Question 1

The laboratory report concludes that the diagnosis is salmonellosis caused by Salmonella infection. Remembering resources available for prokaryotic identification, the RN speculates that the laboratory technicians may have used

Accepted Answer

The best choice is D because Bergey's Manual of Determinative Bacteriology is commonly used in clinical settings to identify bacteria based on their phenotypic traits, such as Gram stain, shape, and biochemical tests. This is the most likely resource used by the laboratory technicians in identifying the Salmonella infection. Choice A is not the best choice because rRNA analysis is not typically used in clinical settings for bacterial identification. Choice B is also not the best choice because the five volumes of Bergey's Manual of Systematic Bacteriology are not commonly used in clinical settings, especially for routine bacterial identification. Choice C is not the best choice because understanding the evolutionary background of the pathogen is not typically necessary for routine clinical identification of bacterial pathogens.

Question 2

A 23 year-old female presents at a walk-in clinic with a fever, swollen lymph nodes and yellow spots on the throat. A rapid strep test comes back positive, confirming an infection with Streptococcus pyogenes, which has a thick layer of peptidoglycan in its cell wall. In which of the following taxonomic divisions does S. pyogenes belong?

Accepted Answer

S. pyogenes belongs to the taxonomic division Firmicutes, which is characterized by bacteria with a thick layer of peptidoglycan in their cell walls. This division also includes other important bacteria such as Staphylococcus, Bacillus, and Clostridium.

Question 3

The patient is diagnosed with Salmonella enterica serovar Enteritidis infection, a foodborne illness. The identification of the bacterial subspecies is important for developing his treatment plan and was possible due to ________.

Accepted Answer

The identification of specific bacterial serovars, such as Salmonella enterica serovar Enteritidis, often involves serological methods, which include the analysis of antibody reactions against the pathogen. This approach helps in distinguishing between different serovars based on their unique surface antigens.

Question 4

The typical definition of a species is one with distinct characteristics that produce viable offspring when mated with another organism in the same species. Bacterial species cannot be defined as readily, due to the fact that

Accepted Answer

All of the statements are true regarding the indistinct defining of bacterial species. Bacteria do not reproduce sexually, but can receive genetic material from others in their generation through processes such as horizontal gene transfer. They also have a short generation time and can rapidly evolve, making it difficult to define distinct characteristics for each species. Therefore, bacterial species are not defined as readily as other organisms.

Question 5

Testing is performed on the specimen in the laboratory, including the Gram stain. This test separates bacteria into two broad classes: gram-positive and gram-negative. Which step in the staining process is the differential step, for it only acts upon one type of cell?

Accepted Answer

Decolorization with alcohol is the differential step in the Gram stain because it removes the crystal violet-iodine complex from the outer membrane of gram-negative bacteria, leaving them colorless, while gram-positive bacteria retain the stain due to their thicker peptidoglycan layer.

Question 6

The specimens are Gram-stained and analyzed microscopically. The laboratory technician observes spherical purple cells arranged in short chains. Based upon this evidence, which of the following microbes is potentially the pathogen affecting the patient?

Accepted Answer

Streptococcus pneumoniae typically appears as spherical purple cells arranged in short chains under the microscope and is a common pathogen causing respiratory tract infections. Bacillus cereus is a rod-shaped bacterium and appears as a chain, Vibrio cholerae is a curved rod-shaped bacterium, and Staphylococcus aureus appears in clusters.

Question 7

The RN provides education for the family about the laboratory findings. Which of the following statements correctly describes the medical importance of a bacterial capsule?

Accepted Answer

A bacterial capsule is an outer layer surrounding some bacteria that can protect them from being engulfed and destroyed by white blood cells, making it easier for the bacterium to cause disease.

Question 8

The laboratory report shows that a motility test was performed on the sample with positive results. Thinking about bacterial movement, the RN is aware that this bacterium could possess which structure(s) for motility?

Accepted Answer

Motility tests are used to identify bacteria with the ability to move. The most common structure used by bacteria for motility is the flagella. Flagella are long, whip-like structures that are used to propel the bacteria forward. Endospores are not involved in motility, they are structures that form when bacteria are under stress. Pili are used for attachment and exchange of genetic material, not for motility. Pseudopodia are structures used by some eukaryotic cells, such as amoebas, for movement, but not by bacteria.

Question 9

The provider educates the patient about his condition, based on information from the laboratory findings and clinical presentation. Later, the RN reinforces the teaching and explains why this infection may be difficult to treat with antibiotics. Which part of the cell envelope restricts the passage of many of drugs into gram-negative bacteria?

Accepted Answer

The outer membrane layer of gram-negative bacteria restricts the passage of many drugs into the cell. The other choices are also components of the gram-negative cell envelope, but they are not responsible for drug resistance.

Question 10

Specimen collection from the patient is ordered for microbial analysis in the hospital laboratory. Based upon the patient's symptoms, which of the following samples would the RN expect to be ordered for collection?

Accepted Answer

Based on the patient's symptoms of bloody diarrhea and stomach cramps, a stool sample would be the most appropriate specimen for microbial analysis to identify the source of infection. The other options, such as cerebrospinal fluid, clean catch urine, and aseptic collection of sputum, are not relevant to the patient's symptoms.

Question 11

Further microscopic analysis of negatively stained specimens reveals a colorless ring around each of the spherical cells against a dark background. This clearing indicates that the pathogen possesses which structure(s)?

Accepted Answer

The colorless ring around each of the spherical cells indicates the presence of a capsule, which can be seen as a cleared-out area around the bacterial cell in a negative stain. Endospores are typically non-liquefied, refractile structures that are best visualized using a spore stain. A nucleoid would be located inside the bacterial cell and would not be visible with a negative stain. Pili are thin, hair-like structures that may be visible on the surface of the cell but would not produce a clearing effect in a negative stain.

Question 12

Microscopic analysis revealed the presence of gram-negative bacilli in the patient's stool. Based upon this information, which of the following accurately describes the appearance of the bacterium under magnification?

Accepted Answer

Gram-negative bacilli appear as red rods under microscopic analysis after Gram staining due to their cell wall composition, which does not retain the crystal violet stain but takes up the counterstain (safranin or fuchsine), appearing red.

Question 13

Gram staining reveals the presence of gram-negative bacilli in the patient's stool. The RN understands how this bacterium would cause the patient's spike in temperature. Which of the following is the correct explanation for this patient's fever?

Accepted Answer

Gram-negative bacteria have lipopolysaccharide (LPS) in their outer membrane, and the lipid portion, known as endotoxin, is responsible for causing fever. LPS stimulates the immune system to release cytokines, which in turn raise the body temperature.

Quiz 3: Bacteria and Archaea