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Maintaining ICM knowledge > All things antimicrobial > Flashcards

All things antimicrobial Flashcards

1
Q

What are the species of candida that cause illness?

A

Candida:
- Albicans
- Tropicalis
- Parapsolosis
- Auris
- Glabrata
- Krusei

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2
Q

What species of aspergillosis are associated with illness?

A

Aspergillosis:
- Fumigatus
- Flavus
- Niger
- Terreus

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3
Q

What are the risk factors for invasive candidiasis?

A
  1. Immunosuppression: Neutropenia, organ transplants, cancer, haem malignancy, HIV etc
  2. Disruption to barriers: Indwelling catheters and prosthetic material, abdo surgery (bowel perf), acute pancreatitis, burns.
  3. Broad spectrum antibiotics
  4. Colonisation with candida spp.
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4
Q

What are the risk factors for invasive aspergillosis?

A
  1. Immunosuppression: Neutropenia, organ transplants, cancer, haem malignancy, high-dose steroids, HIV etc
  2. Mod-to-severe COPD
  3. Decompensated liver cirrhosis
  4. Viral pneumonia (covid / flu)
  5. Post ARDS
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5
Q

What are the clinical manifestations of invasive candidiasis?

A
  1. Catheter-associated bloodstream infection
  2. CNS
  3. Endophthalmitis
  4. Endocarditis
  5. Intra-abdominal infections
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6
Q

What are the clinical manifestations of invasive aspergillosis?

A
  1. Tracehobronchial aspergillosis (TBA)
  2. Rhinosinusitis and CNS infections
  3. Invasive pulmonary aspergillosis (IPA)
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7
Q

How is proven invasive candidiasis diagnosed?

A

Candida isolated from a sterile site e.g. peripheral blood culture (not from a line) or from sterile sampling of other tissue

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8
Q

How is probable invasive candidiasis diagnosed?

A
  1. Risk factors present
  2. Clinical or radiological features
  3. Non-diagnostic mycology evidence e.g. B-D glucan
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9
Q

What are the issues with using cultures to diagnose invasive candidiasis?

A

Slow to get a result and poor sensistivity

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10
Q

In non-neutropenic patients, when should empirical antifungals be started?

A

Should be considered if multiple risk factors in patients with a persistent fever of unknown source whilst on broad spectrum antibiotics

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11
Q

What is B-D glucan?

A

Detects fragments of fungal cell wall.
Low specificity but reasonable sensitivity.
Specificity is improved if 2 consecutive +ve results.
Helpful in the early cessation of empirical antifungals.

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12
Q

What is the firstline treatment of invasive candida in critically unwell patients?

A

Echocandins - they are all fungicidal and borad spectrum. Resistance is rae but has been reported in C.glabrata, parapsilosis and auris.

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13
Q

Where in the body do echinocandins not work effectively?

A

CNS
Eye
Urinary tract

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14
Q

What is the firstline treatment of invasive candidiasis in patients who are not critically ill?

A

Fluconazole - unless they’re likely to have a spp resistant to it.
Resistance is intrinsic in C.krusei and increasing in glabrata, tropicalis and auris.

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15
Q

How is invasive aspergillosis diagnosed?

A

Requires histopathological evidence combining +ve mycology plus tissue invasion.

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16
Q

How is a diagnosis of probable invasive aspergillosis made?

A
  1. Presence of risk factors
  2. IPA requires CT chest confirming pulmonary infiltrates or cavity lesions. TBA requires a bronch confirming tracheobronchial ulveration, nodule, pseudomenbrane, plaque or eschar.
  3. Mycology criteria:
    - aspergillosis +ve culture
    - +ve galactomannan from BAL (>1 optical density index)
    - +ve galactomannan >0.5 from serum
17
Q

What is first-line treatment for invasive aspergillosis?

A

Voriconazole / posaconazole or isuvaconazole.
Drug levels need monitoring.

18
Q

Where does staph aureus colonise?

A

Mucous membranes, skin and GIT.

19
Q

What factors increase the risk for nasal carriage of staph aureus?

A

Healthcare exposure, diabetes, dialysis, elicit drug use, HIV.

20
Q

What is the mortality a/w staph aureus bacteriaemia?

A

20-30%

21
Q

What is the likelihood of MRSA in North Europe vs USA?

A

< 5% Europe and ~ 50% USA.

22
Q

What key points need to be considered when managing a staph aureus bacteraemia?

A
  1. Appropriate abx
  2. ECHO
  3. Assessment for metastatic phenomena and source control
  4. Antibiotic duration
  5. ID consultation
23
Q

What type of bacteria is S.aureus?

A

Gram +ve facultatively anaerobic coccus. Which means that it will use O2 to make ATP when it’s available but that it can also ferment.

24
Q

What is Panton-Valentin Leukocidin?

A

A toxin produced by S.aureus. that’s associated with granulocyte destruction. It can be associated with deep-seated infections in hosts with relatively high infl markers but relative leukopenia.

25
Q

What timing of growth on BCs suggests S.aureus line infection?

A

If the time difference to +ve BC is 2+ hours between a central BC and a peripheral BC then this is suggestive of a central-line associated blood stream infection.

26
Q

What are the 3 main ways that vancomycin resistance to S.aureus can develop?

A
  1. Modifications to the bacteria cell wall
  2. MIC creep (not a true resistance)
  3. Acquisition of vanA plasmid - which alters the peptide target of glycopeptides
27
Q

Discuss appropriate abx therapy for S.aureus bacteriaemia

A
  • Empiric monotherapy with vanc is a/w worse outcomes that with an anti-staph beta-lactam
  • When sensitivities are unknown a anti-staph B-lactam and anti-MRSA agent should be used followed by appropriate de-escalation
  • Anti-staph B-lactam or cefazolin are preferred and clinically superior in MSSA bacteraemia
  • Taz is a/w increased mortality
  • Vanc or daptomycin for MRSA is the preferred option. Linezolid is a/w increased mortality.
28
Q

What is the role of ECHO in S.aureus bacteraemia?

A
  • It’s use is supported by the European society of cardiology guidelines
  • 18% at least who have IE don’t have peripheral stigmata
  • TOE has a higher sensitivity, both have similar specificity
  • TOE recommended in those with prosthetic heart valves or intra-cardiac devices
  • Those requiring a prolonged course of abx anyway don’t need a TOE assuming TTW has ruled out surgical indications of native IE
29
Q

How do you assess for metastatic S.aureus infection

A
  1. History - recent trauma, procedures, co-morbidities, foreign bodies, acute pain
  2. ?Lines - they’re the most common cause of hospital acquired S.aureus
  3. ?Skin / soft tissue infections - most common cause of community acquired.
  4. Exam - for soft tissue infection, IE stigmata, vertebral tenderness
  5. Investigations - including MRI of spine if vertebral tenderness, even if subtle. May need to be repeated. Radiologcal signs can lag behind clinical signs by 10 days. PET-CT may be useful.
30
Q

How long should antibiotics be continued in S.aureus bacteraemia?

A

Uncomplicated - minimum 2 weeks from 1st negative BC
Complicated - minimum 4 weeks. Deep-seated minimum 6 weeks.

31
Q

What defines an uncomplicated S.aureus bacteramiea?

A
  1. S.aureus clearance within 48-72 hours following start of antibiotics.
  2. Removable foci of infection
  3. Absence of metastatic phenomona
  4. No endovascular foreign material
  5. No evidence of IE
32
Q

What are the indications for surgical management of IE?

A
  1. Left-sided endocarditis (strong)
  2. Endocarditis induced valve dysfunction resulting in heart failure (strong)
  3. Endocarditis induced heart block, annular or aortic abscess, or destructive penetrative lesions (strong)
  4. Persistent infection (persistent bacteremia or fever ≥ 5-7 days after initiation of anti-staphylococcal antibiotics) (strong)
  5. Relapsing prosthetic valve endocarditis despite an appropriate antimicrobial course (mod)
  6. Recurrent emboli and persistent vegetations despite appropriate antimicrobial therapy (mod)
  7. Vegetations >10 mm in size with clinical evidence of embolic phenomena despite appropriate antimicrobial therapy (weak)
  8. Right-sided endocarditis with symptomatic severe valve dysfunction AND evidence of persistent infection (weak)
33
Q

What PCT values did the ADAPT-Sepsis RCT use to discontinue antibiotics?

A

< 0.25 strongly suggested and a fall > 80% or PCT > 025 and < 0.5 was suggested stopping.

Maintaining ICM knowledge (7 decks)

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