Question 1

Which of the following Gram-negative bacteria is a diplococcus responsible for causing both a sexually transmitted infection and a form of bacterial meningitis?

Accepted Answer

Neisseria

Question 2

A patient presents with a severe cough characterized by paroxysms followed by a 'whoop' sound. Which Gram-negative bacillus is most likely responsible for this disease, and what is the best method of prevention?

Accepted Answer

Bordetella pertussis; vaccination

Question 3

Which of the following bacteria is known for producing a blue-green pigment called pyocyanin, and is a common cause of hospital-acquired infections?

Accepted Answer

Pseudomonas aeruginosa

Question 4

A 7-year-old child develops a rapidly progressing pneumonia after exposure to a pet cat. Which Gram-negative bacterium is most likely responsible?

Accepted Answer

Bartonella henselae

Question 5

Which of the following bacteria is transmitted primarily by the bite of infected fleas and is the causative agent of plague?

Accepted Answer

Yersinia pestis

Question 6

A patient develops a urinary tract infection after a prolonged hospital stay. The isolated Gram-negative bacillus is highly motile and produces urease. Which organism is most likely responsible?

Accepted Answer

Proteus mirabilis

Question 7

Which of the following bacteria is a common cause of community-acquired pneumonia in children and can be prevented by a conjugate vaccine?

Accepted Answer

Haemophilus influenzae

Question 8

A laboratory technician is working with a Gram-negative coccobacillus that causes undulant fever and is commonly transmitted through unpasteurized dairy products. Which bacterium is this?

Accepted Answer

Brucella melitensis

Question 9

Which of the following bacteria is most likely to cause a severe gastrointestinal illness after ingestion of contaminated poultry, and is known for its ability to invade intestinal epithelial cells?

Accepted Answer

Salmonella enterica serovar Typhimurium

Question 10

A patient presents with a high fever, severe headache, and a maculopapular rash after cleaning a barn. The causative agent is an obligate intracellular Gram-negative bacterium. Which organism is most likely responsible?

Accepted Answer

Coxiella burnetii

Question 11

Which of the following bacteria is a common cause of hospital-acquired pneumonia, is encapsulated, and is known for producing thick, mucoid colonies?

Accepted Answer

Klebsiella pneumoniae

Question 12

A patient develops watery diarrhea after eating undercooked beef. The isolated Gram-negative bacillus is a lactose fermenter. Which organism is most likely responsible?

Accepted Answer

Escherichia coli

Question 13

Which of the following bacteria is transmitted by inhalation of aerosolized water droplets from air conditioning systems and causes a severe form of pneumonia?

Accepted Answer

Legionella pneumophila

Question 14

A patient presents with bloody diarrhea and a history of recent travel to a developing country. The causative agent is a non-motile Gram-negative bacillus. Which organism is most likely responsible?

Accepted Answer

Shigella sonnei

Question 15

Which of the following bacteria is a Gram-negative coccobacillus that causes tularemia and is commonly transmitted by handling infected rabbits?

Accepted Answer

Francisella tularensis

Question 16

A hospital outbreak of urinary tract infections is traced to a Gram-negative bacillus that forms red pigment at room temperature. Which organism is most likely responsible?

Accepted Answer

Serratia marcescens

Question 17

Which of the following bacteria is most likely to cause a zoonotic infection in veterinarians and is characterized by undulating fever?

Accepted Answer

Brucella melitensis

Question 18

A patient with a history of chronic lung disease develops a severe pneumonia after exposure to contaminated water. The Gram-negative bacillus is oxidase positive and does not ferment lactose. Which organism is most likely responsible?

Accepted Answer

Pseudomonas aeruginosa

Question 19

Which of the following bacteria is a Gram-negative diplococcus that can cause septicemia and a petechial rash in young adults living in close quarters?

Accepted Answer

Neisseria meningitidis

Question 20

A patient presents with a fever and lymphadenopathy after being scratched by a cat. Which Gram-negative bacterium is most likely responsible for this condition?

Accepted Answer

Bartonella henselae

Pathogenic Gram-Negative Bacteria: Structure, Diseases, and Clinical Features

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