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ANTIMICROBIAL & ANTIVIRAL DRUGS — Exam Answers

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Q1. Classification of Antibiotics by Mechanism of Action

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Q2. Bacterial Resistance to Antibiotics

Mechanisms of Resistance:

1. Enzymatic inactivation - Beta-lactamases destroy beta-lactam ring; acetyltransferases inactivate aminoglycosides
2. Altered target site - Modified PBPs (MRSA); altered 23S rRNA (macrolide resistance)
3. Reduced permeability - Loss of outer membrane porins in gram-negative bacteria
4. Efflux pumps - Active transport of drug out of the cell (tetracyclines, fluoroquinolones)
5. Bypass pathways - Bacteria acquire alternative metabolic routes (e.g., MRSA acquires mecA gene)

Types:

• Intrinsic resistance - Natural, always present (e.g., gram-negatives to vancomycin)
• Acquired resistance - Via mutation or horizontal gene transfer (plasmids, transposons)

Control & Prevention:

• Rational antibiotic prescribing (avoid overuse/misuse)
• Use narrow-spectrum agents when possible
• Complete full course of therapy
• Antibiotic stewardship programs in hospitals
• Infection control - hand hygiene, barrier precautions
• Avoid antibiotics in agriculture/animal husbandry
• Combination therapy to prevent resistance emergence
• Development of new antibiotics and alternative therapies

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Q3. Penicillins

Mechanism of Action:

Classification:

Antibacterial Spectrum:

• Gram-positive: Streptococcus, Enterococcus, Listeria
• Gram-negative (broad spectrum): E. coli, Haemophilus, Klebsiella (with inhibitors)
• Spirochetes: Treponema pallidum
• Anaerobes: Clostridium, Bacteroides (with inhibitors)

Therapeutic Use:

• Streptococcal pharyngitis, pneumococcal pneumonia, syphilis (Pen G)
• Skin/soft tissue infections (ampicillin/amoxicillin)
• Hospital-acquired infections, intra-abdominal infections (pip-tazo)
• MSSA infections (nafcillin/oxacillin)

Resistance:

• Beta-lactamase production (most common) - cleaves beta-lactam ring
• Altered PBPs - e.g., PBP2a in MRSA (mecA gene)
• Reduced permeability via porin changes
• Efflux pumps

Adverse Effects:

• Hypersensitivity (most important) - urticaria, anaphylaxis (0.05%), rash
• GI - nausea, diarrhea; pseudomembranous colitis (ampicillin)
• CNS - seizures at very high doses
• Interstitial nephritis (methicillin - now withdrawn)
• Hematologic - Coombs-positive hemolytic anemia, neutropenia (with high doses)
• Ampicillin causes maculopapular rash in patients with EBV infection

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Q4. Cephalosporins

Mechanism of Action:

Classification (Generations):

Antibacterial Spectrum:

• As generations increase, gram-negative coverage improves; gram-positive coverage relatively decreases
• 3rd/4th generation: CNS penetration; useful for meningitis
• 5th generation: covers MRSA

Therapeutic Use:

• 1st gen: Surgical prophylaxis, skin/soft tissue, UTI
• 2nd gen: Respiratory infections, intra-abdominal (cefoxitin)
• 3rd gen: Meningitis (ceftriaxone), gonorrhea, serious gram-negative infections, typhoid
• 4th gen: Febrile neutropenia, hospital-acquired infections
• 5th gen: MRSA infections, CAP with MRSA risk

Resistance:

• Extended-spectrum beta-lactamases (ESBLs) - destroy 3rd generation cephalosporins
• AmpC beta-lactamases - encoded chromosomally in Enterobacter, Citrobacter
• Modified PBPs
• Efflux pumps, reduced porins

Adverse Effects:

• Hypersensitivity - ~1-2% cross-reactivity with penicillin allergy
• GI - nausea, diarrhea
• Bleeding - some 3rd gen (cefoperazone) inhibit Vitamin K-dependent clotting factors
• Disulfiram-like reaction (with alcohol - MTT side chain drugs)
• Ceftriaxone - biliary sludging, pseudocholelithiasis in children

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Q5. Carbapenems

Mechanism of Action:

Classification:

Antibacterial Spectrum:

• Gram-positives (including Enterococcus - imipenem)
• Gram-negatives including Pseudomonas (except ertapenem)
• Anaerobes (Bacteroides fragilis)
• ESBL-producing organisms
• NOT active against MRSA, VRE, Stenotrophomonas

Therapeutic Use:

• Polymicrobial infections, intra-abdominal sepsis
• Hospital-acquired pneumonia, ventilator-associated pneumonia
• Febrile neutropenia
• Infections due to ESBL-producing organisms
• Meningitis (meropenem preferred - less seizurogenic)
• Last-resort therapy for multi-drug resistant organisms

Resistance:

• Carbapenemases - KPC (Klebsiella pneumoniae carbapenemase), NDM-1 (New Delhi Metallo-beta-lactamase), OXA-type
• Loss of porins (OmpK35/36 in Klebsiella) combined with ESBL production
• Efflux pumps (in Pseudomonas)

Adverse Effects:

• CNS: Seizures (imipenem more than meropenem - lower seizure threshold)
• GI: Nausea, vomiting, diarrhea
• Hypersensitivity: Cross-reactivity with penicillins (~1%)
• C. difficile colitis - disrupts normal flora
• Elevated liver transaminases (transient)

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Q6. Tetracyclines

Mechanism of Action:

Classification:

Antibacterial Spectrum:

• Gram-positives and gram-negatives (broad spectrum)
• Atypicals: Chlamydia, Mycoplasma, Rickettsia, Coxiella, Brucella
• Spirochetes (Lyme disease - Borrelia)
• Some protozoa (malaria prophylaxis - doxycycline)
• Acne (Propionibacterium acnes)

Therapeutic Use:

• Chlamydia (drug of choice), Mycoplasma pneumonia
• Rickettsia (Rocky Mountain spotted fever)
• Lyme disease (early stages)
• Acne vulgaris (long-term, low-dose doxycycline)
• Cholera, Brucellosis, Q fever
• SIADH (demeclocycline - causes nephrogenic DI)
• Malaria prophylaxis (doxycycline)

Resistance:

• Efflux pumps (tet genes) - most common mechanism
• Ribosomal protection proteins - protect 30S subunit from drug
• Tigecycline is less affected because it is a poor substrate for efflux pumps

Adverse Effects:

• Tooth discoloration and enamel hypoplasia (children < 8 years, pregnancy) - CONTRAINDICATED
• Photosensitivity (especially demeclocycline)
• GI: Nausea, vomiting, esophageal ulceration (take with water upright)
• Hepatotoxicity (high doses in pregnancy)
• Renal: Fanconi syndrome (outdated/degraded tetracycline)
• Vestibular effects - dizziness, vertigo (minocycline)
• Chelate divalent cations (Ca2+, Mg2+, Fe2+) - impaired absorption with dairy/antacids

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Q7. Aminoglycosides

Mechanism of Action:

• Bind 30S ribosomal subunit (specifically 16S rRNA)
• Cause misreading of mRNA - incorporation of wrong amino acids
• Also cause membrane disruption - cell death
• Concentration-dependent bactericidal - killing depends on peak concentration (Cmax/MIC ratio)
• Require oxygen for uptake - therefore INACTIVE against anaerobes

Classification:

Antibacterial Spectrum:

• Gram-negatives (primary): Pseudomonas, E. coli, Klebsiella, Enterobacter
• Synergy with beta-lactams against gram-positives (Enterococcus, Streptococcus)
• Mycobacteria (streptomycin, amikacin)
• NOT anaerobes

Therapeutic Use:

• Serious gram-negative infections (bacteremia, sepsis, UTI)
• Pseudomonal infections (esp. tobramycin)
• Combination therapy for Enterococcal endocarditis (synergy)
• TB (streptomycin, amikacin - second-line)
• Topical (neomycin) - skin infections, ophthalmology
• Inhaled tobramycin - cystic fibrosis

Resistance:

• Enzymatic modification (most common) - acetyltransferases, phosphotransferases, adenylyltransferases modify drug
• Ribosomal mutation - altered 30S subunit
• Reduced uptake - loss of membrane transport
• Amikacin is least susceptible to enzymatic inactivation

Adverse Effects:

• Nephrotoxicity (dose-dependent, reversible) - proximal tubular damage; monitor creatinine
• Ototoxicity (cochlear + vestibular, often irreversible) - deafness, tinnitus, vertigo
• Neuromuscular blockade - can worsen myasthenia gravis; use Ca2+ as antidote
• Risk factors: prolonged use, high doses, renal failure, concurrent nephrotoxic drugs
• Therapeutic drug monitoring is essential (peak and trough levels)

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Q8. Macrolides

Mechanism of Action:

Classification:

Antibacterial Spectrum:

• Gram-positives: Streptococcus, Staphylococcus (not MRSA)
• Atypicals: Mycoplasma, Chlamydia, Legionella, Bordetella, Campylobacter
• Mycobacteria (clarithromycin - MAC prophylaxis/treatment in HIV)
• Spirochetes (early Lyme disease)
• H. pylori (clarithromycin component of triple therapy)

Therapeutic Use:

• Community-acquired pneumonia (CAP) - drug of choice for atypical coverage
• Streptococcal infections in penicillin-allergic patients
• Pertussis (whooping cough)
• STIs: Chlamydia, Ureaplasma (azithromycin 1g single dose)
• MAC prophylaxis/treatment in HIV (clarithromycin/azithromycin)
• H. pylori eradication (clarithromycin + amoxicillin + PPI)
• GI prokinetic (erythromycin)

Resistance:

• Methylation of 23S rRNA (erm genes) - most common; also confers cross-resistance to lincosamides and streptogramin B (MLS resistance)
• Efflux pumps (mef genes)
• Ribosomal mutations

Adverse Effects:

• GI (most common): Nausea, vomiting, diarrhea, abdominal cramps (especially erythromycin)
• QT prolongation - risk of arrhythmias (torsades de pointes); avoid with other QT-prolonging drugs
• Hepatotoxicity - cholestatic jaundice (erythromycin estolate)
• Drug interactions - potent CYP3A4 inhibitors (erythromycin, clarithromycin)
• Ototoxicity - rare, high doses of erythromycin
• Telithromycin - hepatotoxicity, visual disturbances

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Q9. Quinolones (Fluoroquinolones)

Mechanism of Action:

• DNA gyrase: primary target in gram-negatives
• Topoisomerase IV: primary target in gram-positives

Classification:

Antibacterial Spectrum:

• Gram-negatives (excellent): Enterobacteriaceae, Pseudomonas (ciprofloxacin)
• Gram-positives (3rd/4th gen): Pneumococcus, Streptococcus
• Atypicals: Mycoplasma, Chlamydia, Legionella
• Mycobacteria (moxifloxacin - 2nd line TB)
• Anaerobes (moxifloxacin)

Therapeutic Use:

• UTIs and complicated UTIs (ciprofloxacin, norfloxacin)
• Respiratory infections/CAP (levofloxacin, moxifloxacin - "respiratory quinolones")
• Typhoid fever, traveler's diarrhea
• Anthrax (ciprofloxacin - drug of choice)
• STIs: Gonorrhea (but resistance increasing)
• TB - 2nd line (moxifloxacin, levofloxacin)
• Bone and joint infections

Resistance:

• Mutations in DNA gyrase (gyrA) and topoisomerase IV (parC) genes
• Efflux pumps - most common in Pseudomonas
• Plasmid-mediated resistance (qnr genes) - protect topoisomerases
• Resistance can develop rapidly during therapy (step-wise mutations)

Adverse Effects:

• Tendinopathy and tendon rupture (Achilles tendon) - especially in elderly + corticosteroids; BLACK BOX WARNING
• CNS: Headache, dizziness, insomnia; rarely seizures (lower seizure threshold)
• QT prolongation - risk of arrhythmias
• Photosensitivity (especially sparfloxacin)
• GI: Nausea, diarrhea
• Cartilage damage - CONTRAINDICATED in children < 18 years and pregnancy
• Peripheral neuropathy - may be irreversible
• Drug interactions: chelation with antacids, Mg2+, Fe2+

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Q10. Sulfonamides

Mechanism of Action:

Classification:

Antibacterial Spectrum:

• Gram-positives and gram-negatives (broad spectrum)
• Nocardia, Pneumocystis jirovecii (PCP)
• Toxoplasma (with pyrimethamine)
• Malaria (sulfadoxine-pyrimethamine)

Therapeutic Use:

• TMP-SMX: UTIs (first-line), PCP (treatment and prophylaxis in HIV)
• PCP treatment (high-dose TMP-SMX = drug of choice)
• Toxoplasmosis prophylaxis in HIV (TMP-SMX)
• Nocardiosis
• Traveler's diarrhea
• Sulfadoxine-pyrimethamine: Malaria (Fansidar)
• Silver sulfadiazine: Burn wound infections
• Sulfasalazine: Ulcerative colitis, Crohn's, rheumatoid arthritis

Resistance:

• Mutation in dihydropteroate synthase (reduced drug binding)
• Overproduction of PABA by bacteria
• Plasmid-mediated resistance acquisition

Adverse Effects:

• Hypersensitivity: Rash, Stevens-Johnson syndrome (severe - life-threatening)
• Hematologic: Hemolytic anemia (in G6PD deficiency), agranulocytosis, thrombocytopenia
• Renal: Crystalluria and nephrotoxicity (maintain good hydration)
• Kernicterus - displace bilirubin from albumin - CONTRAINDICATED in neonates/late pregnancy
• Drug interactions: Displace warfarin, methotrexate from albumin
• Photosensitivity

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Q11. Antimycobacterial Drugs (Treatment of Tuberculosis)

First-Line Drugs (RIPE):

Standard Regimen:

• Intensive phase (2 months): RIPE (all four drugs)
• Continuation phase (4 months): RI (Rifampicin + Isoniazid)
• Total: 6 months for drug-sensitive TB

Second-Line Drugs (for MDR-TB and XDR-TB):

• Fluoroquinolones (Moxifloxacin, Levofloxacin)
• Injectable agents (Amikacin, Streptomycin, Capreomycin)
• Newer drugs: Bedaquiline (inhibits ATP synthase), Linezolid, Delamanid

Resistance:

• MDR-TB: Resistant to at least Rifampicin + Isoniazid
• XDR-TB: MDR-TB + resistant to fluoroquinolones and injectable agents
• Mechanisms: Mutations in rpoB (rifampicin), katG/inhA (isoniazid), pncA (pyrazinamide), embB (ethambutol)
• Poor adherence is the most common cause of acquired resistance

Adverse Effects:

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Q12. Antifungal Drugs

Classification:

Antifungal Spectrum & Therapeutic Use:

Resistance:

• Azoles: Mutations in CYP51 (ERG11), efflux pump upregulation (CDR genes in Candida)
• Echinocandins: Mutations in FKS1/FKS2 (glucan synthase genes)
• Amphotericin B: Reduced ergosterol content in membrane (rare resistance)

Adverse Effects:

• Amphotericin B: Infusion reactions ("shake and bake" - fever, rigors, chills); nephrotoxicity (dose-limiting); hypokalemia, hypomagnesemia; anemia
• Azoles: Hepatotoxicity; CYP450 inhibition (major drug interactions); QT prolongation (voriconazole); visual disturbances (voriconazole); teratogenic (CONTRAINDICATED in pregnancy)
• Echinocandins: Well-tolerated; hepatotoxicity (mild); histamine release (caspofungin)
• Flucytosine: Bone marrow suppression; GI toxicity; monitor blood levels

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Q13. Antiviral Drugs for Herpes Virus Infections

Classification & Mechanism of Action:

Therapeutic Use:

• HSV-1/HSV-2 (genital herpes, cold sores): Acyclovir, Valacyclovir, Famciclovir
• HSV encephalitis: IV Acyclovir (drug of choice)
• Herpes Zoster (shingles/VZV): Valacyclovir, Famciclovir (better for VZV)
• Neonatal herpes: IV Acyclovir
• CMV retinitis/colitis (in HIV): Ganciclovir/Valganciclovir (first-line)
• CMV resistant to ganciclovir: Foscarnet, Cidofovir
• Acyclovir-resistant HSV: Foscarnet

Adverse Effects:

• Acyclovir: Generally well tolerated; nephrotoxicity (crystalluria - maintain hydration); encephalopathy (high IV doses); phlebitis
• Ganciclovir: Myelosuppression (neutropenia, thrombocytopenia - dose-limiting); teratogenic/carcinogenic; avoid with zidovudine (additive myelosuppression)
• Foscarnet: Nephrotoxicity (major); hypocalcemia (chelates Ca2+) - causes seizures, arrhythmias; electrolyte imbalances
• Cidofovir: Severe nephrotoxicity (give with probenecid and IV saline for protection)

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Q14. Antiviral Drugs for HIV (Antiretroviral Therapy - ART)

Mechanism of Action & Classification:

Current Standard Regimen:

Therapeutic Use:

• Treatment of HIV infection (reduce viral load to undetectable, preserve CD4 count)
• Prevention of opportunistic infections
• PrEP (Pre-Exposure Prophylaxis): Tenofovir/Emtricitabine (Truvada)
• PEP (Post-Exposure Prophylaxis): 3-drug ART within 72 hours
• Prevention of mother-to-child transmission (PMTCT)
• Goal: Undetectable viral load = untransmittable (U=U)

Resistance:

• High mutation rate of reverse transcriptase (no proofreading)
• NRTI: M184V mutation (lamivudine/emtricitabine); K65R (tenofovir)
• NNRTI: K103N (efavirenz/nevirapine) - single mutation causes high-level resistance
• PI: Multiple mutations needed; boosting with ritonavir compensates
• Prevention: Combination therapy (HAART) - multiple simultaneous mutations required

Adverse Effects:

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Q15. Antiseptics

Definition:

Classification & Mechanisms of Action:

Therapeutic & Practical Use:

• Povidone-iodine: Wound antisepsis, surgical scrub, mucosal disinfection, vaginal infections
• Chlorhexidine: Surgical hand scrub, wound care, oral rinse (gingivitis), catheter site care, neonatal eye care; has residual activity (adsorbs to skin)
• Ethanol 70%: Hand sanitization, skin preparation before injection
• Hydrogen peroxide: Wound cleaning (mechanical debridement via oxygen release), ear wax
• Silver sulfadiazine: Burns (antibacterial + antifungal coverage)
• Benzalkonium chloride: Eye drops, wound care, skin antisepsis
• Potassium permanganate: Fungal skin infections, eczema (wet dressings)

Resistance:

• Intrinsic resistance in some organisms (e.g., spores, mycobacteria resist alcohols)
• Biofilm formation - significant protective barrier
• Efflux pumps - e.g., qac genes (quaternary ammonium compound resistance) in Staphylococcus
• Cross-resistance between antiseptics and antibiotics (e.g., qac gene expression associated with MRSA efflux pumps)
• Generally, resistance is less problematic than with antibiotics

Adverse Effects:

• Iodine: Skin irritation; iodine allergy; systemic absorption causing thyroid dysfunction (prolonged use)
• Chlorhexidine: Rare hypersensitivity (anaphylaxis possible); ototoxic (do NOT use in the ear canal); staining of teeth and tongue (oral use)
• Alcohols: Skin drying, dermatitis; flammable; ineffective against spores
• Hydrogen peroxide: Tissue damage at high concentrations; gas embolism (in deep wounds)
• Silver compounds: Argyria (blue-grey skin discoloration with prolonged use)
• Phenols: Skin irritation, necrosis; systemic absorption causes CNS toxicity
• Quaternary ammonium compounds: Skin irritation; anaphylaxis (rare)

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Key Exam Tips:

• Beta-lactams (penicillins, cephalosporins, carbapenems) all inhibit cell wall synthesis via PBPs
• Aminoglycosides and tetracyclines both target 30S; macrolides target 50S
• Fluoroquinolones = concentration-dependent; beta-lactams = time-dependent
• TB treatment: RIPE x 2 months + RI x 4 months = 6 months total
• HIV standard regimen: 2 NRTIs + 1 INSTI
• Foscarnet does NOT need viral kinase activation (used for acyclovir/ganciclovir-resistant infections)

ANTIMICROBIAL & ANTIVIRAL DRUGS

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1. Classification of Antibiotics by Mechanism of Action

• Penicillins
• Cephalosporins
• Carbapenems
• Vancomycin

• Aminoglycosides (30S)
• Tetracyclines (30S)
• Macrolides (50S)
• Chloramphenicol (50S)

• Quinolones (DNA replication)
• Rifampicin (RNA synthesis)
• Metronidazole

• Sulfonamides
• Trimethoprim

• Polymyxins
• Daptomycin

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2. Mechanisms of Bacterial Resistance to Antibiotics

• Enzymatic destruction of drug (β-lactamases).
• Alteration of target site.
• Decreased permeability of bacterial cell wall.
• Active efflux pumps.
• Bypass of metabolic pathway.

• Rational antibiotic use.
• Culture and sensitivity testing.
• Complete treatment course.
• Avoid unnecessary prescriptions.
• Combination therapy when indicated.
• Hospital infection-control measures.
• Surveillance of resistant strains.

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3. Penicillins

• Mainly Gram-positive bacteria.
• Some Gram-negative organisms.

• Natural: Penicillin G, Penicillin V.
• Penicillinase-resistant: Oxacillin, Cloxacillin.
• Aminopenicillins: Ampicillin, Amoxicillin.
• Antipseudomonal: Piperacillin, Ticarcillin.

• Streptococcal infections.
• Syphilis.
• Meningitis.
• Respiratory and urinary tract infections.

• β-lactamase production.
• Altered PBPs.
• Reduced permeability.

• Hypersensitivity reactions.
• Rash.
• Diarrhea.
• Anaphylaxis.

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4. Cephalosporins

• Broad-spectrum activity.
• Later generations have greater Gram-negative coverage.

• 1st: Cefazolin, Cephalexin.
• 2nd: Cefuroxime.
• 3rd: Ceftriaxone, Ceftazidime.
• 4th: Cefepime.
• 5th: Ceftaroline.

• Pneumonia.
• Meningitis.
• Sepsis.
• Urinary tract infections.

• β-lactamases.
• Altered PBPs.

• Allergy.
• Diarrhea.
• Superinfection.
• Rare nephrotoxicity.

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5. Carbapenems

• Imipenem.
• Meropenem.
• Ertapenem.
• Doripenem.

• Very broad spectrum.
• Effective against Gram-positive, Gram-negative and anaerobic bacteria.

• Severe hospital-acquired infections.
• Sepsis.
• Complicated intra-abdominal infections.

• Carbapenemase enzymes.
• Efflux pumps.
• Porin mutations.

• Nausea.
• Diarrhea.
• Rash.
• Seizures (especially imipenem).

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6. Tetracyclines

• Tetracycline.
• Doxycycline.
• Minocycline.

• Broad spectrum.
• Effective against atypical organisms.

• Acne.
• Cholera.
• Rickettsial infections.
• Chlamydia.
• Lyme disease.

• Efflux pumps.
• Ribosomal protection proteins.

• Gastrointestinal irritation.
• Photosensitivity.
• Teeth discoloration.
• Hepatotoxicity.

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7. Aminoglycosides

• Gentamicin.
• Amikacin.
• Tobramycin.
• Streptomycin.

• Severe systemic infections.
• Tuberculosis (streptomycin).
• Sepsis.

• Drug-inactivating enzymes.
• Ribosomal mutations.

• Nephrotoxicity.
• Ototoxicity.
• Neuromuscular blockade.

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8. Macrolides

• Erythromycin.
• Clarithromycin.
• Azithromycin.

• Gram-positive cocci.
• Atypical organisms.

• Respiratory tract infections.
• Mycoplasma pneumonia.
• Chlamydial infections.

• Ribosomal modification.
• Efflux pumps.

• Nausea.
• Diarrhea.
• QT prolongation.
• Cholestatic hepatitis.

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9. Quinolones

• Ciprofloxacin.
• Levofloxacin.
• Moxifloxacin.
• Ofloxacin.

• Broad-spectrum activity.
• Excellent Gram-negative coverage.

• UTIs.
• Gastrointestinal infections.
• Respiratory infections.

• DNA gyrase mutations.
• Efflux pumps.

• Tendon rupture.
• QT prolongation.
• Gastrointestinal upset.
• CNS effects.

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10. Sulfonamides

• Sulfamethoxazole.
• Sulfadiazine.
• Sulfisoxazole.

• Urinary tract infections.
• Pneumocystis jirovecii pneumonia.
• Toxoplasmosis.

• Altered enzyme.
• Increased PABA production.

• Hypersensitivity.
• Stevens-Johnson syndrome.
• Hemolysis in G6PD deficiency.
• Crystalluria.

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11. Antimycobacterial Drugs (Tuberculosis)

• Isoniazid (INH)
• Rifampicin
• Pyrazinamide
• Ethambutol
• Streptomycin

• INH: inhibits mycolic acid synthesis.
• Rifampicin: inhibits RNA polymerase.
• Pyrazinamide: disrupts membrane function.
• Ethambutol: inhibits cell wall synthesis.
• Streptomycin: inhibits protein synthesis.

• INH: peripheral neuropathy, hepatitis.
• Rifampicin: hepatotoxicity, orange secretions.
• Ethambutol: optic neuritis.
• Pyrazinamide: hyperuricemia.
• Streptomycin: ototoxicity.

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12. Antifungal Drugs

• Polyenes: Amphotericin B, Nystatin.
• Azoles: Fluconazole, Ketoconazole.
• Echinocandins: Caspofungin.
• Antimetabolite: Flucytosine.
• Allylamines: Terbinafine.

• Candidiasis.
• Aspergillosis.
• Cryptococcosis.
• Dermatophyte infections.

• Altered ergosterol synthesis.
• Efflux pumps.

• Amphotericin B: nephrotoxicity.
• Azoles: hepatotoxicity.
• Flucytosine: bone marrow suppression.

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13. Antiviral Drugs for Herpes Virus Infection

• Acyclovir, Valacyclovir, Famciclovir:
  • Inhibit viral DNA polymerase.
• Ganciclovir:
  • Active against CMV.

• Herpes simplex virus (HSV).
• Varicella-zoster virus (VZV).
• Cytomegalovirus (CMV).

• Nausea.
• Headache.
• Nephrotoxicity (acyclovir).
• Bone marrow suppression (ganciclovir).

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14. Antiviral Drugs for HIV

• Inhibit reverse transcriptase.

• Directly inhibit reverse transcriptase.

• Inhibit viral protease.

• Prevent integration of viral DNA.

• Hepatotoxicity.
• Lipodystrophy.
• Metabolic abnormalities.
• Gastrointestinal disturbances.

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15. Antiseptics

• Alcohols: Ethanol, Isopropanol.
• Halogens: Iodine, Povidone-iodine.
• Oxidizing agents: Hydrogen peroxide.
• Biguanides: Chlorhexidine.
• Phenolic compounds.

• Protein denaturation.
• Oxidation.
• Cell membrane disruption.
• Enzyme inhibition.

• Hand disinfection.
• Surgical skin preparation.
• Wound cleansing.
• Prevention of infection.

• Skin irritation.
• Allergic reactions.
• Chemical burns with improper use.