Infection Flashcards
(220 cards)
1
Q
What are the main agents of infection?
A
Bacteria Viruses Parasites Fungi Prions
2
Q
What are common tests used for viral detection?
A
PCR (ie molecular methods)
serology
antigen detection
3
Q
What are common tests for bacterial detection?
A
Microscopy (+ or - staining)
Culture (selective or non-selective)
4
Q
What are common bacterial features used for identification?
A
Morphological
Physiological
Biochemical
5
Q
What common tests used for parasitic detection?
A
Microscopy of parasitic life stages
Serology
6
Q
What are some of the basic infection control measures?
A
Handwashing
Decontamination (eg stethoscope, surfaces)
PPE
Isolation
7
Q
List some of the common samples collected for culture
A
Faecal specimen Throat swab Wound swab Urine sample Sputum sample Blood sample
8
Q
What are the main mechanisms of action of antibacterial drugs?
A
Inhibit cell wall synthesis
Affect protein synthesis
Affect nucleic acid synthesis
9
Q
What are the main classes of drugs to affect cell wall synthesis in bacteria?
A
- beta lactams
- glycopeptides
10
Q
What are the main types of beta lactams?
A
penicillins and cepharlosporins
11
Q
What are the main classes of drugs that affect protein synthesis in bacteria?
A
- aminoglycosides
- macrolides
- tetracyclines
12
Q
What are the properties and risks associated with cephalosporins?
A
broad spectrum antibiotics
can cause C. Difficile infections
13
Q
What are some of the macrolide drugs used in bacterial infections and when are they often used?
A
clarythromycin, erythromycin
alternative for penicillin if allergic
14
Q
What are the main classes of antibacterials which affect nuclear acid synthesis?
A
- trimethoprim and sulphamethoxazole (co-trimoxazole combined)
- fluoroquinolones
15
Q
What are examples of fluoroquinolones and their limitations?
A
Ciprofloxacin, levofloxacin
Ciprofloxacin affects cartilage growth, can’t be used in children
16
Q
What drug group is vancomycin part of, and what class of bacteria does it act on?
A
glycopeptide
Gram +ve bacteria
17
Q
What drug group is gentamycin part of, and what class of bacteria does it act on?
A
aminoglycoside
Gram -ve bacteria
18
Q
What are nitrofurantoin and nalidixic acid used for?
A
UTIs
19
Q
What is the main advantage of nitrofurantoin over nalidixic acid?
A
It is effective on some gram +ve and -ve organisms
20
Q
What class of bacteria does nalidixic acid act on?
A
gram -ve
21
Q
What drugs are known to cause liver and renal toxicity?
A
Aminoglycosides (gentamycin) and glycopeptides (vancomycin)
22
Q
What drugs are reserved for MRSA infections?
A
Linezolid and daptomycin
23
Q
What antibacterials are safe to give to pregnant women?
A
penicillins, cephalosporins, nitrofurantoin
24
Q
What are the main mechanisms of bacterial resistance?
A
- beta lactamase production
- PBP alteration
- vancomycin resistance (protein alteration)
25
What classes of drugs produce extended spectrum beta lactamases?
Gram -ve bacteria
26
What is the concern with carbapenemase producing bacteriaceae (CPE)
carbapenem is a broad spectrum antibiotic used for multi-drug resistant bacteria
if bacteria resistant to carbapenem, potentially no other drugs available to treat
27
What is the mechanism of action of penicillins?
they affect the synthesis of the peptidoglycan cell wall
28
What is the mechanism of action of glycopeptides?
they affect the synthesis at a stage prior to penicillins
29
What is the mechanism of action of nucleic acid inhibiting antibacterials, and give examples of drugs for each
- purine synthesis (trimethopriim, sulphamethoxaxole)
| - DNA affected directly (fluoroquinolones eg ciprofloxacin))
30
What is a commonly used drug for anaerobic bacterial infections?
Metronidazole
31
What are the properties of piperacillin?
It is a broader spectrum version of penicillin which is also active against pseudomonas
32
What are the main types of antifungal drugs?
Polyenes
Azoles
Echinocandins
Allylamines
33
What are the main types of polyene drugs and their properties? (administration, when it's used)
- Amphotericin B (toxic, IV for serious infections)
| - Nystatin (topical, non-serious infections)
34
What are the main actions of antifungal drugs and what are examples of drug classes for them?
- target ergosterol (polyenes, allylamines, azoles)
| - target glucan polysaccharide (echinocandins)
35
What is the mechanism of action of polyenes?
Target ergosterol on cell wall and make it permeable
36
What is the mechanism of action of allylamines and azoles?
Inhibit ergosterol synthesis
37
What is the effect of antiviral drugs on viruses?
Always virustatic, there are no virocidal drugs
38
What is the main drug for Herpes Simplex Virus?
Aciclovir
| Famciclovir
39
What is aciclovir used for?
Herpes simplex virus
| varicella zoster virus
40
What are the aciclovir analogues used to treat?
Ganciclovir - CMV
| Famciclovir - HSV and shingles
41
How is aciclovir activated, and what type of molecule is it?
Nucleoside analogue
| Prodrug - activated by thymidine kinase
42
What is the mechanism of action of Zidovudine?
Nucleoside analogue - acts on reverse transcriptase
43
What is Zidovudine used to treat?
HIV
44
What is commonly used to treat HIV?
A combination of different reverse transcriptase inhibitors
nucleoside reverse transcriptase inhibitors
non-nucleoside reverse transcriptase inhibitors
protease inhibitors
45
When is Foscarnet used?
Treating CMV, HSV, VZV infections resistant to aciclovir/ganciclovir/famciclovir
Foscarnet toxic for kidneys, only IV
46
What are examples of drugs used to treat Hepatitis B and C?
Interferon alpha
| Lamivudine
47
What are examples of Herpes viruses?
Cytomegalovirus
Herpes Zoster virus
Varicella Zoster virus
Epstein-Barr virus
48
What are the main classes of viruses treated with drugs?
Severe/life threatening viral infections
- HIV
- chronic hepatitis B/C
- Herpes viruses
49
What is lamivudine used for?
chronic hepatitis B
50
What is interferon alpha used for?
Hepatitis B and C
51
What is the combination of drugs often used for treating chronic hepatitis infections?
Interferon alpha + ribavarin
52
What is ribavarin used for?
combination with interferon alpha for chronic hep C
| may be used for respiratory RSV infection
53
What can be used to treat Influenza A or B in early stages?
Zanamavir
54
What is Zanamavir used for?
Treating Influenza A or B in early stages
55
What are the most common methods used to analyse the sensitivity of an organism to an antibiotic?
- automated methods
| - E test
56
How do trimethoprim, suxamethoxazole and co-trimoxazole act?
Affect purine synthesis
57
How do fluoroquinolones act and when are they used?
Directly affect nucleic acid synehtsis
| Pseudomonas infection, strep pneumoniae LRTI
58
What class of bacteria are always resistant to which type of drug?
Gram +ve streptotoccus - always resistant to gentamycin (aminoglycoside)
Gram -ve bacteria - always resistant to vancomycin (glycopeptide)
59
What are the main genetic mechanisms which allow bacteria to become resistant?
- spontaneous mutation of genetic code
| - spread of resistance (through transposons or plasmids)
60
How do cephalosporins change in properties with generations?
Newer generations have
- better gram -ve action
- worse gram +ve action
61
Can someone with a penicillin allergy also be allergic to cephalosporins?
Yes, about 10% of those allergic to penicillin
62
What antibiotic is associated with pseudomembranous colitis?
Clindamycin
Cephalosporins
Fluoroquinolones
63
What can pseudomembranous colitis be caused by?
A drug induced increase of C Difficile in the colon
64
What can be used to treat early stages of Influenza A and B
Zanamavir
| Oseltamivir
65
What are azoles often used for?
Yeast infections and some filamentous infections
66
What are allylamines often used for?
Dermatophytic infections
67
What are polyenes used for?
Amphoterycin B - serious infections (IV)
| Nystatin - yeast
68
What are echinocandins used for?
Serious fungal infections - expert advice only
69
What is flucloxacillin mostly used for?
Staphylococcal infections
70
What class of bacteria is amoxycillin most effective for?
Gram -ve
71
What is the main difference between Gram +ve and Gram -ve bacteria?
Gram +ve: thick peptidoglycan layer + inner membrane (2 layers)
Gram -ve: lipopolysaccharide layer + thin peptidoglycan layer + inner membrane (3 layers)
72
What is the main function of the bacterial capsule, what is its structure and what is it made of?
Stops the bacterium from being phagocytosed and digested.
slimy, forms biofilm
made of glycosaminoglycans (GAG)
73
What are the different terms for flagella and what ist their function?
Monotrichous
Amphitrichous
Lothotrichous
Peritrichous
used for motility
74
What is the purpose of fimbriae on a bacterium?
Stickiness - helps to adhere to surfaces
75
What is a plasmid?
A piece of bacterial DNA which can be injected into other bacteria
76
What is normal genetic division in bacteria called, and what does it result in?
Binary fission - two identical copies
77
What is a bacteriophage?
It's a virus that kills bacteria by injecting its DNA into them
78
What are the methods of DNA transfer among bacteria?
- Conjugation
- Transformation
- Transduction
79
What is the function of spores in bacteria?
they are produced by bacteria to survive in difficult environments
80
How are bacteria classified?
Genus - staphylococcus, streptococcus etc
| Species - aureus, epidirmidis, pneumoniae etc
81
What are the possible structures of a virus?
helical
icosahedral (20 sides)
complex
82
What are the ideal factors for eradication of a virus?
```
easy method for virus detection
effective treatment
effective prophylaxis (vaccines)
remove possible hosts
economical/political support
```
83
What are the aspects of a virus used to identify it?
mode of replication
shape/size
genome structure
envelope
84
What are the outcomes of a viral infection?
Resolution (plus or minus immunity)
latency
chronic infection
genetic changes (eg cancer)
85
What is the mode of replication of viruses?
Infect host cell
inject own DNA in host cell nucleus to make viral proteins and new viral nucleic acid strands
new viral nucleic acid/proteins assembled and leave the cell
86
Do all viruses have a lipid envelope?
No
87
What is a viral capsid?
a membrane that contains the viral genome
88
What are spike projections on viral lipid envelopes used for?
target for treatment
89
What is viral latency?
it's a stage after the initial infection during which the virus is dormant but can reactivate to cause disease
90
Does viral infection resolution always result in immunity?
no
91
what can be the result of genetic changes from a viral infection?
cancer (eg cervical from HPV)
92
How can a virus induce cancer in cells?
- induced cell proliferation
- reduced apoptotic measures
- damage from reactive oxygen species
93
How are viral infections prevented?
```
vaccination
prophylactic and post-exposure treatment
infection control
antenatal screening
blood/tissue/organ screening
```
94
What are the main three classes of fungi?
mushrooms
yeasts
moulds
95
What is the main difference between yeasts and moulds?
Yeasts grow as uni-cellular organisms
| Moulds have hyphae and are filamentous
96
What is dermatophytosis and what can it also be called?
ringworm infection
| tenia
97
what are examples of opportunistic fungal pathogens?
candida spp
aspergillus spp
dermatophytes
cryptococcus neoformans
98
which fungal infections are normally more serious?
candida infections
| aspergillus infections
99
what host factors contribute to fungal growth?
moist/warm environment
low immune system
broad spectrum antibiotic use
100
Are candida spp moulds or yeasts?
Yeasts
101
What is a unique feature of candida albicans?
it can grow hyphae in some environments
102
are aspergillus spp moulds or yeasts?
Moulds
103
Are cryptococci yeasts or moulds?
Yeasts
104
What are the main types of cryptococcus?
cryptococcus neoformans
| cryptococcus gattii
105
which main types of fungi are moulds?
aspergillus spp
| dermatophytes
106
Which main types of fungi are yeasts?
candida spp
| cryptococcus spp
107
Are dermatophytes moulds or yeasts?
moulds
108
What is a unique feature of aspergillus spp?
can invade blood vessels
109
What is a unique feature of cryptococcus?
it has a capsule
110
What is a unique feature of dermatophytes?
use skin keratin for nutrition
111
What is pityriasis versicolor caused by and what kind of fungus is it?
Malassezia spp - yeast
112
What are the main classes of parasites?
Protozoa
Helminths
Arthropods
113
What are the types of protozoa?
malaria
amebae
flagellates
114
What are the types of helminths?
Flatworm
roundworm
tapeworm
115
What are the types of arthropods?
mites
ticks
lice
116
What causes malaria?
Plasmodium spp
117
Which type of plasmodium is most fatal?
plasmodium falciparum
118
What is the lifecycle of the plasmodium spp?
sexual reproduction in mosquito gut
| injected in human blood, mature in liver, multiply in RBC
119
What are the most common protozoal infections?
malaria
amoebic dysentery
leishmaniasis
120
What is schistosomiasis caused by?
schistosomes that penetrate through skin
121
Where is schistosomiasis contracted?
swimming in fresh water
122
What immune reaction can helminth infections cause?
Eosinophilia
| elevated IgE
123
What is microscopy used for in diagnosing helminth infections?
identifying PCO (parasites, cysts, ova) in faeces
124
What causes an infection of leishmaniasis?
Sandfly bite
125
What does schistosomiasis affect?
Skin, urinary tract and intestine
126
What can leishmaniasis affect in terms of where in the body it can cause damage?
skin
| internal organs
127
Which type of bacteria are haemolytic?
Streptococci
128
What are the differences in haemolytic bacteria?
Alpha haemolytics - partially lyse blood
| beta haemolytics - fully lyse blood
129
What is the main feature to distinguish between staphylococci?
Coagulase test
130
Are coagulase negative bacteria harmful, are there exceptions?
No, but staph ludgunensis can cause infections if it gets into cannulas
131
What is the difference between staphylococcus and streptococcus?
Staphylo - clusters
| strepto - chains
132
What are the main shapes of gram positive bacteria?
Cocci
| Bacilli
133
What differentiates clostridium difficile from streptococci and staphylococci?
bacillus
| anaerobic
134
Which bacillus has a drumstick appearance?
clostridium tetanii
135
What are examples of bacteria which can't be identified from Gram stains?
AAFB
| spirochaetes
136
What is the only anaerobic Gram +ve bacterium?
Clostridium spp
137
Where can Staph aureus be found as a commensal?
Nose
Axilla
Genitaln/anal area
138
How can Staph aureus be identified?
Gram staining
| Coagulase test
139
What bacterium forms blue chains and creates a green hue in culture?
Strep pneumoniae
| partial (alpha) haemolytic
140
What bacterium forms blue chains and creates a seethrough area in culture?
Strep pyogenes
| total (beta) haemolytic
141
Which bacteria Gram -ve and also coagulase -ve?
Staph epidirmidis, staph lugdunensis
142
Where is staph lugdunensis normally found?
skin
143
What beta hemolytic group of bacteria does strep pyogenes class under?
Group A
144
What beta hemolytic group of bacteria does strep agalactiae class under?
Group B
145
What classes as Group D streptococci, but have now been renamed?
Enterococci
146
What is strep pneumoniae also known as?
Pneumococcus
147
What is strep viridans and what does it cause?
alpha hemolitic Gram +ve
| infective endocarditis
148
What is strep agalactiae known for?
serious neonatal infections
149
Where is clostridium difficile normally found?
In gut
150
Why is it called that, and why is that?
Difficile - difficult to culture
| because it's anaerobic
151
How do clostridium difficile and clostridium tetani cause damage?
Through toxin release
152
Where can clostridium perfringens be found normally and where can it be pathogenic?
Normally in gut
| can cause wound infections and gastroenteritis
153
Is clostridium spore forming?
Yes
154
What do neisseria spp, campylobacter, salmonella and pseudomonas aeruginosa have in common?
All gram -ve
155
What does neisseria meningitidis cause?
Meningitis
156
What does moraxella catarrhalis cause?
RTI
157
What do neisseria and moraxella have in common?
Gram -ve cocci
158
What are examples of gram negative bacilli?
```
Salmonella
E Coli
Shigella
Krebsiella
Pseudomonas
```
159
What are examples of curved bacilli?
Campylobacter
| Helicobacter
160
What does campylobacter cause and why?
Main cause of diarrhoea
| Found in chickens
161
What is the appearance of haemophylus influenzae?
mixed appearance (cocco-bacilli)
162
What can be used as a preliminary test for gram negative bacilli?
Lactose fermentation
163
Is E Coli a lactose fermenter?
Yes
164
Is Salmonella a lactose fermenter?
No
165
What is another name for gram negative bacilli?
Coliforms
166
What diseases can spirochaetes cause?
Leptospirosis
Lyme disease
Syphilis
167
can chlamydia spp be cultured?
no
168
what is the method used to identify chlamydia?
serology
169
where is porphorymonas found and what are its properties?
dental/periodontal abscess
| anaerobic gram -ve bacillus
170
How are mycobacteria identified?
ZN/auramine stain
| culture
171
How are spirochaetes identified?
serology
| nucleic acid amplification
172
What are some of the symptoms of malaria?
Flu-like
fever
rigors
173
What can be a symptom of entamoeba histolytica?
GI infections
| Liver abscess
174
What are some symptoms of leishmaniasis?
Skin/mucocutaneous lesions
| Visceral: fever, malaise, weight loss, enlarged spleen and liver
175
What can schistosomiasis cause?
```
itching
urinary and gastrointestinal infections
bladder cancer
haematuria
delayed fever
```
176
where in the body are nematodes found?
intestine and lungs
177
What are potential symptoms of nematode infection?
asymtomatic
| some respiratory symptoms
178
What type of worms are ascaris lumbricoides?
Nematodes
179
What is an exotoxin?
A toxin produced and released outside of the bacterium
180
What is an enterotoxin?
A toxin which is produced by a bacterium and is released into the GI tract
181
What is an endotoxin and where can it be found?
A toxin which makes up part of the bacterial structure (eg LPS complex in Gram -ve bacteria)
182
What are the two properties a pathogen needs to cause disease?
Infectivity
| Virulence
183
What is meant by bacterial infectivity and how is it achieved?
The ability to settle in an organism
"stickiness"
resistance to acid (capsule)
184
What is meant by bacterial virulence, and what are some factors which contribute to it?
the ability to cause disease once settled into a host
invasiveness
toxin production
ability to evade immune system
185
Which class of bacteria contains endotoxins?
Gram -ve bacteria
186
What are the main ways viruses cause disease?
- killing the cells they infect
- changing the cells they infect (eg tumour inducing)
- causing an immune reaction
187
Why is Staph aureus a likely secondary bacterial RTI after a viral infection?
Because it's a nose commensal, and viral infections can destroy respiratory epithelium allowing S aureus to get into the airways
188
What is an enterovirus and what can it cause?
A virus that only gets in through GI tract but can spread to any organ, causing infections in other parts of the body
189
Where does Herpes virus stay during its latency period?
Ganglia
190
How can viruses get into the body?
```
skin
respiratory
arthropod
GI
genital
urinary
```
191
What are the roles of complement and when is it activated?
activated by combination of IgM with IgG
- opsonization
- kill gram -ve bacteria
- chemotaxis
192
What is the role of antibodies?
destroy bacteria/viruses
opsonization
stops organisms from attaching
193
Where does humoral immunity occur?
extracellularly
194
Where does cell mediated immunity occur?
intracellularly
195
What is the difference between T4 and T8 cells?
- T4 are helper cells
| - T8 are cytotoxic cells
196
What are the subtypes of adaptive immunity and what lymphocytes do they involve?
```
Humoral immunity (B cells)
cell-mediated immunity (T cells)
```
197
What types of infections is the humoral immune system good for?
Bacterial infections
| extra-cellular infections
198
What types of infections is the cell-mediated immune system good for?
viral/fungal infections
| intra-cellular infections
199
What is antigenic drift and shift?
Drift - slow changes to virus strain
| Shift - sudden change in virus strain
200
What is the principle of giving passive immunity?
Giving someone premade antibodies/immunoglobulins to fight infection
201
What is the principle of giving active immunity?
Giving someone mild version of antigen, so the body will produce their own antibodies/immunoglobulins against it
202
What is an advantage of giving passive immunity?
Immediate effect
203
What is a disadvantage of giving passive immunity?
body may cause immune reaction to the injected foreign antibodies (serum sickness or arthus reaction)
204
What are the types of vaccine available?
live attenuated
killed
toxoid
subunit
205
What is a subunit vaccine and what are available examples?
particles from virus or resembling virus
- HPV vaccine
- Hep B surface antigen vaccine
206
How is an attenuated vaccine made?
Grown in animals so that when it's injected back into humans it doesn't thrive as well
207
What is a toxoid vaccine?
It's a toxin that has been treated with formalin so it's not toxic anymore
208
What are some contraindications to vaccines?
immunocompromised
fever
pregnancy (no live vaccine)
allergy
209
What is the concept of herd immunity?
individuals who cannot be vaccinated will benefit from the immunity of others around them
210
In which vaccine are T cells essential?
BCG (anti TB)
211
What are checkpoint inhibitors and why could they be targeted in cancer?
proteins that stop T cells from attacking other cells
| they could be used for the body to elicit an immune response against cancer cells
212
What is POCT and what is it useful for? What are examples of POCT?
Point of care Testing
| Useful for immediate test results (eg glucose, blood gas, urine tests)
213
What is the disadvantage of POCT?
Not always accurate
214
What are some of the common methods of identification which can help to determine the identity of a body?
```
Sex
Age
Height
Medical/dental records
Tattoos/scars
Finger prints
DNA
Hair/eye colour, facial hair
```
215
What is rigor mortis and when does it occur?
Stiffening of muscles after death 5-12 hours after death
216
What is hypostasis and what causes it?
Areas of pallor with bruising around them
| Caused after death by blood pooling with gravity
217
What is saponification and what is it caused by?
Adipoceres formation by fat cells invading tissue after death
218
What are the different types of decomposition?
```
Putrefaction
Saponification
Mummification
Maceration
Skeletonisation
```
219
What can putrefaction be caused by?
Bacterial infestation
| Autolysis
220
What is a general rule of thumb which can be used to estimate time of death?
Temperature drop - 1C per hour
