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A2 ME3031 INFECTION > W07 - Clinical 1 - Diarrhoea, Outbreak, HIV, PUO > Flashcards

W07 - Clinical 1 - Diarrhoea, Outbreak, HIV, PUO Flashcards

1
Q

List the bacteria that are sought by routine culture of stools from patients with diarrhoea in the UK and outline their epidemiology.

A

CAMPYLOBACTER
C. jejuni (common), C. coli (less)

E. coli
enterotoxic (travellers diarrhoea

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2
Q

List other bacteria that cause diarrhoea, indicate the availability of routine tests for them & outline their epidemiology.

A

CAMPYLOBACTER

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3
Q

List the parasites commonly detected in stool specimens in the UK by microscopy and outline their epidemiology.

A

Protozoa, Helminths

*dx by microscopy; duodenal biopsy for trophozoites

Parasites, cysts, and ova request

  • Giardia duodenalis (cysts/trophozoites)
  • C parvum
  • diarrhoea, gas, malabs., failure to thrive

> METRONIDAZOLE (giarda)

*ENTAMOEBA HISTOLYTICA = amoebic dysentry / invasive (ab detection)
> METRONIDAZOLE + LUMINAL AGENT TO CLEAR COLONIZATION
*Liver abscess

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4
Q

List the viruses that commonly cause diarrhoea and outline their epidemiology and how they are detected.

A

SALMONELLA
S. enteritidis
S. typhimurium

*S. typhi / paratyphi = enteric fever (typhoid/paratyphoid) NOT gastroent.

  • rotavirus, Norovirus, Adenovirus
  • seasonal
  • ag detection in stool / PCR
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5
Q

Define food-poisoning, gastro-enteritis, dysentery and colitis.

A

GASTRO-ENTERITIS
3+ loose stooles/day + features

DYSENTERY
large bowel inflamm., bloody stools

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6
Q

Appreciate the normal bowel flora and the host’s natural defences against enteric
infections.

A

Cl. difficile diarrhoea - disruptions to normal gut flora

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7
Q

Understand the epidemiology of bacterial and viral gastro-enteritis.

A

Contaminated foodstuffs; intensive farming - CAMPYLOBACTER (commonest bact.)

Travel - SALMONELLA

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8
Q

The mechanisms by which infecting organisms can produce diarrhoea - toxin mediated, invasion, attachment

A

NON-INFLAMMATORY (toxin-med)
-Cholera: toxin retrograde endocytosis = ⇧cAMP and Cl secretion

  • ENTEROTOXIGENIC E. COLI (traveller’s)
  • frequent watery stools

INFLAMMATORY
- toxin dmg and mucosal destruction = pain & fever

*bact. infection/amoebic dysentry

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9
Q

Outline the principles of managing gastro-enteritis - history taking, assessing
dehydration,

A

> Rehydration therapy essential +/- Abx

> Salt/sugar solution (NaCl, KCl, Glucose)
* SGLT1 co-transporter; GLUT2; draws water in

  • 2w = unlikely to be infective fastro-enteritis
  • ?risk of food poisoning
  • Hydration = postural BP, skin turgor, pulse
  • Inflamm = fever, raised WCC

!Hyponatraemia; Hypokalaemia

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10
Q

Describe the potential complications of E. coli O157 infection.

A

Haemolytic-uraemic syndrome (shiga toxin in blood) = haemolytic anaemia and RenFailure; thrombocytopoenia; shistocytes

  • freq bloody stools
  • Seizures
  • microangiopathy

> Supportive Tx only

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11
Q

Investigations of patient

A

Stool culture +/- molecular/Ag testing

Blood culture

Renal function

Blood count = haemlysis with E Coli O157

XR/CT with abdo distension

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12
Q

Diff. Dx to gastroent.

A

IBD
Spurious diarrhoea - 2º to constipation
Carcinoma

Nil abdo pain/tenderness = not gastroenteritis

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13
Q

Campylobacter gastroent. features

A

7d incubation; dietary hx may be unreliable

Abdo pain

Post-infection sequelae = Guillain-Barre sndrome, Reactive Arthritis

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14
Q

Salmonella gastroent. features

A

<48hr post-exposure onset; quicker
<10d diarrhoea

  • +ve stooled at 20w (20% of patients - ?gallstones)
  • post-infectious irritable bowel common
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15
Q

Abx indications

A

Gastroent:

  • imm compr.
  • severe sepsis/invasive infection
  • chronic illness e.g. malignancy
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16
Q

Significance of Abx use and C diff diarrhoea

A

‘4 C’s’ (clindamycin, cephalosporins, co-amoxiclav and ciprofloxacin) associated with a higher risk of C. difficile infection. Often two or more antibiotics are prescribed at the same time and in the case of osteomyelitis for a minimum course of 4–6 weeks

  • severe colitis
  • enterotoxin A & cytotoxin B

> Metronidazole
Oral vancomycin
Stool transplants
Fidaxomicin

17
Q

Difference between Non-inflamm Vs Inflamm

A

Non-inflammatory:

  • Toxin-mediated usually
  • Watery stools, rapid dehydration, relatively little abdo pain
  • Rehydration mainstay of treatment

Inflammatory:

  • Bacterial infection usually
  • Abdo pain, bloody stools, sytemic upset
  • Rehydration and (sometimes) antimicrobials required
18
Q

Definition of confirmed, probable, possible cases

A

Confirmed – patient has predetermined signs and symptoms or positive lab test

Probable - patient has predetermined signs and symptoms or close contact

Possible – patient has one or few predetermined signs and symptoms

19
Q

Criteria to declare a COVID-19 cluster/incident in an inpatient setting

A

Two or more patient and/or staff cases of COVID-19 within a specific setting where nosocomial infection and ongoing transmission is suspected

20
Q

Outline the basic virological features of HIV.

A

CD4+ destruction = TH, macrophages, monocytes, cells in the brain, skin

• ⇧HIV viral load ⇩CD4 count

  • ⇧risk of developing infection esp as CD4 declines
  • AIDS dx occur at CD4 <200

=> Symptomatic HIV infection = viral load > CD4
+ opportunistic infection

21
Q

Describe the modes of transmission and epidemiology of HIV infection

A
  • sexual transmission
  • injection/drug misuse
  • blood products
  • vertical transmission
  • organ transplant
22
Q

Describe the clinical presentations of HIV infection.

A

Pt wt. loss, lymphadenoapthy, thrush, skin and oral disease

  • acute infection = seroconversion
  • HIV infection = asymptomatic
  • HIV related illness
  • AIDS = symptomatic infection/tumour

1) asymptomatic
+ PERSISTENT GENERALISED LYMPHADENOPATHY

2) WT LOSS <10% OF BODY WEIGHT
+mucocutaenous manifestations (seborrheic dermatitis, prurigo, fungal nai infections, oral ulcerations)

+ Herpes zoster
+ recurrent URT infections
symptomatic but normal activity

3) WT LOSS >10% of BODY WT.
chronic diarrhoea >1mos
prolonged fever >1mos
oral candidiasis; oral leuoplakia, pulmonary TB

bedridden (performance scale 3)

4) HIV wasting syndrome
• pneumocystic carinii pneumonia
• toxoplasmosis of brain
• HSV >1mos
• Kaposi's sarcoma
disseminated.

performance scale 4

23
Q

List the laboratory tests used to diagnose HIV infection & describe the clinical significance of viral load measurement

A

POC = blood sample finger prick

24
Q

Describe laboratory and clinical monitoring of HIV disease.

A

Monitoring HIV Ag and HIV Ab

HIV viral load used to monitor efficacy of ART

Viral nucleic acid used to dx in babies via vertical transmission

25
Q

Describe the current treatment of HIV infection with anti viral agents.

A

antivirals for AIDS illness = return back to HIV infection state

> PrEP
PEP for Sexual Exposure

> ART - combination pill (cART)

req. 90% adherence
- poor adherence = viral mutation and adherence

*NUCLEOSIDE: reverse transcriptase
!marrow tox., neuropathy, lipodystrophy

*NON-NUCLEOSIDE: reverse transcriptase
!skin rashes, hypersens, drug interactions

*PROTEASE inhibitors
!drug-drug, diarrhoea, lipodystrophy, hyperlipidaemia

*INTEGRASE inhib.
!rashes, disrupted sleep

  • start all pt. at dx
  • lifetime
26
Q

Describe the ethical issues involved in HIV testing

A

1) Sensitivity
2) Informed Consent -
3) Confidentiality balance with possible risk to others
4) Patients may request their status is hidden from other practice staff

27
Q

List the infections which may be transmitted by needlestick injuries.

A

HIV

Hep B, Hep C

28
Q

Outline the recommended procedure following a needlestick injury.

A
  • Wash off splashes on skin with soap and running water.
  • Encourage bleeding if the skin has been broken, but do not suck.
  • Wash out splashes in the eye, nose or mouth.
  • Assessment of the risk of virus transmission by someone other than the victim.
  • Report the incident.
29
Q

Signficance of 1º HIV / seroconversion

A

abrupt onset 2-4w post exposure; self-limiting

non-specific

Flu-like illness
Fever
malaise lethargy

30
Q

Signficance of Pneumocystis jiroveci pneumonia

A

Commonest late stage AID infection
CD4 <200

Classical history of dry cough and increasing breathlessness over seveal weeks

-CXR, sputum, broncoscopy

> COTRIMOXAZOLE
PENTAMIDINE

31
Q

Define PUO

A

temperature of greater than 38.3oC on multiple occasions during a period longer than three weeks that defied one week’s evaluation of the patient in hospital
• 3 outpatient/inpatient +
• 1 week of outpatient investigation

+Nonsocomial

+Neuropenic - fever w/ neutrophil <500 undiagnosed after 3 days of investigation

+HIV-associated PUO - 3days inpatient / 4w outpatient

32
Q

List the major disease categories which can present with a PUO.

A

INFECTION

MALIGNANCY

INFLAMMATORY

33
Q

Outline the approach to the PUO patient - important aspects of history taking, examination and preliminary investigations.

A

urines, fbcs, CRP AND ESR (acute phase reactants), blood cultures

34
Q

Appreciate some of the contemporary imaging techniques available for use in investigating PUO.

A

CXR
Echocadiography (new murmur)
CT PET

  • cannot always differentiate between infection and inflamm
  • anatomical change may not develop in imm compr.
35
Q

Understand the place of the “therapeutic trial” in PUO patients.

A

Suspected myobacterial infection

suspected vasculitis or connective tissue disorder

36
Q

Common causes of HIV-PUO

A

Mycobacterium tuberculosis
Mycobacterium avium
Mix of causatives
Unknown

37
Q

Next stage of investigating PUO

A

Invasive investigations

  • tissue culture and histology
  • BM, liver = blind investigation
38
Q

Outcomes of PUO

A

Spontaneous resolution (younger more common)

Alternatively respond to NSAIDs or steroids

A2 ME3031 INFECTION (4 decks)

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