Category Archives: Cox’s Conference

Cox’s Conference: Enteric Fever

In last week’s Ambulatory Cox’s Conference, Dr. Roger Fan presented a case of a young female who presented with fevers, rash, and headache. Our expert discussant, Dr. James Luby guided us through the differential diagnosis for the constellation of symptoms – fever, rash, and headache.

In a patient with an acute presentation of fever, rash, and headache the differential diagnosis is broad and includes infectious, autoimmune, and drug-related reactions etiologies. It is important to elicit a thorough history from the patient including travel history, exposures (insects, animals, sick contacts), medications, immunization history, and immune status of the host. The patient had history of recent travel to Nepal to visit family. Our differential diagnosis in this patient included common viral illnesses (EBV, CMV, and HIV), tick-born illnesses (Rocky Mountain spotted fever, Ehrlichiosis/anaplasmosis, and Lyme disease), meningococcal infection, disseminated gonococcal infection, and travel related illnesses (Malaria, Dengue fever, Typhoid/paratyphoid (enteric fever), Zika and Chikungunya). The patient was diagnosed with Salmonella typhi (enteric fever).


Enteric Fever Pearls:

  • Classically caused by Salmonella enterica serotype Typhi, however other serotypes including S. enterica Paratyphi A, B, or C can cause a similar syndrome.1
  • Typhoid and enteric fever can be used interchangeably
  • More common in children and young adults
  • Most prevalent in poor areas with overcrowding and poor access to sanitation (south-central Asia, Southeast Asia, and southern Africa have the highest incidence of S. Typhi infection).
  • US has ~ 200-300 cases of S. Typhi per year (80% of these cases are in travels to countries where enteric fever is endemic). 2

Clinical Presentation:

  • Classic presentation includes fever, abdominal pain, constipation/diarrhea, “rose spots” (salmon-colored macules on trunk and abdomen), and headaches. Less common manifestations include cough, arthralgias/myalgias, intestinal perforation, and neurologic manifestations (encephalopathy, acute psychosis, myelitis, and disorded sleep patterns).1
  • Symptoms begin ~ 5-21 days after ingestion of the causative organism (typically through contaminated water or food).
  • Common laboratory derangements include cytopenias – anemia, leukopenia (leukocytosis more common in children), and elevated liver enzymes.


  • Must have high clinical suspicion in patients who have traveled to endemic areas.
  • Blood and stool cultures should be obtained. Blood cultures are 40-80% sensitive. Stool studies have a 30-40% sensitivity.1
  • Positive cultures can take several days to incubate, empiric therapy should be started in patients with a high clinical suspicion.
  • Serology testing can be performed, however positive results may represent prior exposure.


  • In patients with severe or complicated disease (organ dysfunction, systemic toxicity, or requires hospitalization), initial therapy with ceftriaxone is appropriate.3
  • In patients with uncomplicated disease who can be treated as an outpatient, fluroquinolone or azithromycin is first line.3
  • Multi-drug resistant strains of S.Typhi are prevalent worldwide. These strains can be commonly resistant to ampicillin, trimethoprim-sulfamethaxazole, and chloramphenicol. Increasing resistance to fluroquinolones is also a growing issue, particularly in South Asia.3



  1. Parry CM, Hien TT, Dougan G, et al. Typhoid fever. N Engl J Med 2002; 347:1770.
  2. Lynch MF, Blanton EM, Bulens S, et al. Typhoid fever in the United States, 1999-2006. JAMA 2009; 302:859.
  3. Kariuki S, Gordon MA, Feasey N, Parry CM. Antimicrobial resistance and management of invasive Salmonella disease. Vaccine 2015; 33 Suppl 3:C21.

Cox’s Conference: Hypokalemia

In today’s Cox’s Conference, Dr. Ezim Ajufo presented a case of profound hypokalemia to expert discussant, Dr. Biff Palmer. We had an excellent discussion about the differential diagnosis and mental framework for hypokalemia. A previous blog post that summarizes this framework is linked here: Cox’s Conference: Recurrent hypokalemia.

In addition to the linked blog post, additional pearls from our discussion are paraphrased here.

Manifestations and Consequences of Hypokalemia:

Clinical Symptoms and Signs
  • Muscle weakness (or paralysis in extreme cases)
    • Decreased extracellular potassium leads to hyperpolarization of cell membranes. This results in decreased sensitivity of muscle cells to generate an action potential to excitatory stimuli.
  •  Confusion or affective disorders
    • Alterations in central nervous system conduction due to membrane polarization disturbances
  • Ileus
    • Due to smooth muscle depolarization abnormalities due to membrane polarization disturbances
  • Rhabdomyolysis
    • Extracellular potassium normally mediates vasodilation. When muscle cells depolarize, intracellular potassium is released, leading to vasodilation and increased blood flow to the muscle fibers. In states of hypokalemia, this vasodilation is attenuated, leading to relative ischemia and rhabdomyolysis
  • Cardiac
    • EKG
      • U-wave amplitude increased (may be misread as QT prolongation)
      • ST depression
      • T-wave flattening
    • ventricular or supraventricular tachyarrhythmias
  • Renal
    • Impaired urinary concentration
      • leads to polyuria and polydipsia
      • due to decrease in the medullary gradient AND due to decreased responsiveness to antidiuretic hormone (mechanism poorly understood)
    • chronic tubulointerstitial nephropathy
  • Endocrine
    • Glucose intolerance/hyperglycemia
      • hypokalemia decreases pancreatic beta-cell insulin release


Am J Kidney Dis. 2010 Dec;56(6):1184-90.


Cox’s Conference: Left ventricular wall thickening…not always hypertension

In this week’s Cox’s Conference, Dr. Mehwish Ismaily presented a fascinating case of wet beri beri to expert discussant, Dr. Justin Grodin. During our discussion, there was an interesting segue into the differential diagnosis of left ventricular wall thickening. Key points and lessons are summarized here.  Continue reading Cox’s Conference: Left ventricular wall thickening…not always hypertension

Cox’s Conference: Should I get that renal biopsy?

In today’s Cox’s Conference, Dr. Donghai Wen presented a case of acute kidney injury with nephrotic range proteinuria due to collapsing glomerulopathy in a patient with sickle cell anemia to expert discussant Dr. Christopher Lu with guest discussant Dr. Allen Hendricks from the Department of Pathology. Below are key pearls generated from the discussion. Continue reading Cox’s Conference: Should I get that renal biopsy?

Cox’s Conference: Constriction vs. Restriction

In today’s Cox’s Conference, Dr. Grace Liu presented a case of suspected pericardial constriction to expert discussant, Dr. Ian Neeland. Below are key pearls and links to Dr. Neeland’s slideshow on restrictive versus constrictive heart disease and an excellent review from the Journal of the American College of Cardiology.  Continue reading Cox’s Conference: Constriction vs. Restriction

Cox’s Conference: Dermatology presentation

In today’s Cox’s Conference, dermatology resident, Dr. Meredith Orseth, along with expert discussant, Dr. Arturo Dominguez presented us with several dermatology cases through which we discussed the differential diagnosis of erythroderma, nail changes, and much more. Below is a link to the slideshow of the discussion.

Derm presentation with notes