Laboratory Sciences 2nd Edition By Maria Dannessa Delost
infectious disease - ANSWER:- caused by pathogenic microorganisms
- can spread directly or indirectly between people
- one of the biggest causes of death globally
zoonotic disease - ANSWER:can be transmitted between animals and humans
epidemic - ANSWER:occurs when an infectious disease spreads very rapidly, affecting
a large population
pandemic - ANSWER:epidemic disease that has a global spread (e.g. black death,
swine flu, SARS-CoV-2)
importance of accuracy in diagnosis - ANSWER:- leads to appropriate treatment
- helps to avoid inappropriate antimicrobial therapy
clinical presentations - ANSWER:i. Symptoms
ii. Patient history (e.g. Intravenous drug users, HIV patients, CF patients etc.)
iii. Site of infection (e.g. eye infections, STIs etc.)
iv. Is there an outbreak
non-microbiological investigations - ANSWER:i. Radiology
ii. Haematology
iii. Biochemistry
samples taken for lab testing if infection is suspected - ANSWER:Urine
Wound swabs
Stool
Blood
Nose/Throat swab
Sputum
Pus
CSF
diagnostic workflow - ANSWER:-specimen collection
- specimen receipt
- specimen processing
- testing
- interpretation
- reporting
, Specimens must be collected and handled properly - ANSWER:Ø Should be taken
from the site of infection
Ø The sample must be taken aseptically
Ø Sufficient sample should be taken for the test requested
Ø The specimen must be stored and transported correctly
Common problems - ANSWER:ØWrong sample type provided
Ø Inappropriate storage or transport
Ø Sample contamination
Ø Insufficient sample provided
Ø Antibiotic therapy started before sampling
different test methods - ANSWER:- culture
- biochemistry
- microscopy
- antigen detection
- antibody detection
- mass-spectrometry
- molecular
microscopy - ANSWER:can be performed quickly and cheaply, and is relatively easy
to carryout
Gram stain - ANSWER:- determine whether a bacterium is gram-positive or gram-
negative
- can be performed directly on clinical specimens or on pure cultures of bacteria
results of gram stain - ANSWER:direct antibiotic therapy prior to a definitive
identification of the pathogen
acid fast stain - ANSWER:used to identify acid-fast bacteria
capsule staining - ANSWER:- negative stain with India ink
- Primarily used to detect Cryptococcus neoformans and other encapsulated fungi
Endoscope staining - ANSWER:Examples of bacteria that form endospores include
members of the genera Bacillus and Clostridium
culture - ANSWER:growth of organisms in the laboratory using either solid or liquid
media
growth of different bacteria in culture - ANSWER:ØAnaerobes and fastidious bacteria
can be slow growing (days to weeks)
Ø Mycobacteria grow very slowly
Ø Some organisms cannot be easily cultured (e.g. Treponema pallidum)
Ø Obligate intracellular bacteria (e.g. Chlamydia) need to be grown in cell culture
- most will grow overnight