Micro Flashcards
Outline the requirements for successful infection control
Hand Hygiene. Hand hygiene is the most important measure to prevent the spread of infections among patients
Respiratory Hygiene/Cough Etiquette
Sharps Safety
Safe Injection Practices
Sterilization and Disinfection of Patient-Care Items and Devices.
Environmental Infection Prevention and Control.
Describe the difference between sterilization and disinfection, and give anexample method to achieve each of these
Sterilisation—the killing or removal of all viable organisms, including spores
* Method: Heat, Irradiation
Disinfection—the killing of many but not all microorganisms
* Method: pasteurisation, filtration, Chemical disinfectants
Describe the additional infectious disease risks associated with the health care environment
Potential routes of infection include:
* Airborne transmission (suspended particles)
* Respiratory droplets
* Direct/indirect contact
* Faecal-oral
Outline the infection control methods in place in health care settings
Standard precautions
* Hand hygiene
* Use of PPE where appropriate
* Environmental controls—waste management; routine cleaning; spill management
Describe why in-patients are more vulnerable
Healthcare environment Promotes atypical/resistant organisms compared to community-acquired
- Older & more vulnerable hosts
- Multiple routes of infection—frequent contact between patients-carers
- Use of antimicrobials
- Constant environmental pressure is selective for resistant organisms
- Promoted by ease of genetic transfer in bacteria
What to do if there is spill in healthcare setting:
Small spills (< 10 cm)
1. Wipe with paper towel;
2. wash with detergent and water;
3. disinfectant (e.g. sodium hypochlorite, alcohol wipe)
Large spills in “wet” areas
* Hose spill into sewerage system;
* Flush area with water and detergent;
* Disinfectant (e.g. sodium hypochlorite)
Large spills in “dry” areas
* Contain area of spill and decontaminate using chlorine
* Remove spill
* Clean area with water and detergent
* Disinfectant (sodium hypochlorite)
A staff member of a pathology laboratory was given a bacterial sample to identify. Under the microscope, the Gram-stained sample looked like pink/reddish rods. How would you describe the morphology of the bacterial cells?
Gram-negative Bacillus
This indicates that the bacterial cells are elongated and cylindrical in shape, resembling rods, as opposed to being spherical (cocci) or spiral-shaped (spirilla).
Are virus’ living organisms
Are not living organisms because they:
* Consist only of DNA or RNA and protein
* Are incapable of independent reproduction
* Are smaller than any cell (~0.1 �m)
* Have no cell membrane
* Do not have ribosomes
* Have few enzymes for metabolism
How are virus’s classified
Viruses are classified based on their genetic makeup (nucleic acid and arrangement of nucleic acid), structure, and symmetry.
Robert Koch theory
- The suspected pathogen must be present in all cases of the disease and absent from healthy animals.
- The suspected pathogen must be grown in pure culture
- Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal
- The suspected pathogen must be reisolated and shown to be the same as the original
What is the difference between moulds and yeasts?
Moulds are multicellular fungi, while yeasts are single cell fungi
What are the qualities of the perfect antimicrobial agent?
It needs to be pathogen-specific, with few/no side effects to the host.
Mechanisms of antibiotic resistance
Limiting uptake of antibiotic drug
Production of enzymes such as B-lactamases that can inactivate the B-lactam ring
Enzyme inhibitors that are used in combination with antibiotics to combat resistant bacteria
What is the appropriate personal protective equipment when dealing with infected patients that can transmit an airborne respiratory infection?
- Gloves
- Hand hygiene
- safety glasses
- Aprons/gowns
Surgical mask for: Carer, Patient during transfer
Observe respiratory hygiene and cough etiquette
Potential sources of infection in the health-care setting
Surfaces
* Door handles
* Taps
* Toilet seats etc.
Instruments
* Respirators
* Ultrasound probes etc.
Medical supplies
* Bandages
* Surgical instruments
* Ultrasound gel etc.
The first cells recruited from the blood to a site of tissue infection are
neutrophils
A patient becomes infected with Staphylococcus aureus bacteria in a wound to the skin of the hand. Naïve T cells would initially be activated by bacterial antigens at which site?
The draining lymph nodes
A staff member of a pathology laboratory was given a bacterial sample to identify. Under the microscope, the Gram stained sample looked like pairs of purple circles. How would you describe the morphology of the bacterial cells?
Gram-positive diplococci
What is a dimorphic fungus?
It is a fungus with two distinct phases: mould at room temperature and yeast at body temperature
Describes why infections in the health care setting are more difficult to treat than community-acquired infections?
Secondary bacterial HCAIs are often antibiotic or multidrug resistant, AND a health care setting often has a higher population of vulnerable patients.
Mechanism of antibiotic resistance
Enzyme inactivation and modification.
Modification of the antibiotics target site.
Overproduction of the target.
Replacement of the target site.
Efflux and reduced permeability.
appropriate personal protective equipment (PPE) to wear when dealing with infected patients that can transmit a respiratory infection via droplets?
gloves, gown, surgical mask and safety glasses, and practise good hand hygiene and respiratory / cough etiquette
As a health care worker, describe your training in terms of infection control?
understanding who the susceptible patients are, appropriate PPE, good hygiene practices and careful technique in between patients, waste management, understanding the different diseases and modes of transmission
The activation of naive T cells occurs in
The spleen and lymph nodes
Define the logarithmic phase of bacterial replication?
An exponential increase in bacterial cells.
During host-microbe relationships, commensalism is defined as
one organism benefits, the other is not harmed
After viral attachment to the host cell surface, what is the next fundamental stage of the viral lifecycle?
Uncoating to release the viral genome.
Both community and hospital acquired urinary tract infections are most frequently caused by which microbial pathogen?
Escherichia coli.
In nosocomial settings, which route of infection is NOT generally associated with hospital transmission?
vector-borne transmission
Systemic mycoses are defined as fungal infections that
grow and spread into internal organs
The role of adjuvants in vaccines is
To provide an innate immune stimulus.
Different growth phases in growth curve
Lag phase
Log Phase - exponential growth
Stationary Phase - bacterial colony plateaus
Death/Decline Phase
You are asked to grow up some Escherichia coli in the laboratory, using two different conditions:
Growth Condition 1: 37°C, shaking in rich medium
Growth Condition 2: 37°C, shaking in minimal defined medium
Describe the differences between both growth conditions and explain why there are differences.
Growth Condition 1: 37°C, shaking in rich medium
- optimal temperature environment
- shaking ensures even distribution & access to oxygen
- Rich medium means bacteria have access to all the nutrients they need, providing essentials for bacterial growth
Growth Condition 2: 37°C, shaking in minimal defined medium
- optimal temperature environment
- shaking ensures even distribution & access to oxygen
- minimal defined medium means that there is only the basic nutrients needed for bacteria growth, this means we will see a slower rate of growth than plate 1, although there are still optimal growth condition, just less nutrients.
How would you determine which regions of the growth curve demonstrate exponential growth?
The region of the growth curve where you observe the steep, upward-sloping portion is the exponential growth phase. This is where the bacteria are actively and rapidly dividing
Describe how healthcare type of environments can contribute to the incidence of infectious disease
Healthcare environment Promotes atypical/resistant organisms compared to community-acquired
- Older & more vulnerable hosts
- Multiple routes of infection—frequent contact between patients-carers
- Use of antimicrobials
- Constant environmental pressure is selective for resistant organisms
- Promoted by ease of genetic transfer in bacteria
Give TWO (2) medically relevant examples of health care associated infections (HCAIs) and explain why they are of significance.
- Central Line-Associated Bloodstream Infections (CLABSIs)
- Catheter associated UTI
Both increase morbidity/mortality, contribute to antibiotic resistance
How would you sterilise surgical equipment for surgical use
Sterilisation—the killing or removal of all viable organisms, including spores
* Method: Heat, Irradiation
How would you clean up a small biological hazard
- Wipe with paper towel
- Wash with detergent + water
- Disinfect (sodium hypochlorite or alcohol wipes)
If biological spill is under 10cm.
In what situation might achieving Koch’s postulates be impossible for a causative organism?
Non-culturable microorganisms: Some microorganisms, including certain viruses and unculturable bacteria, cannot be grown in laboratory culture. If the causative organism cannot be cultured and isolated, it becomes challenging to fulfil the first postulate, which requires the ability to cultivate the microbe.
Name and describe ONE (1) mechanism by which an antibiotic resistance gene can be transferred from one bacterial cell to another.
Horizontal gene transfer (HGT)
Once a bacterium mutates to become resistant to a antibiotic, it can pass that resistance to other bacteria around it via HGT through mobile genetic elements
