Antibiotics

Introduction to Antibiotics

In this section, the speaker introduces the topic of antibiotics and encourages viewers to download illustrations from their website to follow along with the video.

How Antibiotics Work Against Bacteria

• Antibiotics work against bacteria by inhibiting cell wall synthesis or reducing cross-linking via penicillin binding proteins.

• The cell wall is made up of peptidoglycans and is cross-linked by tetrapeptides.

• Vancomycin and phosphomycin reduce peptidoglycan synthesis.

• Natural penicillins (penicillin G, penicillin V), anti-staphylococcal penicillins (oxacillin, nafcillin, dicloxacillin), and amino penicillins (amoxicillin, ampicillin) reduce cross-linking via penicillin binding proteins.

Other Mechanisms of Action

• Beta-lactamases break down the beta-lactam ring of penicillins.

• Tetracyclines inhibit protein synthesis by binding to 30S ribosomal subunits.

• Macrolides inhibit protein synthesis by binding to 50S ribosomal subunits.

• Aminoglycosides inhibit protein synthesis by binding to 30S ribosomal subunits and causing misreading of mRNA.

Conclusion

• Understanding how antibiotics work against bacteria can help in choosing appropriate treatment options for bacterial infections.

Beta-Lactams Antibiotics

In this section, the speaker discusses the different types of beta-lactam antibiotics and their uses.

Penicillins

• Natural penicillins, anti-staphylococcal penicillins, and aminopenicillins are all part of the beta-lactam group.

• Anti-pseudomonal penicillins are commonly used in hospitals. Piperacillin-tazobactam is a commonly used drug in this category.

• Beta-lactams reduce the cross-linking of peptidoglycans.

Cephalosporins

• There are five generations of cephalosporins with varying degrees of gram-positive and gram-negative coverage.

• First-generation cephalosporins include cefazolin and cephalexin.

• Third-generation cephalosporins like ceftriaxone and ceftazidime are heavily utilized workhorses.

Carbapenems

• Carbapenems are broad-spectrum antibiotics that can kill almost any bacteria. They include doripenem, imipenem-cilastatin, meropenem, and ertapenem.

Monobactams

• Aztreonam is a monobactam antibiotic that is primarily used for patients allergic to penicillin. It has broad-spectrum gram-negative coverage.

Vancomycin and Phosphomycin

In this section, the speaker discusses vancomycin and phosphomycin antibiotics.

• Vancomycin is a glycopeptide antibiotic that inhibits cell wall synthesis in gram-positive bacteria.

• Phosphomycin inhibits bacterial cell wall synthesis by blocking an early step in peptidoglycan synthesis.

Conclusion

In this section, the speaker concludes the discussion on antibiotics.

• Beta-lactams, carbapenems, monobactams, vancomycin, and phosphomycin are all important classes of antibiotics.

• Antibiotic resistance is a growing concern and proper use of antibiotics is crucial to prevent it.

Antibiotics Mechanism of Action

In this section, the speaker discusses the mechanism of action of antibiotics.

Beta-Lactam Antibiotics

• Penicillin-binding protein synthesizes peptidoglycan layer and cross-links them via tetrapeptide connections.

• Antibiotics bind to penicillin-binding protein and inhibit it from synthesizing cell wall or cross-linking them.

• Bacteria produce beta-lactamase enzyme that breaks beta-lactam ring in antibiotics, rendering them ineffective.

• Beta-lactamase inhibitors such as clavulanate, sulbactim, tazobactum, and avibactum are added to antibiotics to inhibit beta-lactamase.

Cell Membrane Altering Antibiotics

• Daptomycin creates efflux pumps in the cell membrane that increase permeability and produce bacterial lysis.

• Polymixins are intense drugs that alter membrane integrity and increase permeability.

Cell Wall and DNA Integrity Inhibitors

This section discusses the different types of drugs that inhibit cell wall and DNA integrity in bacteria.

Cell Membrane Integrity Inhibitors

• Polymixins are cationic detergents that bind to the cell membrane and increase its permeability.

• Daptomycin creates efflux pumps for potassium, which alters the permeability of the cell membrane.

Folic Acid Pathway Inhibitors

• Sulfonamides, such as sulfamethoxazole, inhibit the conversion of para-aminobenzoic acid into dihydrofolate.

• Trimethoprim inhibits the conversion of dihydrofolate to tetrahydrofolate, reducing nucleotide synthesis.

• These drugs reduce bacterial growth but do not kill them (bacteriostatic agents).

DNA Integrity Inhibitors

• Metronidazole increases reactive oxygen species formation, leading to breaks in DNA strands and bacterial death.

• Nitrofurantoin also increases reactive oxygen species formation, damaging DNA and RNA while inhibiting protein synthesis pathways.

Anti-Mycobacterial Drugs

In this section, the speaker discusses drugs that work against tuberculosis and how they inhibit certain enzymes.

Rifampin

• Inhibits RNA polymerase enzyme

• Commonly utilized drug for patients with tuberculosis

Fluoroquinolones

• Inhibit DNA gyrase or topoisomerase type 4 enzyme

• Activates cutting part of the enzyme, which chops up DNA into pieces

• Bactericidal agent that kills bacteria

• First generation: Ciprofloxacin (primary commonly utilized)

• Second generation (respiratory fluoroquinolones): Levofloxacin, Gemifloxacin, Moxifloxacin

Protein Synthesis Inhibitors - 50S Ribosomal Subunit

• Macrolides inhibit protein synthesis by inhibiting the 50S ribosomal subunit

• Azithromycin is a commonly utilized macrolide

• Other examples include Erythromycin and Chlorithromycin

• Clindamycin, Chloramphenicol, and Linezolid also inhibit the 50S ribosomal subunit

• These are bacteriostatic agents that reduce growth but do not kill bacteria

Protein Synthesis Inhibitors - 30S Ribosomal Subunit

• Tetracyclines inhibit protein synthesis by inhibiting the 30S ribosomal subunit

Antibiotics Mechanism of Action and Bacterial Coverage

In this section, the speaker discusses the mechanism of action and bacterial coverage of different antibiotics.

Antibiotic Mechanism of Action

• Tobramycin, Amy Casein, and Gentomycin are good aminoglycosides that kill bacteria.

• Tetracyclines like Doxycycline and Tetracycline reduce growth while Aminoglycosides kill bacteria.

Bacterial Coverage

• Gram-positive bacteria: Methicillin-sensitive Staphylococcus aureus (MSSA)

• Anti-staphylococcal penicillins like Nafcillin, Oxacillin, and Dicloxacillin are effective against MSSA.

• First-generation cephalosporins like Cephalexin or Cefazolin are also effective against MSSA.

• Fluoroquinolones are decent but not as effective as other options.

• Gram-negative bacteria: Escherichia coli (E. coli)

• Third-generation cephalosporins like Ceftriaxone or Ceftazidime are effective against E. coli.

• Fluoroquinolones like Levofloxacin or Ciprofloxacin are also effective against E. coli.

• Anaerobic bacteria: Bacteroides fragilis

• Metronidazole is the drug of choice for anaerobic infections caused by Bacteroides fragilis.

• Atypical bacteria: Mycoplasma pneumoniae

• Macrolides like Azithromycin or Clarithromycin are effective against Mycoplasma pneumoniae.

• Empiric Antibiotic Therapy

• Start patients on empiric antibiotic therapy based on the most likely pathogen.

• Tailoring Antibiotic Therapy

• After getting cultures, use antibiotics that cover the specific pathogen identified in the culture.

Antibiotics for MRSA

In this section, the speaker discusses antibiotics that are effective against Methicillin-resistant Staphylococcus aureus (MRSA), which is a type of bacteria that is resistant to many antibiotics.

Antibiotics Effective Against MRSA

• Fluoroquinolones, penicillins, and first-generation cephalosporins are not effective against MRSA.

• Ceftaryline, vancomycin, trimethoprim-sulfamethoxazole, clindamycin, and linezolid are effective against MRSA.

• Daptomycin can cover MRSA on the skin or in right-sided endocarditis but not in lung infections due to surfactant inactivation.

• The best options for treating MRSA are nafcillin, oxacillin, dicloxacillin (first-generation cephalosporin), cephalexin (second-generation cephalosporin), and fluoroquinolones.

Antibiotics for Streptococcus pneumoniae

In this section, the speaker discusses antibiotics that are effective against Streptococcus pneumoniae bacteria.

Antibiotics Effective Against Streptococcus pneumoniae

• Penicillin G and amoxicillin with beta-lactamase inhibitors are effective against Streptococcus pneumoniae.

• Third-generation cephalosporins such as ceftriaxone can also be used to treat Streptococcus pneumoniae infections.

• Fluoroquinolones such as moxifloxacin and levofloxacin can also be used to treat Streptococcus pneumoniae infections.

• Macrolides such as erythromycin and clarithromycin can be used but there is increasing resistance.

• Clindamycin is effective against Streptococcus pneumoniae, while tetracyclines, aminoglycosides, and chloramphenicol are not.

Antibiotics for Streptococcus A and B

In this section, the speaker discusses antibiotics that are effective against Streptococcus A and B bacteria.

Antibiotics Effective Against Streptococcus A and B

• Penicillin G and amoxicillin with beta-lactamase inhibitors are effective against Streptococcus A and B.

• Amino penicillins such as amoxicillin and ampicillin can also be used to treat these infections.

• Third-generation cephalosporins such as ceftriaxone can also be used to treat these infections.

• Fluoroquinolones such as moxifloxacin and levofloxacin can also be used to treat these infections.

Gram-Positive Coverage

This section covers the different antibiotics that can be used to treat gram-positive bacteria, including streptococcus and enterococcus species.

Antibiotics for Streptococcus and Enterococcus Species

• First-generation cephalosporins, such as cephalexin, are effective against these bacteria.

• Bactrim (trimethoprim-sulfamethoxazole) is also a good option.

• Clindamycin is another antibiotic that can be considered.

• Amino penicillins, such as penicillin and amoxicillin, are the best options for enterococcus species.

• Nitrofurantoin is effective against enterococcus in urinary tract infections.

• Listeria monocytogenes can be treated with amino penicillins or ampicillin/amoxicillin plus clavulanate.

Vancomycin

• Vancomycin is the best option for patients who are allergic to penicillin or have resistance to other gram-positive antibiotics.

• It does not cover vancomycin-resistant staphylococcus aureus (VRSA) or vancomycin-resistant enterococcus (VRE).

Gram-Negative Coverage

This section covers antibiotics that can be used to treat gram-negative bacteria.

HENS PECK

• Homophilus influenzae

• Enterobacter

• Neisseria gonorrhoeae and meningitidis

• Serratia

• Proteus mirabilis

• E. coli

Antibiotics for HENS PECK

• Cephalosporins are effective against most of these bacteria.

• Fluoroquinolones should not be used for strep a and b infections but may be beneficial for other HENS PECK bacteria.

• Aminoglycosides, such as gentamicin, are effective against many of these bacteria but can have toxic side effects.

• Carbapenems and monobactams are broad-spectrum antibiotics that should be reserved for severe infections or when other antibiotics have failed.

Antibiotics Coverage for Gram-Negative Bacteria

In this section, the speaker discusses the coverage of different antibiotics for gram-negative bacteria.

Penicillins

• Amino penicillins can cover most gram-negative bacteria except enterobacter, serratia, and nesseria.

• Anti-pseudomonal penicillins have broad coverage and are effective against most gram-negative bacteria.

Cephalosporins

• First-generation cephalosporins only cover peck portion of gram-negative bacteria. Second to fourth generation cephalosporins cover all types of gram-negative bacteria.

Carbapenems

• Carbapenems have broad coverage and can be used to treat most types of gram-negative bacteria. Third-generation carbapenems are the best option as they specifically cover meningitis caused by these bacteria.

Fluoroquinolones and Aminoglycosides

• Fluoroquinolones and aminoglycosides can also be used to treat gram-negative bacterial infections but do not cover nesseria well.

Pseudomonas aeruginosa and Acinetobacter baumannii

• Aminopenicillins only cover Acinetobacter baumannii but not Pseudomonas aeruginosa.

• Anti-pseudomonal penicillins like piperacillin-tazobactam are effective against both Pseudomonas aeruginosa and Acinetobacter baumannii.

Overall, carbapenems are the best option for treating most types of gram-negative bacterial infections, while anti-pseudomonal penicillins are effective against Pseudomonas aeruginosa and Acinetobacter baumannii. Fluoroquinolones and aminoglycosides can also be used but do not cover nesseria well.

Antibiotics that Cover Pseudomonas and ESBL Bacteria

In this section, the speaker discusses antibiotics that cover Pseudomonas and ESBL bacteria.

Antibiotics for Pseudomonas

• Carbapenems cover Pseudomonas and Acetobacter.

• Fluoroquinolones like Ciprofloxacin and Levofloxacin can be used for double coverage of Pseudomonas, but evidence is limited.

• Aminoglycosides will cover Pseudomonas but not Acinetobacter.

Last Resort Antibiotics

• Polymyxins are a last resort option to cover both Pseudomonas and Acinetobacter.

Antibiotics for ESBL Bacteria

• Extended Spectrum Beta-Lactamase (ESBL) bacteria require specific antibiotics.

• Carbapenems, aminoglycosides, and polymyxins are effective against ESBL bacteria.

• Ceftazidime with avibactam may also have enough coverage to break down some ESBL bacteria.

• Enterobacteriaceae such as E. coli and Klebsiella are examples of bacteria that have developed resistance via extended spectrum beta-lactamases.

Stenotrophomonas

• Stenotrophomonas requires specific antibiotics. No timestamps provided in the transcript.

Antibiotics for Gram-Negative Coverage

In this section, the speaker discusses antibiotics that are effective against gram-negative bacteria.

Polymixins and Bactrim

• Polymixins and bactrim are effective against gram-negative bacteria.

• Polymixins are particularly effective against nasty pathogens.

• Bactrim (trimethoprim sulfamethoxazole) is effective against stenotrophomonas.

Anaerobic Coverage

• Claustridium, bacterioides, peptostreptococcus, fusibacterium, and actinomycetes are anaerobic bacteria.

• Clindamycin is the primary antibiotic that covers anaerobes above the diaphragm.

• Metronidazole is good for anaerobic infections below the diaphragm and skin infections.

Atypical Coverage

• Atypical bacteria do not fit well within other categories of bacteria.

• The speaker encourages viewers to remember these random atypical bacteria.

Antibiotic Coverage for Atypical Bacteria

In this section, the speaker discusses the different antibiotics that are effective in treating atypical bacteria.

Fluoroquinolones and Macrolides

• Fluoroquinolones are preferred for Legionella.

• Macrolides cover atypical bacteria well.

Chloramphenicol and Other Antibiotics

• Chloramphenicol covers most atypical bacteria except Legionella.

• Clindamycin, aminoglycosides, and lincomycin do not cover atypical bacteria.

• Doxycycline is preferred for all types of tick-borne illnesses.

Tick-Borne Illnesses

• Borrelia burgdorferi, Rickettsia rickettsii, Ehrlichia, Anaplasma are covered by doxycycline.

• Babesiosis is not treated with doxycycline.

Treating Syphilis

In this section, the speaker discusses the preferred antibiotics for treating syphilis caused by Treponema pallidum.

Penicillin G and Doxycycline

• Penicillin G is the preferred antibiotic for treating syphilis caused by Treponema pallidum.

• If penicillin G is not an option or if there is an allergy to it, doxycycline can be considered as an alternative.

Empiric Antibiotic Therapies for Common Infections

In this section, the speaker discusses empiric antibiotic therapies for common infections when the specific type of bacteria causing the infection is unknown.

Community-Acquired Pneumonia (CAP)

• Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis are common causes of CAP.

• Atypical bacteria should also be considered.

• Empiric therapy for CAP includes macrolides or doxycycline.

Hospital-Acquired Pneumonia (HAP)

• HAP is usually caused by gram-negative bacteria and Staphylococcus aureus.

• Empiric therapy for HAP includes broad-spectrum antibiotics such as piperacillin-tazobactam or cefepime.

Urinary Tract Infections (UTIs)

• UTIs are usually caused by Escherichia coli.

• Empiric therapy for UTIs includes trimethoprim-sulfamethoxazole or nitrofurantoin.

Skin and Soft Tissue Infections

• Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of skin and soft tissue infections.

• Empiric therapy for MRSA infections includes vancomycin or linezolid.

Antibiotic Selection for Pneumonia

In this section, the speaker discusses the selection of antibiotics for pneumonia treatment.

Monotherapy for Community-Acquired Pneumonia (CAP)

• Fluoroquinolones are ideal for Legionella coverage.

• Beta-lactam plus doxycycline or macrolide is preferred for better coverage of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

Hospital-Acquired Pneumonia (HAP)

• For multi-drug resistant pathogens like MRSA and Pseudomonas aeruginosa, vancomycin is preferred for MRSA coverage and anti-pseudomonal penicillins or cefepime are commonly utilized for Pseudomonas coverage.

• Once cultures come back, unnecessary antibiotics can be peeled back to target specific bacteria.

Antibiotic Selection for Gastrointestinal Tract Infections

In this section, the speaker discusses the selection of antibiotics for gastrointestinal tract infections.

Gram-Negative Rod Coverage

• Enterobacteriaceae such as E. coli and Klebsiella pneumoniae should be covered.

• Carbapenems or anti-pseudomonal penicillins are effective in covering both gram-negative rods and anaerobes.

Anaerobic Coverage

• Clostridium species, Bacteroides, Fusobacterium, Peptostreptococcus, and Actinomyces should be covered.

Monotherapy

• Carbapenems or anti-pseudomonal penicillins are effective in covering both gram-negative rods and anaerobes.

Antibiotic Coverage for Anaerobic Infections

This section discusses the antibiotics used to treat anaerobic infections below the diaphragm and gram-negative bacteria.

Antibiotics for Anaerobic Infections

• Metronidazole plus a fluoroquinolone like cipro provides coverage for anaerobic infections and gram-negative bacteria.

• Metronidazole plus ceftriaxone gives good gram-negative coverage against collab e coli and enterobacter.

Skin and Soft Tissue Infections

This section discusses the pathogens that cause skin and soft tissue infections, including MRSA.

Pathogens for Skin and Soft Tissue Infections

• Staphylococcus aureus and Streptococcus pyogenes are common pathogens.

• For MSSA and strep A, diclox or cephalexin can be used in PO form, while nafcillin, oxacillin, or cefazolin can be used in IV form.

• For MRSA, bactrim, doxycycline or clindamycin can be used in PO form while vancomycin is preferred in IV form.

Urinary Tract Infection (UTI)

This section discusses the pathogens that cause UTIs.

Pathogens for UTIs

• Proteus mirabilis, E.coli, Klebsiella pneumoniae are common pathogens causing UTIs.

• Ceftriaxone and ciprofloxacin are effective antibiotics for pyelonephritis.

Antibiotics for Different Infections

In this section, the speaker discusses different antibiotics that can be used to treat various infections.

Antibiotics for Acute Cystitis

• Trimethoprim sulfamethoxazole is a good option if the patient is not pregnant.

• Nitrofurantoin (Macrobid) is good for post-coital prophylaxis against certain types of UTIs.

• Phosphomycin and ciprofloxacin are second-line agents.

Antibiotics for Complicated UTIs

• If the patient has a complicated UTI with nasty pathogens like pseudomonas, MRSA, or enterococcus, broad-spectrum antibiotics are needed.

• Anti-pseudomonal drugs like piperacillin-tazobactam, cefepime, ceftazidime, and aminoglycosides can be considered.

• Vancomycin can be used if there is concern about MRSA or enterococcus in patients with chronic foley catheters.

Antibiotics for Bone and Joint Infections

• For septic arthritis or osteomyelitis caused by MRSA, vancomycin is the best IV antibiotic to use.

• Ceftriaxone should be considered for neserria gonorrhea infections that spread to the joint.

Antibiotics for CNS Infections

• For community-acquired meningitis caused by strep pneumo, homophilus influenzae, or nesaria meningitidis, consider antibiotics that cover these pathogens such as ceftriaxone, vancomycin, and ampicillin.

Antibiotics for Bloodstream Infections

• For central line-associated bloodstream infections (CLABSI) or sepsis caused by pseudomonas, consider anti-pseudomonal drugs like cefepime, ceftazidime, and piperacillin-tazobactam.

Community-Acquired and Hospital-Acquired Infections

This section discusses the different types of infections that can be acquired in the community or hospital setting, and the appropriate antibiotics to use for each.

Community-Acquired Meningitis

• Antibiotics to use:

• Ceftriaxone

• Vancomycin (if concerned about MRSA)

• Ampicillin (if concerned about Listeria)

Hospital-Acquired Meningitis

• Antibiotics to use:

• Vancomycin (if concerned about MRSA)

• Cefepime (for Pseudomonas infection)

Bloodstream Infections

• Pathogens to consider:

• MRSA

• Antibiotics to use:

• Vancomycin (for MRSA)

• Piperacillin-tazobactam (for gram-negative coverage)

Sepsis of Unknown Etiology

• Antibiotics to use:

• Broad-spectrum antibiotics until the pathogen is identified

Antibiotics: Bacterial Coverage and Adverse Effects

In this section, the speaker discusses the bacterial coverage of various antibiotics and their adverse effects.

Antibiotic Coverage

• Agents that cover gram-positive bacteria include vancomycin, daptomycin, linezolid, and carbapenems.

• Agents that cover almost every gram-negative bacteria and anaerobes include piperacillin-tazobactam, carbapenems, and polymyxins.

Adverse Effects

Neurotoxicity

• Antibiotics that can cause neurotoxic effects include penicillins, cephalosporins, carbapenems, polymyxins, and linezolid.

Pancytopenia

• Antibiotics that can cause pancytopenia include penicillins (especially high doses), cephalosporins (less common), bactrim (trimethoprim-sulfamethoxazole), chloramphenicol, and linezolid.

Respiratory Failure

• Polymyxins are known to cause respiratory failure.

Other Adverse Effects

• Vancomycin can cause nephrotoxicity and ototoxicity.

• Aminoglycosides can also cause nephrotoxicity and ototoxicity. They may also induce neuromuscular blockade.

Nephrotoxic, Ototoxic and Myasthenia Gravis Medications

In this section, the speaker discusses medications that can cause kidney injury (nephrotoxic), hearing loss (ototoxic), or worsen myasthenia gravis.

Nephrotoxic Medications

• Some medications cause acute interstitial nephritis by a hypersensitivity reaction.

• Antibodies produced by the immune system cells lead to inflammation around the kidney tubules and cause acute interstitial nephritis.

• Penicillins, cephalosporins, and bactrim are examples of medications that can cause acute interstitial nephritis.

Ototoxic Medications

• Aminoglycosides and vancomycin can cause ototoxic effects.

• When combined with aminoglycosides, vancomycin can also cause ototoxic effects.

Myasthenia Gravis Medications

• Fluoroquinolones, aminoglycosides, macrolides, and clindamycin are medications that can worsen myasthenia gravis.

• Patients produce antibodies against nicotinic receptors present on skeletal muscle cells.

• Worsening myasthenia gravis can put patients into a crisis.

Teratogenic Medications

In this section, the speaker discusses medications that should be avoided during pregnancy due to their risk of causing destructive effects to the baby during gestation.

Safe Teratogenic Medications

• All penicillins and beta-lactams are safe for use during pregnancy.

• Vancomycin is also safe for use during pregnancy.

Potentially Unsafe Teratogenic Medications

• Bactrim should be avoided as it has been shown to produce kernicterus, which can cause neurotoxic effects.

• Fluoroquinolones are contraindicated in patients less than 18 years of age as they can produce cartilaginous damage and arthropathies.

• Chloramphenicol should be avoided as it can produce gray baby syndrome.

Antibiotics to Avoid During Pregnancy

In this section, the speaker discusses antibiotics that should be avoided during pregnancy due to their potential negative effects on the fetus.

Teratogenic Effects of Antibiotics

• Chloramphenicol should be avoided during pregnancy as it can cause cardiovascular collapse and respiratory failure in babies.

• Aminoglycosides are relatively safe for pregnant women.

• Tetracyclines like doxycycline should also be avoided due to their teratogenic effects.

Disulfiram Reaction

• Metronidazole is known to cause a disulfiram reaction when combined with alcohol, leading to nausea, vomiting, flushing, hypotension, and tachycardia. It is important to avoid this drug during pregnancy.

QT Prolongation

• Fluoroquinolones and macrolides are known to increase the risk of QT prolongation and torsades de pointes, a type of polymorphic ventricular tachycardia that can quickly lead to ventricular fibrillation. These drugs should be used with caution during pregnancy.

CYP 450 Inhibitors

• Fluoroquinolones, macrolides, and trimethoprim-sulfamethoxazole are known CYP 450 inhibitors that can increase drug concentrations in the bloodstream and produce negative effects when taken with other medications like warfarin.

Hemolytic Anemia

• Penicillins and cephalosporins can cause hypersensitivity reactions leading to hemolytic anemia in some patients. A Coombs test can confirm if a patient has anemia caused by these drugs.

Adverse Effects of Antibiotics

In this section, the speaker discusses the adverse effects of antibiotics and how they can worsen certain medical conditions.

Common Adverse Effects

• Trimethoprim sulfamethoxazole, fluoroquinolones, and nitrofurantoin can worsen G6PDH deficiency and cause hemolytic crisis.

• Doxycycline, trimethoprim sulfamethoxazole can cause phototoxicity when exposed to sunlight.

Penicillins

• Penicillins can cause hypersensitivity reactions that lead to anaphylactic shock due to the production of IgE antibodies.

• Penicillins can also cause pancytopenia, nephrotoxicity, and hemolytic anemia.

Cephalosporins

• Cephalosporins have been shown to potentially produce a vitamin K deficiency leading to a higher risk of bleeding.

• Ceftriaxone in particular has been shown to increase the risk of biliary sludge and cholecystitis.

• Combining cephalosporins with aminoglycosides increases the risk of acute kidney injury.

Vancomycin

• Vancomycin causes nephrotoxic and ototoxic effects. It can also cause phlebitis if pushed too fast into veins.

• Pushing vancomycin too quickly can lead to red man syndrome which causes redness, rash, muscle spasms, and hypotension.

Antibiotic Side Effects

In this section, the speaker discusses the side effects of various antibiotics and how to manage them.

Penicillin/Cephalosporins/Vancomycin/Daptomycin

• Patients may experience a febrile rash, increased eosinophils, and lymphadenopathy with eosinophilic systemic reactions.

• Daptomycin can cause rhabdomyolysis, which is the destruction of muscle cells. Consider checking CK enzyme levels in patients.

• Vancomycin can cause red man syndrome.

• Doxycycline should be taken with plenty of water and patients should remain upright after taking it to avoid pill-induced esophagitis. It can also bind to calcium in teeth causing discoloration.

• Macrolides have adverse effects such as motility dysfunction, arrhythmias, cholestasis, rash, and eosinophilia.

Clindamycin/Linezolid

• Clindamycin increases the risk of C.diff infection. Other antibiotics that increase this risk include carbapenem, trimethoprim-sulfamethoxazole, third/fourth generation cephalosporins and fluoroquinolones.

• Linezolid causes neurotoxicity like serotonin peripheral neuropathy pancytopenia and lactic acidosis.

Overall, it is important to monitor for these side effects when prescribing antibiotics and take appropriate measures to manage them.

Adverse Effects of Antibiotics

This section discusses the adverse effects of antibiotics and contraindications for their use.

Fluoroquinolones

• Can affect glucose levels causing hypoglycemia or hyperglycemia.

• Can cause destruction of cartilage, especially in children less than 18 years old.

• Increases the risk of tendon rupture, especially in patients greater than 60 years old or on steroids like prednisone.

Bactrim

• Can cause hyperkalemia.

Mechanisms of Antibiotic Resistance

This section explains how bacteria develop resistance to antibiotics.

Four Mechanisms

• Antibiotics must get into the bacteria, bind onto a target site, and accumulate in high concentrations inside the bacteria. Enzymes can work to inactivate the antibiotic.

• Bacteria can reduce permeability to antibiotics, reducing their accumulation inside the cell.

• Bacteria can push antibiotics out of the cell via increased efflux, reducing their accumulation inside the cell.

• Both mechanisms result in decreased amounts of antibiotic accumulating inside the cell.

Antibiotic Resistance Mechanisms

In this section, the speaker discusses the different mechanisms by which bacteria develop resistance to antibiotics.

Reducing Drug Accumulation Inside Bacterial Cells

• Certain bacteria have developed resistance to antibiotics by reducing their entry into the bacterial cell.

• Other bacteria have developed resistance to particular antibiotics by pushing them out of the cell.

Reducing Binding to Target Sites

• Some bacteria reduce the effectiveness of antibiotics through resistance mechanisms that reduce their binding to the actual target site.

• Particular bacteria have reduced or altered their target site, preventing the antibiotic from binding and exerting its effect on it.

Inactivation of Antibiotics

• Bacteria can produce enzymes that inactivate or destroy antibiotics, rendering them ineffective.

• Beta-lactamases are a classic example of enzymes that inactivate beta lactams, making them very susceptible to this type of resistance mechanism.

Antibiotic Resistance Mechanisms Summary

The three main mechanisms by which bacteria develop resistance to antibiotics are:

1. Reducing drug accumulation inside bacterial cells

2. Reducing binding to target sites

3. Inactivation of antibiotics through enzyme production.

Remembering certain groups of antibiotics associated with each mechanism can help recall these concepts more easily:

• Vat B: Vancomycin, Aminoglycosides, Tetracyclines (reduce drug accumulation inside bacterial cells)

• Fat M: Fluoroquinolones, Aminoglycosides, Tetracyclines (pushed out of bacterial cells)

• Fat BVM LT: Fluoroquinolones, Aminoglycosides, Tetracyclines (reduced binding to target sites), Macrolides, Linaiselid, Trimethoprim-sulfamethoxazole

• BAM: Beta-lactams, Aminoglycosides, Macrolides (inactivation of antibiotics through enzyme production)

Antibiotic Resistance Transmission Mechanisms

In this section, the speaker discusses the ways in which antibiotic resistance is transmitted between bacteria. The mechanisms of horizontal gene transfer are explained, including transformation, conjugation, and transduction. Additionally, vertical gene transfer through binary fission is discussed.

Horizontal Gene Transfer Mechanisms

• Three mechanisms of horizontal gene transfer are discussed: transformation, conjugation, and transduction.

• Transformation occurs when a bacterium takes up DNA or RNA from another bacterium that has been destroyed. This can lead to changes in permeability or target site of antibiotics.

• Conjugation involves the transfer of genetic material via a sex pilus and plasmids containing genes for antibiotic resistance.

• Transduction occurs when bacteriophages carry genetic material that encodes for antibiotic resistance.

Vertical Gene Transfer Mechanism

• Vertical gene transfer occurs through binary fission where daughter cells inherit genetic material from parent cells.

Risk Factors for Antibiotic Resistance

• Patients who get sick and go to hospitals are at risk for developing antibiotic-resistant infections due to exposure to other patients who may be carrying resistant bacteria.

Factors Contributing to Antibiotic Resistance

In this section, the speaker discusses various factors that contribute to antibiotic resistance.

Over-Prescription of Antibiotics

• Clinicians tend to over-prescribe antibiotics even when they are not necessary.

• This increases the opportunity for bacteria to become resistant to antibiotics.

• Preventing over-prescription is crucial in reducing antibiotic resistance.

Use of Antibiotics in Food Products

• Some meats are impregnated with antibiotics, which can lead to exposure and development of resistance in humans.

• Certain types of antibiotics used in food products can also contribute to antibiotic resistance.

Mechanisms of Antibiotic Resistance

• Bacteria can develop resistance through many different mechanisms.

• Identifying the best antibiotic for a specific pathogen can be challenging due to potential development of resistance.

Methods for Determining Antibiotic Susceptibility

• Culturing samples from infected areas such as sputum, skin, urine or blood is crucial in determining the best antibiotic treatment.

• Once cultures are obtained, clinicians can determine which antibiotics are most effective against the specific pathogen.

Antibiotic Susceptibility Testing

In this section, the speaker discusses how to determine which antibiotics are best suited for treating a particular bacterial infection. They explain different methods of antibiotic susceptibility testing and how they can be used to determine the minimum inhibitory concentration (MIC) of a drug needed to kill a specific bacteria.

Methods of Antibiotic Susceptibility Testing

• There are several methods of antibiotic susceptibility testing, including broth microdilution, macrodilution, and the Kirby-Bauer method.

• The Kirby-Bauer method involves introducing antibiotics onto bacteria and observing how much bacteria dies around each antibiotic. This determines the MIC.

• These methods help determine which types of bacteria are susceptible to specific antibiotics that would cover it.

Choosing the Best Antibiotic

• When choosing an antibiotic, it is important to consider which one will cover the bacteria very well.

• If a patient has been started on antibiotics but their sputum culture comes back with klebsiella pneumonia, it is necessary to figure out which antibiotic would be best suited for treating this particular infection.

• Based on susceptibility testing results obtained through microdilution, macrodilution or Kirby Bauer method, some antibiotics may be resistant or intermediate in coverage. It is important not to give these drugs as they won't work effectively against the infection.

Antibiotics for Community-Acquired Pneumonia

In this section, the speaker discusses the appropriate antibiotics to use for community-acquired pneumonia.

Antibiotic Options

• Choose an antibiotic with narrow coverage to avoid broad coverage.

• Ceftriaxone is a good choice as it is not too broad and covers strep pneumo and atypicals.

• The speaker recommends ceftriaxone, piperacillin-tazobactam, or meropenem based on susceptibility testing of Klebsiella pneumonia grown from sputum culture.

Case Study: 65-Year-Old Male with Community-Acquired Pneumonia

• A 65-year-old male with myasthenia gravis and recent steroid use presents to the ED with fever, shortness of breath, productive cough, leukocytosis, and a right lower lobe infiltrate on chest x-ray.

• The patient likely has community-acquired pneumonia caused by strep pneumo or atypicals.

• Empiric treatment options include ceftriaxone plus a macrolide or doxycycline or monotherapy fluoroquinolone like moxifloxacin.

• Once cultures are obtained, the antibiotic regimen can be modified based on pathogen identification.

• Other potential treatment options include first/third-gen cephs, clindamycin, and high-dose amoxicillin. However, these may have adverse effects in patients with myasthenia gravis.

Conclusion

• The appropriate antibiotic for community-acquired pneumonia depends on the suspected pathogen and susceptibility testing.

• Empiric treatment options include ceftriaxone plus a macrolide or doxycycline or monotherapy fluoroquinolone like moxifloxacin.

• Once cultures are obtained, the antibiotic regimen can be modified based on pathogen identification.

• It is important to consider adverse effects and contraindications when prescribing antibiotics.

Considerations for Fluoroquinolones and Bacterial Resistance

In this section, the speaker discusses the potential contraindications of fluoroquinolones and the mechanisms by which bacteria develop resistance to them.

Contraindications of Fluoroquinolones

• Fluoroquinolones can exacerbate myasthenia gravis, making it a potential contraindication.

• They also have a high risk of causing tendon rupture in patients over 60 years old who are on steroids.

• Other considerations include prolonging QT interval, causing CYP450 inhibition, and increasing the risk of C. diff infection and hyper/hypoglycemia.

Mechanisms of Bacterial Resistance to Fluoroquinolones

• Bacteria can develop resistance through decreased permeability, efflux pumps, altering target sites, or creating inactivating enzymes.

• The acronym FAT MLT (or BVMLT if F is not present) can help remember these mechanisms.

• These mechanisms reduce the effectiveness and efficacy of fluoroquinolones.

Empiric Antibiotic Coverage for Pyelonephritis

In this section, the speaker discusses empiric antibiotic coverage options for pyelonephritis and how to choose antibiotics based on urine culture results.

Empiric Antibiotic Coverage Options for Pyelonephritis

• For empiric antibiotic coverage of pyelonephritis, options include ceftriaxone, fluoroquinolones, aminoglycosides, and amino penicillins.

• Ampicillin is preferred over amoxicillin due to better penetration.

• Urine cultures should be obtained to ensure correct bacteria coverage.

Choosing Antibiotics Based on Urine Culture Results

• If urine culture results show enterococcus, amino penicillins are the best option for coverage.

• Nitrofurantoin is better for cystitis, and vancomycin is another option for resistant strains.

Potential Side Effects of Ampicillin

• Acute interstitial nephritis, pancytopenia, rash, hypersensitivity reactions, and neurotoxicity are potential side effects of ampicillin.

Mechanism of Action and Resistance of Amino Penicillins

In this section, the speaker discusses the mechanism of action and resistance of amino penicillins.

Mechanism of Action of Amino Penicillins

• Amino penicillins work against the cell wall by reducing cross-linking and preventing cell wall synthesis.

Mechanisms of Bacterial Resistance to Amino Penicillins

• Bacteria can develop resistance through beta-lactamase production or altered target sites.

Antibiotic Resistance Mechanisms

In this section, the speaker discusses antibiotic resistance mechanisms and how to combat them.

Beta-lactamases

• Beta-lactamases break down the beta-lactam ring in amino penicillin, rendering it ineffective.

• To combat beta-lactamases, beta-lactamase inhibitors such as clavulonate can be added to amino penicillins to make them more effective.

• Other combinations include sulbactum with ampicillin, piperacillin with tazobactam, and avibactum with ceftazidime.

Empiric Coverage for Cellulitis

• For outpatient cellulitis that is not septic appearing or diffuse, empiric coverage for methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus A is recommended.

• Anti-staphylococcal penicillins like dicloxacillin and first-generation cephalosporins like cephalexin are primary options for MRSA and Streptococcus A coverage.

• If the patient's condition worsens after a few days of treatment with these antibiotics, other options include trimethoprim sulfamethoxazole, doxycycline, linaselid, or clindamycin.

Antibiotics by Mechanism of Action

In this section, the speaker discusses antibiotics by mechanism of action.

Cephalosporins

• Cephalosporins are a type of beta-lactam antibiotic that can be divided into generations based on their spectrum of activity.

• First-generation cephalosporins like cefazolin and cephalexin are effective against gram-positive bacteria, while later generations have broader spectra of activity.

Macrolides

• Macrolides like azithromycin and clarithromycin inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit.

• They are effective against gram-positive bacteria, some atypical pathogens, and some gram-negative bacteria.

Aminoglycosides

• Aminoglycosides like gentamicin and tobramycin inhibit bacterial protein synthesis by binding to the 30S ribosomal subunit.

• They are effective against gram-negative bacteria but not against anaerobes or most gram-positive bacteria.

Fluoroquinolones

• Fluoroquinolones like ciprofloxacin and levofloxacin inhibit bacterial DNA synthesis by targeting DNA gyrase and topoisomerase IV.

• They have broad-spectrum activity against both gram-negative and gram-positive bacteria but should be used with caution due to potential side effects.

Antibiotics and Resistant Bacteria

In this section, the speaker discusses antibiotics and resistant bacteria. They cover different antibiotics that can be used for MRSA coverage, adverse effects of these drugs, and mechanisms by which bacteria become resistant to particular antibiotics such as vancomycin.

Antibiotics for MRSA Coverage

• Trimethoprim sulfoxazole is a drug that can be used for MRSA coverage.

• If the infection worsens despite being on trimethoprim sulfoxazole, IV antibiotics may be required.

• Vancomycin is a good antibiotic option in this situation.

Adverse Effects of Antibiotics

• Adverse effects of trimethoprim sulfamethoxazole include pancytopenia, hemolytic anemia (especially in those with G6PDH deficiency), acute interstitial nephritis, teratogenicity, increased unconjugated bilirubin leading to kernicterus in babies, CYP450 inhibition causing phototoxicity and hyperkalemia.

• Adverse effects of vancomycin include nephrotoxicity (especially if super therapeutic), ototoxicity (especially when combined with an aminoglycoside), phlebitis upon infusion, red man syndrome upon rapid infusion causing rash, muscle spasm itching paritis hypotension tachycardia.

• Dress syndrome can also occur with some antibiotics.

Mechanisms of Resistance

• Bacteria become resistant to particular antibiotics such as vancomycin through mechanisms like decreasing permeability or altering target binding sites.

• Vancomycin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus are examples of bacteria that have developed resistance to vancomycin.

Antibiotics for Hospital-Acquired Pneumonia

• For a patient with hospital-acquired pneumonia, the two pathogens to consider are MRSA and Pseudomonas aeruginosa.

• Vancomycin or linezolid can be used for MRSA coverage, while ceftazidime, cefepime, piperacillin-tazobactam, and polymyxins are options for Pseudomonas coverage.

• Other antibiotics like trimethoprim-sulfamethoxazole, metronidazole, nitrofurantoin, fluoroquinolones (for double coverage), macrolides, clindamycin, linazolid and chloramphenicol do not cover Pseudomonas.

Treatment of Pneumonia and Adverse Effects

In this section, the speaker discusses the treatment of pneumonia using fluoroquinolones and polymixins. They also discuss the adverse effects of aminoglycosides.

Fluoroquinolones and Polymixins for Pneumonia Treatment

• Fluoroquinolones should only be used as double coverage, not as monotherapy.

• Polymixins are used as salvage therapy when other treatments fail.

• Vancomycin is used to treat pseudomonas in pneumonia patients.

Adverse Effects of Aminoglycosides

• Aminoglycosides can cause nephrotoxicity, ototoxicity, worsen myasthenia gravis, and are teratogenic.

• Bacteria develop resistance to aminoglycosides through various mechanisms.

Treatment of Septic Shock Patient

In this section, the speaker discusses the treatment of a patient with septic shock due to two bugs - MRSA and Pseudo. They also discuss which antibiotics are best suited for extended spectrum beta-lactamase klebsiella bacteria.

Treatment for Septic Shock Patient

• The patient is started on vancomycin and piperacillin-tazobactam for MRSA and Pseudo infections.

• Blood culture and sputum cultures are taken from the patient.

• Carbapenems, aminoglycosides, polymixins, and ceftazidime with avibactam are the antibiotics that cover extended spectrum beta-lactamase klebsiella bacteria.

• Carbapenems are the best option for treatment. Ceftazidime with avibactam can be considered if an infectious disease consultant is available.

Treatment of Hospital-Acquired Meningitis

In this section, the speaker discusses the treatment of hospital-acquired meningitis in a patient who developed it after an EVD was inserted.

Treatment Options for Meningitis

• If a patient develops meningitis after an EVD is inserted, vancomycin and cefepime or ceftazidime are good options to start with.

• If cultures reveal MRSA and Neisseria meningitidis, vancomycin should be continued for MRSA coverage while ceftriaxone can be used for Neisseria coverage.

Choosing Antibiotics

• Cefepime or ceftazidime are better options than percentage of bacterium because they have better central nervous system penetration.

• Third-generation cephalosporins like ceftriaxone are effective against Neisseria meningitidis.

Patient Case

• The patient needed an EVD due to a large bleed that caused increased pressure inside their skull.

• The blood started pushing into their ventricles, causing hydrocephalus.

• The patient developed hospital-acquired meningitis due to the EVD insertion.

• Cultures revealed MRSA and Neisseria meningitidis.