Adult immunization recommendations US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Adult immunization recommendations. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Adult immunization recommendations US Medical PG Question 1: A 29-year-old man comes to the physician for a routine health maintenance examination. He feels well. He works as a nurse at a local hospital in the city. Three days ago, he had a needlestick injury from a patient whose serology is positive for hepatitis B. He completed the 3-dose regimen of the hepatitis B vaccine 2 years ago. His other immunizations are up-to-date. He appears healthy. Physical examination shows no abnormalities. He is concerned about his risk of being infected with hepatitis B following his needlestick injury. Serum studies show negative results for hepatitis B surface antigen, hepatitis B surface antibody, and hepatitis C antibody. Which of the following is the most appropriate next step in management?
- A. Revaccinate with 3-dose regimen of hepatitis B vaccine
- B. Revaccinate with two doses of hepatitis B vaccine
- C. Administer hepatitis B immunoglobulin
- D. Administer hepatitis B immunoglobulin and 3-dose regimen of hepatitis B vaccine (Correct Answer)
- E. Administer hepatitis B immunoglobulin and single dose hepatitis B vaccine
Adult immunization recommendations Explanation: ***Administer hepatitis B immunoglobulin and 3-dose regimen of hepatitis B vaccine***
- This patient had prior vaccination but current serology shows **negative HBsAb**, indicating **non-response** to the vaccine (failure to develop protective antibodies).
- Given exposure to a hepatitis B positive patient, immediate post-exposure prophylaxis with **HBIG** is crucial for passive immunity and immediate protection.
- A **complete 3-dose revaccination series** should be initiated simultaneously, as per **CDC/ACIP guidelines** for vaccine non-responders with occupational exposure [1].
- This provides both immediate passive protection (HBIG) and attempts to establish active immunity through revaccination [1].
*Revaccinate with 3-dose regimen of hepatitis B vaccine*
- While revaccination is necessary due to the non-response, starting a 3-dose regimen alone without **HBIG** would leave the patient vulnerable during the initial period before vaccine response develops.
- After high-risk exposure in a non-responder, both passive (HBIG) and active (vaccine) immunity are required.
*Revaccinate with two doses of hepatitis B vaccine*
- A 2-dose regimen is insufficient; the standard revaccination schedule for non-responders is **3 doses** at 0, 1, and 6 months [1].
- Additionally, this option lacks **HBIG** for immediate protection after the high-risk exposure.
*Administer hepatitis B immunoglobulin*
- **HBIG** alone provides immediate passive immunity, which is crucial given the recent exposure and the patient's non-immune status.
- However, offering only HBIG without initiating active immunization (vaccine series) would leave the patient unprotected once the passive immunity wanes (approximately 3-6 months).
- This approach fails to address the need for long-term protection through revaccination.
*Administer hepatitis B immunoglobulin and single dose hepatitis B vaccine*
- While HBIG is appropriate for immediate protection, giving only a **single dose** of vaccine is inadequate.
- Standard post-exposure management for vaccine non-responders requires initiating a **complete 3-dose revaccination series**, not just one dose [1].
- A single dose would not provide adequate long-term protection for this non-responder.
Adult immunization recommendations US Medical PG Question 2: A 40-year-old pregnant woman, G4 P3, visits your office at week 30 of gestation. She is very excited about her pregnancy and wants to be the healthiest she can be in preparation for labor and for her baby. What vaccination should she receive at this visit?
- A. Measles, mumps, and rubella (MMR)
- B. Varicella vaccine
- C. Herpes zoster vaccine
- D. Live attenuated influenza vaccine
- E. Tetanus, diphtheria, and acellular pertussis (Tdap) (Correct Answer)
Adult immunization recommendations Explanation: ***Tetanus, diphtheria, and acellular pertussis (Tdap)***
- The Tdap vaccine is recommended during each pregnancy, preferably between **27 and 36 weeks of gestation**, to maximize maternal antibody response and passive antibody transfer to the fetus.
- This provides critical protection against **pertussis (whooping cough)** for the newborn, who is too young to be vaccinated.
*Measles, mumps, and rubella (MMR)*
- The **MMR vaccine is a live vaccine** and is **contraindicated during pregnancy** due to the theoretical risk of congenital rubella syndrome, although no cases have been reported.
- It should be administered **postpartum** if the mother is not immune to rubella.
*Varicella vaccine*
- The **varicella vaccine is a live vaccine** and is **contraindicated during pregnancy** due to the theoretical risk of congenital varicella syndrome.
- Like MMR, it should be offered in the **postpartum period** if the woman is not immune.
*Herpes zoster vaccine*
- The herpes zoster vaccine is typically recommended for **older adults** (50 years and older) for shingles prevention.
- It is **not routinely recommended during pregnancy**, and its safety and efficacy in this population have not been sufficiently established.
*Live attenuated influenza vaccine*
- The **live attenuated influenza vaccine (LAIV)** is **contraindicated during pregnancy** due to its live virus content.
- Pregnant women should receive the **inactivated influenza vaccine (IIV)**, which is safe and recommended during any trimester.
Adult immunization recommendations US Medical PG Question 3: A 7-year-old African-American boy presents to his physician with fatigue, bone and abdominal pain, and mild jaundice. The pain is dull and remitting, and the patient complains it sometimes migrates from one extremity to another. His mother reports that his jaundice and pain have occurred periodically for the past 5 years. At the time of presentation, his vital signs are as follows: the blood pressure is 80/50 mm Hg, the heart rate is 87/min, the respiratory rate is 17/min, and the temperature is 36.5°C (97.7°F). On physical examination, the patient appears to be pale with mildly icteric sclera and mucous membranes. On auscultation, there is a soft systolic ejection murmur, and palpation reveals hepatosplenomegaly. His musculoskeletal examination shows no abnormalities. Laboratory investigations show the following results:
Complete blood count
Erythrocytes
3.7 x 106/mm3
Hgb
11 g/dL
Total leukocyte count
Neutrophils
Lymphocytes
Eosinophils
Monocytes
Basophils
7,300/mm3
51%
40%
2%
7%
0
Platelet count
151,000/mm3
Chemistry
Total bilirubin
3.1 mg/dL (53 µmol/L)
Direct bilirubin
0.5 mg/dL (8.55 µmol/L)
A peripheral blood smear shows numerous sickle-shaped red blood cells. Among other questions, the patient’s mother asks you how his condition would influence his vaccination schedule. Which of the following statements is true regarding vaccination in this patient?
- A. The patient’s condition does not affect his chances to get any infection; thus, additional vaccinations are not advised.
- B. The patient should not receive meningococcal, pneumococcal, or Haemophilus influenzae vaccines, because they are likely to cause complications or elicit disease in his case.
- C. The patient should receive the pneumococcal polysaccharide vaccine as soon as possible, because he is at higher risk of getting pneumococcal infection than other children.
- D. The patient should receive serogroup B meningococcal vaccination at the age of 10 years. (Correct Answer)
- E. The patient should receive serogroup B meningococcal vaccination as soon as possible, because he is at higher risk of getting meningococcal infection than other children.
Adult immunization recommendations Explanation: ***The patient should receive serogroup B meningococcal vaccination at the age of 10 years.***
- Patients with **sickle cell disease** (SCD) have **functional asplenia**, increasing their risk for invasive meningococcal disease from encapsulated bacteria.
- The **MenACWY vaccine** should be given starting at age 2 months for high-risk children with asplenia, with boosters every 5 years.
- The **MenB vaccine series** is recommended specifically for individuals **10 years and older** with anatomic or functional asplenia, including SCD patients.
- This statement correctly identifies the age-appropriate timing for MenB vaccination according to **ACIP guidelines**.
*The patient should receive serogroup B meningococcal vaccination as soon as possible, because he is at higher risk of getting meningococcal infection than other children.*
- While SCD patients are at increased risk for meningococcal infections, the **MenB vaccine is not recommended before age 10 years**, even in high-risk patients.
- At age 7, this patient should receive **MenACWY** if not already vaccinated, but MenB vaccination should wait until age 10.
- The timing "as soon as possible" is incorrect for MenB vaccine in this 7-year-old patient.
*The patient's condition does not affect his chances to get any infection; thus, additional vaccinations are not advised.*
- This is completely false. **Sickle cell disease causes functional asplenia**, which dramatically increases the risk of overwhelming sepsis from encapsulated organisms (*S. pneumoniae*, *N. meningitidis*, *H. influenzae* type b).
- Additional vaccinations beyond the routine schedule are **essential and life-saving** for SCD patients.
*The patient should not receive meningococcal, pneumococcal, or Haemophilus influenzae vaccines, because they are likely to cause complications or elicit disease in his case.*
- This is dangerously incorrect. These vaccines are **specifically recommended and safe** for patients with SCD.
- Patients with functional asplenia are at **highest risk** for invasive disease from these encapsulated bacteria, making vaccination crucial.
- These vaccines do not cause complications or elicit disease in SCD patients; they are inactivated or subunit vaccines.
*The patient should receive the pneumococcal polysaccharide vaccine as soon as possible, because he is at higher risk of getting pneumococcal infection than other children.*
- While SCD patients are at high risk for pneumococcal infection, the vaccination schedule is specific: **PCV13** in infancy, followed by **PPSV23** at age 2 years and older.
- At age 7, if not previously vaccinated, catch-up vaccination is needed, but "as soon as possible" without specifying the proper sequence (PCV13 first, then PPSV23) and "polysaccharide vaccine" alone is imprecise.
- The correct answer focuses on MenB at age 10, which is the most specific guideline-based recommendation among the options.
Adult immunization recommendations US Medical PG Question 4: A 29-year-old man presents to the primary care clinic in June for post-discharge follow-up. The patient was recently admitted to the hospital after a motor vehicle collision. At that time he arrived at the emergency department unconscious, hypotensive, and tachycardic. Abdominal CT revealed a hemoperitoneum due to a large splenic laceration; he was taken to the operating room for emergency splenectomy. Since that time he has recovered well without complications. Prior to the accident, he was up-to-date on all of his vaccinations. Which of the following vaccinations should be administered at this time?
- A. Inactivated (intramuscular) influenza vaccine
- B. Live attenuated (intranasal) influenza vaccine
- C. Tetanus booster vaccine
- D. Measles-mumps-rubella vaccine
- E. 13-valent pneumococcal conjugate vaccine (Correct Answer)
Adult immunization recommendations Explanation: ***13-valent pneumococcal conjugate vaccine***
- Patients who have undergone a **splenectomy** are at increased risk for **overwhelming post-splenectomy infection (OPSI)**, particularly from encapsulated bacteria like *Streptococcus pneumoniae*.
- The **13-valent pneumococcal conjugate vaccine (PCV13)** and the **23-valent pneumococcal polysaccharide vaccine (PPSV23)** are crucial for protection, with PCV13 typically given first.
*Inactivated (intramuscular) influenza vaccine*
- While recommended annually for most individuals, especially those with chronic conditions, influenza vaccination is generally given in the **fall** (September-October) to cover the typical flu season.
- Administering it in June is **premature** and not the most urgent vaccination for this patient in a post-splenectomy state.
*Live attenuated (intranasal) influenza vaccine*
- This vaccine is also administered annually in the fall for seasonal influenza and is **contraindicated** in immunocompromised individuals.
- Patients who have undergone splenectomy are considered **immunocompromised**, making this vaccine unsuitable.
*Tetanus booster vaccine*
- This patient would have likely received a **tetanus vaccine** at the time of the motor vehicle collision if their vaccination status was unknown or incomplete, as it's indicated for traumatic wounds.
- There is no indication for an additional tetanus booster based on his current presentation or recent hospital stay.
*Measles-mumps-rubella vaccine*
- The patient was noted to be **up-to-date on all vaccinations** prior to the accident, implying he has likely already received the MMR vaccine.
- There is no specific indication for an additional MMR vaccine due to splenectomy, unlike for encapsulated bacteria.
Adult immunization recommendations US Medical PG Question 5: A 27-year-old G0P0 female presents to her OB/GYN for a preconception visit to seek advice before becoming pregnant. A detailed history reveals no prior medical or surgical history, and she appears to be in good health currently. Her vaccination history is up-to-date. She denies tobacco or recreational drug use and admits to drinking 2 glasses of wine per week. She states that she is looking to start trying to become pregnant within the next month, hopefully by the end of January. Which of the following is NOT recommended as a next step for this patient's preconception care?
- A. Begin 400 mcg folic acid supplementation
- B. Administer measles, mumps, rubella (MMR) vaccination (Correct Answer)
- C. Obtain rubella titer
- D. Obtain varicella zoster titer
- E. Recommend inactivated influenza vaccination
Adult immunization recommendations Explanation: ***Administer measles, mumps, rubella (MMR) vaccination***
- Live-attenuated vaccines like **MMR** are contraindicated during pregnancy and should ideally be given **at least one month prior to conception**.
- If her vaccination history is up-to-date and she plans to conceive within the month, administering MMR is not recommended at this time without confirming immunity first.
*Begin 400 mcg folic acid supplementation*
- **Folic acid supplementation** at 400 mcg daily is recommended for all women of childbearing age to prevent **neural tube defects**, ideally starting at least one month before conception and continuing through the first trimester.
- This is a crucial step in preconception care to ensure adequate levels when the neural tube is forming.
*Obtain rubella titer*
- Checking a **rubella titer** is standard preconception care to determine immunity, as rubella infection during pregnancy can lead to serious congenital anomalies.
- If she is not immune, the MMR vaccine can be offered, but with a **one-month contraception period** before attempting conception.
*Obtain varicella zoster titer*
- Determining **varicella immunity** is important because congenital varicella syndrome can occur if a non-immune mother contracts chickenpox during pregnancy.
- If she is not immune, the **varicella vaccine** can be administered, followed by a **one-month waiting period** before conception.
*Recommend inactivated influenza vaccination*
- **Inactivated influenza vaccination** is safe and recommended during any stage of pregnancy, including the preconception period, to protect both the mother and newborn from severe influenza outcomes.
- It can be given even if she plans to conceive within the month, as it is not a live vaccine.
Adult immunization recommendations US Medical PG Question 6: A 27-year-old man presents to the family medicine clinic for a routine check-up. The patient recently accepted a new job at a childcare center and the employer is requesting his vaccination history. After checking the records from the patient’s childhood, the physician realizes that the patient never had the varicella vaccine. The patient is unsure if he had chickenpox as a child, and there is no record of him having had the disease in the medical record. There is no significant medical history, and the patient takes no current medications. The patient’s heart rate is 82/min, respiratory rate is 14/min, temperature is 37.5°C (99.5°F), and blood pressure is 120/72 mm Hg. The patient appears alert and oriented. Auscultation of the heart reveals no murmurs, rubs, or gallops. The lungs are clear to auscultation bilaterally. With regard to the varicella vaccine, which of the following is recommended for the patient at this time?
- A. Two doses of vaccine (Correct Answer)
- B. One dose of the vaccine
- C. Wait until patient turns 50
- D. Serology then administer the vaccine (2 doses)
- E. Serology then administer the vaccine (1 dose)
Adult immunization recommendations Explanation: ***Two doses of vaccine***
- According to **CDC/ACIP guidelines**, adults without evidence of immunity to varicella should receive **two doses of varicella vaccine** (4-8 weeks apart) without prior serologic testing.
- The patient has no documentation of vaccination or prior disease, and works in a **high-risk setting (childcare center)** with frequent exposure to children.
- **Routine serologic testing is NOT recommended** before vaccination as it delays protection, is cost-ineffective, and the vaccine is safe even if the person is already immune.
- Two doses provide **97% protection** against varicella and significant protection against breakthrough disease.
*Serology then administer the vaccine (2 doses)*
- While the two-dose schedule is correct, obtaining serology first is **not recommended by CDC** for routine adult varicella vaccination.
- Serologic testing delays protection and is cost-ineffective; the vaccine is safe to give even if immunity already exists.
- Serology may be considered in special circumstances (e.g., for healthcare workers when cost-benefit analysis favors testing), but not routinely.
*One dose of the vaccine*
- A single dose provides only **80-85% protection** and is insufficient for adults.
- **Two doses are required** for optimal immunity in adults without evidence of immunity.
*Wait until patient turns 50*
- This confuses the **varicella (chickenpox) vaccine** with the **herpes zoster (shingles) vaccine** (Shingrix), which is recommended at age 50.
- The patient needs immediate protection due to high-risk occupational exposure and current susceptibility.
*Serology then administer the vaccine (1 dose)*
- This option is incorrect for two reasons: serology is not routinely recommended, and one dose is insufficient for adult vaccination.
- Adults require a **two-dose series** for adequate protection against varicella.
Adult immunization recommendations US Medical PG Question 7: A 19-year-old male arrives to student health for an annual check up. He is up to date on his infant and childhood vaccinations up to age 10. At age 12, he received a single dose of the tetanus, diphtheria, and acellular pertussis vaccine, and a quadrivalent meningococcal conjugate vaccine. A month ago, he received the influenza vaccine. The patient has no significant medical history. He takes over the counter ibuprofen for occasional headaches. He has a father with hypertension and hyperlipidemia, and his brother has asthma. He is sexually active with his current girlfriend. He denies tobacco use, illicit drug use, and recent or future travel. The patient’s temperature is 98°F (36.7°C), blood pressure is 118/78 mmHg, pulse is 70/min, and respirations are 14/min with an oxygen saturation of 99% O2 on room air. A physical examination is normal. What of the following is the best recommendation for vaccination?
- A. Human papillomavirus vaccine (Correct Answer)
- B. Hepatitis A vaccine
- C. Herpes zoster vaccine
- D. Pneumococcal vaccine
- E. Tetanus and reduced diphtheria toxoid booster
Adult immunization recommendations Explanation: ***Human papilloma virus***
- This patient, being 19 years old and **sexually active**, is a prime candidate for the **HPV vaccine** to prevent infections that can lead to various cancers.
- The CDC recommends routine HPV vaccination at age 11-12, but catch-up vaccination is recommended for individuals up to age 26 if not adequately vaccinated previously.
*Hepatitis A vaccine*
- The Hepatitis A vaccine is generally recommended for individuals at **increased risk** of infection, such as travelers to endemic areas, men who have sex with men, or those with chronic liver disease, none of which apply to this patient.
- There is no indication for routine vaccination without specific risk factors in this otherwise healthy young male.
*Herpes zoster vaccine*
- The herpes zoster (shingles) vaccine is recommended for adults **age 50 years and older** to prevent shingles.
- This patient is only 19 years old, making him too young for this vaccine recommendation.
*Pneumococcal vaccine*
- Pneumococcal vaccines (PCV13 and PPSV23) are typically recommended for **young children**, adults **65 years and older**, or individuals with **certain underlying medical conditions** (e.g., chronic heart, lung, or kidney disease, or immunocompromised states).
- This 19-year-old patient has no such risk factors for pneumococcal disease.
*Tetanus and reduced diphtheria toxoid booster*
- The patient received a Tdap vaccine at age 12. A Td booster is recommended **every 10 years** for adults.
- Since it has been only 7 years since his last Tdap vaccine, he is not due for a Td booster at this time.
Adult immunization recommendations US Medical PG Question 8: A 1-year-old immigrant girl has not received any recommended vaccines since birth. She attends daycare and remains healthy despite her daily association with several other children for the past 3 months at a home day-care facility. Which of the following phenomena explains why she has not contracted any vaccine-preventable diseases such as measles, diphtheria, or pertussis?
- A. Herd immunity (Correct Answer)
- B. Immune evasion
- C. Tolerance
- D. Genetic drift
- E. Genetic shift
Adult immunization recommendations Explanation: ***Herd immunity***
- **Herd immunity** occurs when a significant portion of a population is immune to a disease, providing **indirect protection** to unvaccinated individuals.
- In a daycare setting with vaccinated children, the low prevalence of disease agents protects the unvaccinated girl.
*Immune evasion*
- **Immune evasion** refers to mechanisms used by pathogens to **avoid detection** and destruction by the host immune system.
- This concept describes how a pathogen survives in an infected individual, not why an uninfected individual avoids disease.
*Tolerance*
- **Tolerance** in immunology is a state of **unresponsiveness to antigens**, preventing the immune system from attacking self-components or harmless foreign substances.
- It does not explain protection from infectious diseases; rather, it's about not mounting an immune response when one is usually expected.
*Genetic drift*
- **Genetic drift** is a change in the frequency of an existing gene variant (allele) in a population due to **random sampling** of organisms.
- This is a concept in population genetics that does not explain an individual's protection from infectious disease.
*Genetic shift*
- **Genetic shift** (antigenic shift) refers to an **abrupt, major change** in the influenza virus, leading to new hemagglutinin and/or neuraminidase proteins.
- This phenomenon explains the emergence of new influenza strains, not the protection of an individual from vaccine-preventable diseases.
Adult immunization recommendations US Medical PG Question 9: A 45-year-old man with a history of poorly controlled human immunodeficiency virus (HIV) infection presents to the emergency room complaining of clumsiness and weakness. He reports a 3-month history of worsening balance, asymmetric muscle weakness, and speech difficulties. He recently returned from a trip to Guatemala to visit his family. He has been poorly compliant with his anti-retroviral therapy and his most recent CD4 count was 195. His history is also notable for rheumatoid arthritis and hepatitis C. His temperature is 99°F (37.2°C), blood pressure is 140/90 mmHg, pulse is 95/min, and respirations are 18/min. On exam, he has 4/5 strength in his right upper extremity, 5/5 strength in his left upper extremity, 5/5 strength in his right lower extremity, and 3/5 strength in his left lower extremity. His speech is disjointed with intermittent long pauses between words. Vision is 20/100 in the left eye and 20/40 in his right eye; previously, his eyesight was 20/30 bilaterally. This patient most likely has a condition caused by which of the following types of pathogens?
- A. Arenavirus
- B. Bunyavirus
- C. Herpesvirus
- D. Polyomavirus (Correct Answer)
- E. Picornavirus
Adult immunization recommendations Explanation: ***Polyomavirus***
- The patient's **poorly controlled HIV**, **low CD4 count (195)**, and progressive neurological symptoms (clumsiness, weakness, speech difficulties, vision changes) are highly suggestive of **Progressive Multifocal Leukoencephalopathy (PML)**.
- PML is caused by the **JC virus**, which is a type of **polyomavirus**, typically reactivating in immunocompromised individuals.
*Arenavirus*
- Arenaviruses (e.g., Lassa fever virus) are known to cause **hemorrhagic fevers** and can lead to neurological complications, but the clinical presentation described (progressive focal neurological deficits in an HIV patient) is not typical for an arenavirus infection.
- While some arenaviruses cause **meningoencephalitis**, the progressive, demyelinating-like course seen in this patient points away from arenavirus.
*Bunyavirus*
- Bunyaviruses (e.g., Hantavirus, La Crosse encephalitis virus) can cause **encephalitis**, fever, and myalgia, but they don't typically present with the specific constellation of **progressive white matter lesions** and focal neurological signs characteristic of PML in an HIV patient.
- Hantaviruses are more associated with **hemorrhagic fever with renal syndrome** or **hantavirus cardiopulmonary syndrome**.
*Herpesvirus*
- While herpesviruses (e.g., HSV, CMV, VZV) can cause severe neurological disease in HIV patients (e.g., **CMV encephalitis**, **HSV encephalitis**, **VZV vasculopathy**), the described progressive multifocal deficits, especially with rapid worsening, in an HIV patient with a low CD4 count strongly favor PML.
- Herpesviral encephalitides often present with more acute onset, fever, and seizures, or specific radiographic patterns not directly matching PML.
*Picornavirus*
- Picornaviruses, such as enteroviruses, can cause **aseptic meningitis** or **encephalitis**, particularly in immunocompromised individuals.
- However, the progressive, multifocal neurological deficits, particularly affecting **white matter**, are not characteristic of picornavirus infections, which tend to cause more diffuse or acute inflammatory processes.
Adult immunization recommendations US Medical PG Question 10: A 48-year-old man with HIV comes to the physician because of skin lesions over his face and neck for 2 weeks. They are not itchy or painful. He does not have fever or a sore throat. He was treated for candidal esophagitis 3 months ago. He is sexually active with his wife, who knows of his condition, and uses condoms consistently. He is currently receiving triple antiretroviral therapy with lamivudine, abacavir, and efavirenz. He is 175 cm (5 ft 9 in) tall and weighs 58 kg (128 lb); BMI is 18.8 kg/m2. Examination shows multiple skin colored papules over his face and neck with a dimpled center. Cervical lymphadenopathy is present. The remainder of the examination is unremarkable. His hemoglobin concentration is 12.1 g/dL, leukocyte count is 4,900/mm3, and platelet count is 143,000/mm3; serum studies and urinalysis show no abnormalities. CD4+ T-lymphocyte count is 312/mm3 (normal ≥ 500). Which of the following is the most likely cause of this patient's findings?
- A. Poxvirus (Correct Answer)
- B. A herpesvirus
- C. Papillomavirus
- D. Coccidioides
- E. Bartonella
Adult immunization recommendations Explanation: ***Poxvirus***
- The description of **skin-colored papules with a dimpled (umbilicated) center** is highly characteristic of **molluscum contagiosum**, which is caused by a poxvirus. This condition is common in immunocompromised individuals, such as those with HIV.
- The patient's **HIV-positive status** and **CD4+ count of 312/mm³** indicate immunocompromise, making him susceptible to severe or widespread molluscum contagiosum, often seen on the face and neck.
*A herpesvirus*
- Herpes simplex virus typically causes **painful, clustered vesicles** on an erythematous base, often with recurrent outbreaks; this presentation does not match the described painless, umbilicated papules.
- Varicella-zoster virus (another herpesvirus) causes chickenpox or shingles, presenting as **vesicles and crusts in a dermatomal pattern** (shingles) or diffuse rash (chickenpox), which is inconsistent with this patient's lesions.
*Papillomavirus*
- Human papillomavirus (HPV) causes **warts**, which are typically rough, hyperkeratotic papules or nodules, lacking the characteristic central umbilication seen in this patient.
- While common in immunocompromised individuals, HPV lesions usually present differently and are not described as skin-colored with a dimpled center.
*Coccidioides*
- **Coccidioidomycosis** is a fungal infection that can cause various skin manifestations, including **erythema nodosum**, **erythema multiforme**, or subcutaneous nodules, but not the distinct umbilicated papules characteristic of molluscum contagiosum.
- Systemic symptoms like fever, cough, and fatigue are common in disseminated coccidioidomycosis, and while skin lesions can occur, they do not typically present as solitary or multiple umbilicated papules.
*Bartonella*
- *Bartonella* infections, particularly *Bartonella henselae* (cat scratch disease) or *Bartonella quintana* (bacillary angiomatosis), typically present as **reddish-purple vascular lesions** (angiomatous papules or nodules) or localized lymphadenopathy.
- The lesions described are skin-colored and umbilicated, not vascular, making *Bartonella* an unlikely cause.
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