Gram-negative — MCQs

A 35-year-old man seeks evaluation at a clinic with a 2-week history of pain during urination and a yellow-white discharge from the urethra. He has a history of multiple sexual partners and inconsistent use of condoms. He admits to having similar symptoms in the past and being treated with antibiotics. On genital examination, solitary erythematous nodules are present on the penile shaft with a yellow-white urethral discharge. The urinalysis was leukocyte esterase-positive, but the urine culture report is pending. Gram staining of the urethral discharge showed kidney bean-shaped diplococci within neutrophils. Urethral swabs were collected for cultures. Which of the following best explains why this patient lacks immunity against the organism causing his recurrent infections?

A 59-year-old man comes to the physician because of urinary frequency and perineal pain for the past 3 days. During this time, he has also had pain with defecation. He is sexually active with his wife only. His temperature is 39.1°C (102.3°F). His penis and scrotum appear normal. Digital rectal examination shows a swollen, exquisitely tender prostate. His leukocyte count is 13,400/mm3. A urine culture obtained prior to initiating treatment is most likely to show which of the following?

A 27-year-old man is brought to the emergency department shortly after sustaining injuries in a building fire. On arrival, he appears agitated and has shortness of breath. Examination shows multiple second-degree burns over the chest and abdomen and third-degree burns over the upper extremities. Treatment with intravenous fluids and analgesics is begun. Two days later, the patient is confused. His temperature is 36°C (96.8°F), pulse is 125/min, and blood pressure is 100/58 mm Hg. Examination shows violaceous discoloration and edema of the burn wounds. His leukocyte count is 16,000/mm3. Blood cultures grow gram-negative, oxidase-positive, non-lactose fermenting rods. The causal organism actively secretes a virulence factor that acts primarily via which of the following mechanisms?

A neonate appears irritable and refuses to feed. The patient is febrile and physical examination reveals a bulge at the anterior fontanelle. A CSF culture yields Gram-negative bacilli that form a metallic green sheen on eosin methylene blue (EMB) agar. The virulence factor most important to the development of infection in this patient is:

A 26-year-old man comes to the emergency department for evaluation of burning with urination and purulent urethral discharge for the past 3 days. He is sexually active with multiple female partners. Several months ago he was diagnosed with urethritis caused by gram-negative diplococci and received antibiotic treatment with complete resolution of his symptoms. A Gram stain of the patient's urethral discharge shows gram-negative intracellular diplococci. Which of the following properties of the infecting organism most contributed to the pathogenesis of this patient's recurrent infection?

A 55-year-old woman with type 2 diabetes mellitus is admitted to the hospital because of a 2-day history of fever, breathlessness, and cough productive of large quantities of green sputum. She drinks 8 beers daily. Her temperature is 39°C (102.2°F), pulse is 110/min, respirations are 28/min, and blood pressure is 100/60 mm Hg. Blood and sputum cultures grow gram-negative, catalase-positive, capsulated bacilli. Which of the following components of the causal organism is the most likely cause of this patient's hypotension?

A 65-year-old woman undergoes an abdominal hysterectomy. She develops pain and discharge at the incision site on the fourth postoperative day. The past medical history is significant for diabetes of 12 years duration, which is well-controlled on insulin. Pus from the incision site is sent for culture on MacConkey agar, which shows white-colorless colonies. On blood agar, the colonies were green. Biochemical tests reveal an oxidase-positive organism. Which of the following is the most likely pathogen?

A 15-year-old female is brought to the emergency room with high fever and confusion. She complains of chills and myalgias, and physical examination reveals a petechial rash. Petechial biopsy reveals a Gram-negative diplococcus. The patient is at greatest risk for which of the following?

A 49-year-old woman presents to her physician with a fever accompanied by chills and burning micturition since the past 5 days. She is an otherwise healthy woman with no significant past medical history and has an active sexual life. On physical examination, her temperature is 39.4°C (103.0°F), pulse rate is 90/min, blood pressure is 122/80 mm Hg, and respiratory rate is 14/min. Examination of the abdomen and genitourinary region do not reveal any specific positive findings. The physician orders a urinalysis of fresh unspun urine for this patient which shows 25 WBCs/mL of urine. The physician prescribes an empirical antibiotic and other medications for symptom relief. He also orders a bacteriological culture of her urine. After 48 hours of treatment, the woman returns to the physician to report that her symptoms have not improved. The bacteriological culture report indicates the growth of gram-negative bacilli which are lactose-negative and indole-negative, which produce a substance that hydrolyzes urea to produce ammonia. Which of the following bacteria is the most likely cause of infection in the woman?

A young man about to leave for his freshman year of college visits his physician in order to ensure that his immunizations are up-to-date. Because he is living in a college dormitory, his physician gives him a vaccine that prevents meningococcal disease. What type of vaccine did this patient likely receive?