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Clinical Pathology Year 2 > Advanced Microbiology > Flashcards

Advanced Microbiology Flashcards

1
Q

(Antivirals) What are the 3 groups of Nucleoside Reserve Transcriptase Inhibitors (NRTI)?

A

1) AZT (azidothymide) = inhibits HIV replication
2) Zidovudine & Lamivudine = pyramidine analogues
3) Abacacir, Tenofovir = purine analogues

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2
Q

(Antivirals) What are 2 examples of Non-nucleotide Reverse Transcriptase Inhibitors (NNRTI)?

A

Efavirenz

Nevirapine

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3
Q

(Antivirals) What are 2 examples of Protease Inhibitors (PIs) and what are these used for?

A

a) Atazanine/ Darunavir/ Ritonavir = HIV (they all sound like names)
b) Paritaprevir/ Grazoprevir = HCV

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4
Q

(Important Antivirals) What is Aciclovir and what is it used for?

A

Aciclovir- Nucleoside analogue, Herpes Simplex virus (HSV) & Varicella Zoster Virus (VZV)

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5
Q

(Important Antivirals) What are the following used for?

a) Ganciclovir
b) Oseltamivir/ Zanamavir
c) Ribavirin
d) Interferons

A

a) Ganciclovir = Cytomegalovurus (CMV)
b) Oseltamivir/ Zanamavir = Influenza (neuraminidase inhibitor)
c) Ribavirin = RSV, HCV, HEV
d) Interferons = Hep B virus cure!

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6
Q

What does Highly Active Anti-Retroviral Therapy (HAART) consist of?

A

2xNRTIs & NNRTI

or 2xNRTIs & boosted PI

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7
Q

(Antibiotics) Give an example of a Glycopeptide (formulary B antibacterial NON beta-lactam)

A

Vancomycin, teicoplanin (can also give in penicillin allergy)

  • GRAM POSITIVE activity (staph, strep, enterococci)
  • Most gram negative are intrinsically resistant becuase their outer membranes are impermeable to to large glycopeptide molecules)
  • Treats meningitis caused by methicillin-resistant S. aureus
  • 1st line treatment for skin/ bloodstream infections, endocarditis.
  • Vancomycin has renal toxicity
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8
Q

(Antibiotics) What are the 4 Protein Synthesis Inhibitors?

A

a) Gentamicin/ amikacin (aminoglycosides)
b) Macrolides, Lincosamides, Streptogramins (MLS antibiotics)
c) Tetracyclines
d) Oxazolidinones

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9
Q

(Antibiotics) Give an example of an Aminoglycoside (Formulary B antibacterial NON beta-lactam, also a type of Protein Synthesis Inhibitor)

A

Gentamicin - binds to 30s ribosomal subunits

  • GRAM NEGATIVE BACILLI (including pseudomonas)
  • covers staphylococci, poor streptococcal (but synergism)
  • Can cause nethro/oto toxicity
  • IV/IM, topical
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10
Q

(Antibiotics) Give an example of a Macrolide (Formulary B antibacterial NON beta-lactam, also known as MLS antibiotics)
Give an example of a Lincosamide.

A

Macrolide- ery/clari/azi-thromycin

  • GRAM POSITIVE organisms (strep, staph)
  • limited gram negative cover (azithromycin will cover GN)
  • covers ATYPICAL organisms (intracellular), like for chlamydia, legionella

Lincosamide= Clindamycin (bind to 50s ribosomal subunit)

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11
Q

(Antibiotics) Give an example of a Tetracycline (a type of Protein Synthesis Inhibitor)

A

Tetracycline, doxycycline, tigecycline (broader spectrum)

  • Bind to 30s ribosomal subunit
  • inhibit translation by interfering with binding of tRNA to rRNA
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12
Q

(Antibiotics) Give an example of an Oxazolidinone (a type of Protein Synthesis Inhibitor)

A

Linezolid

  • Inhibits initiation of protein synthesis
  • Binds to 50s ribosomal subunits
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13
Q

(Antibiotics) What is Flucloxacillin used for?

A

MRSA (penicillinase-resistant penicillin)

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14
Q

(Antibiotics) What are the 2 types of DNA synthesis inhibitors?

A

a) Trimethoprim & Sulphonamide

b) Quinolones & Fluoroquinolones

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15
Q

(Antibiotics) How do Trimethoprim & Sulphonamide work? (DNA synthesis inhibitors)

A

They both inhibit folate synthesis- a precursor for Purine synthesis.
Trimethoprim- commonly treats UTIs
Trimethoprim + Sulphonamide- combination used in treatment for some protozoal infections & resistant bacterial infections.

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16
Q

(Antibiotics) How do Quinolones & Fluoroquinolones work? (DNA synthesis inhibitors, and Formulary B antibacterial NON beta-lactams)

A

Quinolones- eg) Ciprofloxacin, levofloxacin. (inhibit DNA gyrase and topoisomerase IV) (Effective against bacteria only)
Fluoroquinolone-
a)CIPROFLOXACIN (early): GRAM NEGATIVEs, staphylococcal/ ‘atypicals’. Poor streptococcal/anaerobic activity
b) LEVOFLOXACIN (late): GRAM POSITIVEs, streptococci, ‘resp FQ’ as cover resp tract infections.

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17
Q

(Antibiotics) Give an example of a RNA Synthesis Inhibitor.

A

Rifampicin: RNA polymerase inhibitor, prevents mRNA synthesis (cornerstone of anti-TB chemotherapy)

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18
Q

Give 2 examples of Antibacterial Cell Membrane Agents?

A

Colistin (GRAM NEGATIVES)

Daptomycin (GRAM POSITIVES)

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19
Q

Give 3 examples of Antifungal Cell Membrane Agents?

A

1) Azoles (clotrimazole, fluconazole)
2)Terbinafine
3) Amphotericin B
(2&3 are to do with ergosterol, a component of fungal cell walls)

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20
Q

What is an Antifungal agent?

A

Echocandins eg)Anidulafungin, Caspofungin, Micafungin.

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21
Q

What is Clindamycin used for? (example of Forulary B antibacterial NON beta-lactam)

A
  • GRAM POSITIVE organisms (staph, strep), anaerobes
  • Anti-toxin action
  • Highly associated with C diff infection
  • ORAL/IV
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22
Q

What is Metronizadole used for? (example of Forulary B antibacterial NON beta-lactam)

A
  • Bacteria, anaerobes

- Parasites! (protozoa, helminths)

23
Q

What are the 3 Formulary B antibacterials beta-lactams?

A

1) Penicillins: benzylpenicillin, flucloxacillin, amoxicillin
2) Beta-lactam/ Beta-lactamase inhibitor combinations: coamoxiclav, tazocin
3) Cephalosporins: cephalexin, cefuroxime, cefotaxime.

24
Q

Give 3 examples of Beta-lactamase enzymes (enzymes that hydrolyze beta-lactams, resulting in resistance to beta-lactam antibiotics)

A

1) Staphylococcal beta-lactamase = resistant to some penicillins
2) ‘Extended Spectrum Beta-lactamase’ (ESBL) = resistant to penicillins & cephalosporins
3) Carbapenemases (eg NDM1) = carbapenems

25
Q

What are Beta-lactam/ Beta-lactamase inhibitor combinations (BLBLI) and give 2 examples of these?

A

V broad spectrum, predispose to C dif. (dont end in -illin, so penicillin allergy may be missed)

a) Augmentin- increases the spectrum of amoxicillin
b) Tazocin- increases the spectrum of piperacillin

26
Q

What are 5 examples of Formulary B antibacterials NON beta-lactams?

A 
1- Aminoglycosides (gentamicin)
2- Macrolides (ery/clari/azi-thromycin)
3- Glycopeptides (vancomycin)
4- Quinolones (ciprofloxacin & levofloxacin)
5- Tetracyclines (doxycycline)
27
Q

What is Leucocyte Esterase an indicator of?

A

Enzyme produced by neutrophils.

Positive in: Chlamydia, urethritis, TB, bladder tumours, nephrolithiasis, corticosteroid use.

28
Q

What are Nitrites an indicator of?

A

Some bacteria reduce urinary nitrates to nitrites.

Positive nitrites: infection, but negative nitrite test doesn’t rule out UTI.

29
Q

(Formulary B antibacterials Beta-lactams) Give a general description of Penicillins, and what are 4 types?

A 
Bacericidal
Cross reaction with other beta-lactams (cephalosporins, carbapenems)
1- Penicillin G & V
2- Flucloxicillin
3- Amoxicillin
4- Tazocin
30
Q

What are Penicillin G and Penicillin V?

What are they used for?

A

-Penicillin G (benzylpenicillin, IV/IM)
-Penicillin V (phenoxymethylpenicillin, ORAL)
Both are narrow spectrum, destroyed by beta-lactamases.
Best used for= Streptococci (S pneumoniae, S pyogenes)
= also covers anaerobes
=covers some GNC (N meningitidis, N gonorrhoeae)

31
Q

What is Flucloxicillin and what is it used for?

A

(spectrum broader than Penicillin G) (not destroyed by staphylococcal beta-lactamase)
Used for= Staphylococci (not MRSA)
=many anaerobes, most streptococci

32
Q

What is Amoxicillin and what is it used for?

A

(spectrum broader than Penicillin G) (destroyed by staphylococcal beta-lactamase)
Used for= streptococci, enterococci, some GNB

33
Q

What is Tazocin and what is it used for?

A

(step up from amoxycillin, will cover more GNB)
Anti-pseudomonal activity
Broad spectrum= staphylococci (not MRSA), streptococci, enterococci, anaerobes, pseudomonas, GNB & GNC.
Doesnt cross BBB

34
Q

What is ‘sensitivity testing’?

A

Culture micro-organisms in the presence of antimicrobial agent.
Determine whether minimum inhibitory concentration (MIC) is above ‘breakpoint’ level.

35
Q

What are some clinical consequences of antibiotic resistance?

A

1- Meticillin-resistant Staphylococcus aureus (MRSA)
2- Vancomycin/ glycopeptide resistant enterococci (VRE/GRE)
3- Enterobacteriaceae resistant to many things, such as carbapenems, beta-lactams (amoxicillin, gentamicin) etc

36
Q

Examples of Live Immunisations in active immunity?

A

MMR, BCG, Yellow Fever, Varicella

37
Q

Examples of inactivated organisms in active immunity vaccine?

A

Pertussis, typhoid, IPV

38
Q

Examples of inactivated toxins in active immunity vaccine?

A

Diptheria, tetanus

39
Q

Difference between primary and secondary immune response?

A

Primary Immune Response: develops in weeks following first exposure- mainly IgM antibody
Secondary Immune Response: is faster & more powerful- mainly IgG antibody

40
Q

Describe briefly how antibodies produce immunity.

A
  1. Antibodies produced from B lymphocytes
  2. Antigen binds to variable region of antibody (Ig)- triggers CLONAL EXPANSION
  3. IgM production, followed by IgG
  4. IgG binds tightly to antigen, simultaneous complementary binding facilitates the destruction of the antigen-bearing microorganisms
  5. Infection resolves, IgG decline
  6. Immunological memory from some remaining IgG producing B lymphocytes
41
Q

What is the susceptible population?

A

The number of secondary cases caused by each infectious person.

42
Q

Why would a white blood cell count be useful in an infection test?

A

Can be raised in infection, but poor specificity (sepsis can lower WCC)
Neutrophils typically raised in bacterial infection
Lymphocytes typically raised in viral infection

43
Q

What is Seroconversion?

A

Change from negative to positive result from one test to a subsequent test

44
Q

What are 4 methods of sterilisation?

A

1) HEAT (moist= autoclave) (dry= oven)
2) CHEMICAL
3) FILTRATION
4) IONISING RADIATION (used for single use disposable equipment)

45
Q

What is antisepsis?

A

This is disinfectant applied to damaged skin or living tissue, needs to be minimal toxicity.

46
Q

What are the 3 methods of DECONTAMINATION?

A

1- STERILISE (destroys all microorganisms including spores. For all reusable surgical equipment)
2- DISINFECT (reduces microorganisms to a level that is nolonger harmful. For items that will contact mucous membranes or contaminated with bodily fluids)
3- CLEAN (removal of dirt/ organic matter using water and detergent. For items that only contact intact skin)

47
Q

What level of decontamination for…

a) syringe needle
b) flexible endoscope
c) central venous catheter insertion site
d) surgical instrument reprocessing
e) surgeon’s hands

A

a) Sterilisation (disposal after use)
b) High level disinfectant
c) Disinfection (antisepsis)
d) Sterilisation
e) Washing

48
Q

What is Encephalitis caused by?

A 
Usually viral (Herpes virus)
(it is inflammation of the brain)
49
Q

What are Rhino-sinusitis (sinusitis) and sore throats (pharyngitis) usually caused by?

A

Majority are viral.

Secondary bacterial infections (end throat swabs only if evidence of bacterial)

50
Q

What are some pathogens that cause Diarrhoea?

A

Viruses: norovirus, rotavirus
Bacteria: Salmonella, Shigella, E Coli
Parasites: Cryptospordium, Giardia
C dif infection

51
Q

What are the 4 tests for H pylori?

A 
H Pylori antibody test
H Pylori stool antigen
Urea breath test
Biopsy urease test
STOP PPIs before testing
52
Q

How do you diagnose Endocarditis?

A

Three sets of blood cultures should be taken at different times during the first 24hours (same with Vascular Graft Infections)

53
Q

What are viral Hepatitis (Hep A,B&C) investivations based on?

A

Based on Serology

Serology comprises Antigen & Antibody detection

54
Q

What spikes in Hep C infection? (looking at serology)

A

Alanine Transaminase

Clinical Pathology Year 2 (11 decks)

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