Role of Microbiology Lab Flashcards

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1
Q

What are the two important functions of microbiology labs?

A

Clinical- diagnosis of infection in an individual patient for everyday management of infections

Epidemiological- support for infection prevention and control in searching for source and route of transmission of HAI.

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2
Q

What are the 6 minimal requirements for microbiology services?

A

1- set up inside the facility (if not possible, negotiate a contract for diagnostic microbiology with the nearest lab)

2- available every day including Sundays and holidays (ideally on a 24 hour basis)

3- able to examine blood, CSF, urine, stool, wound exudate or swab, respiratory secretions, and perform basic seriological tests (HIV, HBV and HCV)

4- identify common bacteria and fungi to species level

5- perform susceptibility testing using disc-diffusion methodology

6- perform basic phenotyping (serotyping and biotyping).

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3
Q

What species can you serotype for?

A

Salmonellae, Shigellae, P. aeruginosa, N. meningitidis.

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4
Q

What species can you biotype for?

A

S. typhi.

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5
Q

What is the zone of inhibition?

A

The Zone of inhibition is a circular area around the spot of the antibiotic in which the bacteria colonies do not grow. … The zone of inhibition can be used to measure the susceptibility of the bacteria to wards the antibiotic.

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6
Q

What are the 3 classical bacteriological methods?

A

Direct smear
Culture
Antigen detection.

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7
Q

What are the 4 roles of diagnosing infection?

A

Classical bacteriological methods
Sensitivity testing
Antibody detection
Molecular methods.

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8
Q

What is a positive and negative of antibody testing?

A

Not very useful in the early stages of infection

It is good at deciding what type of organism is present.

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9
Q

What is the simplified scheme for bacterial identification?

A

Specimen…Direct examination…Culture…Pure culture and identification to species…Species name established…Typing or fingerprinting for taxonomic or epidemiological purposes.

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10
Q

What are the 4 different types of cocci?

A

Single coccus
Pair of cocci
Cluster of cocci
Chains of cocci.

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11
Q

What are the different types of rods?

A

Single rod
Chain of rods
Curved rod
Spiral.

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12
Q

What is the shape of strep mutans?

A

Chains of cocci.

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13
Q

Do gram negative or gram positive bacteria have a thick peptidoglycan cell wall?

A

Gram positive.

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14
Q

What are the six stages of the gram stain?

A

1- prepare a heat fixed film of bacteria on a glass slide
2- stain with crystal violet for one minute and rinse with water
3- treat with Gram’s iodine for one minute and rinse with water
4- briefly decolourise with acetone or ethanol (a few seconds depending on thickness of film)
5- counter stain with basic fuchsin or safranin (pink dye) for one minute and rinse with water
6- blot dry and view under oil immersion.

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15
Q

What does gram staining tell us?

A

Cell wall composition.

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16
Q

What are the four roles in prevention and control of HAI’s?

A

1- outbreak investigation
2- surveillance of HAIs
3- alert microorganisms reports
4- designing antibiotic policy.

17
Q

What are the two main aims of an outbreak investigation?

A

To determine the cause of a single-source outbreak the causative agent must be defined
Then microbiology laboratory determines if two or more isolated strains are same of different.

18
Q

What microbiological tests may be added during an outbreak?

A
Blood products
Environmental surfaces
Disinfectants and antiseptics
Air
Water
Hands of personnel
Anterior nares of personnel.
19
Q

What happens during HAI surveillance?

A

The microbiology lab should produce routine reports of bacterial isolates
A baseline incidence can be established
If the lab is computerised, these data can be made readily available.

20
Q

REMEMBER TO RESERVE ANTIBIOTICS ONLY IF PATHOGEN IS RESISTANT TO FIRST LINE ANTIBIOTICS!

A

.

21
Q

What is the role of clinical microbiologist/ID specialist?

A

Provide leadership to antimicrobial team
Antibiotic ward rounds
Interpretation of patient specific data to optimise treatment
Active surveillance/awareness (screening for carriage of resistant bacteria and molecular detection and typing).

22
Q

What are the chain of infection steps?

A
Infectious agent
Reservoir
Portal of exit
Mode of transmission
Portal of entry
Susceptible host.
23
Q

Remember: the lab should perform basic typing of microorganisms, should produce routine reports for IP&C personnel, they should interpret microbiological findings for IP&C personnel and act together with clinical and nursing colleagues in prevention of HAI.

A

.

24
Q

What are the four types of media?

A

Enrichment
Selective
Solid
Liquid.

25
Q

What are examples of molecular techniques?

A

DNA hybridisation

Nucleic acid amplification testing (PCR, LCR, real time PCr and automated DNA amplification).

26
Q

What are some examples of typing methods?

A
Phage
Serology
Bacteriocin
Endonuclease digestion
Multiocus sequence typing
Whole genome sequence.
27
Q

What are some examples of serological techniques?

A
Agglutination
Precipitation
Complement fixation
Virus neutralisation
ELISA
Radioimmunoassay
Immunofluorescence.
28
Q

Where do scientists get infectious disease morbidity and mortality data come from?

A
Statutory notification
Microbiology lab reports
Death certificate
GP surveillance schemes
Hospital infection reports
Specific reporting schemes.
29
Q

How can you break the chain of infection?

A
Contact tracing
Isolation
Early treatment
Vaccination
Antibiotic prophylaxis (e.g. meningitis
First aid
Handwashing
Treatment of underlying disease
Education
Sanitisation/disinfection.
30
Q

What are some solutions to break the chain of infection to apply in a hospital?

A
Ward design
Isolation facilities
Maintenance of air-conditioning and ventilation
Hospital design
Adequate space
Isolation facilities
Infection control policies
Staff education
Good clinical practice
Sterile supplies
Disinfection policy
Equipment sterilisation
Single-use items.