A hospitalized patient with antibiotic-associated diarrhea has stool cultures showing spore-forming rods with a thick cell wall. What Gram-stain color would be observed?
Gram-negative
Gram-positive
The Correct Answer is B
Spore-forming rods with a thick cell wall, such as Clostridioides difficile, are classified as gram-positive bacteria. Their thick peptidoglycan layer retains the crystal violet stain during the Gram-staining process, causing them to appear purple under a microscope. The spore-forming ability allows these bacteria to survive harsh conditions, including exposure to antibiotics, which can disrupt normal gut flora. The combination of thick peptidoglycan and spore formation is characteristic of gram-positive bacilli. Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane containing lipopolysaccharides. They do not retain the crystal violet stain and instead appear pink after counterstaining with safranin. Spore formation is not a typical feature of gram-negative organisms.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Eukaryotic cells are characterized by having a true nucleus, which houses the cell’s genetic material enclosed within a nuclear membrane. In addition, they contain various membrane-bound organelles, such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and peroxisomes, each performing specialized cellular functions. This organization allows compartmentalization of metabolic processes, efficient energy production, and regulated protein synthesis. In contrast, prokaryotic cells lack a nucleus and membrane-bound organelles, with DNA located in a nucleoid region. The presence of these features distinguishes eukaryotes from prokaryotes and is fundamental to understanding their structural and functional complexity.
Correct Answer is A
Explanation
A. Cocci, bacilli, coccobacilli, vibrios, spirilla, and spirochetes: These are all recognized bacterial shapes. Cocci are spherical, bacilli are rod-shaped, coccobacilli are short rods, vibrios are comma-shaped, spirilla are rigid spiral-shaped bacteria, and spirochetes are flexible, corkscrew-shaped bacteria. These morphological classifications are used in microbiology to identify and categorize bacterial species.
B. Cocci, diplocytes, flagella, fimbriae, and spores: While cocci are a bacterial shape, diplocytes refers to paired cocci, flagella and fimbriae are appendages, and spores are dormant survival structures. This list mixes shapes with structures, hence does not exclusively describe bacterial morphology.
C. Bacilli, nuclei, ribosomes, mitochondria, and cocci: Bacilli and cocci are bacterial shapes, but nuclei, ribosomes, and mitochondria are cellular organelles not used to define bacterial morphology. Bacteria are prokaryotes and lack membrane-bound organelles.
D. Spirilla, cilia, capsules, and peptidoglycan: Spirilla is a bacterial shape, but cilia are eukaryotic structures, capsules are extracellular protective layers, and peptidoglycan is a cell wall component. Only spirilla refers to bacterial morphology.
E. Spirochetes, lysosomes, peroxisomes, and cocci: Spirochetes and cocci are bacterial shapes, but lysosomes and peroxisomes are eukaryotic organelles. This list is not limited to recognized bacterial morphologies.
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