week 5 material Flashcards
what is fungi
- eukaryotic
- heterotrophic
- cell wall: chitin + beta-glucan
- cell membrane: ergosterol
what are examples of fungi and their morphology
Yeasts, Mold, Dimorphic Fungi
Yeasts
- single cells
- reproduces via budding
Mold
- multicellular bodies
- made up of filaments (protein) called *hyphae**
- Septate Hyphae can have walls between hyphae
- Nonseptate Hyphae does not have walls between hyphae
Dimorphic Fungi
- can be either yeasts or mold - depends on environment
- 25 degrees = mold
- 37 degrees = yeast
How does fungi reproduce
Asexual - Mitosis
- budding
- fragmentation of hyphae (split of hyphae = new individual)
Sexual - Meiosis
- creates spores
where does fungi grow
Saprobes = take take in the nutrients of dead + decaying matter
- 300 of fungal species are human pathogens
- fungus that grows at 37 degrees is considered to be pathogenic in a immunocompromised host
where is the human mycobiome found
mycobiome = group of fungi that is found in the body
- oral cavity/mouth
-lungs - gastrointestinal
- skin
human mycobiome and risk of disease
the fungi in your mycobiome can increase the your risk of having a disease
- this occurs when the healthy microbiome is disrupted or when the immune system is weakened
Example
- getting thrush after taking antibiotics or have immunodeficiency
compare + contrast fungi and bacteria
Bacteria
- prokaryotic
- 1-3 um
- polysaccharide capsule - for some bacteria it acts as a virulence factor
- cell wall has peptidoglycan
- cell membrane has NO ergosterol
- 70S ribosome
- single chromosome, plasmids
- aerobic or anaerobic
- binary fission
Fungi
- eukaryotic
- 3-10 um
- some species also has capsule
- cell wall has chitin and glucan
- cell membrane has ergosterol
- 80S ribosome
- chromosome is in nucleus
- mostly aerobic
- reproduces via budding, linear extension of hyphae, production of spores (conidia)
what diseases does fungi cause
Hypersensitivity
- allergic reaction to molds + their airborne conidia (spores produced by mold)
Cutaneous Infections (skin)
- infect the keratinized layer of hair, skin, nails
- dermatophytes - leads to tinea cruris, onychomycosis
Systemic Mycoses
- able to disseminate (spread) regardless of immune system
Opportunistic Infections
what are virulence factors used by fungi
Adhesions
- allow fungi to adhere to endothelial cells to invade tissues
Capsule
- encapsulated organisms are resistant to phagocytosis + can allow for organism to easily pass into the central nervous system
Biofilm production
- can create biofilm
- ability to adhere + embed in biofilm to protect itself
Melanin
- some fungi has melanin in their cell walls
- makes them resistant to phagocytosis + killing
Shape shifters
- they’re able to grow in different tissues forms which makes it easier for them to invade the tissue
Thermotolerance
- able to grow at 37 degrees
are most fungi communicable
no - they are exposed everywhere but people do not become sick due to a strong immune system
Exceptions
- some fungal skin infections
how can we diagnose fungal infections
Lab techniques
- microscope + culture
- silver stain - visualizes fungi (stains black against green background)
Molecular methods
- PCR
- MALDI-TOF
Serology/antigen detection
- Galactomannan (an antigen test for the polysaccharide in the aspergillus’ wall)
Imaging modalities
- CT
- MRI
what are the antifungal agents
Polyenes
- binds to ergosterol to create pores in the cell membrane
- causes cell leakage and death
Azoles
- stops ergosterol synthesis
- disrupts the formation of the cell membrane
Echinocandins
- stops beta-D-glucan synthesis
- beta-D-glucan is a component of the cell well
- leads to cell lysis
what are the different host factors that can cause for someone to be susceptible to an opportunistic infection
- poor nutritional status
- diabetes
- substance use
- age
for a barrier disruption
- foreign bodies
- burns
- severe rash
for innate immunity
- inherited immunodeficiencies
- chemo
for adaptive immunity
- inherited immunodeficiencies
- HIV
- chemo
- cancer
- corticosteroids
- medication (immunosuppressive + transplant)
what is an opportunistic infections and where it can occur
when a disease occurs due to the body being compromised or weakened
it can occur in the..
- body’s protective mechanisms
- the immune system
- the normal microbiota is affected
what are examples of fungal infections
- candida spp
- aspergillus fumigatus
- pneumocystis jirovecii pneumonia
what is Candida Spp and what disease does it cause
- yeast
- it causes opportunistic infections in humans
- part of normal flora of
- mouth
- GI tract
- genital tract
creates the disease Candidiasis
- can be a invasive infection (Candidemia - bloodstream) or a superficial (oral or vaginal)
This occurs due to these risk factors in the host cell
- if the person has an impaired innate or T-cell immunity
- if the person has prolonged antibiotic therapy which destroys the balance of normal microbiota + causes overgrowth of endogenous candida
- disruption of normal anatomic barriers - due to cardiac/ab surgeries, use of central venous catheters
what is aspergillus fumigatus and what diseases can it cause
- mold found in the environment
- environment: soil or decaying matter
- a septate hyphae
- a hyaline molds
- has a sporing head called conidiophore
- creates spores that are easily inhaled + can cause infection
Diseases
- allergic hypersensitivity (asthmatics)
- aspergilloma (fungal balls develops in the chest’s cavity)
- invasive disease in immunocompromised individuals
what are the risk factors, diagnosis, and treatment of aspergillus fumigatus
Risk Factors
- neutropenia
- hematologic malignancies
- corticosteroids
Diagnosis
- culture
- microscopy
- galactomannan (biomaker) - polysaccharide in fungal cell wall
Treatment
- voriconazole (antifungal)
how can we prevent people from getting infected with aspergillus fumigatus who are high risk
with the environment
- restrict access to construction sites
- air filtration
- no flowers or plants brought in
with host
- avoid risk behaviours (plant or mould exposures)
- the antifungal prophylaxis in the highest risk patients
what are opportunistic infections for people with HIV
- includes parasites, bacteria, fungi, and viruses
- most susceptible to opportunistic infection when CD4 cells amount go down to 200
what is pneumocystis jirovecii pneumonia
- risk factors
- presentation
- diagnosis method
- treatment
- prevention
- aka PCP
- yeast
- causes pulmonary disease in immunocompromised patients
Risk Factors
- HIV when CD4 count is below 200
- already had PJP before
- immunosuppressive therapy
Presentation
- insidious pneumonia
- occurs over works weeks
- causes low oxygen levels
Diagnosis Method
- silver stain of bronchoalveolar lavage
- PCR
Treatment
- trimethoprim-sulfamethoxazole
Prevention
- start antiretrovirals
- may need low dose septra
how do we treat fungal disease
using antifungals that use selective toxicity
targets the cell membrane (ergosterol)
targets the cell wall (beta-glucan)
treatments rely on improved immune systems in the host
what kind of infections are associated with substance use
- bacterial infections
- viral infections
- STI
bacterial infection + examples
- associated with HIGH readmission, infection recurrence, and death
influenced by these characteristics:
- age 25-65
- female
- has HIV
- using specific substances
Bacteremia = bacteria in bloodstream
- see it in people who inject drugs
Infective endocarditis= infection of the lining of the heart + the valves
Osteomyelitis - infection of bone
viral infections
- injection drug use was the primary exposure for HIV in 21% of new HIV cases in 202
- crystal meth has been linked to an increase in risk of HIV seroconversion
- injected drug use + non-injection use has been associated with having hep C
- injection drug use is a risk factor for acute hep B infections (most common one in the US in 2020)
STI
people who inject drugs engage in riskier sexual behaviour
drug use groups + sexual groups overlap
- alcohol + sexual contact = associated to increased risk of syphilis
- cocaine + experiences with sex work were tied to past syphilis outbreaks but recent evidence has shown otherwise
- injection drug use is associated with syphilis risk
- crystal meth
what social + structural factors influence infection risk
changing, unregulated drug supply
- people thought they were consuming a certain drug but was actually laced with something else
lack of safe spaces + equipment
racism, stigma, and discrimination
what is harm reduction
practical strategies, ideas and practices that ensure that we’re reducing the negative consequences of drug use
- accepts that drug use exists - works to minimize the harm associated with it rather than ignore it
- acknowledge that there are continuous behaviours associated with drug use
- our goal is a good quality of life and well being at the individual level and the community level
- not providing services with force or judgement
- people who use drugs should have a say in programs that treat them
- people who use drugs are the primary agents of change
- we have to recognize that social inequities that are tied to and impact substance use and treatment
- does not attempt to minimize or ignore the harms from substance use
what are the materials used to do drugs safely
tourniquet = decreases risk of missing injection
alcohol skin wipes = decreases the chances of the microorganisms living on the skin to get into the body
sterile water = decreases risk of waterborne pathogens getting in
cooker + filters = decreases bacterial + pathogen burden
**vitamin C* = decreases risk of fungal infections + vein damage
sterile needles = decreases the need to share or reuse
