Module C: Infectious Disease and Their Control Flashcards
What condition does Bacillus anthracis cause?
Anthrax
What pathogen causes Tuberculosis?
M. tuberculosis
What pathogen causes Cholera?
Vibrio cholera
What four things does Robert Koch postulate to prove a link between a particular microbe and a disease?
- The suspected germ must be present in every case of the disease
- The germ must be isolated and grown in pure culture
- The cultured germ must cause the disease when it is inoculated into a healthy, susceptible experimental host
- The same germ must be reisolated from the diseased experimental host
What is an endemic?
An endemic disease is always present in given population. Must be a permanent reservoir (human or otherwise)
What is an epidemic?
A sudden rapid rise in the incidence of a disease in a particular population/area
What is a pandemic?
A global epidemic
What is an outbreak?
A relatively high number of infections are observed where no cases or sporadic cases have occurred in the past.
What is Bordetella pertussis?
A bacteria that lodges at the base of cilia within the lungs and causes a loss of cilia
What are viral infections of the gut covered in this course?
Rotavirus and norovirus
Are the lungs more likely to be infected via viruses or bacteria?
Viral infections extremely more common
What are bacteria infections of the gut covered in this course?
E. Coli
Salmonella
Cholera
Eukaryote (Giardia)
What is vibrio cholera?
One of the most widespread and serious bacterial GI pathogens. IT disrupts intracellular signalling and is transferred via faeces.
What does Chlamydia result in?
Pelvic inflammatory disease and infertility
What does syphilis result in?
Neurological effects
Host influence of disease outcomes?
Age Gender Genotype Behaviour (hygiene) Previous exposure to the pathogen Health status (immunocompromised?)
Three domains of life?
Bacteria
Archaea
Eukarya
Characteristics of a prokaryote?
No nucleus
Also (generally) no membrane-bound organelles
What domains of life are prokaryotes?
Archaea and bacteria
What are biofims?
Biofilms are a collective of one or more types of micro-organisms that can grow on many different surfaces.
Problem with microscopy and bacteria?
You can only check for shape since bacteria are often colourless. Need a phase contrast to see and usually require staining.
What is Gram Stain dependent on?
Differences in the make-up of the cell wall
What type of bacteria can form endospores?
Gram +ve bacilli
When do spores occur in bacteria?
When nutrients required by cell are depleted
What are exotoxins?
Secreted molecules that cause harm to host. Disrupt or inhibit cellular function.
What bacteria release endotoxins?
Predominately Gram -ve bacteria do, but some components of Gram +ve’s cell wall can give similar responses.
found in all Gram -ves
What do endotoxins do?
Released upon bacterial cell death. Bind to macrophages. They are powerful activators of acute-phase and inflammatory immune responses.
What two groups are virulence factors in?
Factors that promote colonisation
Factors that damage the host
What are examples of virulence factors that promote colonisation?
Allow access to ideal niche
Resist physical forces that may remove pathogen
Evade immune system
Increased access to nutrients
What are the two main virulence factors that damage the host?
Exotoxins and endotoxins
Why aren’t viruses considered living organisms?
They consist only of DNA or RNA and protein
Are incapable of independent reproduction
Smaller than any cell and have no cell membrane
No ribosomes, mitochondria and very few enzymes
Three types of virus structures?
Icosahedral
Helical
Complex
Six steps of the viral life-cycle?
Attachment Penetration Uncoating Replication Assembly Maturation and release
What is tropism?
The turning of all or part of an organism in a particular direction in response to an external stimulus (i.e. virus)
What is a capsid?
A capsid is the protein shell of a virus.
What part of the virus attaches to the host?
The viral attachment protein
Where do viruses replicate?
In the nucleus
Two ways cells are damaged via virus replication?
The cell can rupture during virus release, or
The cell commits suicide in response (apotheosis)
What does Functio Laesa mean?
Medical term for loss of function
What is the medical term for pain?
Dolor
What is the medical term for redness on skin?
Rubor
What is the medical term for localised heat?
Calor
What is the medical term for swelling?
Tumour
Why do our bodies go into fever?
Higher temperature unstable for viruses
What is the medical term for presence of virus in the blood?
Viraemia
What is adenovirus?
A double DNA respiratory virus. Causes tumours
What is papillomavirus?
A double DNA virus; symptoms include warts/cervical cancer
What is polyomavirus
A tumour enduring double DNA virus
What is herpesvirus?
A double DNA virus, with herpes as disease
What is poxvirus?
A double DNA virus; gives smallpox/cowpox
Out of adenovirus, papillomavirus, polyomavirus, herpesvirus and poxvirus, which contain an envelope?
Herpes and poxs
What is parvovirus?
A single stranded DNA virus that gives a mild rash
What is reovirus?
A double stranded RNA virus that gives rotavirus (diarrhoea) and the Colorado tick fever virus
What percentage of people have type 1 HIV in their lives?
4/5 people
What is picornavirus?
A single stranded RNA (mRNA) virus that gives the common cold (rhinovirus), hepatitis A and poliovirus
What is coronavirus?
A single stranded RNA that gives SARS
What is SARS?
Sever Acute Respiratory Syndrome
What is flavivirus?
A single stranded RNA virus that gives yellow fever, west nile virus and hepatitis C
What is togavirus?
A single stranded RNA virus that gives Rubella virus and equine encephalitis virus
What is filovirus?
A single stranded RNA virus that serves as a template for mRNA synthesis - associated with the ebola virus
What is orthomyxovirus?
A single stranded RNA virus that serves as a template for mRNA synthesis - associated with influenza
What is paramyxovirus?
A single stranded RNA virus that serves as a template for mRNA synthesis - associated with the measles virus
What is rhabdovirus?
A single stranded RNA virus that serves as a template for mRNA synthesis - associated with rabies
What is retrovirus?
A single stranded RNA virus that serves as a template for DNA synthesis - associated with human immunodeciency virus
Out of all the STI viruses, which is on the rise in Australia?
HIV
Weight of bacteria in and around the human body? What percentage is gut?
1.25kg around the body, 1kg is in gut
Where is the most stable site for gut flora? How many days can it last?
The gut - up to 300 days
Resident bacteria of skin?
Mainly gram positive cocci
Staphylococcus epidermidis and staphylococcus aureus
Where do bacteria reside in the mouth, nose and vagina?
In the mucoid layer
Microbes found on teeth and gums?
Streptococci, Bacteroides, Fusobacterium, actinomyces
What do bacteria on teeth do?
They calcify to form biofilm (calculus plaque)
What bacteria reside in the GI tract?
Most Gram negative bacteria
What is the rule of thumb for microbe count in the GI tract?
The more you move toward the colon, the more diversity and density
What is the reflux bacteria?
Helicobacter pylori
Benefits of microflora in GI tract?
Beneficial metabolites (waste products)
Vitamin production (like b12 and K group)
Produces short-chain fatty acids - triggers for satiety and epithelial preservation
What is the usual culprit for an UTI?
Escherichia coli
UTI stats in males vs females?
50% of women will have >1 UTI; 12-15% in men
What is MRSA?
Methicillin-resistant Staph. aureus - a skin condition that’s difficult to treat
What is the correct term for thrush?
Dandida albicans
Why does thrush occur?
It’s a typical resident, but usually antibiotics or hormone induced pH changes promote a landscape it can thrive in.
What is Clostridium difficile?
An antiobiotic-associated diarrgoea. Causes severe symptoms and kills the host via dehydration
What are MRSA, UTI, thrust and Clostridium difficile all examples of?
An opportunistic infection
Why do opportunistic infections occur?
Colonisation of different body site
Inadequate immune response
Asymptomatic carrier
Overgrowth of resident microbe
What is VRSA?
Vancomycin Resistant S. aureus
What is clostridium difficile?
A Gram positive bacilli bacteria; spore forming
Where is clostridium difficile found?
Faeces of neonates and infants until weaning
How does clostridium difficile appear in adults?
Induced by distrubance of gut flora (antibiotics, cytotoxic drugs etc)
What disease does clostridium difficile give?
Diarrhoea
Via what process does clostridium difficle damage the target cell?
Exotocins
What medicine is administered for clostridium difficile?
For mild symptoms; metronidazole,
For severe; vancomycin
Surgery may be needed for colon repair
Major causative organism of UTIs?
E. Coli
What disease can UTI lead to?
Pyelonephritis
How is UTI diagnoses?
Dipstick test: for metabolites and pus in urine. If neither are present, unlikely UTI
Virulence factors of paramyxoviridae?
Gram negative RNA genome
Major problem with RSV? (respiratory syncytial virus)
No specific treatment or vaccine
How does rotavirus cause damage?
IT replicates at the tip of microvilli - followed by a lytic cycle (cell death)
What is the causative agent of measles?
Morbillivirus
What are haemolysins?
Lipids and proteins that cause lysis of RBC’s
Key virulence factor of morbillivirus?
It has haemolysin proteins that clump RBCs
What does YOPI stand for? What is it referred to for?
Susceptible hosts: Young Old Pregnant Immunocompromised
Infection control for doctor talking to patient in patient bed? (From lecture)
Wash hands before AND after
Gloves/masks in certain scenarios
Make sure equipment is sterilised (and equipment must be constantly up-kept) and clean sheets
Infection control for someone on respiratory machine? (From lecture)
Nurses/doctors must wear masks/gloves
Hair tied back
Must ensure air pressure is optimal and patient is quarantined
What is the mechanism of action for glycopeptide antibiotics ?
Bind to peptide chains on bacterial cell walls
Which of the following proteins are NOT encoded by viral genomes?
Capsomere, Proteases, 30S ribosomal subunit, RNA polymerase and Reverse Transcriptase
30S ribosomal subunit - it is the only component on the host (absent from virus)
Do viruses have ribosomes?
No
Which method of sterilisation is most effective in clinical scenarios?
Moist heat up to 121 degrees Celsius for 15 minutes
Detergent/alcohol used for disinfection, not sterilisation
Virulence factos for staphyloccus aureus?
Cell wall polymers to prevent immune cell recognition (eg peptidoglycan)
Cell surface proteins to bind to host cells (eg protein A)
Toxins to lyse open host cells (eg enterotoxins)
Antibiotics resistant genes to promote multidrug resistance
Are UTI considered normal or opportunistic infections?
Opportunistic, as the tract is usually sterile of bacteria. Tends to opportunistically infect patients in hospitals who have limited mobility and utilise catheterisation; thus increasing chances of infection
Difference between sterilisation and disinfection?
Sterilisation is the killing or removal of all viable organisms (and spores), while disinfection is the killing of many, but not all microorganisms
Four main sterilisation methods?
Irradiation, UV radiation, Pasteurisation and filtration
Conditions for moist heat sterilisation?
121 degrees celcius, 15 minutes
Conditions for dry heat sterilisation?
180 degrees celcius, 1 hour
What gamma wave frequency is used for sterilisation?
4.5 MRads
What size is UV radiation?
250-260nm
Conditions for pasteurisation?
Heat then rapid cooling
Standard - 62 degrees C for 30 mins
Flash - 71.5-74.5 for 15 secs
Ultra high - >135 degrees for 1-2 secs
Difference between protective isolation and course isolation?
Protective - for a vulnerable patient and has positive air pressure
Source isolation - for an infectious patient and has negative pressure
