Overview Of Antimicrobials Flashcards by Iseoluwa Ojo | Brainscape

Q

Antimicrobials

Agents useful in treatment of infections by _______

A

microbes

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Q

Antibiotics are _______ which ________ or ______

A

substances got from a microorganism

suppresses the growth of another organism or eradicates another organism

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Q

Mechanism of action of penicillin

A

inhibit synthesisb of bacterial cell wall

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Q

Mechanism of action of cephalosporines

A

inhibit synthesisb of bacterial cell wall

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Q

Mechanism of action of cycloserine

A

inhibit synthesisb of bacterial cell wall

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Q

Mechanism of action of vancomycin

A

inhibit synthesisb of bacterial cell wall

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Q

Mechanism of action of bacitracin

A

inhibit synthesisb of bacterial cell wall

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Q

Mechanism of action of asole antifungals

A

inhibit synthesisb of bacterial cell wall

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Q

Mechanism of action of polymyxin

A

Fucks up bacterial cell membrane by increasing its permeability

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Q

Mechanism of action of polyene anti fungal nystatin

A

Fucks up bacterial cell membrane by increasing its permeability

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Q

Agents that affect function of 30S or 50s ribosomal subunit to cause (reversible or irreversible ?) inhibition of protein synthesis; these are bacterio___

A

Reversible

static

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Q

agents that affect bacterial nucleic acid metabolism, such as ______ e.g. rifampin which inhibit _____ and the _____ which inhibit ________________

A

rifamycins

RNA polymerase

quinolones

topoisomerase and DNA gyrase

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Q

the antimetabolites which block essential enzymes of folate metabolism such as ———- and the _______

A

trimethoprine

sulphonamides

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Q

antivirals: several classes exist.

a) nucleic acid analogues- ______ or ____ that selectively inhibit viral _______, and ______ or ______ , which inhibit ________

A

acyclovir; ganciclovir; DNA polymerase

zidovudine or lamivudine; reverse transcriptase

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Q

antivirals: several classes exist.

b) Nonnucleoside reverse transcriptase inhibitors, such as _______,_______
© inhibitors of HIV _______ or influenza ________

A

nevirapine, efavirence

protease; nuraminidase

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Q

Bacteriocidal agent: it _______________

A

kills the bacteria

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Q

Bacteriostatic agent: it _______________ so that the __________________

A

supresses the growth or replication of the bacteria

patient’s immune system eliminates it.

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Q

FACTORS THAT DETERMINE SUCEPTIBILITY TO ANTIMICROBIAL THERAPY
____________, as even bacteriocidal drugs will only _________ and the __________ will then _________

A

Intact host immune system

eliminate some bacteria

host’s immunity

eliminate the rest.

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Q

Hence when patient’s immune system is low, there is need for _______ or ______

A

more potent antibacterial or greater dose

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Q

High protein conc at the site (Pus)

May aid or limit drug action ?

A

Limit

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Q

High pH may limit drug action.

T/F

A

F

Low PH

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Q

Location of infection may limit drug action

T/F

A

T

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Q

BACTERIAL RESISTANCE TO ANTIMICROBIAL AGENTS
It can be ________ or _______

Common mechanisms is by _______,________,_________, or _______

A

primary or secondary

mutation, transduction, transformation, conjugation

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Q

______________________(m/c/s) is the ideal method of selecting antibacterials, this is combined with __________

However,

________ choice may be necessary :

A

MICROSCOPY, CULTURE AND SENSITIVITY

clinical impression

Empherical

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Q

Empherical choice may be necessary to prevent drug resistance

T/F

A

T

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Q

When could Empherical choice be necessary despite the m/c/s?

A

In serious infections

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Q

Complications Of combination OF Anti microbial agents includes superinfection

T/F

A

T

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Q

ANTI-TB drugs

_______________ is the causative organism

A

Mycobacterium tuberculosisis

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Q

ANTI-TB drugs

Drugs: 1st line drugs below have ______ level of efficiency with _______ degree of toxicity. _____ of them are combined

List them

A

greatest; an acceptable

Four

Isoniazid, rifampin, ethambutol, streptomycin or pyrazinamide.

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Q

ANTI-TB drugs

2nd line drugs can be used if there is _________ to first line drugs or _________

– list them

A

microbial resistance

patient related factors(unacceptable ADRs)

Capreomycin
Cycloserine
Amikacin
Aminosalucyclic acid
Kanamycin
Ethionamide

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Q

_________ is the primary antiTB Drug

A

Isoniazid

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Q

ISONIAZID
all patients with dx caused by isoniazid- sensitive strains of the _____ bacillus should receive the drug if they can tolerate it

A

tubercle

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Q

Isoniazid is related to _______, it is a ______ derivative.

A

nicotinamide

pyridine

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Q

Isoniazid

It is bacteriostatic for ______ but bactericidal for __________

A

resting bacilli

rapidly dividing micro- organisms.

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Q

Isoniazid

If ___________ is not given along with isoniazid ,___________ may occur.

A

pyridoxine (vitamin B6)

Peripheral neuritis

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Q

Which ANTI TB drug colors the urine orange

A

Rifampin

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Q

Rifampin:
This drug colours urine _______

Untoward effect- Not common. Rashes, fever, nausea, vomiting, _____ is most notable, _______ is not common.

A

orange

Jandice

Hepatitis

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Q

Ethanbutol: The most important reaction is ________ with decrease in ______ and inability to differentiate colour ——- from ______

A

optic neuritis

visual acuity

red from green.

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Q

Adverse drug reactions to ethanbutol are few .
T/F

A

T

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Q

STREPTOMYCIN
It is bacter_____ for tubercle bacilli .

A

Icidal

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Q

Bacterial resistance has developed to streptomycin over the years.

T/F

A

T

Q

ADRs of streptomycin : features of ________ effect such as _____,______,______

A

vestibule-cochlear

tinictus, deafness, distortion of balance.

Q

Pyrazmanide – synthetic pyrazine analog of _________

A

nicotinamide

Q

AMINOGLYCOSIDE ANTIBIOTICS

List 7

A

Gentamicin, tobramycin, amikacin, netilmicin, kanamycin, streptomycin and neomycin.

Q

AMINOGLYCOSIDE ANTIBIOTICS

They all contain ______ in _____ linkage.

The aminoglycosides are used primarily to treat infections caused by gram-________ bacteria.

A

amino sugars in glycosidic

negative

Q

Aminoglycosides

They are _____, and their polarity is a part responsible for their pharmacokinetic properties e.g. None is ____________, _______ conc found in CSF, and all are relatively ________ by the normal kidney.

A

polycations

adequately absorbed after oral administration

inadequate

rapidly excreted

Q

AMINOGLYCOSIDE ANTIBIOTICS

They act to interfere with _______ in susceptible microorganisms.

A

protein synthesis

Q

Aminoglycosides

Mutations affecting _________, the target for these drugs can rapidly confer marked resistance to their action.

A

proteins in the bacterial ribosome

Q

Aminoglycosides

______ acquisition leading to elaboration of drug metabolizing enzymes can also result in resistance.

A

Plasmid

Q

There can’t be cross resistance to Aminoglycosides

T/F

A

F

There can

Q

Serious toxicity is a major limitation to the usefulness of aminoglycosides: ————— and__________

A

ototoxicity( auditory& vestibular)

serious nephrotoxicity.

Q

History: The dev of streptomycin was the result of a well planned scientific search for antibact substances. In 1943, a strain of _________ was isolated that elaborated a potent antimicrobial substance, streptomycin.

A

streptomyces griseus

Q

________ and _____ are both broad-spectrum derived from species of the actinomycete micromonospora.

A

Gentamicin and netilmicin

Q

Aminoglycosides MECH OF ACTION:

They are rapidly bacter_____.

They act at the ______, where they inhibit ____________ and decrease the fidelity of translation of mRNA

A

icidal; ribosome

protein synthesis

Q

Aminoglycosides MECH OF ACTION:

Aminoglycosides diffuse readily through _________ in the outer memb of gran- negative bacteria and thereby enter the __________

A

aqueous channel formed by porin proteins

periplasmic space

Q

Aminoglycosides MECH OF ACTION:

transport of aminoglycosides across cytoplasmic (inner) membrane is dependent on transport, partly because of a requirement of a ____________ to drive permeation of these antibiotics.

This is the ________ phase __, and it can be blocked or inhibited by ____ cations e.g ca2+), _________ , a ______ease in pH, and (aerobic or anaerobic ?) environment.

A

membrane potential (interior negative)

energy – dependent;1

divalent; hyperosmolality

decr; anaerobic

Q

The pH and anaerobiasis impair the ability of the bacteria to ___________________

A

maintain the driving force necessary for transport (members potential).

Q

Following transport across the cytoplasmic membrane, the aminoglycosides bind to _____ and inhibit the ___________.

This phase termed ______ phase II (EDP2), is thought to be liked with disruption of the structure of the cytoplasmic membrane.

A

polysomes

synthesis of proteins

energy dependent

Q

The 10 intra cellular site of action of the aminoglycosides is the ___ ribosomal subunit which consists of 21 proteins & a single 165 molecule of RNA, alteration of at least ___ of these proteins markedly affect the action of _______.

A

30s; 3; Streptomycin

Q

The other aminoglycosides(besides streptomycin) apart from binding to the _____ ribosomal subunit appear to bind to several sites on the _____ ribosomal subunit as well.

A

30S

50s

Q

Aminoglycosides disrupt the normal cycle of ribosomal function by interfaring at least in part with the ___________ that occurs at the ribosome (intuition).

A

1st step of protein synthesis

Q

MICROBIAL RESSITANCE TO THE AMINOGLYCOSIDES
Factors responsible are

a) failure of ________ of the antibiotic

b)______ of the drug for the bacterial ribosome

c) most importantly, ________ of the drug by microbial enzymes.

A

permeation

low affinity

inactivation

Q

The metabolites of the aminoglycosides may compete with the unaltered drug for —————- but they are incapable of ___________ and _________.

A

intra cellular transport

binding effectively to ribosomes and interfering with protein synthesis

Q

Strictly anaerobic bacteria are (susceptible or resistant?) to the aminoglycosides

With reason

A

Resistant

since their transport across the cytoplasmic (inner) membrane is oxygen – dependent

Q

ANTIBACTERIAL ACTIVITY of aminoglycosides is Mainly towards gram- ______bacilli

A

negative

Q

_______ and _______ are active in vitro against more than 95% of strains of staphylococcus aureus and most strains of staph. but they should not be used alone in their infections because the clinical efficacy has not been documented

A

Getamicin and tobramycin

Q

sensitive microorganisms are defined as those inhibited by ___________ but that are not associated with a high incidence of ______

this value is _____ ml for gent, tobra, netilmicin and ______ for amikacin and kanamycin .

A

peak conc that can be achieved clinically in plasma

toxicity

4 to 8 ; 8 to 16

Q

Amikacin and netilmicin have retained their activity against nosocromial infections because of ________________

A

resistance to the aminoglycoside metabolizing Enzymes.

Q

ABSORPTION of aminoglycosides

They are highly polar cautions hence (well or poorly?) absorbed from GIT >1% is absorbed ff oral or rectal admin

A

Poorly

Q

Aminoglycosides are inactivated in the GIT

T/F

A

F

They are not inactivated in GIT

Q

Aminoglycosides are eliminated quantitatively in feces.

T/F

A

T

Q

Absorption of Aminoglycosides is ___eased when there is bacillary dysentery but that of _____ is not altered in the presence of inflammatory disease of the bowel.

A

Decr

neomycin

Q

Repeated oral or rectal admin of Aminoglycosides may result in accumulation to toxic concentrations in patients with ____ impairment.

Instillation into body cavities with ____ surfaces may result in rapid absorption and unexpected toxicity.

A

renal

serosa

Q

Aminoglycosides

Intoxication may also occur when applied topically to large wounds, or cutaneous ulcers particular with renal insufficiency.

T/F

A

T

Q

Rapid absorption of aminoglycosides from _____ and _____ injection (Pick Plasma Conc 30 to 90 minutes similar to the peak after 30 minutes of completion of I.V. infusion of an equal dose over a 30 min period).

A

I/M and SC

Q

DISTRIBUTION of aminoglycosides :

Because of their ____ nature they are largely excluded from most cells, from ____ and the ___.

Inflamation ____eases penetration into peritoneal and pericardial cavities.

Intrathecal or intraventricular Admin is necessary in cases of gram-_______ bacillary ______ in adults as opposed to neonates who have in-mature _____.

A

polar; CNS; eye

incr

negative; meningitis

BBB

Q

ELIMATION of Aminoglycosides

Excretion almost entirely by ___________________ of 50 to 200 ml are achieved.

A large fraction of (eneterally or parenterally?) admin dose is excreted unchanged during 1st 24 hours with most of this appearing in 1st 12 hours.

A

glomerular filtration & conc in urine

parenterally

Q

The t 1⁄2 of Aminoglycosides is ____ in plasma.

A

2 – 3 hours

Q

Renal clearance of Aminoglycosides is approx 2/3 of the simultaneous creatinine clearance (this suggest some tubular ________).

A

resorption

Q

UNTOWARD EFFECTS of Aminoglycosides

Reversible & irreversible ______,________,and _______.

A

vestibular, cochlear & renal toxicity

Q

UNTOWARD EFFECTS of Aminoglycosides

Accumulation in the ___________ of the inner ear
Sustained exposure leads to permanent dysfucntiond effects.
(Younger or Older ?) patients more susceptible to ototoxicity.

A

perilymph & endolymph

Older

Q

UNTOWARD EFFECTS of Aminoglycosides

________ and _________ have more predominant vestibular effects while

_____,_______, and _______ lmpact auditory function more.

__________ both equally

other notable ADRs include
__________ – renal cortex

. Dysfunction of ______ nerve

Peripheral neuritis

A

streptomycin and gentimicin

amikacin, kanamycin and neomycin

Tobramycin

Nephotoxicity

optic

Q

_________ Aminoglycoside is used in Combination therapy in UTI especially when seirous untio sensitivity results are out.

A

Gentamicin

Q

tobramycin has Antimicrobial activity & pharmacokinetics similar to gentimicin

T/F

A

T

Q

________ Aminoglycoside has the Broadest antimicrobial activity

A

Amikacin

Q

Amikacin is also has resistance to aminoglycoside – inactivating enzymes hence special role in hospitals where gentimicin and tobramycin resistant microorganisms are prevalent.

T/F

A

T

Q

NET ILMICIN is metabolized by majority of the aminoglycoside – metabolizing enzymes

T/F

A

F

It’s not

Q

Mention 4 adverse effects of using Aminoglycosides

A

Ototoxicity

Nephrotoxicity

Paralysis

Skin rash

Q

Acyclovir- ________
Zidovudine-_________
Rifampicin-_______
Quinolones-______

A

DNA polymerase
Reverse transcriptase
Rna polymerase
Topoisomerase and dna gyrase

Q

Pristinamycins

Bactericidal or bacteriostatic

A

bacteriostatic

Q

Chloramphenicol

Bactericidal or bacteriostatic

A

bacteriostatic

Q

Broad spectrum Aminoglycosides- ______, _____, ______, and _____

A

gentamicin
netilmicin
Amikacin
Neomycin

Q

Aminoglycosides

High or Low therapeutic index?

A

Low

Q

TOBRAMYCIN
Antimicrobial activity & pharmacokinetics similar to ______ but superior In treating ______

A

gentimicin

Pseudo aerguernosa

Q

Aminoglycosides can undergoe cross resistance

Tetracyclines can undergoe cross resistance

T/F

A

T
T

Q

Aminoglycosides are well absorbed orally

T/F

Why?

A

F

Are polar cations

Q

Aminoglycosides administration = all are ____ EXCEPT ______ and ______

A

IV

KANA and NEO

Q

Aminoglycosides administration = Poor absorption and distribution but loves ____,______,_______.

A

skeletal muscle, kidney, and inner ear

Q

neomycin can also be given topically

T/F

A

T

Q

________ Aminoglycoside is also used clear the git before surgery

A

Neomycin

Q

Good for nosocomial-___,______

Similar activity- _____,_______

For UTI- _______

A

Amikacin, netilmicin

gentamicin and Tobramycin

gentamicin