism for the widespread mucocutaneous lesions and lymphadenopathy characteristic of secondary syphilis. - The immune response to the disseminated spirochetes, rather than immune complex deposition, is largely responsible for the clinical findings. *Direct invasion of skin by spirochetes* - While spirochetes are present in skin lesions, the generalized nature of the rash and lymphadenopathy indicates a systemic process, which begins with hematogenous spread to various tissues, including the skin, rather than direct invasion being the sole or primary mechanism [1]. - Direct invasion alone wouldn't explain the systemic lymphadenopathy.

Q: A 24-year-old man presents with dysuria and urethral discharge 5 days after unprotected sexual intercourse. Gram stain of the discharge shows intracellular gram-negative diplococci. The patient reports penicillin allergy. Which of the following is the most appropriate empiric treatment?

Spectinomycin 2g IM single dose. ***Spectinomycin 2g IM single dose*** - **Spectinomycin** is an effective alternative treatment for **gonorrhea** in patients with severe **penicillin/cephalosporin allergies** [1], [2]. - It is administered as a **single intramuscular dose**, which is convenient for adherence. *Ciprofloxacin 500 mg orally single dose* - **Ciprofloxacin** is a fluoroquinolone that was previously used for gonorrhea, but **resistance is now widespread**, making it ineffective for empiric treatment [2]. - Current guidelines do not recommend fluoroquinolones for uncomplicated gonococcal infections due to high rates of **antimicrobial resistance** [2]. *Doxycycline 100 mg orally twice daily for 7 days* - **Doxycycline** is the primary treatment for **Chlamydia trachomatis**, not Neisseria gonorrhoeae [2]. - While co-infection is common, doxycycline alone would not adequately treat the **gonococcal infection** confirmed by Gram stain [3]. *Azithromycin 2g orally single dose* - A **2g dose of azithromycin** is sometimes used in specific situations, but it's increasingly associated with **gonococcal resistance**. - Current CDC guidelines recommend **azithromycin 1g** often in combination with ceftriaxone, reserving higher doses for specific cases or as second-line. *Ceftriaxone 250 mg IM single dose* - **Ceftriaxone** is the **first-line recommended treatment** for uncomplicated gonorrhea, but the patient has a reported **penicillin allergy** [2]. - While cross-reactivity between penicillins and cephalosporins is low, in severe allergies, an alternative like **spectinomycin** is preferred [1].

Q: A 25-year-old man presents with painless penile ulcer for 2 weeks. Physical examination reveals a firm, non-tender, clean-based ulcer with rolled edges. Dark-field microscopy of the lesion shows spirochetes. VDRL test is positive at 1:32 dilution. Which of the following is the most appropriate treatment?

Single dose of benzathine penicillin G 2.4 million units IM. ***Single dose of benzathine penicillin G 2.4 million units IM*** - This is the recommended treatment for **primary syphilis**, characterized by a **painless chancre** and **positive dark-field microscopy** and VDRL [1]. - The single dose is effective because primary syphilis is an early stage of the infection [1]. *Azithromycin 1g orally single dose* - This regimen is primarily used for the treatment of **Chlamydia trachomatis** infections. - It is not effective against **Treponema pallidum**, the causative agent of syphilis. *Three weekly doses of benzathine penicillin G 2.4 million units IM* - This multi-dose regimen is indicated for **late latent syphilis** or **syphilis of unknown duration**, not primary syphilis. - While penicillin is the correct drug, the duration of therapy is too long for an early-stage infection. *Doxycycline 100 mg orally twice daily for 14 days* - Doxycycline is an alternative treatment for **early syphilis** (primary, secondary, or early latent) in patients who are allergic to penicillin. - Given that penicillin is not contraindicated here, it is not the primary choice, and treatment with penicillin is more effective. *Ceftriaxone 250 mg IM single dose* - Ceftriaxone is a treatment for **gonorrhea**, not syphilis. - While it has some activity against *Treponema pallidum*, it is not the recommended first-line treatment for syphilis.

Question 1

A patient with multiple sexual exposures is diagnosed with gonorrhea. What is the appropriate treatment?

Accepted Answer

Ceftriaxone

Answer

Acyclovir

Answer

Cefixime

Answer

Doxycycline

Question 2

A 60-year-old person who completed treatment for leprosy many years ago now presents with a punched-out, painless ulcer on the sole of his foot. What is the most appropriate management?

Accepted Answer

Offloading and comprehensive wound care

Answer

Restart MDT

Answer

Amputation

Answer

Intense debridement and intravenous antibiotics

Question 3

A patient presents with loss of sensation along the ulnar nerve path. The histology is shown in the image, and a Lepromin test was performed. What is the expected outcome?

Accepted Answer

Tuberculoid leprosy with lepromin positive

Answer

Borderline leprosy with lepromin positive

Answer

Lepromatous leprosy with lepromin positive

Answer

Scrofuloderma

Question 4

A 25-year-old male presents with a burning sensation during urination and purulent discharge from the penis, which started 5 days ago. He reports unprotected sexual intercourse with a new partner two weeks ago. Examination reveals an erythematous urethral meatus with noticeable purulent discharge. A Gram stain of the discharge reveals intracellular gramnegative diplococci. The patient is otherwise healthy with no known drug allergies. What is the most appropriate treatment for this patient?

Accepted Answer

Cefixime 400 mg orally once

Answer

Metronidazole 500 mg orally twice daily for 7 days

Answer

Doxycycline 100 mg orally twice daily for 7 days

Answer

Ceftriaxone 500 mg intramuscularly

Question 5

Kassowitz rule is related to:

Accepted Answer

Congenital syphilis

Answer

Primary syphilis

Answer

Latent syphilis

Answer

Secondary syphilis

Question 6

A man presents with a rash on his flank with itching for the past 2 weeks. The patient has tried several over-the-counter medications, including lotrimin and hydrocortisone, without any improvement. In physical examination, the rash is seen on his palms and the sole of one foot, but no oral lesions are found. What is the likely diagnosis?

Accepted Answer

Secondary syphilis

Answer

Tinea corporis

Answer

Pityriasis rosea

Answer

Contact dermatitis

Question 7

A 45-year-old man presents with a 2-month history of painless testicular swelling. He reports being treated for syphilis 20 years ago. Examination reveals bilateral, non-tender testicular enlargement. Which of the following is the most likely diagnosis?

Accepted Answer

Gummatous orchitis

Answer

Hydrocele

Answer

Tuberculosis orchitis

Answer

Epididymitis

Answer

Testicular cancer

Question 8

A 30-year-old man presents with generalized lymphadenopathy, palmar rash, and condylomata lata 2 months after being treated for primary syphilis. VDRL is positive at 1:128. Which of the following best explains the pathogenesis of these manifestations?

Accepted Answer

Hematogenous dissemination of spirochetes

Answer

Treatment failure

Answer

Reinfection with T. pallidum

Answer

Immune complex deposition

Answer

Direct invasion of skin by spirochetes

Question 9

A 24-year-old man presents with dysuria and urethral discharge 5 days after unprotected sexual intercourse. Gram stain of the discharge shows intracellular gram-negative diplococci. The patient reports penicillin allergy. Which of the following is the most appropriate empiric treatment?

Accepted Answer

Spectinomycin 2g IM single dose

Answer

Ciprofloxacin 500 mg orally single dose

Answer

Doxycycline 100 mg orally twice daily for 7 days

Answer

Azithromycin 2g orally single dose

Answer

Ceftriaxone 250 mg IM single dose

Question 10

A 25-year-old man presents with painless penile ulcer for 2 weeks. Physical examination reveals a firm, non-tender, clean-based ulcer with rolled edges. Dark-field microscopy of the lesion shows spirochetes. VDRL test is positive at 1:32 dilution. Which of the following is the most appropriate treatment?

Accepted Answer

Single dose of benzathine penicillin G 2.4 million units IM

Answer

Azithromycin 1g orally single dose

Answer

Three weekly doses of benzathine penicillin G 2.4 million units IM

Answer

Doxycycline 100 mg orally twice daily for 14 days

Answer

Ceftriaxone 250 mg IM single dose

Bacterial Skin Infections — MCQs

Bacterial Skin Infections — MCQs

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