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RACP Written Exam 2021 > Infectious Diseases > Flashcards

Infectious Diseases Flashcards

(129 cards)

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1
Q

Treatment for TB

A 
Two Months 
Rifampicin (Inducer of CYP/Yellow secretions) 
Isoniazid
Pyrazinamide
Ethambutol

Six Months
Rifampicin
Isoniazid

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2
Q

Duration of treatment for meningeal TB

A

12 months

Streptomycin replaces Ethambutol

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3
Q

Isonazid adverse effects

A

Peripheral neuropathy
Hepatitis
Rash

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4
Q

Rifampicin adverse effects

A

Febrile reactions
Hepatitis
Rash
GIT disturbance

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5
Q

Pyrazinamide adverse effects

A

Hepatitis
GIT disturbance
Hyperuricaemia

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6
Q

Streptomycin adverse effects

A

8th cranial nerve damage

Rash

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7
Q

Ethambutol adverse effects

A 
Retrobulbar neuritis (may present as colour vision loss) 
Arthralgia
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8
Q

TB Diagnosis

A

Two sputum samples (one early morning) for acid fast bacilli
Sputum culture = highest specificity

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9
Q

Chemoprophylaxis regimen for TB

A

Rifampicin + Isoniazid for 3 months
Isoniazid for 6 months

Offered to those who are positive for latent TB (TST/IGRA) or patients who are HIV infected and close contact with a smear positive individual.

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10
Q

Testing for latent TB

A

1) Turberculin skin test
- False +: BCG or infection with non-mycobacterium TB
- False -: immunosuppressed or overwhelming TB infection
2) IGRA

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11
Q

Testing for Syphilis

A

Non-Treponemal Tests: VDRL/RPR
(False positives from active infection with infectious mono, chickenpox and malaria as well as pregnancy)
(False negatives in secondary syphilis)
Treponemal Tests: Treponemal test remain positive even after treatment

Nb If Non-treponemal test + but treponema test - usually indicates a false positive finding.
If test positive in asymptomatic individual then needs to be repeated.

NB: Check treatment response at 3, 6 and 12 months with a nontreponemal test. Syphilis is considered cured if the nontreponemal titre falls by at least four-fold (two dilutions).

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12
Q

Brucellosis (Brucella) findings on culture and gram stain

A

Gram-negative coccobacilli
Nonencapsulated, nonmotile
Facultatively intracellular

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13
Q

Mechanism of action of neurominidase inhibitors

A

Neuraminidase inhibitors reduce viral shedding by interrupting the cleaving process of Neuraminidase.

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14
Q

Mechanism of action fo echinocandins

  • Anidulafungin
  • Caspofungin
  • Micafungin
A

Inhibit 1,3-beta-D-glucan synthase

Effect

  • Fungicidal against Candida
  • Fungistatic against Aspergillus
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15
Q

Mechanism of action of azoles

A

Impair the synthesis of ergosterol

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16
Q

Adverse effects of azoles

A

General: rash, headache, dizziness, nausea, vomiting, abdominal pain, diarrhoea, elevated liver enzymes

Specific: Thrombocytopenia and blue-green visual aura with voriconazole

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17
Q

Mechanism of action of Flucytosine

A

Converted to fluorouracil inhibits fungal DNA synthesis and is also incorporated into fungal RNA, affecting protein synthesis.

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18
Q

Adverse effects of flucytosine

A

Blood dyscrasias
Diarrhoea, nausea, vomiting, elevated liver enzymes (dose-related), rash

Nb: oxicity is associated with prolonged concentrations >100 mg/L. Need to undertake TDM

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19
Q

Amphotericin B mechanism of action

A

Binds irreversibly to ergosterol in fungal cell membranes causing cell death by altering their permeability and allowing leakage of intracellular components.

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20
Q

Amphotericin B adverse effects

A

nephrotoxicity
LFT derranagements: increased serum bilirubin, increased ALP,
Metabolic changes: hyperglycaemia, hyponatraemia
Other: tachycardia,

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21
Q

Linezolid mechanism of action

A

Inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit
Used for treatment of gram + and some anaerobes

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22
Q

Adverse effects of Linezolid

A 
Reversible myelosupression 
Serotonin syndrome (weak MAOI) 
Optic and peripheral neuropathy (interference with mitochondria activity) 
Lactic Acidosis (interference with mitochondria activity)
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23
Q

Mechanism of action of Guanine Analogue anti-virals

  • Aciclovir
  • Famciclovir
  • Ganciclovir
  • Valaciclovir
  • Valganciclovir
A

Guanine analogues
phosphorylated by virally-encoded cellular enzymes –> acyclovir triphosphate, which competitively inhibits viral DNA polymerase

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24
Q

Treatment of Syphilis

A

Penicillin

If allergic and non-pregnant doxycycline

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25
Mechanism of action of Tetracyclines | - Doxycycline
Bacteriostatic; inhibit bacterial protein synthesis by reversibly binding to 30S subunit of the ribosome
26
Adverse effects of tetracyclines
Photosensitivity Photo-onycholysis and nail discolouration Teratogenic post 18 weeks gestation (inhibit bone growth)
27
Glycopeptides mechanism of action - Vancomycin - Teicoplanin
Bactericidal; inhibit bacterial cell wall synthesis by preventing formation of peptidoglycan polymers.
28
Mechanisms of resistance of enterococcus species to vancomycin
Alteration of the peptidoglycan synthesis pathway
29
Daptomycin Mechanism of Action
Gram-positive bacterial cytoplasmic membranes in the presence of calcium, causing depolarisation, potassium efflux (impairing potassium-dependent DNA, RNA and protein synthesis) and cell death. Treatment of systemic and life-threatening infections caused by Gram-positive organisms
30
Interaction between HIV and CD4 cells
Attachment occurs by interaction of GP120 on the surface of the virus and the CD4 antigen receptor on the surface of the host cell Binding then occurs via a co-receptor - CCR5 on Macrophages - CXCR4 on CD4 cells
31
Red man syndrome
Occur from infusion of glycopeptide (note vancomycin > teicoplanin) Related to rate of infusion Note an allergic reaction although histamine release involved Treat with antihistamine (promethazine)
32
Mechanism of action of carbapenems - Meropenem - Etrapenem - Imipenem
Inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins. Usually bactericidal Febrile neutropenia Gram negative or Gram positive Anaerobes
33
Treatment for New Delhi metallo-beta-lactamase 1 (NDM-1)
Colistin or tigecycline
34
Colisitin mechanism of action
Bactericidal; interacts with lipopolysaccharides in the outer bacterial membrane changing its permeability.
35
Tigecycline mechanism of action
Binds to 30S ribosomal subunit preventing incorporation of amino acids into bacterial peptides; bacteriostatic.
36
Treatment regimen in HIV
2NRTI + NNRTI/PI/Integrase Inhibitor
37
When using a protease inhibitor why is ritonvair also used in the treatment of HIV
Ritonavir (a protease inhibitor in itself) interacts with both P-glycoprotein (reducing efflux) and inhibitors CYP3A leading to increased concentration and elimination half lives of other PIs.
38
Which form of malaria can result in the severest haemolysis
P Falciparum (invades red cells of all ages)
39
Criteria for severe P Falciparum malaria infection
Parasite count > 2% | Complication of malaria
40
Treatment for severe Falciparum malaria
IV Artesunate or IV Quinine If >10% circulating erythrocytes consider exchange transfusion
41
Empiric treatment for suspected bacterial meningitis
1) 3rd generation cephalosporin - Ceftriaxone/Cefotaxime 2) Dexamethasone 3) Ben pen - if alcoholic, older than 50, immunocompromised, pregnant or debilitated (to cover for Listeria) 4) Vancomycin - if concern for Strep pneumoniae (Gram-positive diplococci)
42
Main risk factors for HIV associated lipoatrophy/dystrophy
Stavudine but also zidovudine (NRTIs) Older age Low baseline triceps skin fold values
43
Prevention of hepatitis B when contaminated by source +HBV
Not vaccinated: Immunoglobulin + Hepatitis B vaccine Non responder to vaccine: Check source HBsAg is positive or if it cannot be obtained, the HCP should receive two doses of hepatitis B immunoglobulin (HBIG). The second dose of HBIG should be given one month after the first dose.
44
Amoebic Liver Abscess Treatment
``` Metronidazole 8-hourly for 7 days or Tinidazole 2 g orally, daily for 5 days and Paromycin 500 mg orally, 8-hourly for 7 day to eradicate cysts in the gut and prevent recurrence ```
45
Use of bactrim prophylaxis
PJP | Toxoplasmosis
46
HIV prophylaxis for patients with CD4 count <200 <50
<200: PJP prophylaxis with Bactrim (if allergic give damson. atovaquone or aerosolised pentamidine) <50: MAC prophylaxis with Azithromycin (unless on ART)
47
Cause of bullous impetigo
Staphylococcus aureus
48
Antibiotics for Streptococcal or Enterococcal Infective Endocarditis
Gentamicin and Benzylpenicillin
49
Antibiotics for Staphyloccocal Endocarditis
MSSA: Flucloxacillin 2g 4 hourly for 4-6 weeks MRSA: Vancomycin for 6weeks
50
Antibiotics for HACEK endocarditis with Beta Lactamase
Ceftriaxone 2g daily for 4-6 weeks
51
Important parameter for effectiveness of beta lactam antibiotics
Time over minimum inhibitory concentration (time dependent)
52
Important parameter for effectiveness of amino glycoside antibiotics
Concentration max/MIC (concentration dependent)
53
Important parameter for effectiveness of vancomycin
AUC/MIC is most important.
54
Treatment for severe tropical pneumonia (north of Tenant Creek) in patients considered at risk (diabetes, hazardous alcohol consumption, CKD, COPD or Immunosuppressive therapy) or Gram Negative Bacilli identified on culture
Meropenem + IV azithromycin
55
How does HIV gain entry to the CD4 cell?
Glycoprotein 120 and 41 attach to CD4 molecules changing their shape and the attaches to CCR5 or CXCR4 Virus is then allowed to enter the cell
56
Abacovir delayed hypersensitivity
HLAB*57.01
57
Window period in which HIV cannot be identified by ELISA antigen antibody testing
2-3 weeks (15 days)
58
Tenofovir mechanism of action
Reverse Transcriptase Inhibitor
59
Preferred treatment regimens for HIV
Integrase Inhibitor | 2 Nucelotide reverse transcriptase inhibitors
60
Mechanism of action of Nucleoside Reverse Transcriptase Inhibitors
Bind to viral reverse transcriptase at deoxynucleotide binding site and block DNA synthesis
61
Mechanism of non-nucleoside RTIs
Bind viral reverse transcriptase but not at deoxynucleotide binding site and alter the confirmation of enzyme blocking DNA synthesis
62
Protease Inhibitor mechanism of action
Block viral protease preventing maturation of the virus during and after budding Ritonavir/Lopinavir/Atazanavir/Darunavir
63
Use of ritonavir for HIV
Inhibits CYP3A4 which boosts other protease inhibitors
64
Integrase inhibitors
Block viral integrate preventing integration of viral DNA into host DNA Rategravir Elvitegravir Dolutegravir Bictregravir
65
When to commence PEP for HIV
Within 72hrs (best within 24hr)
66
Who to give post-exposure prophylaxis
Non-occupational: If HIV load is unknown or detectable - 3 drug regimen Occupational: - HIV load unknown or detectable: 3 drug regimen - HIV load known to be undetectable: 2 drug regimen
67
Prep regimen
Tenofovir + Emtricitabine
68
PEP regimen
- 2 Drug regimen: 28 days of Tenofovir + Emtricitabine or Lamivudine - 3 Drug regimen: 28 days Dolutegravir/Raltegravir/Rilpivirine
69
Monitoring while on Prep
6monthly: eGFR and ACR 12monthly: Hepatitis C
70
CD4 count and opportunistic infections
<250: PJP <150: Cryptococcal/Toxoplasma <50: MAC/Cytomegalovirus
71
Clinical presentation of PJP
Fever Non productive cough Marked exertion dyspnoea (well when sitting but drop sats on walking) CXR: Diffuse bilateral infiltrates (Basal and apical sparing) CT: Widespread ground glass changes
72
Diagnosis of PJP
CXR: Bilateral infiltrates with basal and apical sparing CT: Ground glass PCR of sputum BAL (>90% diagnostic yield)
73
Treatment of PJP
Cotrimoxazole 15-20mg/kg/day Allergy: IV Pentamidine, Dapsone or Atovaquone, Clindamycin + Primaquine If hypoxic consider adding steroids
74
Prophylaxis for PJP
CD <200 Cotrimoxazole daily or thrice weekly Pentamadine three weekly nebulised
75
Cryptococcal Infection in HIV
``` Commonly meningitis (sub acute headache and fever) Pulmonary Cryptococcus ```
76
Cryptococcal infection in HIV diagnosis
LP: Raised opening pressure, Low glucose and raised WCC and protein India ink and CRAG positive
77
Treatment of cryptococcal meningitis in HIV
LP/VP shunt Amphotericin and flucytosine for 1-2 weeks followed by 8 weeks of high dose fluconazole Ensure secondary prophylaxis until the CD 4 count rises
78
Treatment for IRIS
Steroids
79
Primary Prophylaxis in HIV (ETG)
CD4 <200: PJP --> Cotrimoxazole (Bactrim) either once daily or thrice weekly options CD4 <100: Toxoplasma --> Cotrimoxazole (Bactrim) either daily or thrice weekly CD4 <50: MAC --> Azithromycin 1.2gram once weekly or Clarithromycin 500mg BD
80
Live Vaccines contraindications
Should not be given to patients on anti-TNF or Rituximab | Need to give 4 weeks prior to commencement of same
81
Flu vaccine in immunosuppressed host
Twice in the first season and then twice thereafter | Caution with giving when patient on checkpoint inhibitor due to cytokine storm thereafter
82
Screening prior to Anti-TNF/DMARDS
Interferon Gamma assay
83
Treatment for latent TB infection on a patient pre anti-TNF or DMARD
9 month of isoniazid
84
Treatment/prophylaxis for patients pre commencement of rituximab with evidence of previous Hep B infection
HbSag+/- with Anti-Hbcore positive: Prophylaxis with Entecavir/tenofovir for 12 months after cessation go B cell depletion
85
When to commence PJP prophylaxis with cotrimoxazole?
- High dose corticosteroids >16-25mg/day or >4mg dexamethasone for >4weeks - TNF alpha inhibition - HIV with CD4<200 - Chemotherapy or monoclonal antibodies which cause prolonged lymphopenia
86
The ESCAPPM organisms
``` E: Enterobacter S: Serratia C: Citrobacter A: Acinetobacter P: Pseudomonas P: Porteus Valgaris M: Morganella Morganii ```
87
Mechanism of ESCAPPM antibiotic resistance
Inducible beta-lactamases (AmpC-cephalosporinases) which lead to resistance to third generation cephalosporins I.e When you give someone with enterobacter ceftriaxone it will induce the beta lactamase and then become resistant
88
Mechanism of ESBL antibiotic resistance
Plasmid mediated inactivation of all cephalosporins
89
Treatment for ESBL infections
Meropenem or Cotrimoxazole
90
Mechanism of Vancomycin action
Binds to peptidoglycan terminus D-ala-D-ala in cell walls sequestering the substrate from transpeptidase and inhibiting cell wall cross linking
91
Mechanism of Vancomycin Resistant Enterobaciae
D-ala-D-ala is changed to D-ala-D-lac si tgar vancomycin cannot bind.
92
Treatment for VRE
Ampicillin (If sensitive) Daptomycin Linezolid
93
Mechanism of Beta-Lactams
Bind to PBP and inhibit cell wall synthesis/repair | Bacteriocidal
94
Aminoglycosides mechanism of action
Inhibit protein synthesis by binding to the 30S ribosomal subunit Gentamicin, Tobramycin, Amikacin
95
Macrolides mechanism of action
Inhibit protein synthesis by preventing peptidyltransferase from adding the growing peptide attached to tRNA to the next amino acid Erythromycin, clarithromycin, roxithromycin, azithromycin
96
Tetracycline mechanism of action
Inhibit protein synthesis by binding to the 30s ribosomal subunit Doxyxycline, minocycline, tigecycline and tetracycline
97
Trimethoprim mechanism of action
Binds to dihydrofolate reductase and inhibits the reduction of dihydrofolic acid to tetrahydropholic acid
98
Sulfamethoxazole mechanism of action
Inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA)
99
Fluoroquinolones mechanism of action
Interfere with DNA synthesis by inhibiting topoisomerase thereby preventing bacterial DNA from unwinding and duplicating.
100
Rifamycin mechanism of action
Inhibit bacterial DNA-dependent RNA polymerase
101
Nitromidazole mechanism of action
Reduction of the nitro group on the antibiotic by nitroreductases produced by susceptible bacteria. (Metronidazole/Tinidazole)
102
Lincosamide mechanism of action
Bind to the 50S subunit of bacterial ribosomes Clindamycin
103
Mechanism of action of Linezolid
Binds to 50s subunit prevention of the formation of 70s subunit
104
Daptomycin mechanism of action
Binds to bacterial membranes and causes a rapid depolarisation which leads to cell death
105
Side effect of Daptomycin
Elevated CK and myalgias
106
Control of TB replication is dependent on which factors?
TNF alpha Interferon Gamma T cells
107
What affects the specitity to Mantoux
previous BCG | exposure to other non-TB mycobacteria
108
Advantage of interferon gamma release assay over Mantoux test
No cross reactivity with BCG or other Non-TB Mycobacterium
109
What does IGRA test
Previous exposure to TB
110
Gold standard for TB diagnosis
Culture
111
TB Meningitis CSF findings
High WCC (lymphocytic) Elevated protein Low glucose
112
Can IGRA determine between antibodies and latent infection?
No - therefore need to treat as if they are latent if IGRA positive
113
Risk factors for progression to active TB
- HIV (therefore test all patient with TB for HIV) - Transplant - Silicosis - Chronic renal failure - Biologic therapy (esp TNF alpha antagonist) - Prednisone <15mg/day - Diabetes
114
Treatment for latent TB
``` - 9 months Isoniazid or - 4 months Rifampicin or - 3 month Rifampicin and Isoniazid ```
115
Side effects of Isoniazid
Hepatotoxicity in 2% (increase with age)
116
Standard short course TB treatment
2 months RIPE --> 4 months RI
117
Adverse reactions from TB drugs
R: drug interactions, hepatitis, hypersensitivity I: Hepatisis, peripheral neuropathy (give with pyridoxine) E: Optic neuropathy P: Hepatitis, skin, polyarthralgia and gout Nb Hepatitis P>I>R
118
Hepatitis in TB
>2 ULN/Assymptomatic: Monitor >5 ULN or >3ULN with symptoms - stop If unable to stop TB treatment adopt in amikacin, moxifloaxcin
119
Most significant TB monoresistance
Isoniazid. Treatment for Isoniazid resistant TB: 6 months RPE+Levofloxacin
120
What is MDR-TB
TB resistant to Isoniazid and Rifampicin
121
Treatment for MDR TB
10% can have short course treatment ``` Levo/Moxi Bedaquiline Linezolid + Clofazimine/Cycloserine ```
122
New treatment for TV
Bedaquiline: Oral diarylquinoloe Delamanid: Nitromidazole, inhibits mycolic acid synthesis
123
HIV and TB dependent on CD4 count
CD4>200: Typical reactivation of TB | CD4<200: Atypical manifestations including diffuse lung infection (cavitation uncommon) and extra pulmonary TB
123
HIV and TB dependent on CD4 count
CD4>200: Typical reactivation of TB | CD4<200: Atypical manifestations including diffuse lung infection (cavitation uncommon) and extra pulmonary TB
124
Early ART treatment for patients with TB outcome
Improves mortality If CD4 0-50: Early ART (within two weeks) CD4>50: ART 8 weeks after starting TB treatment
125
HIV, TB and IRIS
10-40% of patient with TB/HIV starting ART experience IRIS Can consider prophylactic prednisone in those with CD4<100
126
Interaction between TB treatment and HIV
Rifampicin (TB) will increase the metabolism of protease inhibitors and therefore a high dose of a protease inhibitor may need to be used
127
Specific change to TB treatment for TB meningitis
Substitute moxifloxacin for ethambutol due to high CSF penetration Give dexamethasone at commencement of treatment Treat for 9-12 months
128
TB and Biologics
Higher rates of disseminated disease Can have rebound disease when biologic removed Adalimumab>Infliximab>Etanercept

RACP Written Exam 2021 (18 decks)

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