This document provides information on pyrexia of unknown origin (PUO). It defines PUO as a temperature greater than 101°F on multiple occasions for more than 3 weeks without a diagnosis. Common causes discussed include infections (such as tuberculosis, endocarditis, and abscesses), cancers, and autoimmune disorders. The document outlines approaches to evaluating a patient with PUO, including taking a thorough history, conducting a physical exam, and performing staged laboratory investigations and imaging studies. It emphasizes starting with basic tests before moving to more invasive studies. The document also discusses indications for immediate empirical antibiotic therapy versus continued observation and targeted therapy based on diagnostic clues.
3. Regulates normal body temperature
Normal Rectal temp. being
97.7-99.5°F
Oral temp. being 0.7°F
lower than rectal
while axillary being 1.2°F
lower than rectal.
Daily normal variation
being 0.5-1°F
With evening temperatures
being higher than the
morning
If body temp. exceeds
normal variation in an
individual, that’s called
FEVER
4. Liebermiester’s Rule: With each degree centigrade
rise in body temp. , heart rate increase by 8 per min
Except in those diseases where relative bradycardia
sets in.
6. DURACK & STREET’S CLASSIFICATION
CLASSIC
PUO
• 3 OUTPATIENT VISITS OR 3 DAYS IN HOSPITAL W/O ELUCIDATION OF CAUSE
• OR 1 WEEK OF “INTELLIGENT AND INVASIVE” AMBULATORY INV.
NOSOCOMIAL
PUO
•IN HOSPITALISED PATIENTS TEMP> 101°F DEVELOPS ON SEVERAL OCCASIONS WHO IS
RECEIVING ACUTE CARE AND WHOM WAS NOT MANIFEST OR INCUBATING AT TIME OF
ADMISSION
•3 DAYS OF INV. INCLUDING ATLEAST 2 DAYS INCUBATION OF CULTURES
NEUTROPENIC
PUO
•TEMP> 101°F ON SEVERAL OCCASIONS IN PATIENTS WHOSE NEUTROPHIL
COUNT IS <500uL(n 2-7x10^3) OR EXPECTED TO FALL WITHIN 1-2 DAYS
•NO SPECIFIC CAUSE IDENTIFIED 3 DAYS OF INV. INCLUDING ATLEAST 2 DAYS INCUBATION OF
CULTURES
HIV-
ASSOCIATED
PUO
• >101°F ON SEVERAL OCCASIONS OVER A PERIOD OF >4 WEEKS FOR
OUTPT. OR >3 DAYS FOR INPT. WITH HIV
•NO SOURCE REVELAED OVER 3 DAYS INV. INCLUDING 2 DAYS
INCUBATION OF CULTURES
9. INFECTIONS
Bacterial Infection: Common etiologies
•Chronic sinusitis
•Mastoiditis
•Salmonellosis
•Abscesses(subdiaphragmatic,liver,renal,retroperitoneal,
paraspinal)
•Chronic prostatitis
•Pyelonephritis
•Bacterial endocarditis(esp if caused by HACEK group)
•Osteomyelitis(esp in cases of implantation of
prostheses)
17. A 45 year old man was admitted to the ICU
with acute MI, thrombolysed and
reperfused, but then went into persistent
hypotension following a cardiac arrest. He
developed fever on Day 5. Routine blood
investigation showed a polymorpho-
nuclear leucocytosis. Blood culture was
diagnostic.
What could it be???
18. NOSOCOMIAL PUO
ETIOLOGY
Infections
Non infectious cause
Undiagnosed
Others
•Accounts for 50%
• suspects will be I/V lines, prothesis, septic
phlebitis
•Focused approach on sites where occult
infection may be present eg sinuses of intubated
patients.
Accounts for 25%
•Acalculous cholecystitis
•DVT
•Pulmonary Embolism
Includes drug fever,
withdrawal or
transfusion rxns or post
myocardial infarction
syndrome.
20% remains undiagnosed
19. A 14 year old boy was admitted with high grade
fever and pallor. On examination no
hepatosplenomegaly, lymphadenopathy or bone
tenderness were present. The blood counts were
as follows: Hb 8gm%, TLC 3800, P8 L86 E4 M2,
ESR 20 mm in 1st hr. Platelet count 2.5 lakhs.
What could it be???
20. NEUTROPENIC INFECTIONS
Patients on chemotherapy or immune deficiencies are more
susceptible to:
•Oppurtunistic bacterial infections
•Fungal infections like candidiasis
•Bacteremic infections
•Infections involving catheters
•Perianal infections
Most common etiological agents are:
•Aspergillus
•Candida
•CMV
•Herpes simplex
21. HIV – associated PUO
HIV Infection as such may be the cause
Other secondary causes are:
Pulmonary Tuberculosis
Pneumocystis Infection
Toxoplasmosis
Salmonellosis
Cryptococciosis
Cytomegalovirus infection
M. Avium or M. Intracellulare
Non-Hodgkin’s Lymphoma
Drug induced fever
23. HISTORY TAKING
History of present illness
1)Onset :
• Acute: Malaria, pyogenic infection
• Gradual: TB, typhoid fever
2) Character:
high grade- UTI, TB, malaria, drug
3) Pattern: Whether returns to normal or not
• Sustained/ persistent: typhoid, drugs
27. • Past Medical History
– Malignancy = leukemia, lymphoma, hepatocellular ca
– HIV infection
– DM
– IBD
– collagen vascular disease-SLE, RA, giant cell arteritis
– TB
– Heart disease: valvular heart disease
• Past Surgical History
– Post splenectomy/ post- transplantation
– Prosthetic heart valve
– Catheter, AV fistula
– Recent surgery/ operation
28. • Drug History
– Drug fever occur within 3 months after
start of drugs
• may cause low grade fever, usually
associated with rash
• Due to the allergic reaction, direct effect of
drug which impair temperature regulation
(e.g. phenothiazine)
• E.g. Antiarrhythmic drug: procainamide,
quinidine; Antimicrobial agent: penicillin,
cephalosporin, hydralazine
– After fever: may modify clinical pictures,
mask certain infection e.g. SBE, antibiotic
allergy
46. • Continued observation and
examination
• Therapy based on probability of
various causes of fever in that setting
• Avoid shotgun empirical approach
• Antibiotic??- mask infection
47. Indication for immediate
empirical therapy
• Vital instability
• Neutropenia
• Nosocomial- if bacteremia, fungemia or
persistently high viral loads are a threat
• Cirrhosis, asplenia, immunosuppressive
drug use, exotic travel, environmental
exposures
48. • change IV lines(culture), drugs
stopped for 72 hours and empirical
therapy started
• Vancomycin (MRSA) with
piperacilin/tazobactum(broad
spectrum gram negative)
49. • Granulomatous hepatitis or positive
TST- therapeutic trial for TB upto
6wks
• Glucocorticoids and NSIADS- trial
only after ruling out any infections.
Dramatic response in autoimmune
diseases.
Last resort- if fever continues uptil 6 mnths
50. Initiation of empirical therapy
• Doesnot mark end of treatment
• Rather it commits physician to more
• Thoughtful
• Reeaxamination and
• Evaluation
