Microbiology Study Questions

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  • 1/223 Questions

    Growth factors X and V are essential in the cultivation of:

    • Haemophilus species
    • Bordetella species
    • Pasteurella species
    • Staphylococcus species
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About This Quiz

The 'Microbiology Study Questions' quiz assesses knowledge on protozoa classification, parasite locomotion, and specimen analysis. It covers practical skills for identifying parasites in feces and urine, crucial for learners in healthcare and laboratory sciences.

Microbiology Study Questions - Quiz

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  • 2. 

    The scientific name for the organism that causes syphilis is:

    • Leptospira interrogans

    • Treponema pallidum

    • Treponema carateum

    • Borrelia vicentii

    Correct Answer
    A. Treponema pallidum
    Explanation
    Treponema pallidum is the correct answer for the scientific name of the organism that causes syphilis. This bacterium is a spirochete and is responsible for causing the sexually transmitted infection known as syphilis. It is a highly contagious and sexually transmitted disease that can have serious consequences if left untreated. Treponema pallidum is a spiral-shaped bacterium that can invade various tissues and organs in the body, leading to a wide range of symptoms and complications.

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  • 3. 

    Pinworm is the common name for:

    • Toxocara canis

    • Enterobius vermicularis

    • Fasciola hepatica

    • Fasciolopsis buski

    Correct Answer
    A. Enterobius vermicularis
    Explanation
    Enterobius vermicularis is the correct answer because it is the scientific name for pinworm, a common parasitic worm that infects the intestines of humans. Toxocara canis is the scientific name for a roundworm that infects dogs, not humans. Fasciola hepatica is the scientific name for a liver fluke that infects sheep and other animals, while Fasciolopsis buski is the scientific name for a large intestinal fluke that infects humans and pigs. Therefore, only Enterobius vermicularis corresponds to the common name "pinworm".

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  • 4. 

    Acid-fast bacteria belong to which of the following genera:

    • Mycobacterium

    • Listeria

    • Corynebacterium

    • Clostridium

    Correct Answer
    A. Mycobacterium
    Explanation
    Acid-fast bacteria belong to the genus Mycobacterium. This genus includes bacteria such as Mycobacterium tuberculosis, which causes tuberculosis, and Mycobacterium leprae, which causes leprosy. Acid-fast bacteria have a unique cell wall structure that allows them to retain a stain even when treated with acid alcohol. This property is useful in their identification and is a characteristic feature of Mycobacterium species.

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  • 5. 

    The process by which organisms adhere to a slide is called:

    • Fixation

    • Coagulation

    • Denaturation

    • Proteinization

    Correct Answer
    A. Fixation
    Explanation
    Fixation is the correct answer because it refers to the process by which organisms are attached or adhered to a slide, typically through the use of chemicals or heat. This process helps to preserve the structure and integrity of the organisms for further examination and analysis under a microscope. Coagulation, denaturation, and proteinization do not specifically refer to the process of organisms adhering to a slide.

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  • 6. 

    The genus that shows characteristic "swarming" on agar media is:

    • Pseudomonas

    • Proteus

    • Pasteurella

    • Klebsiella

    Correct Answer
    A. Proteus
    Explanation
    Proteus is the correct answer because it is a genus of bacteria that exhibits a unique characteristic called "swarming" on agar media. Swarming refers to the rapid and coordinated movement of bacteria across a solid surface, such as agar, facilitated by the production of flagella. This allows the bacteria to spread and colonize new areas efficiently. Pseudomonas, Pasteurella, and Klebsiella are not known to exhibit swarming behavior, making Proteus the most suitable choice.

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  • 7. 

    Entamoeba histolytica is classified as a/an:

    • Amoeba

    • Flagellate

    • Ciliate

    • Sporozoa

    Correct Answer
    A. Amoeba
    Explanation
    Entamoeba histolytica is classified as an amoeba because it belongs to the phylum Amoebozoa, which includes amoebas. Amoebas are single-celled organisms that move and feed by extending pseudopods, which are temporary projections of the cell membrane. Entamoeba histolytica is a parasitic amoeba that can cause amoebic dysentery, a severe intestinal infection. Its classification as an amoeba is based on its morphological characteristics and its mode of movement.

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  • 8. 

    Of the following body sites, the only one to have a normal flora is the:

    • Urinary bladder

    • Vagina

    • Kidney

    • Ureter

    Correct Answer
    A. Vagina
    Explanation
    The vagina is the only body site listed that has a normal flora. Normal flora refers to the microorganisms that naturally reside in and on the human body without causing harm. The vagina has a unique ecosystem, known as the vaginal microbiota, which consists of various bacteria, fungi, and other microorganisms. These microorganisms play a crucial role in maintaining a healthy vaginal environment by preventing the overgrowth of harmful bacteria and maintaining the pH balance. The urinary bladder, kidney, and ureter typically do not have a normal flora as they are considered sterile environments.

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  • 9. 

    An organism from a burn patient produced a diffusible green pigment on Mueller-Hinton sensitivity test agar; it was oxidase positive and resistant to many antibiotics. Its identity is most likely:

    • Stenotrophomonas maltophilia

    • Acinetobacter calcoaceticus, Var. anitratus

    • Pseudomonas aeruginosa

    Correct Answer
    A. Pseudomonas aeruginosa
    Explanation
    Pseudomonas aeruginosa is the most likely identity of the organism because it exhibits several characteristic features. The production of a diffusible green pigment on Mueller-Hinton sensitivity test agar is a classic trait of Pseudomonas aeruginosa. Additionally, being oxidase positive and resistant to many antibiotics are also common characteristics of this bacterium. Stenotrophomonas maltophilia and Acinetobacter calcoaceticus, Var. anitratus may have some similar features but they do not exhibit the specific combination of traits seen in Pseudomonas aeruginosa.

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  • 10. 

    The majority of bacteria will grow within a temperature range of:

    • 2-6 degrees C

    • 15-43 degrees C

    • 50-60 degrees C

    • 98-100 degrees C

    Correct Answer
    A. 15-43 degrees C
    Explanation
    Bacteria are known to thrive in a variety of environments, and their growth is influenced by temperature. The temperature range of 15-43 degrees Celsius is considered optimal for the majority of bacteria to grow. At temperatures below 15 degrees Celsius, bacterial growth slows down, while temperatures above 43 degrees Celsius can inhibit or kill bacteria. Therefore, the range of 15-43 degrees Celsius provides the most conducive conditions for bacterial growth and reproduction.

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  • 11. 

    The Kinyoun cabolfuchsin method is used to stain:

    • Gram positive bacteria

    • Gram negative bacteria

    • Acid-fast bacilli

    • None of these

    Correct Answer
    A. Acid-fast bacilli
    Explanation
    The Kinyoun carbolfuchsin method is specifically used to stain acid-fast bacilli. Acid-fast bacilli are a group of bacteria that have a unique cell wall structure, which makes them resistant to standard staining methods like the Gram stain. The Kinyoun method involves using a strong red dye called carbolfuchsin, along with heat and an acid-alcohol decolorizer, to penetrate the tough cell wall of acid-fast bacilli and stain them red. This staining technique is commonly used in the diagnosis of tuberculosis and other diseases caused by acid-fast bacilli.

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  • 12. 

    Whooping cough is confimed by the isolation of:

    • Bordetella pertussis

    • Corynebacterium diphtheriae

    • Hemophilus influenzae

    • Beta hemolytic Streptococcus

    Correct Answer
    A. Bordetella pertussis
    Explanation
    Whooping cough, also known as pertussis, is caused by the bacterium Bordetella pertussis. The isolation of Bordetella pertussis confirms the presence of whooping cough. Corynebacterium diphtheriae causes diphtheria, Hemophilus influenzae causes various infections including pneumonia, and Beta hemolytic Streptococcus causes strep throat and other infections. However, in the context of whooping cough, the correct answer is Bordetella pertussis.

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  • 13. 

    Normally, the bloodstream:

    • Contains a variety of organisms

    • Has only gram-positive organisms circulating

    • Has only gram-negative organisms circulating

    • Has no organisms circulating

    Correct Answer
    A. Has no organisms circulating
    Explanation
    The bloodstream is normally a sterile environment, meaning it does not contain any microorganisms or organisms circulating. This is because the body has various defense mechanisms, such as the immune system and the physical barriers of blood vessels, to prevent the entry and circulation of organisms in the bloodstream. Any presence of organisms in the bloodstream can indicate an infection or an abnormal condition.

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  • 14. 

    Motile bacteria always possess:

    • Capsules

    • Flagella

    • Metachromatic granules

    • Spores

    Correct Answer
    A. Flagella
    Explanation
    Motile bacteria are able to move and propel themselves in their environment. One of the main structures responsible for their movement is flagella. Flagella are long, whip-like appendages that extend from the surface of the bacteria and enable them to swim or move in a directed manner. Capsules, metachromatic granules, and spores are not directly related to the motility of bacteria.

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  • 15. 

    Only one amoeba is considered to be definitely pathogenic to man. It is:

    • Entamoeba histolytica

    • Entamoeba coli

    • Dientamoeba fragilis

    • Endolimax nana

    Correct Answer
    A. Entamoeba histolytica
    Explanation
    Entamoeba histolytica is the only amoeba that is known to be definitely pathogenic to humans. This means that it is capable of causing disease in humans. The other three amoebas listed, Entamoeba coli, Dientamoeba fragilis, and Endolimax nana, are not considered to be pathogenic to humans. They may be present in the human digestive system, but they do not typically cause disease or harm to the host. Therefore, the correct answer is Entamoeba histolytica.

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  • 16. 

    One of the ways antibiotics work against pathogens is to:

    • Inhibit flagella

    • Enhance conjugation

    • Inhibit protein synthesis

    • Rearrange the cytoplasm

    • Destroy cilia

    Correct Answer
    A. Inhibit protein synthesis
    Explanation
    Antibiotics work by inhibiting protein synthesis in pathogens. This means that they interfere with the ability of the pathogen to produce proteins necessary for its survival and reproduction. By targeting the pathogen's protein synthesis machinery, antibiotics can effectively kill or inhibit the growth of the pathogen, helping to treat infections. This mechanism of action is one of the key ways antibiotics exert their antimicrobial effects.

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  • 17. 

    The family, Enterobacteriaceae:

    • Is made up of gram-negative bacilli that inhibit the intestinal tract of man.

    • Contains the microorganisms that cause undulant fever

    • Contains members that cause meningitis and gonorrhea

    • Contains all the gram-positive cocci

    Correct Answer
    A. Is made up of gram-negative bacilli that inhibit the intestinal tract of man.
    Explanation
    The correct answer is "Is made up of gram-negative bacilli that inhibit the intestinal tract of man." This answer accurately describes the family Enterobacteriaceae. Enterobacteriaceae is a family of bacteria that are gram-negative, meaning they do not retain the purple stain in the Gram staining method. These bacteria are commonly found in the intestinal tract of humans and animals. They can cause various infections, including urinary tract infections, respiratory infections, and gastrointestinal infections. Therefore, the statement that Enterobacteriaceae is made up of gram-negative bacilli that inhibit the intestinal tract of man is correct.

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  • 18. 

    If when doing a urine culture, you find 146 colonies on the agar plate media, how many organisms are present per ml or urine?

    • 14600/ml

    • 14000/ml

    • 146000/ml

    • 2910000/ml

    Correct Answer
    A. 146000/ml
    Explanation
    The correct answer is 146000/ml. This is because the question asks for the number of organisms present per ml of urine, and the given information states that there are 146 colonies on the agar plate media. Therefore, the number of organisms per ml of urine would be 146000.

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  • 19. 

    Pseudomonas aeruginosa is probably test identified by its characteristic:

    • Golden yellow pigment

    • Green pigment

    • Red pigment

    • Lack of pigment

    Correct Answer
    A. Green pigment
    Explanation
    Pseudomonas aeruginosa is probably best identified by its characteristic green pigment. This pigment, called pyocyanin, is produced by the bacterium and gives it a distinct green color. This characteristic can be used to differentiate Pseudomonas aeruginosa from other bacteria that may have different pigments or lack pigmentation altogether.

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  • 20. 

    Biochemically, a stool culture isolate appears to be a Salmonella sp, but it fails to agglutinate with Salmonella antisera. Therefore, one should:

    • Heat a suspension for 15-30 minutes, cool and re-test with the same antisera

    • Repeat the biochemical tests

    • Send out a report, "Negative for Salmonella"

    Correct Answer
    A. Heat a suspension for 15-30 minutes, cool and re-test with the same antisera
    Explanation
    The correct answer is to heat a suspension for 15-30 minutes, cool, and re-test with the same antisera. This is because heating the suspension can help to remove any inhibitory substances that may be preventing the agglutination reaction. By re-testing with the same antisera, it allows for a second chance to detect any agglutination that may have been initially missed.

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  • 21. 

    Microogranisms that are difficult to grow and may require special media are termed:

    • Gram positive

    • Gram negative

    • Fastidious

    • Coliforms

    Correct Answer
    A. Fastidious
    Explanation
    Fastidious microorganisms are those that have specific nutritional requirements and are difficult to grow in standard laboratory media. They may require special media or specific growth conditions to support their growth. This term is used to describe microorganisms that are more demanding in terms of their nutritional needs and are therefore more challenging to cultivate in the laboratory.

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  • 22. 

    The triple sugar iron agar is valuable because it yields information about:

    • Carbohydrate fermentation

    • Production of gas

    • Production of hydrogen sulfaide

    • All of these

    Correct Answer
    A. All of these
    Explanation
    The triple sugar iron agar is valuable because it can provide information about multiple aspects such as carbohydrate fermentation, production of gas, and production of hydrogen sulfide. By observing the reactions of bacteria on this agar, we can determine if they are able to ferment different sugars, produce gas, and generate hydrogen sulfide. This information is crucial in identifying and classifying different bacterial species based on their metabolic capabilities.

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  • 23. 

    The special media used in the diagnosis of whooping cough is:

    • Sheep blood agar

    • Phenylethyl alcohol

    • Bordet-gengou

    • Eosin methylene blue

    Correct Answer
    A. Bordet-gengou
    Explanation
    Bordet-Gengou agar is a special media used in the diagnosis of whooping cough, also known as pertussis. This media is selective for the growth of Bordetella pertussis, the bacteria responsible for causing whooping cough. It contains specific nutrients and inhibitors that promote the growth of Bordetella pertussis while inhibiting the growth of other bacteria. By inoculating patient samples onto Bordet-Gengou agar and observing for characteristic colony morphology, healthcare professionals can confirm the presence of Bordetella pertussis and make a definitive diagnosis of whooping cough.

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  • 24. 

    The genus of parasites which causes malaria is:

    • Leishmania

    • Toxoplasma

    • Trypanosoma

    • Plasmodium

    Correct Answer
    A. Plasmodium
    Explanation
    Plasmodium is the correct answer because it is the genus of parasites that causes malaria. Malaria is a mosquito-borne infectious disease that affects humans and other animals. Plasmodium parasites are transmitted through the bite of infected female Anopheles mosquitoes. Once inside the human body, the parasites multiply in the liver and then infect red blood cells, causing the symptoms of malaria. Therefore, Plasmodium is the genus responsible for causing this disease.

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  • 25. 

    On MacConkey's agar, Klebsiella is:

    • Colorless

    • Coloress with dark centers

    • Pink, mucoid

    • Salmon colored

    Correct Answer
    A. Pink, mucoid
    Explanation
    On MacConkey's agar, Klebsiella appears as pink, mucoid colonies. MacConkey's agar is a selective and differential medium used to isolate and differentiate gram-negative bacteria, particularly members of the Enterobacteriaceae family. It contains lactose and a pH indicator that turns pink when lactose is fermented. Klebsiella is a lactose-fermenting bacterium, so it produces acid during fermentation, causing the colonies to turn pink. Additionally, Klebsiella often produces a sticky, mucoid capsule, which gives the colonies a mucoid appearance. Therefore, the correct answer is pink, mucoid.

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  • 26. 

    Darkfield microscopy is commonly used to visualize:

    • Pseudomonas aeruginosa

    • Streptococcus pneumoniae

    • Treponema pallidum

    • Legionella pneumophila

    Correct Answer
    A. Treponema pallidum
    Explanation
    Darkfield microscopy is commonly used to visualize Treponema pallidum. Darkfield microscopy is a technique in which the specimen is illuminated with a hollow cone of light, causing the organisms to appear bright against a dark background. Treponema pallidum is the bacterium that causes syphilis, and it is difficult to visualize using other microscopy techniques due to its thin, spiral shape and low contrast against the background. Darkfield microscopy allows for better visualization of Treponema pallidum, making it a valuable tool in diagnosing syphilis.

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  • 27. 

    Mueller-Hinton agar:

    • Is used in all bacterial cultivation media as a base

    • Is used n the agar-disk diffusion method of testing for antibiotic susceptibility of microorganism

    • Is a good differential media

    • Inhibit gram positive growth

    Correct Answer
    A. Is used n the agar-disk diffusion method of testing for antibiotic susceptibility of microorganism
    Explanation
    Mueller-Hinton agar is used in the agar-disk diffusion method of testing for antibiotic susceptibility of microorganisms. This method involves placing antibiotic disks on the agar surface and measuring the zone of inhibition to determine the effectiveness of the antibiotic against the microorganism. Mueller-Hinton agar provides a standardized and consistent medium for this testing method, allowing for accurate and reliable results.

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  • 28. 

    Which parasite is sometimes found in the microscopic examination of urine?

    • Plasmodium

    • Tapeworm segments

    • Trichomonas

    • Yeast

    Correct Answer
    A. Trichomonas
    Explanation
    Trichomonas is a parasite that can be found in the microscopic examination of urine. It is a single-celled organism that infects the urinary tract and can cause symptoms such as itching, burning, and discharge. The presence of Trichomonas in urine can be detected through laboratory testing, where the urine sample is examined under a microscope to identify the parasite's characteristic appearance. This finding can help diagnose a Trichomonas infection and guide appropriate treatment. Plasmodium is a parasite that causes malaria and is not typically found in urine. Tapeworm segments and yeast are also not commonly seen in urine samples.

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  • 29. 

    Sabouraud's agar is used to:

    • Culture animal parasites

    • Grow fungi and inhibit bacterial growth

    • Grow bacteria and inhibit fungi

    • Grow both bacteria and fungi

    Correct Answer
    A. Grow fungi and inhibit bacterial growth
    Explanation
    Sabouraud's agar is a specialized culture medium used in microbiology to grow fungi. It contains a lower pH and higher sugar concentration, creating an environment that is favorable for fungal growth while inhibiting the growth of bacteria. This selective medium helps to isolate and identify different types of fungi.

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  • 30. 

    A good method of identifying Cryptococcus neoformans is the:

    • India ink stain

    • Gram stain

    • Acid-fast stain

    • Methylene blue stain

    Correct Answer
    A. India ink stain
    Explanation
    The India ink stain is a good method of identifying Cryptococcus neoformans because it allows for the visualization of the characteristic capsule that surrounds the yeast cells. This capsule appears as a clear halo around the stained cells, making it easier to distinguish Cryptococcus neoformans from other microorganisms. The other staining methods listed, such as gram stain, acid-fast stain, and methylene blue stain, are not specific for identifying Cryptococcus neoformans.

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  • 31. 

    Bacterial meningitis is accompanied by a cerebrospinal fluid that:

    • Is purulent and shows a cell count greater than 1000 WBCs/mm3

    • Shows a reduced glucose concentration

    • Shows a predominance of polymorphonuclear cells

    • All of these.

    Correct Answer
    A. All of these.
    Explanation
    Bacterial meningitis is characterized by an inflammatory response in the cerebrospinal fluid (CSF). This inflammation leads to the presence of purulent fluid, which is pus-like and often cloudy or opaque. Additionally, bacterial meningitis causes an increase in the number of white blood cells (WBCs) in the CSF, with a count greater than 1000 WBCs/mm3. The glucose concentration in the CSF is reduced in bacterial meningitis due to increased consumption by the bacteria. Finally, there is a predominance of polymorphonuclear cells, which are a type of white blood cell, in the CSF during bacterial meningitis. Therefore, all of these characteristics are seen in bacterial meningitis.

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  • 32. 

    Storage of media in a refrigerator reduces:

    • Deterioration

    • Dehydration

    • Both

    • Neither

    Correct Answer
    A. Both
    Explanation
    Storing media in a refrigerator reduces both deterioration and dehydration. Refrigeration slows down the chemical reactions that cause deterioration, such as the breakdown of organic compounds or the growth of microorganisms. Additionally, refrigeration helps to maintain the moisture content in the media, preventing dehydration which can lead to shrinkage, cracking, or loss of quality. Therefore, storing media in a refrigerator is an effective way to preserve its integrity and prolong its lifespan.

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  • 33. 

    A yeast has been isolated from a mouth culture. It forms germ tubes in the serum tube test. What is the genus and species of the yeast?

    • Candida albicans

    • Candida tropicalis

    • Cryptococcus neoforms

    • Torulopsis

    Correct Answer
    A. Candida albicans
    Explanation
    The yeast isolated from the mouth culture is identified as Candida albicans because it forms germ tubes in the serum tube test. Candida albicans is a common species of yeast that is often found in the mouth and other mucous membranes of humans. It is known to produce germ tubes as a characteristic feature, which helps in its identification. Other options such as Candida tropicalis, Cryptococcus neoforms, and Torulopsis do not exhibit this specific characteristic, making Candida albicans the correct answer.

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  • 34. 

    The cells that are destroyed in AIDS are ____ and their loss leaves the patient vulnerable to _____.

    • Cytotoxic lymphocytes; endotoxic shock

    • Monocytes and macrophages; lymphadenopathy

    • Antibody-producing; serious bacterial infections

    • T-helper lymphocytes; opportunistic infections

    Correct Answer
    A. T-helper lymphocytes; opportunistic infections
    Explanation
    T-helper lymphocytes are the cells that are destroyed in AIDS. Their loss leaves the patient vulnerable to opportunistic infections.

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  • 35. 

    Listeria monocytogenes has been shown to be the causative agent in:

    • Meningitis

    • Spontaneous abortions

    • Stillbirths

    • All of these

    Correct Answer
    A. All of these
    Explanation
    Listeria monocytogenes has been identified as the causative agent in various conditions, including meningitis, spontaneous abortions, and stillbirths. This bacterium is known to invade the central nervous system, leading to meningitis. Additionally, Listeria monocytogenes can cross the placental barrier, causing infections in pregnant women that may result in spontaneous abortions or stillbirths. Therefore, all of these conditions can be attributed to Listeria monocytogenes infection.

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  • 36. 

    One the distinguishing features of viruses is that they are:

    • Intracellular parasites

    • Gram-positive

    • Saprophytic

    • Nonpathogenic

    Correct Answer
    A. Intracellular parasites
    Explanation
    Viruses are considered intracellular parasites because they require a host cell to replicate and carry out their life cycle. They cannot reproduce or perform metabolic functions on their own. Instead, they invade host cells, hijack their cellular machinery, and use it to replicate and produce new viral particles. This dependence on host cells is a defining characteristic of viruses and sets them apart from other microorganisms.

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  • 37. 

    A zone of inhibition of growth on a plate containing a certain antibiotic indicates that:

    • The organism is resistant

    • There is antibiotic dependence

    • Mutants are predominant

    • The organism is susceptible or sensitive

    Correct Answer
    A. The organism is susceptible or sensitive
    Explanation
    A zone of inhibition of growth on a plate containing a certain antibiotic indicates that the organism is susceptible or sensitive to the antibiotic. This means that the antibiotic is effective in inhibiting the growth of the organism, suggesting that the organism is not resistant to the antibiotic. The presence of a clear zone around the antibiotic disk indicates that the organism is unable to grow in the presence of the antibiotic, indicating susceptibility.

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  • 38. 

    All of the following are bacilli except:

    • Brucella

    • Shigella

    • Treponema

    • Clostridia

    Correct Answer
    A. Treponema
    Explanation
    Treponema is the correct answer because it is a spirochete bacteria, not a bacillus. Bacilli are rod-shaped bacteria, whereas spirochetes have a spiral or corkscrew shape. Brucella, Shigella, and Clostridia are all examples of bacilli.

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  • 39. 

    Which of the following would best enhance the growth of pathogenic Neisseria species?

    • An incubator

    • A candle jar

    • An autoclave

    • Sabouraud agar

    Correct Answer
    A. A candle jar
    Explanation
    A candle jar would best enhance the growth of pathogenic Neisseria species. This is because Neisseria species are microaerophilic, meaning they require low levels of oxygen to grow. The candle jar creates a low oxygen environment by burning a candle inside a sealed container, depleting the oxygen and creating a favorable condition for the growth of Neisseria species. An incubator, autoclave, and sabouraud agar are not specifically designed to create a low oxygen environment and would not enhance the growth of Neisseria species.

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  • 40. 

    The organisms identified as alpha Streptococcus-Enterococcus group can be identified by which of the following set of biochemical media and/or test:

    • 6.5% NaCl, bile esculin

    • Optochin desoxycholate

    • Sodium hippurate, 6.5% NaCl

    • Bacitracin, bile esculin

    Correct Answer
    A. 6.5% NaCl, bile esculin
    Explanation
    The organisms identified as alpha Streptococcus-Enterococcus group can be identified using the combination of 6.5% NaCl and bile esculin. This specific combination of biochemical media and/or test helps in differentiating and identifying these organisms.

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  • 41. 

    Staphylococcus aureus is a:

    • Gram positive, non-motile coccus occurring in irregular clusters

    • Gram negative, non-motile coccus occurring in irregular clusters

    • Gram-positive motile coccus occurring in irregular clusters

    • Gram-negative motile coccus occurring in irregular clusters

    Correct Answer
    A. Gram positive, non-motile coccus occurring in irregular clusters
    Explanation
    Staphylococcus aureus is classified as a gram-positive bacterium because it retains the crystal violet stain during the Gram staining process. It is also described as a non-motile coccus because it has a spherical shape and does not possess flagella for movement. Additionally, it occurs in irregular clusters, which is a characteristic arrangement for Staphylococcus aureus.

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  • 42. 

    Which of the following will not grow on most artificial laboratory media:

    • Pseudomonas aeruginosa

    • Salmonella typhi

    • Salmonella flexneri

    • Treponema pallidum

    Correct Answer
    A. Treponema pallidum
    Explanation
    Treponema pallidum is the correct answer because it is a bacterium that causes syphilis and is highly fastidious, meaning it has very specific and complex nutritional requirements for growth. It cannot grow on most artificial laboratory media due to its specialized needs, making it difficult to cultivate and study in a laboratory setting. In contrast, Pseudomonas aeruginosa, Salmonella typhi, and Salmonella flexneri are all bacteria that can grow on most artificial laboratory media.

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  • 43. 

    The 100x objective lens with a 10x ocular lens provides an overall magnification of:

    • 10x

    • 100x

    • 1000x

    • 10000x

    Correct Answer
    A. 1000x
    Explanation
    The overall magnification is determined by multiplying the magnification of the objective lens with the magnification of the ocular lens. In this case, the objective lens has a magnification of 100x and the ocular lens has a magnification of 10x. Multiplying these two values together gives us an overall magnification of 1000x.

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  • 44. 

    In the API system, like many other testing systems, fermentation of sugars is indicated by:

    • Yellow

    • Blue

    • Green

    • Purple

    Correct Answer
    A. Yellow
    Explanation
    The correct answer is yellow because in the API system, fermentation of sugars is indicated by a color change to yellow. This is a common indicator used in testing systems to determine if fermentation has occurred.

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  • 45. 

    The reaction on urease agar test medium depends on the hydrolysis of urea, which is in turn dependent on the:

    • Breakdown of urea to ammonia; rendering the medium alkaline

    • Breakdown of urea to an acid endpoint

    • Formation of H2S, as indicated by a black product

    • Formation of gas bubble in the agar butt.

    Correct Answer
    A. Breakdown of urea to ammonia; rendering the medium alkaline
    Explanation
    The correct answer is the breakdown of urea to ammonia, which renders the medium alkaline. Urease is an enzyme that catalyzes the hydrolysis of urea into ammonia and carbon dioxide. The presence of urease-positive bacteria will cause the breakdown of urea, resulting in the production of ammonia. This increase in alkalinity can be detected by the change in color of the urease agar medium.

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  • 46. 

    An alpha Streptococcus has been isolated from urine, and it hydrolyzes esculin. To which serological group of streptococci does this organism belong?

    • A

    • B

    • C

    • D

    Correct Answer
    A. D
    Explanation
    The alpha Streptococcus isolated from urine that hydrolyzes esculin belongs to serological group D.

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  • 47. 

    For more accurate stool examinations:

    • One specimen is sufficient

    • 24 hour specimens are preferred.

    • 3 or more fresh specimens are recommended

    • Only refrigerated specimens are acceptable

    Correct Answer
    A. 3 or more fresh specimens are recommended
    Explanation
    To ensure more accurate stool examinations, it is recommended to provide three or more fresh specimens. This is because multiple samples increase the chances of detecting any abnormalities or pathogens that may be present in the stool. Fresh specimens are preferred as they provide a more accurate representation of the current state of the gastrointestinal tract, as compared to older or preserved samples. By providing multiple fresh specimens, healthcare professionals have a better chance of identifying any potential issues or infections.

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  • 48. 

    Which of the following would be the best preparation for rapid detection of Cryptococcus neoformans in a spinal fluid?

    • Gram stain

    • 10% KOH

    • India ink

    • Acid-fast stain

    Correct Answer
    A. India ink
    Explanation
    India ink is the best preparation for rapid detection of Cryptococcus neoformans in a spinal fluid. India ink is commonly used to stain the capsule of Cryptococcus neoformans, which is a key diagnostic feature of this organism. The capsule appears as a clear halo around the yeast cells when viewed under a microscope with India ink staining. This method allows for quick visualization and identification of Cryptococcus neoformans, making it the most suitable option for rapid detection in spinal fluid samples.

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  • 49. 

    Spreading surface growth with typical fruity odor is characteristic for:

    • Proteus

    • Pseudomonas

    • Shigella

    • Salmonella

    Correct Answer
    A. Pseudomonas
    Explanation
    Pseudomonas is known to produce a fruity odor as it spreads on surfaces. This odor is a result of the production of certain volatile compounds by the bacteria. This characteristic fruity odor is not commonly associated with other bacteria such as Proteus, Shigella, or Salmonella. Therefore, the presence of spreading surface growth with a typical fruity odor is indicative of Pseudomonas.

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Quiz Review Timeline (Updated): Mar 22, 2023 +

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  • Current Version
  • Mar 22, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Apr 28, 2013
    Quiz Created by
    Amandaregal

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