MPHA 5P07 Test 1

What is medical microbiology

-focuses on the study of microorganisms such as parasites, fungi, bacteria, viruses, and prions and their relationship to human health and disease

Where are normal flora in the body? How do organisms evade the immune system?

-live symbiotically in and on the host

-genitourinary tract(urethra), GI tract (location dependent), respiratory tract, eyes(transient from skin), mouth (hygiene dependent), female genital tract(age dependent), skin(skin condition dependent)

What is a the difference between communicable and infectious diseases?

-communicable means they can spread directly or indirectly from one person to another

-infectious is caused by microscopic pathogens

-all communicable diseases are infectious but not all infectious diseases are communicable

Potential vs Strict pathogen

-potential are capable of causing disease when there’s an imbalance in host immune system

-strict are not normal flora and when they colonize the host, they cause disease

What is pathogenicity and how do some organisms thrive in certain circumstances?

-Pathogenicity is the ability of a microorganism to cause disease in a host

-organism translocation into sterile space

-potential pathogens can be pathogenic when host’s natural defenses are compromised

How do some pathogens evade the immune system and\or avoid phagocytosis?

-opsonization is prevented bc organism has a capsule

-biofilm(slime layer), some can stick to foreign objects

-phagolysosome fusion inhibited

-escape into cytoplasm

-resistance to killing

-antigenic variation

What are stages of an infectious disease?

-incubation phase: intro of organism to onset of illness

-active phase: infecting organisms are multiplying and causing damage

-convalescence phase: recovery after illness

-diseases are either acute, chronic, and latent

-some people are covalent or asymptomatic carrier

-reservoirs can be human, non-human, or enviornmental

What are some characteristics of infectious disease agents?

-infectivity, pathogenicity, virulence, toxigenicity, resistance, antigenicity

What are the innate and adaptive immune response?

-innate is from birth, no memory cells, nonspecific

-acquired is specific, either humoral or cell mediated

Why is IPAC important?

-prevent infections

-manage infections effectively when they occur

-limit the development of antimicrobial resistance (AMR) through prudent use of antimicrobials as part of effective antimicrobial stewardship (AMS)

-promote appropriate and sustainable use of IPC resources

What is colonization and infection and how do they differ?

-colonization is sustained presence of replicating infectious agents on, or in, the body but w/o any evidence of infection or disease

-infection is invasion by, and reproduction of, infectious agent + causing disease

What is the Chain of Transmission and why is it important to break it?

-six elements: agent, in the reservoir, exits the reservoir through a portal of exit, travels via a mode of transmission and gains entry through a portal of entry to a susceptible host

-chain be broken at any point: agent eliminated so no exit of reservoir, portals of exit contained, prevention transmission, portal of entry protected, host not susceptible

What are different modes of transmission?

-contact: direct or indirect physical contact

-droplet: large respiratory particles

-airborne: smaller particles, can be carried long distances

-vehicle: spread through contaminated inanimate objects

-vector-borne: spread through living organisms

How did some precautions historically become routine?

-precautions introduced in 1985 by CDC due to HIV epidemic

-guidelines focused on blood and blood contaminated body fluids, however not other fluids yet

-include: use of barrier precautions, PPE, stuff to prevent injury from contaminated needs etc, protocols for blood spills

-PHAC made guidelines in 1999 and they updated in 2017

What are some routine practices?

-based on the premise that everything is potentially infectious

-five elements: risk assessment, hand hygiene, PPE, environmental controls, administrative controls

-performing a point of care risk assessment (PCRA)

What are some additional precautions that are also practiced? Some examples?

-specialized accommodation: separation or sometimes cohorting

-Signage: info on additional precautions

-PPE: gloves, gown, shield etc.

-Dedicated equipment + cleaning measures

-Limited transport: in certain areas, sometimes only transport where necessary

-Communication: staff family, facilty etc

-ex. contact, droplet, airborne

How long do additional precautions continue and what stops them?

-usually there are policies in place for duration

-should remain in place until no longer risk of transmission

-sometimes expert consultation needed

What are some characteristics of bacteria and their external structures?

-microscopic and unicellular, DNA units called plasmids, replicate via binary fission

-capsule

-slime/biofilm

-spores

What are the classifications for bacteria based on response to oxygen

-obligate aerobic bacteria

-microaerophilic: oxygen for growth but survive in atmospheric air sometimes

-facultative: presence or absence of oxygen

-facultative aerobic: oxygen for ATP

-facultative anaerobic: ATP by aerobic respiration but fermentation when no oxygen

-obligate anaerobic

-aerotolerant: can survive but not use oxygen

What are the classification for bacteria in terms of morphology?

-cocci

-bacilli

-spirilla

What is a way to distinguish groups of bacteria?

-staining, especially gram staining

-gram negative stain pink and gram positive stain purple

What are some cell wall similarities or differences of gram bacteria?

-gram neg has outer membrane

-cell wall is cross-linked of NAG and NAM

-periplasmic space is present in both types

-both have a cytoplasmic membrane

What are some aerobic gram positive bacteria?

-Staphylococci and Streptococci

-Enterococci

What are some anaerobic gram positive bacteria?

-Listeria Monocytogenes

-Corynebacterium

-Bacillus anthracis

-Actinomycetes

-Propionibacterium

-Lactobacilli

-Actinomyces Spp.

-Clostridium Spp

What are some gram negative bacteria?

-Neisseria species

-Moraxella species

-Chlamydia species

-Rickettsia species

What is acid-fast stain?

-procedure used to detect a small group of organisms that do not readily take up dyes

-example is mycobacterium

What is a virus and its components?

-infectious particles that need host cell’s machinery

-genome: RNA or DNA, double or single strand, positive and/or negative sense

-capsid: protein shell

-envelope: proteins and glycoproteins

-size can range from 10nm - 100 uM

What is the virus replication cycle?

1.Attachment & Penetration/Uncoating

2. Entry: either endocytosis or receptor-mediated membrane fusion

3. Replication:

4. Assembly: in ER and Golgi apparatus

5. Release: either lysis or budding/exocytosis

What are virus replication methods?

-double stranded DNA use host RNA polymerase and sometimes have their own DNA polymerase

-ss(+) are directly translated

-ss(-) require RNA-dependent RNA polymerase, a (+) strand is made, and then it can be translated

How can viruses be detected?

-electron microscopy

-culture

-serology

-antigen detection

-PCR

What is Fungi and what are ways to contract fungal diseases?

-ubiquitous in nature but infection is defined as entry into body tissues followed by multiplication of the organism

-change to host: immunocompromised or antibiotics disrupt human microbiome

-change to environment: overwhelming number of fungi in area or soil displacement

What is the cell structure of Fungi?

-eukaryotic

-main body is made of hyphae that are intertwined with mycelium

-primary sterol is ergosterol and the cell wall is made of chitin

What are the groups of Fungi

-yeasts: divide by budding and grow relatively fast

-molds: replicate through the development of spores and grow through the development of hyphae

-dimorphic fungi exist as both

-notable dimorphic are Histoplasma capsulatum, Blastomyces dermatitidis + Coccidioides immitis

What type of infection do each type of Fungi cause?

-most yeasts or molds cause superficial infections while dimorphic cause more systemic infections

What are ways to detect Fungi infections?

-KOH mount

-Calcofluor

-Silver Stain

-Culturing

What are parasites and what makes infections persistent?

-organisms that live at the expense of their hosts

-what keeps them persistent: urbanization, more intensive farming systems, further land + marine development, inadequate effluent disposal, the emergence of drug resistance in parasites and their vectors

What is the difference between ectoparasites and endoparasites?

-ecto live on the outer surface of the host and need adaptations to access host-derived nutrients

-endo live in the host and cause infection, can be intercellular or intracellular

What are protozoa and some common intestinal protozoa?

-eukaryotic organisms that have developed complex subcellular features: amoebae, flagellates, ciliates, sporozoan

-intestinal: Entamoeba histolytica, Dientamoeba fragilis, Giardia lamblia, Cryptosporidium parvum, Cyclospora

What are Helminths and Arthropods?

-helminths don’t proliferate within hosts, life cycle has 3 stages (eggs, larvae, adults), eg. tapeworms

-arthropods are ectoparasites, nearly in every kind of parasitic relationship, either hematophagous or histophagus

What are ways to detect parasitic infections?

-stool specimen in preservative (formalin)

-detecting parasitic macromolecules by enzyme immunoassay (EIA)

-can do serology and staining of infected tissue