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Z Medicine Term 1 > microorganisms and antimicrobial chemotherapy > Flashcards

microorganisms and antimicrobial chemotherapy Flashcards

1
Q

gram positive cocci

A

staphylococci (clusters) streptococci (chains)

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2
Q

staphylococci coagulase test

A

+ = staph. aureus - = staph. epidermis or saprophyticus

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3
Q

streptococci haemolysis

A

partial (a) turns green = pneumoniae, vidrians complete (b) turns clear = pyogenes non-haemolytic = enterococci

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4
Q

gram positive aerobic bacilli

A

non-spore forming = listeria monocytogenes, corynebacterium diptheriae spore forming = bacillus species

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5
Q

gram positive anaerobic bacilli

A

all spore forming = clostridium species

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6
Q

gram negative cocci

A

moraxella catarrhalis neisseria gonorrhoeae/meningitidis

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7
Q

gram negative anaerobic bacilli

(that grow on MacConkey’s)

A

almost all are coliforms

lactose fermenters: (agar goes pink)

escherichia coli

klebsiella sp.

lactose non-fermenters: (agar stays clear)

proteus sp.

shigella sp.

salmonella sp.

pseudomonas sp. (not a coliform)

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8
Q

Gram negative anaerobic bacilli

(that don’t grow on MacConkney’s)

A

bacteroides sp.

prevotella sp.

porphyromonas sp.

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9
Q

gram negative curved bacilli

(seagul shaped)

A

campylobacter sp.

vibrio sp.

helicobacter sp.

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10
Q

gram negative cocco-bacilli

A

haemophilus influenzae

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11
Q

acid and alcohol fast bacteria (AAFB)

(gram stain not applicable)

A

mycobacterium tuberculosis

atypical mycobacteria

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12
Q

spirochaetes

A

treponema sp

borelia sp.

leptospira sp.

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13
Q

miscelaneous organisms

A

chlamydia sp.

Rickettsia ap.

Coxiella Burnetii

Mycoplasma sp.

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14
Q

Benzyl Penicillin/penicillin G (penicillin, β-lactam)

A

Administration: Intravenous (phenoxymethylpenicillin is a derivative with better oral absorption)

Spectrum: gram positives and meningococci

Mechanism: disrupts peptidoglycan synthesis

Toxicity: can cause allergic reactions

Resistance: resisted by β-lactamase producing bacteria (e.g. staph. aureus) and bacteria that alter the structure of their PBPs (e.g. MRSA)

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15
Q

Amoxicillin/Ampicillin (penicillin, β-lactam)

A

Administration: oral

Spectrum: gram positives and some coliforms

Mechanism: disrupts peptidoglycan synthesis

Toxicity: can cause allergic reactions

Resistance: resisted by β-lactamase producing bacteria (e.g. staph. aureus) and bacteria that alter the structure of their PBPs (e.g. MRSA)

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16
Q

Co-amoxiclav (penicillin, β-lactam)

amoxicillin combined with clavulanic acid (a β-lactamase inhibitor)

A

Spectrum: gram positives and β-lactamase producing coliforms

Mechanism: disrupts peptidoglycan synthesis

Toxicity: can cause allergic reactions

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17
Q

Flucloxacillin (penicillin, β-lactam)

represented by methicillin in lab testing

A

Spectrum: gram positives including staphylococci that produce β-lactamase

Mechanism: disrupts peptidoglycan synthesis

Toxicity: can cause allergic reactions, associate with hepatotoxicity

Resistance: side chain is modified to be resistant to β-lactamase but resisted by MRSA

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18
Q

Piperacillin (penicillin, β-lactam)

A

Spectrum: extended gram-negative cover compared to other penicillins, including enterococcus faecalis and pseudomonas. Anti-aerobic activity (so covers intra-abdominal infection)

Mechanism: disrupts peptidoglycan synthesis

Toxicity: can cause allergic reactions

Resistance: commonly used with tazobactam (a β-lactamase inhibitor) to make tazocin, known as “pip/taz”

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19
Q

Carbapenems (β-lactam)

e.g. imipenem, meropenem

A

Spectrum: widest spectrum of all antibiotics, including anaerobes

Mechanism: inhibition of cell wall synthesis

Toxicity: can cause allergic reactions

Resistance: resisted by carbepenemase producing enterobacteriaceae (CPE)

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20
Q

Cephalosporins (β-lactam)

A

Spectrum: gram-negative activity increases from 1st– 3rd generation, gram-positive activity decreases from 1st – 3rd generation. Only ceftazidime (3rd gen) has activity against pseudomonas.

Mechanism: disrupts peptidoglycan synthesis

Toxicity: can cause allergic reactions, encourages clostridium difficile infection

Resistance: 3rd gen broken down by extended spectrum β-lactamases (ESBL)

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21
Q

Glycopeptides

e.g. vancomycin, teicoplanin

A

Administration: parenteral (can’t be absorbed from GI tract – given orally only to treat clostridium difficile infection)

Spectrum: aerobic and anaerobic gram-positives only (can’t penetrate gram-negative cell wall)

Mechanism: inhibit assembly of a peptidoglycan precursor

Toxicity: Toxicity: renal toxicity (nephrotoxicity), hearing and balance (ototoxicity). Serum levels must be monitored carefully.

Resistance: resisted by vancomycin resistant enterococci (VRE) – the peptidoglycan precursor that vancomycin binds to has an altered structure

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22
Q

Aminoglycosides

e.g. gentamicin

A

Administration: parenteral only

Spectrum: gram-negatives including pseudomonas and staphylococci

Mechanism: blocks translation at the ribosome

Toxicity: renal toxicity (nephrotoxicity), hearing and balance (ototoxicity). Serum levels must be monitored carefully.

Resistance: very little

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23
Q

Macrolides(bacteriostatic) – used in patients with penicillin allergy

e.g. clarithromycin, erythromycin, azithromycin

A

Spectrum: gram-positives and organisms causing atypical pneumonia. Azithromycin used for chlamydia

Mechanism: stops protein elongation at the ribosome

Resistance: resisted by ~10% staph. aureus, strep. pyogenes and strep. pneumonae. So sensitivity testing needed

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24
Q

Tetracyclines (bacteriostatic)

A

Spectrum: broad spectrum but rarely used

Mechanism: stop translation by binding to RNA at the ribosome

Toxicity: deposited in teeth and bone so not for children or pregnant women, liver toxicity

25
Oxazolidinones e.g. Linezolid
Administration: oral Spectrum: includes MRSA so reserved for serious infections Mechanism: disrupts ribosome structure Toxicity: bone marrow suppression, lowers platelet count
26
Cyclic Lipopeptide e.g. Daptomycin
Spectrum: Gram positives including MRSA so reserved for serious infections Mechanism: inhibition of protein synthesis
27
Trimethoprim and Sulphamethoxazole (combined = co-trimoxazole) Trimethoprim = bacteriostatic
Administration: oral and parenteral Spectrum: trimethoprim used for urinary infections. Co-trimoxazole used for chest infections as it doesn’t lead to c. difficile infections Mechanism: inhibit purine synthesis by competitive inhibition of folic acid synthesis Toxicity: folate deficiency in host cells may lead to megaloblastic anaemia
28
(Fluoro)quinones e.g. ciprofloxacin, levofloxacin
Administration: oral and parenteral Spectrum: gram-negatives including pseudomonas, newer generations have activity against some gram positives and are sometimes used against pneumococci Mechanism: directly inhibit DNA synthesis Toxicity: interferes with cartilage growth so cannot be used in children
29
Metronidazole
Administration: oral to treat c. difficile infection Spectrum: gram-positive and negative anaerobes Mechanism: inhibition of nucleic acid synthesis Toxicity: peripheral neuropathy Resistance: virtually none
30
Fusidic Acid
Administration: (diffuses well into bone and tissue) Spectrum: staphylococcus Mechanism: inhibition of protein synthesis Resistance: resistance readily developed by staph. aureus so always used in combination with flucloxacillin etc.
31
Clindamycin
Administration: oral (good tissue penetration) Spectrum: gram-positives and anaerobes Mechanism: inhibition of protein synthesis Toxicity: commonly causes pseudo-membranous colitis (caused by c.difficile)
32
Fidaxomicin
Spectrum: narrow spectrum, includes clostridium difficile Mechanism: inhibition of nucleic acid synthesis
33
Nalidixic Acid
Spectrum: gram-negative anaerobes (coliforms). Completely excreted in urine so only used for coliform urinary tract infections Mechanism: inhibition of nucleic acid synthesis
34
Nitrofurantoin
Spectrum: gram negatives (NOT proteus and pseudomonas), and some gram positives. Only used in urinary tract infections Mechanism: inhibition of protein synthesis Toxicity: peripheral neuropathy
35
nucleoside analogue
interferes with nucleic acis synthesis
36
HSV
herpes simplex virus
37
VZV
varicella-zoster virus | (chicken pox)
38
Aciclovir
Administration: IV for severe infections. Oral/topical for coldsores Spectrum: Herpes simplex virus (HSV) and varicella zoster virus (VZV) (chicken pox) Mechanism: nucleoside analogue Toxicity: very low unless there is renal impairment
39
Famciclovir + valaciclovir
Administration: oral Spectrum: HSV and shingles Mechanism: nucleoside analogue Toxicity: very low unless there is renal impairment
40
Ganciclovir
Administration: IV Spectrum: CMV (cytomegalovirus) – type of herpes Mechanism: nucleoside analogue Toxicity: bone marrow toxicity so blood count monitoring needed
41
Valgaciclovir
Administration: Oral Spectrum: CMV (cytomegalovirus) – type of herpes Mechanism: nucleoside analogue Toxicity: bone marrow toxicity so blood count monitoring needed
42
Foscarnet
Administration: IV Spectrum: HSV, VZV, CMV Toxicity: highly nephrotoxic
43
Cidofovir
Spectrum: CMV retinitis
44
Zidovudine
Spectrum: HIV Mechanism: nucleoside analogue that interferes with reverse transcriptase Toxicity: high incidence of anaemia and neutropenia (low neutrophil conc.)
45
Nevipapine + Efavirenz
Spectrum: HIV Mechanism: reverse transcriptase inhibitor Toxicity: significant toxicity
46
Saquinavir + Darunavir
Spectrum: HIV Mechanism: inhibits viral protease enzymes Toxicity: significant toxicity
47
Lamidivine
Spectrum: HIV
48
Interferon α
Administration: subcutaneous injection Spectrum: Hep B + C Mechanism: genetically engineered host immune response
49
Tenofovin
Administration: Oral Spectrum: Hep B
50
Zanamavir + Oseltamivir
Spectrum: Influenza A + B
51
Ribavarin
Administration: inhaled as a spray Spectrum: respiratory syncytial virus (RSV) Mechanism: nucleoside analogue
52
filamentous fungi
moulds
53
Dermatophytes
fungi which grow on the skin surface
54
Polyenes Amphotericin B, Nystatin
Administration: Amphotericin B – IV for serious infections. Nystatin – oral and topical Spectrum: yeasts and filamentous fungi Mechanism: binds to ergosterol in the fungal cell wall, increasing its permeability Toxicity: also binds to other sterols in mammalian cell walls so toxic. Amphotericin B causes renal, hepatic and cardiac toxicity
55
Azoles Imidazole, Triazoles (fluconazole), itraconazole
Administration: fluconazole – oral and parenteral Spectrum: fluconazole - yeasts. Itraconazole – yeasts and moulds Mechanism: inhibits ergosterol synthesis Resistance: emerging among some candida species. Found in c. krusei and c.glabrata in immunosuppressed patients
56
Allylamines terbinafine
Administration: topical (sometimes oral) Spectrum: dermatophytes (e.g. athlete’s foot) Mechanism: supresses ergosterol synthesis
57
Echinocandins Caspofungin, mycafungin, anidulafungin (only for serious infections)
Spectrum: fungicidal against candida. Fungistatic against some aspergillus sp. Mechanism: inhibits glucan polysaccharide synthesis
58

Z Medicine Term 1 (8 decks)

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