Cutaneous Infections Manifesting in Maculopapular Rashes

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Questions and Answers

Why is streptococcal toxic shock syndrome (STSS) difficult to diagnose compared to staphylococcal toxic shock syndrome?

Streptococcal TSS has different clinical criteria than staphylococcal TSS.

There are no definitive laboratory tests to confirm the diagnosis of streptococcal TSS. (correct)

Streptococcal TSS is caused by a different type of superantigen than staphylococcal TSS.

Streptococcal TSS has a more rapid onset and progression compared to staphylococcal TSS.

Which of the following is NOT a potential complication of untreated syphilis?

Kidney failure (correct)

Damage to the central nervous system

Skin lesions

Vascular damage

What is the primary difference in the mechanism of action between a superantigen and a conventional antigen in activating T cells?

Superantigens activate a larger percentage of T cells compared to conventional antigens. (correct)

Superantigens do not require processing by antigen-presenting cells, unlike conventional antigens.

Superantigens stimulate the production of different cytokines compared to conventional antigens.

Superantigens bind to different regions of the TCR compared to conventional antigens.

Which of the following is NOT a characteristic clinical feature of toxic shock syndrome?

Vomiting Signup and view all the answers

Which of the following tests is used to confirm a positive screening test for syphilis?

Fluorescent Treponemal Antibody Absorption (FTA-ABS) test Signup and view all the answers

What is the antibiotic of choice for the treatment of primary and secondary syphilis?

Benzathine penicillin Signup and view all the answers

What is the Jarisch-Herxheimer reaction?

A temporary worsening of symptoms after initiating antibiotic treatment Signup and view all the answers

Which of the following tests is a non-treponemal test used for screening for syphilis?

Rapid Plasma Reagin (RPR) test Signup and view all the answers

How can the efficacy of antibiotic treatment for syphilis be determined?

By monitoring declining antibody levels in non-treponemal tests Signup and view all the answers

Which of the following statements about infectious mononucleosis is correct?

It is caused by the Epstein-Barr virus (EBV), which infects T lymphocytes. Signup and view all the answers

What percentage of patients with infectious mononucleosis develop a widely scattered maculopapular rash when treated with amoxicillin or ampicillin?

80% Signup and view all the answers

Which of the following statements regarding the epidemiology of infectious mononucleosis is accurate?

EBV is found worldwide, and the disease is usually more severe in young adults. Signup and view all the answers

Which of the following is the most accurate description of the maculopapular rash associated with infectious mononucleosis?

It is faint, widely scattered, and erythematous. Signup and view all the answers

Which of the following statements is true regarding the diagnosis of infectious mononucleosis?

It is often misdiagnosed as streptococcal pharyngitis, leading to unnecessary treatment with antibiotics. Signup and view all the answers

According to the information provided, which of the following steps is recommended to avoid treating infectious mononucleosis with antimicrobial agents?

Perform a throat culture to rule out Streptococcus pyogenes pharyngitis. Signup and view all the answers

Which of the following statements about secondary syphilis is correct?

Clinical manifestations may include malaise, fever, lymphadenopathy, myalgias, and arthralgias, along with a generalized maculopapular rash. Signup and view all the answers

Which of the following statements accurately describes the pathogenesis of secondary syphilis?

T. pallidum enters the bloodstream and disseminates to various organs, including the skin. Signup and view all the answers

Which of the following is true about the relapses of the rash in untreated secondary syphilis?

Relapses occur in approximately 20% of untreated patients. Signup and view all the answers

What is the highest risk group for secondary syphilis based on the information provided?

Sexually active men and women aged 20-45 years. Signup and view all the answers

Which of the following statements accurately describes the histological findings in the primary chancre of syphilis?

It shows endarteritis, periarteritis, and infiltration with macrophages and polymorphonuclear leukocytes (PMNs). Signup and view all the answers

Which of the following statements about the primary chancre in syphilis is correct?

It is a hard, raised edematous ulcer. Signup and view all the answers

What is the main pathology in Rocky Mountain spotted fever (RMSF)?

Increased vascular permeability Signup and view all the answers

How is the diagnosis of RMSF typically confirmed?

Indirect immunofluorescence assay (IFA) on blood samples Signup and view all the answers

What is a common manifestation of advanced RMSF infection?

Elevated liver enzyme levels Signup and view all the answers

Why is treatment with doxycycline recommended for RMSF?

To target the causative organism Signup and view all the answers

What is a key preventive measure recommended for individuals exposed to tick-infested areas?

Inspecting and removing attached ticks promptly Signup and view all the answers

Why is culturing for the organism rarely performed for diagnosing RMSF?

Low sensitivity of culturing methods Signup and view all the answers

Study Notes

Secondary Syphilis

Secondary syphilis develops about 6-8 weeks after the appearance of the primary chancre.
Symptoms include malaise, fever, lymphadenopathy, myalgias, and arthralgias, with a generalized erythematous maculopapular rash over the entire body.
The lesions regress without treatment, but relapses of the rash can occur in 20% of untreated patients.

Diagnosis of Secondary Syphilis

Diagnosis involves a complete history, physical exam, serologic tests, and darkfield microscopy of fluids from lesions.
Two different serologic tests are used: screening tests and confirmatory tests.
Screening test: non-treponemal test that detects the presence of antibodies reactive with cardiolipin (VDRL and RPR tests).
Confirmatory tests: treponemal tests (TPI, FTA-ABS, and MHA-TP).

Treatment and Prevention of Secondary Syphilis

Benzathine penicillin is the antibiotic of choice for treatment of primary and secondary syphilis.
Many treated patients will develop a Jarisch-Herxheimer reaction within 6-12 hours after initial antibiotic treatment.
Non-treponemal tests are helpful to determine the efficacy of the antibiotic treatment with declining antibody levels after successful treatment.

Infectious Mononucleosis

Caused by Epstein-Barr virus (EBV).
Symptoms include regional lymphadenopathy, petechiae on the hard and soft palates (25-60% of patients), and a maculopapular rash (10-15% of patients).
Misdiagnosis can occur as streptococcal pharyngitis, leading to treatment with amoxicillin or ampicillin, which can cause a widely scattered maculopapular rash in 80% of patients.

Epidemiology of Infectious Mononucleosis

Found worldwide, common and relatively mild in children, and more severe in young adults.
Skin rash develops in 10-15% of patients.

Syphilis - Epidemiology/Pathogenesis

Highest incidence in sexually active men and women aged 20-45 years.
T. pallidum penetrates the skin, causing an inflammatory reaction and a hard chancre (raised edematous ulcer).
Histologic examination of the chancre demonstrates endarteritis, periarteritis, and infiltration of the ulcer with macrophages and PMNs.

Secondary Syphilis Pathogenesis

T. pallidum enters the blood, spreading to almost every organ, including the skin.
Immune response causes mucocutaneous lesions with maculopapular lesions on the skin, and condyloma latum.
Lesions contain viable T. pallidum and are highly infectious.

Toxic Shock Syndrome - Pathogenesis

Superantigens stimulate the immune system, causing overactivation and release of cytokines (TNF-α and β, IL-1, IL-2, and IFN-γ).
High levels of cytokines cause fever, hypotension, and rash.
TNF-α and β cause capillary leakage, leading to peripheral pooling of blood and shock.

Toxic Shock Syndrome - Diagnosis

Clinical and laboratory criteria aid in diagnosis.
Centers for Disease Control and Prevention have developed a case definition of characteristic clinical criteria.

RMSF - Pathogenesis

Rickettsia spread via lymphatics to the blood and attach to endothelial cells.
Vascular permeability increases, leading to edema and hypovolemia.
The classic petechial rash of RMSF develops due to hemorrhage of the capillaries.

RMSF - Diagnosis and Treatment

Culturing for the organism is rarely performed.
Indirect immunofluorescence assay (IFA) can be performed on blood samples.
Immunostaining of a biopsy of the rash can also be performed.
PCR is now performed on blood and skin biopsies.
Treatment with doxycycline should be initiated immediately when RMSF is suspected.

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Description

Explore a quiz on cutaneous infections that present with maculopapular rashes. Learn about the characteristics and manifestations of these infections, including details about infectious mononucleosis caused by the Epstein-Barr virus.