MICRO-ORGANISM & CHAIN OF INFECTION Flashcards
(22 cards)
HEALTHCARE ASSOISATED INFECTION (HCAI)
- develops as a result of healthcare interventions
- transmitted via blood, body fluids or excretion:
Can result from:
> contact with non-intact skin/mucous membrane
> equipment that could be contaminated
> Inhalation of droplets/airborne infections
> inoculation incidents - HC infections, existing or underlying conditions = delay recovery and affect quality of life.
RESULTS IN INCREASED:
- lenght of stay
- morbility & morbility
- finacial resources
FACTORS AFFECTING RISK OF ACQUIRING HCAI
MAIN CLASSIFICATIONS OF MICRO-ORGANISM THAT CAUSE DISEASE
- fungi
- viruses
- bacteria
- protazoa
SOME EXAMPLES OF HCAI
- MRSA
- MSSA
- E COLI
INFECTION VS COLONISATION
COLONISATION: bacteria on the body surface without causing death
INFECTION: pathogens/disease causing micro-organism gaining access to host tissue and immune resposne
SIGNS OR SYMPTOMS INDICATING INFECTION RATHER THAN COLONISATION
- heat
- swelling
- redness pain
- loss of function
- fever
- increased heart rate
- high white blood cell count
DEFINITIONS
COMMENSAL: microbes live in close proximity with their host & in the correct environment don’t harm it & positively benefit
PATHOGEN: a microorganism able to cause a disease
PATHOGENICITY: causes disease in a host organism
PATHOGENESIS: a process of which microorganisms produce disease
VIRULENCE: degree of pathogenictiy
MICROBIAL FLORA
- Resident flora is less likely to be associated with infections
- cause infections in the sterile body cavity, eyes or on non-intact skin
- Transient flora (transient microbiota) colonises the superficial layer of the skin, and is more amenable to removal by routine hand hygiene
SKIN LAYERS: RESIDENT (deeper layers of skin), TRANSIENT (superficial layer of skin)
FLORA: RESIDENT (permanent, found in specific areas) TRANSIENT (temporary flora)
DISTRUBANCE: RESIDENT: (if disturbed = re-established) TRANSIENT ( usually don’t re-establish)
HANDWASHING: RESIDENT (not removed by handwashing) TRANSIENT (more easily removed by handwashing)
TRANSMISSION: RESIDENT (difficult) REANSIENT (easy)
WHAT IS REQUIRED OF A MICROBE TO ESTABLISH INFECTION IN A HOST
- gain access to a host
- enter and move to the more favourable site within the host tissue
- penetrate or evade host defence in order to multiply
- dissemination of new pathogen in or out of host
CHAIN OF INFECTION
WHAT MAKES MICRO-ORGANISMS GOOD PATHOGENS
- flagella for movement
- multiple bacteria grouped together
- spores - enhanced ability to survive in unfavourable conditions
- Fimbria - enhanced adhesions to the surface
Examples of bacteria:
- ataphylococccus aureus
- Vibrio cholera
BACTERIAL STRUCTURE
pH AND MICROBIAL GROWTH, TEMPERATURE AND MICROBIAL GROWTH, OXYGEN AND MICROBIAL GROWTH
- Organisms live in a variety of conditions, which they adapt to
- neutrophiles in terms of pH; however, some can live in a more acidic environment, i.e. Such as the smotach
- temperature in humans: thermophiles
- O2 is a varaible amoung organisms
CHAIN OF INFECTION - CLOSTRIDIUM DIFFICILE
- Susceptible host
Antibiotic exposure disrupts gut microbial flora
Older people
Healthcare environments
Immunocompromised
Serious underlying illness
Long stay in hospitals - Portal of entry- mouth
- Organism (virulence)
Anaerobic bacteria
Spore producing
Toxins cause inflammation of the gut mucosa
‘pseudomembranous colitis’ - Source/reservoir
Microbial flora of the large intestine
Equipment and environment
Can survive as spores for weeks to months - Portal of exit - GI tract – spores excreted in faeces
- Transmission
Faecal-oral route
Person to person ( hands)
Contact with environmental surfaces
spores-producing bacteria = harder to remove from the clinical environment
- exposed to air
- spore resistant & tolerant air, heat, detergents and disinfectants
e.g toleits, surfaces, around beds
alcohol hand fel is not effective better to use soap and water
COMPONENTS OF VIRUSES
- NUCLEIC ACID CORE (DNA OR RNA)
- CAPSID: protective protein composed of capsomers
- ENVELOPE: some viruses have an additional lipoprotein membrane with glycoprotein spikes
- Enveloped virsues dont protect from the envelope = higher chance to breaking from infection control processes
CAHIN OF INFECTION - CORONAVIRUS
- Susceptible host: Older people
Healthcare environments
Community
Immunocompromised
Serious underlying illness
Black ethnic groups
Obesity - Organism (virulence): Spike proteins
Envelope - Source / reservoir: Carriers - asymptomatic, Respiratory tract – nose, mouth and throat. Surfaces or contaminated objects can last from hours to days (depending on ambient temperature)
- Portal of exit: Respiratory tract – aerosols from speaking, singing, coughing and sneezing
Aerosol generating procedures - Transmission: Person-to-person direct contact ( hands)
Contact with environmental surfaces - Portal of entry: Respiratory tract breathing in aerosols – mucus membranes nose or mouth and eyes
Touching contaminated objects from droplets and then touching eyes, nose or mouth
FUNGI: YEASTS
CHAIN OF INFECTION - CANDIDA ALBICANS
- Susceptible host: Immunosuppressed
Taking immunosuppressive drugs
Medical devices in immunosuppressed e.g IV lines, catheters and drains, can lead to systemic disease
Antibiotics. Changes in the acidity of the mucosa - Organism (virulence)
Can live as a yeast ( dissemination) and also produce hyphae ( hyphae are more associated with the invasion of tissues) - polymorphic
Uses budding to reproduce and disseminate infection in the body
Produce proteins which help with attachment ( adhesins)
Produce enzymes to break down proteins and lipids
Can adapt to pH environment - Source/reservoir: Mucosal surfaces: Mouth, GI tract, vagina
Part of the normal microbial flora - Portal of exit: Secretions from the mouth
Skin (Digestive tract) - Transmission: Person to person
Rarely sexual transmission: Babies acquire C albicans during vaginal birth - Portal of entry:
Mouth
vagina - Can cause localised infection or systemic life threatening infection
- Opportunistic infection in susceptible host
ANTI-BACTERIAL MEDICATIONS AND WHERE THEY ACT
ANTIFUNGAL MEDICATIONS AND WHERE THEY ACT
ANTI VIRAL MEDICATIONS AND HOW THEY ACT
