L14 QS, BMS201.pdf

Certainly, let's generate 40 MCQs based on the provided lecture content, maintaining a balance of medium and high difficulty levels, and focusing on the key points. MCQs on Blood Stream Infections and Staphylococci Medium Difficulty 1. Which of the following terms refers to the presence of viable...

Certainly, let's generate 40 MCQs based on the provided lecture content, maintaining a balance of medium and high difficulty levels, and focusing on the key points. MCQs on Blood Stream Infections and Staphylococci Medium Difficulty 1. Which of the following terms refers to the presence of viable bacteria in the blood, regardless of symptoms? ○ a) Septicemia ○ b) Bacteremia ○ c) Toxemia ○ d) Viremia 2. Septicemia is characterized by: ○ a) The presence of bacteria in the blood without multiplication ○ b) The presence and multiplication of bacteria in the blood ○ c) The release of toxins into the blood from a localized infection ○ d) The presence of viruses in the blood 3. Which of the following is a life-threatening organ dysfunction caused by a dysregulated host response to infection? ○ a) Bacteremia ○ b) Sepsis ○ c) Toxemia ○ d) Viremia 4. What is the primary means of establishing a diagnosis of sepsis? ○ a) Blood culture ○ b) PCR ○ c) Urine culture ○ d) Sputum culture 5. Which Staphylococcus species is coagulase-positive? ○ a) Staphylococcus aureus ○ b) Staphylococcus epidermidis ○ c) Staphylococcus saprophyticus ○ d) All of the above 6. Which of the following is NOT a characteristic of Staphylococcus aureus? ○ a) Gram-positive cocci in clusters ○ b) Non-motile ○ c) Spore-forming ○ d) Facultative anaerobe 7. Which enzyme produced by S. aureus converts fibrinogen to fibrin, contributing to its virulence? ○ a) Coagulase ○ b) Staphylokinase ○ c) Catalase ○ d) DNase 8. Which S. aureus toxin is responsible for scalded skin syndrome in neonates? ○ a) Enterotoxin  ○ b) Toxic shock syndrome toxin (TSST-1) ○ c) Epidermolytic (exfoliative) toxin ○ d) Leukocidin 9. Which of the following is NOT a typical disease caused by S. aureus? ○ a) Impetigo ○ b) Pneumonia ○ c) Meningitis ○ d) Typhoid fever 10. Toxic shock syndrome (TSS) is most commonly associated with: ○ a) Food poisoning ○ b) Tampon use ○ c) Skin infections ○ d) Pneumonia 11. Which of the following is a selective medium for the isolation of S. aureus? ○ a) Blood agar ○ b) Mannitol salt agar ○ c) MacConkey agar ○ d) Chocolate agar 12. Which test differentiates Staphylococcus from Streptococcus based on their ability to break down hydrogen peroxide? ○ a) Coagulase test ○ b) Catalase test ○ c) DNase test ○ d) Novobiocin susceptibility test 13. Which Staphylococcus species is a common cause of urinary tract infections in young females? ○ a) Staphylococcus aureus ○ b) Staphylococcus epidermidis ○ c) Staphylococcus saprophyticus ○ d) None of the above 14. Which of the following statements about methicillin-resistant Staphylococcus aureus (MRSA) is FALSE? ○ a) MRSA is resistant to methicillin and often multiple other antibiotics ○ b) MRSA infections are typically nosocomial (hospital-acquired) ○ c) MRSA can be treated with vancomycin ○ d) MRSA is less virulent than methicillin-susceptible S. aureus (MSSA) 15. Which of the following is NOT a virulence factor of Staphylococcus aureus? ○ a) Coagulase ○ b) Protein A ○ c) Capsule ○ d) Flagella 16. Which of the following statements about Staphylococcus epidermidis is TRUE? ○ a) It is a coagulase-positive Staphylococcus ○ b) It is a major cause of community-acquired infections ○ c) It is part of the normal skin flora but can cause nosocomial infections ○ d) It is highly susceptible to all antibiotics 17. Which test is used to differentiate between S. epidermidis and S. saprophyticus? ○ a) Coagulase test  ○ b) Catalase test ○ c) DNase test ○ d) Novobiocin susceptibility test High Difficulty 18. Which of the following statements about blood stream infections (BSIs) is FALSE? ○ a) Primary BSIs originate from an infection at another body site ○ b) Secondary BSIs are seeded from a site-specific infection ○ c) Community-acquired BSIs have an onset of symptoms within 48 hours of admission ○ d) Nosocomial BSIs are acquired in a healthcare setting 19. Which of the following is an example of continuous bacteremia? ○ a) Transient bacteremia following dental procedures ○ b) Intermittent bacteremia from an abdominal abscess ○ c) Bacteremia in the first week of typhoid fever ○ d) Bacteremia caused by a urinary tract infection 20. Which of the following is NOT a typical causative agent of gram-negative bacteremia? ○ a) Escherichia coli ○ b) Klebsiella pneumoniae ○ c) Streptococcus pneumoniae ○ d) Pseudomonas aeruginosa 21. Which of the following statements about the pathogenesis of S. aureus infections is TRUE? ○ a) S. aureus relies solely on its toxins to cause disease ○ b) S. aureus can evade the immune system by producing coagulase and protein A ○ c) S. aureus is unable to survive within phagocytic cells ○ d) S. aureus infections are always localized and do not spread to the bloodstream 22. Which of the following is NOT a mechanism by which S. aureus enterotoxins cause food poisoning? ○ a) They are heat-stable and resist cooking ○ b) They are acid-stable and resist digestion in the stomach ○ c) They stimulate the immune system, leading to an inflammatory response ○ d) They directly damage the intestinal lining, causing vomiting and diarrhea 23. The desquamation of skin seen in toxic shock syndrome (TSS) is caused by: ○ a) The direct action of S. aureus on the skin ○ b) The release of exfoliative toxins ○ c) The host's immune response to the infection ○ d) Dehydration 24. Which of the following statements about the laboratory diagnosis of S. aureus infections is FALSE? ○ a) Gram stain can be used to identify the characteristic grape-like clusters of gram-positive cocci ○ b) Culture on blood agar can demonstrate beta-hemolysis ○ c) The coagulase test is used to differentiate S. aureus from other staphylococci ○ d) The catalase test is used to confirm the presence of S. aureus 25. Which of the following is the most appropriate treatment for MRSA infections? ○ a) Penicillin  ○ b) Methicillin ○ c) Vancomycin ○ d) Amoxicillin 26. Which of the following is NOT a risk factor for developing nosocomial bloodstream infections caused by coagulase-negative staphylococci? ○ a) Presence of indwelling medical devices ○ b) Immunosuppression ○ c) Prolonged hospital stay ○ d) Recent travel to a developing country 27. Which of the following statements about the differences between staphylococcal species is FALSE? ○ a) S. aureus is coagulase-positive, while S. epidermidis and S. saprophyticus are coagulase-negative ○ b) S. aureus produces a variety of exotoxins, while S. epidermidis and S. saprophyticus do not ○ c) S. saprophyticus is resistant to novobiocin, while S. epidermidis is sensitive ○ d) All three species are catalase-positive 28. Which of the following is NOT a mechanism by which S. aureus evades the host immune system? ○ a) Production of coagulase ○ b) Production of protein A ○ c) Formation of a capsule ○ d) Production of leukocidins 29. Which of the following is a key difference between S. epidermidis and S. saprophyticus on blood agar? ○ a) S. epidermidis causes alpha-hemolysis, while S. saprophyticus causes beta-hemolysis ○ b) S. epidermidis causes beta-hemolysis, while S. saprophyticus causes alpha-hemolysis ○ c) Both species cause gamma-hem Certainly, let's complete the set of MCQs based on the lecture content, ensuring a mix of medium and high difficulty questions while emphasizing key points. Medium Difficulty (Continued) 18. Which of the following is NOT a characteristic of toxic shock syndrome (TSS)? ○ a) High fever ○ b) Hypotension ○ c) Rash ○ d) Constipation 19. Which of the following statements about Staphylococcus saprophyticus is FALSE? ○ a) It is coagulase-negative ○ b) It is novobiocin resistant ○ c) It is a common cause of pneumonia ○ d) It is a gram-positive coccus 20. Which of the following is NOT a typical specimen collected for the laboratory diagnosis of S. aureus infections? ○ a) Pus from a skin lesion ○ b) Blood culture ○ c) Cerebrospinal fluid ○ d) Throat swab 21. Which of the following statements about the Gram stain of Staphylococcus is TRUE? ○ a) It appears as gram-negative cocci in chains ○ b) It appears as gram-positive cocci in clusters ○ c) It appears as gram-negative rods ○ d) It appears as gram-positive bacilli 22. Which of the following enzymes is NOT produced by S. aureus? ○ a) Coagulase ○ b) Hyaluronidase ○ c) Urease ○ d) Lipase 23. Which of the following statements about S. aureus food poisoning is TRUE?  ○ a) It has a long incubation period (24-48 hours) ○ b) It is characterized by fever and bloody diarrhea ○ c) It is caused by the ingestion of pre-formed enterotoxins ○ d) It is treated with antibiotics 24. Which of the following is NOT a typical site of infection for coagulase-negative staphylococci (CoNS)? ○ a) Bloodstream ○ b) Heart valves ○ c) Peritoneum ○ d) Lungs 25. Which of the following is the most common clinical manifestation of S. saprophyticus infection? ○ a) Pneumonia ○ b) Skin infections ○ c) Urinary tract infections ○ d) Endocarditis 26. Which of the following statements about the normal flora is FALSE? ○ a) They are microorganisms that colonize the body without causing harm ○ b) They can compete with pathogens and prevent infections ○ c) They are always beneficial to the host ○ d) They can be opportunistic pathogens under certain conditions 27. Which of the following is NOT a mechanism by which bacteria can enter the bloodstream? ○ a) Through breaks in the skin or mucous membranes ○ b) From a focus of infection elsewhere in the body  ○ c) Through inhalation of contaminated air ○ d) Through the use of contaminated needles High Difficulty 28. Which of the following is a key distinction between transient and intermittent bacteremia? ○ a) Transient bacteremia is associated with fever, while intermittent bacteremia is not ○ b) Transient bacteremia is caused by gram-positive bacteria, while intermittent bacteremia is caused by gram-negative bacteria ○ c) Transient bacteremia is self-limiting, while intermittent bacteremia can persist for longer periods ○ d) Transient bacteremia is always associated with an underlying infection, while intermittent bacteremia is not 29. Which of the following is NOT a typical mechanism of antibiotic resistance in Staphylococci? ○ a) Production of beta-lactamases ○ b) Alteration of penicillin-binding proteins ○ c) Efflux pumps ○ d) Production of endotoxins 30. Which of the following statements about the role of the microcapsule in S. aureus virulence is TRUE? ○ a) It facilitates adherence to host tissues ○ b) It inhibits phagocytosis ○ c) It promotes biofilm formation  ○ d) It enhances toxin production 31. Which of the following is NOT a potential complication of S. aureus bacteremia? ○ a) Endocarditis ○ b) Osteomyelitis ○ c) Septic arthritis ○ d) Glomerulonephritis 32. Which of the following is a key difference between the toxins produced by S. aureus and the toxins produced by gram-negative bacteria? ○ a) S. aureus toxins are heat-stable, while gram-negative toxins are heat-labile ○ b) S. aureus toxins are released from the bacterial cell, while gram-negative toxins are part of the cell wall ○ c) S. aureus toxins cause localized symptoms, while gram-negative toxins cause systemic symptoms ○ d) S. aureus toxins are primarily exotoxins, while gram-negative toxins are primarily endotoxins 33. Which of the following is NOT a typical laboratory test used to identify Staphylococci? ○ a) Gram stain ○ b) Culture ○ c) Biochemical tests (e.g., catalase, coagulase, DNase) ○ d) Antibiotic susceptibility testing ○ e) Indole test 34. Which of the following is a key virulence factor that allows S. epidermidis  to cause infections associated with indwelling medical devices? ○ a) Production of coagulase ○ b) Ability to form biofilms ○ c) Production of enterotoxins ○ d) Resistance to novobiocin 35. Which of the following statements about the epidemiology of bloodstream infections is FALSE? ○ a) Gram-positive bacteria are the most common cause of BSIs ○ b) Nosocomial BSIs are often associated with healthcare-associated procedures ○ c) Community-acquired BSIs are typically less severe than nosocomial BSIs ○ d) The incidence of BSIs has been increasing in recent years 36. Which of the following is NOT a typical clinical manifestation of bloodstream infections? ○ a) Fever ○ b) Hypotension ○ c) Tachycardia ○ d) Diarrhea ○ e) Skin rash 37. Which of the following is NOT a common source of nosocomial bloodstream infections? ○ a) Central venous catheters ○ b) Urinary catheters ○ c) Ventilators  ○ d) Contaminated food 38. Which of the following is a key challenge in the treatment of bloodstream infections? ○ a) The increasing prevalence of antibiotic resistance ○ b) The difficulty in identifying the causative agent ○ c) The lack of effective antibiotics ○ d) The high cost of treatment 39. Which of the following is NOT a strategy for preventing bloodstream infections? ○ a) Proper hand hygiene ○ b) Aseptic technique during medical procedures ○ c) Early removal of indwelling medical devices ○ d) Prophylactic antibiotic use in all hospitalized patients 40. Which of the following statements about the prognosis of bloodstream infections is TRUE? ○ a) The mortality rate for BSIs is very low ○ b) Early diagnosis and treatment improve the prognosis ○ c) The prognosis is the same for all types of BSIs ○ d) The prognosis is not affected by the patient's underlying health conditions Answer Key 1. b 2. b 3. b 4. a 5. a 6. c 7. a 8. c 9. d 10. b 11. b 12. b 13. c 14. d 15. d 16. c 17. d 18. a 19. c 20. c 21. b 22. c 23. c 24. d 25. c 26. c 27. c 28. c 29. d 30. b 31. d 32. d 33. e 34. b 35. c 36. e 37. d 38. c 39. d 40. b