Question 1

Which of the following bacteria is most commonly associated with severe gastrointestinal disease, possible systemic infection, and is transmitted via the fecal-oral route, often through contaminated food or water?

Accepted Answer

Salmonella enterica Typhi

Question 2

A patient presents with painful muscle contractions, especially in the neck and jaw, after stepping on a rusty nail. Which bacterium is most likely responsible, and what is a key feature of its biology?

Accepted Answer

Clostridium tetani; it forms endospores and is an obligate anaerobe

Question 3

Which of the following pathogens is a major cause of bacterial sexually transmitted infections and infectious blindness worldwide, and is an obligate intracellular pathogen?

Accepted Answer

Chlamydia trachomatis

Question 4

A 25-year-old presents with a bull’s-eye rash, joint pain, and facial paralysis after a hiking trip in Maine. Which bacterium is most likely responsible, and what is its vector?

Accepted Answer

Borrelia burgdorferi; deer ticks

Question 5

Which of the following bacteria is known for its extreme antibiotic resistance, is dangerous for immunocompromised patients (such as those with cystic fibrosis), and is commonly found in hospital equipment?

Accepted Answer

Pseudomonas aeruginosa

Question 6

Which bacterium is associated with peptic ulcers and stomach cancer, infects about two-thirds of the world’s population, and is transmitted via contaminated food and water?

Accepted Answer

Helicobacter pylori

Question 7

A child presents with a high fever, spotted rash, and a history of exposure to lice during a refugee crisis. Which bacterium is most likely responsible, and what is a key epidemiological fact?

Accepted Answer

Rickettsia prowazekii; caused epidemics during WWI and WWII

Question 8

Which of the following is TRUE regarding Mycobacterium tuberculosis?

Accepted Answer

It is Gram-positive, has a waxy cell wall, and lives inside macrophages

Question 9

Which bacterium is the causative agent of whooping cough, and what is the best prevention method?

Accepted Answer

Bordetella pertussis; DTaP vaccine

Question 10

A patient develops severe diarrhea with blood and mucus in the stool after eating contaminated food. The pathogen is only found in the human gut and produces Shiga toxin. Which bacterium is responsible?

Accepted Answer

Shigella dysenteriae

Question 11

Which of the following bacteria is most associated with the Black Death and is transmitted by rodent fleas or respiratory droplets?

Accepted Answer

Yersinia pestis

Question 12

Which bacterium is a common cause of pneumonia in young adults, has no cell wall, and is often called 'walking pneumonia'?

Accepted Answer

Mycoplasma pneumoniae

Question 13

A patient presents with fever, papule at the site of a cat scratch, malaise, and swollen lymph nodes. Which bacterium is most likely responsible?

Accepted Answer

Bartonella henselae

Question 14

Which of the following is a facultative anaerobe, ferments carbohydrates, and is mostly harmless but can cause traveler's diarrhea if pathogenic strains are ingested?

Accepted Answer

Escherichia coli

Question 15

Which bacterium is part of the normal vaginal flora but can cause vaginosis if it multiplies too quickly, and is not considered an STI?

Accepted Answer

Gardnerella vaginalis

Question 16

A hospital patient develops severe diarrhea and colitis after antibiotic treatment for another infection. The stool has a strong odor. Which bacterium is most likely responsible?

Accepted Answer

Clostridiodes difficile

Question 17

Which bacterium is responsible for diphtheria, produces a potent toxin, and was a leading cause of childhood death before 1935?

Accepted Answer

Corynebacterium diphtheriae

Question 18

Which of the following is TRUE about Streptococcus pyogenes?

Accepted Answer

It is specific to humans, destroys phagocytes, and is hemolytic on blood agar

Question 19

Which bacterium is associated with the production of a neurotoxin that can cause muscle paralysis and is often linked to improperly canned foods?

Accepted Answer

Clostridium botulinum

Question 20

A college student living in a dormitory develops a sudden headache, fever, and stiff neck. Which bacterium is a likely cause, and what is a key prevention strategy?

Accepted Answer

Neisseria meningitidis; vaccination

Survey of the Microbial World: Medically Important Bacteria

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