Week 4/5 - A - Gastroenteritis (C.Diff, rotavirus (children), norovirus (winter vomiting)), peritonitis/intra-abdo sepsis/sepsis

Question 1

Define colonisation? Define pathogen? What is virulence?

Answer 1

Colonisation is the establishment of a microorganism on or within a host without inflammation A pathogen is any microorganism that has the potential to cause disease Virulence is the degree of pathogenicity - the likelihood of a pathogen causing disease

Question 2

Define infection? Define bactaraemia? (septicaemia term no longer used) Define sepsis? What can this lead to?

Answer 2

Infection Inflammation due to a microbe Bacteraemia The presence of viable bacteria in the blood Sepsis is an overwhelming and life-threatening inflammatory response to a severe infection * It can lead to tissue damage, and organ failure –> Septic shock * and eventually death

Question 3

* Can classify bacterial organisms as gram positive/negative * Can classify based on shape * Clan classify based on growth characteristic - aerobic or anaerobic What are the different shapes? - give an example

Answer 3

Bacilli - gram negative bacilli eg enterobacteriaceae - includes the coliforms Coccus - gram positive cocci eg streptococci (chains) / staphylococci (clusters) Gram negative (diplo)cocci - eg neisseria meningitidis / gonorrhoea Spirochete - gram negative spirochete eg helicobacter pylori

Question 4

What is the normal bacteria flora of the mouth?

Answer 4

Examples of normal flora of mouth Strep viridans (alpha haemolytic strep) Neisseria sp (gram negative diplococci) Candida

Question 5

What are examples of normal flora of stomach/duodenum?

Answer 5

Stomach/duodenum is usually sterile as it has a low pH Few candida and staphylococci and lactobacillia may survive

Question 6

What is the normal flow of the jejunum? What is the normal flow of the colon?

Answer 6

Jejunum - small numbers of coliforms and anaerobes Colon (faecal flora) 0 large numbers of coliforms, anaerobes (clostridium species), enterococcus faecalis

Question 7

What is an aerobic bacteria? What is a strict aerobe? (give an example?

Answer 7

Aerobic organismms - Organisms that grow better with oxygen, but can also grow without it, e.g. staphylococci, streptococci, enterococci and coliforms (i.e.the majority of human pathogens) Strict aerobe - organisms that require oxygen for growth * eg pseudomonas or legionella * (both gram negative strict aerobic bacilla)

Question 8

What is a strict anaerobic bacteria? Give an example of a gram positive and gram negative species of anaerobic bacteria and wher they are present?

Answer 8

* A strict anaerobic bacteria is one that will not grow in the presence of oxygen - they are presen in large numbers in the large bowel Gram positive anaerobic bacilli * Clostridium species * Tetani - tetanus * Perfringes - gas gangreen * Difficle - antibiotic associated colitis * Botulinum - botullism Gram negative aenarobic bacilli - Bacteroides

Question 9

What are the different common things that increase the risk of GI infections in the community?

Answer 9

Cross contamination work surfaces/utensils Undercooking (insufficient heat to kill of pathogens), linked to inadequate defrosting of frozen food Improper storage of food (inadequate refrigeration) Poor reheating of food

Question 10

When is a patient with a GI infection most infectious? If a staff member develops diarrhoea, how long should you stay off work?

Answer 10

patients at their most infectious when symptomatic with diarrhoea If you develop diarrhoea that is probably infectious, STAY OFF WORK until 48 hours after symptoms have stopped (special leave)

Question 11

What is the most common healthcare-associated diarrhea? - also known as antibiotic associated colitis Is it part of the normal colonic flora?

Answer 11

Clostridium difficile (C. Diff) is the most common healthcare associated diarrhoea It is carried as part of the normal colonic flora in partiular in elderly and infants

Question 12

When does clostridium difficile infection develop? What is the mechanism of the disease?

Answer 12

Clostridium difficile infection develops when antibiotics that are prescribed kill off or suppres the normal competitive gut flora which allows C diff to overgow The organsims produces 2 exotoxins - toxin A (enterotoxin- toxic to the bowel) and toxin B (cytotoxin - toxic to other cells) These toxins cause colitis. C diff also produces spores which are more resistant to disinfectants and allows transfer of organism from one patient to another

Question 13

What type of bacteria is C.diff? What drugs cause an increased risk of C.difficile infection?

Answer 13

C.diff is a gram positive anaerobic bacilli 4C antibiotics * Clindamycin * Co-amoxiclav (amoxicillin + clavulanic acid) * Ciprofloxacin - and other quinolones * Cephalosporins Also PPIs increase the risk Also enteral feeds increase the risk

Question 14

What are the symptoms of a C.diff infection? What may be seen on endoscopy in severe cases?

Answer 14

Watery diarrhoea - sometimes bloody Abdominal pain Raised white cell count Severe cases may cause pseudomembranous colitis - viscious collection of inflammatory cells, fibrin cells and necrotic cells

Question 15

There is no one good lab test for C.diff How is it diagnosed?

Answer 15

Screening test - stool immunoassay for glutamate dehydrogenase (common antigen indicating presence of the organism) If GDH positive, then need to test for presence of toxin (Toxin A&B) Stool toxin test (toxin immunoassay, toxin PCR) - confirms infection from colonoisation

Question 16

What can severe cases of C.difficile cause to the bowel?

Answer 16

* Ileus * Colonic dilatation >6cm on AXR/CT, * Toxic megacolon (colon to expand, dilate, and distend. When this happens, the colon is unable to remove gas or feces from the body. If gas and feces build up in the colon, your large intestine may eventually rupture) and * /or pseudomembranous colitis

Question 17

What is given for the management of C.diff? (non-severe, severe, recurrent)

Answer 17

Non-severe infection - oral metonidazole Severe infection - oral vancomycin Severe non responder eg due to ileus - give vancomycin and IV metronidazole If recurrent infection - can give oral fidomaxicin

Question 18

When is a patient considered to be clear of the C-diff infection? How do you stop the spread of C.diff? (mnemonic = SIGHT)

Answer 18

Patient considered to be clear after 48 hours symptom free Stop spread - SIGHT * Suspect * Isolate patients within 2 hours * Gloves and aprons * Hand washing with soap (not alcohol) * Test immediately

Question 19

What is the commonest cause of diarrhoea and vomiting in children? (under 3 years) By what age have most children had this infection?

Answer 19

Rotavirus is the commonest cause of diarrhoea and vomiting in children <3years Most children have had the infection by age 5

Question 20

How long does the symptoms of rotavirus last? Is there any blood? What are other symptom? How is it diagnosed?

Answer 20

Rotavirus symptoms of diarrhoea and vomiting usually last around one week There is NO blood int he diarrhoea Other symptoms include a fever and abdominal pain Diagnosis is confirmed by stool viral PCR

Question 21

What is the treatment of rotavirus? When is the vaccination programme for this virus?

Answer 21

Treatment of rotavrius is supportive - rehydration is key Rotavrius vaccine is a live attenuated vaccine given to children Given at 8 weeks and 12 weeks

Question 22

Is rotavrius a single or double stranded RNA virus? What is the virus that causes the winter-vomiting bug? Is this a single or double stranded RNA virus?

Answer 22

Rotavrius is a double stranded RNA virus Norovirus is a single stranded RNA virus that causes the winter vomiting bug - although lately it has been all year round

Question 23

What is the transmission of both rotavirus and norovirus?

Answer 23

Rotavirus is spread by * faecal oral route and * respiratory transmission Norovirus is spread by * faecal oral route * person to person spread * contaminated food/water

Question 24

What is the incubation period of both rotavirus and norovirus?

Answer 24

Incubation period for rotavirus is approx 2 days Incubation period for norovirus is short - normally less than 24 hours

Question 25

What are the symptoms of norovirus and how long do they last?

Answer 25

Sudden explosive diarrhoea and vomiting, lasting 2-4days Vomiting leads to widespread contamination of the environment –> outbreaks Associated symptoms include headache and fever

Question 26

Both rotavirus and noravirus shed in the stool How long does norovirus shed continue up to in asymptomatic patients post-cessation of symptoms? How is norovirus diagnosed?

Answer 26

Asymptomatic shedding occurs for up to 48 hours post cessation of symptoms Diagnosis is viral PCR tests on stool specimen or vomit swab

Question 27

What is the treatment of norovirus?

Answer 27

The infection is self-limiting in immunocompetent patients and symptoms generally resolve within 72 hours Dehydration and electrolyte imbalances may arise as a result of vomiting and diarrhoea, leading to significant morbidity and mortality and patients should be managed supportively with rehydration and electrolyte supplementation where necessary.

Question 28

INTRA ABDOMINAL SEPSIS Peritoneal cavity is normally sterile. Leakage of the bowel contents results in peritonitis What can cause leakage into the peritoneal cavity?

Answer 28

examples Perforated duodenal ulcer Perforated appendix Perforated diverticulum Perforated tumour

Question 29

What are the local and systemic signs of peritonitis?

Answer 29

Local signs * Pain, tenderness, guarding, PR blood in some Systemic * Fever * Chills / rigors * Nausea and omiting * Consitpation or diarrhoea * Prostration * Shock

Question 30

How is peritonitis diagnosed?

Answer 30

A diagnosis of peritonitis is based primarily on the clinical manifestations AXR may reveal dilated, edematous intestines, although such X-rays are mainly useful to look for gas under the diaphragm -> pneumoperitoneum, an indicator of gastrointestinal perforation.

Question 31

What is the antibiotic treatment of peritonitis/biliary tract infection/intra-abdominal sepsis? Usually for peritonitis, surgical procedure may have to be carried out to repair if eg a perforation

Answer 31

IV Amoxicillin + Metronidazole + Gentamicin * Step down: PO Co-trimoxazole + Metronidazole If pen allergic: IV Vancomycin + Metronidazole + Gentamicin * Step down: PO Co-trimoxazole + Metronidazole Amoxicillin –> (streptococci & enteroccoci) Metronidazole –> (anaerobes) Gentamicin –> (coliforms)

Question 32

What are examples of coliforms? Micro-organisms leaked into the peritoneal cavity will form abscesses (pus cells and organisms) How are these treated?

Answer 32

Coliform examples - gram negative bacilli * Escherichia coli (E.coli) * Klebsiella * Proteus * Enterobacter * Serratia Small abscesses can be treated with antibiotics but large collections need incision and drainage A large abscess has no blood supply and so antibiotics will not penetrate it well

Question 33

The qSOFA (Quick SOFA - sequential organ failure assessment score) Score for Sepsis identifies high-risk patients for in-hospital mortality with suspected infection outside the ICU. (mortality predictor, not diagnostic for sepsis) What are the three things measured in qSOFA to predict the patients mortality? What score indicates a high risk prediction?

Answer 33

Adult patients outside of ICU with suspected infection are identified as being at heightened risk of mortality if they have quickSOFA (qSOFA) score meeting >= 2 of the following criteria * RR >/= 22bpm * SBP qSOFA >/=2 -> think sepsis

Question 34

Image shows disease continuum –> * Colonisation * Infection * SIRS * Sepsis * Septic shock What is SIRS? What is needed for a SIRS classification?

Answer 34

SIRS - systemic inflammatory response syndrome A non-specific response including >/=2 of the following * Temp >38 degrees or 90 bpm * Resp rate >20/min * WBC count >12,000/mm3 or 12 or

Question 35

What is SEPSIS defined as?

Answer 35

Sepsis is defined as * SIRS with a presumed or confirmed infectious process * or * NEWS >/5 and infection

Question 36

What is septic shock?

Answer 36

Septic shock is defined as sepsis plus sign of at least one acute organ dysfunction Septic shock is also hypotension refractory to adequate volume resuscitation -> SBP 40mmHg from normal

Question 37

Septic shock * Renal * Resp * Hepatic * Haematological eg DIC * CNS * Unexplained metabolic acidosis * Cardiovascular –> hypotnesion State different indicators of severe organ damage? - ie the tests that would show this

Answer 37

* Renal - urine output 1.5) * Cardiovascular - SBP 40mmHg drop from normal

Question 38

Within one hour of thinking sepsis, the sepsis 6 bundle must be started What is given here?

Answer 38

BUFALO * Blood cultures - and other cultures, urine, wound swabs * Urine output - catheterise and monitor hourly output * Fluids - IV fluids 500mls crystalloid STAT (within 15 minutes) * Antibiotics - IV antibiotics * Lactate and FBC * Oxygen - high flow Order may be * O2, Fluid, Blood cultures, Abx, Lactate/FBC, Urine

Question 39

Which antibiotics are given for the empirical treatment of sepsis?

Answer 39

IV amoxicillin, metronidazole and gentamicin

Question 40

Septic shock can also be defined based on the lactate levels and MAP How does NICE define sepsis based on these?

Answer 40

Septic shock can be defined as sepsis with * persisting hypotension despite fluid correction and inotropes (requiring vasopressors to maintain a mean arterial pressure [MAP] of 65 mmHg or more), * and hyperlactataemia with a serum lactate level of greater than 2 mmol/L

(if lactate level >4, mortality rate of 38%)