1.
Which type of organism is responsible for the largest number of blood stream infections?
Correct Answer
B. B. Gram positive bacteria
Explanation
Gram positive bacteria are responsible for the largest number of blood stream infections. Gram positive bacteria have a thick peptidoglycan layer in their cell wall, which helps them to survive in different environments, including the bloodstream. They can cause various infections such as sepsis, endocarditis, and pneumonia. Gram positive bacteria include species like Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecalis, which are common causes of bloodstream infections. This is why gram positive bacteria are the most common type of organism responsible for blood stream infections.
2.
Which of the following correctly shows the order of taxonomic classification of bacteria?
Correct Answer
C. C. Family, genus, species
Explanation
The correct order of taxonomic classification of bacteria is family, genus, species. This means that bacteria are first classified into families, then further classified into genera, and finally into species. This hierarchical system allows for the organization and categorization of different bacteria based on their shared characteristics and evolutionary relationships.
3.
Which of the following statements does not describe gram negative bacteria?
Correct Answer
A. A. They have a thick, homogenous peptidoglycan sheath making up the cell wall
Explanation
Gram negative bacteria do not have a thick, homogenous peptidoglycan sheath making up the cell wall. Instead, they have a thin peptidoglycan layer sandwiched between an outer lipopolysaccharide (LPS) membrane and an inner cytoplasmic membrane. This structural difference is one of the key characteristics that distinguishes gram negative bacteria from gram positive bacteria.
4.
Why are gram stains valuable as a companion to molecular?
Correct Answer
G. All of the above
Explanation
Gram stains are valuable as a companion to molecular tests because they can aid in bacterial identification when a molecular test is negative. This is important because molecular tests may not always provide a definitive result, and the gram stain can provide additional information. Additionally, gram stains are required for selecting optimal growth media for sub-culture, which is necessary for determining the full susceptibility of bacteria to antibiotics. Skipping the gram stain is off-label for all FDA cleared MDx assays, indicating that it is a standard practice to perform a gram stain alongside molecular tests. Finally, gram stains may also aid in detecting polymicrobial infections, where multiple types of bacteria are present. Therefore, all of the given options are correct.
5.
True or false: Nosocomial infections and Community acquired infections are basically the same thing.
Correct Answer
B. False
Explanation
Nosocomial infections and community-acquired infections are not the same thing. Nosocomial infections refer to infections that are acquired in a healthcare setting, such as hospitals or clinics, while community-acquired infections are acquired outside of healthcare facilities, in the general community. The key difference lies in the location where the infection was acquired.
6.
Why is it important to know a patient’s history when diagnosing sepsis/blood stream infections?
Correct Answer
C. C. A patient’s history can help guide empiric antibiotic treatment while waiting for definitive test results
Explanation
Knowing a patient's history is important when diagnosing sepsis/blood stream infections because it can help guide empiric antibiotic treatment while waiting for definitive test results. The patient's history can provide valuable information about previous infections, antibiotic use, and underlying conditions that may affect the choice of antibiotics. This information can help the healthcare provider make an informed decision about which antibiotics to initiate immediately, before the results of specific diagnostic tests are available. This is crucial in sepsis cases, where prompt and appropriate antibiotic treatment is essential for improving patient outcomes.
7.
Which one of the following is more likely a true infection, rather than a contaminant?
Correct Answer
A. A. S. aureus
Explanation
S. aureus is more likely to be a true infection rather than a contaminant because it is a pathogenic bacterium commonly associated with various infections in humans, such as skin and soft tissue infections, pneumonia, and bloodstream infections. It is a common cause of hospital-acquired infections and is known to cause severe illnesses. On the other hand, Corynebacterium, Bacillus, and Propionibacterium are often found as contaminants and are less commonly associated with true infections.
8.
Why would a clinician draw multiple blood samples from different body sites on a patient?
Correct Answer
B. B. To rule out contamination introduced at the site of the blood draw
Explanation
A clinician may draw multiple blood samples from different body sites on a patient to rule out contamination introduced at the site of the blood draw. Drawing blood from multiple sites reduces the risk of contamination and ensures that the samples are accurate and reliable. This is especially important when conducting tests that require precise results, as contamination can lead to false readings. Therefore, drawing blood from different body sites helps to ensure the integrity of the samples and the accuracy of the test results.
9.
Which one of the following is not a common cause of gram positive bacteremia?
Correct Answer
C. C. Bacillus subtilus
Explanation
Bacillus subtilis is not a common cause of gram positive bacteremia. Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecium are all well-known causes of gram positive bacteremia. Bacillus subtilis is a common soil bacterium and is not typically associated with causing bloodstream infections in humans.
10.
Which of the following is an important, multi-drug resistant, gram negative bacteria?
Correct Answer
A. A. Acinetobacter baumannii
Explanation
Acinetobacter baumannii is an important, multi-drug resistant, gram-negative bacteria. This means that it is resistant to multiple types of antibiotics and belongs to a group of bacteria that do not retain the violet stain in the gram staining process. Acinetobacter baumannii is known for causing healthcare-associated infections, particularly in intensive care units, and it can cause a range of infections including pneumonia, bloodstream infections, and wound infections. Its multi-drug resistance makes it difficult to treat and control, posing a significant challenge in healthcare settings.
11.
What approximate % of blood stream infections are caused by fungi?
Correct Answer
B. B. 5-10%
Explanation
Approximately 5-10% of blood stream infections are caused by fungi.
12.
True or False: Gram-negative bacterial species tend to be more drug resistant.
Correct Answer
A. True
Explanation
Gram-negative bacterial species tend to be more drug resistant due to the presence of an outer membrane that acts as a barrier, making it harder for drugs to penetrate and reach their target inside the cell. This outer membrane contains porins, which are channels that selectively allow certain molecules to enter the cell. Additionally, Gram-negative bacteria have efflux pumps that actively pump out drugs, further contributing to their resistance. On the other hand, Gram-positive bacteria lack an outer membrane and are generally more susceptible to drugs.