Nokea
Decontamination is defined as the
- A. killing of all microorganisms in a given area.
- B. reduction or removal of unwanted chemical or biological agents.
- C. stopping of the growth of microorganisms in a given area.
- D. removal of all vegetative organisms.
Correct Answer: B
Rationale: Decontamination is the reduction or removal of unwanted chemical or biological agents to make an area safe. This includes cleaning, disinfecting, or sterilizing to eliminate harmful substances. Choice A is incorrect as decontamination doesn't necessarily involve killing all microorganisms. Choice C is incorrect as it focuses on stopping growth, not removing existing contaminants. Choice D is incorrect as it specifically mentions vegetative organisms, which may not cover all types of contaminants that need to be removed during decontamination. Thus, the correct answer is B as it accurately describes the process of decontamination.
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Choose which one fo the following microorganisms is an example of obligate parasitism
- A. HIV
- B. E. Coli
- C. S. Epidermidis
- D. Pseudomonas aeruginosa
Correct Answer: A
Rationale: The correct answer is A: HIV. HIV is an example of obligate parasitism because it requires a host cell to replicate and survive. It cannot live independently outside of a host organism. In contrast, choices B, C, and D are not obligate parasites. E. Coli and S. Epidermidis are examples of commensal bacteria that can live in the host without causing harm. Pseudomonas aeruginosa can be both an opportunistic pathogen and a free-living organism, not strictly dependent on a host for survival.
A patient's blood culture revealed Gram-positive rods capable of spore formation. They were also motile and produced gas in nutrient broth. What is the causative agent?
- A. Clostridium perfringens
- B. Bacillus anthracis
- C. Clostridium tetani
- D. Bacillus cereus
Correct Answer: A
Rationale: The correct answer is A: Clostridium perfringens. This bacterium fits all the characteristics mentioned: Gram-positive rods with spore formation, motile, and gas production in nutrient broth. Clostridium perfringens is known to cause gas gangrene, which aligns with the gas production in nutrient broth. Bacillus anthracis (B) causes anthrax and does not typically produce gas. Clostridium tetani (C) causes tetanus and does not form spores that are motile. Bacillus cereus (D) is a common cause of food poisoning and does not cause gas gangrene.
The number of new cases of a disease over a certain period of time compared with the general healthy population is referred to as:
- A. incidence
- B. prevalence
- C. virulence
- D. mortality
Correct Answer: A
Rationale: The correct answer is A: incidence. Incidence refers to the number of new cases of a disease occurring within a specific time period in relation to the healthy population. It helps in understanding the risk of developing the disease. Prevalence (B) is the total number of existing cases at a given point in time. Virulence (C) is the severity of the disease once contracted. Mortality (D) refers to the number of deaths due to the disease, not the new cases. Therefore, the correct term for new cases is incidence.
In which of the following GIT infections, the bacteria adhere to the intestine wall and produce toxins:
- A. Shigella spp.
- B. Enteropathogenic E.coli (EPEC)
- C. Salmonella spp.
- D. Vibrio cholerae
Correct Answer: B
Rationale: Rationale:
1. Enteropathogenic E.coli (EPEC) adheres to the intestinal wall using bundle-forming pili.
2. EPEC produces toxins that disrupt cell structure and function, leading to diarrhea.
3. Shigella spp. invade intestinal cells, Salmonella spp. invade and multiply within cells, and Vibrio cholerae produces cholera toxin causing profuse watery diarrhea.
Summary:
A, C, and D choices are incorrect because they do not specifically adhere to the intestine wall and produce toxins like EPEC does.
Which of the following sites of the human body does not have a normal flora?
- A. Intestine
- B. Skin
- C. Vagina
- D. Blood
Correct Answer: D
Rationale: The correct answer is D: Blood. Normal flora refers to the microorganisms that naturally inhabit specific areas of the body. Blood is considered a sterile environment in healthy individuals, meaning it does not harbor any microorganisms under normal circumstances. In contrast, the intestine, skin, and vagina all have normal flora as they provide suitable environments for various microbial species to thrive. The presence of normal flora in these sites helps maintain a balance and protect against pathogenic invaders. Blood, being a vital and sterile fluid, is not meant to have any resident microbial populations.