ic5 Flashcards
benefits of microorganisms
1) food production
2) energy production
3) cleaning up the environment
4) sustaining agriculture
5) production of useful gene products
6) constitute human microbiome
microorganisms as harmful infectious agents
1) virulence: ability to multiply and grow
2) invasiveness: ability to enter host/tissue
3) pathogenecity: ability to cause disease and infections
chain of infection
1) infectious agent (bacteria, fungi, virus)
2) reservoir (where they reside, survive, reproduce)
3) portal of exit (infectious agent leaves reservoir)
4) modes of transmission (how infectious agent transfers from 1 carrier to another)
5) portal of entry
6) susceptible host
. each link of the chain must be connected for infection, break any link stops transmission
healthcare-associated infections (HAIs)
. infection acquired during care delivery in hospitals/healthcare facilities
. preventable (appropriate use of invasive devices, antibiotics, sanitation, waste management, environmental cleaning, adequate staffing to avoid crowding, consistent hand hygiene practices, infection prevention control (IPC) guidelines
critical roles of IPC
ensure safety & quality, improves healthcare outcomes
meets international, national, and local health priorities
5 moments for hand hygiene
1) before touching patient
2) before clean/aseptic procedure
3) after body fluid exposure risk
4) after touching patient
5) after touching patient surrounding
alcohol based hand rub
preferred method
effective against most important pathogen
more convenient, increase compliance
hand washing with soap and water
recommended when hands visibly soiled, after caring for patients with known/suspected infectious diarrhoea
principles of PPE usage
1) hand hygiene before & after wearing PPE
2) put on before contact with patient
3) remove immediately after completing task
4) never reuse disposable ones, clean and disinfect reusable PPE between each use
5) change PPE if contaminated/damaged
6) should not be adjusted/touched during patient care
when to use mask, eye protection and face shield
. protect mucous membranes of nose and mouth
. masks should be worn by coughing patient when outside room
. surgical/medical mask discarded after each use/changed when moist/soiled
dealing with needles/sharp objects
DO NOT
recap used needles, manipulate used needles/sharps by hand, pass sharps directly from hand to hand, overfill sharp containers
DO
dispose used needle & syringe as one unit
discard sharps into puncture-resistant disposable container
ensure sharp containers are securely closed & handled
forms of contact transmission
direct: touching
indirect: transferred via contaminated objects
diseases that spread through contact
clostridium difficile diarrhea, infectious diarrhea, scabies, pediculosis (head lice), shingles, antibiotic-resistant (MRSA, VRE, CRE)
contact precautions
1) patient placement: single rooms with dedicated toilets and sinks/cohort with those infected with the same microorganism
2) PPE: disposable gown & gloves before entering patient room/when body or close contact, wash hands after gloves & gown removal after exiting room
3) frequently touched surfaces cleaned & disinfected between patient use
4) equipment & linen: avoid sharing equipment, linen handled per hospital infection control protocol
5) patient transport: minimise transport, accompanying staff dont need gloves & gown, transport equipment cleaned thoroughly
6) communication: identify patients per hospital protocol
droplet transmission
SARS-CoV-2, adenovirus, rhinovirus, Bordetella pertussis (whooping cough), Haemophilus influenzae type b (Hib), influenza, mumps, rubella (german measles), Group A Streptococcus (1st 25 hrs of antibiotic therapy)
droplet precautions
1) patient placement: ideally single rooms/beds spaced at least 1.5m apart
2) PPE: surgical masks before close contact, hand hygiene before putting on & removing masks
3) environmental control: frequently touched surfaces cleaned & disinfected between patient use
4) equipment & linen: avoid sharing equipment, linens handled per hospital infection control protocol
5) patient transport: minimise transport, accompanying staff and infectious patient wear surgical mask during transport
6) communication: clear signage displayed at entrance of patient’s room
airborne transmission
. infectious agents < 5 microm
minute droplets generated when infected person cough/sneeze/talk -> droplets suspended in air for long periods of time -> droplets inhaled by susceptible host
. obligate: transmitted only by deposition of droplets in air under natural conditions (e.g. pulmonary tb: mycobacterium tb)
. preferential: predominately transmitted through airborne route but can be transmitted by multiple routes (e.g. chicken pox: varicella zoster virus, measles: rubeola)
airborne precautions
1) patient placement: airborne infection isolation room with special air handling & ventilation system. negative room pressure, unidirectional inward airflow from environment to room
2) PPE: N95 masks/higher level respirators, hand hygiene before & after removal
3) environmental control: frequently touched surfaces cleaned & disinfected between patient use
4) equipment & linen: avoid sharing equipment, linen handled per hospital infection control protocol
5) patient transport: minimise transport if possible, accompanying staff & patient wear N95/higher level respirator during transport
6) communication: clear signage displayed outside isolation room
airborne precautions visitors
. generally: enter wearing surgical mask if immune, enter if N95 fitted if not immune
. special considerations for pulmonary tb: household contacts exposed, no need N95 but need surgical (Screened for signs & symptoms of active infection), non-household contacts discouraged from visiting
. special considerations for chickenpox & measles: household contacts no need N95, surgical masks, screened for signs & symptoms of active infection, non-household contacts without immunity should not visit
prokaryote vs eukaryote
prokaryotes smaller, lack nucleus & other membrane bound organelles
eukaryotes larger, has nucleus & other membrane bound organelles
types of microorganisms
prokaryote: bacteria
eukaryotes: fungi, protozoa, algae
acellular: virus
virus
. smallest infectious particles (18.600nm)
. no cellular structure ( no cell wall, plasma membrane, ribosomal structure, only nucleic acid core & protein coat, replicate in other living cell)
. e.g. measles, mumps, rubella, influenza, chicken pox, hepatitis , hand foot mouth
fungi
eukaryotes
cell wall, well-defined nuclei & other organelles (e.g. mitochondria)
3 forms: 1) unicellular (yeast) 2) filamentous (mold) 3) diamorphic (exist in either yeast/mold form)
e.g. dandruff (malassezia furfur), athelete’s foot (tinea pedis), vaginal yeast infection
bacteria general
prokaryotes
cell wall, lack well-defined nuclei & other organelles
vary in 1) size 2) shape 3) spatial arrangements
gram stain
1) Apply primary stain (crystal violet), bind to thick peptidoglycan cell wall, stain cell purple (+)
2) apply iodine, bind to crystal violet, form crystal violet-iodine complex
3) apply counter stain (Safranin), stain cell pink (-)
acid-fast stain
presence of acid fast bacilli, some bacteria resistant to gram-stain
blue: acid-fast negative
red/purple: acid-fast positive
classifying bacteria by shape
spherical: cocci
rod: bacilli
spiral: spirilla
comma: vibrios
corkscrew: spirochaetes
bacteria classification by morphology
Staphylococcus: clusters
Streptococcus: pairs & chains
bacteria classification by oxygen requirement
obligate aerobes: need oxygen
obligate anaerobes: generate energy without oxygen
faculative anaerobes: grow in both presence & absence of ocygen
aerotolerant anaerobes: fermentation produce ATP
