O slideshow foi denunciado.
Utilizamos seu perfil e dados de atividades no LinkedIn para personalizar e exibir anúncios mais relevantes. Altere suas preferências de anúncios quando desejar.

Wound infections

colonization, interpretation of cultures

  • Entre para ver os comentários

Wound infections

  1. 1. RAJESH KUMAR R S
  2. 2.  The accumulation of pus, either within an abscess or exuding from a sinus tract or from a mucocutaneous surface, is one of the cardinal indicators of local sepsis.  Redness, pain and swelling
  3. 3.  Liable to contamination from body surface & environment  Contaminants relatively low numbers  Infection occurs if contaminants evades the host’s defence  Multiplication of commensal may be colonization  Virulence and resistance determines infection
  4. 4.  Exogenous Wound Infections  Endogenous Wound Infections
  5. 5.  Source of infection is outside the body of the patient.  Traumatic injury Decubitus pressure ulcers Animal or Human bites Burns Foreign bodies
  6. 6.  Caused by organisms that have been leading a commensal existence elsewhere in the patient’s body.  Surgical or post operative sepsis.  Nosocomial
  7. 7.  Staphylococcus aureus,Streptococcus pyogenes, pneumococcus and coliform bacilli.  Anaerobic organisms involved in soiled deep or lacerated wounds and devitalized tissues present.  Gas gangrene and tetanus  Mixed infections  Pathogenic synergy
  8. 8.  Ill, bed ridden patient  Anaerobic conditions because of tissue necrosis  Most of these lesions are located near the anus or on the lower extremities  Infection with bowel flora  Chronic infection  Bacteremia  B. fragilis, Clostridia sp, Enteric bacteria, S. aureus and P. aeruginosa.
  9. 9.  CDC group EF-4  Weeksella zoohelcum  Pasteurella spp  Staphylococcus intermedius  Staphylococcus aureus  Simonsiella  Capnocytophaga canimorsus
  10. 10.  Pseudomonas sp  Klebsiella sp  Proteus sp  E. coli  Clostridia sp  Aeromonas hydrophila
  11. 11.  Streptobacillus moniliformis  Spirillum minus
  12. 12. AEROBES:  α haemolytic streptococci  S. aureus  Streptococcus pyogenes  Eikenella corrodens
  13. 13. ANAEROBES:  Peptostreptococcus  Prevotella oris  Prevotella buccae  Porphyromonas sp  Fusobacterium nucleatum
  14. 14.  Bacteremia  Significant mortality  Interfere with the acceptance of skin grafts.  4 types – Impetigo, Surgical infections, Cellulitis, Systemic infections  Factors that contribute to infection include loss of skin barrier, coagulated proteins, loss of vascularity, dehydration & immune response  S. aureus, P.aeruginosa, Enterococci, Enterobacter sp & E. coli.  Candida, Aspergillus niger, Fusarium, Mucor  Herpes simplex
  15. 15.  Chronic osteomyelitis  S. aureus, Enterobacteriaceae, P. aeruginosa  Anaerobic GNB & GPC  Actinomycosis  Actinomyces spp., Aggregatibacter actinomycetemcomitans, P. propionicum, Prevotella & Porphyromonas  Tuberculosis, atypical mycobacteria, Nocardia  Implanted foreign bodies  Curettings or biopsy
  16. 16.  Problems in terms of collection  Perirectal fistula in Crohn’s disease  Bowel involvement only culture of specific key organisms like mycobacteria or Actinomyces are meaningful.  Biopsy
  17. 17. AEROBES:  S. aureus  CONS  Streptococcus pyogenes  Streptococcus anginosus  E. coli, klebsiella sp  Enterococcus sp  Proteus, Morganella & Providencia sp  Pseudomonas sp
  18. 18. ANAEROBES :  Clostridium spp  Peptostreptococcus spp  Bacteroides spp  Prevotella  Porphyromonas  Fusobacterium FUNGI :  Candida spp
  19. 19. SPECIMENS :  Wound swab  Pus or exudate  Fragments of excided tissue removed at wound toilet or Curettings  Biopsy  Blood
  20. 20. Physician should be urged that when a special investigation is required, they should state this clearly on the request form.Thus the routine investigation is usually confined to a search for the common pyogenic bacteria and anaerobic pathogens and does not include an examination for mycobacteria, actinomyces, nocardia, diphtheria, anthrax or fungi
  21. 21.  Naked Eye Examination  Microscopy  Culture  Gas Chromatography
  22. 22.  Staphylococci - thick creamy pus  Strep. Pyogenes – straw colored & watery  Proteus – fishy smell  Pseudomonas – sweet,musty odour & a blue pigment  Anaerobes – offensive, putrid smell  Actinomycosis – sulphur granules  Mycetoma – black or brown granules  Amoebic abscess – anchovy sauce
  23. 23.  Presence of relative numbers of polymorphs and bacteria  Morphology and arrangement  Wet film – fungi or motile bacteria - fluid aspirated from inflamed joint resembling septic arthritis may show uric acid crystals - Dark ground microscopy  Ziehl Neelsen or Fluorescent staining – AFB  Immunofluorescent staining – Clostridia species  Hematoxylin & Eosin – viral inclusions
  24. 24.  Blood agar – aerobic - anaerobic  MacConkey agar or CLED Agar  Cooked Meat Broth  PNPG Blood Agar  Firm agar  Special media
  25. 25.  Culture plates are examined after overnight incubation at 37º C  Relative number and type of colonies noted  If there is no growth, the plates should be reincubated for another 24 h.  If A. Israeli or Bacteroides suspected, plates incubated for 7 days  If turbid, the broth should be subcultured
  26. 26.  Difficulty in culture of slow growing anaerobes that are highly sensitive to oxygen.  Their still invisible growth may be killed by exposure to air during examination.  Anaerobic cabinet  Inoculated on two anaerobic plates
  27. 27.  Difficult in mixed cultures  Scanty growth of CONS, diptheroids are not reported  E.Coli from perineal wound etc are not reported.  Physician informed in case of Clostidium perfringens.  In chronic superficial lesions, the presence of mixed commensal bacteria can be disregarded as insignificant  Pure growth of commensal type organism grown from deep sites(eg.pleural fluid) should be reported with sensitivities, unless the number of the organism is so small as to indicate they are contaminants.
  28. 28.  Numerous or predominant organism is pathogenic.  Relative number of colonies may not reflect the number of organism in lesion.  Variations such as relative speed of growth of different species under the cultural conditions used, the presence of traces of antibacterial drugs , and the greater tendency of delicate pathogens to die during transport  Colonies in subculture from broth bears no relation to the number of organism in lesion.  Discussion with the physician.
  29. 29.  Significance of isolates  Predict the likelihood of burn wound sepsis  Probability of wound healing  Tissue weighed, homogenized, diluted serially, and inoculated into multiple agar plates.  S.pyogenes are clinically significant, no matter what the quantity of bacteria present.  >105 CFU/g is considered significant in burns  Single biopsy of a wound will not give an accurate picture of the microbial flora of chronic wound
  30. 30.  Buchanan et al  0.1(10-1) & 0.01(10-2 ) ml of sample in blood agar in duplicate  The number of CFUs per gram of tissue is calculated using the formula: Number of CFUs counted * Reciprocal of volume of homogenate inoculated(10-1or 10-2 ) * volume of diluent used for tissue homogenization /weight of tissue

×