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Questions and Answers
Which of the following bacteria is commonly associated with food poisoning and gastrointestinal infections?
What disease is caused by Clostridium botulinum?
Which organism is linked to urinary tract infections and meningitis?
Which of the following bacteria is primarily responsible for causing pertussis?
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Identify the bacteria responsible for causing pneumonia and upper respiratory infections.
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What type of infection is primarily associated with Escherichia coli?
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Which of these bacteria is associated with nosocomial infections?
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Which bacteria are known to be involved in causing pink eye?
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Which organism is known for being resistant to all ß-lactam antibiotics and aztreonam?
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What is the primary purpose of active surveillance testing for multidrug-resistant organisms?
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Which antibiotic class can effectively treat infections caused by organisms that produce Klebsiella pneumoniae carbapenemase (KPC)?
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Approximately what percentage of community-acquired staphylococcal infections are due to MRSA?
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Which factor is considered the most significant method of preventing healthcare-associated infections?
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Why are newer antibiotics developed for treating MRSA and VRE?
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What is a potential consequence of MRSA becoming resistant to all available antibiotics?
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Which of the following infections is primarily associated with Vancomycin-resistant Enterococcus (VRE)?
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What distinguishes gram-positive bacteria from gram-negative bacteria?
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How do bacteria damage host tissues during an infection?
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What role do exotoxins play in bacterial infections?
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Which morphological type of bacteria is rod-shaped?
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What condition allows non-pathogenic bacteria to become harmful?
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What is the main characteristic of prokaryotes such as bacteria?
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Which statement about systemic infections is accurate?
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What factor primarily influences the choice of antibiotic therapy for a bacterial infection?
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Which of the following is NOT a typical sign of infection?
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What is the impact of a compromised host defense system on infection risk?
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Study Notes
Systemic Signs and Symptoms
- Pain and swelling
- Increased WBC
- Formation of pus
Common Disease-Causing Bacteria
-
Clostridium organisms
- C. botulinum: Food poisoning with progressive muscle paralysis
- C. difficile: Diarrhea, colitis
- C. perfringens: Food poisoning, gangrene
- C. tetani: Tetanus (lockjaw)
- Corynebacterium diphtheriae: Diphtheria
- Escherichia coli: Urinary tract infections, cystitis, peritonitis, inflammatory gastrointestinal infections
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Haemophilus organisms
- H. aegyptius: Pink eye
- H. influenzae: Nasopharyngitis, meningitis, pneumonia, otitis media, upper respiratory tract infections
- H. pertussis: Pertussis (whooping cough)
- Helicobacter pylori: Peptic ulcers, gastritis
- Klebsiella and Enterobacter organisms: Urinary tract infections, peritonitis, pneumonia
- Proteus organisms: Urinary tract infections, meningitis
- Pseudomonas aeruginosa: Urinary tract infections, meningitis
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Salmonella organisms
- S. typhi: Typhoid fever
- Other Salmonella organisms: food poisoning, gastroenteritis
- Shigella organisms: Shigellosis, diarrhea with abdominal pain and fever (dysentery)
- Staphylococcus aureus: Skin infections, pneumonia, urinary tract infections, acute osteomyelitis, toxic shock syndrome
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Streptococcus organisms
- S. epidermidis: Nosocomial sepsis
- S. faecalis: Genitourinary infection, infection of surgical wounds
- S. pneumoniae: Pneumococcal pneumonia, otitis media
Infection
- Invasion of the body by a pathogen/microorganism
- Signs and symptoms develop in response to invasion
- Most common causes: bacteria, fungi, protozoa, viruses
- Classified as localized (limited to a small area) or systemic (widespread throughout the body, often spread via the blood)
Bacteria
- One-celled microorganisms found everywhere on earth
- Involved in fermentation, putrefaction, infectious diseases, and nitrogen fixation
- Can be harmful or beneficial:
- Non-pathogenic: Usually do not cause disease, part of normal flora, often beneficial
- Pathogens: Disease-causing microbes
Bacteria and Disease
- Bacteria can cause disease in two ways:
- They can enter the body and grow inside human cells: e.g., tuberculosis
-
They can secrete toxins that damage cells:
- Exotoxins: Usually produced by gram-positive bacteria
- Endotoxins: Present in the cell wall of gram-negative bacteria, released on death of bacterium, vasoactive compounds that can cause septic shock
- Enzymes: Damage tissues and promote the spread of infection
Bacteria: Morphology
- Bacteria take on different shapes (morphology)
- Grouped based on their shape:
- Bacilli: Rod-shaped organisms
- Spirochetes: Include spiral forms and vibrio
-
Cocci: Spherical forms
- Diplococci
- Streptococci
Bacteria: Classification
- Classified as prokaryotes
- No nuclear membrane, no nucleus
- Function metabolically and reproduce by binary fission
- Complex cell wall structure
- Do not require living tissues to survive
- Vary in size and shape
Bacteria: Gram Staining
- Most important categorization: Gram stain procedure
- Guides the choice of antibiotic therapy
- Gram-positive bacteria: Purple, thick cell wall, thick outer capsule
- Gram-negative bacteria: More complex cell wall structure, more difficult to treat, drug molecules have a hard time penetrating cell wall
Bacterial Infection
- Host defenses are compromised; susceptible to infection
- Microorganism invades and multiplies in body tissues
- Infectious process can overwhelm the body’s defense system
- Classic signs and symptoms: Fever, chills, sweating, redness
-
Different types of infection:
- Nosocomial infections (HAI): acquired in the healthcare setting (e.g., MRSA, VRE)
- Community-acquired infections: acquired outside of the healthcare setting
- Other sources of infection: Mechanical ventilators, intravenous infusion lines, dialysis equipment
Multidrug-Resistant Organisms (MDRO)
- Organisms resistant to one or more classes of antimicrobial drugs:
- Methicillin-resistant Staphylococcus aureus (MRSA)
- Vancomycin-resistant Enterococcus (VRE)
- Organisms producing extended-spectrum ß-lactamases (ESBLs)
- Organisms producing Klebsiella pneumoniae carbapenemase (KPC)
- Active surveillance testing by swabbing nares and/or rectal/perirectal area
- Purpose is to appropriately place colonized patients into contact precautions
Multidrug-Resistant Organisms (MDRO): MRSA
- Threat of MRSA becoming resistant to all antibiotics
- No longer only seen in hospitals, spread to community setting
- Approximately 50% of staphylococcal infections in the community involve MRSA
- VRE: Usually seen in urinary tract infections (UTIs)
Multidrug-Resistant Organisms: New Antibiotics
- Newer antibiotics developed to treat VRE and MRSA
Multidrug-Resistant Organisms: Extended-Spectrum ß-Lactamase (ESBL)
- Organisms producing ESBL are resistant to all ß-lactam antibiotics and aztreonam
- Can be treated only with carbapenems or sometimes quinolones
- Some bacteria have become resistant to carbapenems: Klebsiella pneumoniae
- Klebsiella pneumoniae carbapenemase (KPC)
- Treatment for difficult cases: tigecycline or colistimethate sodium
Health Care-Associated Infection (HAI)
- Over 70% of health care-associated infections are preventable
- Most commonly transmitted by direct contact
- Handwashing: The single most important method of prevention
- Disinfectants are essential
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Description
This quiz covers systemic signs and symptoms of bacterial infections as well as common disease-causing bacteria. It delves into specific bacteria such as Clostridium, Corynebacterium, Escherichia, and others, discussing their associated diseases. Test your knowledge and understanding of these important microbiological concepts.
