C. diff Flashcards
Properties of c.diff
gram positive anaerobic spore forming motile increasingly resistant to antibiotics
what can infection with c.diff cause
asymptommatic
diarheoa/colitis
pseudomembranous colitis
fulminant colitis
risk factors for c.diff
current or recent antobiotics increased age serious underlying disease surgery immunocompromise use of PPI
others: NG tube ICU long course of antibiotics multiple antibiotics specific antibiotics - clindamycin, cephalasporin and penecillins
how can c.diff be ‘carried’ asymptomatically
in neonates - usually asymptomattic but can indicate cross infection healthy adults hospital patients on skin in domestic animals
define healthcare associated c.diff
onset of symptoms at least 48 hours after admission to healthcare establishment or 4 weeks after dicharge
define community associated c.diff
onset of symptoms occur while the patient is outside of hospital and without disscharge from a hospital within the previous 12 weeks
or symptoms onselt within 48 hours of admission
describe pathogenesis of c diff
gi tract normal flora comprimised eg by antibiotics
gut is colonised by c diff spores
spores ingested and evade the host defences where they germinate and produce toxins a and b
virulence factors (properties that allow a pathogen to establish or maintain effects of infection)
toxins a and b
attachment to mucuso
binary toxin cdt
spore production and survival
how do the toxins affect the gut
pro inflammatory cytokines induced
recruitment of neutrofils
increased fibrin —> pseudomembrane forms
toxin A - causes apotosis of eneterocytes
what are the clinical effects of the toxins
loss of fluid by leakage through damaged mucosa
reduced absoption through gut wall
formation of pseudomembranesg
general gut inflammation, toxic megacolon and perforation risk
can be fatal if v severe
signs and symptoms of c. diff
diarheoa ilerus toxic megacolon fever rigors sepsis septic shock peritonnitis signs increased white cells raised creatinine raised lactate ascitites
what is severe c.diff infection
c diff infection with one or more signs of severe colitis
c diff in patients of advanced age ICU, immunocompromised
severe SIRS
what is diarheoa
passing 3 or more unformed stools per day or more than is normal for the patient
NEVER formed stool
how is c. diff investigated
stool culture - must be an unformed stool
detects the toxin by culture
can also detect toxin via immunoassays but less sensitive (quicker though)
can also detect toxin be molecular emthod
what is the gold standard test for c diff
cytoToxin Assay for toxin B
how is c diff epidemiologcially typed
by ribotyping (PCR)
name the hypervirulent strain of c diff
027
treatment of c diff
non severe - oral metronidazole
severe - oral vanc +/- IV met
