Elderly Medicine Flashcards
1
Q
Why might a stool sample be useful in investigating GI infection?
A
- microscopy, culture & sensitivity
- clostridium difficile screening
- virology
- to look for ova, cysts and parasites
2
Q
When might abdominal USS and CT abdomen be performed when investigating GI infection?
A
Abdominal USS:
- this is the primary imaging technique when biliary infection is suspected
CT abdomen:
- this is the imaging technique of choice when other causes of intra-abdominal infection are suspected
- e.g. abscess, diverticulitis
3
Q
What are sterile site samples?
Why might these be performed?
A
- collection of fluid or tissue from deeper sources of infection
- MC&S of intra-abdominal fluid should be completed when possible to guide antimicrobial therapy
- samples are taken directly from the site of infection at the time of the intervention
- samples are more likely to represent the “true” pathogen
4
Q
What are drain samples?
What is the problem when interpreting these samples?
A
- involves taking fluid from drains that have been placed previously, typically from collecting bags
- results must be interpreted with caution as they may represent colonisation of the drain and not the “true” pathogen
- this is a non-sterile sample
5
Q
What would the diagnosis be in this scenario?
What antibiotics would be started?
A
- acute bacterial gastroenteritis - campylobacteriosis
- you would NOT want to start antibiotics as the patient is not in a high risk group
6
Q
After identifying a case of acute bacterial gastroenteritis in the patient who should be notified?
Does the patient need to be put into source isolation?
A
- PHE should be notified when any new case of food poisoning is found
- This could be a sporadic case or it could be part of an outbreak that you are unaware of
- the patient is from a long-term care facility and there may be potential implications in food handling at that premises
- it depends on local policy, but this patient will probably not be put into source isolation as direct person-to-person spread is rare, especially if the patient is continent
7
Q
What is the definition of acute gastroenteritis (food poisoning)?
What typically causes it and what accompanying symptoms may be present?
A
- an illness of < 14 days duration characterised by the presence of diarrhoea
- this means there are 3 or more loose stools per day or bloody stools
- accompanying symptoms may be abdominal pain / cramps, nausea, vomiting and fever
- typically a self-limiting illness
- it is usually caused by ingestion of food or water contaminated by GI flora
8
Q
What pathogens are associated with causing acute gastroenteritis?
A
- Campylobacter spp.
- Salmonella spp.
- Shigella spp.
- certain strands of E. coli, viral and protozoans
9
Q
What are the risk factors for acute gastroenteritis?
A
- increasing age > 60 or age < 5 years old
- eating raw or undercooked foods
- farmers or workers in the meat industry
- foreign travel
- eating out
10
Q
When is antibiotic treatment recommended for acute gastroenteritis?
A
- only for patients who can develop complications from acute gastroenteritis
- this includes pregnant women, those on immunosuppression therapy and those with symptoms lasting over a week
- most other patients have no adverse consequences and derive no benefit from antibiotic therapy, so treatment is NOT recommended
11
Q
How should acute gastroenteritis be reported?
What advice is given to patients?
A
- cases of infective gastroenteritis should be reported to PHE, particularly those involving food handlers
- highlight the importance of hand hygiene, food hygiene and disinfection of bedding
12
Q
What is the diagnosis?
How is this diagnosis made?
A
Clostridium difficile infection
- diagnosis is made by the presence of loose stools (type 5 - 7) and positive Clostridium difficile test or clinical suspicion while awaiting confirmatory tests
- things that raise clinical suspicion in this case:
- long course of ciprofloxacin
- description of the stools - green, slimy and offensive smelling
- accompanied with fever
13
Q
How would you confirm the presence of Clostridium difficile?
A
- take a stool sample for “Clostridium difficile testing”, which involves:
-
GDH (glutamate dehydrogenase) screen to determine if clostridia are present
- this does not tell you whether the clostridia present are producing toxins
- clostridia are present in many asymptomatic people
- cytotoxin assay to determine if toxin is actively being produced
- if both GDH screen and cytotoxin assay are positive, then clostridium difficile infection can be diagnosed
-
PCR for toxin genes may be performed to determine if toxin genes are present
- this shows the ability to produce toxin in the future, even if it is not currently being produced
- this patient might be at risk of future C diff diarrhoea so might want to consider rationing antibiotics
14
Q
What other investigations might be performed in someone with suspected C diff infection?
A
- FBC, U&Es, LFTs and lactate
-
abdominal X-ray and/or CT abdomen to look for colitis in more severe disease
- e.g. distension of the bowel or toxic megacolon
- these are only performed if there are abdominal clinical signs e.g. stomach cramps
15
Q
What factors predispose to developing C diff infection?
A
- old age (> 65 years)
- being in hospital
-
previous antimicrobial therapy
- especially 2nd (e.g. cefuroxime) and 3rd (e.g. cefotaxime) generation cephalosporins
- co-amoxiclav
- clindamycin
- quinolones (e.g. ciprofloxacin)
- long duration of antibiotic use (> 7 days)
- multiple antibiotic courses
- severe underlying disease
- presence of nasogastric tube
- non-surgical gastrointestinal procedures
- proton pump inhibitors
16
Q
What is involved in the non-antimicrobial management of someone with C diff infection?
A
- fluid resuscitation and electrolyte replacement as appropriate
- immediate instigation of isolation policy and clostridium difficile Infection Control Policy
- review ALL antimicrobials and any medicines that can produce diarrhoea
- record stool frequency and consistency daily on a Bristol Stool Chart
- daily monitoring for signs of increasing severity of disease
- review and stop PPIs if appropriate
- dietetic input and review in patients with a malnutrition universal screening tool score of 2 or more
17
Q
When should treatment for C diff infection be started?
What is involved in the antimicrobial management of C diff infection?
A
- treatment should be started if clinical suspicion is high, while awaiting toxin result
- the choice of antimicrobial depends on severity of disease, the number of co-morbidities and the number of episodes of CDI
- PO Vancomycin or PO Fidaxomicin are used
- PO metronidazole is less commonly used as it has been shown to be less effective
18
Q
What are the indications for using oral vancomycin?
Why is IV vancomycin usually used?
A
- it is only indicated in non-severe to life-threatening Clostridium difficile infection
- when given orally, it only works in the intestines and is NOT absorbed
- IV vancomycin is used to treat a variety of infections
19
Q
What is the mode of action of oral vancomycin?
A
it inhibits cell wall synthesis in gram positive bacteria
20
Q
What bacteria does oral vancomycin work on and why?
Do serum levels need to be monitored?
A
- it is not absorbed orally so it only works on bacteria that are present within the lumen of the intestines
- serum levels do not need to be monitored when given orally as it is not absorbed
21
Q
What pathogens is oral vancomycin active against?
What potential resistance exists?
A
- it can be active against Gram-positive organisms:
- clostridia
- staphylococci
- streptococci
- enterococci
- vancomycin resistant enterococci (VRE) are resistant to vancomycin
22
Q
What are the clinical indications for fidaxomicin?
What are the benefits to using this instead of vancomycin?
A
- indicated in mild to severe clostridium difficile infection
- when given orally it only works in the intestines and is NOT absorbed
- it is more expensive than vancomycin, but reduces the risk of recurrent CDI
23
Q
What is the mode of action of fidaxomicin?
What pathogens is it active against?
A
- it inhibits bacterial RNA polymerase
- it is only active against Clostridium difficile
24
Q
How does fidaxomicin work to treat CDI?
A
- it is not used to treat any other infections as it is poorly absorbed from the GI tract
- it kills Clostridium difficile within the intestinal lumen effectively with less disruption to the normal gut flora
25
What are the possible side effects associated with Fidaxomicin?
***_Allergy:_***
* rash, difficulty breathing, swelling of the face, lips, tongue or throat
***_GI side effects:_***
* nausea and vomiting
* constipation
26
What is meant by the "gut microbiome"?
What are its functions?
* the microbiome refers to the millions of **micro-organisms** that **live in and around the body**
* the gut microbiome is composed of trillions of bacteria that provide a **_physical barrier_** to more harmful bacteria
* they **compete for space and nutrients** which limit the potential for pathogenic bacteria to multiply
* functions of the gut microbiome include:
* aid **digestion**
* regulation of the **immune system**
* **_protection against infection_**
27
How can antibiotic use affect the gut microbiome?
* antibiotic use **_disrupts the gut microbiome_**, leading to a disbalance of bacteria populations
* this creates an ecological niche for **C. difficile spores to germinate**
28
Why is Fidaxomicin the preferred antibiotic to treat C. diff infection?
* it causes **less disruption** to the gut microbiome
* this means there is less capacity for C. difficile spores to germinate and produce **recurrent infection**
* this is known as **_colonisation resistance_**, which is provided by an intact gut microbiome
29
What is the diagnosis here?
How can you tell?
**_cholecystitis_**
* this is **inflammation of the gallbladder**
* diagnosis can be made from clinical signs:
* jaundice / scleral itcerus
* fever
* RUQ guarding / pain
* Murphy's sign positive
30
What is the difference between calculous and acalculous cholecystitis?
* **calculous cholecystitis** occurs as a result of **_cystic duct obstruction_** from **_cholelithiasis_**
* this is the presence of gallstones in the cystic duct
* **acalculous cholecystitis** does not involve gallstones
* it is less common and mainly seen in critically ill patients
31
What signs are typically present on examination of someone with cholecystitis?
How is the diagnosis confirmed?
* **_Murphy's sign_** will be positive
* this involves inspiratory arrest during RUQ palpation due to pain
* there will be **fever** and **RUQ guarding**
* diagnosis is made clinically but confirmed via **_ultrasound_**
* bloods will also show **deranged LFTs** in a **cholestatic pattern**
* **_raised bilirubin and ALP_**
32
How should patients with cholecystitis be investigated?
What does this typically show?
* FBC, LFTs, U&Es, CRP
* **blood culture** to identify the causative organism
* **ultrasound** will demonstrate **_duct dilatation_** and/or **_gallstones_**
* dilatation implies an obstruction further down the duct, causing it to dilate prior to the obstruction
33
What organisms typically are found to be causing cholecystitis?
* it is most commonly caused by **_Gram negative bacilli_** - especially ***E. coli***
* if there is an **_E. coli bacteraemia_** then consider a **_biliary source_** of infection
* **enterococci**, **streptococci** and **anaerobes** can also be found so empirical antibiotic management needs to cover all these organisms
34
How can you assess whether someone has had an allergic reaction to a beta lactam antibiotic?
* ***What antibiotics has the patient reacted to in the past?***
* ******decribe the nature of each reaction
* sometimes a patient will describe a side effect, rather than an allergic reaction
* ***When did the reaction take place?***
* ******how long after administration?
* type 1 reaction is immediate (\< 1 hour) and is typically mediated by penicillin specific IgE
* ***What is the nature of the reaction?***
* ******e.g. diarrhoea, rash, swelling, difficulties breathing
* ***If there is a rash, how can it be described?***
* ******e.g. maculopapular, pustular, bullous, urticarial
* ***Did the reaction resolve on cessation of antibiotics?***
35
How would you manage a patient who had a suspected penicillin allergy?
What antibiotic may they be given for cholecystitis?
* document the penicillin allergy IMMEDIATELY
* commence antibiotics based on blood culture results
* they may be given **_aztreonam_**, which has **purely Gram-negative cover**
* **_metronidazole_** is often given too as this has **anaerobe cover**
36
What would the diagnosis be in this situation?
Why would you be concerned about the recent MSU results?
**_complicated acute diverticulitis_**
* this is acute diverticulitis accompanied by an **abscess, fistula**, **bowel obstruction** or **perforation**
* there are **_2 MDR organisms_** in the urine, which indicates their **presence in the colon** of this patient
37
What other investigations would you want to perform in suspected acute complicated diverticulitis?
* blood cultures
* aspiration / drainage of the abscess
* review the history of UTIs and repeat MSU to see if the resistant organisms are still present
38
How would you treat the patient with complicated acute diverticulitis?
* ensure the patient is in source isolation as both ESBL and VRE are transmissible
* consider washout or aspiration of the abscess
* discuss with microbiology over the blood culture results to determine which antibiotic is most suitable
39
What is the difference in what you are looking for in a sterile sample compared to a non-sterile sample?
* in a **non-sterile sample**, such as a stool sample, you are looking for the presence of **_particular bacteria_**
* there will be lots of bacteria present, but you are looking for a particular organism
* when sampling a **sterile space**, the presence of **_any bacteria_** is significant as there should be **no bacteria** present here
40
What are the clinical indications for using tazocin (piperacillin / tazobactam)?
* complicated infections involving **GI, urinary, soft tissues** and **respiratory** (including COPD and HAP) systems
* **febrile neutropenia**
* it is a **_broad-spectrum_** antibiotic that has gram-positive, gram-negative and anaerobic cover
41
How does piperacillin/tazobactam work?
How is it given to patients?
* **piperacillin** inhibits the bacterial cell wall by **_binding PBP_**
* **tazobactam** **_inhibits B-lactamases_**, which prevents destruction of piperacillin
* it is **_only given IV_** and is widely distributed in tissues
42
What are the side effects of piperacillin/tazobactam?
What organisms is it effective against?
* the only side effect is **_diarrhoea_**
* it is active against **urinary pathogens**:
* Gram positive - staphylococci, streptococci, some enterococci
* Gram negative - proteus, E. coli, Klebsiella, pseudomonas
* anaerobes
* **resistance** is becoming more common in **_Gram negatives_** - **ESBLs / CPE**
43
What are the clinical indications for aztreonam?
How does it work?
* complicated infections involving **GI, respiratory, MSK** and **genito-urinary** systems
* it inhibits the bacterial cell wall by **_binding PBP_**
44
How is aztreonam given to patients?
Can it be used in penicillin allergy?
* it is available **_IV_**, but **not orally**
* it is widely distributed in tissues
* it is available in **nebulised form** for **chest suppression therapy in CF**
* it is **_safe to administer in penicillin allergy_** (caution in CF group)
* there is a small ris of cross reactivity with ceftazidime
45
What organisms is aztreonam effective against?
* it is active against **_Gram-negative organisms only_**
* e.g. proteus, E.coli, Klebsiella and Pseudomonas
* resistance is becoming more common - ESBL and CPE
46
What are the clinical indications for use of tigecycline?
How is this given to patients?
* complicated infections involving **_GI and skin/soft tissue_**
* it is **not a first line choice** and is not to be used if the patient is septic
* it is indicated in **_multiple resistances and/or allergies_**
* it is only **available IV** and is widely distributed in tissues
47
How does tigecycline work?
What caution is associated with using this antibiotic?
* it inhibits the bacterial 30S ribosomal subunit and inhibits protein synthesis
* it should be reserved for use in situations when alternative treatments are not suitable as clinical trials have shown possible increased mortality
48
What organisms is tigecycline effective against?
* it is active against urinary pathogens:
* Gram-postive - staphylococci, streptococci and enterococci
* Gram-negative - proteus, E. coli, Klebsiella
* anaerobes
* it is not active against pseudomonas
* it can be used against ESBL, VRE and MRSA
