Antimicrobial Treatments

Antimicrobial Treatments

• Antibiotics are naturally produced by microbes such as Penicillium which produces penicillin, and Streptomyces that produces streptomycin.
• Kirby-Bauer tests utilize antibiotic disks on agar, measuring zones of inhibition
• Minimum Inhibitory Concentration (MIC) determines the lowest concentration of an antibiotic needed to inhibit visible bacterial growth.
• In Kirby-Bauer tests, larger zones indicate more effective antibiotics
• In MIC tests, lower MIC values signify more effective antibiotics
• Narrow-spectrum antibiotics target specific bacteria like Gram-positive only
• Broad-spectrum antibiotics affect a wide range of bacteria including both Gram-positive and Gram-negative types
• Therapeutic Index (TI) is the ratio of toxic dose to effective dose; a higher TI indicates a safer drug.
• Beta-lactams (penicillins, cephalosporins) target the cell wall by inhibiting peptidoglycan synthesis.
• Aminoglycosides, tetracyclines, and macrolides target protein synthesis by binding to ribosomal subunits (30S or 50S).
• Fluoroquinolones and rifampin target DNA/RNA by inhibiting DNA gyrase or RNA polymerase.
• Sulfonamides and trimethoprim target folic acid by inhibiting the folic acid synthesis pathway
• Common fungal drugs: Amphotericin B, fluconazole, clotrimazole
• Common protozoal drugs: Metronidazole (Flagyl), chloroquine
• Common helminth drugs: Mebendazole, ivermectin, praziquantel
• Drug resistance can occur through mutations or horizontal gene transfer.
• Plasmids carry resistance genes and are transferable between bacteria
• Broad-spectrum antibiotics can disrupt normal flora, leading to resistance.
• Emerging antimicrobial approaches include phage therapy, probiotics, bacteriocins, CRISPR, antimicrobial peptides, and host defense boosters.
• Hepatotoxic substances cause liver damage
• Nephrotoxic substances cause kidney damage
• Neurotoxic substances cause nervous system damage
• Superinfection is a secondary infection resulting from disruption of normal flora, such as C. diff.

Infection & Epidemiology

• Zoonotic infections are diseases transmitted from animals to humans, such as rabies and Lyme disease
• Septicemia is an infection in the blood, Bacteremia is bacteria in the blood, Viremia is viruses in the blood
• True pathogens cause disease in a healthy host
• Opportunistic pathogens cause disease in a compromised host
• Exotoxins are secreted proteins like tetanus toxin
• Endotoxins are Lipid A of LPS, released from dead Gram-negative bacteria.
• A reservoir is the habitat where a pathogen lives, such as humans, animals, water, or soil.
• Epidemiology is the study of disease patterns and transmission.
• Infectious dose is the minimum number of microbes needed to cause disease
• Symptomatic infections present with symptoms
• Asymptomatic infections have no symptoms but the individual is still infected.
• Leukopenia is a low white blood cell count
• Sequelae are long-term effects post-infection, like heart damage after rheumatic fever.
• Normal flora are non-harmful microbes that protect against pathogens.

Respiratory Tract Infections

• Respiratory biota includes Streptococcus, Haemophilus, and Neisseria
• Respiratory defenses include mucus, cilia, IgA, and macrophages.
• The upper respiratory tract consists of the nose, sinuses, pharynx, and larynx.
• The lower respiratory tract consists of the trachea, bronchi, and lungs.
• Pharyngitis is caused by Group A Streptococcus
• Pharyngitis symptoms: Sore throat and fever
• Pharyngitis complications: Scarlet fever and rheumatic fever
• Pharyngitis spreads through droplets, is diagnosed via rapid test, and treated with penicillin.
• The common cold is caused by rhinoviruses and coronaviruses.
• Sinusitis is the inflammation of sinuses, often following a cold or allergies.
• Otitis media is caused by Streptococcus pneumoniae and Haemophilus influenzae
• Otitis media travels through the Eustachian tube to infect the middle ear
• Otitis media is be treated with antibiotics, or through observation to see if it resolves on its own
• Influenza is caused by the influenza virus.
• Influenza symptoms include fever, cough, and body aches.
• Influenza is spread via droplets, diagnosed with a rapid test, and treated with antivirals like Tamiflu.
• RSV spreads via droplets and poses a high risk to infants and the elderly
• Streptococcus pneumoniae is Gram-positive and causes pneumonia.
• Mycoplasma pneumoniae lacks a cell wall and causes "walking pneumonia."
• Legionella pneumophila is found in water and causes Legionnaires' disease.
• Hantavirus is transmitted from rodents and was the cause of the Yosemite outbreak.
• SARS-CoV-2 is the virus that causes COVID-19 and spreads via droplets/aerosols.
• Histoplasma capsulatum is a fungus found in bird/bat droppings and prevalent in the Midwest U.S.
• Healthcare-associated pneumonia (VAP) is caused by Pseudomonas and MRSA.
• Bordetella pertussis causes whooping cough and produces toxins that paralyze cilia.
• Tuberculosis (TB) is diagnosed via skin test (PPD), chest X-ray, and sputum analysis.
• Primary TB is the initial infection
• Secondary TB is the reactivated infection that occurs later in life.