Transcript How to prescribe antibiotics: maybe it’s not as simple as

Microbiology Nuts & Bolts
Test Yourself Session 3
Begin here
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The patient in this test yourself case is
entirely fictitious, however it is based
on many clinical scenarios the author
has come in to contact with during his
medical career. Any similarity to a real
case is entirely coincidental.
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Katie
• 23 year old student recently returned from
taking part in a voluntary project in Uganda
• She was fully vaccinated before her project and
took appropriate anti-malarial prophylaxis
• She developed diarrhoea 4 days after returning
to the UK and this has continued for the last 10
days
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Which of the following is unlikely to be
a travel related cause of this patients
diarrhoea?
Choose A, B, C or D for the answer you feel best
fits the question
A
B
C
D
Salmonella enteritidis
Norovirus
Giardia lamblia
Escherichia coli
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Correct
• Answer: Norovirus
• Whilst Norovirus is a common cause of diarrhoea the
incubation period is less than 2 days and the patients
symptoms occurred 4 days after her return. Therefore if
she has Norovirus it is unlikely to be related to her travel
history.
• Salmonella enteritidis is a common cause of
gastroenteritis in overseas travellers as well as those who
have not travelled.
• E. coli is the most common bacterial cause of travellers
diarrhoea, however it is rarely diagnosed because not only
is it a self-limiting infection, it is also impossible with
conventional laboratory methods to distinguish the
causative E. coli from all of the other normal E. coli in a
patients stool specimen
• Giardia lamblia is a parasitic cause of diarrhoea
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Katie
• Seen by her GP who thought she was
dehydrated despite trying to maintain her oral
fluid intake and so she was admitted to the local
hospital
• Infection control precautions were implemented
and she was started on IV fluids and IV
Ciprofloxacin for infectious diarrhoea
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What is the single most important
infection control precaution that
should be taken for this patient?
Choose A, B, C or D for the answer you feel best
fits the question
A
B
C
D
Source isolation
Barrier nursing
Protective isolation
Hand hygiene
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Correct
• Answer: Hand hygiene
• Hand hygiene is the single most important infection control
measure that can be taken, in this instance using soap and
water to wash your hands
• All other aspects are still important, Hand Hygiene is just the
most important!
• Source isolation involves placing a patient in a single room to
prevent try and reduce the potential for transmission of an
infection to others.
• Protective isolation involves placing a patient in a single room to
protect them from any infection others may have
• Barrier nursing is a descriptive term for using physical barriers
such as gloves, aprons and face masks whilst caring for patients
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Katie
• A stool sample was sent to the microbiology but
no clinical details were put on the request form
• Routine tests were done on the sample
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Which of the following organisms would
be looked for in a routine stool sample?
Choose A, B, C or D for the answer you feel best
fits the question
A
B
C
D
Vibrio cholerae
Clostridium difficile
Norovirus
Campylobacter spp.
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Correct
• Answer: Campylobacter spp.
• Routine laboratory tests are selected to detect the common
causes of a patients symptoms, in this case UK acquired
diarrhoea
• Campylobacter spp. Are the most common laboratory isolated
bacterial causes of gastroenteritis
• Travellers diarrhoea is a special circumstance and requires
extended investigations for organisms like parasites and Vibrio
cholerae – if the lab doesn’t know the patient has travelled these
organisms will not be looked for as it wastes time and money
• Not putting clinical information on a request cards means the
patient may not get the right test done AND the laboratory staff
are put at risk from potentially dangerous organisms
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Katie
• Katie’s stool culture grows Salmonella enteritidis
sensitive to Ciprofloxacin and Ceftriaxone
• She continues on IV fluids and IV Ciprofloxacin
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What is the correct treatment of
Salmonella enteritidis gastroenteritis?
Choose A, B, C or D for the answer you feel best
fits the question
A
B
C
D
Fluid resuscitation
Fluid resuscitation plus IV Ciprofloxacin
Fluid resuscitation plus oral Azithromycin
Oral Ciprofloxacin
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Correct
• Answer: Fluid resuscitation
• Almost all gastroenteritis is self limiting and only requires good
fluid intake
– The exceptions to this are:
• Typhoid and Paratyphoid
• Parasites
• Clostridium difficile
• Ciprofloxacin and Azithromycin can be used to treat Typhoid if
the organism is sensitive
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Katie
• 3 days in to admission Katie’s diarrhoea
becomes much worse
• She develops rigors, fevers and severe
abdominal pain
• She has bloods taken:
– White blood cell count 16x109/L
– C-reactive protein 237
• She is put nil-by-mouth
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What is the most likely cause of her
acute deterioration?
Choose A, B, C or D for the answer you feel best
fits the question
A
B
C
D
Allergy to Ciprofloxacin
Clostridium difficile associated diarrhoea
Worsening Salmonella gastroenteritis
Secondary Rotavirus infection
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Correct
• Answer: Clostridium difficile associated diarrhoea (CDAD)
• Acute gastrointestinal symptoms in any patient who is on
antibiotics or who has been on antibiotics within the last 30 days
should alert you to the possibility of CDAD
• This is a potentially life-threatening infection
• The patient needs urgent assessment and treatment
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Katie
• Katie is seen by a Junior Doctor who undertakes
a risk assessment for severity of Clostridium
difficile
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Which of the following is NOT a risk
factor for severe CDAD?
Choose A, B, C or D for the answer you feel best
fits the question
A
B
C
D
Age > 85 years
White Blood Cell Count > 15x109/L
Rising Creatinine
Abdominal pain
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Correct
• Answer: Abdominal pain
• Surprisingly abdominal pain is not a
marker of severity in CDAD
• The markers for potentially severe
CDAD are:
– Age >85 years
– WBC > 15 or < 1.5
– Rising creatinine
– Temperature > 38.5 oC
– Signs of colitis
– Colonic dilatation
– ICU admission
– Immunosuppression
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Katie
• The junior doctor implements a management
plan for CDAD whilst waiting for the results to
come back from the laboratory because they are
concerned about how unwell Katie is
• The plan includes:
–
–
–
–
–
Source isolation in a side room
Continued IV fluids
Oral Vancomycin for severe CDAD
Stop any proton pump inhibitors
Send a stool sample to the microbiology laboratory for
Clostridium difficile toxin testing
– Request for urgent senior and surgical reviews
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What else should the doctor do?
Choose A, B, C or D for the answer you feel best
fits the question
A
B
C
D
Initiate a Root Cause Analysis
Stop the Ciprofloxacin
Give the Vancomycin IV as patient nil-by-mouth
Give Loperamide
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Correct
• Answer: Stop the Ciprofloxacin
• Even though CDAD is caused by a bacteria, antibiotics do
predispose to the infection because they remove the normal
flora from the gut which allows C. difficile to take over
• Stopping the offending antimicrobial is crucial otherwise the
patient will continue to worsen
• IV vancomycin will not treat the patient as it doesn’t cross from
the blood stream in to the gut lumen and even if the patient is
nil-by-mouth they should still be given oral medication whenever
possible
• Loperamide to control diarrhoea is contra-indicated in CDAD
• Root cause analysis can wait!
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Katie
• Katie’s Ciprofloxacin is stopped but despite this
her condition deteriorates and she requires
surgery to repair a perforated bowel
• There is significant faecal peritonitis which
requires further antibiotic treatment
• The microbiologist is called to discuss
appropriate options so as to avoid any
antibiotics which could make her CDAD worse
• She is given IV Benzylpenicillin, Gentamicin and
Metronidazole in addition to her oral Vancomycin
as these will cover the peritonitis and yet be
relatively low risk for CDAD
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Which of the following is NOT one of
the 4 “Cs”?
Choose A, B, C or D for the answer you feel best
fits the question
A
B
C
D
Chloramphenicol
Clindamycin
Co-amoxiclav
Cefuroxime
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Correct
• Answer: Chloramphenicol
• The 4 “Cs” is an aide memoire to try and help you remember the
antibiotics which are highest risk for CDAD
• They are:
– Clindamycin
– Co-amoxiclav
– Ciprofloxacin (and the quinolones)
– Cephalosporins
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Katie
• A Root Cause Analysis is undertaken to try and
decide why this event occurred and whether
anything can be learnt to prevent it from
happening again
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What is the root cause for why this
patient developed CDAD?
Choose A, B, C or D for the answer you feel best
fits the question
A
B
C
D
Admission of the patient to hospital
Travel to Uganda
Use of IV rather than oral Ciprofloxacin
Incorrect gastroenteritis management
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Correct
• Answer: Incorrect gastroenteritis management
• RCA is the process by which the underlying reasons for an
event occurring are identified
• Katie should not have been given Ciprofloxacin for her
gastroenteritis
• She had no features of Typhoid or Paratyphoid and so
antibiotics were not indicated
• Common root causes for CDAD are:
– Inappropriate (or appropriate) choice of antibiotic e.g.
quinolones, clindamycin, cephalosporins
– Transmission of spores e.g. hand hygiene, environmental
cleaning
– Prolonged courses of antibiotics
– Multiple courses of antibiotics
– Failure to isolate suspected cases quickly enough
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Katie
• Following surgery Katie makes a slow recovery
and after 2 weeks of oral Vancomycin she is
eventually fit to go home
• Teaching was provided to the doctors about the
diagnosis and management of gastroenteritis as
part of the learning from the RCA
The End
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