Infection Control, Specimen Collection & Specimen Processing Flashcards
What are laboratory functions
Diagnostic
Epidemiological
Describe diagnostic lab function
Detection of infectious agents, guidelines for treatment
Information for individual cases
Collated info for general use
Describe epidemiological lab function
Information provided can be used to complement clinical info
Track resistant isolates
Follow trends
Detect or confirm outbreaks
Support control efforts and public health
How can you make the best use of the lab
Appropriate specimens collected
Label properly to decrease frustration
Be cost effective
Eliminate delays
What are general principles of specimen collection
Send good quality specimens
Avoid contamination
Label with patient name, birthday and health number
Put relevant info on the requisition
How can you maximize sample quality
Use appropriate transport media
Get specimens to lab asap
Work WITH the lab
What are the types of urine collection
Mid stream (most common)
In out catheter
Indwelling catheter
Describe mid stream collection
Avoid touching skin
Pass a few millilitres then collect specimen in clean sterile container
How long should you wait to bring urine specimen to lab
No transport media needed if at lab within 2 hours or refrigerated at 4c and delivered within 24 hours
Describe in/out catheters
Insert catheter
Discard first few ml
Collect the specimens and submit
Describe indwelling catheter
Collect specimen using needle and syringe after cleaning collection site with alcohol
What are types of respiratory tract specimens
Sputum (most common) Induced swelling (If dry cough) Tracheal aspirate (using tube)
Describe sputum collection
Cleanse mouth with boiled water
Avoid post nasal discharge
Deep cough from chest
DRY STERILE CONTAINER get to lab within 24 hours or refrigerate 4c
Contamination detected by squamous cells
Describe induced sputum
Induction of sputum using saline aerosols
Looks watery
Dry sterile container
Describe tracheal aspirate
Useful in intubated patients
Specimen collection traps more prone to leaking during transport
What are patient instructions for stool collection
Pass stool on clean dry surface (paper)
Place almond sized portion in the specimen container
How is stool transported for culture
Cary Blair transport medium; keeps things alive but does not let it grow
How is stool transported for parasite detection
SAF preservative
Formalin’s
How is stool transported for cytotoxicity and virology
Dry sterile container
When are swabs used
Throat
Wounds
Urethra
Not for abscesses, fluid or TB culture
What are other kinds of specimens
Tissue Pleural fluid Pericardial fluid CSF Vitreous fluid
All collected in dry sterile container
Microbiology specimens should never be put in _____________
Formalin
It kills all bacteria
When are results usually available
Microscopy usually available within 1-2 hours for stat samples
Cultures can take a few weeks but usually 3-5 days
Describe rapid testing
Usually detect an antigen
Causes particles to agglutinate or create colour
Mistakes in technique can cause incorrect results
Sensitivity sacrificed for speed
Describe microscopy
Gram stain most commonly used
Used for diagnosis
Less sensitive than culture
Assesses quality of specimen (Q scoring)
Types of cells (squamous cells) used to infer contamination has occurred
Describe media
May be liquid (broth) or solid (plates)
What is broth used for
Detecting very low numbers of organisms
Increasing the number of a type of organisms in a specimen (enrichment)
Biochemical testing
Describe solid media
Usually agar
Isolating colonies of bacteria can detect low numbers
Can be:
Differential: distinguish colonies
Selective: species inhibited from growing
Fairly sensitive
Describe blood agar
Contains 5% sheeps blood
Allows detection of hemolysis
Describe chocolate agar
Cooked blood More nutritious (H. Influenzae grows)
Describe MacConkey medium
Contains bile salts and crystal violet to inhibit gram positive organisms
Lactose fermentation detected
Used for stool and urine specimens
Describe blood cultures
Innoculated at bed side into bottles with some sterile fluid
2 sets taken aerobic and anaerobic
Most labs use automated systems for monitoring
Keep at room temp until placed on machine
Needs to be on machine within 18 hrs
Describe incubation conditions
Atmosphere
Temperature
Describe usual atmosphere conditions
Aerobic (ambient air)
Micro aerobic 2-5% oxygen (ex campylobacter)
Anaerobic <1% oxygen
Describe usual incubation temperature
Most often 35°
Describe colony
Growth of bacteria on a solid medium
Appearance useful
Presence of haemolysis
Pigment
Describe biochemical identification
Based on the enzymes an organism is actively expressing
Profile typical of each species
Once most commonly used method
What is MALDI
Spectrometry
Colony and matrix is vaporized and analyzed
What are other identification methods
Identification of specific antigens on the organisms surface (agglutination/immuno fluorescent microscopy)
Molecular methods (genome sequencing/nucleic acid probes)
What is susceptibility testing
Determines which antimicrobials are likely to be less effective against an individual strain
Doesn’t take into account the ability of a persons defences against attack
A prediction
What are susceptibility testing methods
Expose organism to concentration of anti microbial (disc, broth, dissolved in agar)
Lack of growth indicated inhibition (minimal inhibitory concentration)
What are other susceptibility testing methods
Detection of enzymes that break down antimicrobials (beta lactamase)
Molecular means
What are further testing methods
Typing can be useful to determine relationship of organisms:
Serotyping
Molecular typing (whole genome sequencing, pulsed field)
Antibio gram and bio type
What is the epidemiologic triad of disease
Host
Agent
Environment
What are the links of the chain of transmission
Agent Reservoir Portal of exit Mode of transmission Portal of entry Susceptible host
Describe the agent (pathogen)
First component in the chain of infection
Important characteristics: ability to multiply, ability to withstand environmental stress
Human or non human reservoirs
When are agents epidemiologically important
Transmitted
Causes infection
Produces clinical disease
What are characteristics of agents
Infectivity: ability to enter survive and multiply within the host
Pathogenicity: extent to which disease is produced
Virulence: serious disease producing potential
Describe a reservoir
Place where agent lives and replicates
Must be able to exit reservoir and enter susceptible host via portal of entry
What are the 5 modes of transmission
Contact (indirect or direct) Droplet (large propelled over short distance) Common vehicle Airborne Vector borne
Describe a susceptible host
Person or other living animal that affords lodging to an infectious agent
Definitive (primary): parasite reaches maturity
Intermediate (secondary): in which a parasite is in its larval stage
Describe basic reproduction number
R= CQD C = contact rate Q= probability of tranmission D = duration of infectivity
Incorporates social and biological determinants of transmission
What is a nosocomial infection
Health care associated infection
What are the most common nosocomial infections
Uti (MOST COMMON)
Surgical site
Pneumonia
Bacteremia
What are examples of multi drug resistant organisms
Nosocomial infections: MRSA VRE C DIFF CPE Candidia Auris (newest)
What does good hand hygiene do
Reduces nosocomial infections by 40-50%
What are the 4 moments of hand hygiene
- Before patient/environment contact
- Before aseptic procedure
- After body fluid exposure
- After patient/environment contact
What are 3 principles of precautions
You can not easily tell who has what
Body substances of all patients considered infectious
Behaviour is determined by risk of encountering substance
What are routine precaution practices
Based on point of care risk assessment
What are additional precautions
Contact
Droplet
Airborne
What are components of infection prevention and control
Elimination (isolation/quarantine)
Engineering/environmental controls (ventilation, barriers, cleaning, separation)
Administrative controls
What are some interventions/preventions
Infection prevention and control (IPAC)
Surgical site infection
Ventilator associated pneumonia
Central line blood stream infection
