MCQs on Bloodstream infections and microorganisms (pathogens): Medical microbiology

                                       MCQs on Bloodstream pathogen

1. Which of the following bacterial pathogen is often associated with healthcare-associated bloodstream infections and is notorious for its antibiotic resistance?
a) Enterococcus faecalis
b) Pseudomonas aeruginosa    
c) Streptococcus pneumoniae 
d) Salmonella enterica

2. Which of the following bacterial pathogen can cause severe bloodstream infections in pregnant women, the elderly, and immunocompromised individuals, often associated with consumption of contaminated food?
a) Enterococcus faecalis
b) Escherichia coli
c) Salmonella enterica   
d) Streptococcus pneumoniae

3. In septicemia, what occurs due to a dysregulated response to infection?
a) Bacterial colonization
b) Localized infection
c) Mild fever
d) Organ dysfunction   

4. What is the most common cause of fungal bloodstream infections (fungemia)?
a) Aspergillus fumigatus
b) Candida albicans    
c) Cryptococcus neoformans
d) Candida auris

5. Which of the following fungal species is often associated with bloodstream infections in immunocompromised individuals, particularly those with HIV/AIDS?
a) Aspergillus niger
b) Candida glabrata
c) Cryptococcus neoformans    
d) Candida krusei

6. Which of the following pathogen is a common cause of  parasitic bloodstream infections?
a) Brucella abortus
b) Cryptococcus neoformans
c) Mycobacterium tuberculosis
d) Plasmodium falciparum   

7. A patient presents with fever, chills, and systemic symptoms. The blood culture reveals the presence of bacteria actively circulating in the bloodstream. What type of infection is likely present?
a) Extravascular infection
b) Localized infection
c) Intravascular infection    
d) Tissue infection

8. A skin and soft tissue infection that is localized and has not spread into the bloodstream is an example of a:
a) Bacteremia
b) Extravascular infection    
c) Fungemia
d) Intravascular infection

9. Which of the following gram positive bacteria is a common causative agent of infective endocarditis, especially in cases involving damaged heart valves?
a) Escherichia coli
b) Pseudomonas aeruginosa    
c) Streptococcus pneumoniae
d) Staphylococcus aureus    

10. Infective endocarditis is primarily an infection of which part of the heart?
a) Endocardium     
b) Epicardium
c) Myocardium
d) Pericardium

11. Recovery of Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella (HACEK) organisms from blood cultures is most commonly linked to which medical condition?
a) Infective endocarditis    
b) Pneumonia
c) Skin and soft tissue infections
d) Urinary tract infections

12. Which of the following gram negative bacteria residing as a normal oral flora of cats and dogs if transmitted to humans can cause bacteremia particularly in individuals with compromised immune systems or underlying health conditions?
a) Brucella abortus
b) Capnocytophaga canimorsus
c) Candida albicans
d) Staphylococcus aureus

13. Which of the following bacterial pathogen is primarily transmitted to humans through the bite of infected ticks and cause Lyme disease (skin rashes). If left untreated the infection can lead to bloodstream infections with severe symptoms, including joint pain, neurological symptoms, and cardiac issues?
a) Brucella abortus
b) Borrelia recurrentis
c) Capnocytophaga canimorsus
d) Mycoplasma hominis

14. Which of the following virus primarily invades lymphocytes and is known for causing diseases such as infectious mononucleosis and certain cancers?
a) Cytomegalovirus
b) Human immunodeficiency virus (HIV)
c) Epstein-Barr virus
d) Influenza virus

15. Which of the following virus specifically involves CD4+ T lymphocytes and macrophages, leading to a progressive immunosuppressive disease?
a) Cytomegalovirus
b) Epstein-Barr virus
c) Influenza virus
d) Human immunodeficiency virus (HIV)

16. Which term is used to describe a transient and asymptomatic presence of bacteria in the bloodstream, often resulting from nonsterile procedures or dental work?
a) Continuous bacteremia
b) Intermittent bacteremia
c) Septicemia
d) Transient bacteremia     

17. What is septicemia primarily characterized by?
a) A systemic and often life-threatening response to infection   
b) A fungal infection
c) An isolated skin rash
d) A localized infection in a specific organ

18. In the progression of septicemia, what stage follows severe sepsis?
a) Mild sepsis
b) Septic shock
c) Sepsis crisis
d) Septic organ dysfunction

19. How do arthroconidia of Coccidioides immitis and microconidia of Histoplasma capsulatum typically enter the bloodstream during systemic fungal infections?
a) Absorbed through the skin
b) Carried by lymphatic vessels to the blood
c) Ingested by alveolar macrophages in the lung
d) Ingested by alveolar macrophages in the liver

20. What are the common symptoms of sepsis or septicemia, which are primarily caused by the presence of invading microorganisms and their toxins?
a) Fever, chills, and malaise
b) Joint pain and rash
c) Nausea and vomiting
d) Rapid breathing and cough

21. Health care-associated bloodstream infections are often associated with the presence of which of the following?
a) Antibiotic-resistant organisms
b) Intravascular catheters or devices
c) Immunocompromised individuals
d) Localized infection

22. Which of the following strains of bacteria are common for causing intravenous catheter–associated bacteremia due to their ability to produce a biofilm on the catheter's surface?
a) Candida albicans
b) COVID-19 
c) Staphylococcus spp.
d) Treponema pallidum

23. Which of the following bacteria are commonly associated with bloodstrem infections from genitourinary tract infections (extravascular sites)?
a) Coagulase negative staphylococci
b) Proteus spp
c) Pseudomonas aeruginosa
d) Legionella spp.

24. What defines a health care-associated bloodstream infection (HA-BSI)?
a) A positive blood culture that occurs before admission to a health care facility
b) A positive blood culture that occurs within 2 days of admission to a health care facility
c) A positive blood culture that occurs 7 days after admission to a health care facility
d) A positive blood culture that occurs 2 weeks after admission to a health care facility


1. b) Pseudomonas aeruginosa 
2. c) Salmonella enterica 
3. d) Organ dysfunction 
4. b) Candida albicans
5. c) Cryptococcus neoformans
6. d) Plasmodium falciparum  
7. c) Intravascular infection 
8. b) Extravascular infection  
9. d) Staphylococcus aureus 
10. a) Endocardium  
11. a) Infective endocarditis
12. b) Capnocytophaga canimorsus
13. b) Borrelia recurrentis
14. c) Epstein-Barr virus
15. d) Human immunodeficiency virus (HIV)
16. d) Transient bacteremia

17. a) A systemic and often life-threatening response to infection. Septicemia, also known as sepsis, is a serious medical condition characterized by a systemic and often life-threatening response to an infection. It occurs when the body's response to an infection causes widespread inflammation, which can lead to organ dysfunction or failure.   
18. b) Septic shock.  Sepsis can vary in severity, from sepsis (mild) to severe sepsis (more serious) and septic shock (life-threatening). Septic shock is characterized by a significant drop in blood pressure, which can lead to multiple organ failure.

19. c) Ingested by alveolar macrophages in the lung

20. a) Fever, chills, and malaise
21. b) Intravascular catheters or devices
22. c) Staphylococcus spp.
23. b) Proteus spp
24. b) A positive blood culture that occurs within 2 days of admission to a health care facility