Infection Summary Flashcards
(93 cards)
1
Q
Gastroenteritis Presentation
A
vomiting and diarrhoea (3 or more loose stools a day), + abdominal pain/discomfort (can be quite severe if campylobacter), fever,
bloods in stool can be indicative of a bacterial infection
signs of dehydration:
thirsty, dry mucous membranes: mild, (<5% weight loss)
lethargic, reduced skin turgor, sunken eyes, sunken anterior fontanelle, tachycardia, reduced urine output, reduced tears: moderate (5-10% weight loss)
drowsy, absent urine output, prolonged capillary refill time, weak pulse, low BP (signs of hypovolaemic shock): severe (>10% weight loss)
2
Q
Gastroenteritis Investigation / diagnosis
A
stool MC&S, urea and electrolytes
3
Q
Gastroenteritis Management
A
oral rehydration therapy given frequently in small amounts; IV fluids if not tolerating oral/nasogastric fluids. Good handwashing to prevent spread. Notify public health if bacterial
4
Q
Complications of campylobacter infection
A
Guillain-Barre
Reactive arthritis
5
Q
What can predispose you to gastroenteritis?
A
HIV
Omeprazole
6
Q
Presentation of CDIFF
A
mild diarrhoea to severe colitis
diarrhoea, fever, abdominal pain
7
Q
Investigations for CDIFF
A
stools MC&S, FBC (increased WCC)
8
Q
Treatment for C. Diff
A
metronidazole (first line), stool transplant, oral vancomycin (second line), fidaxomicin, surgery may be required, isolation, barrier nursing
prevention: stop AB (cephalosporin, clarithromycin, clindamycin, co-amoxiclav)
9
Q
What are the complications of C.Diff?
A
pseudomembranous colitis, toxic megacolon, sepsis
10
Q
What are the toxins that c.diff produces?
A
A (enterotoxin) and B (cytotoxin)
11
Q
Presentation of infectious diarrhoea
A
fever, diarrhoea (may be bloody), nausea, dehydration, abdominal pain, bloody diarrhoea is more common with Campylobacter, Shigella
12
Q
What is the diagnosis of infectious diarrhoea?
A
diagnosis by antigen detection
FBC, U&E, CRP, stool microscopy, culture and sensitivity (MC&S), blood cultures if septic
13
Q
What is the management of infectious diarrhoea?
A
majority of cases are self-terminating and require rehydration and electrolyte correction: AB are considered in immunocompromised patients, the very young or the very septic; always liaise with microbiologists
14
Q
What viruses can cause infectious diarrhoea?
A
adenovirus, rotavirus in children under 5 years
15
Q
What are the complications of infectous diarrhoea?
A
renal failure, septic shock; E. coli is associated with the haemolytic-uraemic syndrome
16
Q
What are the symptoms / presentation for giardia lamblia?
A
diarrhoea, malabsorption, failure to thrive
17
Q
What is the investagation for giardia lamblia?
A
Cysts seen on stool microscopy
18
Q
What is the treatment for giardia lamblia?
A
Metronidazole
19
Q
How is giardia lamblia spread?
A
Contaminated water
20
Q
Whet type of organism is giardia lamblia?
A
Parasite
21
Q
What bacterium causes the majority of cases of travellers diarrhoea in developing countries?
A
Enterotoxigenic e.coli
22
Q
What is the normal reservoir of Ecoli o157 (this is an enterohaemorrhagic bacterium)
A
2.5% of britich cattle secrete VTEC (verotoxin producing Ecoli)
The reservoir of infectio nis in the gut of herbivores.
The organism has an ectremely low infecting dose.
23
Q
What are the symptoms of enterohaemorrhagi bacteria?
A
Initial watery diarrhoea
Becomes blood stained in 70% of cases. Associated with severe and often constant abdominal pain.
Little systemic upset, vomittin or fever.
24
Q
What is the complication associated with Ecoli o157?
A
HUS
Haemolytic Uraemic syndrome
25
Who is affected by HUS?
HUS affects 10-15% of sufferers from this infection
Arises 5-7 days after the onset of symptoms
Most likely i nthe extremes of age, heralded by a high peripheral leucocyte count and may be induced particularly in chgildren by antibiotic therapy
26
What is the treatment for HUS?
Dialysis if necessary and may be averted by plasma exchange
Antibiotics should be avoided since they can stimulate toxin release.
27
What cells does the HIV virus attack?
Attacks the CD4 cells (T helper cells, macrophages and dendritic cells)
28
What are the features of the primary infection of HIV?
Usually symptomatic in more than 50% of cases
Incubation period is 2-4 weeks after exposure
Clinical features resemble a glandular fever type of illness (flu like symptoms - (presence of maculopapular rash and oral ulceration strongly suggests primary HIV infection rather than other viral casues of glandular fever.)
29
What is the progression of HIV after the primary infection?
Chronic phase which can last 2-10 years.
Depletion of CD4 cells and increase viral load
Clinical latelcy follows primary infection - individuals are asymptomatic.
Persistent lymphadenopathy less than 2cm diameter ius a common finding.
30
What is the differential diagnosis for primary HIV?
EBV
Primary cytomegalovirus infection
Rubella
Primary toxoplasmosis
Secondary syphilis
31
When does HIV become AIDS?
The development of specified opportunistic infections cancers and severe manifestations of HIV itself.
Can be diagnosed by having a CD4 count that is less than 200/mm3
CDC is the most used category of AIDS defining illnesses
32
CDC category A for HIV
Primary HIV infection
Asymptomatic
Persistent generalised lymphadenopathy
33
CDC category B for HIV
Candidiasis (oropharyngeal)
Fever / diarrhoea lasting for over one month
Oral hairy leucoplakia
Cervial dysplasia / carcinoma in situ
Idiopathic thrombocytopenic purpura
Peripheral neurupathy
34
CDC category C for HIV infection
Candidiasis of trachea, bronchi or lungs
Cervical carcinoma that is invasive
Cryptococcosis - extrapulmonary
Cytomegalovirus disease (outside the liver spleen and nodes)
Herpes simplex chronic ulcers or visceral
HIV encephalopathy
Kaposi's sarcoma
Lymphoma (cerebral or B cell non hodgkin)
Pneumocystis pneumonia
Recurrent bacterial pneumonia
Cerebral toxoplasmosis
Tuberculosis
35
How is viral load determined?
Quantitive PCR of HIV - RNA
36
How is HIV diagnosed?
By detectiong host antibodies (either by point of care tests or by ELISA)
A positive antibody test from two different immunoasays is sufficiennt to confirm infection
Screening may involve testing for p24 antigen in addition to antibodies (incase antibody production hasn't started yet)
Nucleic acid amplification (usually PCR) of HIV-RNA is carried out on children who's mothers have had AIDS (the maternal antibodies will live in their system for 15 months and they might not have produced their own antibodies yet).
37
What are the aims of ART?
Reduce the viral load to an undetectable level for as long as possible
Improve CD4 count to over 200 cells/mm3 so that severe HIV-related disease is unlikely
Improve the quality of life without unacceptable drug toxicity
Reduce HIV transmission
38
What are the classes of antiretroviral drugs?
Nucleoside reverse transcriptase inhibitors (NRTIs)
Non-nucleoside reverse transcriptase inhibitors (NNRIS)
Protease inhibitors
Integrase inhibitors
Chemokine receptor inhibitor
39
Give examples for each type of ART
NRTI - abacavir, zidovudine
NNRTI - Efavirenz
PI - Atazanavir
Integrase inhibitors = Raltegravir
Chemokine receptor inhibitor = maraviroc
40
What is the standard antiretroviral regimen?
Two NRTI's together
NNRTI
Protease inhibitor
or Integrase inhibitor
Most guidelines from high-income countries allow clonicians to choose a starting regimen of dual NRTIs combined with an NNRTI, or a PI or integrase inhibitor as these three regimens have a similar efficacy.
41
What must PI's be co-prescribed with?
Must be co-prescribed with ritonavir - low doses oof ritonavir dramatically increase the concentrations and elimination half-lives of other PI's by inhibitin gtheir metabolism by cytochroime P450. This increases drug exposure, reducing pill burden and dosing frequency - optimising adherence
42
When should ART therapy begin?
ART therapy should begin in adults when CD4 count falls below 350 cells / mm or clinical stage 3/4
43
Lymes Disease Presentation:
early: erythema chronicum migrans + systemic features (fever, arthralgia)
CVS: heart block, myocarditis
neuro: cranial nerve palsies, meningitis
44
What causes Lymes disease
Spirochaete Borrelia Burgdorferi
45
What is the investigation for Lymes disease?
NICE recommend that Lyme disease can be diagnosed clinically if erythema migrans is present
enzyme-linked immunosorbent assay (ELISA) antibodies to Borrelia burgdorferi are the first-line test
if this test is positive or equivocal then an immunoblot test for Lyme disease should be done
46
What are later complications of Lyme Disease?
Acrodermatitis chronica atroficans (ACA) - this is atrophy of the skin, often has involvement of the peripheral nervous system causing polyneuropathy
Lymphocytoma can also be caused (also chronic)
neuroborreliosis
47
What is the management of asymptomatic tick bites?
tick bites can be a relatively common presentation to GP practices, and can cause significant anxiety
NICE guidance does not recommend routine antibiotic treatment to patients who've suffered a tick bite
48
What is the management of Lymes disease?
Management of suspected/confirmed Lyme disease
## Footnote
doxycycline if early disease. Amoxicillin is an alternative if doxycycline is contraindicated (e.g. pregnancy)
ceftriaxone if disseminated disease
Jarisch-Herxheimer reaction is sometimes seen after initiating therapy: fever, rash, tachycardia after first dose of antibiotic (more commonly seen in syphilis, another spirochaetal disease)
49
What type of virus is Rabies?
RNA rhabdovirus (specifically a lyssavirus)
50
What are the features of Rabies?
prodrome: headache, fever, agitation
hydrophobia: water-provoking muscle spasms
hypersalivation
Negri bodies: cytoplasmic inclusion bodies found in infected neurons
51
What is the treatment for Rabies?
There is now considered to be 'no risk' of developing rabies following an animal bite in the UK and the majority of developed countries. Following an animal bite in at-risk countries:
## Footnote
the wound should be washed
if an individual is already immunised then 2 further doses of vaccine should be given
if not previously immunised then human rabies immunoglobulin (HRIG) should be given along with a full course of vaccination. If possible, the dose should be administered locally around the wound
52
What is the diagnostic test for rabies?
PCR to check for lyssavirus in the CSF
53
What is rat fever?
Leptospirosis
54
What are the clinical features of Influenza
2-4 days incubation period (1-7)
temperature up to 41° (38-40) for 3 days (1-5), 2 of the following:
cough (sore throat, rhinorrhoea),
myalgia,
headache,
malaise.
Predominance of systemic symptoms. Less common symptoms include tiredness, chills, headache, sore throat, runny nose, sneezing, nausea, vomiting, diarrhoea, loss of appetite, aching muscles, limb or joint pain
55
What is the treatment for influenza?
influenza A or B, both for treatment or prophylaxis, start within 48 hours of onset of symptoms/contact: oseltamivir, zanamivir
56
What are the complications of influenza?
common:
RESP: acute bronchitis, secondary bacterial pneumonia
less common:
RESP: primary viral pneumonia,
CV: myocarditis/pericarditis,
CNS: transverse myelitis/ Guillain Barre, myositis & myoglobinuria
57
What is tha pathogen associated with bronchiolitis?
RSV (respiratory syncytial virus) (75-80% of cases)
Mycoplasma and adenoviruses are also causes
58
Who often gets bronchioloitis?
Babies less than 1 years old = peak incidence is 3-6months
Maternal IgG protects gainst RSV
More common in winter
59
When is bronchiolitis more serious?
When there is bronchopulmonary dysplasia in premature babies
CF
Congenital heart disease
60
What are the features of bronchiolitis?
coryzal symptoms (including mild fever) precede:
dry cough
increasing breathlessness
wheezing, fine inspiratory crackles (not always present)
feeding difficulties associated with increasing dyspnoea are often the reason for hospital admission
61
When do NICE recommend immediate referral whenm there is a case of bronchiolitis?
apnoea (observed or reported)
child looks seriously unwell to a healthcare professional
severe respiratory distress, for example grunting, marked chest recession, or a respiratory rate of over 70 breaths/minute
central cyanosis
persistent oxygen saturation of less than 92% when breathing air.
62
When should clinicians refer to th hospital if there is a case of bronchiolitis according to NICE?
a respiratory rate of over 60 breaths/minute
difficulty with breastfeeding or inadequate oral fluid intake (50-75% of usual volume 'taking account of risk factors and using clinical judgement')
clinical dehydration.
63
What are the investigations for bronchiolitis?
immunofluorescence of nasopharyngeal secretions may show RSV
CXR: may show hyperinflation/patchy infiltrative change
64
What is management for bronchiolitis?
Largely supportive
humidified oxygen is given via a head box and is typically recommended if the oxygen saturations are persistently \< 92%
nasogastric feeding may be need if children cannot take enough fluid/feed by mouth
suction is sometimes used for excessive upper airway secretions
CPAP/ ventilation if severe
Ipratropium inhalers may help
Palivizumab (monoclonal Ab) given monthly as primary prophylaxis during RSV season to at-risk infants (ie: chronic lung disease, congenital heart disease)
65
What are the complications of bronchiolitis?
chronic wheeze, bronchiolitis obliterans (adenovirus)
66
What organism causes amoebic dysentry?
Entamobea Histolytica
67
What organism is most likely to cause invasive pulmonary aspergillosis?
A. fumigatus
68
What are the risk factors for invasive aspergillosis?
Neutropenia
Solid organ or allogenic stem cell ttransplant
Corticosteroids
Leukaemia and other haemotological malignancies
Cytotoxic chemotherapy
Advanced HIV disease
Severe COPD
Critically ill patients on intensive care units
Chronic granulomatous disease
69
What are the findings on CT that would indicate invasive pulmonary aspergillosis?
Dense, well circumscribed lesions with or without a halo sign
Air crescent sign
Cavity
70
When is an immunocompromised patient heavily suspected of having invasive pulmonary aspergillosis?
If they develop fever, new resp symptoms, (particularly pleural pain or haemoptysis) or a pleural rub.
71
What are the features of tracheobronchial aspergillosis?
Involvement is characterised by the formation of fungal plaques and ulceration
72
What are mycological ways to diagnose aspergillosis?
Using sputum, BAL fluid or bronchial brush to find one of the following:
Fungal elements indicating mould of aspergillus
Culturing a mould of aspergillosus
73
What blood test can be done to look for invasive pulmonary aspergillosis?
Detection of aspergillus cell wall components (galactomannan and B-1,2-glucan) in blood or BAL fluid and aspergillus DNA by PCR.)
74
What is treatment choice for invasive pulmonary aspergillosis?
Voriconazole
Second line agents include liposomal amphotericin, caspofungin or posaconazole.
75
What is sub-acute or chronic pulmonary aspergillosis?
Non-invasive complication of chronic lung disease such as COPD, TB, opportunistic mycobacterial disease or fibrotic lung disease
76
What disease does chronic pulmonary aspergillosis closely mimic?
TB
77
What are the features of chronic pulmonary aspergillosis?
Cough (with or without haemoptysis), weight loss, anorexia and fatigue over months or years
Associated fever, night sweats and elevated inflammatory markers
78
What are radiological features of chronic or subacute pulmonary aspergillosis?
Thick walled - cavities (predominantly apical)
Pulmonary infiltrates
Pleural thickening and later fibrosis
79
What are the three different dsecriptive names of chronic pulmonary aspergillosis?
CNPA (chronic necrotising)
Cavitatory
Fibrosing
80
What are the features of malaria?
fever
rigors
aching bones
adbo pain
headache
dysuria
frequency
sore throat
cough
fatigue
myalgia
nausea
vomiting
Signs:
none, splenomegaly, hepatomegaly, mild jaundice, anaemia, tachycardia
81
What are the investigations for malaria?
thick and thin blood films (Giemsa, Field’s stain)
schizonts on a blood film
quantitative buffy coat (QBC) - this is a fluorescence microscopy based malaria diagnostice test
rapid antigen tests (OptiMal and parasight F)
FBC (anaemia), raised ESR, raised CRP, U&E, LFT
82
What are the organisms that cause malaria?
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Plasmodium falciparum causes nearly all episodes of severe malaria. The other three types, of which Plasmodium vivax is the most common, cause 'benign' malaria
83
What are protective factors for malaria?
G6PD deficiency
HLA-B53
absence of Duffy antigens
Sickle cell anaemia
84
What are the features of severe malaria?
schizonts on a blood film
parasitaemia \> 2%
hypoglycaemia
acidosis
temperature \> 39 °C
severe anaemia
complications as below
85
What are the complications of malaria?
Complications
* cerebral malaria: seizures, coma
* acute renal failure: blackwater fever, secondary to intravascular haemolysis, mechanism unknown
* acute respiratory distress syndrome (ARDS)
* hypoglycaemia
* disseminated intravascular coagulation (DIC)
86
What might make you more likely to suffer from malaria?
Pregnancy
Previous splenectomy
87
What is the result of parasitisation of the maternal side of the placenta?
IUGR
Abortion
88
What are preventative measures for malaria?
awareness of risk per geographical area,
bite prevention (cover up at dawn and dusk, insect repellent sprays, lotions, mosquito coils, permethrin-impregnated mosquito nets)
chemoprophylaxis (malarone daily, doxycyline daily, mefloquine weekly, chloriquine weekly + proquanil daily
diagnosis & treatment)
89
What is the management of malaria?
Artemisinin treatment is recommended
Co-artemether (CoArtem or Riamet) contains artemether and lumefantrine - this is given as 4 pills, 6 times over 60 hours
OR
Quinine for 7 days plus doxycycline/clindamycin 7 days
OR
Malarone for 3 days
90
What is the treatment for severe or complicated malaria?
Severe malaria should be considered in any on-immune patient with aparasite count greater than 2% - medical emergency
Antimalarial chemotherapy
Correction of fluid, electrolytes, acid base balance
IV artesunate
IV quinine + oral doxycyline (or clindamycine)
switch to oral treatments when patient is stable and can swallow
91
What is a side effect of quinine?
Dysrhythmias
92
What are the treatments for other forms of malaria?
treatment of other species of malaria
chloroquine
riamet
add primaquine to eradicate liver hypnozoites this is in P vivax and P ovale (check for G6PD def - haemolysis may develop)
93
