Microbiology and Parasitology Quiz

A genus of spirochetes that can cause Lyme disease.

The most common method for detecting Lyme disease is a blood test.

A corkscrew-shaped bacteria that causes syphilis.

The most common method for diagnosing syphilis is a blood test.

A spirochete that can be detected in blood samples, often before a doctor suspects leptospirosis.

A bacterium that produces orange, waxy colonies and is often detected in sputum of patients with leukemia.

A genus of bacteria that includes Mycoplasma pneumoniae, which can cause respiratory infections.

A bacterium that produces urease, commonly used for identification in the laboratory.

A gram-negative rod that is lactose-negative, indole positive, urease positive, ornithine decarboxylase positive, phenylalanine deaminase positive, and H2S negative.

The indole test is used to differentiate Klebsiella oxytoca from K. pneumoniae. K. oxytoca is indole positive, while K. pneumoniae is indole negative.

Certain organisms in the normal fecal flora, such as Proteus spp., can mimic the biochemical profile of Yersinia.

Yersinia strains are typically isolated from stool specimens on selective media such as Hektoen enteric agar. This medium inhibits the growth of most other intestinal bacteria while allowing Yersinia to grow and produce characteristic colonies.

Certain strains of Citrobacter freundii can sometimes be mistaken for Salmonella due to their ability to react with Salmonella polyvalent antiserum. This can cause false-positive results in agglutination tests meant to identify Salmonella.

A bloody stool culture with non-lactose fermenting colonies on MacConkey agar and blue-green colonies on Hektoen enteric agar, but no growth on Campylobacter blood agar or C. difficile agar suggests the presence of Shigella spp.

A test used to differentiate between different species of bacteria based on their ability to hemolyze red blood cells on blood agar.

A test where a small amount of hydrogen peroxide is added to a bacterial colony. If the colony produces bubbles, it is positive for catalase.

A test that differentiates Streptococcus species based on their ability to hemolyze red blood cells on blood agar in the presence of Staphylococcus aureus.

A type of bacterial culture media that contains a high concentration of glucose and a small amount of other sugars. This media is used to determine what sugars the bacteria can ferment.

A type of bacterial culture media that contains a high concentration of sulfur. This media is used to determine if the bacteria can produce hydrogen sulfide. H2S production is indicated by a black precipitate in the media.

A gram-positive, spore-forming rod that is often associated with food poisoning and can produce the toxin cereulide.

The process of identifying bacteria based on their characteristics, including shape, size, and staining properties. This process is important for determining the cause of an infection.

A group of gram-positive, spore-forming rods that can be found in the environment. Some species are associated with food poisoning, while others are used in the production of antibiotics.

A gram-negative, oxidase-positive, S-shaped rod that grows at 42°C, ferments glucose and xylose, is catalase-positive, motile, and hydrolyzes hippurate.

The optimal atmospheric condition for culturing Campylobacter spp. is a microaerophilic environment with reduced oxygen levels.

Stenotrophomonas maltophilia is a gram-negative bacterium that is oxidase-positive, catalase-positive, and grows at 42°C, but it is less likely to be the cause of the infection described in the question.

Burkholderia pseudomallei is a gram-negative bacterium that is oxidase-positive and catalase-positive, but typically does not grow at 42°C.

Pseudomonas aeruginosa is a gram-negative bacterium that is oxidase-positive, catalase-positive, and typically grows at 42°C, but it is not known to ferment glucose and xylose.

Acinetobacter spp. are gram-negative, oxidase-negative, and typically produce a characteristic 'mucus' like colony appearance, differing from the given characteristics.

Actinobacillus is a genus of small, gram-negative coccobacilli that is typically oxidase-positive and catalase-positive and is commonly found in animals. It can cause endocarditis, bacteremia, wound and dental infections in humans.

Tests such as DNase and VP, Indole and Lysine decarboxylase, or Growth on MacConkey and blood agar can be used to differentiate between various bacterial species.

Haemophilus species commonly associated with endocarditis.

Haemophilus species that require NAD (V factor) are easily grown on chocolate agar due to the presence of lysed red blood cells, which release NAD.

Haemophilus species that require the V factor (NAD) can grow around colonies of Staphylococcus or Neisseria species on sheep blood agar due to the release of NAD by these bacteria.

Haemophilus haemolyticus and Haemophilus parahaemolyticus can be identified using a combination of sheep blood agar and chocolate agar.

Haemophilus ducreyi is known to be difficult to isolate from genital ulcers and swollen lymph nodes.

Certain strains of Haemophilus influenzae are resistant to ampicillin due to their ability to produce β-lactamase enzymes, which inactivate the antibiotic.

A small, gram-negative coccobacillus recovered from cerebrospinal fluid (CSF) that tests positive for Indole, Glucose, and X factor requirement is likely Haemophilus influenzae.

Haemophilus influenzae can be differentiated from other species by its requirement for X factor (hematin) and V factor (NAD).

A nonfermenting bacterium that is oxidase positive, motile with polar monotrichous flagella, grows at 42°C, and produces dry, wrinkled or smooth, buff to light brown colonies that are difficult to remove from agar.

These bacteria are associated with immunodeficiency syndromes and melioidosis, a glanders-like disease in Southeast Asia and northern Australia.

Alcaligenes faecalis, formerly known as A. odorans, can be differentiated from Bordetella bronchiseptica by a rapid urease test.

Chryseobacterium isolates are readily distinguished from Acinetobacter spp. by their oxidase activity and ability to grow on MacConkey agar.

A gram-negative coccobacillus isolated from the CSF of an immunosuppressed patient on chocolate agar is most likely Chryseobacterium meningosepticum.

Burkholderia pseudomallei typically grows in moist soils, especially in tropical regions.

Pseudomonas aeruginosa is a well-known opportunistic pathogen, commonly associated with wound infections and hospital-acquired infections.

Acinetobacter spp. are typically oxidase-negative, making them distinguishable from Chryseobacterium spp. which are oxidase positive.