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Year 4 > Medicine - Infectious diseases > Flashcards

Medicine - Infectious diseases Flashcards

1
Q

Define neutropenia

A

Low WCC and inability to fight off infections

<0.5 or <1 and falling

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2
Q

Define SIRS

A 
systemic inflammatory response syndrome
the bodys response to injury
Must have:
- RR >20
- HR >90
- WCC >12x10^9
- Fever
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3
Q

Define sepsis

A
  • life threatening organ dysfunction in response to infection

Use Q-SOFA:

  • BP <100 systolic
  • Altered GCS
  • RR >22
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4
Q

Define septic shock

A

Sepsis with a high lactate despite adequate fluid resuscitation

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5
Q

What are the SIRS criteria?

A

RR > 20
HR > 90
WCC >12
Fever

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6
Q

What are the Q-SOFA criteria?

A

BP <100 systolic
Altered GCS/confusion
RR >22

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7
Q

What are the three main steps in the pathogenesis of sepsis?

A

1) Immune system activation
2) Endothelial and coagulation system
3) Inflammation and organ dysfunction

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8
Q

What are the S/Sx and the RFx for sepsis?

A

RFx:

  • malignancy
  • immunosuppression
  • > 65yrs
  • alcohol
  • DM
  • haemodialysis

S/Sx:

  • Reduced UO
  • tachy HR/RR
  • low GCS
  • fever
  • reduced CRT
  • reduced O2 sats
  • cyanosis
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9
Q

Describe the treatment of sepsis

A

Sepsis 6! (BAFLOU)

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10
Q

Differentiate infection from intoxication

A

Infection = pathogenesis occurs in gut after ingestion e.g. E.coli, salmonella

Intoxication = pathogen/toxins grow on food before ingestion, shorter incubation period e.g. bacillus cereus

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11
Q

Define gastroenteritis and what are its common causes?

Name 4 organisms which can cause bloody diarrhoea

A

Gastroenteritis = diarrhoea +/- vomiting due to enteric infection with virus/bacteria/parasite

Campylobacter
E.coli
Salmonella
Shigella

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12
Q

What investigations should be carried out for someone with acute diarrhoea/gastroenteritis?

A 
Hx and Ex
Stool cultures
Bloods: FBC (WCC, Hb, plts), U&amp;E's (low K, high urea/cr), antibodies? (IBD)
AXR
Endoscopy
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13
Q

How should gastroenteritis be treated?

A

Most mild infections resolve spontaneously
Maintain hydration
No anti-motility agents
ONLY use Abx if severe and prolonged

Infection control and pt education/PH measures

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14
Q

Describe the cause, presentation, diagnosis and treatment of influenza

A

Virus
Types A/B - cause serious infection
Type C - causes no significant illness
Presents: sore throat, cough, in winter, unvaccinated?
Clinical diagnosis
Prophylactic vaccine/can give tamiflu if severe
Complications -> OM, sinusitis, pneumonia

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15
Q

Describe the cause, presentation, diagnosis and treatment of the common cold

A

Common in winter
Caused by virus: rhinovirus/coronovirus
Presents: sore throat, runny nose, cough, headache
Clinical diagnosis with no vaccine/treatment
Complications -> OM, sinusitis

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16
Q

Describe the cause, presentation, diagnosis and treatment of pharyngitis

A

Viral or bacterial causes (usually adenovirus)
Presents with:
- red swollen tonsils, red throat, sore head (viral)
- grey furry tongue, red throat, swollen uvula, whitish spots (bacterial)

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17
Q

Describe the cause, presentation, diagnosis and treatment of infectious mononucleosis

A

EBV infection which targets B lymphocytes and oropharyngeal epithelial cells
Presents:
- sore throat, fever, weight loss, lymphadenopathy, splenomegaly, jaundice, hepatomegaly
Clinical diagnosis

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18
Q

Describe the cause, presentation, diagnosis and treatment of croup

A

Due to viruses: influenze, parainfluenza, RSV, coronavirus
Upper airway inflammation and oedema, with distinctive barking cough and wheeze/stridor/sternal in-drawing
Clinical diagnosis
Tx with steroids and supportive care

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19
Q

Describe the cause, presentation, diagnosis and treatment of bronchiolitis

A

Commonly affects children <2 yrs, but also in elderly/immunocompromised adults
Infection of the bronchioles
Nosocomial (originates in hospital) -> usually RSV
Fts: cough, tachypnoea, rhinitis, fever
Clinical diagnosis
Treatment: prophylacis w/ palivizumab (a monoclonal antibody given to those at risk)

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20
Q

What are the main causative agents of cellulitis?

A

Common organisms:
Group A beta-haemolytic strep (s. pyogenes)
Staph aureus

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21
Q

What are the risk factors for the development of cellulitis?

A 
DM
PVD
Skin breaks
Oedema
Venous insufficiency
Eczema
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22
Q

What are the signs/symptoms of cellulitis?

A 
Erythema
Warm
Tender
Oedematous
Broken skin
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23
Q

What investigations should be carried out for someone with suspected cellulitis?

A 
Hx and Ex
FBC (WCC)
Blood cultures
Skin biopsy
?x-ray (osteomyelitis)
?USS (if abscess)
?MRI (if nec fasc)

Enron classification!

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24
Q

What antibiotics are used to treat cellulitis?

A

Fat is Clinically Gross

Fluclox
Clindamycin
Gent

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25
Q

What is MRSA and describe why it is so difficult to treat:

A

Methicillin resistant staph aureus
G+
Causes skin/soft tissue/joint/lung infections
Lives on moist body areas
Chronic carriers have increased infection risk
The bacteria has a MecA gene which encodes for a type of PBP which antibiotics cannot penetrate the wall of the bacteria through

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26
Q

What are the RFx for MRSA development?

A

Hospitals!
Abx exposure
Surgery
Nursing homes

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27
Q

How is MRSA treated?

A

If pt is tested positive, give pre-surgery peptidoglycan coverage: vanc/teicoplanin

Prevention is key: hand hygiene, antimicrobial stewardship

Treatment -> clind/vanc/teicoplanin/co-trimoxazole

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28
Q

What is C.Diff and the aetiology behind its infections?

A

Anaerobic G+ bacterial living in the gut
Forms spores = difficult to eradicate
Is the most common cause of Abx associated diarrhoea
Produces 2 toxins (A&B) (the testing of the toxins in the stool is essential as cultures can be + in healthy individuals)

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29
Q

What antibiotics can cause C.Diff?

A

Co-amoxiclav
Clindamycin
Ciprofloxacin
Cephalosporins

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30
Q

What are the components of the C.Diff severity score?

A 
(measurements if severe): CAT-WC
Creatinine - >1.5x baseline
Albumin - <25
Temperature - >38.5
WCC - >15
Colon dilatation - >6cm
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31
Q

How should C.Diff be investigated for its diagnosis?

A

Bloods: FBC, WCC, albumin, creatinine, CRP…
Stool cultures and toxin testing
AXR/erect CXR

32
Q

How should C.Diff be treated?

A 
SIGHT
Suspect it
Isolate
Gloves and apron (PPI)
Hand washing and soap
Test immediately
Stop any potential causative antibiotics
Supportive - bowel rest and fluids
Oral vanc/metronidazole
?faecal transplant
?surgical intervention
33
Q

What is the definition of meningitis and its main causes?

A

Inflammation of meninges +/- cerebrum
Caused by various bacteria
Can be primary or secondary (TB/malaria)

Main bacterial causes:

  • neisseria gonorrhoea (G- diplococi)
  • strep pneumoniae (G+ strep)

Viral causes:
- mumps, HSV, HIV

34
Q

What are the RFx and the S/Sx of meningitis?

A

RFx:

  • ear infections
  • throat infections
  • neurosurgery
  • alcohol
  • pregnancy
  • immunosuppression

S/Sx:

  • pyrexia
  • meningism (photophobia, neck stiffness, headache, Kernigs sign)
  • low GCS
  • petechial non-blanching rash
35
Q

What is a common differential for meningitis which can infect immunocompromised individuals

A

cryptococcal meningitis

caused by cryptococcus neoformans (fungal!)

36
Q

How is meningitis investigated (differentiate the LP findings!)

A 
Hx and Ex
Blood cultures and PCR
Full set of bloods
Throat gargle
LP! CSF cell count and culture

->

Glucose low if bacterial
WCC high but neutrophils (bacterial) or lymphocytes (viral)
Protein high in bacterial but N/high in viral
Cloudy if bacterial or clear if viral
Opening pressure high/normal if bacterial, or normal if viral

37
Q

How is meningitis managed?

A

Antibiotics immediately

  • > IV ceftriaxone (if bacterial) and amoxicillin
  • > +/- dexamethasone

Prophylactically give close contacts ciprofloxacin/rifampicin

38
Q

Describe HHV1 & 2

A

Viruses live in sensory neurons causing lifelong latent infection which can reactivate
Presents as:
- herpes labialis (lips) = HSV1
- genital herpes = HSV2

Tx: clinically/scraping PCR
Give aciclovir

39
Q

Describe HHV3

A

Varicella zoster virus
Presents as chicken pox/shingles
Transmitted through respiratory droplets
Chicken pox initially, then virus lives in neurons and when reactivated causes shingles in dermatomal distribution

Chicken pox are infective 1-2 days pre and 5 days post scabbing over
Tx: aciclovir
Prevention: vaccine for >70yr olds to prevent shingles reactivation
VSV immunoglobulin can be given to non-immune exposed and immunosuppressed individuals

40
Q

Describe HHV4

A

EBV! Can be lytic or latent infection
See other notes
Can cause benign (IM) and malignant (lymphoma) disease

41
Q

Describe HHV5

A

CMV (cytomegalovirus)
usually affects immunosuppressed individuals
can cause infection of the GI tract

42
Q

Describe some oncogenic viruses

A

EBV -> lymphoma
HPV -> head/neck/vaginal/cervical cancer
HepB/C -> liver cancer

43
Q

Describe TB and its risk factors for development:

A

Bacterial infection with mycobacterium tuberculosis
Can be dormant/active and pulmonary/extra-pulmonary
Latent = the infection without the disease, granulomas form to stop the bacteria being destroyed by immune system

44
Q

What are the signs/symptoms of TB?

A

Primary TB -> normally asymptomatic
Post-primary TB -> infection is reactivated and symptoms present: fever/night sweats
Can affect all organ systems:
lungs -> dry productive cough, haemoptysis
lymphadenopathy
systemic -> fever, malaise, weight loss, clubbing, erythema nodosum
GI -> colicky abdominal pain, vomiting, bowel obstruction
CNS -> brain/SC/meninges infection causing neurological defects
GU -> dysuria, loin pain, haematuria, fibrosis, infertility
cardiac -> pericarditis

45
Q

What are the investigations to diagnose active/latent TB?

A 
Latent TB: 
- mantoux skin testing
- IGRAS (interferon-Y-release assays) measure the release of If-Y from T cells reacting to the TB antigen
Active TB:
- blood cultures -> take 2/52 to grow and 48 days to confirm with Ziehl Nielson stain (MBT turn red)
- sputum testing
CXR
- NAAT test
46
Q

What is the treatment of TB?

A

RIPE!

  • rifampicin -> 2/12 int, 4/12 cont. Bacteriocidal. Turns urine red, induces cytochrome P450 system
  • isoniazide -> 2/12 int, 4/12 cont. Bacteriocidal. Give prophylactic pyridoxine to avoid peripheral neuropathy as it inhibits vitamin B6 formation
  • pyrazinamide -> 2/12 int. Bacteriocidal. Hepatotoxic
  • ethambutol -> 2/12 int. Bacteriostatic. Monitor visual acuity as it can cause colour blindness, reduced acuity and optic neuritis
47
Q

Define HIV and how it can be transmitted:

A

retrovirus
infects CD4+ T lymphocytes and replicates
progressive immune system dysfunction, opportunistic infection and malignancy can arise

Transmission can be:

  • horizontal -> blood, body fluid, sex, breast milk, needle stick
  • vertical -> mother to baby
48
Q

What is the pathogenesis of HIV and the enzymes involved?

A
  • HIV expresses glycoproteins GP41 and GP120 which bind to surface receptors on CD4 cells
  • virus then enters CD4 cells and releases 3 enzymes (R-TIP)
  • reverse transcriptase -> carries out RT of each RNA strand forming a double helix
  • integrase -> cleaves a nucleotide from the end of the viral DNA (makes it sticky), and carries it into the host nucleus to incorporate into the host DNA
  • protease -> cleaves large cytoplasmic proteins to make capsid
49
Q

What are the three phases of HIV infection and the signs/symptoms?

A
  • high risk groups: MSM, black africans IVDU
    3 phases:
  • primary HIV -> symptoms 2-4 weeks after initial infection
  • persistent generalised lymphadenopathy -> ~3 months
  • asymptomatic latent phase -> HIV virus continually replicates, eventually leading to AIDS
    KNOW GRAPH!
50
Q

What investigations should be carried out to diagnose HIV?

A

Bloods (low WCC?)
ELIZA = liquid IHC for the HIV Ab/Ag
NAAT/viral PCR -> used to measure viral load and response to treatment
CD4+ cell count -> monitor immune system
-> high = very infectious and symptomatic
-> low = uninfectious and treatment is working
-> <200 cells/ul = AIDS

51
Q

What are the treatments for HIV?

A

2 NRTI and 1 drug from another class
(F-NIP)
-fusion inhibitors (stop GP-receptor binding)
-non-nucleoside/nucleoside reverse transcriptase inhibitors (inhibit RT enzyme)
-integrase inhibitors (stop action of integrase so that HIV DNA cannot be incorporated into the genome)
-protease inhibitors (stops protein fragmentation so that new capsid cannot be formed)

PEP and PrEP

  • post-exposure prophylaxis (anti-retroviral medication taken <72hrs since possible exposure to prevent infection)
  • pre-exposure prophylaxis (pill taken daily to prevent people at high risk of HIV from contracting it)
52
Q

What complication of HIV can arise?

A

Acute seroconversion

53
Q

Describe gonorrohoea

A
  • caused by neisseria gonorrhoea
  • causes purulent vaginal/urethral discharge + dysuria
  • 50% asymptomatic
  • diagnose with NAAT using vaginal swab (F) or first pass urine (M)
  • treat with IM ceftriaxone and PO azithromycin
  • 1/3rd pts will also have chlamydia
54
Q

Describe chlamydia

A
  • caused by chlamydia tracheomatis
  • sometimes asymptomatic
  • in females: dysuria, vaginal discharge, bleeding (inter-menstrual/post-coital)
  • in males: discharge, dysuria
  • lungs: pneumonia
  • eyes: conjunctivitis
  • diagnose with NAAT (using vaginal discharge (F) or first pass urine (M))
  • treat with doxycycline
  • short and long term complications (see notes)
55
Q

Describe syphilis

A
  • caused by treponema pallidum
  • slow growing bacteria therefore long presentation
  • various phases of presentation:
  • > primary = 3/52 of painless non-itchy chancres on skin and genital regions
  • > secondary = 3/12 of hand/skin rash
  • > latent phase
  • > tertiary phase = cardiac/neuro/skin symptoms
  • diagnose with blood test and treat with penicillin injections
  • complication -> neurosyphilis
56
Q

Describe HPV

A
  • human papilloma virus
  • strains 6+11 = genital warts
  • strains 16 + 18 = cervical cancer
  • causes warts of throat/mouth/genitals
  • treat with topical therapy/cryotherapy
  • prophylactic vaccine available for males and females now
57
Q

Describe trichomoniasis

A
  • bacterial infection caused by trichomonas vaginalis
  • females: profuse vaginal pain and discharge
  • males: asymptomatic
  • diagnose with NAAT
  • treat with metronidazole
58
Q

Describe bacterial vaginosis

A
  • not a true STI but associated with STI’s
  • overgrowth of bacteria naturally found in the vagina
  • thin, white, fishy smelling discharge with no irritation/soreness
  • 50% cases asymptomatic
  • carry out gram-stain to explore vaginal flora
  • treat with:
  • > oral/PV metronidazole
  • > PV clindamycin
59
Q

Describe the aetiology and pathogenesis of malaria and the common causative agents

A

Plasmodium falciparum is the most common!
Other types of plasmodium also (vivax, ovale…)

A parasitic infection, with inoculation period of 1-2 weeks
Only female parasites bite
Sporazoites enter in saliva during bite, mature in liver, then move from hepatocytes into RBCs and cause clinical presentation

60
Q

How does malaria present and what are its differentials?

A

Non specific: Fever, headaches, malaise, sweats, cough, diarrhoea, myalgia

Other travellers diseases

61
Q

What investigations should you carry out if you suspect malaria?

A 
Microscopy -> thick and thin blood film (will show ringform trophozoites)
PCR antigen testing
Bloods -> FBC, LFT, U&amp;E, CRP
HIV test
Urine/stool microscopy and culture
Serology/OCR for Dengue fever
CXR
Liver USS
62
Q

How is malaria prevented and treated?

A

Prevention:
- malarone tablets
- vector control (avoid stagnant wanter, use air conditioning/nets/DEET)
Treatment = Quinine!

63
Q

Name some common infections in the immunocompromised host:

A
  • neutropenia
  • chronic granulomatous disease
  • pneumocystitis jerovecii
  • aspergillus
  • HSV
  • VSV
  • CMV
  • stem cell transplants = GvHD
64
Q

Name the 4 main causes of fever in the returning traveller

A
  • malaria
  • dengue fever
  • typhoid (caused by salmonella typhi/paratyphi)
  • haemorrhagic fever
65
Q

What is the predominant virus causing IM?

A

EBV

66
Q

What is the definition of pyrexia of unknown origin?

A
  • pyrexia for >3 weeks with no identified cause after 3 days in hospital/>3 outpatient visits
67
Q

What infection causes tetanus and describe it?

A

Caused by clostridium tetani spores (found in soil)
Enters through skin breaks and produces a neurotoxin called tetanosporin, causing muscle contraction/spasms
May present with trismus (jaw lock) or risus sardonicus (grin-like posture of hypertonic facial muscles)

68
Q

What infection causes cholera and describe it?

A

Caused by vibrio cholerae found in faecally contaminated water
Bacteria produce cholera toxin, causes massive volumes of diarrhoea
- 75% asymptomatic
- 25% = rice water profuse watery stool
- may cause metabolic acidosis and hyperkalaemia
- treatment = hydration

69
Q

What infection causes leprosy and describe it?

A

Caused by mycobacterium leprae
5-20 yrs incubation period
affects skin, nerves and mucous membranes: ulcers, weakness, epistaxis, sensory loss

70
Q

What infection causes rabies and describe it?

A

Caused by rhabdovirus -> transmitted through saliva/CNS tissue usually from an infected mammal
S/Sx: odd behaviour, paralysis, agitation, fever, malaise

71
Q

What infection causes roundworm and describe it?

A

a parasitic infection (ascariasis)
contamination of microscopic ascaris eggs in contaminated food/water
Usually asymptomatic but may notice worms in stool

72
Q

What infection causes tapeworm and describe it?

A

a parasitic infection caused by various types of worm (taenia solium, taenia saginata)

73
Q

What infection causes toxoplasmosis and describe it?

A

toxoplasma gondii parasite
Can be transmitted in animal faeces/raw meat
90% asymptomatic, 10% self-limiting cervical lymphadeopathy
- if immunosuppressed, disseminated disease can occur (all the -itises e.g. myocarditis, hepatitis, pneumonitis, encephalitis)

74
Q

What causes lyme disease and describe it

A

Tick-borne, caused by borrelia burgdofen
Many people do not remember being bitten, infection appears 48-72 after attachment
Present over days -> yrs progressing from pain, itch, fever, erythema on to dermatitis and lyme arthritis

75
Q

What causes measles and describe it

A

Highly contagious virus, now rare due to MMR vaccine
Transmitted through respiratory droplets
Common cause of encephalitis
2-4 day prodrome of fever, runny nose, diarrhoea, conjunctivitis -> then koplik spots (white spots on red buccal mucosa) present with a maculopapular rash

76
Q

What causes mumps and describe it

A

Highly contagious virus, now rare due to MMR vaccine
Transmitted through respiratory droplets and presents with prodrome of:
- fever
- myalgia
- headache
- painful swollen and tender salivary glands

Year 4 (28 decks)

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