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Questions and Answers
Which organism is responsible for 80-90% of culture positive cases of osteomyelitis?
Which organism is responsible for 80-90% of culture positive cases of osteomyelitis?
In patients with a history of UTI or IV drug abuse, which organism is commonly associated with osteomyelitis?
In patients with a history of UTI or IV drug abuse, which organism is commonly associated with osteomyelitis?
Which type of infections would you expect from direct spread in osteomyelitis cases?
Which type of infections would you expect from direct spread in osteomyelitis cases?
Which organism has been found to commonly infect in the neonatal period in cases of osteomyelitis?
Which organism has been found to commonly infect in the neonatal period in cases of osteomyelitis?
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Patients with sickle cell disease are prone to osteomyelitis caused by which organism?
Patients with sickle cell disease are prone to osteomyelitis caused by which organism?
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Which organism is most commonly associated with septic arthritis in older children and adults?
Which organism is most commonly associated with septic arthritis in older children and adults?
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Which organism is specifically linked with septic arthritis in individuals with sickle cell disease?
Which organism is specifically linked with septic arthritis in individuals with sickle cell disease?
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Which bacteria are transmitted by deer ticks and can lead to Lyme arthritis?
Which bacteria are transmitted by deer ticks and can lead to Lyme arthritis?
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In which age group is Gonococcus primarily associated with septic arthritis?
In which age group is Gonococcus primarily associated with septic arthritis?
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What is a common finding in synovial fluid analysis for septic arthritis caused by Staphylococcus aureus?
What is a common finding in synovial fluid analysis for septic arthritis caused by Staphylococcus aureus?
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Which laboratory test is most pertinent for diagnosing Lyme arthritis?
Which laboratory test is most pertinent for diagnosing Lyme arthritis?
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What type of immune response is predominantly observed in patients with Borrelia burgdorferi infection?
What type of immune response is predominantly observed in patients with Borrelia burgdorferi infection?
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What type of joint involvement is characteristic of chronic Lyme disease?
What type of joint involvement is characteristic of chronic Lyme disease?
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What is the most likely causative organism for septic arthritis in a young, sexually active adult presenting with gram-negative diplococci in the synovial fluid?
What is the most likely causative organism for septic arthritis in a young, sexually active adult presenting with gram-negative diplococci in the synovial fluid?
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Which organism is least likely to cause septic arthritis in a sexually active young adult?
Which organism is least likely to cause septic arthritis in a sexually active young adult?
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What characteristic finding in the synovial fluid would indicate septic arthritis?
What characteristic finding in the synovial fluid would indicate septic arthritis?
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Which of the following conditions is characterized by the presence of purulent synovial fluid?
Which of the following conditions is characterized by the presence of purulent synovial fluid?
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What finding suggests that a patient with joint pain may not have reactive arthritis?
What finding suggests that a patient with joint pain may not have reactive arthritis?
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In a diagnosis of septic arthritis in a young male, which factor would support the suspicion of infection?
In a diagnosis of septic arthritis in a young male, which factor would support the suspicion of infection?
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Which organism is most likely associated with septic arthritis in individuals with a history of skin infections?
Which organism is most likely associated with septic arthritis in individuals with a history of skin infections?
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What distinguishes septic arthritis from rheumatoid arthritis based on synovial fluid analysis?
What distinguishes septic arthritis from rheumatoid arthritis based on synovial fluid analysis?
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Study Notes
Bone Infections
- Bone infections are a significant medical concern.
- Osteomyelitis is a complication of systemic infections or a primary solitary infection site.
- Organisms causing osteomyelitis include viruses, parasites, fungi, and bacteria.
- Pyogenic bacteria and mycobacteria are the most frequent causes.
Routes of Infection
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Pyogenic Infections:
- Hematogenous spread (common in children)
- Extension from a nearby site of infection
- Direct implantation (after injuries or procedures)
- Foot infections are common in diabetics.
- Long bones are commonly affected.
Causative Organisms
- Staphylococcus aureus is the most frequent causative agent (80-90% of cases).
- Urinary tract infections (UTIs) and intravenous drug abuse are associated with Escherichia coli, Pseudomonas, and Klebsiella.
- Other organisms, like Haemophilus influenzae and group B Streptococcus, have been linked to neonatal infections.
- Salmonella is a concern in individuals with sickle cell disease.
- Mixed bacterial infections can also occur.
Changes in Acute Osteomyelitis
- Neutrophilic inflammatory reaction: A key characteristic.
- Necrosis of bone and marrow: Within 48 hours.
- Periosteal inflammation: Often leads to subperiosteal abscesses, particularly in children.
- Ongoing necrosis: The previous factors impact this.
- Sequestrum: Dead bone.
- Sinus formation: A possible consequence.
- Septic arthritis: Potential complication, especially in infants' epiphyses.
Changes in Chronic Osteomyelitis
- Chronic inflammatory cells are present.
- Cytokines released, causing osteoclastic bone resorption.
- Fibrous tissue, reactive bone growth at periphery.
- Involucrum: Newly formed bone that surrounds dead bone.
- Marrow fibrosis, sequestrum, and inflammatory infiltrate of lymphocytes and plasma cells are histologic markers of chronic osteomyelitis.
Lab Tests in Acute Osteomyelitis
- CBC with differential (Leukocytosis): The white blood cell count and its classification.
- Elevated inflammatory markers (ESR, CRP): Erythrocyte sedimentation rate and C-reactive protein, indicative of inflammation.
- Cultures (ID and c/s): Identification and culture of pathogens.
- Bone aspirate cultures: Direct samples from the bone to identify pathogens.
- Bone biopsy (rare): A more invasive procedure if the above aren't diagnostic.
Acute Osteomyelitis Histopathology Findings
- Visual representations of acute inflammation and bone destruction in illustrative images.
- Images of live and dead bone cells.
- Images of inflammation in the bone tissue.
Gram Stain Microscopy
- Shows the morphology of pathogenic microorganisms to analyze the infection.
Chronic Osteomyelitis Imaging
- X-ray images showing a typical chronic osteomyelitis affecting the tibia (lower leg bone).
Draining Osteomyelitis Imaging
- Presentation of the involucrum and sequestrum.
Lab Tests in General (for various infections)
- Bone biopsy (H&E): Examination technique with staining.
- Microbiological cultures: Identifying specific pathogens.
- Special studies: If cultures are negative.
Chronic Osteomyelitis Histology
- Microscopic images demonstrating the pathologic features of chronic osteomyelitis, including the presence of mononuclear inflammatory cells and dead osteocytes.
Mycobacterial Osteomyelitis
- Incidence is higher in developing countries, but it's seen in developed countries as well.
- Often associated with pulmonary/extrapulmonary TB.
- Commonly indolent, presenting with localized pain, low-grade fevers, chills, and weight loss.
- Solitary/disseminated, specifically in immunocompromised patients.
- Histologic markers of caseous necrosis and granulomas.
- Tuberculous spondylitis (Pott disease) is a severe form, causing destructive vertebral infections.
Mycobacterial Osteomyelitis Lab Tests
- Smears: Examination technique.
- Special stains: Staining of microorganisms for detection.
- Cultures: Growing pathogens for specific identification.
- Molecular tests: Identifying a specific pathogen using DNA/RNA-based methods.
- Biopsy (rare): A more invasive procedure, generally for suspected rare conditions.
Tuberculous Osteomyelitis Microscopy
- Histologic images demonstrating various stages, including necrosis and giant cells.
Acid Fast Stain
- Illustrative image of acid-fast stain, showcasing the appearance of bacilli under microscopy.
Septic Arthritis
- Infection spread hematogenously, by direct inoculation, or from contiguous sites.
- Infectious arthritis is rapid and can lead to permanent joint damage.
- Specific organisms relate to age groups like H. influenzae occurring in children under two
- S. Aureus, Gonorrhea, and Salmonella relate to other age groups.
- Diagnostic method: joint aspiration
Septic Arthritis Lab Tests
- Complete Blood Count (CBC) with differential
- Inflammatory markers
- Blood cultures
- Synovial fluid aspiration (smears, stains, cultures - ID, c/s)
Lyme Arthritis
- Caused by infection by Borrelia burgdorferi, transmitted by ticks (Ixodes ricinus complex).
- Commonly affects New England and mid-Atlantic states.
- Initial symptoms may involve migratory arthritis (chronic stage.).
- Lab diagnosis: Tests for antibodies.
- Cellular responses to Borrelia outer surface protein A (late autoimmune arthritis).
- Histopathology includes synovial hyperplasia and fibrin deposition; mononuclear cell infiltrates and onionskin thickening of arterial walls.
Lyme Disease Lab Tests
- EIA or ELISA for total Lyme titer or IgG and IgM titers
- Western blot IgG and IgM titers (if initial tests are positive or inconclusive)
- Lyme titers should be conducted if prior tests are positive.
- PCR in synovial fluid
Lyme Arthritis Microscopic Images
- Microscopic images demonstrating a long corkscrew-shaped organism (Borrelia).
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Description
Test your knowledge on bone infections, specifically osteomyelitis, and the various routes and causative organisms associated with these infections. Gain insights into how systemic infections can lead to bone complications and the common microbes involved. This quiz is perfect for students studying medical or health-related subjects.
