Unit 4 Patho 2

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Questions and Answers

What does virulence refer to in the context of infectious organisms?

The ability of an organism to replicate in the host

The capacity to produce a disease (correct)

How infectious an organism is

The mechanism of infection transmission

Which of the following characteristics is true for Gram-positive bacteria?

They commonly appear pink under a microscope

They have a thin cell wall that does not retain stain

They are usually aerobic organisms

They are effectively killed by penicillin (correct)

Which of the following is a feature of bactericidal drugs?

They promote the development of drug resistance

They kill bacteria outright (correct)

They stop bacteria from replicating

They must be used with another drug to be effective

During which stage of infection are recognizable symptoms first observed?

Prodromal stage Signup and view all the answers

What major risk is associated with the unwarranted use of antibiotics?

Promotion of drug-resistant bacterial strains Signup and view all the answers

Which of the following statements about Chlamydia Trachomatis is correct?

It is the most common STI Signup and view all the answers

What defines the incubation period during an infection?

A time without noticeable symptoms in the host Signup and view all the answers

In what form do Bacilli bacteria exist?

Rod-shaped Signup and view all the answers

What is the primary mechanism by which isoniazid treats tuberculosis?

Inhibits mycolic acid synthesis Signup and view all the answers

Which of the following is NOT a common complication associated with isoniazid?

Renal failure Signup and view all the answers

What is the preferred drug for treating systemic fungal infections?

Amphotericin B Signup and view all the answers

How does Amphotericin B exert its antifungal effect?

Disrupts fungal cell membrane integrity Signup and view all the answers

Which of the following statements about superficial fungal infections is false?

They always require systemic antifungal therapy. Signup and view all the answers

What side effect is commonly associated with the use of Amphotericin B?

Nephrotoxicity Signup and view all the answers

What is the primary risk factor for reactivation of latent tuberculosis?

Severe immune suppression Signup and view all the answers

Chloroquine is effective against which stage of malaria?

Erythrocytic stage Signup and view all the answers

What should be done when a patient presents with a severe infection before culture results are available?

Start broad spectrum antibiotics until lab results are available. Signup and view all the answers

What lifelong precaution should a patient receiving tetracyclines be made aware of?

Avoid the sun due to severe photosensitivity. Signup and view all the answers

What is a common adverse effect associated with the use of aminoglycosides?

Permanent ototoxicity and nephrotoxicity. Signup and view all the answers

Which of the following antibiotics is primarily effective against gram-positive bacteria?

Vancomycin Signup and view all the answers

How should ciprofloxacin be administered to minimize gastrointestinal side effects?

With food to diminish adverse GI effects. Signup and view all the answers

What is an important nursing consideration when administering vancomycin?

Monitor for red man syndrome when infused quickly. Signup and view all the answers

Which statement about cephalosporins is true?

They have a beta-lactam ring structure. Signup and view all the answers

What can occur when tetracyclines are taken with milk products?

They can inhibit the absorption of the medication. Signup and view all the answers

Trimethoprim-sulfamethoxazole is contraindicated in patients with what condition?

Renal impairment. Signup and view all the answers

In which case is broad-spectrum antibiotic therapy first recommended?

In severe infections until specific pathogens are identified. Signup and view all the answers

What dietary restriction should a patient taking erythromycin follow?

Avoid consuming alcohol. Signup and view all the answers

How should nurses manage the potential for nephrotoxicity when administering aminoglycosides?

Monitor renal function closely and adjust dosing as needed. Signup and view all the answers

What is a significant nursing intervention when giving fluoroquinolones?

Notify the doctor if leg pain occurs. Signup and view all the answers

What is the primary reason that Gram-positive bacteria are susceptible to penicillin?

They have a thick cell wall that retains the stain. Signup and view all the answers

Which stage of infection is characterized by the maximum impact of the infectious process?

Acute stage Signup and view all the answers

Which type of bacteria is likely responsible for causing traveler’s diarrhea due to its ability to produce toxins?

E. coli Signup and view all the answers

What does acquired resistance in bacteria primarily result from?

Widespread and unwarranted use of antibiotics Signup and view all the answers

What is the main function of bacteriostatic drugs?

They inhibit the replication of bacteria. Signup and view all the answers

Which characteristic differentiates aerobic bacteria from anaerobic bacteria?

Aerobic bacteria require oxygen for growth. Signup and view all the answers

Which of the following represents a potential complication of antibiotic therapy?

Development of drug-resistant strains Signup and view all the answers

What does the term 'selective toxicity' refer to in the context of anti-infective drugs?

Disrupting bacterial functions without harming human cells Signup and view all the answers

What is the primary reason for the extended treatment duration of tuberculosis lasting 6-12 months?

To counteract the development of drug-resistant strains Signup and view all the answers

Why is isoniazid considered a first-line treatment for tuberculosis?

It effectively inhibits mycolic acid synthesis in bacterial cell walls. Signup and view all the answers

What condition may be exacerbated by the use of isoniazid?

Memory loss and various psychoses Signup and view all the answers

Which pharmacological class does Amphotericin B belong to?

Polyene antifungals Signup and view all the answers

What is a significant adverse effect of Amphotericin B that healthcare providers need to monitor?

Renal impairment and nephrotoxicity Signup and view all the answers

In cases of serious fungal infections, why is it important to use premedication when administering Amphotericin B?

To prevent hypotension and CV collapse during infusion Signup and view all the answers

What mechanism allows Fluconazole to prevent infections from reaching the CNS?

It inhibits the synthesis of ergosterol in fungal cell membranes. Signup and view all the answers

Which statement about protozoan infections, specifically malaria, is accurate?

The disease progresses from the mosquito to the liver before infecting RBCs. Signup and view all the answers

What is the primary characteristic of penicillins regarding their activity against bacteria?

They disrupt the cell wall of bacteria. Signup and view all the answers

What specific drug class does cefazolin belong to?

First-generation cephalosporin Signup and view all the answers

Which complication is most commonly associated with the use of tetracyclines?

Permanent tooth discoloration Signup and view all the answers

Which side effect is specifically noted for aminoglycosides?

Nephrotoxicity Signup and view all the answers

What effect does alcohol have when consumed with cephalosporins?

Causes disulfiram-like reaction Signup and view all the answers

What is the main use of trimethoprim-sulfamethoxazole?

Management of urinary tract infections Signup and view all the answers

What is a common nursing consideration for patients taking fluoroquinolones?

Observe for signs of tendon pain and swelling. Signup and view all the answers

In which situation is it most appropriate to initiate broad-spectrum antibiotic therapy?

Before identifying the specific pathogen in severe infections. Signup and view all the answers

What should a nurse monitor for when administering vancomycin?

Red man syndrome Signup and view all the answers

What is a crucial instruction for a patient taking macrolides?

Avoid taking with grapefruit juice. Signup and view all the answers

For which of the following infections is gentamicin primarily indicated?

Serious systemic infections caused by aerobic gram-negative organisms Signup and view all the answers

Which of the following complications is associated with sulfonamides?

Crystalluria Signup and view all the answers

What safety measure should be taken for patients using tetracyclines?

Avoid all dairy products. Signup and view all the answers

Study Notes

Infection

Pathogens must bypass the body's defenses to infect an individual.
Pathogenicity: How infectious an organism is.
Virulence: How well an organism can produce a disease.
Some bacteria produce toxins that cause illness, for example, E.Coli.
Gram-positive bacteria: Stain purple, have a thick cell wall and are susceptible to penicillin. Examples include Staphylococci, Streptococci, and Enterococci.
Gram-negative bacteria: Stain pink, have a thin cell wall, and are less susceptible to penicillin. Examples include Bacteroides, E.Coli, Klebsiella, Pseudomonas, and Salmonella.
Cell shape: Rod-shaped bacteria are called bacilli, sphere-shaped bacteria are called cocci, and spiral-shaped bacteria are called spirilla.
Aerobic bacteria: Require oxygen to survive.
Anaerobic bacteria: Do not require oxygen to survive.
Chlamydia Trachomatis: The most common STI, causes veneral disease and eye infections.
E.Coli: Causes urinary tract infections (UTIs), traveler's diarrhea, and meningitis in children.
Mycobacterium Tuberculosis: Causes tuberculosis (TB).
Streptococcus: Causes pharyngitis, pneumonia, skin infections, and septicemia.
Stages of infection: Incubation period, prodromal stage, acute stage, and convalescent period.

Anti-Infective Drugs

Main goal: To assist the body in eliminating the pathogen.
Bactericidal: Kill bacteria.
Bacteriostatic: Prevent bacteria from replicating.
Bacterial cells have distinct differences from human cells, such as cell walls, biochemical pathways, and enzymes.
This difference helps antibiotics target bacterial cells without harming human cells (selective toxicity).
Acquired resistance: Bacteria can develop resistance to antibiotics through frequent mutations and replication.
Antibiotics promote the development of drug-resistant bacteria.
Widespread use of antibiotics: Leads to higher numbers of resistant bacterial strains.
MRSA and VRE: Examples of drug-resistant bacteria.
Preventing resistance: Use the right antibiotic for the right infection, restrict antibiotic use, and complete the full course of treatment.
Culture and sensitivity tests: Identify specific pathogens and test antibiotics’ effectiveness.
Severe infections: Begin with broad-spectrum antibiotics, then switch to narrow-spectrum antibiotics after lab results are available.
Common adverse effects: Secondary infections (superinfections).

Host Factors

Immunosuppression: Conditions like AIDS can weaken the immune system.
Site of infection: Infections in the central nervous system (CNS) or intracellularly can be more difficult to treat.
Allergies to certain drugs: Patients may have allergies to specific antibiotics.
Age, pregnancy, and genetics: Can influence infection susceptibility and antibiotic responses.

Antibiotics

Penicillins

Mechanism of action: Disrupt cell wall synthesis.
Effective against: Gram-positive bacteria that don't produce penicillinase.
Adverse effects: Nausea, vomiting, diarrhea, superinfections, anaphylaxis.
Contraindications: Hypersensitivity to penicillin class, severe renal disease.
Interactions: Potassium-sparing diuretics can cause hyperkalemia, decreases oral contraceptive effectiveness, and may interact with aminoglycosides (administer at least an hour apart).
Nursing considerations: Observe for possible reactions, provide allergy identification bracelets.

Cephalosporins

Mechanism of action: Inhibit cell wall synthesis.
Bactericidal.
Five generations: Each generation has a different spectrum of activity and resistance patterns.
Adverse effects: Rash, diarrhea, superinfections, seizures (rare).
Contraindications: Severe renal disease.
Interactions: Alcohol can cause a disulfiram reaction (violent vomiting).
Nursing considerations: Advise clients not to consume alcohol.

Tetracyclines

Mechanism of action: Inhibit bacterial protein synthesis.
Bacteriostatic.
Indications: Mountain spotted fever, typhus, cholera, Lyme disease, peptic ulcers caused by H.pylori, Chlamydial infection.
Adverse effects: Gastrointestinal distress (take with food), severe photosensitivity, tooth discoloration (avoid in children under 8 and pregnant women), hepatotoxicity.
Interactions: Milk products, iron supplements, magnesium-containing laxatives decrease effectiveness.
Nursing considerations: Administer orally (short half-life; four times a day), take with food and a full glass of water, intramuscular injection is painful, pregnancy category D.

Macrolides

Mechanism of action: Inhibit bacterial protein synthesis.
Bactericidal at high doses.
Effective against: A broad range of gram-positive and gram-negative bacteria.
Indications: Whooping cough, Legionnaires' disease, Listeria, Chlamydia, Neisseria, Legionella infections.
Adverse effects: Mild gastrointestinal upset, diarrhea, abdominal pain, superinfections.
Interactions: Anesthetics and anticonvulsants can increase toxicity, St. John's Wort decreases sensitivity.
Nursing considerations: Administer on an empty stomach with a full glass of water, no juices before or after.

Aminoglycosides

Mechanism of action: Inhibit bacterial protein synthesis.
Bactericidal.
Indications: Serious systemic infections caused by aerobic gram-negative organisms (E.Coli, Serratia, Proteus, Klebsiella, Pseudomonas).
Administration: Parenterally (IV or IM), poorly absorbed from the GI tract.
Adverse effects: Permanent ototoxicity and nephrotoxicity.
Nursing considerations: Monitor peak and trough levels.

Fluoroquinolones

Mechanism of action: Inhibit DNA synthesis by inhibiting two bacterial enzymes.
Bactericidal.
Effective against: Gram-negative bacteria, preferred for UTIs.
Administration: Well absorbed orally, once or twice a day.
Adverse effects: Nausea, vomiting, diarrhea, dysrhythmias, hepatotoxicity, increased risk of tendinitis and tendon rupture (Achilles tendon).
Nursing considerations: Notify doctor if leg pain.

Sulfonamides and Urinary Antiseptics

Mechanism of action: Inhibit folic acid synthesis.
Bacteriostatic.
Effective against: A broad spectrum of bacteria.
Indications: UTIs.
Adverse effects: Crystals in urine (increase fluid intake), nausea, vomiting, fatal blood abnormalities (monitor CBCs).
Contraindications: Renal impairment.
Nursing considerations: Administer oral doses with a full glass of water.

Glycopeptides

Vancomycin: Used for severe infections from gram-positive bacteria, especially MRSA infections.
Mechanism of action: Inhibits cell wall synthesis
Adverse effects: Ototoxicity, nephrotoxicity, Red Man Syndrome (rapid infusion), hypotension, flushing, rash (face, neck, trunk, upper body), superinfection.
Nursing considerations: Monitor peak and trough levels, administer slowly over a long period.

Tuberculosis

Latent TB: May reactivate if the immune system is suppressed.
Active TB: Involves lung infections and can spread to the bones.
Treatment: Six to twelve months of treatment with at least two (sometimes four or more) antibiotics, including isoniazid, rifampin, pyrazinamide, and ethambutol.

Isoniazid

Mechanism of action: Bactericidal and bacteriostatic.
First-line treatment for tuberculosis.
Adverse effects: Neurotoxicity (rash, fever, convulsions, dizziness, memory loss, psychoses).
Contraindications: Severe hepatic problems.
Interactions: Alcohol increases the risk of hepatotoxicity.
Nursing considerations: Administer on an empty stomach 1 hour after or 2 hours before meals, pregnancy category C, can cause vitamin B6 deficiency (monitor CNS health), may cause hyperglycemia.

Fungal Infections

Mechanism of action: Steroid used in plasma membranes affects ergosterol.
Causes: Inhalation of spores, handling contaminated soil.
Time to onset: Months before symptoms appear.
Transmission: Rarely transmitted through contact.
Types: Superficial (skin, nails, scalp, mouth, vagina) and systemic (internal organs).
Treatment: Topical treatments for superficial infections, aggressive oral or parenteral antifungals for systemic infections.

Amphotericin B

Mechanism of action: Broad-spectrum antifungal.
Preferred drug for systemic fungal infections.
Adverse effects: Fever, chills, vomiting, headache, phlebitis, nephrotoxicity, hypokalemia, cardiac arrest, hypotension, dysrhythmias, ototoxicity.
Contraindications: Renal impairment.
Interactions: Many drugs - check a drug guide.
Nursing considerations: Infuse intravenously slowly to reduce risk of cardiovascular collapse, administer premedication to decrease hypersensitivity risk, several months of therapy may be required.

Fluconazole

Mechanism of action: Interferes with ergosterol synthesis.
Minimizes infections from reaching the CNS.
Adverse effects: Nausea, vomiting, diarrhea, Steven-Johnson syndrome (with immunosuppression).
Contraindications: Pre-existing kidney disease.
Nursing considerations: Do not mix with other medications.

Nystatin

Superficial antifungal.
Mechanism of action: Binds to sterols in the fungal cell membrane.
Adverse effects: Topical: minor skin irritation; Oral: nausea, vomiting, diarrhea.
Administration: Topical or oral, too toxic for parenteral administration.

Protozoan Infections: Malaria

Protozoa: Single-celled organisms.
Malaria: Caused by Plasmodium.
Transmission: Mosquitoes inject Plasmodium, which multiplies in the liver and infects red blood cells.

Chloroquine

Mechanism of action: Effective against the erythrocytic stage of Plasmodium.
Adverse effects: Can reduce high fever.
Nursing considerations: Not effective against latent Plasmodium.

Infection Basics

Pathogenicity refers to how infectious an organism is, meaning its potential to cause infection.
Virulence describes how well an organism can produce disease, indicating its ability to cause harm.
Gram-positive bacteria retain the stain and appear purple, have thick cell walls, and are susceptible to penicillin which disrupts the cell wall.
Gram-negative bacteria do not retain the stain and appear pink, lack thick cell walls, and are often resistant to penicillin.
Bacteria can be classified by their shape: rod-shaped (bacilli), spherical (cocci), or spiral (spirilla).
Bacteria can be aerobic (use oxygen) or anaerobic (do not use oxygen).

Common Infectious Organisms

Chlamydia Trachomatis: The most common STI, causes venereal disease and eye infections.
E. coli: Causes UTIs, traveler's diarrhea, and meningitis in children. It produces toxins that can be dangerous.
Mycobacterium Tuberculosis: Causes tuberculosis (TB).
Streptococcus: Causes pharyngitis, pneumonia, skin infections, and septicemia.

Stages of Infection

Incubation period: The time between exposure to a pathogen and the onset of symptoms.
Prodromal stage: The initial appearance of mild, vague symptoms.
Acute stage: The period of maximum impact of the infectious process, characterized by severe symptoms.
Convalescent period: The period of recovery, marked by the containment of infection and resolution of symptoms.

Anti-Infective Medications

Goal: To assist the body in eliminating the pathogen.
Bactericidal: Kills bacteria directly.
Bacteriostatic: Prevents bacteria from replicating.
Antibiotics target structures and functions that are unique to bacterial cells, such as cell walls, biochemical pathways, and enzymes.

Antibiotic Resistance

Bacterial resistance is a significant problem, particularly due to the widespread use of antibiotics.
MRSA (Methicillin-Resistant Staphylococcus aureus) and VRE (Vancomycin-Resistant Enterococci) are examples of antibiotic-resistant bacteria.
Strategies to prevent resistance:
- Use the right drug for the right infection.
- Restrict antibiotic use.
- Complete the full course of therapy.

Culture and Sensitivity Tests (C&S)

Used to identify the specific pathogen causing an infection.
May take several days to weeks for results.
Determine which antibiotics are most effective against the identified pathogen.
For severe infections, broad-spectrum antibiotics should be initiated initially while awaiting C&S results. Once results are available, narrow-spectrum antibiotics can be used.
Common adverse effects: Secondary infections (superinfections).

Host Factors Influencing Infection

Immunosuppression: Conditions affecting the immune system, such as AIDS.
Site of infection: Infections in the CNS (central nervous system) and intracellular infections are often more challenging to treat.
Allergies: Allergies to specific drugs.
Age, pregnancy, genetics: Factors that can influence susceptibility and response to infection.

Penicillin

Mechanism: Disrupts bacterial cell wall synthesis.
Common adverse effects: Nausea, vomiting, diarrhea, superinfections, anaphylaxis (severe allergic reaction).
Contraindications: Hypersensitivity to penicillin, severe renal disease.
Important interactions:
- Potassium-sparing diuretics: Increased risk of hyperkalemia.
- Oral contraceptives: Decreased effectiveness.
- Aminoglycosides: Should be administered at least an hour apart.

Cephalosporins

Mechanism: Bactericidal, inhibits bacterial cell wall synthesis.
Generations: Five generations, with increasing resistance to breakdown by bacterial enzymes.
Common adverse effects: Rash, diarrhea, superinfections, seizures (rare).
Contraindications: Severe renal disease.
Important interactions: Alcohol can cause a disulfiram reaction (severe nausea and vomiting).

Tetracyclines

Mechanism: Bacteriostatic, inhibits bacterial protein synthesis.
Common uses: Mountain spotted fever, typhus, cholera, Lyme disease, peptic ulcers (H. pylori), chlamydial infections.
Common adverse effects: GI distress (take with food), photosensitivity (avoid sunlight), permanent teeth discoloration (do not give to children under 8 or pregnant women).
Contraindications: Pregnancy, children under 8, renal or hepatic impairment.
Important interactions: Milk products, iron supplements, magnesium-containing laxatives, oral contraceptives.

Macrolides

Mechanism: Inhibits protein synthesis.
Common uses: Whooping cough, Legionnaires' disease, listeria, chlamydia, neisseria, legionella.
Common adverse effects: Mild GI upset, diarrhea, abdominal pain, superinfections.
Important interactions: Anesthetics, anticonvulsants (increased risk of toxicity), St. John's wort (decreased sensitivity).

Aminoglycosides

Mechanism: Bactericidal, inhibits protein synthesis.
Common uses: Serious systemic infections caused by aerobic gram-negative organisms (E. coli, serratia, proteus, klebsiella, pseudomonas).
Administration: IV or IM, poorly absorbed from the GI tract.
Common adverse effects: Ototoxicity (hearing loss), nephrotoxicity (kidney damage).

Fluoroquinolones

Mechanism: Bactericidal, inhibits DNA synthesis.
Common uses: UTIs, respiratory infections.
Administration: Well absorbed orally, once or twice daily.
Common adverse effects: Nausea, vomiting, diarrhea, dysrhythmias, hepatotoxicity, increased risk of tendinitis and tendon rupture.

Sulfonamides and Urinary Antiseptics

Mechanism: Bacteriostatic, inhibits synthesis of folic acid, essential for bacterial growth.
Common uses: UTIs.
Common adverse effects: Crystals in urine (increase fluid intake), nausea, vomiting, blood abnormalities (monitor CBC).
Contraindications: Renal impairment.

Glycopeptides (Vancomycin)

Mechanism: Bactericidal, inhibits bacterial cell wall synthesis.
Common uses: Severe infections caused by gram-positive bacteria, particularly MRSA infections.
Common adverse effects: Ototoxicity, nephrotoxicity, "Red Man Syndrome" (flushing, rash), superinfection.
Important considerations: Peak and trough levels should be monitored to ensure therapeutic effectiveness and minimize toxicity.

Tuberculosis Treatment

Treatment duration: At least 6-12 months.
Drug regimen: Typically includes 2 or more antibiotics (isoniazid, rifampin, pyrazinamide, ethambutol).

Isoniazid

Mechanism: Bactericidal and bacteriostatic, inhibits synthesis of mycolic acid, a component of the Mycobacterium tuberculosis cell wall.
Common adverse effects: Neurotoxicity (convulsions, dizziness, memory loss, psychosis), rash, fever.
Contraindications: Severe hepatic problems.
Important interactions: Alcohol increases the risk of hepatotoxicity.
Important considerations: Can cause vitamin B6 (pyridoxine) deficiency, which should be monitored.
Potential side effect: Hyperglycemia.

Fungal Infections

Treatment: Antifungal medications, often required for prolonged periods.

Amphotericin B

Mechanism: Broad-spectrum antifungal, binds to ergosterol, a component of fungal cell membranes.
Common uses: Systemic fungal infections.
Common adverse effects: Fever, chills, vomiting, headache, phlebitis (inflammation of veins), nephrotoxicity, hypokalemia, cardiac arrest, hypotension, dysrhythmias, ototoxicity.
Contraindications: Renal impairment.
Important considerations: Administer IV slowly due to risk of cardiovascular collapse. Administer premedication to minimize hypersensitivity reactions.

Fluconazole

Mechanism: Inhibits the synthesis of ergosterol.
Common uses: Variety of fungal infections.
Common adverse effects: Nausea, vomiting, diarrhea, Steven-Johnson Syndrome (rare, but serious skin reaction).
Contraindications: Pre-existing kidney disease.

Nystatin

Mechanism: Binds to sterols in fungal cell membranes.
Common uses: Superficial fungal infections.
Common adverse effects: Topical: Minor skin irritation; Oral: Nausea, vomiting, diarrhea.
Important consideration: Not generally suitable for parenteral administration.

Protozoan Infections: Malaria

Causative organism: Plasmodium
Transmission: Mosquitoes.
Disease progression:
- Plasmodium enters the bloodstream through a mosquito bite.
- Plasmodium multiplies in the liver and transforms into progeny.
- Progeny infect red blood cells (RBCs), causing them to rupture.

Chloroquine

Mechanism: Interferes with the heme complexing process, essential for Plasmodium survival within red blood cells.
Common uses: Treatment of malaria in the erythrocytic stage (when the parasite is within red blood cells).
Important consideration: Not effective against the latent stage (dormant parasites in the liver).

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Test your knowledge on infection, pathogenicity, and virulence. This quiz covers the differences between gram-positive and gram-negative bacteria, their characteristics, and the concept of aerobic and anaerobic bacteria. Challenge yourself with questions that focus on various pathogens, including E.Coli and Chlamydia Trachomatis.