A 58-year-old man comes to the emergency department with a 1-day history of fever, headache, and vomiting. He underwent kidney transplantation last year. His temperature is 39.4 C (103 F), blood pressure is 130/80 mm Hg, pulse is 98/min, and respirations are 16/min. Neck stiffness is present on physical examination. Cerebrospinal fluid (CSF) results are as follows: Gram-positive rods with tumbling motility at room temperature are seen on CSF microscopy. How was this patient's infection most likely transmitted?

Question

A 58-year-old man comes to the emergency department with a 1-day history of fever, headache, and vomiting.  He underwent kidney transplantation last year.  His temperature is 39.4 C (103 F), blood pressure is 130/80 mm Hg, pulse is 98/min, and respirations are 16/min.  Neck stiffness is present on physical examination.  Cerebrospinal fluid (CSF) results are as follows:  Gram-positive rods with tumbling motility at room temperature are seen on CSF microscopy.  How was this patient's infection most likely transmitted?

Quizplus · Accepted Answer

This patient, who is almost certainly taking anti-rejection immunosuppressants given his kidney transplantation, has fever, headache, neck stiffness, and cerebrospinal fluid (CSF) findings suggestive of bacterial meningitis. There is CSF pleocytosis (elevated leukocyte count) with left shift, elevated protein, and low-normal glucose (low CSF glucose is seen in most though not all bacterial meningitis cases); and bacteria are seen on CSF microscopy. The microbiologic findings are consistent with Listeria monocytogenes infection; this is a facultative intracellular (grows within macrophages), gram-positive rod, with distinctive flagellar-based tumbling motility (typically seen at room temperature but not at human body temperatures). Listeria can multiply in cold temperatures (4-10 C [39.2-50 F]), a unique feature that allows it to grow well in refrigerated foods. Listeriosis most often occurs in immunocompromised adults (eg, renal transplantation, hematologic malignancy). The bacteria can access the bloodstream following ingestion of contaminated food (eg, unpasteurized milk and milk products, undercooked meats, unwashed raw vegetables) and cause meningitis, meningoencephalitis, or bacteremia. Listeria can also be transmitted transplacentally or via vaginal contact during delivery, causing neonatal meningitis. Ampicillin is the antibiotic of choice. (Choice A) Among the diseases transmitted by arthropod bites are: leishmaniasis (sandfly bite), Plasmodium/malaria (Anopheles mosquito bite), Chagas disease (reduviid bug bite), and Borrelia burgdorferi/Lyme disease (Ixodes tick bite). (Choice C) Needlesticks can transmit HIV, hepatitis B and C, and other infections. (Choice D) Neisseria meningitidis, Haemophilus influenzae, Mycobacterium tuberculosis, and many other organisms are transmitted via respiratory droplets. Listeria infections are not transmitted in this manner. (Choice E) Unprotected sex is the mode of transmission of HIV, hepatitis B, gonorrhea, chlamydia, syphilis, human papillomavirus (a cause of cervical cancer), and others. Educational objective: Listeriosis is most commonly transmitted through food ingestions and can cause meningitis in immunocompromised adults. Listeria is a gram-positive rod with tumbling motility. It grows well in cold temperatures and can therefore contaminate refrigerated food. __________ References: What is new in listeriosis? (http://www.ncbi.nlm.nih.gov/pubmed/24822197) Listeria monocytogenes regulates flagellar motility gene expression through MogR, a transcriptional repressor required for virulence. (http://www.ncbi.nlm.nih.gov/pubmed/15302931)

A 58-Year-Old Man Comes to the Emergency Department with a 1-Day