7. Anaerobes and Peritonitis Flashcards
What infection is associated with intrauterine devices?
Actinomycosis
What features of an infection suggest that it may be caused by anaerobes?
Adjacent to mucosa Free gas Foul smell Not responding to gram positive antibiotics CNS manifestations
Why is particularly important to bring gram negative samples to the lab promptly?
They have been exposed to oxygen so will begin to die quickly
How do anaerobes inhibit phagocytosis?
Produce short chain fatty acids
What host factors can increase the risk of a gram negative infection?
Impaired gag or cough
Trauma and tissue ischaemia (so lack oxygen)
GI surgery
Amputation in a patient with peripheral vascular disease
Antibiotics
What are the symptoms of a clostridia tetani infection?
Muscle rigidity and spasms that last minutes, ongoing for 3-4 weeks
Exacerbated by noise, light and touch
What is the name of the neurotoxin produced by clostridia tetani?
Tetanospasm
Blocks inhibitory neurons
What type of vaccine is the tetanus vaccine?
Toxoid
What ways does clostridia tetani commonly enter the body?
Spores are introduced via skin trauma or on umbilical stump and germinate in the local anaerobic environment
May also contaminate heroin
How long is the incubation period for tetanus?
14 days
What does the muscle spasm appear like in tetanus?
Arm flexion
Leg extension
Back arch
Lockjaw
‘Risus sardonicus’ due to increased tone of orbicularis oris
May also cause laryngospasm and autonomic dysfunction
What can autonomic dysfunction cause in tetanus?
Arrhythmias
Sweating
What is the management for tetanus?
Early recognition essential, ABCs as may need to intubate
Treat infected source; debridement and metronidazole
Neutralise toxin with tetanus immunoglobulin
What effect does the botulinum toxin have?
Flaccid paralysis
Inhibits release of ACh at the neuromuscular junction
What are the types of botulinism?
Foodborne
Infant
Wound associated (including IVDU)
What is the typical cause of foodborne botulinism?
Homemade canned foods
Spores germinate in the anaerobic environment and produce toxins
Onset of symptoms after 12-36 hours
What is the common source of infant botulinism?
Raw honey
Spores are ingested and germinate in the underdeveloped GIT
What are the symptoms of infant botulinism?
Constipation
Muscle weakness: ‘Floppy baby’
What are the symptoms of botulinism?
Symmetrical descending flaccid paralysis
Bilateral cranial nerve palsy
Resp failure
No fever and no loss of consciousness
What lab test can be used to diagnose botulinism?
Toxin in stool, vomit or wound site
What is the management of botulinism?
ABCs as resp failure possible
Botulism Ig or babyBIg
Wound debridement and metronidazole
What is the range of disease associated with c. difficile?
Anything from diarrhoea to life threatening inflammation of colon (pseudomembrane colitis)
Children are commonly colonised but rarely infected
High risk of recurrence within 8 weeks
What antibiotics increase the risk of c.diff infection?
Fluoroquinolones
B-lactams
Clindamycin
What toxins are associated with c. diff?
A and B toxins
What is the management for a c. diff infection?
Isolate with contact precautions
Hand washing as spores survive alcohol
PCR stool for toxin gene: Toxin EIA
What antibiotics are used to treat c.diff infection?
Vancomycin or fidaxomicin
Given PO so that it acts locally in the gut
What toxin does c. perfringens produce?
Lecithinane
Perforates cell membrane
What infections are caused by c. perfringens?
Gas gangrene
Emphysematous cholecystitis
Food poisoning
What is the management for gas gangrene?
Surgical debridement
High dose penicillin or clindamycin
What is peritonitis?
Inflammation of the peritoneum, exudate becomes purulent
What are the types of peritonitis?
Spontaneous Bacterial Peritonitis
Secondary
Peritonitis complicating peritoneal dialysis
What are the signs of peritonitis complicating peritoneal dialysis?
Cloudy dialysis fluid
Less likely to be caused by anerobes: think skin flora
What are the symptoms of peritonitis?
Acute abdomen: pain, tenderness, rigidity
What anaerobes are associated with SBP?
E.coli Klebsiella Strep pneumo Group A strep Entercocci
What is secondary peritonitis?
Spillage of GI or GU into the peritoneal cavity
What is the empiric treatment for secondary peritonitis?
B-lactam with a B-lactamase inhibitor
and gentamicin
