Micro: Abscesses Flashcards
What is the pathogenesis of abscesses?
extension of normal flora beyond normal anatomic boundaries (usually polymicrobial and anaerobes)
direct inoculation of exogenous microbial pathogens
following hematogenous dissemination (s. aureus)
usually involve efforts by host to wall off inf
What are clinical signs of abscesses?
persistent systemic signs (esp fever and increased WBC)
signs and symptoms that depend on abscess location
usually, but not always, pain
What is the pathogenesis of a lung abscess?
aspiration of upper airway secretions due to: altered consciousness, periodontal dz/gingivitis, bronchial obstruction, dysphagia
What are the clinical manifestations of lung abscesses?
systemic signs, productive cough w foul smelling sputum, pleuritic chest pain
How are lung abscesses diagnosed?
clinical situation
CXR
microbiologic dx difficult b/c sputum and pus contain same normal oral flora - if drainage is needed, THAT can be submitted for cultures
What is the pathogenesis of liver abscesses?
antecedent intra-abdominal event (esp biliary tract inf)
sometimes hematogenous, rarely amebic
significant amt are cryptogenic (unkown why)
What is the microbiology of liver abscesses?
enteric flora if origin is intra-abdominal
usually staph when hematogenous origin
What are the clinical manifestations of liver abscesses?
RUQ pain/tenderness, tender hepatomegaly
may be extremely indolent
nausea, anorexia, weight loss
How are liver abscesses diagnosed?
H&P, LFTs (alk phos)
CT and MRI important
microbiologic dx by CT or ultrasound guided needle aspiration and catheter drainage (which is also therapeutic)
What is the pathogenesis of an intra-abdominal abscess?
localized or diffuse peritonitis most common antecendent event
maybe primary pathologic process in GI tract or trauma
characteristic locations (drainage pathways, spaces, etc)
What is the microbiology of intra-abdominal abscesses?
usually polymicrobial
enteric gram-, enterococci, anaerobes most common
What are the clinical manifestations of intra-abdominal abscesses?
ab pain/tenderness
subphrenic abscess may have pleuritic pain
fever, increased WBC, sepsis syndrome
How are intra-abdominal abscesses diagnosed?
H&P, routine and contrast Xrays
CT and MRI scans
radionuclide scans sometimes
microbiologic dx by CT guided aspiration - use anaerobic transport medium
What is the pathogenesis of spinal paravertebral abscess?
usually hematogenous
begins as vertebral osteomyelitis and extends through disc space to involve adjacent vertebra
sometimes direct extension from retroperitoneal space, mediastinal lymph node (tb(Potts)), or overlying skin ulcer
What is the microbiology of spinal paravertebral abscess?
s. aureas mostly
e. coli, pseudomonas, tb, salmonella, fungi and anaerobes in the rest
