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Microbiology Nuts & BoltsTest Yourself - Gastrointestinal

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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.


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


Which of the following is unlikely to be a travel related cause of this patients

diarrhoea?

Salmonella enteritidisNorovirusGiardia lambliaEscherichia coli

ABCD

Choose A, B, C or D for the answer you feel best fits the question


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


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


What is the single most important infection control precaution that should be taken for this patient?

Source isolationBarrier nursingProtective isolationHand hygiene

A

BC

D



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


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


Which of the following organisms would be looked for in a routine stool sample?

Vibrio choleraeClostridium difficileNorovirusCampylobacter spp.

AB

CD



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


Katie• Katie’s stool culture grows Salmonella enteritidis

sensitive to Ciprofloxacin and Ceftriaxone• She continues on IV fluids and IV Ciprofloxacin


What is the correct treatment of Salmonella enteritidis gastroenteritis?

Fluid resuscitationFluid resuscitation plus IV CiprofloxacinFluid resuscitation plus oral AzithromycinOral Ciprofloxacin

ABC

D



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


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


What is the most likely cause of her acute deterioration?

Allergy to CiprofloxacinClostridium difficile associated diarrhoeaWorsening Salmonella gastroenteritisSecondary Rotavirus infection

ABCD



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


Katie• Katie is seen by a Junior Doctor who undertakes

a risk assessment for severity of Clostridium difficile


Which of the following is NOT a risk factor for severe CDAD?

Age > 85 yearsWhite Blood Cell Count > 15x109/LRising CreatinineAbdominal pain

ABC

D



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


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


What else should the doctor do?

Initiate a Root Cause AnalysisStop the CiprofloxacinGive the Vancomycin IV as patient nil-by-mouthGive Loperamide

ABC

D



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!


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


Which of the following is NOT one of the 4 “Cs”?

ChloramphenicolClindamycinCo-amoxiclavCefuroxime

ABC

D



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


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


What is the root cause for why this patient developed CDAD?

Admission of the patient to hospitalTravel to UgandaUse of IV rather than oral CiprofloxacinIncorrect gastroenteritis management

ABC

D



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


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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infectious diarrhoea

patients diarrhoea

common cause of diarrhoea

hand hygiene hand hygiene

travel related cause

correct answer

single room