Module 12: Infections

Administrative and Course Information

• The attendance code for the current session is 6650.

• Learning objectives for the infection section include:

  • Describing the process of infection.

  • Defining the stages of infection.

  • Explaining the characteristics and stages of bacterial infection.

  • Explaining why antibiotic resistance has emerged.

  • Discussing alterations in pulmonary function (Tuberculosis, acute bronchitis, pneumonia).

  • Discussing digestive function, specifically differentiating between Hepatitis A, B, and C.

  • Describing the clinical course of hepatitis from incubation to recovery.

  • Discussing the structure, function, and disorders of the integumentary system (Skin infections: herpes simplex, zoster, tinea, and candidiasis/yeast infections).

• Prototype Drugs: Students are encouraged to create drug cards for all prototype medications to understand indications, contraindications, and patient education.

Medical Mathematics and Conversions

• Metric Abbreviations: Use acceptable abbreviations for units of measure (e.g., mg for milligram, mL for milliliter, etc.).

• Intake and Output (I&O) Calculation:

  • Example Scenario: A client voided four times during a 12-hour shift with volumes of $350\,\text{mL}$, $275\,\text{mL}$, $450\,\text{mL}$, and $300\,\text{mL}$.

  • Calculation: $\text{Total Output} = 350 + 450 + 300 + 275 = 1,375\,\text{mL}$.

• Height Conversion (Feet to Centimeters):

  • Formula: $\text{Height in inches} = \text{Feet} \times 12$

  • Conversion factor: $1\,\text{inch} = 2.54\,\text{cm}$.

  • Example for a $6\,\text{foot}$ tall patient:

    • $6\,\text{ft} \times 12\,\text{inches/ft} = 72\,\text{inches}$

    • $72\,\text{inches} \times 2.54\,\text{cm/inch} = 182.88\,\text{cm}$.

  • Rounded to the nearest whole number: $183\,\text{cm}$.

Pathophysiology of Infection

• Infection Definition: A process that results when a pathogen invades tissues and begins growing within a host. Pathogens break through the first line of defense (innate immune system) and replicate, causing negative effects on tissues like skin or mucous membranes.

• Key Terms:

  • Pathogenicity: The ability of an organism to produce a disease.

  • Virulence: The capacity of an organism to cause severe disease.

• High-Risk Populations:

  • Immunocompromised: Patients with HIV, cancer (receiving chemotherapy), or those on immunosuppressant/anti-rejection medications for autoimmune diseases or transplants.

  • Young Children: Their immune systems are not yet fully developed.

  • Elderly: Immune systems naturally become more suppressed with age.

  • Chronic Conditions: Individuals with diabetes, heart disease, or respiratory problems.

  • Malnourished: Includes both undernourished individuals and those who are overnourished but consume a diet lacking vital vitamins and minerals.

• Stages of Infection:

  • Encounter: The source (food, water, insects, injury).

  • Transmission: Direct (body-to-body fluids) or indirect (touching contaminated doorknobs).

  • Colonization: The pathogen fights through innate defenses, adheres to receptor sites, and multiplies.

  • Invasion/Penetration: Pathogens enter-through skin or membranes and spread.

  • Dissemination: The infection spreads throughout the entire body.

  • Tissue Damage: Results in inflammation, swelling, scarring, and necrosis.

• Clinical Process of Infection:

  • Incubation Period: Time from exposure to the onset of symptoms (hours to years).

  • Prodromal Stage: Onset of initial, often vague, symptoms as pathogens multiply.

  • Invasion Stage: Spread of the pathogen; symptoms become more systemic and severe.

  • Convalescence: Successful immune response removes the agent, or the infection becomes fatal.

• Crucial Rule: Infectious diseases can be contagious during all stages of the infection process.

Antibiotic Resistance and Misuse

• Antimicrobial Resistance: Occurs when a drug no longer treats or kills a microorganism because the bacteria has evolved or adapted.

• Causes of Resistance:

  • Taking antibiotics for viral infections (e.g., flu, cold, COVID-19).

  • Taking antibiotics incorrectly (skipping doses, not finishing the course).

  • Misuse allows lingering bacteria to "evolve" and become resistant.

• Healthcare-Acquired Infections (HAIs): Infections patients acquire while in the hospital (pneumonia, UTIs, central line infections). Examples include MRSA (Methicillin-resistant Staphylococcus aureus), VRE (Vancomycin-resistant Enterococcus), and VRSA (Vancomycin-resistant Staphylococcus aureus).

• Cross-Resistance: Occurs between antibacterial drugs with similar actions (e.g., if resistant to penicillin, may also be resistant to amoxicillin).

Pharmacology of Antibacterial Agents

General Adverse Reactions

• Allergic Reactions: Range from mild (itching, hives) to severe (anaphylaxis). Pre-medication (e.g., Benadryl) may be used for mild allergies if the benefit outweighs the risk.

• Superinfection: Secondary infection occurring when normal flora are killed (e.g., C. diff, vaginal yeast infections, oral thrush).

• Organ Toxicity: Can affect the liver (hepatotoxicity), kidneys (nephrotoxicity), or ears (ototoxicity/tinnitus).

Penicillins and Cephalosporins

• Amoxicillin (Penicillin):

  • Action: Inhibits bacterial cell wall synthesis (beta-lactam ring).

  • Use: Broad-spectrum; treats various bacterial infections.

  • Side Effects: Hypersensitivity, tongue discoloration (benign), stomatitis, and glossitis (swelling of tongue/throat).

  • Consideration: Lowers efficacy of oral contraceptives.

• Ceftriaxone (Cephalosporin):

  • Action: Inhibits cell wall synthesis; bactericidal.

  • Side Effects: Anaphylaxis, GI distress, increased bleeding, elevated hepatic enzymes, nephrotoxicity.

  • Nursing Priority: Monitor for superinfection signs.

Other Antibiotic Prototypes

• Metronidazole:

  • Use: Bacterial vaginosis, Trichomonas (STD), anaerobic infections.

  • Side Effects: Metallic taste, GI distress, dizziness.

  • Contraindications: First trimester of pregnancy, breastfeeding, neoplastic disease.

  • Adverse effects: Seizures; requires monitoring of LFTs and RFTs (Liver/Renal Function Tests).

• Azithromycin (Macrolide):

  • Use: Bacterial conjunctivitis, whooping cough, ear infections, STIs, pneumonia.

  • Side Effects: Photosensitivity, tinnitus, tongue discoloration, blurred vision.

  • Adverse effects: C. diff, hearing loss, angioedema, Steven-Johnson syndrome.

  • Nursing: Administer antacids $2\,\text{hours}$ before or after dose.

• Doxycycline (Tetracycline):

  • Use: Acne, STIs (Chlamydia), pneumonia, plague.

  • Contraindications: Do not give to children < 8\,\text{years} old (causes permanent teeth discoloration) or pregnant women (teratogenic effects).

  • Side Effects: Photosensitivity, GI distress.

• Gentamicin Sulfate (Aminoglycoside):

  • Use: Serious infections, endocarditis, meningitis.

  • Toxicity: Highly nephrotoxic and ototoxic (monitor hearing/renal function).

  • Interactions: Penicillins decrease effectiveness; increases action of oral anticoagulants (monitor INR, target $2-3$ for Warfarin).

  • Monitoring: Peak and Trough levels.

• Ciprofloxacin (Fluoroquinolone):

  • Use: Anthrax, UTIs, respiratory infections.

  • Black Box Warning: Risk of tendonitis and tendon rupture; peripheral neuropathy.

  • Education: Discontinue if tendon pain occurs; avoid strenuous exercise.

• Trimethoprim-Sulfamethoxazole (Sulfonamide):

  • Use: UTIs, otitis media.

  • Side Effects: Crystalluria.

  • Education: Drink at least $2-3\,\text{L}$ of water daily; avoid antacids; contraindicated if allergic to sulfa or eggs.

Viral and Fungal Infections

• Hepatitis:

  • Hep A: Fecal-oral route; common in daycare settings; prevented by vaccine.

  • Hep B: Blood-borne/body fluids; mother-to-baby transmission; prevented by vaccine.

  • Hep C: Primarily via IV drug use/needle sharing; chronic cases last > 6\,\text{months}.

  • Monitoring: ALT and AST levels for liver damage.

• Herpes Viruses:

  • HSV-1: Cold sores (saliva transmission); can cause genital herpes via oral sex.

  • HSV-2: Genital herpes (skin-to-skin contact).

  • Herpes Zoster (Shingles): Reactivation of varicella virus in the dorsal root ganglia; painful; requires antivirals (Acyclovir).

• Skin and Fungal Infections:

  • Tinea Capitis: Fungal infection of the scalp ("ringworm"); requires systemic oral treatment, not just topicals.

  • Tinea Corporis: Ringworm on the body; treated with topicals.

  • Candidiasis (Yeast): Oral thrush (white plaques) or vaginal infections; treated with Nystatin (swish and swallow) or Fluconazole.

Tuberculosis and Parasites

• Tuberculosis (TB):

  • Caused by Mycobacterium tuberculosis.

  • Latent Phase: Asymptomatic; positive PPD or chest X-ray.

  • Active Phase: Coughing blood, night sweats, weight loss.

  • PPD Reading: Inspect in $48-72\,\text{hours}$. Positive if $\ge 15\,\text{mm}$ for low risk or $\ge 10\,\text{mm}$ for high risk.

  • Treatment: Combination therapy (Isoniazid, Rifampin) for $3-9\,\text{months}$.

• Malaria:

  • Transmitted by mosquitoes; affects red blood cells.

  • Symptoms: Fever, chills, sweating.

  • Nursing: Monitor for vision changes (retinal involvement).

• Helminths:

  • Parasitic worms (roundworms, tapeworms) found in soil and contaminated food.

  • Treatment: Ivermectin ($1-3\,\text{days}$).

Questions & Discussion

• Top Hat: Favorite thing about UF? Students mentioned the summer break, friends, meeting new people, and school being paid for. The instructor mentioned Snoop Dogg and Kanye West quotes.

• Top Hat: Ceftriaxone Priority? The highest priority is monitoring for superinfection.

• Question: Culture vs. Sensitivity? Always collect the culture before starting antibiotics so results are accurate, but do not wait for the results to begin therapy.

• Top Hat: Gentamicin Peak? If given at 18:00 ($6\text{:00 PM}$), the peak should be drawn at 19:00 ($7\text{:00 PM}$), whereas the trough is drawn right before the next dose (e.g., 05:00 if dosing is Q12).