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Nosocomial Fever of Unknown Origin

Kokila Kakarala MDa, Tim Chen DO

Correspondence to Kokila Kakarala, MD.
Email: kokilak@gmail.com

+ Author Affiliation - Author Affiliation
aA 4th medical student at Texas Tech University Health Sciences Center in Lubbock.
bAfellow in Infectious Disease at TTUHSC.

SWRCCC 2015;3(11):15-18
doi: 10.12746/swrccc2015.0311.139

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Case

A 28-year-old woman was admitted to the intensive care unit with severe respiratory distress secondary to uncontrolled asthma. In spite of standard acute asthma therapy, the patient’s mental status deteriorated, and she developed severe hypoxia requiring intubation. On day two of admission, the patient developed a fever of 38.7°C that persisted for four days without any known etiology after extensive laboratory work-up, chest x-rays, and an abdominal ultrasound. She is diagnosed with nosocomial fever of unknown origin. What is the appropriate work-up and management for patients with nosocomial fever of unknown origin, and what additional tests might help evaluate patients who are intubated?

Discussion

Fever is often a self-limiting occurrence in which an etiology can be promptly determined. However, in some circumstances fever can persist for an extended period of time without an identifiable cause in spite of an extensive work-up. This clinical scenario is called fever of unknown origin (FUO).1,2  Four categories of FUO are defined in Table 1. All categories share a temperature threshold of >38.3°C with varying duration, patient location, and confounding diagnoses.

Table 1: Durack and Street classification of fever of unknown origin3

Category

Distinguishing Factors

Classic

>3 weeks
Evaluation of ≥3 visits or 3 days in the hospital

Nosocomial

Patient hospitalized ≥24 hours without fever being present or incubating on admission
Evaluation of at least 3 days

Neutropenic

Evaluation of at least 3 days with absolute neutrophil count ≤500 per mm3

HIV associated

>4 weeks for outpatient and >3 days for inpatients with confirmed HIV infection

        
In pediatric hematology/oncology patients, bacteremia and fever of unknown origin were identified as the most common nosocomial infections.4 In a study of adult hematology/oncology patients, 33 FUOs were documented in 116 patients hospitalized for a total of 4,002 days, with 66.7% of the FUOs occurring when the patients were neutropenic.5

FUOs have multiple causes, and the list of diagnoses has changed over time secondary to widespread use of antibiotics, increased knowledge of disease pathology, and advances in diagnostic testing. For example, early imaging utilization has decreased the proportion of FUO caused by intra-abdominal abscesses and tumors. Infection continues to be the predominant cause of FUO followed by neoplasms and noninfectious inflammatory diseases. FUO is often caused by atypical presentations of common diseases, with endocarditis, diverticulitis, vertebral osteomyelitis, and extrapulmonary tuberculosis being the most frequent. The prevalence of infection as a leading cause is even more significant in non-Western nations, where tuberculosis accounts for up to 50% of cases in some countries.2 In some cases nosocomial fever occurs in postoperative patients after the release of cytokines and interleukins from tissue injury and not infection.6 In a prospective cross sectional study conducted in pediatric and adult ICUs (n=63), 82% of patients with nosocomial FUO were found to have acute bacterial nosocomial sinusitis diagnosed by microbiological analysis of sinus fluid aspirates.7 Other common causes of nosocomial FUO include drug fever, health care associated infections, thrombosis, pulmonary embolism, and neoplasm.2

Evaluation of FUO

FUO is a diagnosis made after thorough history taking, physical examination, and obligatory investigations as listed in Table 2. No symptom should be regarded as irrelevant due to the likelihood of atypical manifestations of common diseases with FUO. Repeating the history taking by different members of the team and gathering information from family and friends of the patient can also be valuable.1,2

 

Table 2: Initial evaluation for FUO

Specific factors to address in history for suspected FUO1

Sick contacts

Prosthetic devices

Living & working conditions

Tuberculosis exposure

Psychiatric illness

Recreational activities

Previous chronic infections

Prescribed medications

Dietary habits

History of transfusions

Over the counter medications

Recreational drugs

Diagnosis of malignancies

Herbal remedies

Sexual activity

Immunosuppressive therapy

Country of origin

Animal exposure

Indwelling foreign materials

Vaccination status

Travel history

 

Specific factors to address in physical examination for suspected FUO1

Fundi

Thyroid gland

Genital area

Conjunctivae

Lymphatic system

Pulses

Oropharynx

Heart murmurs

Skin

Temporal artery

Abdomen

Joints

 

Obligatory laboratory and imaging investigations2

Erythrocyte sedimentation rate

Total protein

Rheumatoid factor

C-reactive protein

Alkaline phosphatase

Protein electrophoresis

Platelet count

Alanine aminotransferase

Urinalysis

Leukocyte count

Aspartate aminotransferase

Blood cultures (n=3)

Leukocyte differential

Lactate dehydrogenase

Urine culture

Electrolytes

Creatine kinase

Tuberculin skin test

Creatinine

Ferritin

Chest x-ray

Hemoglobin

Antinuclear antibodies

Abdominal ultrasonography

 

In addition to imaging by chest x-ray and abdominal ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI) are often used. Since localizing signs or symptoms are often absent, clinicians have started to use positron emission tomography/computed tomography (PET/CT) to detect focal sites of inflammation.8 Sinusitis develops frequently in patients with orotracheal or nasotracheal intubation, limited mobilization, facial trauma, or prior sinus disease, and can be detected with sinus x-rays, ultrasound, or CT scans as part of the work-up for FUO.9

Case conclusion

Our 28-year-old patient has nosocomial fever of unknown origin and is currently intubated. She underwent the obligatory laboratory and imaging studies done for an FUO work-up, and later had sinus x-rays due to her intubation status. Other considerations included drug fever and venous thromboembolic disease.  Additionally, reevaluating the patient’s history and physical examination and speaking with family and friends of the patient brought attention to a previous history of sinus disease. With the additional studies our patient was found to have acute bacterial nosocomial rhinosinusitis and was started on the appropriate antibiotic treatment. Patients with FUO usually have good outcomes even without a diagnosis, and if there is no indication for a particular etiology, subsequent approaches include a “wait and see” strategy, whole body inflammation tracer scintigraphy, a staged approach, or therapeutic trials.10

Key points

  1.  There are four classifications of FUO, all requiring a fever >38.3°C and an extensive work-up (Table 1).
  2.  A thorough history and physical are crucial in determining the etiology of FUO, as atypical manifestations of common diseases often occur.
  3.  In patients who have been intubated, diagnostic imaging for sinusitis can be a valuable addition to the FUO work-up.

 

 

 

References

  1. Hayakawa K, Ramasamy B, Chandrasekar PH. Fever of unknown origin: an evidence-based review. Am J Med Sci 2012 Oct; 344(4):307-16.
  2. Bleeker-Rovers CP, van der Meer JWM. "Fever of unknown origin." Harrison's Principles of Internal Medicine, 19e. Eds. Dennis Kasper, et al. New York, NY: McGraw-Hill, 2015.  AccessMedicine. Web. 21 Apr. 2015. <http://accessmedicine.mhmedical.com/content.aspx?bookid=1130&Sectionid=79724594>.
  3. Durack DT, Street AC. Fever of unknown origin--reexamined and redefined. Curr Clin Top Infect Dis 1991; 11:35-51.
  4. Al-Tonbary YA, Soliman OE, Sarhan MM, Hegazi MA, El-Ashry RA, El-Sharkawy AA, Salama OS, Yahya R. Nosocomial infections and fever of unknown origin in pediatric hematology/oncology unit: a retrospective annual study. World J Pediatr 2011 Feb; 7(1):60-4.
  5. Engelhart S, Glasmacher A, Exner M, Kramer MH. Surveillance for nosocomial infections and fever of unknown origin among adult hematology-oncology patients. Infect Control Hosp Epidemiol 2002 May; 23(5):244-8.
  6. Kendrick JE, Numnum TM, Estes JM, Kimball KJ, Leath CA, Straughn JM Jr. Conservative management of postoperative fever in gynecologic patients undergoing major abdominal or vaginal operations. J Am Coll Surg 2008 Sep; 207(3):393-7.
  7. Noorbakhsh S, Barati M, Farhadi M, Mousavi J, Zarabi V, Tabatabaei A. Intensive care unit nosocomial sinusitis at the Rasoul Akram Hospital: Tehran, Iran, 2007-2008. Iran J Microbiol 2012 Sep; 4(3):146-9.
  8. Tokmak H, Ergonul O. The evolving role of PET/CT in fever of unknown origin. Int J Infect Dis 2014 Oct; 27:1-3.
  9. van Zanten AR, Dixon JM, Nipshagen MD, de Bree R, Girbes AR, Polderman KH. Hospital-acquired sinusitis is a common cause of fever of unknown origin in orotracheally intubated critically ill patients. Crit Care 2005 Oct 5; 9(5):R583-90.
  10. Knockaert DC, Vanderschueren S, Blockmans D. Fever of unknown origin in adults: 40 years on. J Intern Med 2003 Mar; 253(3):263-75.       

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Received: 04/25/2015
Accepted: 05/10/2015
Reviewers: Richard Winn MD
Published electronically: 07/15/2015
Conflict of Interest Disclosures: none

 

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