Microbiology - GI Flashcards
Which immune system components target bacteria?
Phagocytes, antibody/B lymphocytes and complement
Which immune system components target viruses?
T lymphocytes, antibody/B lymphocytes
Which immune system components target fungi?
Phagocytes, T lymphocytes, eosinophil
Which immune system components target protozoa?
T lymphocytes and eosinophils
Which immune system components target worms?
Eosinophils and mast cells
What is the basic mechanism behind peritonitis and what are some examples of causes?
Peritoneal cavity is normally sterile so leakage of bowel contents results in peritonitis
e.g. perforated duodenal ulcer, perforated appendix, perforated diverticulum
What are some local and systemic signs of peritonitis?
Local - pain, tenderness, guarding, blood PR
Systemic - fever, chills or rigors, N+V, constipation or diarrhoea, malaise, anorexia
What are the criteria for the qSOFA score?
RR>22bpm, sBP<100mmHg and GCS<14
Score of >2 = mortality of >10%
What are the criteria for SIRS (systemic inflammatory response syndrome)?
Temp >38 or <36
HR >90bpm
RR >20/min
WCC >12,000 or <4000 or >10% immature neutrophils
What can cause SIRS?
Infection, burns, trauma, pancreatitis
What is sepsis?
SIRS with a presumed or confirmed infectious process
What is septic shock?
Sepsis plus signs of at least one acute organ dysfunction e.g. renal, respiratory, unexplained metabolic acidosis
Sepsis with hypotension refractory to adequate volume resuscitation
What are some common bacteraemia sources in the community?
E.coli (urine, abdomen) Strep pneumoniae (respiratory) Staph aureus (usually MSSA skin)
What are some common bacteraemia sources in hospital?
E.coli (catheter related or abdomen)
Staph aureus (line or wound related)
Enterococci (urine, wound, line)
Klebsiella (urine, wound)
What are coliforms?
E.coli and similar organisms that inhabit the large bowel, such as Klebsiella, Proteus, Enterobacter and Serratia species
What is a strict aerobe?
Organism that requires oxygen for growth e.g. pseudomonas
What are aerobes?
Organisms that grow better with oxygen but can also grow without it e.g. staph, strep, enterococci and coliforms (i.e. majority of pathogens)
What is a strict anaerobe?
Organism that will NOT grow in the presence of oxygen e.g. Clostridium, bacteroides and anaerobic cocci
Present in large numbers in the large bowel
What organisms are present in the normal flora of the mouth?
Strep viridans, neisseria, candida
What organisms are present in the normal flora of the stomach/duodenum?
Usually sterile due to low pH - few candida and staph may survive
What organisms are present in the normal flora of the jejunum?
Small numbers of coliforms and anaerobes
What organisms are present in the normal flora of the colon?
Large numbers of coliforms, anaerobes and enterococcus faecalis
What organisms are present in the normal flora of the bile ducts?
Usually sterile
How is intra-abdominal sepsis treated?
Amoxicillin + gentamicin + metronidazole
What does amoxicilin cover?
Strep + enterococci (gram +ve)
What does gentamicin cover?
Aerobic coliforms (gram -ve)
What does metronidazole cover?
Anaerobes
How is intra-abdominal sepsis treated in a penicillin allergic patient?
Co-trimoxazole, gentamicin + metronidazole
Why is the duration of gentamicin treatment usually limited?
Concerns regarding nephrotoxicity
Usually limited to 72 hours and renal function is monitored daily
What is involved in SEPSIS 6?
BUFALO Blood cultures Urine output monitoring Fluid resuscitation Antibiotics IV Lactate and FBC Oxygen 15L/min
