Podcast
Questions and Answers
What is the main function of the somatic nervous system?
What is the main function of the somatic nervous system?
- To transmit sensory information to the brain
- To regulate the body's skeletal muscles (correct)
- To control involuntary activities of visceral muscles
- To coordinate involuntary activities of internal organs and glands
Where is the cell body of the preganglionic neuron typically located in the autonomic nervous system?
Where is the cell body of the preganglionic neuron typically located in the autonomic nervous system?
- In the peripherals of the nervous system
- In the somatic nervous system
- In the autonomic ganglion
- In the lateral horn of the gray matter of the spinal cord or in the brainstem (correct)
Which division of the autonomic nervous system is characterized by preganglionic neurons located in the thoracic and lumbar regions of the spinal cord?
Which division of the autonomic nervous system is characterized by preganglionic neurons located in the thoracic and lumbar regions of the spinal cord?
- Sympathetic division (correct)
- Peripheral nervous system
- Somatic nervous system
- Parasympathetic division
What is the typical neurotransmitter released by sympathetic neurons?
What is the typical neurotransmitter released by sympathetic neurons?
Which type of neuron typically releases acetylcholine as its neurotransmitter in the autonomic nervous system?
Which type of neuron typically releases acetylcholine as its neurotransmitter in the autonomic nervous system?
What is a characteristic of the autonomic nervous system in relation to effector organs?
What is a characteristic of the autonomic nervous system in relation to effector organs?
What type of receptors are primarily activated by epinephrine at low doses?
What type of receptors are primarily activated by epinephrine at low doses?
What is the effect of the sympathetic nervous system on the bronchial tree?
What is the effect of the sympathetic nervous system on the bronchial tree?
What is the primary function of the adrenal medulla in response to sympathetic stimulation?
What is the primary function of the adrenal medulla in response to sympathetic stimulation?
What is the effect of norepinephrine on the heart?
What is the effect of norepinephrine on the heart?
What is the effect of dopamine on the kidneys?
What is the effect of dopamine on the kidneys?
Which nerve is parasympathetic to the heart?
Which nerve is parasympathetic to the heart?
What is the primary use of fenoldopam IV?
What is the primary use of fenoldopam IV?
What is the effect of epinephrine on blood pressure at high doses?
What is the effect of epinephrine on blood pressure at high doses?
What is the primary use of isoproterenol in patients with asthma?
What is the primary use of isoproterenol in patients with asthma?
What is the effect of the parasympathetic nervous system on the bronchial tree?
What is the effect of the parasympathetic nervous system on the bronchial tree?
What is the primary action of alpha adrenergic blockers on blood vessels?
What is the primary action of alpha adrenergic blockers on blood vessels?
Which drug is used to control episodes of hypertension in pheochromocytoma before surgery?
Which drug is used to control episodes of hypertension in pheochromocytoma before surgery?
What is the effect of activation of Alpha (α) 1 receptors?
What is the effect of activation of Alpha (α) 1 receptors?
Which drug is linked to intraoperative floppy iris syndrome (IFIS), a risk factor for complications during cataract surgery?
Which drug is linked to intraoperative floppy iris syndrome (IFIS), a risk factor for complications during cataract surgery?
What is the effect of Beta Blockers on the heart?
What is the effect of Beta Blockers on the heart?
Which drug can be used for in hypertensive emergency situations?
Which drug can be used for in hypertensive emergency situations?
What is the effect of Guanethidine on the peripheral nervous system?
What is the effect of Guanethidine on the peripheral nervous system?
Which drug is used to primarily improve muscle function in individuals with Myasthenia Gravis?
Which drug is used to primarily improve muscle function in individuals with Myasthenia Gravis?
What is the effect of Reserpine on neurotransmitters?
What is the effect of Reserpine on neurotransmitters?
Which neurotransmitter is responsible for the action of constricting the pupil via parasympathetic innervation in the Iris Sphincter?
Which neurotransmitter is responsible for the action of constricting the pupil via parasympathetic innervation in the Iris Sphincter?
What is the effect of alpha 2 activation on aqueous humor production?
What is the effect of alpha 2 activation on aqueous humor production?
Which medication is commonly used to treat open-angle glaucoma by inducing miosis and enhancing accommodation?
Which medication is commonly used to treat open-angle glaucoma by inducing miosis and enhancing accommodation?
What is the therapeutic use of Echothiophate?
What is the therapeutic use of Echothiophate?
Which medication is used to differentiate between second and third neuron involvement in Horner's Syndrome?
Which medication is used to differentiate between second and third neuron involvement in Horner's Syndrome?
What is the effect of beta blockers on aqueous humor production?
What is the effect of beta blockers on aqueous humor production?
Which medication is commonly used to treat dry eyes and mouth in patients with Sjogren's syndrome?
Which medication is commonly used to treat dry eyes and mouth in patients with Sjogren's syndrome?
What is the antidote for tubocurarine and neuromuscular blockers?
What is the antidote for tubocurarine and neuromuscular blockers?
What is the therapeutic use of Pralidoxime?
What is the therapeutic use of Pralidoxime?
Which medication is a cardio-selective beta blocker?
Which medication is a cardio-selective beta blocker?
What is the effect of acetylcholine on muscarinic receptors?
What is the effect of acetylcholine on muscarinic receptors?
What is the antidote for organophosphate intoxication, particularly from insecticides?
What is the antidote for organophosphate intoxication, particularly from insecticides?
What is the mechanism of action of Ipratropium?
What is the mechanism of action of Ipratropium?
What medication is used to treat dystonia in patients undergoing treatment with antipsychotic medications?
What medication is used to treat dystonia in patients undergoing treatment with antipsychotic medications?
Which medication is used in emergency situations to lower blood pressure?
Which medication is used in emergency situations to lower blood pressure?
What is the medication of choice for rapid endotracheal intubation during anesthesia induction?
What is the medication of choice for rapid endotracheal intubation during anesthesia induction?
What type of receptors do ganglionic blockers act on?
What type of receptors do ganglionic blockers act on?
Which medication is used as an alternative in cycloplegic refraction, especially when accommodative esotropia is involved?
Which medication is used as an alternative in cycloplegic refraction, especially when accommodative esotropia is involved?
What is a prolonged asthma attack that doesn't respond to typical drug therapy?
What is a prolonged asthma attack that doesn't respond to typical drug therapy?
What is the antidote for atropine overdose?
What is the antidote for atropine overdose?
What is the lethal dose of atropine in children?
What is the lethal dose of atropine in children?
What is the mechanism of action of Bacitracin?
What is the mechanism of action of Bacitracin?
What type of spectrum does Bacitracin have?
What type of spectrum does Bacitracin have?
What is the warning associated with systemic use of Bacitracin?
What is the warning associated with systemic use of Bacitracin?
What is the mechanism of action of Erythromycin?
What is the mechanism of action of Erythromycin?
What is the treatment of choice for external hordeolum?
What is the treatment of choice for external hordeolum?
What is a characteristic feature of the infiltrate associated with Pseudomonas infections?
What is a characteristic feature of the infiltrate associated with Pseudomonas infections?
What is a concerning complication of Pseudomonas keratitis?
What is a concerning complication of Pseudomonas keratitis?
What is a characteristic of Pseudomonas keratitis?
What is a characteristic of Pseudomonas keratitis?
What is the location of the infection in Pseudomonas keratitis?
What is the location of the infection in Pseudomonas keratitis?
What is often seen in Pseudomonas keratitis?
What is often seen in Pseudomonas keratitis?
What is the mechanism of action of polymyxin B?
What is the mechanism of action of polymyxin B?
What is the primary target of dicloxacillin in bacterial cell walls?
What is the primary target of dicloxacillin in bacterial cell walls?
What is the main adverse effect of cephalexin in individuals with impaired kidney function?
What is the main adverse effect of cephalexin in individuals with impaired kidney function?
What is the mechanism of action of cephalexin in bacterial cells?
What is the mechanism of action of cephalexin in bacterial cells?
What is the class of antibiotics that may be considered for internal hordeolum if a patient has allergies to penicillin or cephalosporin?
What is the class of antibiotics that may be considered for internal hordeolum if a patient has allergies to penicillin or cephalosporin?
What is the primary indication for the use of levofloxacin in ophthalmology?
What is the primary indication for the use of levofloxacin in ophthalmology?
What is the primary mechanism of action of aminoglycosides in bacterial cells?
What is the primary mechanism of action of aminoglycosides in bacterial cells?
What is the limitation of using aminoglycosides in acute bacterial conjunctivitis?
What is the limitation of using aminoglycosides in acute bacterial conjunctivitis?
What is the mechanism of action of bacitracin ointment in bacterial cells?
What is the mechanism of action of bacitracin ointment in bacterial cells?
What is the primary use of fluoroquinolones in ophthalmology?
What is the primary use of fluoroquinolones in ophthalmology?
What is a characteristic of Chlamydia trachomatis?
What is a characteristic of Chlamydia trachomatis?
What is the difference between trachoma and inclusion conjunctivitis?
What is the difference between trachoma and inclusion conjunctivitis?
What is the sequela of trachoma if left untreated?
What is the sequela of trachoma if left untreated?
What is the stage of trachoma characterized by the extension of follicles beyond the superior limbus into Herbert pits?
What is the stage of trachoma characterized by the extension of follicles beyond the superior limbus into Herbert pits?
What is the characteristic feature of trachoma stage IV?
What is the characteristic feature of trachoma stage IV?
What is the most common bacterium causing keratitis in contact lens wearers?
What is the most common bacterium causing keratitis in contact lens wearers?
What is the characteristic feature of an ulcer caused by Streptococcus pneumoniae?
What is the characteristic feature of an ulcer caused by Streptococcus pneumoniae?
What is the characteristic feature of an ulcer caused by Staphylococcus pneumoniae?
What is the characteristic feature of an ulcer caused by Staphylococcus pneumoniae?
What is the effect of Chlamydia infection on the eye?
What is the effect of Chlamydia infection on the eye?
What is the sequela of untreated Chlamydia infection?
What is the sequela of untreated Chlamydia infection?
What is the mechanism of action of Bacitracin?
What is the mechanism of action of Bacitracin?
What is the primary indication for the use of fluoroquinolones in ophthalmology?
What is the primary indication for the use of fluoroquinolones in ophthalmology?
What is the effect of Bacitracin on bacterial cells?
What is the effect of Bacitracin on bacterial cells?
What is the primary difference between Meibomian Seborrhea and Meibomianitis?
What is the primary difference between Meibomian Seborrhea and Meibomianitis?
What is the typical color of the infiltrate associated with Pseudomonas infections?
What is the typical color of the infiltrate associated with Pseudomonas infections?
What is usually seen in conjunction with the infiltrate in Pseudomonas keratitis?
What is usually seen in conjunction with the infiltrate in Pseudomonas keratitis?
What is the rapid progression of Pseudomonas keratitis likely to lead to?
What is the rapid progression of Pseudomonas keratitis likely to lead to?
What is the primary difference between Chlamydia trachomatis serotypes D to K and serotypes A, B, Ba, and C?
What is the primary difference between Chlamydia trachomatis serotypes D to K and serotypes A, B, Ba, and C?
What is the characteristic feature of an ulcer caused by Streptococcus pneumoniae?
What is the characteristic feature of an ulcer caused by Streptococcus pneumoniae?
What is the main mechanism of action of Polymyxin B?
What is the main mechanism of action of Polymyxin B?
What is the most common bacterium causing keratitis in contact lens wearers?
What is the most common bacterium causing keratitis in contact lens wearers?
What is the primary effect of Dicloxacillin on bacterial cells?
What is the primary effect of Dicloxacillin on bacterial cells?
What is the effect of untreated trachoma?
What is the effect of untreated trachoma?
What is the characteristic feature of Pseudomonas keratitis?
What is the characteristic feature of Pseudomonas keratitis?
What is the primary use of Cephalexin?
What is the primary use of Cephalexin?
What is the stage of trachoma characterized by the development of conjunctival scarring?
What is the stage of trachoma characterized by the development of conjunctival scarring?
What is the common adverse effect of Cephalexin and Dicloxacillin?
What is the common adverse effect of Cephalexin and Dicloxacillin?
What is the effect of Neomycin on the eye?
What is the effect of Neomycin on the eye?
What is the alternative antibiotic to Cephalexin for internal hordeolum treatment?
What is the alternative antibiotic to Cephalexin for internal hordeolum treatment?
What is the primary difference between inclusion conjunctivitis and trachoma?
What is the primary difference between inclusion conjunctivitis and trachoma?
What is the primary use of Levofloxacin in ophthalmology?
What is the primary use of Levofloxacin in ophthalmology?
What is the effect of untreated Chlamydia infection?
What is the effect of untreated Chlamydia infection?
What is the limitation of using Aminoglycosides for acute bacterial conjunctivitis?
What is the limitation of using Aminoglycosides for acute bacterial conjunctivitis?
What is the primary mechanism of action of Bacitracin ointment?
What is the primary mechanism of action of Bacitracin ointment?
What is the primary characteristic of trachoma stage IV?
What is the primary characteristic of trachoma stage IV?
What is the primary use of Polymyxin B/Bacitracin ointment?
What is the primary use of Polymyxin B/Bacitracin ointment?
What is the primary target of Dicloxacillin in bacterial cell walls?
What is the primary target of Dicloxacillin in bacterial cell walls?
What is the primary mechanism of action of calcium carbonate?
What is the primary mechanism of action of calcium carbonate?
Which antibiotic subclass exhibits concentration-dependent killing?
Which antibiotic subclass exhibits concentration-dependent killing?
What is the characteristic of time-dependent killing antibiotics?
What is the characteristic of time-dependent killing antibiotics?
What is the effect of sodium bicarbonate on stomach acid?
What is the effect of sodium bicarbonate on stomach acid?
Which of the following is NOT true regarding Minimum Inhibitory Concentrations (MICs)?
Which of the following is NOT true regarding Minimum Inhibitory Concentrations (MICs)?
What is the primary use of calcium carbonate?
What is the primary use of calcium carbonate?
What is the primary goal of determining the minimum inhibitory concentration (MIC) of an antimicrobial?
What is the primary goal of determining the minimum inhibitory concentration (MIC) of an antimicrobial?
Which type of antibiotic is most effective when its concentration is maintained above the MIC for as long as possible?
Which type of antibiotic is most effective when its concentration is maintained above the MIC for as long as possible?
What is the primary goal of pulsed dosing in antimicrobial therapy?
What is the primary goal of pulsed dosing in antimicrobial therapy?
Which type of antibiotic is effective against a wide variety of microbial species?
Which type of antibiotic is effective against a wide variety of microbial species?
What is the primary characteristic of narrow-spectrum antibiotics?
What is the primary characteristic of narrow-spectrum antibiotics?
Which type of antibiotic is known to cause ototoxicity?
Which type of antibiotic is known to cause ototoxicity?
Which type of antibiotic is most effective when its concentration is higher, rather than when it stays in the body for a longer period?
Which type of antibiotic is most effective when its concentration is higher, rather than when it stays in the body for a longer period?
Which antibiotic is commonly associated with hypersensitivity reactions?
Which antibiotic is commonly associated with hypersensitivity reactions?
What is the primary benefit of using pulsed dosing in antimicrobial therapy?
What is the primary benefit of using pulsed dosing in antimicrobial therapy?
What is the primary difference between time-dependent and concentration-dependent antibiotics?
What is the primary difference between time-dependent and concentration-dependent antibiotics?
Which category describes antibiotics derived from natural sources but chemically modified in the laboratory?
Which category describes antibiotics derived from natural sources but chemically modified in the laboratory?
What is the mechanism of action of β-lactam antibiotics?
What is the mechanism of action of β-lactam antibiotics?
Which type of antibiotic is effective against both gram-positive and gram-negative bacteria?
Which type of antibiotic is effective against both gram-positive and gram-negative bacteria?
What is the primary advantage of using broad-spectrum antibiotics?
What is the primary advantage of using broad-spectrum antibiotics?
Which antibiotic class primarily exerts its bactericidal effect by inhibiting cell wall synthesis?
Which antibiotic class primarily exerts its bactericidal effect by inhibiting cell wall synthesis?
What is the mechanism of action of fluoroquinolones?
What is the mechanism of action of fluoroquinolones?
Are fluoroquinolones bactericidal or bacteriostatic?
Are fluoroquinolones bactericidal or bacteriostatic?
Which antibiotic is commonly associated with broad-spectrum activity?
Which antibiotic is commonly associated with broad-spectrum activity?
How does metronidazole primarily exert its bactericidal effect?
How does metronidazole primarily exert its bactericidal effect?
What is the parent drug of the quinolone antibiotic class?
What is the parent drug of the quinolone antibiotic class?
What is the primary reason why drug combination therapy is used instead of using a single antibiotic?
What is the primary reason why drug combination therapy is used instead of using a single antibiotic?
What is the mechanism of antibiotic resistance that involves modifying the target site of antibiotics?
What is the mechanism of antibiotic resistance that involves modifying the target site of antibiotics?
What is the term used to describe the enhanced effectiveness of antibiotics when used in combination?
What is the term used to describe the enhanced effectiveness of antibiotics when used in combination?
What is the primary disadvantage of using bacteriostatic agents in combination with other antibiotics?
What is the primary disadvantage of using bacteriostatic agents in combination with other antibiotics?
What is the term used to describe the ability of antibiotics to target a wide range of bacterial species?
What is the term used to describe the ability of antibiotics to target a wide range of bacterial species?
What is the mechanism of antibiotic resistance that involves the production of enzymes that can degrade antibiotics?
What is the mechanism of antibiotic resistance that involves the production of enzymes that can degrade antibiotics?
What is the primary advantage of using extended-spectrum antibiotics?
What is the primary advantage of using extended-spectrum antibiotics?
What is the mechanism of antibiotic resistance that involves the transfer of genes encoding antibiotic resistance from one bacterium to another?
What is the mechanism of antibiotic resistance that involves the transfer of genes encoding antibiotic resistance from one bacterium to another?
What is the primary disadvantage of using drug combination therapy?
What is the primary disadvantage of using drug combination therapy?
What is the term used to describe the ability of antibiotics to target a specific range of bacterial species?
What is the term used to describe the ability of antibiotics to target a specific range of bacterial species?
What is the primary mechanism of action of tetracyclines?
What is the primary mechanism of action of tetracyclines?
Which of the following antibiotics is characterized by higher absorption, less food interference, and less protein binding?
Which of the following antibiotics is characterized by higher absorption, less food interference, and less protein binding?
What is the common adverse effect associated with tetracycline use in children under 12 years old?
What is the common adverse effect associated with tetracycline use in children under 12 years old?
What is the mechanism of action of linezolid?
What is the mechanism of action of linezolid?
Which of the following antibiotic classes is effective against Gram-negative bacteria?
Which of the following antibiotic classes is effective against Gram-negative bacteria?
What is the effect of combining β-lactam antibiotics and aminoglycosides?
What is the effect of combining β-lactam antibiotics and aminoglycosides?
How are aminoglycosides typically administered systemically?
How are aminoglycosides typically administered systemically?
What is the primary mechanism of action of beta-lactam antibiotics?
What is the primary mechanism of action of beta-lactam antibiotics?
What is the common adverse effect of clindamycin?
What is the common adverse effect of clindamycin?
Which antibiotic is effective against protozoans such as Trichomonas vaginalis?
Which antibiotic is effective against protozoans such as Trichomonas vaginalis?
Which medication would you prescribe to alleviate nausea and vomiting in a chemotherapy patient?
Which medication would you prescribe to alleviate nausea and vomiting in a chemotherapy patient?
What type of bacteria is Clostridium difficile?
What type of bacteria is Clostridium difficile?
What is the primary advantage of using aminosalicylates in patients with IBD?
What is the primary advantage of using aminosalicylates in patients with IBD?
What is the primary mechanism of action of Ondansetron and Granisetron in alleviating nausea and vomiting?
What is the primary mechanism of action of Ondansetron and Granisetron in alleviating nausea and vomiting?
What is the main reason aminoglycosides are reserved for severe systemic Gram-negative infections?
What is the main reason aminoglycosides are reserved for severe systemic Gram-negative infections?
Which condition is characterized by a feeling of incomplete emptying?
Which condition is characterized by a feeling of incomplete emptying?
What is the mechanism of action of tetracyclines?
What is the mechanism of action of tetracyclines?
What is the main precaution to be taken when using aminosalicylates in certain individuals?
What is the main precaution to be taken when using aminosalicylates in certain individuals?
Why is doxycycline contraindicated in pregnancy?
Why is doxycycline contraindicated in pregnancy?
What is the mechanism of action of sulfonamides?
What is the mechanism of action of sulfonamides?
What is the mechanism of action of trimethoprim-sulfamethoxazole?
What is the mechanism of action of trimethoprim-sulfamethoxazole?
Which antibiotic targets the intermediary metabolic pathway for the synthesis of tetrahydrofolic acid?
Which antibiotic targets the intermediary metabolic pathway for the synthesis of tetrahydrofolic acid?
What is the mechanism of action of beta-lactams?
What is the mechanism of action of beta-lactams?
What is the mechanism of action of aminoglycosides?
What is the mechanism of action of aminoglycosides?
What is the mechanism of action of tetracyclines?
What is the mechanism of action of tetracyclines?
What is the mechanism of action of fluoroquinolones?
What is the mechanism of action of fluoroquinolones?
Which enzyme does sulfonamides inhibit by competing with}
Which enzyme does sulfonamides inhibit by competing with}
What is the primary mechanism of action of rifamycins in bacteria?
What is the primary mechanism of action of rifamycins in bacteria?
What is the primary effect of corticosteroids on the immune system?
What is the primary effect of corticosteroids on the immune system?
What is the primary use of thiopurines in the treatment of inflammatory bowel diseases?
What is the primary use of thiopurines in the treatment of inflammatory bowel diseases?
Which medication works by inhibiting ribonucleotide synthesis, leading to the induction of apoptosis in T cells?
Which medication works by inhibiting ribonucleotide synthesis, leading to the induction of apoptosis in T cells?
What is the primary mechanism of action of lincosamides in bacteria?
What is the primary mechanism of action of lincosamides in bacteria?
What is the primary effect of oxazolidinones on bacterial protein synthesis?
What is the primary effect of oxazolidinones on bacterial protein synthesis?
Which medication is used to treat conditions where there is excessive cell growth or immune activity, such as certain types of cancer and autoimmune diseases?
Which medication is used to treat conditions where there is excessive cell growth or immune activity, such as certain types of cancer and autoimmune diseases?
What is the primary side effect of thiopurines that patients are often advised to monitor for?
What is the primary side effect of thiopurines that patients are often advised to monitor for?
Which medication works by deactivating key processes in T lymphocytes?
Which medication works by deactivating key processes in T lymphocytes?
What is the primary mechanism of action of methotrexate in treating Crohn's disease?
What is the primary mechanism of action of methotrexate in treating Crohn's disease?
What is the mechanism of action of simethicone?
What is the mechanism of action of simethicone?
Which area of the brainstem is responsible for controlling emesis?
Which area of the brainstem is responsible for controlling emesis?
Which medication is commonly used for vestibular-related conditions such as motion sickness and BPPV?
Which medication is commonly used for vestibular-related conditions such as motion sickness and BPPV?
What is the mechanism of action of promethazine?
What is the mechanism of action of promethazine?
Which medication should be avoided in patients with Parkinson's disease?
Which medication should be avoided in patients with Parkinson's disease?
What is the effect of scopolamine on muscarinic receptors?
What is the effect of scopolamine on muscarinic receptors?
What is the primary mechanism of action of simethicone in alleviating discomfort from excess gas?
What is the primary mechanism of action of simethicone in alleviating discomfort from excess gas?
Which medication is used to alleviate symptoms of nausea and vomiting by blocking dopamine receptors?
Which medication is used to alleviate symptoms of nausea and vomiting by blocking dopamine receptors?
What is the primary site of action for emesis stimulation?
What is the primary site of action for emesis stimulation?
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Study Notes
Bacterial Keratitis
- Caused by bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae
- Pseudomonas aeruginosa:
- Infiltrate is gray in color
- Central location of infection
- Overlying epithelial defect, indicating damage to the outer layer of the cornea
- Rapid progression, potentially leading to ring ulcer formation
- Corneal perforation possible within 24-48 hours if left untreated
- Staphylococcus aureus:
- Infiltrate is well-defined, white-grey, or creamy in color
- Less common to have uveitis and hypopyon compared to Streptococcus pneumoniae infections
- Streptococcus pneumoniae:
- Ulcer appears gray-yellow in color with a disc-like shape
- Infections often cause severe inflammation within the eye, known as uveitis
- Presence of hypopyon, a collection of white blood cells in the anterior chamber of the eye
Bacterial Blepharitis
- Caused by Staphylococcus aureus and S. epidermidis
- Drug of choice: Bacitracin
- Prevents the formation of bacterial cell walls, making bacteria vulnerable and killing them
- Narrow-spectrum antibiotic, effective against gram-positive and Neisseriae
- Can cause renal toxicity when used systemically
- Alternative treatment: Erythromycin
- Macrolide antibacterial
- Inhibits bacterial protein synthesis
- Bacteriostatic
Meibomian Gland Dysfunction (MGD)
- Dysfunctional meibomian glands
- Meibomian Seborrhea: excessive production of sebum (oil) by the meibomian glands
- Meibomianitis (or Meibomitis): inflammation of the meibomian glands
- Can occur due to various factors
Chlamydial Conjunctivitis
- Caused by Chlamydia trachomatis
- Infection presents unilaterally or bilaterally, often associated with sexually transmitted infections
- Serotypes D to K:
- Cause inclusion conjunctivitis, often affecting adults
- Serotypes A, B, Ba, and C:
- Cause trachoma, a chronic inflammatory disease of the eye
- Predominantly affects underprivileged populations in certain regions
- Can lead to severe complications if left untreated
- One of the leading causes of preventable blindness worldwide
- Stages of trachoma:
- Inflammation of the conjunctiva with follicle formation, mild corneal changes, and purulent discharge
- Increased inflammation, maturation of follicles, and possible presence of subepithelial infiltrates and limbal follicles
- Extension of follicles beyond the superior limbus into Herbert pits and development of conjunctival scarring (Arlt's line)
- Severe and advanced form with extensive scarring, absence of follicles on the upper tarsus, corneal pannus, and significant ocular complications
External Hordeolum
- Caused by Staphylococcus aureus
- Presents unilaterally or bilaterally
- Treatment: Bacitracin ointment or Polymyxin B/Bacitracin ointment
- Effective against gram-negative organisms like Pseudomonas or Haemophilus
Internal Hordeolum
- Caused by Staphylococcus bacteria
- Develops if someone already has eyelid inflammation, like blepharitis or meibomianitis
- Left untreated may result in preseptal or orbital cellulitis
- Treatment:
- Dicloxacillin:
- Disrupts bacterial cell walls, causing them to break apart and die
- Excreted through urine, dosage adjustments necessary for patients with low creatinine clearance
- Adverse effects: cross-sensitivity with cephalosporins, nephrotoxicity, and serum sickness
- Cephalexin:
- Bactericidal, causing defective peptidoglycan, weakening bacterial cell walls
- Excreted through urine, dosage adjustments necessary for patients with impaired kidney function
- Adverse effects: hypersensitivity reactions, nephrotoxicity, pseudomembranous colitis, and cross-sensitivity with penicillin
- Alternative antibiotics for patients allergic to penicillin or cephalosporins: Macrolides### Antibiotic Mechanisms of Action
- Dicloxacillin:
- Tetracyclines: inhibit protein synthesis by binding to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA molecules and inhibiting the elongation of the polypeptide chain
- Bacteriostatic
- Linezolid (Oxazolidinone): inhibits bacterial protein synthesis by blocking the formation of the 70S ribosomal initiation complex
- Bacteriostatic, but has some bactericidal activity against specific bacteria (e.g. Streptococci)
- Macrolides (e.g. Erythromycin, Clarithromycin, Azithromycin): inhibit protein synthesis by binding to the 50S ribosomal subunit
- Beta-lactams (e.g. Penicillins, Cephalosporins): disrupt bacterial cell wall synthesis, leading to cell death
- Bactericidal
- Aminoglycosides (e.g. Gentamicin, Tobramycin, Amikacin): interfere with bacterial protein synthesis
- Bactericidal, exhibit concentration-dependent killing
- Fluoroquinolones (e.g. Ciprofloxacin, Norfloxacin, Levofloxacin): target bacterial DNA gyrase and topoisomerase IV, disrupting DNA replication and cell division
- Bactericidal, exhibit broad-spectrum activity
- Metronidazole: causes damage to bacterial DNA
- Bactericidal, effective against Protozoa (e.g. Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis)
Antibiotic Resistance Mechanisms
- Genetic alteration: bacteria undergo genetic changes to develop resistance
- Transfer of drug resistance by R factors (plasmids): bacteria acquire genes encoding antibiotic resistance from other bacteria
- Modification of target site: bacteria modify the target site of antibiotics, making them less effective
- Decreased accumulation: bacteria reduce the accumulation of antibiotics inside their cells
- Enzymatic inactivation: bacteria produce enzymes that chemically modify or degrade antibiotics
Drug Combination Therapy
- Advantages: synergism, preventing resistance, treating mixed infections
- Disadvantages: growth-dependent effectiveness, potential interactions between antibiotics
Other
- Minimum Inhibitory Concentrations (MICs): the lowest concentration of an antimicrobial that inhibits the visible growth of a microorganism
- Pulsed dosing: administering high doses of antibiotics followed by a prolonged dose-free period to achieve therapeutic concentrations and prevent toxicity
- Narrow-spectrum antibiotics: effective against a single or limited group of organisms
- Broad-spectrum antibiotics: effective against a wide range of microbial species
- Extended-spectrum antibiotics: effective against a wide range of bacteria, including both Gram-positive and Gram-negative species### Antibiotics and Bacterial Infections
- Aminoglycosides are not administered orally due to poor gastrointestinal absorption. Instead, they are given intravenously or intramuscularly.
- Aminoglycosides are reserved for severe systemic Gram-negative infections due to their potential for adverse effects such as nephrotoxicity and ototoxicity.
- The mechanism of action of tetracyclines involves the inhibition of protein synthesis by binding to the 30S ribosomal subunit, preventing the initiation of translation.
Sulfonamides and Folic Acid Synthesis
- Sulfonamides inhibit bacterial folic acid synthesis by competing with para-aminobenzoic acid (PABA), which is necessary for folic acid production.
- Trimethoprim inhibits dihydrofolate reductase, disrupting folic acid synthesis.
- Trimethoprim/Sulfamethoxazole (Bactrim) is used to treat a wide range of bacterial infections, including ear infections, urinary tract infections, bronchitis, and Pneumocystis jirovecii pneumonia.
Antibiotic Mechanisms of Action
- Beta-Lactams: Inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs).
- Aminoglycosides: Bind to the 30S ribosomal subunit, causing misreading of mRNA and inhibiting protein synthesis.
- Tetracyclines: Bind to the 30S ribosomal subunit, inhibiting protein synthesis by preventing the attachment of aminoacyl-tRNA to the mRNA-ribosome complex.
- Glycopeptides: Inhibit bacterial cell wall synthesis by binding to the (D-alanyl-D-alanine) peptide side chain.
- Macrolides: Bind to the 50S ribosomal subunit, inhibiting bacterial protein synthesis by blocking the translocation step during translation.
- Fluoroquinolones: Inhibit bacterial DNA gyrase and topoisomerase IV enzymes, essential for DNA replication, repair, and transcription.
- Sulfonamides: Inhibit bacterial folic acid synthesis by competitively inhibiting dihydropteroate synthase.
- Oxazolidinones: Bind to the 50S ribosomal subunit, preventing the formation of the initiation complex for protein synthesis.
- Lincosamides: Bind to the 50S ribosomal subunit, inhibiting protein synthesis by blocking the translocation step during translation.
- Rifamycins: Inhibit bacterial RNA synthesis by binding to the bacterial RNA polymerase.
Corticosteroids
- Mechanism of action: Decrease production of inflammatory molecules, suppress metabolism of arachidonic acid, induce apoptosis in certain immune cells, and promote production of anti-inflammatory proteins.
- Use: Manage inflammatory bowel diseases (IBD) like Crohn's disease and ulcerative colitis, reduce inflammation in the digestive tract.
Thiopurines
- Mechanism of action: Inhibit ribonucleotide synthesis, leading to apoptosis in T cells.
- Use: Treat active and chronic inflammatory conditions, particularly as steroid-sparing agents to reduce reliance on corticosteroids.
Methotrexate
- Mechanism of action: Inhibits dihydrofolate reductase, disrupting DNA and RNA synthesis.
- Use: Treat conditions with excessive cell growth or immune activity, such as certain types of cancer and autoimmune diseases like rheumatoid arthritis.
Simethicone
- Mechanism of action: Modifies the elasticity of mucus-coated gas bubbles, causing them to collapse and reducing gas accumulation.
- Use: Relieve discomfort from excess gas in the digestive tract.
Emesis (Vomiting)
- Pathophysiology: Controlled by the area postrema in the brainstem, which can be stimulated by signals from the stomach and gastrointestinal tract, vestibular system, and cortex and thalamus.
- Medications:
- Scopolamine: Blocks muscarinic M1 receptors, used to treat vestibular-related conditions like motion sickness and benign paroxysmal positional vertigo (BPPV).
- Promethazine: Acts as a dopamine D2 receptor antagonist and histamine H1 blocker, used to treat nausea and vomiting.
Adrenergic Agonists and Antagonists
- Epinephrine: Stimulates alpha and beta receptors, causing effects like increased heart rate, vasopressor response, and bronchodilation.
- Norepinephrine: Stimulates alpha receptors, causing vasoconstriction and increased blood pressure.
- Isoproterenol: Stimulates beta-1 and beta-2 receptors, causing increased heart rate and bronchodilation.
- Dopamine: Stimulates alpha-1 and beta-1 receptors, causing increased heart rate and vasopressor response.
Cholinergic System
- Muscarinic receptors: Found in the neuro-effector junction of the parasympathetic nervous system, heart, smooth muscle, and brain.
- Nicotinic receptors: Found in the neuro-effector junction of the parasympathetic nervous system, skeletal muscle, and brain.
- Acetylcholine: Released by the parasympathetic nervous system, causes muscarinic and nicotinic effects.
- Bethanechol: Stimulates muscarinic receptors, used to promote urination.
- Carbachol: Exhibits both muscarinic and nicotinic actions.
- Pilocarpine: Stimulates muscarinic receptors, used to treat open-angle glaucoma.
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