Lecture 4.ppt

Lecture 4.ppt

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  Vinnitsa National PirogovMemorial Medical University/ Department of microbiology Lecturer: ass.-prof.Vovk I.M. Main pathogens causing infectious arthritis, osteomyelitis. Laboratory diagnostics.
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  Infectious arthritis isan infection of one or more joints that can be caused by bacteria, viruses, fungi, and parasites It`s classified as: 1. Acute bacterial arthritis 2. Acute viral arthritis 3. Chronic infectious arthritis
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  Acute bacterial arthritis •Infection can be acquired from hematogenous dissemination, direct joint inoculation, or a contiguous focus. • Monoarticular mostly • Mainly the knee is affected Pathogens: 1. Staphylococcus aureus, Streptococcus spp. 2. Gram-negative bacteria ( in neonates, the elderly, intravenous drug users, and immunocompromised) 3. Neisseria gonorrheae in young adults, more often in females
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  Acute viral arthritis •As usually acute polyarticular arthritis that occurs simultaneously with other systemic symptoms of viral infection • Main pathogens: parvovirus B19, rubella virus, hepatitis B, hepatitis C, and alphaviruses, including chikungunya virus, Ross River virus, and o’nyongnyong virus
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  Laboratory diagnostics: synovialfluid assay A sample is taken during a procedure called an arthrocentesis Normal data: • Clear • Colorless or pale yellow • Stringy • Free of bacteria, viruses, and fungi • Cells: 0-150 cells/µL • Crystals: absent Arthritis: The synovial fluid may be cloudy or thick. • A high white blood cell count could mean you have an infection or another medical condition. • A high uric acid level and crystals could signal gout • A high red blood cell count could result from: – Injury – Blood in the joint – Bleeding disorder
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  Microscopy of synovialfluid Normal cells, found in synovial fluid: A- neutrophils; B-lymphocytes; C – monocytes/histiocytes; D – synovial lining cells Normally WBC in synovial fluid are presented by 48% monocytes,24% lymphocytes, macrophages 10%, neutrophils 7%, synovial cells 4%) Synovial fluid microscopy with acute inflammation signs: WBC up to 105, neutrophils are more then 50% Synovial fluid microscopy with septic arthritis: WBC up to 2x105, neutrophils are more then 90%
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  • Microscopy • Bacteriologicalinvestigation: – Gram stain – Culture method, antibiotic susceptibility tests • Molecular genetic assay at viral arthritis (PCR) • Other methods: plain film radiography. – computed tomography or magnetic resonance imaging is recommended.
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  Copied from MusculoskeletalKey: Synovial Fluid Analyses, Synovial Biopsy, and
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  Pathogen Prefered AntibioticAlternative Antibiotic Staphylococcus spp., Streptococcus spp., Enterococcus spp. Vancomycin Daptomycin or Linezolid Neisseria gonorrheae Ceftriaxone Cefotaxime Gram-negative non- fermentating rods Ceftazidime or Cefepime or Piperacillin-tazobactam Aztreonam or Ciprofloxacin (levofloxacin) or Dorepenem Risk factors for resistant pathogens Vancomycin + Ceftazidime or Cefepime Daptomycin or linezolid plus Piperacillin-tazobactam or Azteronam or Ciprofloxacin or Dorepenem Joint drainage by repeat aspiration, arthroscopy, or arthrotomy is required
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  Usually monoarticular Large peripheraljoints Mostly in immunocompomised or chronically ill patients Pathogens: Mycobacterium tuberculosis, atypical mycobacteria Fungi: Candida spp., dimorphic fungi (e.g., Blastomyces, Coccidioides, Histoplasma, and Sporothrix), Cryptococcus, and Aspergillus
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  • Therapy ofM. tuberculosis arthritis is similar to pulmonary tuberculosis. • Many fungal arthritides are difficult to treat and result in chronic joint disability. Treatment varies by infecting organism. Experience using the azoles (including new triazoles) and the echinocandins is growing, and in many cases, these drugs are replacing amphotericin. • Except for Cryptococcus and Sporothrix, fungal arthritis requires surgical drainage and débridement.
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  Osteomyelitis is aninflammation of the bone tissue caused by an infectious agent. It s can develop as the result of: 1. contiguous spread from adjacent soft tissues and joints ( diabetic foot infections, lesions at peripheral vascular disease 2. hematogenous seeding (more often in children), 3. direct inoculation of microorganisms into the bone as a result of trauma or surgery (open fracture, prosthesis or osteosynthesis). Classification: The Lew and Waldvogel classification is based on the duration of illness (acute versus chronic), the mechanism of infection (hematogenous vs. contiguous), and the presence of vascular insufficiency Acute osteomyelitis is associated with inflammatory bone changes caused by pathogenic bacteria, and symptoms typically present within two weeks after infection. Necrotic bone is present in chronic osteomyelitis, and symptoms may not occur until six weeks after the onset of infection, recurrent episodes are typical
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  A, B –acute osteomyelitis with abscess formation; C – sequestrum formation at chronic osteomyelitis
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  Acute osteomyelitis ismostly diagnosed in children because of hematogenous spreading. Hematogenous osteomyelitis is monomicrobial Contiguous osteomyelitis is polymicrobial and mostly diagnosed in adults High-risk groups: diabetes mellitus, vascular insufficiency Chronic osteomyelitis is resistant to therapy because of microbial biofilms formation on the bone tissue
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  • The diagnosisof osteomyelitis is suspected on clinical grounds. • Confirmation usually entails a combination of radiologic, microbiologic, and pathologic tests. • Computed tomography or magnetic resonance imaging (MRI), are considered standard of care in the diagnosis of osteomyelitis. • Bone biopsy or needle aspiration is best for organism identification (gold standard). • Repeated swab cultures of the same organism from draining wounds and sinus tracts may be of diagnostic benefit. Single investigation may be false-positive due to isolation of skin bacteria, also negative cultures are obtained in 50% of cases
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  S.aureus is themost common cause of hematogenous osteomyelitis in adults and children GAS (group A streptococci), Streptococcus pneumoniae and Kingella kingae took second place in children GBS (group B streptococci) may cause osteomyelitis in neonates Contiguous osteomyelitis may be caused by S.aureus, P.aeruginosa, Serratia marcescens, E.coli Fungi and mycobacteria can be isolated from immunocompomised and diabetes mellitus patients Propionibacterium acnes may be associated with osteomyelitis with osteosynthesis Salmonella spp. and other gram-negative bacteria may be cause of osteomyelitis in patients with hemoglobinopathies
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  Osteomyletis Main pathogensManagement Osteomyelitis after a contaminated open fracture Staphylococcus spp., gram-negative non- ferments early aggressive wound irrigation and débridement, administration of parenteral and local antimicrobials, fracture fixation, and soft tissue coverage of exposed bone. Vertebral osteomyelitis and spondylodiskitis S. aureus, coagulase- negative staphylococci, Mycobacterium tuberculosis, and Brucella spp. A 6-week course of parenteral antimicrobial therapy without surgery. Osteomyelitis in patients with diabetes mellitus or vascular insufficiency Polymicrobial a combination of broad-spectrum antimicrobial regimen and surgical débridement Acute hematogenous osteomyelitis S.aureus a 2- to 3-week course of antimicrobial therapy
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  Bacteria First lineAB Alternative AB Staphylococci (MSSA, MSSE) Oxacillin or cefazoline Vancomycin or rifampin Staphylococci (MRSA, MRSE) Vancomycin or Daptomycin Linezolid or levofloxacin plus rifampin Streptococci (penicillin sensitive) Penicillin G or ceftriaxone or cefazoline Vancomycin Enterococci Penicillin G or ampicillin plus gentamycin Vancomycin plus gentamycin Enterobacteria Ceftriaxone or ertapenem Ciprofloxacin or levofloxacin Pseudomonas aeruginosa Cefepime plus meropenem or imipenem Ciprofloxacin or ceftazidime
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  • Mandell, Douglasand Bennett`s Infectious Diseases Essentials, [edited by ] J.E.Bennett, R.Dolin, M.J.Blaser. -Elseiver, 2017. – 520 p. • Diagnosis and Management of Osteomyelitis/J. Hatzenbuehler, T J. Pulling//Am Fam Physician. 2011 Nov 1;84(9):1027-1033. • A.L.L. Lima et al. Recommendations for the treatment of osteomyelitis// Braz J Infect Dis. (2014). – Vol. 18 (5). 526-534. • Synovial Fluid and Synovial Fluid Analysis/ S.Watson// https://www.webmd.com/arthritis/synovial-joint-fluid-analysis • Synovial fluid analysis in the diagnosis of joint disease/P.Hermansen, T.Freemont//Diagnostic Histopathology (2017). – vol.23 (5). – 211-220. • N.Kavanagh et al. Staphylococcal Osteomyelitis: Disease Progression, Treatment Challenges, and Future Directions//Antimicrobial Agents and Chemotherapy (2018) https://doi.org/10.1128/CMR.00084-17