Which of the following pathogens has the widest infectious spectrum

Correct Answer: A

Rationale: The correct answer is A, Anthrax bacillus, because it has the widest infectious spectrum among the options provided. Anthrax bacillus can infect a wide range of hosts, including humans and various animals. It is known for its ability to survive in different environments and cause disease through various routes of exposure. In contrast, choices B, C, and D have more limited infectious spectra. Mumps virus primarily infects humans, the causative agent of gonorrhea mainly affects humans through sexual contact, and the rabies virus typically infects mammals through bites from infected animals. Therefore, Anthrax bacillus is the correct choice due to its broader range of hosts and modes of transmission compared to the other options.

Correct Answer: C

Rationale: Rationale for choice C (Adenovirus) being correct: 1. Adenovirus is a common cause of acute hemorrhagic cystitis. 2. Adenovirus infects the bladder epithelium, leading to inflammation and bleeding. 3. Symptoms include hematuria and bladder pain. 4. Diagnosis is confirmed through viral culture or PCR testing. Summary of why other choices are incorrect: A: Parvovirus B19 - More commonly associated with erythema infectiosum (fifth disease) and aplastic anemia. B: CMV - Known to cause congenital infections, mononucleosis, and retinitis, not typically associated with hemorrhagic cystitis. D: Herpesvirus type 2 - Commonly causes genital herpes, but not typically associated with acute hemorrhagic cystitis.

Correct Answer: C

Rationale: The correct answer is C: Transcription. Transcription is the process of synthesizing RNA from a DNA template. During transcription, RNA polymerase binds to the DNA and produces a complementary RNA strand. This process is essential for gene expression. Explanation for why other choices are incorrect: A: Transposition involves the movement of genetic elements within a genome, not the production of RNA from DNA. B: Translation is the process of synthesizing proteins from mRNA, not the production of RNA from DNA. D: RNA splicing is the process of removing introns and joining exons in pre-mRNA to produce mature mRNA, not the initial production of RNA from DNA.

Correct Answer: C

Rationale: The correct answer is C: Kirby-Bauer disk diffusion test. This test is used to determine the antibiotic susceptibility of bacteria by measuring the zone of inhibition around antibiotic-soaked paper disks. It helps identify which antibiotics are effective against the bacteria being tested. This test is crucial in guiding antibiotic treatment decisions. A: Gram stain is used to classify bacteria based on their cell wall composition and morphology, not for antibiotic susceptibility testing. B: Catalase test is used to differentiate between catalase-positive and catalase-negative bacteria, not for antibiotic susceptibility testing. D: Endospore stain is used to detect the presence of endospores in bacteria, not for antibiotic susceptibility testing.

Correct Answer: B

Rationale: The correct answer is B: Outer membrane with lipopolysaccharides. Gram-negative bacteria have an outer membrane containing lipopolysaccharides (LPS), which are important in pathogenesis and immune response. This feature is unique to Gram-negative bacteria, distinguishing them from Gram-positive bacteria (choice A). Teichoic acids (choice C) are found in the cell walls of Gram-positive bacteria, not Gram-negative. The statement in choice D, absence of a cell wall, is incorrect as all bacteria have a cell wall, although the composition may vary between Gram-negative and Gram-positive bacteria.

Correct Answer: A

Rationale: The correct answer is A: TRUE. Poxviruses are indeed the largest viruses, ranging from 200-450 nm in size, which is close to the resolution limit of a light microscope. This makes them almost visible under a light microscope. The other choices are incorrect because poxviruses are not smaller or uncertain in size (choices B and C), nor are they partially visible - they are almost visible due to their relatively large size.

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known for producing a blue-green pigment called pyocyanin, which gives the characteristic color seen in the wound abscess. The distinctive odor of jasmine is also a key feature of Pseudomonas aeruginosa. Proteus vulgaris (B) and Klebsiella pneumoniae (D) do not produce blue-green pigment or have a jasmine-like odor. Escherichia coli (C) typically does not produce blue-green pigment or have a jasmine-like odor.

Correct Answer: D

Rationale: The correct answer is D: All of the above. - Streptococcus pneumoniae is a common cause of community-acquired pneumonia. - Mycobacterium tuberculosis can cause pulmonary tuberculosis, which can present as pneumonia-like symptoms. - Pseudomonas aeruginosa is an opportunistic pathogen that can cause pneumonia in immunocompromised individuals. Therefore, all three bacteria can cause pneumonia, making option D the correct choice. Options A, B, and C are incorrect because they each represent a bacterium that can cause pneumonia, so only selecting one of them would not encompass all common causes of pneumonia.

Correct Answer: A

Rationale: The correct answer is A: Entamoeba histolytica. This protozoan causes amoebiasis, which presents with symptoms like diarrhea. The cysts with four nuclei found in the feces are characteristic of Entamoeba histolytica. This protozoan is known to cause invasive infection, leading to tissue destruction and ulcers in the intestines. Lamblia (choice B) typically presents with cysts containing two nuclei. Trichomonas (choice C) is a sexually transmitted parasite and does not form cysts. Balantidium (choice D) is a ciliated protozoan that does not have four nuclei in its cyst form.