Microbiolgy mcq test

Question 1

Which of the following is the gold standard for diagnosing tuberculosis?

Answer 1

C. Culture on Lowenstein-Jensen medium

Question 2

What is the most common cause of community-acquired pneumonia?

Answer 2

B. Streptococcus pneumoniae

Question 3

Which of the following pathogens is associated with ‘rose spots’ on the abdomen, hepatosplenomegaly, and ‘sphygmothermic dissociation’?

Answer 3

B. Salmonella typhi

Question 4

A patient develops a urinary tract infection with positive nitrites on dipstick. The most likely causative organism is:

Answer 4

B. Escherichia coli

Question 5

Which antibiotic class is considered ‘concentration-dependent killing with prolonged persistent effects’?

Answer 5

B. Aminoglycosides

Question 6

What is the classic histological finding in tuberculosis?

Answer 6

B. Caseating granulomas

Question 7

Which of the following is NOT a feature of severe falciparum malaria?

Answer 7

C. Splenomegaly

Question 8

A 25-year-old man presents with painless genital ulceration. Which of the following is LEAST likely to be the cause?

Answer 8

A. Herpes simplex virus

Question 9

What is the most appropriate first-line treatment for severe Clostridium difficile infection?

Answer 9

B. Vancomycin

Question 10

Which malaria species can cause relapse due to persistent liver forms (hypnozoites)?

Answer 10

C. Plasmodium vivax

Question 11

Which of the following antibiotics is associated with orange-colored secretions as a side effect?

Answer 11

B. Rifampicin

Question 12

An immunocompromised patient develops pneumonia with a ‘halo sign’ on CT scan. The most likely causative organism is:

Answer 12

B. Aspergillus

Question 13

Which of the following is the most appropriate treatment for gonorrhea?

Answer 13

C. Ceftriaxone

Question 14

A patient with HIV develops a dry cough, fever, shortness of breath, and weight loss. CXR shows a ‘batwing appearance.’ The likely diagnosis is:

Answer 14

B. Pneumocystis jirovecii pneumonia

Question 15

Which of the following CSF findings is most consistent with bacterial meningitis?

Answer 15

B. Turbid appearance, low glucose, polymorphs predominant

Question 16

The Duke criteria for diagnosis of infective endocarditis include all of the following EXCEPT:

Answer 16

D. Elevated C-reactive protein

Question 17

A returning traveler from Southeast Asia presents with fever, myalgia, retro-orbital headache, and a rash. The most likely diagnosis is:

Answer 17

B. Dengue fever

Question 18

Which of the following is NOT an atypical cause of pneumonia?

Answer 18

C. Streptococcus pneumoniae

Question 19

A patient with a prosthetic joint infection is most likely to be infected with:

Answer 19

B. Coagulase-negative staphylococci

Question 20

Which of the following is an appropriate empiric antibiotic treatment for severe community-acquired pneumonia?

Answer 20

C. Co-amoxiclav IV + Clarithromycin IV

Question 21

A patient presents with a ‘bullseye’ rash after hiking in a forested area. The most likely diagnosis is:

Answer 21

C. Lyme disease

Question 22

Which of the following is NOT a risk factor for tuberculosis?

Answer 22

C. Diabetes mellitus

Question 23

A patient develops a urinary tract infection with struvite stones. The most likely causative organism is:

Answer 23

B. Proteus mirabilis

Question 24

Which of the following is the first-line treatment for Pneumocystis jirovecii pneumonia?

Answer 24

B. Co-trimoxazole

Question 25

A patient with infective endocarditis develops Janeway lesions. These lesions are classified as:

Answer 25

B. Embolic phenomena

Question 26

Which of the following tests is most useful for diagnosing latent tuberculosis infection?

Answer 26

D. Interferon Gamma Release Assay (IGRA)

Question 27

A patient presents with a UTI. Their urine dipstick shows negative nitrites but positive leukocytes. The most likely causative organism is:

Answer 27

B. Staphylococcus saprophyticus

Question 28

Which of the following is NOT a feature of primary syphilis?

Answer 28

D. Rash on palms and soles

Question 29

A patient with pneumonia has dry cough, arthralgia, cold agglutinins, and erythema multiforme. The most likely causative organism is:

Answer 29

B. Mycoplasma pneumoniae

Question 30

The most appropriate treatment for severe Clostridium difficile infection is:

Answer 30

D. Vancomycin IV + Metronidazole IV

Question 31

Which of the following is the most common organism causing nosocomial pneumonia?

Answer 31

B. Enterobacteriaceae

Question 32

A neonate presents with persistent rhinitis, hepatosplenomegaly, jaundice, and a maculopapular rash progressing to desquamation. The most likely diagnosis is:

Answer 32

C. Congenital syphilis

Question 33

Which of the following is NOT a major Duke criterion for diagnosing infective endocarditis?

Answer 33

C. Fever

Question 34

Which of the following is the most common manifestation of reactivated tuberculosis?

Answer 34

B. Pulmonary disease

Question 35

What is a minor criterion in the Duke criteria for endocarditis?

Answer 35

Fever ## Footnote Major criteria are positive blood cultures and evidence of endocardial involvement.

Question 36

What is the most common manifestation of reactivated tuberculosis?

Answer 36

Pulmonary disease ## Footnote Usually presenting with upper lobe cavitation.

Question 37

Which virus is associated with 'owl's eye inclusions' on histology?

Answer 37

Human cytomegalovirus (HCMV) ## Footnote Cytomegalovirus (CMV) is characterized by 'owl's eye inclusions' on histology.

Question 38

A patient with a fever presents with Osler's nodes. What is the most likely diagnosis?

Answer 38

Infective endocarditis