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Y1 FHD > Bacteria, Fungi Viruses lecture > Flashcards

Bacteria, Fungi Viruses lecture Flashcards

1
Q

What does dipstick urinalysis look for (some examples)

A

Cells
RBCs
WBCs (leucocytes)
Bacteria, Fungi, Yeast, Parasites (Culture on agar +blood)

Glucose, Ketones, nitrates, crystals,

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2
Q

When culturing micro samples what medium should be used

A

Culture on agar: blood/chocolate/CLED)

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3
Q

How long does it take to find out specific pathogen by micro culture

A

24-48hrs
24 any info
48 specific info (antibiotic resistance/culture specificity)

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4
Q

3 types of AGAR +/- nutrient plates

A

blood (BAP, blood agar plate)
enriched, bacterial growth medium. Fastidious organisms, such as streptococci, do not grow well on ordinary growth media but grow on blood agar. … Blood agar consists of a base containing a protein source (e.g. Tryptones), soybean protein digest, sodium chloride (NaCl), agar, and 5% sheep blood

chocolate (CHOC/CBA chocolate agar plate)
variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C. Chocolate agar is used for growing fastidious respiratory bacteria

CLED (cystine–lactose–electrolyte-deficient agar)
It supports the growth of urinary pathogens and contaminants but prevents undue swarming of Proteus species due to its lack of electrolytes.

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5
Q

Things that can be added to agar (5 examples)

A 
Blood
Potato starch
Sugars / Salts
Antibiotics
pH indicators
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6
Q

What does CLED plate show

A

for urinary cultures
CLED agar produces a yellow colour if the bacteria ferments lactose to produce acid
- typical of E. coli and not some other urinary bacteria

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7
Q

What is measured on agar plate to show antibiotic resistance

A

antibiotic susceptibility via zones of inhibition

resistant vs sensitive

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8
Q

What are the benefits of diagnostic microbiology

A

Corrects your guesses
Allows you to focus your treatment
Informs the epidemiology

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9
Q

Laboratory Techniques used in diagnostic microbiology

A

Microscopy

Culture inc on Nutrient and selective agar plates

and for difficult-to-culture organisms;
Serological Techniques
Molecular Techniques (PCR)
Tissue culture

Staining

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10
Q

When might gram staining/microscopy not be useful?

A

Can be useful from ‘sterile sites’
Cerebrospinal fluid (CSF), joint fluid
In many cases NOT useful from ‘non-sterile’ sites
e.g. Sputum from a patient with a ? chest infection

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11
Q

What are the 5 basic shapes of bacteria

A 
spherical (cocci),
rod(bacilli),
spiral(spirilla), 
comma (vibrios) or 
corkscrew (spirochaetes).
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12
Q

what are the 6 shapes of spherical (cocci) bacteria

A

Micrococci

Diplococci

Streptococci

Staphylococci

Tetracocci

Sarcine

They can exist as single cells, in pairs, chains or clusters.

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13
Q

what are the 3 shapes of rod shaped (bacillus) bacteria

A

Bacillus

Steptobacillus

Coccobacillus

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14
Q

What is the best way to make the diagnosis of Pneumocystis jiroveci (carinii)pneumonia

A

to perform a Gomori methenaminesilver(GMS)stainon the lung tissue or bronchoalveolar lavage (BAL) fluid.

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15
Q

What is BAL fluid

A

BAL=bronchoalveolar lavage (saline flush of lungs during bronchoscopy)

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16
Q

What is GMS stain?

A

Grocott-Gomori methenamine silver (GMS) is a special stain to detect fungi - HIVE +ve/AIDS (susceptible to unusual pathogens)

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17
Q

What is a Zeihl Neelson Stain

A

Ziehl-Neelsen stainingis a type of acid-fast stain, mainly Mycobacteria

18
Q

What is Auramine phenol stain

A

Auramine phenol stain can identify tuberculosis mycobacteria

19
Q

Parasites - what is an example from lecture that can be visualised directly

A

Pinwormsare tiny, narrow worms. They’re white in colour and less than a half-inch long.

20
Q

How can you visualise viruses by microscopy?

A

can be seen by Electron microscopy

21
Q

What type of organism can be directly visualised

A

Parasites and ova (parasitic eggs) stool samples mainly

22
Q

Pros and cons of bacterial culture

A

Slow but provides a lot of information

Can quantify bacteria
Purification
Provisional identification
Antibiotic susceptibility testing by disc testing

Bacterial identification
Traditionally basis of bacterial metabolism

23
Q

What’s an API test

when is it used

A

API (analytical profile index) strips give accurate identifications based on extensive databases and are standardized, easy-to-use test systems.

use to sub classify gram -ve bacteria

24
Q

What technique is MALDI-TOF

A

Mass spectrometry is an analytical technique in which samples are ionized into charged molecules and ratio of their mass-to-charge can be measured. In MALDI-TOF mass spectrometry, the ion source is matrix-assisted laser desorption/ionization (MALDI), and the mass analyzer is time-of-flight (TOF) analyzer.

25
Q

Culture-based diagnostics: summary

A

Good for detecting bacteria you can stain and grow

Reliable identification and resistance testing

Very slow and labour intensive

26
Q

what is Serology (serum-ology)

A

Serology is the scientific study of serum and other body fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum. Such antibodies are typically formed in response to an infection, against other foreign proteins, or to one’s own proteins.

IgM Found mainly in blood and lymph fluid, this is the first antibody the body makes when it fights a new infection.
IgG This is the most common antibody. It’s in blood and other body fluids, and protects against bacterial and viral infections. IgG can take time to form after an infection or immunisation.

27
Q

what does IgM indicated in terms of infection

A

acute infection innate?

28
Q

what does IgG indicate in terms of infection

A

chronic adaptive response

29
Q

What viruses to consider in glandular fever

A

Epstein Barr Virus (EBV)

Cytomegalovirus (CMV)

30
Q

Symptoms of glandular fever

A

Fever
Sweats
Sore throat
Swollen lymph glands in her neck

31
Q

If person has specific IgG are they immune or susceptible to the pathogen?

A

IgG+ve = immunity (previous infection)

32
Q

If person has specific IgM to pathogen what does that indicate?

A

Active/acute infection

33
Q

PCR three steps

A

denature (92-95)
anneal primers (50-70 primer dependant)
extension of dsDNA (72 taq pol)

approx 30-35 cycles

34
Q

What is latency in infection

A

ability of infection to remain dormant for long periods of time before reactivation

e.g.

Chicken pox reactivating as Herpes zoster (shingles)
Cold sores (HSV)
CMV & EBV (subclinical unless immune suppressed)
Tuberculosis
Mechanisms and sites of latency poorly understood
Genetic material present but not causing disease

35
Q

When is Whole genome sequencing used on bacteria

A

Sequencing entire DNA of bacteria
Compare strains to see how related they are/evolve
Interrogate for antibiotic resistance genes
Set to revolutionise diagnosis of infection
Rapid (hours)
Cheap (comparable to culture)
Desktop Platforms

36
Q

When is PCR used?

A 
Viral encephalitis
Viral infection of brain tissue
Fever, headache, confusion, fits
Many causes
Enteroviruses most common
Herpes viruses (HSV, VZV, CMV, EBV)
PCR commonly used to diagnose viral encephalitis
Good negative predictive value
Poor positive predictive value so backed up by brain imaging, cells in spinal fluid
37
Q

What is HIV mainly diagnosed by

A

HIV mainly diagnosed by serology

PCR diagnosis in early HIV infection
To diagnose resistance
Monitoring response to treatment (’viral load’)

38
Q

what is tissue culture used for in diagnostic micro

A

Intracellular organisms
Viruses
Mycoplasma
Chlamydia

39
Q

how is tissue culture used for in diagnostic micro

A

Two main ways:
Cytopathic effects on cells
Expression of viral proteins detected at the cell surface

40
Q

What is rubella

A

Rubella(German measles) is a rare illness that causes a spotty rash. Serious in pregnant women.

41
Q

What is CPE

what lab test identifies this

A

Cytopathic effect(CPE), structuralchangesin a host cell resulting from viral infection. CPE occurs when the infecting virus causes lysis (dissolution) of the host cell or when the cell dies without lysis because of its inability to reproduce.
Tissue culture

42
Q

Immunofluoresence in micro

A

fluorescent ab/ag labelling of e.g.viral surface proteins

Y1 FHD (12 decks)

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