Infection Flashcards
(132 cards)
1
Q
What is an antimicrobial?
A
A chemical agent that inhibits the growth of, or destroys, microorganisms.
2
Q
What does colonisation refer to?
A
The presence, growth and multiplication of an organism without observable clinical symptoms or immune reaction.
3
Q
Define endemic.
A
The normal background incidence of a disease in a population.
4
Q
What is an epidemic?
A
A sudden increase in the incidence of a disease affecting many people in a short time frame in a specific location.
5
Q
What characterizes a pandemic?
A
A disease that spreads rapidly and widely across multiple countries or continents.
6
Q
What is flora in the context of microbiology?
A
Microorganisms that inhabit a body region without causing infection.
7
Q
What is a healthcare-acquired infection?
A
An infection acquired by an individual in a healthcare facility.
8
Q
What is the definition of infection?
A
Invasion of a pathogenic microorganism causing symptoms.
9
Q
What are microorganisms?
A
Includes bacteria, viruses, fungi, and parasites; many do not harm humans.
10
Q
What is an opportunistic infection?
A
An infection caused by a microorganism that normally would not harm a healthy individual.
11
Q
Define pathogen.
A
A microorganism that causes disease.
12
Q
What is a superinfection?
A
An infection that arises when antimicrobials reduce the body’s normal flora, allowing overgrowth of other microorganisms.
13
Q
What is a vaccine?
A
A biological agent that provides immunity to a disease by stimulating antibody production.
14
Q
What are the factors influencing infection by a pathogen?
A
- Mechanism of action
- Infectivity
- Pathogenicity
- Virulence
- Immunogenicity
- Toxigenicity
15
Q
What is infectivity?
A
The ability of the pathogen to invade and multiply in the individual.
16
Q
Define pathogenicity.
A
The ability of an agent to produce disease.
17
Q
What does virulence measure?
A
The potency of a pathogen in terms of the number of microorganisms or micrograms of toxin required to kill a host.
18
Q
What is immunogenicity?
A
The ability of pathogens to induce an immune response.
19
Q
What is toxigenicity?
A
A factor important in determining a pathogen’s virulence, such as toxin production.
20
Q
Name the main routes of entry for pathogens.
A
- Direct contact
- Inhalation
- Ingestion
- Penetration of the skin
21
Q
What are the five main classes of microorganisms?
A
- Bacteria
- Fungi
- Parasites
- Protozoa
- Algae
22
Q
What distinguishes viruses from other infectious agents?
A
Viruses are not cellular and therefore are not classified as organisms.
23
Q
What is an example of a common intestinal protozoan?
A
Giardia intestinalis, which causes diarrhoea and abdominal pain.
24
Q
True or False: The majority of deaths due to infectious diseases in Australia are caused by viruses.
A
False; 72% were caused by bacteria.
25
True or False: Smallpox is the only infectious disease that has been eradicated worldwide by vaccination.
True
26
What significant effect did sanitary living conditions have on infectious disease mortality rates?
Greatly reduced the mortality rate from infectious diseases.
27
What are viruses classified as?
Infectious agents that are not cellular and therefore are technically not organisms.
28
What rare infectious proteins can cause disease?
Prions.
29
Which intestinal protozoan is commonly found in contaminated drinking water and causes diarrhoea?
Giardia intestinalis.
30
What is the size range of viruses?
20–30 nm.
31
Name two examples of viral diseases.
* Measles
* Influenza (flu)
32
What are the three main bacterial shapes?
* Cocci (spherical)
* Bacilli (rod-shaped)
* Spirochaetes (spiral-shaped)
33
What is the purpose of the gram stain test?
To differentiate between gram-positive and gram-negative bacteria.
34
What color do gram-positive bacteria stain?
Purple.
35
What distinguishes gram-negative bacteria from gram-positive bacteria?
Gram-negative bacteria have a thin peptidoglycan layer and an additional outer membrane.
36
What are exotoxins?
Proteins released during bacterial growth with specific effects on host cells.
37
What are endotoxins formed from?
Lipopolysaccharides in the outer membrane of certain gram-negative bacteria.
38
What condition is characterized by the presence of microorganisms in the blood?
Septicaemia.
39
What is the main difference between septicaemia and bacteraemia?
Bacteraemia refers specifically to the presence of bacteria in the blood.
40
What is the structure of a virus composed of?
Nucleic acid protected by a protein layer called a capsid.
41
What type of nucleic acid can viruses have?
* RNA (ribonucleic acid)
* DNA (deoxyribonucleic acid)
42
What is the productive or lytic cycle of a virus?
A cycle where the virus replicates its genetic material and produces new virions, often destroying the host cell.
43
What is the term for when a virus remains dormant in a host cell?
Latency phase.
44
What can trigger a virus to exit latency and become active?
Stress, immunosuppression, hormonal changes, or disease.
45
What harmful effect can a virus have on host cells?
Cessation of DNA, RNA, and protein production.
46
What is an example of a virus that can transform host cells into cancerous cells?
Human papillomavirus.
47
What are the two categories of virion effects on host cells?
* Direct damage through cellular destruction
* Alteration of cellular functions
48
Name one disease caused by a DNA virus.
* Hepatitis B virus
49
What is the typical size range of bacteria?
0.8–15 microg.
50
What is the role of the complement system in inflammation?
Involved in bacterial destruction.
51
True or False: Exotoxins are immunogenic and can elicit the production of antitoxins.
True.
52
Fill in the blank: The presence of an endotoxin in gram-negative bacteria increases _______.
virulence.
53
What can excessive capillary permeability caused by endotoxins lead to?
Hypotension and septic shock.
54
What is the most common cause of infections in hospitals?
Bacteria.
55
What is the term for the release of vasoactive peptides and cytokines due to endotoxins?
Vasodilation.
56
What family of viruses includes SARS and SARS-CoV-2 (COVID-19)?
Coronaviridae
57
Which virus family is associated with Ebola and Marburg haemorrhagic fever?
Filoviridae
58
Name two viruses from the Flaviviridae family.
* Yellow fever
* Dengue
59
Which viruses are included in the Orthomyxoviridae family?
* Influenza A
* Influenza B
* Influenza C
60
What type of viruses does the Paramyxoviridae family include?
* Parainfluenza viruses
* Mumps virus
* Measles virus
* Respiratory syncytial virus
* Metapneumovirus
* Nipah virus
61
List some viruses from the Picornaviridae family.
* Polio viruses
* Coxsackie A viruses
* Coxsackie B viruses
* Echoviruses
* Enteroviruses 68–71
* Enterovirus 72 (hepatitis A virus)
* Rhinoviruses
62
What is the primary type of virus in the Reoviridae family?
Rotavirus
63
Which viruses are classified under Retroviridae?
* Human immunodeficiency viruses (HIV-1 and HIV-2)
* Human T-lymphotrophic viruses (HTLV-1 and HTLV-2)
64
Which virus is associated with the Rhabdoviridae family?
Rabies virus
65
What viruses belong to the Togaviridae family?
* Eastern equine encephalitis virus
* Western equine encephalitis virus
* Venezuela equine encephalitis virus
* Rubella virus
66
What are fungi?
Relatively large eukaryotic microorganisms that grow as single-celled yeasts or multicelled moulds
67
What is the structural composition of fungal cell walls?
Rigid and multilayered, composed of polysaccharides different from bacterial peptidoglycans
68
What term describes fungi that can exist in both yeast and mould forms?
Dimorphic fungi
69
What are mycoses?
Diseases caused by fungi
70
What type of mycoses occurs on or near skin or mucous membranes?
Superficial mycoses
71
What are dermatophytes?
Fungi that invade the skin, hair, or nails
72
Fill in the blank: The diseases produced by dermatophytes are called _______.
tineas
73
What is the primary mechanism by which fungi adapt to host environments?
By digesting keratin and suppressing host immune defences
74
How do deep fungal infections typically enter the body?
Through inhalation or open wounds
75
What is Candida albicans?
A fungus usually found in the mouth, gastrointestinal tract, and vagina of healthy individuals
76
What is the effect of antibiotic use on Candida albicans?
It can lead to rapid proliferation and overgrowth
77
What are the two requirements for diagnosing pathogenic microorganisms?
* Detailed clinical history and physical examination
* Laboratory evidence of the infectious agent
78
How are bacteria typically detected in the laboratory?
Using cultures from body fluids and specimens
79
What is the difference between bactericidal and bacteriostatic antibiotics?
* Bactericidal: directly kill bacteria
* Bacteriostatic: neutralise further bacterial growth
80
What are monoclonal antibodies (Mabs)?
Identical copies of an antibody that bind to the same antigen
81
List the four main classes of antibiotics based on their mechanism of action.
* Break down the cell wall
* Interfere with nucleic acid activity
* Stop protein production
* Interfere with cellular metabolic activities
82
True or False: Fungi can resist the action of bacterial cell wall inhibitors.
True
83
What are the stages of infectious illness?
* Infection
* Incubation
* Symptoms
* Shedding of the microorganism
84
What is a hallmark symptom of most infectious diseases?
Fever
85
What factors are associated with pathogens causing infections?
* Ability to produce toxins
* Ability to evade the immune response
* Ability to adapt to host environments
86
What does antigenic drift refer to?
Changes in appearance by altering surface antigens over time
87
Fill in the blank: The process of gene switching in some pathogens allows them to change surface antigens, similar to _______.
antigenic variation
88
What is the significance of the immune response in infectious diseases?
Majority of clinical symptoms result from host’s inflammatory and immune responses
89
What are monoclonal antibodies (Mabs)?
Identical copies of an antibody that bind to the same antigen or epitope.
90
How do monoclonal antibodies work in cancer treatment?
They bind to antigens on cancer cells, stimulating the body’s natural killer cells and promoting apoptosis.
91
What role do T cells play in cancer treatment using Mabs?
Stimulating T cell function is important in the checkpoints within the normal cell cycle.
92
What are antiviral agents developed to treat?
Viruses such as coronaviruses, influenza, HIV, hepatitis, and herpesvirus.
93
How do most antiviral drugs suppress viral replication?
By mimicking a section of viral DNA or blocking enzymes required for replication.
94
What is the mechanism of action for aciclovir?
It binds with an enzyme that combines with viral DNA to block viral replication.
95
Why are antifungal drugs potentially toxic?
Because fungal cell composition is similar to human cells.
96
What is the purpose of vaccination?
To induce long-lasting protective immune responses without causing disease.
97
What happens during the primary immune response?
Activated B cells produce antibodies against the pathogen and memory cells are formed.
98
What is the effect of booster injections in vaccination?
They enhance secondary immune responses, resulting in more memory cells and sustained antibody levels.
99
What is herd immunity?
A certain percentage of the population must be immunised to protect the total population.
100
What are attenuated viruses?
Weakened viruses that do not cause disease when administered.
101
What are the two types of poliovirus vaccines?
* Sabin vaccine (attenuated)
* Salk vaccine (inactivated)
102
What is the recommended immunisation schedule for infants in Australia?
Includes Diphtheria, tetanus, whooping cough, hepatitis B, polio, and Hib at 2, 4, and 6 months.
103
What is a toxoid vaccine?
Purified toxins that have been chemically detoxified but retain immunogenicity.
104
What is the difference between live attenuated vaccines and inactivated vaccines?
Live attenuated vaccines can cause mild infections, while inactivated vaccines cannot.
105
What is a conjugated vaccine?
Contains capsular polysaccharides linked to carrier proteins to increase immunogenicity.
106
What is the issue with vaccine compliance?
A certain percentage of the population must be immunised to prevent outbreaks.
107
What is the role of macrophages in mRNA vaccines?
They take up mRNA and translate it into viral spike proteins to generate an immune response.
108
What is the significance of the spike protein in COVID-19 mRNA vaccines?
It is the target for the immune response generated by the vaccine.
109
Fill in the blank: The first natural exposure to a microorganism produces a _______.
primary immune response.
110
True or False: Vaccination can completely eliminate the need for immunisation.
False.
111
What is the difference between the measles vaccine and the pertussis vaccine in terms of formulation?
Measles vaccine is typically live attenuated, while pertussis vaccine has shifted to an acellular formulation.
112
Define the term antimicrobial and explain how antimicrobials work.
Antimicrobials are agents that kill or inhibit the growth of microorganisms. They work by targeting specific features of the microorganism, such as cell wall synthesis, protein synthesis, or DNA replication.
113
What is a vaccine?
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease.
114
List some common infections in children and adults in Australia and New Zealand.
* Common cold
* Urinary tract infection (UTI)
* Helicobacter pylori infection
* COVID-19
* Staphylococcus aureus infections
115
What is the severity range of common infections?
The severity of most infections ranges from mild irritation to serious bed-bound conditions that take days or weeks to overcome.
116
True or False: The common cold is usually a bacterial infection.
False
117
What is the primary cause of the common cold?
The common cold is primarily caused by viral infections, including rhinovirus and coronavirus.
118
How are common cold infections typically diagnosed?
Diagnosis is made using clinical signs and symptoms, rather than by identification of the pathogen.
119
What is Helicobacter pylori?
Helicobacter pylori is a gram-negative rod bacterium associated with chronic gastritis and peptic ulcers.
120
At what age is H. pylori colonization most common in developing countries?
In developing countries, most of the population is colonized by H. pylori before the age of 10 years.
121
What is a common treatment for H. pylori infection?
Pharmacological treatment typically involves a proton pump inhibitor and antibiotics.
122
What is a urinary tract infection (UTI)?
A urinary tract infection occurs when there are significant numbers of bacteria in the urinary tract causing lower and upper tract infections.
123
Fill in the blank: The gram-negative anaerobe _______ accounts for the majority of uncomplicated community-based urinary tract infections.
Escherichia coli
124
What are some signs and symptoms of a urinary tract infection?
* Dysuria
* Fever
* Urinary urgency and frequency
* Haematuria
* Smelly, cloudy urine
125
What are standard precautions in infection control?
* Appropriate hand hygiene
* Use of gloves in invasive procedures
* Use of aprons and facial protection
* Safe handling of sharps
* Regular cleaning of surfaces and equipment
126
What is the estimated number of healthcare-acquired infections (HAIs) in Australia per year?
Approximately 165,000 HAIs per year.
127
What are the four priority HAIs in Australian hospitals?
* Surgical site infection (SSI)
* Staphylococcus aureus blood stream infection (SABSI)
* Clostridioides difficile infection (CDI)
* Central line acquired blood stream infection (CLABSI)
128
What is methicillin-resistant Staphylococcus aureus (MRSA)?
MRSA is a strain of Staphylococcus aureus that is resistant to methicillin and other antibiotics.
129
What is the primary cause of Clostridioides difficile infections?
C. difficile infections often occur following broad-spectrum antibiotic therapy that disrupts normal gut flora.
130
What are some mechanisms by which microbial pathogens develop resistance?
* Inactivation of the drug
* Alteration of bacterial membrane
* Alteration of the target molecule
* Reduced uptake or active efflux of the antibiotic
131
True or False: Overuse of antibiotics contributes to the development of antibiotic resistance.
True
132
List strategies to reduce the development of antimicrobial resistance.
* Better surveillance of antimicrobial resistance
* Reduction in the use of antimicrobials for animal husbandry
* Increased attention to infection control and vaccination
* Regulations and education for rational use of antimicrobials
