Micro- Abscesses

Question 1

What are the 3 paths that can lead to abscess formation?

Answer 1

1. extension of normal flora beyond anatomical boundaries
2. direct inoculation by exogenous pathogen
3. hematogenous spread

ALL abscess formation requires efforts by the host defenses to wall off the infection

Question 2

What are the 2 main clinical manifestations of an abscess?

Answer 2

1. systemic
   - elevated WBC
   - fever
2. Localized
   - pain, swelling
   - signs depend on location [lungs v brain v cardiac tissue]

Question 3

A patient presents with altered consciousness. On examination, you note that she has gingivitis. She has an elevated WBC count and fever. She has a productive cough that smells foul and pleuritic chest pain. What kind of abscess is present?
What is the pathogenesis?

Answer 3

Lung abscess- usually due to aspiration of upper airway secretions

• altered consciousness
• gingivitis
• dysphagia
• bronchial obstruction [lung cancer]

Question 4

What is the microbiology of a lung abscess?

Answer 4

Mixed anaerobic and aerobic oral flora

Question 5

How is the diagnosis of a lung abscess made?

Answer 5

1. clinical presentation
2. CXR

microbiological diagnosis is difficult because expectorated sputum and lung abscess pus have the same flora.

Question 6

What is the pathogenesis of liver abscesses?

Answer 6

1. preceding intra-abdominal event like biliary tract infection
2. hematogenous spread
   - portal vein [sometimes amebic from intestinal focus]
   - hepatic artery
3. cryptogenic

Question 7

What is the microbiology of a liver abscess when it is caused by an antecedent intra-abdominal event?
What is the microbiology of a liver abscess when it is caused by hematogenous spread?

Answer 7

1. enteric flora if antecedent intra-abominal event

2. staph when hematogenous

Question 8

A patient presents with RUQ pain and tenderness. He has tender hepatomegaly. He says recently he has been experiencing nausea, anorexia and weight loss. Based on history and physical, what are you suspicious of?
What do you want to order to diagnose him?

Answer 8

Liver abscess:

1. LFTs [especially alk phos]
2. CT and MRI
3. microbiology diagnosis is often made by CT or US-guided needle aspiration and drainage

Question 9

What is the pathogenesis of intra-abdominal abscess?

Answer 9

1. antecedent localized or diffuse peritonitis
2. primary GI process
   - malignancy
   - perforated ulcer
   - appendicitis, diverticulitis
   - trauma
3. characteristic locations [drainage pathways/spaces]

Question 10

What is the microbiology of an intra-abdominal abscess?

Answer 10

1. polymicrobial
   - enteric G-
   - enterococci
   - anaerobes

Question 11

A patient presents with abdominal pain/tenderness, pleuritic chest pain, fever, increased WBC and sepsis syndrome.
What location of abscess are you concerned about?

Answer 11

Subphrenic abscess

Question 12

How do you diagnose an intra-abdominal abscess?

Answer 12

1. Hx and PE
2. routine, contrast CXR
3. CT and MRI
4. radionucleotide scan
5. microbio diagnosis by CT-guided aspiration

Question 13

What is the pathogenesis of spinal/paravertebral abscesses?

Answer 13

1. hematogenous spread [most]
2. begins as vertebral osteomyelitis and extends through the disc to involve adjacent vertebrae
3. direct extension from retroperitoneal space, mediastinal lymph nodes [Pott’s disease-TB] or overlying skin ulcer

Question 14

What causes the MAJORITY of spinal/paravertebral abscesses?

What causes the remaindeR?

Answer 14

Majority = staph aureus

Remainder:

1. E. coli
2. TB
3. pseudomonas aeruginosa
4. salmonella
5. fungi
6. anaerobes

Question 15

What are the clinical effects of a spinal/paravertebral abscess?

Answer 15

1. fever, elevated WBC
2. pain/localized tenderness
3. if it extends into epidural space and compresses spinal cord–> neuro symptoms

Question 16

How is the diagnosis of spinal abscess made?

Answer 16

1. Hx and PE
2. routine xray
3. radionucelotide scan
4. CT and MRI [VERY IMPORTANT]
5. micro diagnosis by CT-guided aspiration