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Microbiology, P2S2 > Lecture 3 - Pyrexia of Unknown Origin > Flashcards

Lecture 3 - Pyrexia of Unknown Origin Flashcards

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1
Q

Learning Outcomes

A

Define FUO (Classical and risk group). Describe the diagnostic evaluation of FUO. List the key pathogens in specific patient groups. Describe the presentation, investigation and antibiotic treatment of infective endocarditis

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2
Q

Define Fever

A

A common complaint of patients presenting to a doctor. The cause is usually immediately apparent or is discovered within a few days, or the temperature settles spontaneously.

  • Exogenous or endogenous pyrogens
  • Common Symptom - May have a protective effect
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3
Q

Define a Fever of Unknown Origin

A
  • > 38.3 degrees
  • several occasions
  • continues for more than 3 weeks, DESPITE 1 week of evaluation
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4
Q

What is the most common cause of FUO

A

Infection

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5
Q

List a few other important causes of FUO

A
    • Malignancies
  • Auto Immune Diseases
  • *non infectious causes must be differentiated from infections in patients with FUO upon examination
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6
Q

In what percentage of patients have an FUO without probable cause

A

5-15%

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7
Q

List the 4 categories of FUO

A

Classical

Nomocomial (hospital aquired)

Neutropenic

HIV - associated

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8
Q

Define Classical FUO

A
  • <38.3 degrees
  • Several times
  • More than 3 week duration
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9
Q

Define Nosocomial FUO

A
  • >38.3 degrees
  • Several times
  • Hospitalized
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10
Q

Define Neutropenic FUO

A
  • >38.3 degrees
  • Several times
  • Neutrophil Count is <500/mm3
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11
Q

Define HIV - associated FUO

A
  • >38.3 degrees
  • HIV positive
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12
Q

List bacterial examples of infection

A
  • TB
  • Enteric Fever
  • Ostemyelitic
  • Endocarditis
  • Brucellosis
  • Abcess (intra-abdominal)
  • Billiary System Infection
  • Urinary Tract Infection
  • Lyme Disease
  • Leptospiros
  • Q fever
  • Typhus
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13
Q

Name the cause of each PARASITIC infection

  1. Malaria
  2. Amoebic Abcesses
  3. Toxoplasmosis
A
  1. Plasmodium Species
  2. Entamoaeba Histolytica
  3. Toxoplasma Gondii
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14
Q

Name the Cause of Each Fungal Infection

  1. Candidiasis
  2. Histplasmosis
A
  1. Candida Albicans
  2. Histoplasma Capsulatum
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15
Q

Name examples of Viral Infections

A
  • Hepatitis
  • AIDS
  • Infectious Mononucleosis
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16
Q

Explain the 2 divisions of Aetiology

A

1. Specific Pathogens

  • TB and Typhoid fever caused by specific pathogens

2. Variety of Different pathogens

  • UTI
  • Billiary Tract Infections
  • Abcesses
  • *all may be caused by different organisms
17
Q

List the groups of people who may suffer severe infections WITHOUT presenting with pyrexia

A
  • Seriously ill neonates
  • Elderly
  • Patients with uraemia
  • Patients on corticosteroids
  • Patients on continous anti-pyretic therapy
18
Q

Due to the extensive nature of Infections, name the first steps in investigation of the cause

A
  • Extensive History
  • Examination
  • Screening Tests
19
Q

Outline the necessary Questions to be asked in a History

A
  • Travel
  • Occupation
  • Hobbies
  • Exposure to animals
  • Known infectious hazards
  • AB therapy within the previous 2 months
  • Substance Misuse
  • Other Habits
20
Q

Why is a travel history important

A

Some Infections are…

1) Zoonosis

  • Leptospirosis
  • Spotted Fevers

2) Vector Borne

  • Malaria
  • Trypanasmosis

3) Limited to Geographic Distribution

  • Histoplasmosis
21
Q

Highlight the key components of an examination

A
    • Eyes
  • Hands
  • Face
  • Lymph Nodes
  • Abdomen
  • Ausculatation of Heart
22
Q

What is the minimum diagnostic evaluation necessary to diagnose FUO (Classical)

A
  • Comprehensive history (including travel, STI risk, hobbies, pets, occupation etc.)
  • Comprehensive physical examination (including temporal arteries, ENT, rectal examination, etc.)
  • Routine blood tests (FBP, ESR,CRP)‏
  • Cultures of blood, urine
  • Chest radiograph &

Abdominal ultrasound

  • Antinuclear and antineutrophilic cytoplasmic antibodi, rheumatoid factor
23
Q

Give Examples of FURTHER evaluations that can be done to confirm FUO

A

Directed by abnormalities detected by above test

  • HIV antibodies depending on detailed history
  • CMV-IgM and EBV serology in case of abnormal differential WBC count
  • Abdominal or chest helical CT scan
  • Echocardiography in case of cardiac murmur
24
Q

Explain the typical causes of Nosocomial FUO

A

1) Vascular Line Related - Staphylococci

2) Cholecystitis and Pancreatitis - Gram negative rods

3) Pneumonia (related to assisted ventillation) - Gram negative rods (psuedomonas)

4) Post-Op abcesses (Intra-abdominal) - Gram negative rods, anerobes

25
Q

Explain the typical causes of Neutropenic FUO

A

1) Vascular Line Related

  • Staphylococci

2) Oral Infection

  • Candida
  • Herpes SImplex Virus

3) Pneumonia

  • Candida
  • CMV
  • Gram negative rods
  • Aspergillus

4) Soft tissue

  • peri-anal abcess - Mixture of anaerobes and aerobes
26
Q

Explain the typical causes of HIV - associated FUO

A

1) Respiratory tract

  • Pneumocystis
  • Mycobacterium

2) Central nervous system

  • Toxoplasma

3) Gastrointestinal tract

  • Salmonella
  • Campylobacter
  • Shigella

4) Genital tract

  • Treponema pallidum
  • Neisseria gonorrhoeae
27
Q

Explain the Pathogenesis of Endocardiditis

Name the Most common cause

where it comes from

Give an example

Comment on Fibrin

A
  • Endogenous infection acquired when organisms entering the bloodstream establish themselves on the heart valves.
  • Most commonly streptococci from the oral flora enter the bloodstream,
  • For example during dental procedures or vigorous teeth cleaning or flossing
  • Fibrin-platelet vegetations are present on damaged valves before the organisms implant, organisms multiply and attract further fibrin and platelet deposition.
28
Q

Infective Endocarditis: Patient Profile

A

Majority of patients have…

  • Pre-existing heart defect
    • *Either congenital or Aquired (as a result of Rheumatic Fever)
  • Prosthetic heart valve in-situ
29
Q

Explain the common causes of Infective Endocarditis

A
  • Almost any organism can cause Endocarditis
  • BUT native valves are almost are usually infected by oral streptococci or staphylococci
30
Q

Infective Endocarditis: Clinical Presentation

A

Almost Always:

Fever - Heart Murmur

Also, Related to 4 ongoing Processes:

1) Infectious process on the valve and the local intracardiac complications
2) Septic Embolisation
3) Bacteremia, often with metastatic focci of infection
4) Circulating Immune Complexes and other factors

31
Q

In ADDITION to a fever and a heart murmur, what other symptoms may patients complain of

1) Non specific
2) Peripheral Manifestation
3) Other

A

Non- Specific

  • Weight loss
  • Anorexia
  • Malaise
  • Chills -
  • Nausea -
  • Vomiting -
  • Night sweats

Peripheral Manifestations

  • Splinter Hemmorhage
  • Osler’s Nodes

Other

  • Microscopic haematuria due to immune complex deposition in the kidney
32
Q

Comment on the mortality of EC, pre and post AB

A

Pre AB = 100%

Post AB = 20-50% *

AB resitance has developed

33
Q

How long will it take to eradicate the infection, why is this and comment on relapse

A

Eradication takes several weeks to achieve

Due to:

  • Inaccessibility of the organisms within the vegetations (both to antibiotics and to host defenses) -
  • The organism’s high population density and relatively slow rate of multiplication
  • Antibiotics work best on rapidly dividing bacteria *Relapse is NOT COMMON
34
Q

List the causative organisms associated with Endocarditis

1) Native Valve
2) Early Prosthetic Valve
3) Late Prosthetic Valve

A

1) Native valve

  • Oral streptococci (viridans group) such as Streptococcus sanguis - Strep. oralis - Strep. mitis - Staph. aureus.
  • *Intravenous drug misusers have the added complication of infection due to organisms they inject into themselves. (gram negatives)‏

2) Early prosthetic valve

  • Coagulase-negative staphylococci are common causes of endocarditis and are probably acquired at the time of surgery.

3) Late prosthetic valve

  • More than 3 months after cardiac surgery like those causing native valve endocarditis
35
Q

Explain the neccessary Investigations completed to diagnose endocarditis

A
  • Blood culture = most important test
  • Ideally, three separate samples of blood should be collected within a 24-h period and before antimicrobial therapy is administered.
  • Isolation of the causative organism is essential so that antibiotic susceptibility tests can be performed and optimum therapy prescribed.
36
Q

Comment on culture negative endocarditis

A
  • Difficult to grow organisms
  • Antibiotic presence
  • Q fever (Coxiella burnetii)
37
Q

Treatment

  1. What does the type of AB depend on
  2. Virdans Streptococci
  3. Enterococci
  4. Staphylococci
  5. Duration
A

1. Susceptibility of the organ

2. Virdans Streptococci

  • Penicillin susceptible streptococci use high doses of penicillin
  • Penicillin + Aminoglycoside

3. Enterococci

  • Amoxicillin and Aminoglycoside

4. Staphylococci

  • Flucloxicillin and aminoglycoside
  • Vancomycin

5. Duration

  • 4 Weeks
  • 6 Weeks if prosthetic valve
  • Monitor CRP for response to therapy
38
Q

Case

75 years-old lady presents with 1 week of

Malaise, nausea loss of appetite

Past history of aortic valve surgery

On examination

Flushed, temp=38.2oC

Systolic murmur

What investigations?

A
  • Blood culture
  • To be done whilst she is febrile
  • AB treatment can wait until patient sensitivites have been determined

Microbiology, P2S2 (1 decks)

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