Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Phase 2a > ICS Microbiology > Flashcards

ICS Microbiology Flashcards

(305 cards)

Start Studying
1
Q

What is a pathogen?

A

Organism that causes or is capable of causing disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a commensal?

A

Organsim which colonises the host but causes no disease in normal circumstances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is an opportunistic pathogen?

A

Microbe that only causes disease if host defences are compromised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is virulence?

A

The degree to which a given organism is pathogenic/ any strategy to achieve this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is asymptomatic carriage?

A

When a pathogen is carried harmlessly at a tissue site where it causes no disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the shape of bacilli?

A

Rods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the shape of cocci?

A

Round, circular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are diplococci?

A

Pairs of cocci

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the difference between gram positive and gram negative bacteria?

A

Gram positive= Single membrane, large amount of peptidoglycan on outer surface. do not have endotoxin
Gram negative= Double membrane, smaller amount of peptidoglycan between membranes, The outer membrane has lipopolysaccharide which the immune system can react to (Endotoxic shock)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How can you differentiate between gram positive and gram negative bacteria?

A

Gram stain
Apply a primary stain such as crystal violet, add iodine, decolourise and stain with counterstain
Gram positive= Purple
Gram negative= Red/pink

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does gram stain differentiate?

A

Gram positive and gram negative
Gram positive= Purple
Gram negative= Red/pink

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does ziehl-neelsen stain differentiate?

A

Mycobacteria (rods) that don’t take up gram stain
e.g. M. TB, M. Leprae, M. Ulcerans
Acid-fast bacilli: Red
Non acid-fast bacilli: Blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do you differentiate acid-fast bacilli from non acid-fast bacilli?

A

Ziehl-Neelsen stain for mycobacteria
Acid-fast bacilli: Red
Non acid-fast bacilli: Blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Name an anaerobic gram negative cocci

A

Viellonella

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Name an aerobic gram negative cocci

A

Neisseria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name a gram positive aerobic cocci

A

Strep or staph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Name a gram positive anaerobiccocci

A

Peptostreptococcus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Name a gram positive aerobic bacilli

A

Corynebacterium, listeria, or bacillu

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Name a gram positive anaerobic bacilli

A

Clostridium or propionibacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Name a gram negative aerobic bacilli

A

Vibrio, Escherichia, salmonella, shigella, citrobacter, haemophillius, Helicobacter, campylobacter, pseudomonas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Name a gram negative anaerobic bacilli

A

Bacteroides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How can you differentiate between staphylococci and streptococci?

A

Catalase test

  • Add h2o2 and look for bubbling
  • Staph are catalase positive
  • Strep are catalase negative
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How can you differentiate between staph. Aureus and other staph?

A

Coagulase test

  • Staph. aureus= Coagulase positive (clumping)
  • Other staph.= Coagulase negative (no clumping)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How can you differentiate salmonella and shigella?

A

XLD Agar

  • Salmonella- Red/ Pink colonies with some black spots
  • Shigella- Red/ Pink colonies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How can you differentiate lactose fermenting bacteria from non lactose fermenting bacteria?
MacConkey Agar - Lactose fermenting= Red/pink - Non-lactose fermenting= White/transparent
26
What does MacConkey agar differentiate?
Lactose fermenting from non-lactose fermenting bacteria Only grows gram-negative bacteria
27
Name a lactose fermenting enterobacteria
E. coli, | Klebsiella pneumoniae
28
Name some non-lactose fermenting enterobacteria
Salmonella spp., shigella spp.
29
What is the optimum temperature of a bacteria?
-80 - 80 degrees (or up to 120 for spores)
30
What is the optimum pH for bacteria?
4-9
31
How do bacteria divide?
Binary Fission
32
What are endotoxins?
Component of the outer membrane of gram negative bacteria- lipopolysaccharide Only produced by bacteria, mainly gram neg bacteria
33
What are exotoxins?
Secreted from gram positive and gram negative bacteria- Proteins Produced by mainly gram positive bacteria
34
Can endotoxins or exotoxins be converted to toxoids?
Exotoxins
35
What happens in transcription?
RNA polymerase acts on the bacterial chromosome to form mRNA
36
What genetic variations can occur in bacterial genetics?
Mutations can occur on the bacterial chromosome: Base substitution, deletion, insertion. Mutations can cause antibiotics to be ineffective.
37
What are plasmids?
small circular pieces of DNA. Many plasmids carry antibiotic resistance genes.
38
What is transformation?
The genetic alteration of a bacterial cell via the uptake of an exogenous substance e.g. Via plasmid
39
What is transduction?
The process by which foreign DNA is introduced into a bacteria via vector or virus
40
What is conjugation?
The transfer of genetic material between bacterial cells by direct cell-cell contact
41
How do you perform a haemolysis test?
Put streptococcal samples on the blood agar Alpha haemolysis= An indistinct zone of partial destruction of red blood cells, often accompanied by a greeenish discolouration beta haemolysis= A clear colourless zone around the colonies (complete lysis) Gamma haemolysis= No change
42
Which bacterias are beta haemolytic?
Strep. Pyogenes, Strep. Aureus
43
Which bacterias are alpha haemolytic?
Strep pneumonia, strep viridans, oral strep
44
Which bacterias are gamma haemolytic?
Strep. Bovis
45
How can you differentiate between strep?
Haemolytic test | Optochin test
46
What does the optochin test do?
Differentiate between different streptococcus
47
What does the oxidase test do?
Test if the microorganism contains a cytochrome oxidase Oxidase postive= Blue= Bacteria is aerobic Oxidase negative= No colour change= Bacteria may be aerobic or anaerobic
48
What is coagulase?
An enzyme produced by bacteria that clots blood plasma. Fibrin clot formation around bacteria may protect from phagocytosis.
49
Do strep. or staph. appear as clusters?
Staph. appears as clusters
50
Name a staph. Aureus associated condition
Would infections, abscesses, osteomyelitis, scalded skin syndrome, toxic shock syndrome, food poisoning
51
What virulence factors are produced by staph. aureus?
Pore-forming toxins, Proteases
52
How is staph. Aureus infection normally treated?
flucloxacillin
53
What type of bacteria appears as clusters of cocci?
Staphylococcus
54
What type of bacteria appears as chains of cocci?
Streptococcus
55
What is lancefield grouping?
A method of differentiating beta haemolytic bacteria | - An antiserum is added to a suspension of each group= clumping indicated recognition
56
What are some associated conditions to staph. Aureus?
Wound infections, abscesses, Osteomyelitis, scalded skin syndrome, toxic shock syndrome, food poisoning
57
How can staph. Aureus be treated?
Flucloxacillin
58
What does MRSA stand for?
Methicillin resistant staphylococcus aureus
59
What are some associated conditions to staph. epidermis?
Opportunistic infections in prosthetic limbs and catheters
60
Name an associated condition to staph. Saprophyticus
Acute cystitis
61
How can streptococcus be differentiated?
Haemolysis Lancefield typing Biochemical properties
62
What infections are caused by strep. pyogenes?
Wound infections such as cellulitis, tonsillitis, pharyngitis, otitis media, scarlet fever
63
What infections are caused by strep. Pneumoniae?
Pneumonia, Otitis media, sinusitis, meningitis
64
Name some pre-disposing factors for strep. pneumoniae infection
Impaired mucous trapping Hypogammaglobinaemia Aslenia Very young
65
What is the clinical presentation of diptheria
``` Thin greyish film on tonsils High temp Nausea Sore throat Headache Difficulty swallowing ```
66
What infection does corynebacterium diptheriae cause?
Diptheria
67
What is lipopolysaccharide?
An endotoxin | Forms the outer leaflet of the outer membrane of gram-negative bacteria
68
What are the three major components of lipopolysaccharides?
Lipid A- The toxic portion of LPS Core (R) Antigen- Short chain of sugars, some are unique to the LPS Somatic (O) antigen- A highly antigenic repeating chain of oligosaccharides
69
What is H antigen?
Flagellum
70
What are the major groups of enterobacteria?
E coli Shigella Salmonella
71
Which enterobacterias are motile?
E coli Salmonella (Shigella is not)
72
How is E coli differentiated from shigella and salmonella?
E coli uses lactose so will show positive on MacConkey-Lactose agar
73
What infections are caused by pathogenic E coli strains?
``` Wound infections UTIs Gastroenteritis Travellers diarrhoea Bacteraemia Meningitis ```
74
What infection does shigella infection cause
Damage to large intestinal mucosa, causing acute infection of the large intestine, severe bloody diarrhoea and frequent passage of stools (Normally self limiting)
75
How does shigella infection spread?
Person-to-person or via contaminated water or food
76
What is shiga toxin?
A toxin that shigella releases Disrupts protein synthesis by blocking specific bond formation, resulting in necrosis This results in kidney failure
77
Briefly describe gastroenteritis
- Often a salmonella infection - Frequent cause of food poisoning from milk/ poultry - Neutrophil-induced tissue injury due to inflammatory response - Fluid and electrolyte loss resulting in diarrhoea - Inflammation/necrosis of gut mucosa
78
Briefly describe enteric fever
- Typhoid - Caused by salmonella - Spread faecal-oral - Fever, headache, dry cough, splenomegaly, diarrhoea - Bacteria may migrate into cell membranes, and spread systemically via lymph nodes - Can result in septicaemia and massive fever
79
Briefly describe Cholera
- Caused by vibrio cholerae - Transmitted via faecal-oral route - Results in voluminous watery stools - Severe dehydration and death - Can be 80% treated with oral rehydration
80
What infections could be caused by pseudomonas aeruginosa?
UTIs, Keratitis | Systemic infection in immunocompromised
81
How can you grow haemophilius influenzae?
Chocolate agar (It is fastidious)
82
What are the two major neisseria bacterias?
N. Meningitidis, N. Gonorrhoeae
83
What infection is caused by bordetella pertussis?
Whooping cough - Highly contageous - Non specific flu-like symptoms followed by paroxymal coughing
84
What bacteria is the most common cause of food poisioning?
Campylobacter | Salmonella is second most common
85
What diseases can be caused by H. pylori?
Gastritis Peptic ulcer disease Gastric adenocarcinoma
86
What bacteria is the most common cause of STD?
Chlamydia trachomatis
87
What are the two developmental stages of chlamydia?
Elementary bodys (round, infectious), and reticulate bodies (pleomorphic and non-infectious, but replicate)
88
List some gram negative bacterias that cause STD
Neisseria Gonorrhoeae Chlamydia trachomatis Treponema Pallidum (Syphilis)
89
List some gram negative bacterias that cause UTIs
Some E. coli serotypes Proteus mirabilis Klebsiella pneumoniae
90
List some gram negative bacterias that can cause meningitis
N. Meningitidis Some E.coli serotypes Haemophilius influenzae
91
List some gram negative bacterias that can cause sepsis
N. Meningitidis E.coli and K. Pneumoniae Pseudomonas aeruginosa
92
List some gram negative bacterias that can cause GI infection
``` Vibro Cholerae (Cholera) Shigella dysenteriae (Dysentry) H. Pylori ( Gastritis, peptic ulcers) S.enterica (food poisoning) Campylobacter Jejuni (Food poisoning) ```
93
Why are fungal infections rare in healthy hosts?
They can't grow at 37 degrees and can't evade the adaptive/innate immune response
94
Name a fungal skin infection
Athletes foot | Ring worm
95
List some invasive fungal diseases
Candidasis Aspergillus Pneumocystitis Pneumonoa Cryptococcosis
96
What is 1,3 B-D Glucan?
The cell wall component of many fungal cell walls, which is released into serum during invasive infection Can be detected to see fungal infections
97
What is onychomycosis?
Very common fungal infection of the nail
98
What is pneumocystis pneumonia?
Fungal infection of the lungs
99
What does flucytosine target?
Targets the DNA/RNA synthesis of fungi
100
What is voriconazole used for?
Moulds
101
What things can we get samples of?
Skin swab of infected area Secretions= Faeces, urine, mucous etc Blood
102
List the different types of agar
``` Blood agar Chocolate agar CLED agar MacConkey agar Gonococcus agar XLD agar Sabouraud's agar ```
103
What is chocolate agar?
Contains blood agar heated to 80 degrees for 5 minutes to release some nutrients into the agar and make it easier to grow certain organisms that do not grow easily
104
What is blood agar?
Contains sheep/horse blood and provides a good medium for growing many different types of bacteria
105
What is CLED agar?
Cysteine lactose electrolyte deficient agar is a relatively non-inhibitory growth medium often used to differentiate microorganisms in urine. It allows classification of lactose-fermenting (yellow) and non-lactose fermenting (blue) gram negative bacilli,
106
What is MacConkey Agar?
MacConkey agar is agar designed to grow gram negative bacilli and differentiate them. It grows lactose fermentors pink, and non-lactose fermentors yellow/colourless
107
What is gonococcus agar?
Agar that contains growth factors to promote the growth of neisseria gonnhorea and other neisseria spp.
108
What is XLD agar?
Xylose lysine deoxycholate agar is a very selective growth medium used to isolate salmonella spp., and shigella spp. It has a pH indicator. Shigella are red and salmonella are red with black centres.
109
What is Sabouraud's agar?
User to culture fungi. Inhibition of bacteria is aided by the presence of antibiotics in the agar.
110
How does staph aureus appear in blood agar?
It appears creamy/yellow in blood agar
111
What type of infection are A, C and G type antigen normally?
Tonsillitis and skin infections | Type A is normally strep. pyogenes.
112
What type of infection are B type antigen normally?
Sepsis and meningitis | Type B is normally strep Agalactiae
113
What areas of the body are sterile?
``` Blood Cerebrospinal fluid Pleural fluid Peritoneal cavity Joints Urinary tract Lower resp tract ```
114
What type of bacterias can use the oxidase test?
Non-lactose fermentors | Gram negative bacilli
115
What disease does m. tuberculosis form?
Tuberculosis
116
List some mycobacteria of medical importance
``` M. Tuberculosis M. Leprae M. Avum complex M. Kansasii M. Marinum M. Ulcerans ```
117
What are mycobacteria?
Aerobic, non-spore forming, non-motile bacillus, Slow growing Have resistance to gram stain (should be gram positive) , so need to be stained with acid and alcohol (Acid fast)
118
What is the issue with mycobacteria being slow growing?
It is difficult for antibiotics to target their division phase It is also hard to culture so harder to diagnose
119
What are some key cell wall components of mycobacteria?
Mycololic acids and liporabinomannan- make up a strong waxy cell wall that is hard for the immune system to target
120
Why are mycobacteria hard to diagnose and treat?
They are slow growing = take weeks to diagnose
121
What are Koch's postulates?
Bacteria should be found in all people with disease Bacteria should be isolated from the infected lesions in people with the disease A pure culture inoculated into a susceptible person should produce symptoms of the disease The same bacteria should be isolated from the potentially infected individual
122
How can you identify mycobacteria?
Ziehl-neelson stain (appears red/pink)
123
How can TB be diagnosed?
Culture growth (but takes weeks to get a result) Nucleic acid detection (Rapid diagnosis, highly sensitive) Tuberculin skin test (can analyse the amount of response to TB) Interferon gamma release assays= Uses antigens specific to TB to demonstrate exposure
124
How do mycobacteria cause infection?
- It is phagocytosed by macrophages but can withstand this, and escape into the cytosol - T cell stimulation - Granulomas arise in response to contain the mycobacteria - Central tissue may necrose to form a craveating granuloma - Granuloma tries to starve the mycobacteria - Excessive immune response = hypersensitivity reactions
125
What are the two types of leprosy?
Tuberculoid leprosy | Lepromatous leprosy
126
Why is TB infection so dangerous?
Associated with excessive tissue hypersensitivity and granuloma
127
What is tuberculoid leprosy?
- Associated with tissue hypersensitivity and granulomata - Tissue damage including nerve damage - Predominant Th1 biased CD4+ T cell responses
128
What is lepromatous leprosy?
- Lesions full of bacilli but little or poorly formed granulomata - Extensive skin lesions - Predominant Th2 biased CD4+ T cell responses
129
How is tuberculosis treated?
Standard therapy= Isoniazid, rifampicin, pyranzanamide, and ethambutol for 2 months, and isoniazid and rifampicin for a further 4 months If resistance develops= Fluroquinolones, prothionamide, injectable agents such as streptomycin
130
What are the different stages of tuberculosis?
Primary Latent Pulmonary TB spread beyond lungs
131
What is primary tuberculosis?
- Bacilli settle in apex and granuloma forms | - Bacilli taken in lymphatics to hilar lymph nodes
132
What is latent tuberculosis?
- Cell mediated immune response from T cells - Primary infection is contained but CMI persists - No clinical disease
133
What is pulmonary tuberculosis?
- Cell mediated immune response from T-cells - Necrosis in lesions - Caseous material coughed up leaving cavity - CMI and caseation in lesion results in cavity
134
Where does TB normally spread to beyond the lungs?
TB meningitis, Miliary TB, Pleural TB, Bone and Joint TB, Genitourinary TB
135
What is a virus?
An infectious, obligate intracellular parasite composing genetic material surrounded by a protein coat and/or a membrane
136
What are the stages of virus replication?
1. Attachment 2. Cell entry 3. Interaction with host cells 4. Replication 5. Assembly 6. Release
137
How can viruses cause disease?
- Direct destruction of host cells - Modification of host cell structure or function - Over-reactivity - Cell proliferation and cell immortilisation (Cancer) - Evasion of host defenses
138
What are the clinical features of poliovirus?
- It enters the body orally and then invades and replicates in the gut - Then travels to the bloodstream and targets the brain - Direct brain destruction - Can result in paralysis
139
What are the clinical features of rotavirus?
- Shortening and atrophy of the villi in the jejunum - Stripping of the microvilli - Malabsorptive state - Profuse diarrhoea
140
How is hepatitis B virus spread?
Blood or sexual contact
141
How does HPV cause cervical cell carcinoma?
- It infects the supra basal layer, where the virus becomes integrated into the host cell chromosome - Different proteins are expressed, preventing tumour suppressor genes
142
How can viruses be tested for?
PCR (Tests if viral genetic material is present) Serology (Is there immune memory) Histopathology (Is there any features of viral infection)
143
How do you get bovine TB?
M. Bovis from Cows
144
What is used to culture mycobacteria?
Löwenstein–Jensen medium
145
What are the three groups of worms?
Nematodes (Roundworms) Trematodes (Flatworms, flukes) Cestodes (Tapeworms)
146
What is the pre-patent period?
The interval between worm infection and the appearance of eggs in stool
147
What are protozoa?
Single-celled eukaryotic organisms with a definite nucleus
148
What are the four types of protozoa?
Mastigophora (Flagellates) Sarcodina (Amoebae) Apicomplexia (Sporozoans) Ciliophora (Ciliates)
149
List some common flagellate protozoa
- Giargia lambila - Trypanosoma spp. - Trichomonas Vaginalis
150
What infection is caused by trypanosoma spp. ?
Sleeping sickness - Chancre at site of bite - Fever, lethargy, myalgia, excessive weight loss, personality change, coma
151
What infection is caused by trichomonas vaginalis?
STD= Trichomoniasis
152
How do amoebae protozoa move?
Flowing cytoplasm and pseudopodia
153
What infection is caused by entamoeba histolytica?
Amoebiasis - Foecal oral transmission - Bloody diarrhoea - Liver abscess - Right upper quadrant pain - Rural botswana
154
What antibiotic is commonly used to treat protozoa infections?
Metronidazole
155
What infection is caused by toxoplasma gondii?
Toxoplasmosis - Commonly immunosuppressed patients in contact with feline faeces - Left sided weakness - Headaches and visual disturbances - Ring enhancing lesion on CT
156
What species of protozoa cause malaria infection?
- Plasmodia spp. | = P. Falciparum, P. Ovale, P. Vivax, P. Malariae
157
How is malaria infection transmitted?
Transmitted by the bite of the female anopheles mosquito
158
What is the developmental cycle of malaria within the vector?
- The female anopheles mosquito becomes infected after taking a blood meal containing infected gametocytes - After 7-20 days, the infective sporozoites have migrated into the insects salivary glands
159
What is the liver cycle of malaria within a human?
- Sporozoites are inoculated into a new human host - Taken up into the liver - They multiply inside hepatocytes as schizonts - After afew days, hepatocytes rupture releasing merozoites into the blood - P. Vivax and P. Ovale remain dormant in the liver
160
What is the blood cycle of malaria within a human?
- Merozoites are taken up into erythrocytes - The erythrocyte ruptures, releasing merozoites to infect further cells - Some immature trophozoites differentiate into gametocytes
161
List some clinical features of malaria
- Normal incubation period of 10-21 days - Fever - Chills and sweats - Headache - Myalgia - Fatigue - Hepatosplenomegaly - Nausea and vomitting - Diarrhoea - Anaemia= tiredness, dark urine, jaundice
162
Which plasmodia species(s) gives the most severe strain of malaria?
P. Falciparum
163
Which plasmodia species(s) give the most mild strain of malaria?
P. Vivax or P. Ovale
164
List some complications of malaria?
- Coma and confusion (Cerebral anaemia) - Adult resp distress syndrome - Anaemia - Jaundice - Hepatosplenomegaly - Renal failure - Shock
165
How does cerebral anaemia occur in malaria?
- Cytoadherance= Infected RBCs display specific membrane proteins to adhere to microvascular endothelium - They also adhere to other non-infective RBCs causing "Rosettes" - This blocks arteries
166
How is malaria diagnosed?
Thick and thin films - Thick= Tells if malaria is present and how severe - Thin= Identify specific species of plasmodia
167
How is malaria treated?
- Complicated malaria= IV artesunate - Uncomplicated= Oral riamet or oral quinine - P Vivax and P Ovale= Also give primaquine to prevent dormant stage
168
List some things that give immunity against malaria
- Sickle cell trait - Glucose-6-phosphate dehydrogenase deficiency - Thalessaemias
169
What are the key attributes of pathogens?
- Infectivity - Virulence - Invasiveness
170
What are the stages of pathogenesis?
Exposure, adhesion, invasion, infection, transmission
171
What are commensal microorganisms?
The resident flora and usually nonpathogenic
172
What are opportunistic infections?
Infections that only arise if immune status is altered
173
What is a zoonotic disease?
A disease that spreads between animals and people
174
List some humoral defenses against pathogens
- IgA= Blocks binding of pathogens - IgM= Agglutinates particles making them difficult to enter cells - Complement= Opsonisation and cell lysis - Antibodies= Neutralise toxins
175
List some examples of viruses that cause direct cell toxicity
Influenza virus to respiratory epithelium Varicella zoster virus to skin cells Yellow fever virus to liver cells HIV to CD4 T-cell
176
What are biofilms?
Produced by bacteria to help to stick together on a surface and help protect against microbes
177
What do bacterias adhesins do?
They help bacteria to bind to mucosal surfaces
178
What is the effect of TNF release in response to infection?
- Inflammatory response leading to some symptoms of infection (pyrexia, nausea, malaise)
179
Which inflammatory mediators cause vasodilation?
Prostaglandins Kinins Leukotrienes
180
Which inflammatory mediators cause increased vascular permeability?
Prostaglandins | Leukotrienes
181
List some beta lactam antibiotics
- Penicillins - B-lactamase inhibitors - Cephalosporins - Carbapenems - Monobactams - Glycopeptides
182
How do beta lactam antibiotics target bacteria?
- Inhibit cell wall synthesis by targeting peptidoglycan | - Therefore generally kill gram positive bacteria better than gram negative
183
What are antimicrobials?
Agents produced by micro-organisms that kill or inhibit the growth of other micro-organisms in high dilution
184
What are bacterosteric antibiotics?
Prevents the growth of bacteria, including those that inhibit protein synthesis, DNA replication or metabolism
185
What are bactericidal antibiotics?
Agents that kill the bacteria, kill more than 99% of bacteria in 18-24 hrs, generally inhibit cell wall synthesis
186
What is conc dependent killing?
Kills bacteria by having a high concentration above minimal inhibitory concentrations
187
What is time dependent killing?
Kills bacteria by sustained killing= how long does the conc stay above the minimal inhibitory conc
188
What is the minimal inhibitory conc?
The minimum concentration of antibiotic that is required to kill the bacteria
189
How do bacteria resist antibiotics?
- Target site mutation - Destroying or inactivation of antibiotics - Prevention of antibiotic entry - Pumping out the antibiotic from the cell
190
How does antibiotic resistant develop?
- Intrinsic natural resistance= The antibiotic doesn't work on that bacteria - Acquired resistance= Spontaneous gene mutation or horizontal gene transfer
191
What are some factors to consider when deciding if an antibiotic is safe?
- Intolerance, allergy - Side effects - Age - Renal and liver function - Pregnancy and breastfeeding - Drug interactions - Risk of C. Difficile
192
Name an antibiotic class that targets the bacterial ribosomal 50s subunit and one example
Macrolides (Includes clarythromycin and erythromycin)
193
Name an antibiotic class that targets the bacterial ribosomal 30s subunit and give one example
Tetracyclines (Tetracycline, doxycycline, lymecycline, minocycline) Aminoglycoside (Gentamicin)
194
Name an antibiotic class that works by targeting DNA gyrase and give an example
Quinolones (Ciprofloxacin, Levofloxacin, Moxifloxacin, Ofloxacin)
195
Name an antibiotic class that works by targeting RNA polymerase and give an example
Rifampin
196
Name an antibiotic that works by inhibiting folate synthesis
Trimethoprim | Sulfonamides
197
Name some antibiotics that inhibit cell wall synthesis
Glycopeptides e.g. Vancomycin Penicillins e.g. Amoxicillin, flucloxacillin Cephalosporins Carbapenems
198
Name some antibiotics which inhibit protein synthesis
Chloramphenicol Macrolides e.g. Erythromycin Tetracyclines Aminoglycosides e.g. Gentamycin
199
What would be the treatment of a lower UTI in a non-pregnant female?
3 days of oral nitrofurantoin | Could also use 3 days of oral trimethoprim
200
What would be the treatment of cellulitis?
Flucluxacillin +/- benzylpenicillin for 10-14 days
201
What would be the treatment of bacterial pneumonia?
Amoxicillin/ Co-amoxiclav for 5 days
202
What would be the treatment for strep. Aureus infections?
Flucoxacillin
203
What would be the treatment for group A,C,G strep tonsillitis?
Oral penicillin V, or IV benzylpenicillin
204
Which antibiotics can result in C. Difficile?
``` Generally antibiotics that begin with the letter C= Ciprofloxacin Clindamycin Cephalosporins Carbapenems Co-amoxiclav ```
205
What is the single most effective method of preventing cross infection?
Hand hygiene
206
What are the broadest spectrum beta-lactam antibiotics available?
Carbapenems
207
What are the 2 main approaches to viral diagnosis?
- Virus detection | - Serology
208
What are the methods of viral serology?
- CFT (Complement fixation test) - HA/HAI (Haemagglutination/ haemagglutination inhibtion) - ELISA (Enzyme linked immunosrbent assay) - RIA (Radioimmunoassay) - IF (Immunofluorescence)
209
Briefly explain the polymerase chain reaction
- Enzymes unzip chains of nucleic acid DNA/RNA and then make up complementary copies - Primer sequences are added - Cycles of heating and cooling - New chains are marked with fluorescent material - This is repeated many times
210
What are the pros and cons of PCR?
+ Sensitive and quick - So sensitive that it may give false positives - Only detects nucleic acid material complementary to primer sequence (need to know which virus you're looking for)
211
What is serology?
The study or detection of an antibody response in the serum (especially in IgG and IgM)
212
What are black swabs used for?
Bacteria detection
213
What are green swabs used for?
Viral detection
214
What is shingles?
- Varicella Zoster Virus - Causes shingles which can appear on various dermatomes - Usually seen at areas associated with tight clothing
215
What is a blue blood bottle used for?
Coagulation tests
216
What are yellow blood bottles used for?
U&E | Liver function tests
217
What are purple blood bottles used for?
Full blood cells
218
What are pink blood bottles used for?
Group and Save | Crossmatch
219
How can you detect if a virus is an acute infection?
There will be IgM, but not highly specific IgG antigens
220
How can you detect if a virus infection has been present chronically?
- Presence of both IgM and highly specific IgG antigens available
221
How is an ELISA test performed?
- Virus or bacterial antigen is absorbed to wells of a plate and washed - Patient serum added in dilutions - It is then washed - Enzyme substrate is then added - Washed - If positive, a colour change will occur
222
How long does a blood film take to get results?
Hours
223
How long does PCR take to get results?
A day
224
What does anti-streptolysin O titre detect?
Lancefield group A beta-haemolytic streptococci (Strep. Pyogenes) especially streptolysin O If positive, visible agglutination occurs
225
What can be tested using a CSF sample?
- Cell count - Gram stain for organisms - qPCR for virus and bacterial pathogens - Protein and glucose
226
How is HIV normally tested for?
COBAS Ag/Abs screen | If positive, repeat testing and if that is positive, report as positive
227
Give some signs and symptoms of infectious mononucleosis?
- Central= Fatigue, malaise, loss of appetite, headache - Photophobia - Tonsils= Reddening, swelling and white patches - Resp= Cough - Lymph nodes swelling - Chills and fever - Splenomegaly
228
``` Chains of purple cocci are seen on a gram film. They don't grow near the optochin disc These are probably.. A) Streptococcus pneumoniae B) Staphylococcus epidermidis C) Viridans Streptococci D) S. pyogenes E) Neisseria meningitidis ```
Correct answer=A
229
``` A pink colony is picked off this MacConkey plate and is found to contain pink staining bacilli with Gram's staining. Which organism is most likely? A) Shigella sonnei B) Listeria monocytogenes C) Neisseria meningitidis D) Eschericia coli E) Streptococcus pyogenes ```
Correct answer= D
230
``` Which of the following is Haemophilus influenzae NOT an important cause of? A) meningitis in pre-school children B) Otitis media C) Pharyngitis D) Gastroenteritis E) Exacerbations of COPD ```
Correct answer= D
231
Which of these is NOT a means by which viruses cause disease? A) direct destruction of host cells B) cell proliferation and cell immortalisation C) inducing immune system mediated damage D) Endotoxin production E) modification of host cell structure or function
Correct answer= D
232
The HIV envelope contains A) RNA + capsid + DNA polymerase B) DNA + capsid + RNA reverse transcriptase C) DNA + p24 + RNA polymerase D) RNA + capsid + RNA reverse transcriptase E) RNA + gp120 + RNA polymerase
Correct answer = D
233
List some protozoa
Giardia Lamblia Toxoplasma Falciparum malaria
234
Which micro-organisms resist destaining by acid and alcohol?
Mycobacteria
235
Which micro-organisms have a cell wall containing lipoarabinomannan?
Mycobacteria
236
Which micro-organisms divide every 30-60 minutes?
Bacteria
237
Which micro-organisms usually withstand phagolysomal killing?
Mycobacteria
238
Which micro-organisms can cause meningitis?
Bacteria
239
How is antimicrobial resistance spread?
Plasmid mediated gene transfer
240
A 21 year old complains of myalgia, sore throat and tiredness. He is febrile and has an enlarged spleen. On examination, he has purulent tonsils. What is it likely to be?
Glandular fever caused by EBV
241
What causes pneumocystis pneumonia in HIV?
P. jirovecci = an opportunistic fungal infection
242
What groups of people are most at risk of HIV?
Gay and bisexual men, sex workers, people who inject drugs, black-African men and women, Uncircumised men
243
How can HIV be transmitted?
Sexual= World-wide, sexual intercourse accounts for the vast majority of infections Vertical = Mother to child in utero or through breast feeding Blood
244
List some HIV preventative measures
``` Antiretroviral treatment (U=U) PreP Circumcision PEP STI control Vaccines Microbicides HIV diagnosis / partner notification Behavioural / condom use Screen blood products / needle exchange ```
245
Explain U=U
If viral load is treated and lowered meaning that the antiretroviral load is low, then it can’t be transmitted Undetectable= Untransmittable
246
What is pre-exposure prophylaxes?
Taking HIV medication before sex to prevent transmission | About an 86% Risk reduction
247
What is post-exposure phopholyaxes?
Antiretroviral therapy after exposure to HIV (must be started within 72 hrs of exposure)
248
List some benefits of knowing HIV status?
``` Access to appropriate treatment and care Reduction in morbidity and mortality Reduction of vertical transmission Reduction of sexual transmission Public health Cost-effective ```
249
What are the risk factors of HIV?
Sexual contact with people from high prevalence groups Multiple sexual partners Sexual assault Vertical transmission
250
What are the components of a viron?
- Lipid envelope - Nucleic acid - Protein capsid - Viron associated polymerase - Spike projections
251
What are the steps if HIV replication?
``` Attachment Entry Uncoating Reverse transcription (error prone so genomic variability) Genome integration Transcription of viral RNA Splicing of mRNA and translation into proteins Assembly of new virions Budding ```
252
What are the types of HIV?
M (main), O (outlying) and N (new) groups. | Main group separated into clades A-D, F-H, J-K.
253
Where is clade B HIV most predominant?
Europe and USA
254
Where is clade A HIV most predominant?
West and central Africa
255
Where is clade C HIV most predominant?
Southern Africa
256
Where is HIV-2 found?
Mainly West Africa
257
Why does HIV have reverse transcriptase enzyme?
To allow viral RNA to be transcribed into DNA and thence incorporated into host cell genome
258
Why is there considerable genetic variation in HIV?
Reverse transcriptase enzyme is highly error-prone due to high rate of viral turnover
259
What cell type does HIV target?
CD4 T helper cells
260
What does gp120 glycoprotein do on HIV?
- Allows HIV to bind to CD4 receptors | - Allows for HIV entry into cells
261
What does HIV's integrase enzyme do?
Integrate the double stranded HIV viral DNA into the host cells DNA
262
Why does CD4 count lower in HIV?
Activated CD4 cells will apoptose via Fas ligand upregulation
263
Why are HIV vaccines difficult to make?
There is ongoing virus replication and mutation | Ethical constraints
264
How does HIV develop drug resistance?
Non-adherance | Drug-Drug interactions
265
What is aids?
Acquired immune deficiency syndrome | - Defined as a CD4 count of less than 200 cells per mm3
266
What is the clinical presentation of acute primary infection of HIV?
- Transient immunosuppression and fall in CD4 count followed by a gradual rise - Acute rise in viral load - Transient illness 2-6 weeks after exposure with abrupt onset of non specific symptoms (Fever, malaise, pharyngitis, weight loss, rash)
267
What is the clinical presentation of the asymptomatic phase of HIV?
- Progressive loss of CD4 T cells resulting in poor immunity | - Can have generalised lymphadenopathy
268
What is the clinical presentation of the symptomatic phase of HIV?
- Rise in viral load and fall in CD4 count - Fever, night sweats, diarrhoea, weight loss - Minor opportunistic infections: Oral candida, herpes zoster, PID - Resp condition= Dry cough - Known as AIDS-related complex (ARC)
269
How long does it normally take for HIV to develop into AIDS?
8 years
270
List some AIDS defining conditions
- Infections= Candidiasis oesophageal/ lung, TB, Persistant herpes simplex, Pneumocystitis jiroveci, bacterial pneumonia - Neoplasms= Kaposi's carcinoma, invasive cervical carcinoma - Toxoplasmosis
271
What are the two methods of testing for HIV?
CD4 T cell count/μl and HIV viral load (RNA copies/ml)
272
When should patients be tested for HIV?
- High protein but low albumin on bloods - Non-specific symptoms - Recurrent shingles and candidiasis - If there is a sharp drop in O2 stats after walking (Pneumocystitis pneumonia)
273
When would IgG antibody p24 be used to test for HIV?
- If it is early on = it is frequently lost as the disease progresses
274
When are genome detection assays used to test for HIV?
Used to test for HIV in the babies of HIV positive mothers
275
What are the possible treatments for HIV?
``` HAART NRTI NNRTI PI Fusion inhibitors Integrase inhibitors ```
276
What is HAART?
Highly active antiretroviral therapy - Aims to reduce viral load and increase CD4 count - Uses 3 drugs to minimise replication and cross resistance
277
How do nucleoside reverse transcriptase inhibitors (NRTIs) help to treat HIV, and give one example
Examples: Abacavir, Didanosine, Emtricitabine | They inhibit the synthesis of DNA by reverse transcription and act as DNA chain terminators
278
How do non-nucleoside reverse transcriptase inhibitors (NNRTIs) help to treat HIV, and give one example
Examples: Efavirenz, Etravirine, Nevirapine | Bind directly to, and inhibit reverse transcriptase
279
How do protease inhibitors help to treat HIV and give one example
Examples: Atazanavir, Darunavir, Indinavir | Act competitively on HIV enzyme involved in production of functional viral proteins and enzymes
280
How do fusion inhibitors help to treat HIV and give one example
Example: Enfuvirtide | Inhibits fusion of HIV with target cells
281
How do integrase inhibitors help to treat HIV and give one example
Example: Raltegravir | Prevents the insertion of HIV DNA into the human genome
282
What are the sanctuary sites for HIV?
``` Genital tract Central nervous system GI system Bone marrow Macrophages & Microglia ```
283
How can children of HIV infected mothers become infected with HIV?
In-utero Intra-partum Via breast milk
284
What are the risk factors for mother-to-child transmission of HIV?
- High maternal plasma viral load - Viral strain (HIV2 is rarely passed mother to child) - Breast feeding
285
What are the clinical features of varicella zoster virus infection?
Chickenpox - Brief fever, headache and malaise - A rash, predominantly on the face, scalp and trunk - Macules, then papules, then vesicles
286
What are the clinical features of herpes zoster virus inefction?
Shingles - Remains in dorsal root ganglia - Pain and tingling in a dermatomal distribution - Papules and vesicles in same dermatome- commonly lower thoracic and opthalmic division of trigeminal
287
A 6 year old patient is seen with macules on the face and trunk. He has been feeling unwell with a headache and fatigue. What is it likely to be?
Chickenpox | varicella zoster virus
288
A 68 year old man is in clinic complaining of a rash along his back. It is papules and vesicles and they are running in a line. What is it likely to be?
Shingles | Herpes zoster virus
289
How is infective endocarditis by strep. viridans treated?
IV benzylpenicillin for 4-6 weeks +/- synergistic gentamicin for the first 2 weeks
290
How is infective endocarditis by enterococci treated?
IV amoxicillin and gentamicin for 4-6 weeks
291
List some lancefield group A conditions?
Pharyngitis, cellulitis, erysipelas, necrotising fascitis, septicaemia, rheumatic fever, Acute glomerulonephritis, Scarlet fever
292
List some lancefield group B conditions?
Neonatal meningitis and septicaemia
293
List a lancefield group C condition?
Pharyngitis, cellulitis
294
List a lancefield group D bacteria
Enterococci
295
List a lancefield group G condition?
Cellulitis
296
How can you differentiate beta-haemolytic bacteria?
Lancefield grouping
297
One way bacteria can be classified as gram positive and gram negative. What do these terms mean?
Gram positive bacteria have cell walls composed of thick layers of peptidoglycan. Gram positive cells stain purple when subjected to a Gram stain procedure. Gram negative bacteria have cell walls with a thin layer of peptidoglycan
298
A mother brings her 18 month child to General Practice complaining of having seen small white “threads” in the nappy. What is the likely cause and the most appropriate treatment?
- Threadworms | - Mebendazole
299
What is the commonest condition associated with Mycobacteria? What term is used to describe these bacteria which is relevant to detecting them in the labs?
- Tuberculosis | - Acid fast= Resistant to standard staining and require specific tests
300
What are the five properties of a virus?
- Grow only inside living cells - Contain either RNA OR DNA - No cell wall, but have an out protein coat - Carry enzymes that function inside the cell - Protein receptors on surface to allow attachment to host cell
301
What viral vaccine has been introduced to the UK programmme and what cancer is it designed to prevent?
- Human papilloma virus | - Cervical cancer
302
What is the commonest causative organism in fungal nail infection?
Trichophyton species
303
A patient presents with fever and recent travel overseas to Africa. What protozoal illness should be top of your differential diagnosis and what is the key diagnostic test?
- Malaria | - Thick and thin blood film
304
Summarise what an antibiotic is and how it works
Antibiotics are molecules that work by binding a target site on a bacteria
305
Give four possible clinical situations that might indicate the need of a HIV test
- Prolonged episodes of herpes simplex - Persistent frequently recurrent candidiasis - Recurrent infections - Oral candida - Indicators of immune dysfunction - Odd looking mouth lesions - New onset abnormal skin lesions (Kaposi’s sarcoma)

Phase 2a (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions