Infections that may result from the use of catheters are classified as:

Correct Answer: A

Rationale: The correct answer is A: iatrogenic infections. Iatrogenic infections are those caused by medical interventions like catheter use. Catheters can introduce pathogens into the body, leading to infections. Local infections (B) refer to infections confined to a specific area, not necessarily caused by catheters. Exogenous infections (C) come from an external source, not specifically related to medical interventions. Endogenous infections (D) arise from the body's own flora and are not directly related to catheter use.

Correct Answer: B

Rationale: Step 1: The description of microorganisms resembling tennis racket indicates Corynebacterium diphtheriae, the causative agent of diphtheria. Step 2: Diphtheria is a bacterial infection that can cause severe respiratory and systemic symptoms. Step 3: Botulism is caused by Clostridium botulinum, not tennis racket-shaped microorganisms. Step 4: Typhoid fever is caused by Salmonella typhi, which does not resemble tennis rackets. Step 5: Salmonellosis is caused by various Salmonella species, which also do not have the described tennis racket appearance.

Correct Answer: B

Rationale: The correct answer is B: BCG vaccine. Bacille Calmette-Guérin (BCG) vaccine is used to prevent tuberculosis, which is caused by a bacterium related to anthrax. BCG vaccine can provide cross-protection against anthrax due to its similar mechanisms of action. STI live vaccine (choice A) is used for sexually transmitted infections, not anthrax. Salk vaccine (choice C) is used for polio, and Sabin's vaccine (choice D) is also for polio, not anthrax. Therefore, BCG vaccine is the most appropriate choice for preventing the spread of anthrax among animals in the countryside.

Correct Answer: A

Rationale: The correct answer is A: Acid resistance. Tuberculosis mycobacteria have a unique cell wall structure that makes them resistant to acid-fast staining methods like Ziehl-Neelsen. This is due to the high lipid content of their cell walls, specifically mycolic acids, which prevent the penetration of stains and acids. The red bacilli observed in the smear indicate that the mycobacteria retained the primary stain (carbolfuchsin) after acid-alcohol decolorization, confirming their acid resistance. Summary: - Choice A: Acid resistance is correct due to the unique cell wall structure of tuberculosis mycobacteria. - Choice B: Alkali resistance is incorrect as mycobacteria are not known for being resistant to alkalis. - Choice C: Alcohol resistance is incorrect as mycobacteria are not specifically resistant to alcohols. - Choice D: Encapsulation is incorrect as mycobacteria are not encapsulated bacteria.

Correct Answer: C

Rationale: The correct answer is C: Epidemic. This term refers to the widespread occurrence of an infectious disease in a specific community or region at a particular time. In this scenario, the infection of many people with a known epidemiological link indicates a localized outbreak within a defined population. Explanation: 1. Epidemic specifically refers to a sudden increase in the number of cases of a disease above what is normally expected in a population. 2. The term "known epidemiological link" suggests a clear connection between the cases, indicating a common source or mode of transmission within a specific group. 3. Endemic (choice A) refers to the constant presence of a disease within a specific geographic area or population. 4. Pandemic (choice B) refers to a global outbreak of a disease that spreads across countries and continents. 5. Sporadic disease (choice D) refers to isolated cases that occur infrequently and without a clear pattern. In summary, an epidemic best describes the situation of many people being

Correct Answer: A

Rationale: The correct answer is A: A vaccine strain. Virus Fixe is a specific strain of rabies virus used in the production of rabies vaccines. This strain has been attenuated to be safe for use in vaccines. Choice B, a cell culture, is incorrect as it does not specifically refer to Virus Fixe. Choice C, a wild type of rabies virus, is incorrect as Virus Fixe is not a wild type but a modified strain. Choice D, an infectious disease, is incorrect as Virus Fixe is not a disease but a strain of virus used in vaccines.

Correct Answer: A

Rationale: The correct answer is A: Absence of a cell wall. L-form transformation is a phenomenon where the pathogen loses its cell wall, making it resistant to antibiotics like penicillin. The absence of a cell wall allows the pathogen to survive in a hostile environment. Choice B: Absence of flagella is incorrect because flagella are responsible for motility and not directly related to L-form transformation. Choice C: Absence of a capsule is incorrect as the capsule is a protective layer outside the cell wall and not affected by L-form transformation. Choice D: Absence of a spore is incorrect because spores are a dormant form of bacteria and not related to L-form transformation.

Correct Answer: A

Rationale: Step 1: Understand haematogenic spread means bacteria traveling through blood. Step 2: Urinary tract infections typically occur due to bacteria entering through urethra, not via blood. Step 3: Choice A states bacterial UTIs are usually after haematogenic spread, which is incorrect. Step 4: Therefore, Choice A is NOT true for UTIs. Summary: B, C, and D are incorrect as they align with typical characteristics of UTIs.

Correct Answer: B

Rationale: The correct answer is B: psittacosis. Psittacosis is an infection caused by Chlamydia psittaci that primarily affects the lower respiratory tract, leading to pneumonia-like symptoms. Mycoplasma pneumoniae causes atypical pneumonia, not pharyngitis (Choice A). Chronic atrophic rhinitis (Choice C) and rhinoscleroma (Choice D) both affect the upper respiratory tract, not the lower respiratory tract. Psittacosis specifically targets the lower respiratory tract, making it the most appropriate answer.