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Principles of Disease > Infection > Flashcards

Flashcards in Infection Deck (220):
1

What are the main agents of infection?

Bacteria
Viruses
Parasites
Fungi
Prions

2

What are common tests used for viral detection?

PCR (ie molecular methods)
serology
antigen detection

3

What are common tests for bacterial detection?

Microscopy (+ or - staining)
Culture (selective or non-selective)

4

What are common bacterial features used for identification?

Morphological
Physiological
Biochemical

5

What common tests used for parasitic detection?

Microscopy of parasitic life stages
Serology

6

What are some of the basic infection control measures?

Handwashing
Decontamination (eg stethoscope, surfaces)
PPE
Isolation

7

List some of the common samples collected for culture

Faecal specimen
Throat swab
Wound swab
Urine sample
Sputum sample
Blood sample

8

What are the main mechanisms of action of antibacterial drugs?

Inhibit cell wall synthesis
Affect protein synthesis
Affect nucleic acid synthesis

9

What are the main classes of drugs to affect cell wall synthesis in bacteria?

- beta lactams
- glycopeptides

10

What are the main types of beta lactams?

penicillins and cepharlosporins

11

What are the main classes of drugs that affect protein synthesis in bacteria?

- aminoglycosides
- macrolides
- tetracyclines

12

What are the properties and risks associated with cephalosporins?

broad spectrum antibiotics
can cause C. Difficile infections

13

What are some of the macrolide drugs used in bacterial infections and when are they often used?

clarythromycin, erythromycin
alternative for penicillin if allergic

14

What are the main classes of antibacterials which affect nuclear acid synthesis?

- trimethoprim and sulphamethoxazole (co-trimoxazole combined)
- fluoroquinolones

15

What are examples of fluoroquinolones and their limitations?

Ciprofloxacin, levofloxacin
Ciprofloxacin affects cartilage growth, can't be used in children

16

What drug group is vancomycin part of, and what class of bacteria does it act on?

glycopeptide
Gram +ve bacteria

17

What drug group is gentamycin part of, and what class of bacteria does it act on?

aminoglycoside
Gram -ve bacteria

18

What are nitrofurantoin and nalidixic acid used for?

UTIs

19

What is the main advantage of nitrofurantoin over nalidixic acid?

It is effective on some gram +ve and -ve organisms

20

What class of bacteria does nalidixic acid act on?

gram -ve

21

What drugs are known to cause liver and renal toxicity?

Aminoglycosides (gentamycin) and glycopeptides (vancomycin)

22

What drugs are reserved for MRSA infections?

Linezolid and daptomycin

23

What antibacterials are safe to give to pregnant women?

penicillins, cephalosporins, nitrofurantoin

24

What are the main mechanisms of bacterial resistance?

- 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