Infectious Disease Flashcards
(122 cards)
1
Q
How does addition of beta-lactamase inhibitor broaden spectrum of amoxycillin?
A
Adds MSSA, gram neg and anaerobic cover
2
Q
What is the main addition bacterial cover achieved by Tazocin rather than Augmentin?
A
Pseudomonas
3
Q
What is the mechanism of resistance in ESBL?
A
Plasmid-mediated resistance - acquired, mediated by DNA molecule within a cell which is separate to chromosomes
4
Q
What is the benefit in coverage of ceftazidime over ceftriaxone?
A
Pseudomonal cover
5
Q
What are the main differences between meropenem and ertapenem? (2)
A
Ertapenem once daily dosing
Ertapenem does not cover pseudomonas
6
Q
What bacteria is teicoplanin used to treat?
A
Van B VRE
7
Q
What site of the body does daptomycin NOT work in?
Why?
A
Lung
Inhibited by lung surfactant
8
Q
What does daptomycin cover?
A
Gram positives, including VRE
9
Q
2 major site effects of linezolid?
A
Peripheral neuropathy
Marrow suppression
10
Q
What does aztreonam cover?
A
Gram negatives, pseudomonas
11
Q
What is the mechanism of resistance in ESCAPPMs?
A
Chrosomally-mediated through AmpC
Gram negatives with inducible cephalosporinase
12
Q
Why can tigecycline not be used in bacteraemia?
A
Large volume of distribution, so does not reach high enough concentrations in blood
13
Q
Why is rifampicin used in othopaedic infections?
A
It is active against biofilm
14
Q
Which is preferable in penicillins -
- Higher dose less frequent
- Lower dose more frequent
A
- Lower dose more frequently -> to optimise time above MIC
15
Q
What is main consideration in dosing of aminoglycosides?
A
Area under curve -> higher dose less frequent (i.e. maximal concentration)
16
Q
What is the reason for giving antibiotics as prolonged infusions in difficult to treat infections?
A
To optimise time above MIC
17
Q
What is first line treatment for invasive aspergillosis?
A
Voriconazole
18
Q
1st line for candidaemia?
A
Echinocandins
19
Q
1st line for cryptococcal meningitis?
A
Ambisome (liposomal amphotericin)
20
Q
Which strain of malaria is most benign usually?
A
P. malariae
21
Q
Which strains of malaria can cause late relapses?
Why?
A
P. ovale, P. vivax
Form hypnozoites in the liver
22
Q
What is the most common pathogen found in Traveller’s diarrhoea?
A
Enterotoxigenic E.Coli
23
Q
What is the preferred treatment for candida krusei?
A
Amphotericin B
24
Q
Which anti-TB drug has the highest rate of mono-drug resistance?
A
Isoniazid
25
What condition is strep bovis endocarditis closely associated with?
Bowel malignancy
26
What is the most likely organism for native valve endocarditis in IVDU?
Staph aureus
27
What is the commonest specific diagnosis made in febrile returned travellers?
Malaria
28
Why does amoxycillin not work to treat Klebsiella?
All Klebsiella are intrinsicially resistant due to narrow spectrum beta lactamase in genome
29
What is the class of antibiotics usually used to treat ESBL infections?
Carbapenems
30
What is the broad empiric management of suspected CRE infection?
Meropenem via extended infusion PLUS amikacin or colistin
31
How do penicillin abx work?
Bind with penicillin-binding proteins on cell wall to inhibit cell wall synthesis
32
Which cephalosporins have pseudomonal cover? (2)
Cefepime
| Ceftazadime
33
Which beta lactam does NOT have strep cover?
Aztreonam (only gram neg cover)
34
How does metronidazole work?
Captures electrons, which creates free radicals and destabilises bacterial DNA
35
Which antibiotic can cause metallic taste?
Metronidazole
36
Name 4 Abx with equal PO / IV bioavailability
Quinolones
Metronidazole
Bactrim
Doxycyline
37
Which VRE active antibiotic has equivalent PO = IV bioavailability ?
Linezolid
38
What is the mechanism for VRE resistance?
Peptidoglycan residue D-ala-D-ala changing to D-lac, so reducing affinity of binding to vancomycin
39
What does daptomycin cover?
VRE
| MRSA
40
What are 2 unique adverse effects of daptomycin?
Rhabdomyolysis
| Eosinophilic pneumonia
41
Which two classes of ABx cause ototoxocity with prolonged dose?
Aminoglycosides
| Macrolides
42
Which antibiotics inhibit bacterial DNA gyrase?
Fluoroquinolones
43
Which abx causes achilles tendinopathy?
Fluoroquinolones
44
What is the only oral anti-pseudomonal agent?
Ciprofloxacin
45
What is the 1st line bx for Nocardia?
Bactrim
46
What does mutation in the rpoB gene in bacteria cause?
Rifampicin resistance
47
What does erm gene mutation in bacteria cause?
Macrolide resistance
48
What are ESBLs generally resistant to?
Penicillins and up to third generation cephalosporins, aztreonam
49
What does AmpC gene in bacteria confer resistance to?
```
Penicillins
Cephalosporins (except cefepime)
```
50
What is the empiric abx management of traveller's diarrhoea?
Azithromycin
51
What is treatment for suspected giardia?
Tinidazole
52
What is the main differential for febrile returned traveller when presenting <2 weeks post return?
Dengue fever
53
When does the critical phase of dengue occur?
After fever subsides
54
What test for dengue is most helpful to diagnose in acute phase?
NS1Ag
55
What condition in febrile returned travellers is associated with relative bradycardia?
Typhoid
56
What is 1st line treatment for severe typhoid?
Ceftriaxone
57
What is the 1st line treatment for severe falciparum malaria?
IV artesunate
58
What treatment is added to ACT for P.vivax / P.ovale strains?
Why?
What must be checked prior?
Primaquine
Required to eliminate dormant liver parasites, for relapse prevention
G6PD deficiency must be excluded
59
What is the standard treatment for uncomplicated malaria?
Artemether + lumefantrine
60
What are 4 criteria which define severe dengue?
Plasma leakage resulting in shock
Accumulation of serosal fluid sufficient to cause respiratory distress
Severe bleeding
Severe organ impairment
61
What is the key lab feature which indicates impending critical dengue infection?
Increasing haematocrit level alongside rapid decrease in platelet count
62
What are the three Cs of measles presentation?
Cough, coryza, and conjunctivitis
63
What is the most common cause of traveller's diarrhoea persisting beyond 2 weeks?
Giardia
64
What is the classic lab finding in strongoloides?
Eosinophilia
65
Homozygotes for what genetic mutation are essentially resistant to HIV?
CCR5 D32 homozygotes
66
Commonest cause of death in HIV positive people?
CV disease
67
When should ART be started in someone who is found to be HIV positive?
As soon as possible after diagnosis, in EVERYONE
Opportunistic infections can delay this, due to risk of IRIS
68
Which classes of ART should be involved at time of therapy initiation?
Integrase inhibitors +
Nucleotide/side reverse transcriptase inhibitors
Usually INSTI + 2 NRTIS
69
What is the role of cobicistat in ART?
Pharmaco-enhancer, by inhibiting CYP450 3a enzyme. Increases effective dose of certain ART
70
Which ART has risk of hypersensitivity in those with HLA -B5701?
Abacavir (NRTI)
71
Which drug should be involved in treatment if concomitant HBV?
Tenofovir
72
What defines virological failure in ART?
HIV RNA >200 copies after 24 weeks on treatment
73
What are 2 main toxicities associated with Tenofovir?
Renal -> Fanconi's, decline in eGFR
| Bone -> osteoporosis
74
Other than hypersensitivity, what is the other major side effect of Abacavir?
CV risk -> elevated AMI risk
75
Which class of ART cause increased CV risk and increase lipids?
Protease inhibitors
76
What is the risk of dolutegravir in pregnancy?
Increased risk of neural tube defects
77
What, aside from cobicistat, is often used as a drug booster / pharmaco-enhancer?
Ritonavir - protease inhibitor which potently inhibits CYP3A4
78
What type of sexual exposure with a known HIV positive person would NOT warrant post-exposure prophylaxis, even with unknown viral load?
Oral intercourse
79
What distinguishes hospital-acquired MRSA from nmMRSA?
Most nmMRSA strains are susceptible to non-beta lactam abx, like Bactrim, Clindamycin, macrolides
80
What is the significance of Panton-Valentine leukocidin cytotoxin in nmMRSA?
Confers enhanced virulence
81
At what MIC is VISA defined?
What change is seen within the bacterial cell?
What is the preferred treatment?
4-8 microg / ml
Thickened cell wall
Linezolid
82
What are the preferred Abx options for VRE Rx? (3)
Linezolid
Daptomycin
Tigecycline
(teicoplanin is not very effective)
83
What is the change in the vancomycin binding site which confers vanc resistance?
D-ala-D-ala to D-ala-D-lac
84
What is the main toxicity to be aware of with combination therapy with Vancomycin + Tazocin?
Renal toxicity
85
What is the biggest risk factor for TB reactivation?
HIV infection
86
Most common AEs from Rifampicin?
Drug interactions (potent CYP inducer)
Hepatitis
Thrombocytopaenia
87
Most common AEs from Isoniazid?
hepatitis, rash, neuropathy (give pyridoxine to minimise risk)
88
Pyrazinamide AEs?
Hepatitis (most likely culprit for deranged LFTs)
skin
gout
89
Ethambutol AEs?
Optic neuropathy
90
Which major TB drugs need to be dose-adjusted in renal impairment?
Pyrazinamide + ethambutol
91
What defines MDR in TB?
Resistance to rifampicin AND isoniazid
92
What defines XDR in TB?
Resistance to rifampicin AND isoniazid, plus quinolones and injectables
93
Which parasitic illness is associated with bladder carcinoma?
Schistosomiasis
94
What is the way to differentiate between Nocardia and Actinomyces in the lab?
Nocardia retains its stain on modified acid-fast stain
95
What are the 4 key types of clostridium bacteria?
Perfringens
DIfficile
Tetani
Botulinum
96
What type of paralysis does tetanus cause, vs botulism?
Tetanus -> spastic paralysis
Botulism -> flaccid paralysis
97
What is the difference in appearance on culture between staph and strep / enterococcus?
Staph is in clusters
Strep and enterococcus are in chains
98
What are some key coagulase-negative staph? (3)
What is their clinical significance?
Staph epidermidis
Staph saprophyticus (UTI)
Staph lugdenensis
Part of normal skin flora, can be commonly found as contaminants in BCs. Can cause clinically significant infection with IE, sepsis.
People at particular risk -> prosthetic devices, immunocompromise
99
Which coagulase negative staph has a tendency to behave with as much virulence as staph aureus?
Staphylococcus lugdunensis
100
What is Group A strep also known as?
What kind of infections can it cause?
Strep pyogenes
Throat, soft tissue
Can lead to immunological sequelae e.g. rheumatic fever, GN
101
What is group B strep also known as?
What is its clinical significance?
Strep agalactiae
Colonises the human genital and gastrointestinal tracts and the upper respiratory tract in young infants. Thus can cause serious infections in neonates, pregnant women
102
What are two classic presentations of rickettsial infections?
Spotty rash plus fever
Eschar at bite site
103
Name three important spirochetes
Syphilis
Leptospirosis
Borrelia (Lyme disease)
104
What is the mechanism of penicillin resistance when it occurs in Strep pneumoniae?
Altered PBPs
105
What is the usual mechanism of resistance in metallo-beta-lactamases e.g. New Delhi M?
Plasmid mediated
106
What bugs is colistin used against?
Resistant gram negatives
NO gram positive activity
107
Which strain of flu is Tamiflu more effective against?
Influenzae A
108
Name indications for surgery in IE? (5)
- Heart failure
- Paravalvular extension
- Persistent bacteraemia >10 days despite appropriate Abx
- Resistant organisms (pseudomonas etc)
- Recurrent embolic events despite Abx
109
Which virus causes Kaposi's sarcoma?
Human herpes virus 8 (HHV-8)
110
What bacteria causes the Plague?
Yersinia Pestis
111
How is the common cold spread (mode of transmission)?
Droplet spread
112
What is the mode of transmission of TB?
Airborne spread
113
What is the phenomenon responsible for influenzae pandemics?
Antigenic shift
114
Which is the organism involved in meningitis, in which it has been shown that steroid treatment has mortality benefit?
Pneumococcus
115
Which antibiotic is added in Toxic Shock Syndrome for its supposed anti-toxin effect?
Clindamycin
116
What is the key factor in determining risk of an occupational HBV exposure leading to infection?
Source HBeAg positivity
117
What are the recommendations for PEP following occupational HIV exposure?
2 drugs if source undetectable or very low risk exposure
3 drugs if source detectable / higher risk exposure
118
What is the gene which confers colistin resistance?
mcr-1
119
What is the first line therapy for candida auris?
Echinocandins
120
What infection is a major cause of portal HTN and pulmonary HTN worldwide?
Schistosomiasis
121
What is 1st line treatment for strongyloides?
Ivermectin
122
MRSA mechanism of resistance?
MEC-A gene - alters PBP so that it is resistant
