Infectious Diseases Flashcards
(160 cards)
1
Q
Most common cause of bacterial cellulitis
A
Group A/C/G strep
2
Q
Cause of nec fas
A
Group A strep, toxin mediated Clostridium perfringens Polymicrobial - e.g. fourniers gangrene
3
Q
Role of clindamycin in necrotising fasciitis
A
stop protein synthesis and toxin production
4
Q
Cellulitis infection associated with cat bites
A
Pasteurella multocida - resistant to fluclox and cephazol; sensitive to amoxil and 3rd generation ceflosplorins. Need plastics involvement due to deep wound
5
Q
Cellulitis associated with fish/shellfish exposure
A
erysipelothrix - associated with endocarditis
6
Q
Clinical distinguishing feature of erysipelas
A
Sharp border
7
Q
incubation period for falciparum malaria
A
7-10 days (but can have delayed presentation; especially if there’s been prophylaxis)
8
Q
Immunochromographic test
A
Paired with a thick and thin for detection of malaria antigen (best for falciparum)
9
Q
Dengue incubation period
A
maximum 2 weeks
10
Q
What test do you do in conjunction with TB PCR in diagnosis
A
genexpert testing for rifampicin resistance - rifampicin resistance would suggest multi-drug resistance TB
11
Q
What diagnostic investigation for pleural TB
A
pleural biopsy
12
Q
Strongylodiasis infection - how to acquire
A
Usually from walking barefoot in tropical regions
13
Q
What happens to eosinophils in bacterial infections
A
Hypooesinophilia due to TH1 activation
14
Q
What is streptococcus milleri associated with
A
Abscess formation
15
Q
Treatment for giardia
A
Tinidazole (then metronidazole)
16
Q
What kind of bacterial is salmonella typhi
A
gram negative bacillus
17
Q
What is the rash pattern in measles and 5 ‘c’s
A
starts at neck and ears and spreads down the trunk cough coryzal koplik conjunctivitis crappy
18
Q
NS1 antigen
A
part of the dengue virus
19
Q
Dengue shock syndrome - suggestive feature on FBE
A
rise in haematocrit due to leaking capillaries
20
Q
Most common cause of liver abscess in SE Asia
A
Klebsiella pneumoniae (hypervirulence strain in asia)
21
Q
Melioidosis
A
Burkholderia pseudomallei (Northen Australia)
22
Q
What do you need to do before giving tafenoquine
A
G6PD testing (for Malaria prophylaxis)
23
Q
How does beta lactamases cause resistance and what organisms are they most commonly found
A
Enzymatic degradation Gram -ve> gram +ve
24
Q
“non multi” MRSA vs “multi” MRSA
A
non multi is generally community acquired still sensitive to clindamycin, bactrim this is due to resistance genes being co-transmitted (e.g. through plasmids)
25
What gram negative rod has an intrinsic narrow spectrum beta-lactamases
Klebsiella (but wildtype should be susceptible to augmentin, ceftriaxone etc)
26
What gram negatives have chromosomal mediated (sometimes expressed) beta lactamases
ESCAPPM E: Enterobacter spp. S: Serratia spp. C: Citrobacter freundii. H: Hafnia spp. Cannot use 2rd gen cephalosporin for \>48hr. The beta lactamase is inducible. The enzyme is called AmpC
27
What gram negatives have an intrinsic resistance to carbapenems
Stenotrophomonas But not very pathogenic
28
what is a common mutation for quinolone resistance?
fluoroquinolone gyrA mutation
29
Long term bug lines
gram positive, sticky gram negatives (pseudomonas), candida
30
Where does tigecycline distribute to
It is poorly protein bound so serum levels are low but can distribute well into tissues. Not good for bacteraemia.
31
What empirical therapy should be used in suspected CPE
Meropenem 2g TDS PLUS aminoglycoside (amikacin) OR colistin PLUS fosfomycin IV or tigecycline
32
What class of drug is colistin
polymixin
33
What bug implicated in severe mucositis
VRE/enterococcus
34
What enterococcus species is more likely to be resistant
Entercoccus faecium The other common enterococcus is faecalis
35
Linezolid side effects
myelosuppression peripheral neuropathy optic issues
36
Should beta lactams have peak concentrations or more time above MIC?
More time above MIC. Aim for \>50% (but more is better). Beta lactams do better w more frequent dosing
37
Micro associated w ethmoid surgery
Pneumococcal
38
What antibotics can cause prolonged INR
erythromycin
39
What does bactrim do to the kidneys
inhibits tubular secretion of potassium and creatinine
40
What kind of HIV drug is ritonavir
Booster drug (often used w/ protease inhibitors)
41
What does ritonavir do to methadone
Decrease plasma methadone concentration
42
What is panton-valentine Leucocidin toxin most associated with
pyogenic skin infections community acquired MRSA
43
group D strep (strep gallolyticus/bovis) - what malignancy is it associated with
colon cancer
44
most common organism associated with IVDU IE
staph aureus
45
what heart disease does streptococcus pyogenes
rheumatic heart disease - M protein
46
What are HACEK organisms susceptible to
ceftriaxone
47
When is the best time to take blood cultures
before the febrile episode
48
What is the most common valvular lesion predisposing to infective endocarditis
mitral valve prolapse (but mitral stenosis in places w rheumatic fever)
49
what kind of valves should get antibiotic prophylaxis for dental procedures
prosthetic valves
50
what is the main risk factor for C. Diff infection
advancing age
51
c. diff binary toxin
very virulent c. diff toxin more likely to cause toxic megacolon
52
what causes a pandemic flu in influenzae A
Antigenic shift in H and N proteins of influenzae A
53
what is a neuraminidase
osteltamivir
54
wht is the greatest risk factor for severe respiratory disease asosicated with the 2009 H1N1 swine flu
BMI \>35 second biggest is pregnancy
55
what haematological condition is mycoplasma pneumonia associated with
cold agglutinin haemolysis
56
what is the most treatment option most likely to improve chronic fatigue
material explaining chronic fatigue supervised graded exercise program is next
57
prevention of rheumatic fever recurrence in young patients with rheumatic heart disease
secondary prophylaxis with benzathine penicillin G 3 weekly
58
the most common cause of viral meningitis
enterovirus
59
what is the most common cause of recurrent meningitis
HSV2
60
the most common cause of viral meningitis
enterovirus
61
what is the most common cause of recurrent meningitis
HSV2
62
What opportunistic infections are likely to occur in a HIV patient with CD4 200-500
Herpes zoster, pneumococcal pneumonia, oral candidiasis, tuberculosis
63
What and when should primary prophylaxis be initiated in HIV
CD4 \<200 PJP and CNS toxoplasmosis - cotrimoxazole
CD4 \<50 MAC - azithromycin
64
When to start ART in the symptomatic HIV patient or CD4 \<200 (OI, TB)
1. Investigate and commence treatment for OI
2. Commence ART 2-4 weeks later (or earlier)
3. TB and CD4 \>50 - do not start ART until 4-8 weeks of TB treatment
4. TB and CD \<50 - initiate ART at 2-4 weeks
5. If cryptococcal meningitis or other neurological OP - unclear evidence
65
Steps in HIV viral life cycle
66
Adverse effects of tenofovir
Renal fx; Osteopenia
67
MOA of tenofovir
nucleotide analogue
68
what is the renal function cut off in tenofovir
CrCl \<30 mL/min
69
What HIV medications are used as boosters?
Ritonavir (PI) and colbistat (CYP3A4 inhibitor)
70
What HIV ARTs cause dyslipidaemia?
Protease inhibitors
Atazanavir (ATZ)
Darunavir (DRV)
Lopinavir/ritonavir (LPV/rtv)
71
Recommended initial regimens for most people with HIV (2)
BIC/TAF/FTC - two NRTIs and an INSTI (Bictegravir, tenofivir, Emtricitabine)
DTG/ABC/3TC (if HLA-B\*5701 negative) - abacavir (ABC)/lamivudine (3TC)/dolutegravir
72
What HIV mediations are metabolised by CYP4503A4
Protease inhibitors (inhibits P450 3A4) and NNRTI (induces CYP P4504A4)
73
What is virologic failure in HIV?
Inability to maintain suppression of viral replication (to an HIV RNA level \<200 copies/mL)
74
When should testing for drug resistane be done in HIV patients
All at baseline and for all pregnant women
At virologic failure
75
what HIV ARTs leads to lipoatrophy
stavudine or zidovudine (Old NRTIs)
76
what HIV ARTs cause visceral fat accumulation and buffalo hump ?
Protease inhibitor use
77
PBS listed PrEP
Tenofovir + emtricitabine (TDF + FTC)
78
What respiratory OI is a HIV patient at risk of if CD4 \<50
MAC, CMV pneumonitis (and all the other stuff at higher CD4 counts)
79
Typical PJP CXR findings
diffuse bilateral, symmetrical interstitial infiltrates
CT - diffuse groundglass changes
80
Cryptococcis treatment
liposomal amphotericin B 3 mg/kg IV daily + flucytosine 25 mg/kg QID (flucytosine rarely tolerated, levels must be monitored) – 2-3 weeks
Need repeat LP to check clearance
81
What is the most common cause of death in AIDS patients worldwide
TB
82
Treatment of disseminated MAC
Clarithromycin + ethambutol
83
CMV in HIV most common clinical manifestation of CMV end organ disease
retinitis
84
Kaposi sarcoma viral aetiology
HHV 8
85
Which HIV strain is more predominent
HIV 1 by far
86
Differences between HIV 1 and 2
1. Distribution
2. Viral load
3. CD4+ counts in undetectable viral load
4. Coreceptor use
5. Ineffective HRT
87
What is the MOA of maraviroc?
inhibits CCR5 binding (entry)
88
What is the MOA of enfuviritide
HIV drug - inhibits fusion of the HIV onto the host cell
89
MOA of abacavir
NRTI
90
MOA of lamivudine
NRTI
91
MOA of emtricitabine
NRTI
92
MOA of zidovudine
NRTI
93
MOA of raltegravir
Integrase inhibitor
94
MOA dolutegravir
InSTIs
95
HIV entry co-receptors
CCR5 co-receptor; CXCR4 co-receptor]
CCR5 is present on many types of cells
96
What is immune activation associated with in HIV
Increased mortality and morbidity
Increased atherosclerosis
Poor CD4 recovery
97
What mutation is assocaited with HIV protection
Delta32 mutation in CCR5
98
What is control of MTB dependent on?
T-cell immunity, IFNgamma, TNFalpha
99
What is the second most common manifestation of active TB?
Tuberculosis lymphadenitiis
100
Treatment of TB meningitis
isoniazid (H), rifampicin (R), pyrazinamide (Z) + moxifloxacin
101
Standard course therapy for TB
RIPE for 2 months
RI for 4 months
102
What component of the RIPE therapy is best at killing rapidly multiplying bacteria
isoniazid
103
What TB medication is most likely to cause hepatitis
pyrazinamide
104
what TB drug is most likely to cause neuropathy
isoniazid
105
What TB drug is associated with optic neuropathy?
Ethambutol
106
Management of TB therapy induced hepatitis
If 2-5x normal, asymptomatic, monitor closely
If \>5x normal, or \>3x and symptoms, cease
107
What is the most common non-drug resistance in TB?
Isonaizid
108
rifampicin and CYP3A4
induces CYP3A4
109
What is contraindicated with rifamycin?
tenofivir alafenamide (tenofivir disproxil fumarate ok)
bictegraivir
elvitegravir
protease inhibitors are contraindicated with rifampicin but can be taken with a dose reduced rifabutin
110
What is the MOA of echinocandins and what are examples of them
Cell wall beta (1, 3) - glucan synthesis inhibitors
e.g. Caspofungin, anidulafungin, micafungin
111
What is the MOA of triazoles? (and examples)
endoplasmic reticulum ergosterol biosynthesis inhibitors:
- Inhibits C-14alpha demethylase required for ergosterol synthesis
e. g. fluconazole, itraconazole, voriconazole, posaconazole, ravuconazole
112
What is the MOA of amphotericine
plasmalemma ergosterol plasma membrane integrity
113
pharmacokinetics of conventional amphotericin B
Unknown - not affected by the hepatic or renal system and haemodialysis does not alter blood concentrations
BUT can cause nephrotoxocity
114
What is the clinical use of conventional amphotericin B
Not widely available in Australia:
* Selected cases of invasive candidiasis
* Cryptococcal meningitis (now L-AMB is first line)
* Empiric therapy in selected cases
Pros: broad spectrum of activity and resistance is slow to develop
Cons: drug toxicities limit efficacy/response
115
What is the general preferred polyene (antifungal)
Liposomal amphotericin B (compared with conventional amphotericin B):
* Less nephrotoxic
* Less infusion related side effects
* Similar efficacy
116
What is the indication for inhaled amphotericin B?
1. Prophylaxis in lung transplant patients
2. Occasionally in the haematology population if oral antifungals are contra-indicated and cannot have IV ampotericin B
117
Which anti-fungal has increased affinity for aspergillus?
Voriconazole - because it has the addition of a methyl group to propyl backbond of fluconazole and the substitution of a triazole moiety with a fluoropyrimidine group.
This results in an increased afinity for the 14-alpha-sterol demethylase enzyme in Aspergillus
118
Voriconazole toxicities
Elevation of LFTs
Photosensitive rash
Transient dose related visual disturbance in 8-10%
119
1st line therapy for definite or probably invasive aspergillosis
1st line - Voriconazole IV
2nd line - LAB
120
Initial therapy for candidaemia
1. Candida albicans
2. Other candida species
3. Critically ill candidaemia
1. fluconazole
2. anidulafungin
3. anidulafungin
121
subacute endocarditis most common organisms
viridans streptococci (17% of all IE)
Enterococcus faecalis (11 of all IE)
122
IVDU with pneumonia differential
infective endocarditis
(75% of R) IE have pneumonia/infective pulmnonary emboli)
123
what is a key cause of culture negative infective endocarditis and what is the next investigation to do?
Q fever - serology
others: bartonella, tropheryma whipplei, psittacosis, brucellosis
124
Viridans strep subacute endocarditis treatment
2 weeks IV penicillin + 2 weeks IV gentamicin or 4 weeks IV penicillin
Use vanc if MIC \>2mg/L
125
Treatment of enterococcal infective endocarditis
4-6 weeks of IV penicillin or amoxil/amp + gent
126
Treatment of staph IE
MSSA: 4-6 weeks of IV fluclox/1st gen cephalosporin
MRSA: Vanc 4-6 weeks
127
Uncomplicated tricuspid valve endocarditis treatment
2 weeks IV fluclox + gent
4 weeks if complicated (e.g. lung lesions, prosthesis, L side involvement)
128
Treatment of culture negative endocarditis
ceftriaxone 3-4 weeks + gentamicin 2 weeks
129
Indications for surgery in infective endocarditis
1. Heart failure
2. Paravalvular exdension
3. Uncontrolled infection/difficult organism (persistent bacteraenia \>10 days despite appropriate antibiotics; fungal/brucella/pseudomonas)
4. Recurrent embolic events despite appropriate antibiotics
130
Mean time to PJP after transplant
~20 weeks
131
Incubation period typhoid fever
up to 21 days
132
First line uncomplicated malasia
artemether-lumefantrine (po)
send line atovaquone-proguanil
133
adverse effects of artesunate
cerebellar ataxia, abdo pain/diarrhoea, increased ALT, delayed haemolysis
134
SE quinine
hypoglycaemia, hearing loss, increased QT, diarrhoea
135
Severe malaria treatment
IV artesunate
136
mutation assocaited with artesunate resistance
single point mutation in propellar region of P falciparum kelch protein on chromosome 13
137
Treatment for travellers' diarrhoea
mild diarrhoea - symptom management alone
blood, mucus, unwell, profuse diarrhoea then use antibiotics:
- azithromycin 1g stat or 500mg daily for 2 days
- Cipro 500mg bd for 2 days
138
Treatment of giardia lamblia
tinidazole 2g orally stat
139
zika and timing of conception/pregnancy
3 months for men, 8 weeks for women
140
what fetal deformity does zika cause and which trimester is associated with the highest risk?
microcephaly, trimester 1
141
4 criteria for dengue haemorrhagic fever
fever/recent history of acute fever
haemorrhagic anifestations
low platelet count \<100
objective evidence of leaky capillaries
142
What classes of drug inhibit the 30S ribosomal sub-unit?
aminoglycosides and tetracyclines
143
What is the mechanism of resistance for MSSA
alteration to the penicillin binding site
144
second gen cephalosporins examples and coverage
cefoxitin, cefotetan, cefuroxime
gram +ve, enterbacter, klebsiella, H. influenzae
145
what aminoglycoside is the worst for hearing?
amikacin
146
what antibiotic causes orange-pink discolouration of the urine?
rifamycins
147
what antibiotic can cause irreversibe aplastic anaemia with toxicity
chloramphenicol
148
MOA of linezolid
23S ribosomal RNA of the 50S subunit of the bacterial ribosome and prevents the formation of a functional 70S initiation complex which is an essential component of the bacterial translation process
149
MOA daptomycin
binds to **bacterial membrane**s and causes a rapid depolarisation of membrane potential in both growing and stationary phase cells. This loss of membrane potential causes inhibition of protein, DNA and RNA synthesis. This results in **bacterial cell death** with negligible cell lysis
150
what are enterococci intrinsicly resistant to?
cephalosplorins
151
what's the difference in cover for meropenem vs ertapenem
ertapenem has no pseudomonal cover
152
how are beta lactams excreted
renally excreted (except ceftriaxone)
153
what kind of VRE can teicoplanin treat
van B
154
what site of infection should daptomycin not be used?
lung - due to surfactant
155
linezolid SE
marrow suppression
peripheral neuropathy
dose and duration dependent - so try to keep duration \<2 weeks and monitor for SE
156
clinda spectrum of activity
gram positives and anaerobes
157
difference in spectrum of activity between ciprofloxacin and moxifloxacin
cipro has pseudomonas
moxi has strep and anaerobes
158
what broad spectrum antibiotic has poor protein carriage and what are the clinical indications
tigecyclines - not good for bacteraemias
159
what gram positive directed antibiotic is effective at managing biofilms and what are the clinical indications
rifampicin - good for prosthetic joints
160
