Infections and Sepsis Flashcards
how is gut flora a supraorganism
A system of multiple organisms that may be considered a single organism
describe the normal flora of the gut- good or bad?
beneficial indigeous microbiota
do you have the same normal flora all the time
no, may be transient, not all colonisation is normal
when does colonisation of normal gut flora begin
at birth
what help prevents colonisation in the GI tract
stomach acidity, normal flora, peristalsis, antimicrobial compounds
what traits increase an invaders chance of success
high growth rates, dispersal capability, phenotypic plasticity, genetic diversity
what is a barrier to establishment of an invader after introduction
abiotic resistance: pH, temperature, salinity
what is biotic resistance
barrier to invasion: competition, antagonism, predation
what organisms are commonly in the normal flora of the large bowl
enterobacteriaceae, (klebsiella), enterococci, milleri group streptococci, anaerobic gram +ve bacilli (clostridium), anaerobic gram -ve bacilli (bacteroides, candida)
are there more bugs in the large/ small bowl?
small, number increases as you go towards the rectum
what are the steps of pathogenic adhesion
exposure, adhesion, invasion, colonisation, toxicity, tissue damage and disease
what is colonisation
the establishment of a microorganism on or within a host
what is a pathogen
any microorganism that has the potential to cause disease
what is virulence
the likelihood of causing disease (opportunistic or accidental pathogen)
what investigations should be done when diagnosing an infection
radiology, biochemistry, immunology, microbiology (blood, stool, urine, wound, tissue cultures), microscopy: (of stool, urine, CSF, sputum, pus) serology, antigen detection, PCR/ molecular studies
what are the components of inflammation
calor (heat), rubor (redness), tumour (swelling), dolor (pain), functio laesa (loss of function)
what happens in the incubation period
pathogen replicates in the host
what happens in the prodromal period
early signs and symptoms
what is the convalescent period
signs and symptoms recede, person returns to health
what immune response does bacteria usually initiat
phagocytes, antibody and t lymphocytes, complement
what immune response do viruses usually intiate
t lymphocytes, anti body and b lymphocytes
what immune response does fungi usually initiate
phagocytes, t lymphocytes, eosinophils
what immune response do protozoa usually intiate
t lymphocytes, eosinophils
what immune response do worms usually initiate
eosinophils, mast cells
what age groups are usually most susceptible to infection
neonates and the elderly
what infections of the abdomen can cause abscesses
hepatitis (liver abscesses)
gastroenteritis
perineal abscesses
what shape are enterobacteraeciae
bacilli
what shape are streptococcus and enterococcus
cocci
what shape are helicobacter pylori
spirochete
what do gram -ves have that gram +ves lack
lipopolysaccharide
what is usually the causative agent of oesophagitis
candida/ malfunctioning T cells
what causes pancreatitis
not usually caused by infection
what drives gram -ve sepsis
lipopolysaccharide
what further step is used distinguish enterobacteriaceae
lactose or non lactose ferminting
what is an abligate anaerobe
one that is poisoned by oxygen
how do you tell non lactose fermenting drugs apart
oxidase test, urease tests
what antibiotic do all UK E coli respond to
gentamycin
are enterobacteriaceae
gram -/+ve
negative
enterobacteriacae are coliforms- what is this
rod-shaped Gram-negative non-spore forming and motile (most) or non-motile bacteria which can ferment lactose with the production of acid and gas
how do enteronacteriaceae cause disease
motility- flagella
colonisation factors- fimbriae
endotoxin- cell wall component
enterotoxin- sgiga toxin
what enterobacteriaceae are not mobile
shigella and klebsiella
how does maldi-tof mass spectrometry identify bacteria
analyses the protein composition of bacteria cell wall, ionises the proteins, then uses a database
how does serotyping work
immunoreactivity of various antigens, relates to gram -ve, helps you identify bug by antigen reactions
what gram +ve organiams are found in the mouth
strep viridans
anaerobes
candida
neisseria
sthaphylococci
what gram +ve organisms can be found in the stomach
usually sterile- some candda and staphylococci may survive
name the most important enterobacteriaceae
e coli
where are most anaerobic and aerobic organism in the GI tract
aerobic closer to mouth- upper GI tract
anaerobic closer to rectum- lower GI tract
what is the main anaerobe to remeber
bacteroids and costridium
what is the normal flora of the bowel
small number of coliforms and anaerobes
what is the normal flora of the colon
lots of coliforms, anaerobes and enterococcus
what is the normal flora of the bile ducts
usually sterile
what antibiotic is used for anaerobes
metronidazole
what is cholangitis
an infection in the common bile duct, usually resulting from a common bile duct stone
what should you review after 48 hours of initial treatment
antibiotics, even if results from lab haven’t come back yet; change or IV/Oral switch if patient improving
how are enterococcus in the GI tract treated
amoxicillin (vancomycin if penicillin allergic)
cotrimoxalzole when time to switch to oral from IV
what are the antibiotics for an intra abdominal sepsis
treat as enterococcus:
amoxicillin (vancomycin if penicillin allergic)
cotrimoxalzole when time to switch to oral from IV
how do gall stones reach the liver
via bile ducts
how does malignancy spread to the liver
bile ducts and portal vein
how does bacteremia spread to the liver
portal vein and hepatic artery
what is sepsis
uncontrolled amplification of the immune response throughout the whole body- life-threatening organ dysfunction caused by a dysregulated host response to infection.
what is septic shock
a subset of sepsis with circulatory and cellular/ metabolic dysfunction associated with a higher risk of mortality
when do you know its sepsis
infection + news > 5
what could lead to an unusual host response
age, immunosuppressed, co morbidity, drugs, genetics
what is an occult
a disease of no readily discernible signs or symptoms
what should be done to treat sepsis
B-lood cultures + septic screen, U&Es U-rine output- monitor hourly F-luid resuscitation A-ntibiotics IV L-lactate measurement O-xygen to correct hypoxia
what could cause pain in the left iliac fossa on deep palpation
diverticular disease, inguinal hernia
what could cause pain in the right iliac fossa
appendicitis, inguinal hernia
what can cause pain in the epigastric region
peptic ulcer disease, cholecystitis, pancreatitis, MI
what can cause pain in the periumbilical region
small or large bowl obstruction, appendicitis, abdominal aortic aneursym
why are antibiotics not helpful in large abscesess
as they have no blood supply- need surgical drainage
what is a spontaneous peritonitis
think ascites- is an infection of ascitic fluid that cannot be attributed to any intra-abdominal, ongoing inflammatory, or surgically correctable condition
what is secondary peritonitis
an acute infection of the peritoneum due to loss of integrity of the gastrointestinal tract or other visceral organ (a burst that introduces the bacteria)
what antibiotic for enterococcus
amoxicillin
what antibiotic for enterobacteriaceae
gentamycin
what is the drug of choice for sepsis and enterococci in the GI tract
amoxicillin
what is the drug of choice for sepsis and coliforms
gentamycin
what is the mutant selection window
where the wrong dose of antibiotics selects the resistant sub population of the infection
