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Which of the following types of pathogens can cause infections in humans?
What is the first process in the infection cycle of microorganisms?
Which of the following statements about viral infections is true?
Which type of treatment is effective against bacterial infections?
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What is a characteristic of the multiplication stage in the infection cycle?
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What is the ultimate effect of pathogen spread in the body?
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Which of the following can be considered a common type of antimicrobial agent?
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Which of these is a condition related to a viral infection that cannot be eradicated?
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Which of the following best describes the mechanism by which acyclovir inhibits viral replication?
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What characteristic differentiates Gram-positive bacteria from Gram-negative bacteria?
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What is the significance of the lipopolysaccharide layer in Gram-negative bacteria?
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Which type of bacteria would most likely fit the description of filamentous bacteria?
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Which bacterial shape is NOT categorized among the true bacteria?
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What component is NOT part of the LPS structure?
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Which type of bacteria retains the crystal violet dye during the Gram stain test?
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Which component of fungal cells provides resistance to certain antibiotics?
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What is the primary treatment for vaginal infections caused by Candida albicans?
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What defines bactericidal antibiotics?
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Which type of antibiotic acts against a limited group of bacteria?
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What characteristic is associated with Gram-negative bacteria?
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Which of the following antibiotics is used to treat scalp infections?
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What is a superinfection?
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Which of the following practices increases the risk of antibiotic resistance?
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Which bacteria is associated with antibiotic-related infections of the large intestine?
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What can trigger a problem with C.difficile in the bowel?
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What is the initial treatment step for a serious C.difficile infection?
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Which of the following is a potential consequence of a serious C.difficile infection?
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Which organism has shown resistance to tetracycline due to antibiotic overuse?
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What is a common outcome of recurrent C.difficile infections?
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What is the primary mechanism of action for macrolides?
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Which characteristic is true regarding the use of macrolides?
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What is a common adverse effect associated with macrolides?
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Why are macrolides often buffered or enteric coated?
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Which type of ribosome do aminoglycosides act upon?
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In what situation are macrolides typically used?
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What is a significant factor that determines whether macrolides are bactericidal or bacteriostatic?
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What suffix is commonly associated with both macrolides and aminoglycosides?
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Study Notes
Common Pathogens
- Viruses, bacteria, fungi, protozoa and worms are common pathogens.
- Some viral infections are lifelong and cannot be eradicated, such as HIV-1/HIV-2 and herpes simplex virus (HSV) infection.
- HSV-1 and HSV-2 are highly contagious and spread through contact and saliva.
- HSV-1 causes cold sores and HSV-2 causes genital herpes.
- Anti-viral drugs, such as acyclovir (Zovirax), are used to treat viral infections.
- Antibiotics cannot kill viruses.
Bacterial Infections
- Bacteria are categorized by their shape, arrangements, and gram staining.
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Shapes and Arrangements:
- Filamentous bacteria, such as Mycobacterium tuberculosis, form mycelium.
- True bacteria include cocci, bacilli, vibrio, and spirilla.
- Cocci can be arranged in pairs (diplococci), chains (streptococci), clusters (staphylococci), tetrads, or sarcinae (cube-like packets).
- Bacilli are rod-shaped bacteria.
- Vibrio are comma-shaped bacteria, such as Vibrio cholerae (cholera).
- Spirilla are helical or spiral-shaped bacteria.
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Gram Staining:
- Gram-positive bacteria have a thick layer of peptidoglycan in their cell walls and stain blue.
- Gram-negative bacteria have a thin layer of peptidoglycan and a lipopolysaccharide (LPS) coat in their outer membrane, staining pink.
- LPS, also known as endotoxin, consists of lipid A, a core polysaccharide, and an O antigen.
Fungal Infections
- Fungi have thick cell walls made of polysaccharides.
- They can exist as single-celled yeasts or multicellular molds/moulds.
- Fungal cell walls are resistant to antibiotics targeting bacterial cell walls, such as penicillin and cephalosporin.
- Fungi can adapt to various environments, including digesting keratin (found in skin, hair, and nails), and can suppress host immune defenses.
- Vaginal infections caused by Candida albicans can be treated with antifungal creams, suppositories, or tablets, such as butoconazole (Gynazole-1), clotrimazole (Gyne-Lotrimin), and fluconazole (Diflucan).
- Scalp infections can be treated with antifungal shampoos containing ketoconazole (Nizoral).
Types of Antibiotics
- Bactericidal: Antibiotics that kill bacteria.
- Bacteriostatic: Antibiotics that inhibit bacterial growth.
- Broad spectrum: Antibiotics that act against a large group of bacteria.
- Narrow spectrum: Antibiotics that act against a limited group of bacteria.
Mechanisms of Antibiotic Resistance
- Superinfection: A second infection caused by an antibiotic-resistant microbial agent that occurs on top of an earlier infection.
- Antibiotic overuse: Excessive use of antibiotics increases the chance of bacteria developing resistance.
- Pseudomonas can become resistant to cephalosporins.
- Candida albicans can become resistant to tetracycline.
Clostridium difficile Infection
- Clostridium difficile is a bacterium that causes infection in the large intestine (colon).
- C. difficile usually lives harmlessly in the bowel but can become problematic when the balance of bacteria is disrupted by antibiotics.
- Infection can cause high fever, diarrhea, stomachache, and loss of appetite.
- Serious C. difficile infection can lead to toxic megacolon and sepsis, potentially resulting in ICU admission and death.
- Treatment for C. difficile infection:
- Stop the current antibiotics, if possible.
- Begin a 10-day course of an antibiotic that targets C. difficile.
- If recurrent infection occurs more than twice, consider a fecal microbiota transplant.
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Description
This quiz covers essential topics related to common pathogens, including viruses, bacteria, fungi, protozoa, and worms. You'll learn about the characteristics of viral and bacterial infections, their classifications, and treatment options. Test your knowledge on infectious diseases and their causative agents.
