A 69-year-old man is admitted to the hospital due to 2 days of high fevers, chills, headache, nausea, and diarrhea. He has also had intermittent abdominal pain associated with 4 nonbloody bowel movements over the past 24 hours. The patient has a history of rheumatoid arthritis and takes infliximab and hydroxychloroquine. He lives with his wife in Florida and has had no sick contacts or recent travel outside of the state. He is the primary caretaker of a domesticated bird.
Temperature is 39.4 C (103 F), blood pressure is 118/80 mm Hg, pulse is 112/min, and respirations are 16/min. The patient is ill-appearing. Pulmonary examination is normal. Bowel sounds are hyperactive, and the abdomen is soft and mildly tender. Neurological examination shows no focal abnormalities.
Laboratory results are as follows:
Chest x-ray reveals no focal infiltrate. Intravenous empiric antibiotics and fluids are administered. Blood cultures sent on admission grow Gram-positive rods in all 4 bottles after 12 hours.
Which of the following is the most likely etiology of this patient's illness?

Question

A 69-year-old man is admitted to the hospital due to 2 days of high fevers, chills, headache, nausea, and diarrhea.  He has also had intermittent abdominal pain associated with 4 nonbloody bowel movements over the past 24 hours.  The patient has a history of rheumatoid arthritis and takes infliximab and hydroxychloroquine.  He lives with his wife in Florida and has had no sick contacts or recent travel outside of the state.  He is the primary caretaker of a domesticated bird.
Temperature is 39.4 C (103 F), blood pressure is 118/80 mm Hg, pulse is 112/min, and respirations are 16/min.  The patient is ill-appearing.  Pulmonary examination is normal.  Bowel sounds are hyperactive, and the abdomen is soft and mildly tender.  Neurological examination shows no focal abnormalities.
Laboratory results are as follows:
 Chest x-ray reveals no focal infiltrate.  Intravenous empiric antibiotics and fluids are administered.  Blood cultures sent on admission grow Gram-positive rods in all 4 bottles after 12 hours.
Which of the following is the most likely etiology of this patient's illness?

Quizplus · Accepted Answer

11ec193a_96fc_7dfe_853d_9b7162188ddf_MD0002_00 This patient has acute febrile gastroenteritis, underlying immunosuppression (infliximab), and bacteremia with Gram-positive rods, raising suspicion for Listeria monocytogenes infection. Listeria is found in soil and decaying vegetation and is often a low-level contaminant of food (eg, fruit, unpasteurized milk, soft cheeses). Healthy individuals who ingest large inoculums are at risk for self-limited (<48 hours) febrile gastroenteritis. Those with advanced age or underlying immunosuppression can also develop invasive disease (eg, bacteremia, sepsis, pneumonia, meningitis). Listeriosis is usually suspected clinically and confirmed by fluid (eg, blood, cerebrospinal fluid) cultures. Gastroenteritis does not typically require antimicrobial treatment, but ampicillin is the first-line therapy for invasive infection. (Choice B) Contact with respiratory secretions can lead to viral infections (eg, influenza). Listeria is primarily spread through food ingestion, not respiratory secretions. (Choice C) Exposure to antibiotics is associated with Clostridium difficile colitis, but bacteremia is very rare. In addition, this patient has no recent history of antibiotic use. Gram-positive bacteremia is more suggestive of Listeria or Clostridium perfringens. (Choice D) Exposure to bird feces is associated with psittacosis due to Chlamydia psittaci and cryptococcosis due to Cryptococcus neoformans. Neither of these infections is associated with febrile gastroenteritis or Gram-positive bacteremia. (Choice E) Bacterial overgrowth usually causes bloating, flatulence, and abdominal discomfort, not acute febrile gastroenteritis. In addition, most cases arise due to Gram-negative organisms and anaerobes. Educational objective: Listeriosis usually occurs due to the ingestion of contaminated food. Healthy individuals are at risk for self-limited febrile gastroenteritis, but those with immunosuppression or advanced age can also develop invasive disease (eg, bacteremia, sepsis, pneumonia, meningitis). Ampicillin is the first-line treatment for invasive infection. __________ References: Listeriosis: a resurgent foodborne infection. (http://www.ncbi.nlm.nih.gov/pubmed/20002687) Gastroenteritis due to Listeria monocytogenes. (http://www.ncbi.nlm.nih.gov/pubmed/15825036)

A 69-Year-Old Man Is Admitted to the Hospital Due to 2