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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
Q

Oxazolidinones

e.g. Linezolid

A

Administration: oral

Spectrum: includes MRSA so reserved for serious infections

Mechanism: disrupts ribosome structure

Toxicity: bone marrow suppression, lowers platelet count

26
Q

Cyclic Lipopeptide

e.g. Daptomycin

A

Spectrum: Gram positives including MRSA so reserved for serious infections

Mechanism: inhibition of protein synthesis

27
Q

Trimethoprim and Sulphamethoxazole (combined = co-trimoxazole)

Trimethoprim = bacteriostatic

A

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
Q

(Fluoro)quinones

e.g. ciprofloxacin, levofloxacin

A

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
Q

Metronidazole

A

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
Q

Fusidic Acid

A

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
Q

Clindamycin

A

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
Q

Fidaxomicin

A

Spectrum: narrow spectrum, includes clostridium difficile

Mechanism: inhibition of nucleic acid synthesis

33
Q

Nalidixic Acid

A

Spectrum: gram-negative anaerobes (coliforms). Completely excreted in urine so only used for coliform urinary tract infections

Mechanism: inhibition of nucleic acid synthesis

34
Q

Nitrofurantoin

A

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
Q

nucleoside analogue

A

interferes with nucleic acis synthesis

36
Q

HSV

A

herpes simplex virus

37
Q

VZV

A

varicella-zoster virus

(chicken pox)

38
Q

Aciclovir

A

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
Q

Famciclovir + valaciclovir

A

Administration: oral

Spectrum: HSV and shingles

Mechanism: nucleoside analogue

Toxicity: very low unless there is renal impairment

40
Q

Ganciclovir

A

Administration: IV

Spectrum: CMV (cytomegalovirus) – type of herpes

Mechanism: nucleoside analogue

Toxicity: bone marrow toxicity so blood count monitoring needed

41
Q

Valgaciclovir

A

Administration: Oral

Spectrum: CMV (cytomegalovirus) – type of herpes

Mechanism: nucleoside analogue

Toxicity: bone marrow toxicity so blood count monitoring needed

42
Q

Foscarnet

A

Administration: IV

Spectrum: HSV, VZV, CMV

Toxicity: highly nephrotoxic

43
Q

Cidofovir

A

Spectrum: CMV retinitis

44
Q

Zidovudine

A

Spectrum: HIV

Mechanism: nucleoside analogue that interferes with reverse transcriptase

Toxicity: high incidence of anaemia and neutropenia (low neutrophil conc.)

45
Q

Nevipapine + Efavirenz

A

Spectrum: HIV

Mechanism: reverse transcriptase inhibitor

Toxicity: significant toxicity

46
Q

Saquinavir + Darunavir

A

Spectrum: HIV

Mechanism: inhibits viral protease enzymes

Toxicity: significant toxicity

47
Q

Lamidivine

A

Spectrum: HIV

48
Q

Interferon α

A

Administration: subcutaneous injection

Spectrum: Hep B + C

Mechanism: genetically engineered host immune response

49
Q

Tenofovin

A

Administration: Oral

Spectrum: Hep B

50
Q

Zanamavir + Oseltamivir

A

Spectrum: Influenza A + B

51
Q

Ribavarin

A

Administration: inhaled as a spray

Spectrum: respiratory syncytial virus (RSV)

Mechanism: nucleoside analogue

52
Q

filamentous fungi

A

moulds

53
Q

Dermatophytes

A

fungi which grow on the skin surface

54
Q

Polyenes

Amphotericin B, Nystatin

A

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
Q

Azoles

Imidazole, Triazoles (fluconazole), itraconazole

A

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
Q

Allylamines

terbinafine

A

Administration: topical (sometimes oral)

Spectrum: dermatophytes (e.g. athlete’s foot)

Mechanism: supresses ergosterol synthesis

57
Q

Echinocandins

Caspofungin, mycafungin, anidulafungin (only for serious infections)

A

Spectrum: fungicidal against candida. Fungistatic against some aspergillus sp.

Mechanism: inhibits glucan polysaccharide synthesis

58
Q
A

Z Medicine Term 1 (8 decks)

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