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Questions and Answers
What is the most common bacterial pathogen associated with septic arthritis in adults?
What is the most common bacterial pathogen associated with septic arthritis in adults?
Which pathogen commonly causes early prosthetic joint infections?
Which pathogen commonly causes early prosthetic joint infections?
Which type of arthritis is most frequently associated with Neisseria gonorrhoeae in young sexually active patients?
Which type of arthritis is most frequently associated with Neisseria gonorrhoeae in young sexually active patients?
What classification is used for prosthetic joint infections occurring after 24 months?
What classification is used for prosthetic joint infections occurring after 24 months?
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What is a key feature of the pathogen Pasturella multocida?
What is a key feature of the pathogen Pasturella multocida?
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What is a major reason for the resistance of biofilm-associated bacteria to antibiotics?
What is a major reason for the resistance of biofilm-associated bacteria to antibiotics?
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In which patient population is Salmonella sp. considered a common pathogen for septic arthritis?
In which patient population is Salmonella sp. considered a common pathogen for septic arthritis?
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In children under 2 years, which organism is commonly found in joint infections?
In children under 2 years, which organism is commonly found in joint infections?
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How does Mycobacterium tuberculosis likely spread to the bones?
How does Mycobacterium tuberculosis likely spread to the bones?
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What is the typical microbiological characteristic of Neisseria gonorrhoeae?
What is the typical microbiological characteristic of Neisseria gonorrhoeae?
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What process allows bacteria within biofilms to communicate and coordinate their behavior?
What process allows bacteria within biofilms to communicate and coordinate their behavior?
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What is the most common cause of delayed prosthetic joint infections?
What is the most common cause of delayed prosthetic joint infections?
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Which organism is most likely to cause septic arthritis after trauma from a cat bite?
Which organism is most likely to cause septic arthritis after trauma from a cat bite?
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What type of necrosis is typically associated with Potts Disease?
What type of necrosis is typically associated with Potts Disease?
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What type of pneumonia is often tested for in cases involving children less than 1 month old?
What type of pneumonia is often tested for in cases involving children less than 1 month old?
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Which bacteria are primarily involved in the formation of biofilms on prosthetic materials?
Which bacteria are primarily involved in the formation of biofilms on prosthetic materials?
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What is the primary method for isolating pathogenic Neisseria?
What is the primary method for isolating pathogenic Neisseria?
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What is not a component of the triad associated with disseminated gonococcal infections?
What is not a component of the triad associated with disseminated gonococcal infections?
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Which organism is commonly involved in chronic arthritis in IV drug users?
Which organism is commonly involved in chronic arthritis in IV drug users?
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What is a characteristic of septic arthritis due to gonococcal infection?
What is a characteristic of septic arthritis due to gonococcal infection?
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What symptom is often associated with the second stage of Lyme disease?
What symptom is often associated with the second stage of Lyme disease?
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In the context of disseminated gonococcal infections, what type of immune reaction is thought to influence the symptoms?
In the context of disseminated gonococcal infections, what type of immune reaction is thought to influence the symptoms?
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Which of the following organisms is least likely to cause joint infections in individuals with leukemia?
Which of the following organisms is least likely to cause joint infections in individuals with leukemia?
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What feature distinguishes chronic Lyme disease in its persistent stage?
What feature distinguishes chronic Lyme disease in its persistent stage?
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Which pathogen is the most common cause of osteomyelitis overall, especially in pediatric patients?
Which pathogen is the most common cause of osteomyelitis overall, especially in pediatric patients?
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What characteristic of Staphylococcus aureus enhances its virulence in osteomyelitis?
What characteristic of Staphylococcus aureus enhances its virulence in osteomyelitis?
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In cases of vertebral osteomyelitis, which pathogen is primarily involved?
In cases of vertebral osteomyelitis, which pathogen is primarily involved?
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Which of the following are common bacterial causes of musculoskeletal infections?
Which of the following are common bacterial causes of musculoskeletal infections?
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What is the primary effect of the peptidoglycan found in the cell wall of Staphylococcus aureus?
What is the primary effect of the peptidoglycan found in the cell wall of Staphylococcus aureus?
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How do some strains of Staphylococcus aureus evade host defenses during osteomyelitis?
How do some strains of Staphylococcus aureus evade host defenses during osteomyelitis?
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Which of the following virulence factors are associated with Staphylococcus aureus in septic arthritis?
Which of the following virulence factors are associated with Staphylococcus aureus in septic arthritis?
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What type of bacteria are characterized by their resistance to immune responses and antibiotics when they grow as biofilms?
What type of bacteria are characterized by their resistance to immune responses and antibiotics when they grow as biofilms?
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Study Notes
Bone and Joint Infections Overview
- Bone and joint infections are a significant clinical concern
- Various pathogens cause these infections
- Identifying the specific pathogen is crucial for effective treatment
Osteomyelitis
- Learning Objectives: The learning objectives for the discussion of osteomyelitis are to identify the causative agents, describe the microbes' characteristics, and detail their virulence factors.
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Microbiology (Specific Pathogens):
- Staphylococcus aureus is the most common cause in both adults and children.
- Mycobacterium tuberculosis, potentially spreading from the lungs, can cause vertebral involvement (Pott's disease).
- Pasteurella multocida is a concern in cases related to cat or dog bites.
- Pseudomonas and Candida are connected to intravenous drug abuse.
Microbiology - Additional Information
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Gram-Positive Cocci (Bacteria): Staphylococcus aureus and Staphylococcus epidermidis
- Morphology and characteristics discussed
- Coagulase test
- Hemolysis and other bacterial testing
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Virulence Determinants (S. aureus):
- S. aureus binds to bone receptors (fibronectin, collagen, etc)
- Peptidoglycan, a component of the cell wall, stimulates monocytes and is crucial in causing septic arthritis
- Production of matrix metalloproteinases (MMPs) which degrade collagen
- Production of toxins like Toxic Shock Syndrome Toxin-1 (TSST-1) and enterotoxins implicated in arthritis.
- Leukocidins and hemolysins creating pores in leukocytes
Growth of Microbes in the Bone
- Bacteria, like S. aureus, develop biofilms in bones
- These are complex bacterial communities
- Biofilms are resistant to immune cells and antibiotics
- S. aureus can survive inside osteoblasts, avoiding host defenses and antibiotics
- Small Colony Variants (SCVs) of S. aureus in chronic osteomyelitis exhibit reduced energy production and antibiotic resistance
Tuberculosis of Vertebrae (Potts Disease)
- Mycobacterium tuberculosis spread through the bloodstream, infecting bones and joints
- Bacteria invade vascularized bone tissues
- Manifestations of the condition include vertebra collapse, disc extrusion, and caseating necrosis
Septic Arthritis due to Cat Bite (Pasturella multocida)
- Gram-negative facultative anaerobic coccobacilli
- Common commensals in animals, often transmitted via bites or scratches
- Capsule is a significant virulence factor
Microbiology and Other Infections
- Various fungi, like Candida, Blastomyces, Coccidioides, Cryptococcus, and Aspergillus, are possible bone and joint infection causes.
- Actinomyces (bacterial) and Sporothrix (fungal) infections often stem from traumatic inoculation.
- Bartonella henselae may be linked to HIV-related osteomyelitis
- Salmonella and S. aureus are involved in hematogenous osteomyelitis, especially in sickle cell disease.
Septic Arthritis
- The joint is frequently involved as is the knee and hip.
Learning Objectives (Overview)
- Identify the key bacterial organisms causing septic arthritis
- Understand the characteristics of the pathogens involved, and their virulence factors, when applicable
Etiology in Adults
- Knee and hip are the most frequent joints affected.
- Staphylococcus aureus is the most common cause.
- Other factors, like sickle cell disease, can influence the specific pathogens involved.
- Infections from trauma or puncture wounds may be caused by Pseudomonas sp..
- Acute monoarthritis can be caused by Neisseria gonorrhoeae in young sexually active individuals
Gonococcal Septic Arthritis
- Neisseria gonorrhoeae is the culprit in sexually active adults with disseminated infections.
- Gram-negative diplococcus (Shape)
- Disseminated infection from mucosal areas spreads to joints.
- Oxidative positive and produces the Cytochrome Oxidase enzyme.
- Specific growth media like Thayer-Martin is needed to isolate the causative agent
Gonococcal Septic Arthritis (Manifestations)
- Possible manifestations include tenosynovitis, dermatitis, and polyarthralgias without purulent arthritis in synovial fluid.
- Purulent arthritis without associated skin lesions is another possible form, with organisms found in joint fluid.
Lyme Disease
- Borrelia burgdorferi is the causative agent, transmitted through a blood meal from an infected Ixodes tick.
- Early symptom: Erythema migrans (bullseye rash)
- Dissemination results in possible migratory musculoskeletal pain, followed by arthritis, neurological problems, and/or carditis.
- Persistent infection can lead to chronic skin, nervous system, and/or joint abnormalities.
Etiology in Adults (After Trauma and Other Factors)
- Polymicrobial joint infections are a possibility after trauma.
- IV drug users may have sternoclavicular or sacroiliac joint infections (common organisms: Serratia marcescens and Pseudomonas aeruginosa).
- Leukemia patients may develop Aeromonas sp. infections.
- Fungal infections and Tuberculosis are rare, but important considerations in some cases
- Acid-fast smear of synovial fluid is often negative, but synovial biopsy in TB cases is positive in most cases
Etiology in Children
- For newborns or infants (<1 month), Group B Streptococcus (S. agalactiae), and gram-negative organisms and S. aureus are potential culprits.
- Children under 2 years, Haemophilus influenzae b (rare now due to vaccination), S. aureus, and Kingella kingae are frequent causes.
- Common infections in 3–15-year-old children are S. aureus and Streptococcus pyogenes.
Pathophysiology of Prosthetic Joint Infections
- Prosthetic joint infections are categorized as early, delayed, and late-onset infections (based on the time after implantation)
- Early infections stemming from direct inoculation often involve Staphylococcus aureus
- Delayed infections can be from gram-negative organisms or coagulase-negative Staphylococci
- Late infections are often hematogenous spread from various sites
Biofilms on Prosthetic Joints
- Biofilm formation on prosthetic materials is common
- Biofilms consist of complex aggregates of bacteria encased in a polysaccharide/DNA matrix and may include multiple species
- Quorum sensing allows bacteria communication within biofilms, contributing to resistance to antibiotics and immune system responses
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Description
Test your knowledge on the bacterial pathogens associated with various forms of arthritis, including septic arthritis and prosthetic joint infections. This quiz covers common organisms, characteristics, and antibiotic resistance mechanisms, providing insight into how infections develop and progress in patients.
