Bacterial Sepsis Differential Diagnoses

Updated: May 22, 2017
  • Author: Burke A Cunha, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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DDx

Diagnostic Considerations

Sepsis is not a random occurrence and is usually associated with other conditions (see Table 1 below). [18, 19, 20] Noninfectious conditions that present similarly to sepsis must also be considered, as should the host's immunocompetence.

Table 1. Clinical Conditions Associated With Sepsis (Open Table in a new window)

Associated With Sepsis (Fever ≥102°F) Not Associated With Sepsis (Fever ≤102°F)
GI tract source



Liver



Gallbladder



Colon



Abscess



Intestinal obstruction



Instrumentation



GI tract source



Esophagitis



Gastritis



Pancreatitis



Small bowel disorders



GI bleeding



GU tract source



Pyelonephritis



Intra- or perinephric abscess



Renal calculi



Urinary tract obstruction



Acute prostatitis/abscess



Renal insufficiency



Instrumentation in patients with bacteriuria



GU tract source



Urethritis



Cystitis



Cervicitis



Vaginitis



Catheter-associated bacteriuria (in otherwise healthy hosts without genitourinary tract disease)



Pelvic source



Peritonitis



Abscess



Upper respiratory tract source



Pharyngitis



Sinusitis



Bronchitis



Otitis



Lower respiratory tract source



Community-acquired pneumonia (with asplenia)



Empyema



Lung abscess



Lower respiratory tract source



Community-acquired pneumonia (in otherwise healthy host)



Intravascular source



IV line sepsis



Infected prosthetic device



Acute bacterial endocarditis



Skin/soft-tissue source



Osteomyelitis



Uncomplicated wound infections



Cardiovascular source



Acute bacterial endocarditis



Myocardial/perivalvular ring abscess



Cardiovascular source



Subacute bacterial endocarditis



  CNS source



Bacterial meningitis



CNS = central nervous system; GI = gastrointestinal; GU = genitourinary; IV = intravenous.
Adapted from: Cunha BA, Shea KW. Fever in the intensive care unit. Infect Dis Clin North Am. Mar 1996;10(1):185-209. [18]

Pseudosepsis

The most common medicolegal error is failure to consider pseudosepsis as a cause of the presenting syndrome complex. Most causes of pseudosepsis are readily treatable and reversible if recognized and treated early.

Thus, before embarking on a workup for sepsis or beginning empiric antibiotic therapy, it is vital first to rule out the treatable causes of pseudosepsis early in the disease process. Consider other causes or conditions that mimic the clinical and hemodynamic parameters of sepsis (see Table 2 below). The causes of pseudosepsis must be identified because they require supportive, rather than antimicrobial, therapy.

Table 2. Noninfectious Conditions Mimicking Clinical and Hemodynamic Parameters of Sepsis (Open Table in a new window)

Clinical Presentations Mimicking Sepsis Hemodynamic Parameters Mimicking Sepsis
Hemorrhage Acute pancreatitis
Pulmonary embolism Anaphylaxis
Myocardial infarction Spinal cord injury
Pancreatitis Adrenal insufficiency
Diabetic (abdominal crisis) ketoacidosis  
Systemic lupus erythematosus flare with abdominal crisis  
Ventricular pseudoaneurysm  
Massive aspiration/atelectasis  
Systemic vasculitis  
Diuretic-induced hypovolemia  

Pseudosepsis is a common cause of misdiagnosis in hospitalized patients, particularly in the emergency department (ED) and in medical and surgical intensive care units (ICUs). The most common causes of pseudosepsis include gastrointestinal (GI) hemorrhage, pulmonary embolism, acute myocardial infarction (MI), acute pancreatitis (edematous or hemorrhagic), diuretic-induced hypovolemia, and relative adrenal insufficiency.

Patients with pseudosepsis may have fever, chills, leukocytosis, and a left shift, with or without hypotension. All causes of pseudosepsis produce Swan-Ganz catheter readings that are compatible with sepsis (eg, increased cardiac output and decreased peripheral resistance), which could misdirect the unwary clinician (see Table 3 below).

Table 3. Characteristics of Pseudosepsis and Sepsis (Open Table in a new window)

Parameters Pseudosepsis Sepsis
Microbiologic No definite source PLUS ≥1 abnormalities



Negative blood cultures excluding contaminants



Proper identification/process/source PLUS ≥1 microbiologic abnormalities



Positive buffy coat smear result OR 2/3 or 3/3 positive blood cultures



Hemodynamic ⇓ PVR



⇑ CO



⇓ PVR



⇑ CO



Left ventricular dilatation



Laboratory ⇑ WBC count (with left shift)



Normal platelet count



⇑ FSP



⇑ Lactate



⇑ D-dimers



⇑ PT/PTT



⇓ Albumin



⇓ Fibrinogen



⇓ Globulins



⇑ WBC count (with left shift)



⇓ Platelets



⇑ FSP



⇑ Lactate



⇑ D-dimers



⇑ PT/PTT



⇓ Albumin



Clinical ≤102°F ±



Tachycardia ±



Respiratory alkalosis ±



Hypotension



≥102°F OR



Hypothermia ±



Mental status changes ±



Hypotension



CO = cardiac output; FSP = fibrin split products; GI = gastrointestinal; GU = genitourinary; PT/PTT = prothrombin time/partial thromboplastin time; PVR = peripheral vascular resistance; WBC = white blood cell.

Host immunocompetence

Otherwise healthy hosts with community-acquired pneumonia virtually never present with hypotension or sepsis; however, patients with decreased or absent splenic function may present with overwhelming pneumococcal sepsis. If an otherwise healthy patient with community-acquired pneumonia presents with shock and all of the other causes of pseudosepsis are ruled out, then it must be assumed that the patient is a compromised host with impaired or absent splenic function.

Differential Diagnoses