Medicine
Infectious Disease
A patient with latent tuberculosis infection is about to start potent biologic immunosuppression. Why is screening and treatment important?
A. To reduce risk of TB reactivation
B. To prevent influenza
C. To cure bacterial pneumonia
D. Because biologics eliminate all vaccine responses
Correct Answer: A
Immunosuppression, especially certain biologic therapies, can reactivate latent tuberculosis, so risk assessment and treatment are important before therapy.
Medicine
Infectious Disease
A diabetic patient has rapidly progressive painful leg swelling, systemic toxicity and crepitus. What is the most appropriate management principle?
A. Urgent surgical exploration and broad-spectrum antibiotics
B. Topical antifungal cream only
C. Observe for 48 hours
D. Compression stockings only
Correct Answer: A
Necrotizing soft-tissue infection requires immediate surgical source control and broad empiric antimicrobial therapy.
Medicine
Infectious Disease
Which exposure is a major risk factor for brucellosis in the Gulf and Middle East?
A. Unpasteurized dairy products
B. Chlorinated drinking water
C. Cooked rice
D. Indoor air conditioning
Correct Answer: A
Brucellosis is associated with infected livestock and consumption of unpasteurized milk or dairy products.
Medicine
Infectious Disease
A patient with suspected dengue has fever, myalgia, thrombocytopenia and rising hematocrit. What does a rising hematocrit most strongly suggest?
A. Plasma leakage
B. Massive hemolysis only
C. Iron deficiency
D. Bacterial meningitis
Correct Answer: A
Hemoconcentration from capillary plasma leakage is a warning feature in dengue and can accompany progression toward shock.
Medicine
Infectious Disease
An immunocompromised patient has painful grouped vesicles in a dermatomal distribution. What is the diagnosis?
A. Herpes zoster
B. Impetigo
C. Molluscum contagiosum
D. Erysipelas
Correct Answer: A
Reactivation of varicella-zoster virus causes a painful unilateral vesicular eruption limited to a dermatome.
Medicine
Infectious Disease
A patient has fever, jaundice, renal failure and thrombocytopenia after freshwater exposure in a tropical area. Which infection should be considered?
A. Leptospirosis
B. Measles
C. Pertussis
D. Tinea corporis
Correct Answer: A
Severe leptospirosis can cause Weil disease with jaundice, renal failure and hemorrhagic manifestations after exposure to contaminated water.
Medicine
Infectious Disease
A patient with septic arthritis of the knee has fever, severe joint pain and a large effusion. What is the most important diagnostic procedure?
A. Urgent arthrocentesis for synovial analysis and culture
B. Serum uric acid only
C. Plain X-ray only
D. Wait for spontaneous improvement
Correct Answer: A
Septic arthritis is an emergency; synovial fluid analysis and culture are essential and should be obtained promptly.
Medicine
Infectious Disease
A patient presents after a dog bite from an animal suspected of rabies. What is the key principle of post-exposure prophylaxis in a previously unvaccinated person?
A. Wound cleansing, rabies vaccine and rabies immunoglobulin when indicated
B. Antibiotics alone
C. Tetanus vaccine alone
D. Observe for symptoms before any action
Correct Answer: A
Rabies PEP includes immediate wound care plus vaccine, with rabies immunoglobulin for category III exposures in previously unvaccinated patients when indicated.
Medicine
Infectious Disease
A patient has fever, severe headache and a petechial rash with hypotension. Which organism is a critical concern?
A. Neisseria meningitidis
B. Helicobacter pylori
C. Mycoplasma genitalium
D. Clostridium tetani
Correct Answer: A
Meningococcemia can progress rapidly with petechiae/purpura, shock and disseminated intravascular coagulation.
Medicine
Infectious Disease
A patient with tuberculosis is receiving rifampicin. Which counseling point is appropriate?
A. It may cause orange discoloration of body fluids
B. It never interacts with other drugs
C. It is safe to stop after symptoms improve
D. It causes universal deafness
Correct Answer: A
Rifampicin can discolor urine, tears and other secretions orange-red and is a potent enzyme inducer with important drug interactions.
Medicine
Infectious Disease
A patient with malaria has altered consciousness, severe anemia and renal impairment. What classification applies?
A. Severe malaria
B. Uncomplicated malaria
C. Latent malaria only
D. Malaria is excluded
Correct Answer: A
Neurologic dysfunction, severe anemia, kidney injury and other organ complications indicate severe malaria requiring urgent parenteral therapy.
Medicine
Infectious Disease
A patient with infective endocarditis has persistent Staphylococcus aureus bacteremia and a new murmur. Which diagnostic test is especially useful for detecting valvular vegetations when transthoracic echo is nondiagnostic?
A. Transesophageal echocardiography
B. Exercise ECG
C. Abdominal X-ray
D. Spirometry
Correct Answer: A
TEE has higher sensitivity than transthoracic echo for vegetations, abscesses and prosthetic-valve endocarditis.
Medicine
Infectious Disease
A patient with HIV has CD4 count 80 cells/mm3, dyspnea, dry cough and bilateral diffuse ground-glass infiltrates. What is the most likely diagnosis?
A. Pneumocystis jirovecii pneumonia
B. Lobar pneumococcal pneumonia
C. Pulmonary embolism
D. Aspergilloma
Correct Answer: A
Pneumocystis pneumonia classically occurs with advanced cellular immunosuppression and presents subacutely with dry cough, dyspnea and diffuse interstitial infiltrates.
Medicine
Infectious Disease
A hospitalized patient develops profuse watery diarrhea after clindamycin. Which organism is most likely?
A. Clostridioides difficile
B. Vibrio cholerae only
C. Giardia lamblia
D. Entamoeba histolytica
Correct Answer: A
Recent antibiotic exposure followed by healthcare-associated watery diarrhea strongly suggests C. difficile infection.
Medicine
Infectious Disease
A patient with fever, neck stiffness and altered mental status is suspected of bacterial meningitis. What should happen if lumbar puncture will be delayed for brain imaging?
A. Delay all treatment until LP
B. Obtain blood cultures and start empiric antibiotics promptly
C. Give only antipyretics
D. Start antifungal therapy only
Correct Answer: B
When bacterial meningitis is suspected, antimicrobial treatment should not be delayed for imaging or lumbar puncture after blood cultures are obtained when feasible.
Medicine
Infectious Disease
Which hepatitis B marker generally indicates current infection?
A. Anti-HBs alone
B. Isolated anti-HAV IgG
C. Anti-HCV antibody alone
D. Hepatitis B surface antigen (HBsAg)
Correct Answer: D
HBsAg positivity indicates current HBV infection, while anti-HBs generally reflects immunity.
Medicine
Infectious Disease
Which complication or major adverse outcome is particularly associated with Chronic hepatitis B infection?
A. Toxic megacolon
B. Cerebral malaria
C. Cirrhosis and hepatocellular carcinoma
D. Sensorineural hearing loss
Correct Answer: C
Chronic HBV can lead to progressive fibrosis, cirrhosis and liver cancer.
Medicine
Infectious Disease
A patient is diagnosed with Chronic hepatitis B infection. Which is the most appropriate management principle?
A. Start effective combination antiretroviral therapy and address opportunistic-infection prevention and treatment
B. Use specialist-guided antiviral therapy for patients meeting treatment criteria and perform appropriate liver-cancer surveillance in at-risk groups
C. Stop unnecessary precipitating antibiotics and use recommended C. difficile-directed therapy based on severity and recurrence
D. Use species- and severity-appropriate antimalarial therapy; severe malaria requires urgent parenteral treatment
Correct Answer: B
Nucleos(t)ide therapy suppresses HBV replication; surveillance and household or contact prevention are also important.
Medicine
Infectious Disease
In a patient with suspected Chronic hepatitis B infection, which investigation or diagnostic approach is most appropriate at this stage?
A. HBV serology, HBV DNA, liver assessment and evaluation for coinfections
B. Microbiologic testing of respiratory specimens with rapid molecular testing and culture
C. Laboratory HIV antigen/antibody testing with confirmatory testing according to the diagnostic algorithm
D. Stool testing using an accepted C. difficile diagnostic algorithm in a patient with clinically significant diarrhea
Correct Answer: A
Viral replication, liver injury and fibrosis determine monitoring and treatment decisions.
Medicine
Infectious Disease
A patient has persistently positive hepatitis B surface antigen with abnormal liver enzymes. What is the most likely diagnosis?
A. Nonpurulent cellulitis
B. Pulmonary tuberculosis
C. Human immunodeficiency virus (HIV) infection
D. Chronic hepatitis B infection
Correct Answer: D
Persistent HBsAg indicates chronic HBV infection and requires staging for liver disease and treatment need.