What is antimicrobial

Antimicrobials also called antibiotics are used to treat or prevent some types of bacterial infection. Antimicrobials work by killing bacteria or preventing them from reproducing and spreading. But they don’t work for everything. When it comes to antimicrobialss, take your doctor’s advice.

Antimicrobials don’t work for viral infections such as colds and flu, and most coughs and sore throats.

Many mild bacterial infections also get better on their own without using antimicrobials.

Taking antimicrobials when you don’t need them puts you and your family at risk of a longer and more severe illness.

Antimicrobials are no longer routinely used to treat infections because:

• many infections are caused by viruses, so antimicrobials aren’t effective
• antimicrobials are often unlikely to speed up the healing process and can cause side effects
• the more antimicrobials are used to treat trivial conditions, the more likely they are to become ineffective for treating more serious conditions

Both the Centers for Disease Control and Prevention (CDC) and health organizations across the world are trying to reduce the use of antimicrobials, especially for conditions that aren’t serious.

For example, antimicrobials are no longer routinely used to treat chest infections, ear infections in children and sore throats.

When antimicrobials are used

Antimicrobials may be used to treat bacterial infections that:

• are unlikely to clear up without antibiotics
• could infect others unless treated
• could take too long to clear without treatment
• carry a risk of more serious complications

People at a high risk of infection may also be given antibiotics as a precaution, known as antibiotic prophylaxis.

Antimicrobial resistance

Antimicrobial resistance (antibiotic resistance) happens when germs like bacteria and fungi develop the ability to defeat the drugs designed to kill them. That means the germs are not killed and continue to grow. Infections caused by antimicrobial-resistant germs are difficult and sometimes impossible, to treat. In most cases, antimicrobial-resistant infections require extended hospital stays, additional follow-up doctor visits, and costly and toxic alternatives.

Antimicrobial resistance (antibiotic resistance) does not mean your body is becoming resistant to antibiotics; it is that bacteria have become resistant to the antibiotics designed to kill them.

Antimicrobial resistance (antibiotic resistance) has the potential to affect people at any stage of life, as well as the healthcare, veterinary, and agriculture industries, making it one of the world’s most urgent public health problems.

Antimicrobial resistance (antibiotic resistance) is one of the biggest public health challenges of our time. Each year in the U.S., at least 2 million people get an antibiotic-resistant infection, and at least 23,000 people die ¹. Fighting this threat is a public health priority that requires a collaborative global approach across sectors.

No one can completely avoid the risk of resistant infections, but some people are at greater risk than others (for example, people with chronic illnesses). If antibiotics lose their effectiveness, then scientists lose the ability to treat infections and control public health threats.

Many medical advances are dependent on the ability to fight infections using antibiotics, including joint replacements, organ transplants, cancer therapy, and treatment of chronic diseases like diabetes, asthma, and rheumatoid arthritis.

How antimicrobial resistance happens

Antimicrobials save lives but any time antimicrobials are used, they can cause side effects and lead to antimicrobial resistance.

Since the 1940s, antimicrobials have greatly reduced illness and death from infectious diseases. However, as you use the drugs, germs develop defense strategies against them. This makes the drugs less effective.

Antimicrobials treat infections caused by microbes

Microbes are very small living organisms, like bacteria. Most microbes are harmless and even helpful to humans, but some can cause infections and disease. Drugs used to treat these infections are called antimicrobials. The most commonly known antimicrobial is antibiotics, which kill or stop the growth of bacteria.

Two types of microbes

1. Bacteria cause illnesses such as strep throat and food poisoning. Bacterial infections are treated with drugs called antibiotics (such as penicillin).
2. Fungi cause illnesses like athlete’s foot and yeast infections. Fungal infections are treated with drugs called antifungals.

How germs become resistant

1. You get an infection. There are a lot of bacteria making you sick. Some of those bacteria are resistant to antibiotics.
2. Antibiotics kill the bacteria making you sick, but the resistant bacteria are not killed. Antibiotics also kill good bacteria that protect the body from infection.
3. Antibiotic resistant bacteria have defense strategies that protect them from antibiotics. They multiply and continue to make you sick.
4. Antibiotic resistant bacteria can give their drug-resistance to other bacteria. Antibiotics cannot treat your sickness, and people can spread these resistant germs to others.

Germ defense strategies

To survive, germs are constantly finding new defense strategies, called “resistance mechanisms,” to avoid the effects of antibiotics. Bacteria develop resistance mechanisms by using instructions provided by their DNA. Often, resistance genes are found within plasmids, small pieces of DNA that carry genetic instructions from one germ to another. This means that some bacteria can share their DNA and make other germs become resistant.

Germs can use defense strategies to resist the effects of antibiotics. Here are a few examples.

Table 1. Examples of defense strategies for germs

Resistance Mechanisms (Defense Strategies)	Description
Restrict access of the antibiotic	By limiting the number or changing the size of the openings in the cell wall, resistant bacteria can keep antibiotic drugs from entering the cell altogether.Example: Gram-negative bacteria have an outer layer (membrane) that protects them from their environment. These bacteria can use this membrane to selectively keep antibiotic drugs from entering.
Get rid of the antibiotic	Resistant bacteria can use pumps in their cell walls to remove antibiotic drugs that enter the cell.Example: Some Pseudomonas aeruginosa bacteria can produce pumps to get rid of several different important antibiotic drugs, including fluoroquinolones, beta-lactams, chloramphenicol, and trimethoprim.
Destroy the antibiotic	Some resistant bacteria use enzymes to break down the antibiotic drug and make it ineffective.Example: Klebsiella pneumoniae bacteria produce enzymes called carbapenemases, which break down carbapenem drugs and most other beta-lactam drugs
Change the antibiotic	Other resistant bacteria use enzymes to alter the antibiotic drug so that it loses its effectiveness.Example: Staphylococcus aureus bacteria add compounds to aminoglycoside drugs to change its function.
Bypass the effects of the antibiotic	Some antibiotic drugs are designed to disrupt important processes critical to a bacteria’s survival, like the process of making nutrients. If successful, the antibiotic drug will keep the bacterium from performing all the steps needed in the process. Some resistant bacteria, however, have developed different and new processes to get around these drug disruptions. The new process may be slower but they can still bypass the effects of the drug.Example: Some Staphylococcus aureus bacteria can bypass the drug effects of trimethoprim.
Change the targets for the antibiotic	Many antibiotic drugs are designed to single out and destroy specific parts (or targets) of a bacterium. Resistant bacteria can change the look of their targets so that the antibiotic does not recognize and destroy them, allowing the bacteria to survive.Example: E. coli bacteria with the mcr-1 gene can add a compound to the outside of the cell wall so that the drug colistin cannot latch onto it.

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Antimicrobial resistance and superbugs

The overuse of antimicrobials in recent years means they’re becoming less effective and has led to the emergence of “superbugs”. These are strains of bacteria that have developed resistance to many different types of antibiotics, including:

• Methicillin-resistant Staphylococcus aureus (MRSA)
• Clostridium difficile (C. diff)
• The bacteria that cause multi-drug-resistant tuberculosis (MDR-TB)
• Carbapenemase-producing Enterobacteriaceae (CPE)

These types of infections can be serious and challenging to treat, and are becoming an increasing cause of disability and death across the world.

The biggest worry is that new strains of bacteria may emerge that can’t be effectively treated by any existing antibiotics.

Antimicrobial treatment

Antimicrobials are used to treat or prevent some types of bacterial infections. They aren’t effective against viral infections, such as the common cold or flu.

Antibiotics should only be prescribed to treat conditions:

• that aren’t especially serious but are unlikely to clear up without the use of antibiotics – such as moderately severe acne
• that aren’t especially serious but could spread to other people if not promptly treated – such as the skin infection impetigo or the sexually transmitted infection chlamydia
• where evidence suggests that antibiotics could significantly speed up recovery – such as a kidney infection
• that carry a risk of more serious complications – such as cellulitis or pneumonia

People at risk of bacterial infections

Antibiotics may also be recommended for people who are more vulnerable to the harmful effects of infection. This may include:

• people aged over 75 years
• babies less than 72 hours old with a confirmed bacterial infection, or a higher than average risk of developing one
• people with heart failure
• people who have to take insulin to control their diabetes
• people with a weakened immune system – either because of an underlying health condition such as HIV infection or as a side effect of certain treatments, such as chemotherapy

Antibiotics to prevent infection

Antimicrobials are sometimes given as a precaution to prevent, rather than treat, an infection. This is known as antibiotic prophylaxis.

Antibiotic prophylaxis is normally recommended if you’re having surgery on a certain part of the body which carries a high risk of infection or where infection could lead to devastating effects.

For example, it may be used if you’re going to have:

• some types of eye surgery – such as cataract surgery or glaucoma surgery
• joint replacement surgery
• breast implant surgery
• pacemaker surgery
• surgery to remove the gall bladder
• surgery to remove the appendix

Your surgical team will be able to tell you if you require antibiotic prophylaxis.

Bites or wounds

Antibiotic prophylaxis may be recommended for a wound that has a high chance of becoming infected – this could be an animal or human bite, for example, or a wound that has come into contact with soil or feces.

Medical conditions

There are several medical conditions that make people particularly vulnerable to infection, making antibiotic prophylaxis necessary.

For example, the spleen plays an important role in filtering out harmful bacteria from the blood. People who have had their spleen removed, people having chemotherapy for cancer, or those with the blood disorder sickle cell anemia, where their spleen doesn’t work properly, should take antibiotics to prevent infection.

In some cases, antibiotic prophylaxis is prescribed for people who experience a recurring infection that’s causing distress or an increased risk of complications, such as:

• cellulitis
• a urinary tract infection
• genital herpes
• rheumatic fever

Antimicrobial medications

Antimicrobial agents are classically grouped into 2 main categories based on their in vitro effect on bacteria: bactericidal and bacteriostatic. Common teaching often explains that bactericidal antibiotics “kill” bacteria and bacteriostatic antibiotics “prevent growth” of bacteria ³. The true definition is not so simple. To accurately define each category, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) must be understood ³. The lowest concentration that inhibits visible bacterial growth at 24 hours is the minimum inhibitory concentration (MIC) ⁴. The minimum bactericidal concentration (MBC) is the concentration of an antibiotic that reduces bacterial density by 1000-fold at 24 hours ⁴. Bacteriostatic activity is further defined by an MBC to MIC ratio greater than 4; whereas, an MBC to MIC ratio less than or equal to 4 is bactericidal ⁴. The clinical implications of antibiotic efficacy depend heavily on many factors not limited to: pharmacokinetic and pharmacodynamic principles, the particular bacteria, bacterial load, and site of infection. This is further complicated by the ability of some bacteriostatic antibiotics to exhibit bactericidal activity against particular bacteria ⁵. Therefore, bacteriostatic antibiotics also kill bacteria, but the laboratory definition makes it seem as if they do not. For example, a bacteriostatic antibiotic such as linezolid can be bactericidal against Streptococcus pneumoniae ⁵. This concept works in reverse, and bactericidal antimicrobials may also be bacteriostatic against certain bacterial strains and conditions. Conflicting data exist as to whether the necessity for bactericidal antibiotics is needed for severely ill or immunosuppressed patients ⁵.

Types Antimicrobial Drugs

Drug Class and Specific Antibiotics

Bacteriostatic antibiotics

• Glycylcyclines: Tigecycline
• Tetracyclines: Doxycycline, minocycline – can be used to treat a wide range of infections, but are commonly used to treat moderate to severe acne and rosacea
• Lincosamides: Clindamycin
• Macrolides: Azithromycin, clarithromycin, erythromycin – can be particularly useful for treating lung and chest infections, or an alternative for people with a penicillin allergy, or to treat penicillin-resistant strains of bacteria
• Oxazolidinones: Linezolid
• Sulfonamides: Sulfamethoxazole

Bactericidal antibiotics

• Aminoglycosides: Tobramycin, gentamicin, amikacin – tend to only be used in hospital to treat very serious illnesses such as septicaemia, as they can cause serious side effects, including hearing loss and kidney damage; they’re usually given by injection, but may be given as drops for some ear or eye infections
• Cephalosporins:
  • First generation cephalosporins include cefadroxil, cefazolin, cephalexin, and cephradine, and these are active against many gram-positive cocci, including penicillinase-producing Staphylococcus aureus.
  • Second generation cephalosporins include cefaclor, cefoxitin, cefprozil, cefonicid, and cefuroxime; these have broader antibacterial activity, and additional sensitive organisms including Citrobacter, Enterobacter, Haemophilus influenzae, Neisseria and Serratia species.
  • Third generation cephalosporins include cefdinir, cefditoren, cefixime, cefoperazone, cefotaxime, cefpodoxime, ceftazidime, ceftibuten, ceftizoxime, and ceftriaxone, which are less active than first- and second generation drugs against gram-positive bacteria, but more active against gram-negative organisms and have greater stability against beta-lactamases.
  • Fourth generation cephalosporins include cefepime, which are active against a wide range of both gram-positive and gram-negative organisms.
  • Fifth generation cephalosporins include ceftaroline and ceftolozane/tazabactam, which are active against a wide range of both gram-positive and gram-negative organisms including methicillin resistant Staphylococcus aureus (MRSA). These agents are sometimes referred to as advanced generation rather than fifth generation cephalosporins.
• Beta-lactams (penicillins, cephalosporins, carbapenems): Amoxicillin, cefazolin, meropenem. Penicillins (such as penicillin and amoxicillin) – widely used to treat a variety of infections, including skin infections, chest infections and urinary tract infections
• Fluoroquinolones: Ciprofloxacin, levofloxacin, moxifloxacin – broad-spectrum antibiotics that can be used to treat a wide range of infections
• Glycopeptides: Vancomycin
• Cyclic Lipopeptides: Daptomycin
• Nitroimidazoles: Metronidazole

Antimicrobial special precautions

There are some important things to consider before taking antibiotics.

Penicillin

Don’t take one of the penicillin-based antibiotics if you’ve had an allergic reaction to them in the past. People who are allergic to one type of penicillin will be allergic to all of them.

People with a history of allergies, such as asthma, eczema or hay fever, are at higher risk of developing a serious allergic reaction (anaphylaxis) to penicillins, although cases are rare.

Penicillins may need to be used at lower doses and with extra caution if you have:

• severe kidney disease
• liver disease

Pregnancy and breastfeeding

Most penicillins can be used during pregnancy and breastfeeding in the usual doses.

Tell your healthcare professional if you’re pregnant or breastfeeding, so they can prescribe the most suitable antibiotic for you.

Cephalosporins

If you previously had an allergic reaction to penicillin, there’s a chance that you may also be allergic to cephalosporins.

Cephalosporins may not be suitable if you have kidney disease, but if you need one you will probably be given a lower than usual dose.

If you’re pregnant or breastfeeding, or have acute porphyria, check with your doctor, midwife or pharmacist before taking cephalosporins.

Aminoglycosides

Aminoglycosides are normally only used in hospital to treat life-threatening conditions such as septicaemia, as they can cause kidney damage in people with pre-existing kidney disease.

They’re only used during pregnancy if your doctor believes they’re essential.

Tetracyclines

The use of tetracyclines isn’t usually recommended unless absolutely necessary in the following groups:

• people with kidney disease – except doxycycline, which can be used
• people with liver disease
• people with the autoimmune condition lupus – which can cause skin problems, joint pain and swelling, and fatigue (feeling tired all the time)
• children under the age of 12
• pregnant or breastfeeding women

Tetracyclines can make your skin sensitive to sunlight and artificial sources of light, such as sun lamps and sunbeds.

You should avoid prolonged exposure to bright light while taking these drugs.

Macrolides

You shouldn’t take macrolides if you have porphyria – a rare inherited blood disorder.

If you’re pregnant or breastfeeding, the only type of macrolide you can take is erythromycin (Erymax, Erythrocin, Erythroped or Erythroped A) unless a different antibiotic is recommended by your doctor.

Erythromycin can be used at the usual doses throughout your pregnancy and while you’re breastfeeding.

Other macrolides shouldn’t be used during pregnancy, unless advised by a specialist.

Fluoroquinolones

Fluoroquinolones aren’t normally suitable for women who are pregnant or breastfeeding.

Antimicrobial drug interactions

Antibiotics can sometimes interact with other medicines or substances. This means it can have an effect that is different to what you expected.

Some of the more common interactions are listed below, but this isn’t a complete list.

If you want to check that your medicines are safe to take with your antibiotics, ask your doctor or local pharmacist.

Some antibiotics need to be taken with food, while others need to be taken on an empty stomach. You should always read the patient information leaflet that comes with your medicine.

Alcohol

You should completely avoid alcohol while taking the antibiotics metronidazole or tinidazole, and for 48 hours afterwards, as this combination can cause very unpleasant side effects, such as:

• feeling and being sick
• stomach pain
• hot flushes
• headaches

It’s recommended that you don’t drink alcohol while taking antibiotics. However, as long as you drink in moderation, alcohol is unlikely to interact significantly with your medication.

Combined oral contraceptives

Some antibiotics, such as rifampicin and rifabutin, can reduce the effectiveness of the combined oral contraceptive pill.

If you’re prescribed rifampicin or rifabutin, you may need to use additional contraception, such as condoms, while taking antibiotics. Speak to your doctor, nurse or pharmacist for advice.

Medications

Some of the medications you may need to avoid, or seek advice on, while taking a specific class of antibiotic are outlined below.

Penicillins

It’s usually recommended that you avoid taking penicillin at the same time as methotrexate, which is used to treat psoriasis, rheumatoid arthritis and some forms of cancer. This is because combining the two medications can cause a range of unpleasant and sometimes serious side effects.

However, some forms of penicillin, such as amoxicillin, can be used in combination with methotrexate.

You may experience a skin rash if you take penicillin and allopurinol, which is used to treat gout.

Cephalosporins

Cephalosporins may increase the chance of bleeding if you’re taking blood-thinning medications (anticoagulants) such as heparin and warfarin.

If you need treatment with cephalosporins, you may need to have your dose of anticoagulants changed or additional blood monitoring.

Aminoglycosides

The risk of damage to your kidneys and hearing is increased if you’re taking one or more of the following medications:

• antifungals – used to treat fungal infections
• cyclosporin – used to treat autoimmune conditions such as Crohn’s disease and given to people who have had an organ transplant
• diuretics – used to remove water from the body
• muscle relaxants

The risk of kidney and hearing damage has to be balanced against the benefits of using aminoglycosides to treat life-threatening conditions such as septicaemia.

In hospital, blood levels are carefully monitored to ensure the antibiotic is only present in the blood in safe amounts. If aminoglycosides are used properly in topical preparations, such as ear drops, these side effects don’t occur.

Tetracyclines

You should check with your doctor or pharmacist before taking a tetracycline if you’re currently taking any of the following:

• vitamin A supplements
• retinoids – such as acitretin, isotretinoin and tretinoin, which are used to treat severe acne
• blood-thinning medication
• diuretics
• kaolin-pectin and bismuth subsalicylate – used to treat diarrhoea
• medicines to treat diabetes – such as insulin
• atovaquone – used to treat pneumonia
• antacids – used to treat indigestion and heartburn
• sucralfate – used to treat ulcers
• lithium – used to treat bipolar disorder and severe depression
• digoxin – used to treat heart rhythm disorders
• methotrexate
• strontium ranelate – used to treat osteoporosis
• colestipol or colestyramine – used to treat high cholesterol
• ergotamine and methysergide – used to treat migraines

Macrolides

It’s highly recommended that you don’t combine a macrolide with any of the following medications unless directly instructed to by your doctor, as the combination could cause heart problems:

• terfenadine, astemizole and mizolastine – these are all antihistamines used to treat allergic conditions such as hay fever
• amisulpride – used to treat episodes of psychosis
• tolterodine – used to treat urinary incontinence
• statins – used to treat high cholesterol

Fluoroquinolones

You should check with your doctor or pharmacist before taking a fluoroquinolone if you’re currently taking any of the following:

• theophylline – used to treat asthma; also found in some cough and cold medicines
• non-steroidal anti-inflammatory drug (NSAID) painkillers – such as ibuprofen
• ciclosporin
• probenecid – used to treat gout
• clozapine – used to treat schizophrenia
• ropinirole – used to treat Parkinson’s disease
• tizanadine – used to treat muscle spasms
• glibenclamide – used to treat diabetes
• cisapride – used to treat indigestion, heartburn, vomiting or nausea
• tricyclic antidepressants – such as amitriptyline
• steroid medications (corticosteroids)

Some fluoroquinolones can intensify the effects of caffeine (a stimulant found in coffee, tea and cola), which could make you feel irritable, restless and cause problems falling asleep (insomnia).

You may need to avoid taking medication that contains high levels of minerals or iron, as this can block the beneficial effects of fluoroquinolones. This includes:

• antacids
• zinc supplements
• some types of multivitamin supplements

How to take antibiotics

Take antibiotics as directed on the packet or the patient information leaflet that comes with the medication, or as instructed by your doctor or pharmacist.

Doses of antibiotics can be provided in several ways:

• Oral antibiotics – tablets, capsules or a liquid that you drink, which can be used to treat most types of mild to moderate infections in the body
• Topical antibiotics – creams, lotions, sprays or drops, which are often used to treat skin infections
• Injections of antibiotics – these can be given as an injection or infusion through a drip directly into the blood or muscle, and are usually reserved for more serious infections

It’s essential to take antibiotics as prescribed by your healthcare professional.

Missing a dose of antibiotics

If you forget to take a dose of your antibiotics, take that dose as soon as you remember and then continue to take your course of antibiotics as normal.

But if it’s almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Don’t take a double dose to make up for a missed one.

There’s an increased risk of side effects if you take two doses closer together than recommended.

Accidentally taking an extra dose

Accidentally taking one extra dose of your antibiotic is unlikely to cause you any serious harm.

But it will increase your chances of experiencing side effects, such as pain in your stomach, diarrhea, and feeling or being sick.

If you accidentally take more than one extra dose of your antibiotic, are worried or experiencing severe side effects, speak to your doctor.

Antimicrobial complications

Antimicrobial side effects

All medications have the potential for an adverse reaction and antibiotics are no exception. One of 5 hospitalized patients has been shown to develop an adverse reaction to an antibiotic ⁶ and nearly the same proportion of drug-related Emergency Department visits are due to adverse antibiotic reactions ⁷. An immune-mediated reaction or hypersensitivity is classified as an allergy ⁸. This includes IgE-mediated anaphylaxis and angioedema. Medications reach harmful levels in the body often due to reduced metabolism and elimination, or high dosing regimens can cause toxicity due to supratherapeutic drug levels ⁹. If a reaction occurs that is not mediated by the immune system and is unrelated to the drug level, it is known as a side effect ⁹.

The anticipation of adverse events is warranted when initiating antimicrobial therapy. Certain patients are at higher risk, for example, the elderly, patients with multiple co-morbidities, and hospitalized patients ⁶. It is important to monitor patients for reactions as many develop over time. Some antibiotics necessitate monitoring of drug levels to guide therapy for efficacy and prevention of adverse effects such as vancomycin and the aminoglycosides ¹⁰. Renal toxicities may develop if these antimicrobials maintain high trough levels; therefore, monitoring renal function is necessary for addition to drug levels.

The most common side effects of antibiotics affect the digestive system. These occur in around 1 in 10 people.

Side effects of antibiotics that affect the digestive system include:

• vomiting
• nausea (feeling like you may vomit)
• diarrhea
• bloating and indigestion
• abdominal pain
• loss of appetite

These side effects are usually mild and should pass once you finish your course of treatment.

If you experience any additional side effects other than those listed above, you should contact your doctor or the doctor in charge of your care for advice.

Antibiotic allergic reactions

Around 1 in 15 people have an allergic reaction to antibiotics, especially penicillin and cephalosporins. In most cases, the allergic reaction is mild to moderate and can take the form of:

• a raised, itchy skin rash (urticaria, or hives)
• coughing
• wheezing
• tightness of the throat, which can cause breathing difficulties

These mild to moderate allergic reactions can usually be successfully treated by taking antihistamines.

In rare cases, an antibiotic can cause a severe and potentially life-threatening allergic reaction known as anaphylaxis.

Initial symptoms of anaphylaxis are often the same as above and can lead to:

• a rapid heartbeat
• increasing difficulty breathing caused by swelling and tightening of the neck
• a sudden intense feeling of apprehension and fear
• a sharp and sudden drop in your blood pressure, which can make you feel light-headed and confused
• falling unconsciousness

Anaphylaxis is a medical emergency and can be life-threatening if prompt treatment isn’t given. Dial your local emergency services number immediately and ask for an ambulance if you think you or someone around you is experiencing anaphylaxis.

Adverse Reactions Associated with Organ Systems ⁹.

Renal

• Acute tubular necrosis
• Interstitial nephritis
• Renal failure
• Crystallization in renal tubules

Cardiac:

• QT prolongation

Hematologic

• Thrombocytopenia
• Leukopenia
• Agranulocytosis
• Abnormal platelet aggregation
• INR (international normalized ratio) increase (often due to drug interactions)

Dermatologic

• Rash
• Erythema multiforme
• Stevens-Johnson syndrome
• Toxic epidermal necrolysis

Neurologic

• Ototoxicity
• Vestibular dysfunction
• Seizure
• Peripheral neuropathy

Other

• Hepatotoxicity
• Myopathy
• Electrolyte abnormalities (i.e. hypokalemia, hypoglycemia)
• Drug-induced fever
• Drug-induced diarrhea

Antibiotic Resistance

See Antimicrobial Resistance above.

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