Aminoglycosides Pharmacology Nursing Antibiotics: Mechanism of Action, Mnemonic, Anti-Infectives

Summary

This video covers aminoglycosides, a group of antibiotics primarily targeting gram-negative bacteria. They have a bactericidal effect, making them effective for infections like septicemia, UTIs, and pneumonia. Aminoglycosides inhibit protein synthesis by binding to the 30S ribosomal subunit. They're often used with other antibiotics, like penicillin, for a synergistic effect. The video discusses key drugs in this class, how they're administered, and the importance of monitoring for nephrotoxicity, ototoxicity, and neuromuscular issues, emphasizing the need for careful patient monitoring to avoid adverse effects.

Takeaways

• 💊 Aminoglycosides are antibiotics primarily targeting gram-negative bacteria, with bactericidal effects that kill the bacteria rather than just inhibiting its growth.
• 🦠 These antibiotics are effective against bacteria like E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Serratia marcescens, but have limited effectiveness against gram-positive bacteria.
• 🧬 Aminoglycosides work by inhibiting protein synthesis in bacterial cells by targeting the 30S ribosomal subunit, leading to faulty protein production and bacterial death.
• 💉 Aminoglycosides are usually administered via the IM or IV route, as they are poorly absorbed through the gut, though certain exceptions exist (e.g., neomycin for gut infections).
• 🧪 Peak and trough levels should be closely monitored due to the narrow therapeutic index, ensuring the drug is effective while avoiding toxicity.
• 🚨 Nephrotoxicity (kidney damage) and ototoxicity (hearing damage) are major risks of aminoglycosides, requiring careful monitoring of renal function and hearing.
• 🔬 In some cases, aminoglycosides are combined with other antibiotics like penicillin for a synergistic effect, improving their ability to penetrate bacterial cells.
• 👂 Ototoxicity, or damage to the ears, is usually irreversible and may present as tinnitus, hearing loss, or dizziness, particularly in patients also taking loop diuretics.
• 🫁 Neuromuscular blockade, leading to muscle weakness or respiratory failure, is another rare but serious side effect, especially in patients with neuromuscular conditions.
• 🧴 The mnemonic 'GNATS' helps remember the main aminoglycosides: Gentamicin, Neomycin, Amikacin, Tobramycin, and Streptomycin.

Q & A

What types of bacteria do aminoglycosides primarily target?

Aminoglycosides primarily target gram-negative microorganisms such as E. coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Serratia marcescens, and Enterobacter. They are less effective against gram-positive bacteria but can target some, like Staphylococcus aureus.

How do aminoglycosides kill bacteria?

Aminoglycosides work by inhibiting protein synthesis in bacteria. They bind to the 30S subunit of the bacterial ribosome, disrupting the genetic code's reading, leading to the production of faulty proteins, which ultimately causes bacterial death.

Why are aminoglycosides often used in combination with other antibiotics?

Aminoglycosides are used with other antibiotics, like Penicillin, for a synergistic effect. Penicillin helps aminoglycosides penetrate bacterial cell walls more effectively, enhancing their ability to kill bacteria.

What is the mnemonic to remember common aminoglycoside medications?

The mnemonic to remember aminoglycosides is 'GNATS': G for Gentamicin, N for Neomycin, A for Amikacin, T for Tobramycin, and S for Streptomycin.

How are aminoglycosides typically administered?

Aminoglycosides are usually administered via intramuscular (IM) or intravenous (IV) routes because they are not well-absorbed through the gut. Exceptions include Tobramycin for inhalation in cystic fibrosis patients and Neomycin for oral use in specific conditions like hepatic encephalopathy.

What conditions can aminoglycosides effectively treat?

Aminoglycosides are used to treat septicemia, severe urinary tract infections, infections of the eyes, ears, bones, abdomen, pelvis, endocarditis, and hospital-acquired pneumonia. They can also target mycobacterial infections such as tuberculosis.

Why is monitoring peak and trough levels important when administering aminoglycosides?

Monitoring peak and trough levels ensures the medication is at a therapeutic level to effectively treat the infection while avoiding toxicity. Peak levels are monitored for effectiveness, and trough levels are monitored to prevent toxic accumulation in the body.

What are the major toxic effects of aminoglycosides?

Aminoglycosides can cause nephrotoxicity (kidney damage) and ototoxicity (hearing damage). Nephrotoxicity is often reversible, but ototoxicity, affecting hearing and balance, is usually permanent.

How can aminoglycosides lead to neuromuscular blockade?

Aminoglycosides can cause neuromuscular blockade, leading to muscle weakness and respiratory failure, especially in patients with neuromuscular disorders or those who have received neuromuscular blocking medications during anesthesia.

What signs should nurses monitor to ensure aminoglycosides are effectively treating an infection?

Nurses should monitor for signs like the resolution of fever, normal blood pressure and heart rate, and normal white blood cell count (5,000-10,000 cells/mcL). These indicators suggest that the infection is being effectively treated.

Outlines

00:00

💉 Overview of Aminoglycosides and Their Bactericidal Effect

Aminoglycosides are a class of antibiotics that target gram-negative bacteria by killing them rather than merely inhibiting growth (bactericidal effect). They are highly effective against organisms like E. coli, Klebsiella, Pseudomonas, and more. Though mainly effective on gram-negative bacteria, they can also target some gram-positive bacteria and mycobacteria. Aminoglycosides are often used in combination with other antibiotics like penicillin to enhance their effect (synergistic effect). A mnemonic 'GNATS' (Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin) helps remember the common drugs in this group.

05:02

🔬 Mechanism of Action: Targeting the Ribosome

Aminoglycosides kill bacteria by inhibiting protein synthesis, a vital process for bacterial survival. They specifically bind to the 30S subunit of the ribosome, disrupting the reading of genetic code, leading to the production of faulty proteins. This interference with protein production results in the death of the bacteria. The ribosome consists of two subunits, 50S and 30S, and aminoglycosides particularly affect the 'A' site of the 30S subunit, preventing proper protein assembly.

10:02

🏥 Nursing Role: Monitoring and Toxicity Management

When administering aminoglycosides, nurses should ensure that patients are not allergic, check cultures, and monitor peak and trough levels to avoid toxicity. Peak levels should be measured 1 hour after IM administration or 30 minutes after IV infusion. Trough levels are measured just before the next dose. Nurses should assess whether the treatment is effective (e.g., reduced fever, normal blood pressure, and white blood cell count). It's crucial to monitor for nephrotoxicity (kidney damage) by checking urine output and renal function labs and for ototoxicity (ear damage), especially when patients take other ototoxic drugs like loop diuretics.

👂 Ototoxicity, Nephrotoxicity, and Neuromuscular Risks

Aminoglycosides can cause two primary toxic effects: nephrotoxicity (kidney damage) and ototoxicity (hearing loss or balance issues). Nephrotoxicity may be reversible, so nurses should monitor urine output and renal function tests like BUN and creatinine. Ototoxicity, affecting the cochlear and vestibular systems, is often irreversible, with symptoms like ringing in the ears or dizziness. Patients at higher risk include those taking ototoxic drugs. Additionally, aminoglycosides may cause neuromuscular blockade, especially in patients with preexisting neuromuscular conditions, leading to muscle weakness and respiratory failure.

Keywords

💡Aminoglycosides

Aminoglycosides are a group of antibiotics that primarily target gram-negative bacteria. They have a bactericidal effect, meaning they kill the bacteria rather than just inhibiting its growth. In the video, aminoglycosides are described as effective against serious infections like septicemia, pneumonia, and UTIs, especially when used with other antibiotics for a synergistic effect.

💡Gram-negative bacteria

Gram-negative bacteria are a type of bacteria that have a thinner cell wall but a complex outer membrane, making them more resistant to some antibiotics. In the video, aminoglycosides are highlighted as particularly effective in targeting gram-negative bacteria such as E. coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa.

💡Synergistic effect

The synergistic effect refers to the enhanced effectiveness of two or more medications when used together. In the context of the video, combining aminoglycosides with antibiotics like penicillin allows the aminoglycoside to penetrate the bacterial cell wall more effectively, increasing its ability to kill bacteria.

💡Bactericidal

Bactericidal refers to an antibiotic's ability to kill bacteria, as opposed to simply inhibiting its growth (bacteriostatic). Aminoglycosides are described as having a bactericidal effect, directly killing bacteria by inhibiting protein synthesis in bacterial cells, which is critical for their survival.

💡Ribosome

Ribosomes are cellular structures responsible for protein synthesis. In the video, aminoglycosides are explained as working by binding to the 30S subunit of bacterial ribosomes, specifically the A-site, disrupting protein production and leading to the bacteria's death. This inhibition of protein synthesis is the primary mechanism by which aminoglycosides exert their bactericidal effect.

💡Nephrotoxicity

Nephrotoxicity refers to the potential of a drug to cause damage to the kidneys. Aminoglycosides carry a risk of nephrotoxicity, especially when used at high doses or for prolonged periods. The video stresses the importance of monitoring kidney function (such as urine output and creatinine levels) to avoid kidney damage in patients receiving these antibiotics.

💡Ototoxicity

Ototoxicity is a toxic effect on the ear, particularly the hearing structures, which can lead to hearing loss or dizziness. The video highlights that aminoglycosides can cause irreversible ototoxicity, making it important for patients to monitor for symptoms such as ringing in the ears (tinnitus) or dizziness while on the medication.

💡Peak and trough levels

Peak and trough levels refer to the highest and lowest concentrations of a drug in a patient's blood. Monitoring these levels is crucial when administering aminoglycosides, as the video explains. The peak ensures the drug reaches an effective concentration to kill bacteria, while the trough helps prevent toxic side effects by ensuring levels don't get too high.

💡Protein synthesis

Protein synthesis is the process by which cells build proteins, which are vital for cellular functions and survival. In the video, aminoglycosides are said to work by disrupting bacterial protein synthesis. By binding to the bacterial ribosome, they prevent the formation of proper proteins, ultimately leading to the bacteria's death.

💡Mycobacterium tuberculosis

Mycobacterium tuberculosis is the bacterium responsible for tuberculosis (TB). The video mentions that aminoglycosides can target mycobacteria like M. tuberculosis, making these antibiotics useful in treating TB infections, especially in cases resistant to other treatments.

Highlights

Aminoglycosides are a group of antibiotics primarily targeting gram-negative bacteria.

These antibiotics are bactericidal, meaning they kill bacteria rather than just inhibiting their growth.

Aminoglycosides target bacteria like E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens, and Enterobacter.

They are used to treat severe infections like septicemia, urinary tract infections, and hospital-acquired pneumonia.

Aminoglycosides are often combined with other antibiotics like Penicillin for a synergistic effect.

The mnemonic 'GNATS' helps to remember aminoglycosides: Gentamicin, Neomycin, Amikacin, Tobramycin, and Streptomycin.

These antibiotics work by inhibiting protein synthesis within bacterial cells, specifically targeting the 30S ribosomal subunit.

They bind to the A-site of the 30S subunit, causing the bacteria to produce faulty proteins, leading to bacterial death.

Aminoglycosides are typically administered via injection (IM or IV) as they are poorly absorbed through the gut.

Special cases like cystic fibrosis can involve inhalation administration of Tobramycin or oral use of Neomycin for gut bacteria.

The peak and trough levels of aminoglycosides must be closely monitored to avoid toxicity, given their narrow therapeutic index.

Nephrotoxicity (kidney damage) and ototoxicity (hearing damage) are two major risks associated with aminoglycosides.

Nephrotoxicity can potentially be reversed, but ototoxicity is often irreversible.

Patients at higher risk of ototoxicity may be taking other medications like Loop Diuretics or have pre-existing conditions.

In rare cases, aminoglycosides can cause neuromuscular blockade, leading to muscle weakness and respiratory failure.

Transcripts

hey everyone it's Sarah with registered

nurse rn.com and in this video I'm going

to be covering Amino glycosides so let's

get started aminoglycosides are a

particular group of antibiotics that

Target mainly gram-negative

microorganisms therefore they're really

gram-negative Killers because they have

this bacterial subtle effect on the

bacteria where they go in and just kill

it rather than just inhibiting its

growth which would be known as having a

bacteriostatic effect now as I cover the

different types of antibiotics in this

series you're going to see that some

antibiotics are really good at killing

bacteria whereas other types just really

inhibit their growth so what

gram-negative bacteria do

aminoglycosides Target well they target

E coli klebsiella pneumonia a

pseudomonas ergonosa serratia marcessins

and interobacter now they're not really

helpful with targeting grandpas and

microorganisms but they can kill a few

such as staphylococcus aureus and then

enterococcus furthermore aminoglycosides

can Target mycobacteria infections such

as mycobacterium tuberculosis so because

of all these microorganisms that

aminoglycosides can Target they're

really good at treating certain cases of

septicemia where we have infection in

the blood severe cases of urinary tract

infection and then infections that

affect certain parts of the body such as

the eyes the ears the bone the abdomen

the pelvic areas and they can treat

cases of endocarditis where you have

infection in the heart specifically on

those heart valves and then severe cases

of pneumonia that are usually acquired

from the hospital setting because those

strains tend to be very severe now in

practice you may see that

aminoglycosides are used in combination

with other types of antibiotics and the

reason for this is because whenever you

throw an aminoglycoside on let's say

with Penicillin it all of a sudden has a

synergistic effect which means it allows

that aminoglycoside to work in ways

where it normally wouldn't be able to

work if it wasn't on board with this

other type of medication so let's say we

have Penicillin and aminoglycoside on

well aminoglycoside without penicillin

normally wouldn't be able to get inside

that cell wall and kill it but because

we have Penicillin on board we have the

synergistic effect and aminoglycoside is

able to get in and Target that bacteria

so how do we remember the medications

that are included with the

aminoglycosides well let's remember the

word Nats g-n-a-t-s so the GN part is

going to help you remember that

aminoglycosides mainly Target

gram-negative

microorganisms so the G is for

Gentamicin n is for neomycin

A is for Emma Cason T is for Tobramycin

and then the last one s is for

streptomycin now as you can see these

medications in in mycin whether

m-i-c-i-n or m-y-c-i-n but don't let

that tip you off that it's an

aminoglycoside because some other groups

of antibiotics such as the microlides

they end in nycin some of them do like

erythromycin so that might throw you off

and get you a little confused so just

try to remember the names with this

mnemonic and just know that

unfortunately it doesn't follow that

rule that sometimes we can use with

those names now how are aminoglycosides

administered well this particular group

of medications doesn't like to be

absorbed through the gut so we don't

like to give them orally but rather we

like to give them via the parental route

so the im or IV route now there are some

exceptions to this depending on what's

going on with the patient for instance

to cobramycin can be given via

inhalation to patients who have cystic

fibrosis and they have a lung infection

or we can give neomycin via the oral

route if we're trying to Target certain

bacteria in the gut for instance if the

patient has hepatic encephalopathy we

can give them neomycin to help bring

down that ammonia level or let's say the

patient's having bowel surgery we can

give them this to help prep that bowel

before they actually have surgery so now

let's talk about how aminoglycosides

work and how they actually kill that

bacteria well depending on the

antibiotic group you're talking about

they will Target certain parts of that

bacterial cell some will inhibit the

cell wall synthesis of that bacteria

While others will inhibit nucleic acid

synthesis and then some will inhibit

protein synthesis within that bacterial

cell and that is what aminoglycosides do

they inhibit protein synthesis inside

that bacterial cell so we don't get the

creation of proteins now now proteins

are really important for that bacterial

survival it's really the backbone of its

ability to thrive and survive so if we

can stop that process of that bacteria

that's inhabited our body we can kill it

and get rid of it and that's what

aminoglycosides do so what makes the

proteins in that bacteria cell it is the

ribosome so remember ribosome it's it's

what we're targeting so the ribosome is

a really cool structure it is made up of

two subunits you have a large subunit

known as 50s and then you have a smaller

one known as 30s and these two subunits

work together to their whole goal is to

stack amino acids together and make a

beautiful polypeptide chain hence our

protein

so aminoglycosides say I need to stop

this process so I'm going to affect one

of these subunits so we can't have this

happen making these polypeptide chains

so what it does is aminoglycosides binds

to the 30s on the ribosome so it binds

to the subunit particularly it's a site

so remember aminoglycoside starts with a

it targets the a site of 30s and

whenever it does this it causes its

genetic code to not be read properly so

we don't have good instructions

happening here so we're not going to

really make great healthy proteins

instead we're going to make junky

proteins and junkie proteins lead to the

death of that bacteria can't function if

it doesn't have healthy ones so there we

get that bacterial subtle effect and

that is how in the end they kill the

bacteria now let's talk about our role

as the nurse whenever we're

administering aminoglycosides so before

administer during these medications you

want to confirm that your patient is not

allergic to them and that you've

obtained any necessary cultures that

have been ordered by The Physician and

that you are monitoring the peak and

trough levels why your patient is taking

this group of antibiotics and the reason

for this is because these medications

are very powerful so we want to make

sure our patient's not becoming too

toxic on them because it has a very

narrow therapeutic index but we want to

make sure that the medications being

effective and that they have enough of

the medication in their system to really

Target that bacteria and kill it so

first let's talk about Peak so the peak

is the highest concentration of the

medication in the blood so remember this

medication can be given I am or IV so if

your patient's getting an IM you would

want to do a blood draw for the peak one

hour after the injection but let's say

your patient is getting it IV it's

typically a 30 minute infusion so you

would want to do a blood draw about 30

minutes after the infusion has been

completed and then the trough is the

lowest concentration of the medication

in the patient's system and we're really

interested in this level because it

helps us monitor for toxicity so if your

patient's getting an IM or IV you would

just collect it you do a blood draw

right before the next dose and then

another thing you want to be monitoring

for is that this medication is working

like it should so is the medication

treating this infection what are some

signs that tells you it's doing that

well the patient doesn't have a fever

anymore those fevers are dropping or

they just don't have one anymore they're

normal

they don't show signs and symptoms of

sepsis so their blood pressure is within

normal range it's not hypotensive and

their heart rates within normal range is

not tachycardic and their white blood

count is in normal range like five

thousand to ten thousand anything

greater than that tells us oh the white

blood cells are on board we've got a

massive infection because that's what

white blood cells do they target

bacteria so if they're elevated that's

not a good thing now let's talk about

the toxic effects that aminoglycosides

can have in your patient that you want

to monitor for so two terms I want you

to remember nephrotoxic and ototoxic so

in an O So in aminoglycosides remember

the n and the O for nephrotoxic and

ototoxic so nephro toxic in medical

terminology remember nephro meant

kidneys so we're talking about the

kidneys the kidneys can really be

affected and if they're affected it

could be reversed so we can reverse the

nephrotoxicity and what happens what

increases the patient's risk of having

this is that they've been using

aminoglycosides for too long or they're

on a really high dose so as a nurse when

you want to be looking out for is you

want to be looking at the patient's

urinary output make sure that they're

putting out a normal amount of urine so

typically that's 30 ml per hour for an

adult and you want to be looking at

those labs that tells you about the

renal function these will be ordered so

you want to look those over like for

instance the bun you want to make sure

that's within normal limits like 5 to

20. and they're creating level anywhere

between 0.6 to 1.2 milligrams per

deciliter it varies depending on male

and female and then you want to look at

their GFR that is a glomerular

filtration rate and this is the rate

that our glomerulus filters waste ions

and water so anything less than 90 ml

per minute is concerning so we want to

make sure that it doesn't get there now

the next type of toxic your patient can

experience is ototoxicity and Odo

remember means ears and we're

specifically talking about those hearing

structures in the ear now if your

patient experiences this unfortunately

it's not likely going to be reversed

like over here with the kidneys and what

increases your patient's risk of

developing this is if they're taking

other medications that can really cause

this to happen for instance if they're

taking Loop Diuretics like furosemide it

increases the risk of them developing

hearing problems so because this

medication can damage the vestibular and

cochlear parts of the ears you want to

tell your patient to Monitor and to

report any type of ringing in the ear

hearing loss or feeling dizzy because

this could be a sign that this

medication is messing with the ears and

then lastly this medication can cause a

neuromuscular blockade so this can be

experienced through muscle weakness and

respiratory failure and it tends to

happen in patients who've received

neuromuscular blocking medications like

during anesthesia or who have

neuromuscular disorders like myasthenia

gravis so in these patients you want to

make sure that you're on high alert for

these potential problems like muscle

weakness and respiratory failure that

could develop while taking this

medication okay so that wraps up this

review over aminoglycosides and if you'd

like to watch more review lectures over

antibiotics in this series you can

access the link in the YouTube

description below