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BSAC recommendations for interpreting the susceptibility of urinary tract isolates

BSAC recommendations for interpreting the susceptibility of urinary tract isolates. Jenny Andrews. UTIs. Frequency of micturition Dysuria Urgency Suprapubic pain Pyrexia Pyelonephritis. Bacterial causes of UTIs. Non-bacterial causes of UTIs. Simple UTIs. Women of child-bearing age

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BSAC recommendations for interpreting the susceptibility of urinary tract isolates

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  1. BSAC recommendations for interpreting the susceptibility of urinary tract isolates Jenny Andrews BSAC User Group Meeting 2007

  2. UTIs • Frequency of micturition • Dysuria • Urgency • Suprapubic pain • Pyrexia • Pyelonephritis BSAC User Group Meeting 2007

  3. Bacterial causes of UTIs BSAC User Group Meeting 2007

  4. Non-bacterial causes of UTIs BSAC User Group Meeting 2007

  5. Simple UTIs • Women of child-bearing age • E. coli • P. mirabilis • Klebsiellae • Enterococci • S. saprophyticus • Group B Streptococci BSAC User Group Meeting 2007

  6. Prevalence of organisms isolated from samples taken in the community (female) City Hospital data BSAC User Group Meeting 2007

  7. Complicated UTIs • Male patients • Abnormal anatomy • Catheterisation • Children • Immunocompromised patients • Elderly BSAC User Group Meeting 2007

  8. Microbial causes • Enterobacteriaceae • Non-fermenters • Staphylococci • Enterococci • Antibiotic-resistant strains frequently isolated BSAC User Group Meeting 2007

  9. UTI in men Wallach, 2001; McMurdo and Gillespie, 2000 BSAC User Group Meeting 2007

  10. Conditions associated with or predisposing to lower UTI in men • Prostatitis/Prostate enlargement (common in older men) • Abnormal urinary tract, anatomical changes,calculi and tumours • Impaired host defences • Impaired renal function Bailey 1996 BSAC User Group Meeting 2007

  11. UTI in men – organisms associated with infection • E.coli the most common pathogen in acute and chronic prostatitis • Klebsiella spp. and P. mirabilis isolated less frequently • Hospital acute cases may involve staphylococci and occasionally enterococci or Pseudomonas spp BSAC User Group Meeting 2007

  12. Prevalence of organisms isolated from samples taken in the community (male) City Hospital data BSAC User Group Meeting 2007

  13. Laboratory diagnosis • Mid Stream Urine • Low epithelial cell count • Pyuria/haematuria • Semi-quantitative culture • 105 cfu/ml bacteria considered significant • Identification (some laboratories do not ID urine isolates) and susceptibility testing BSAC User Group Meeting 2007

  14. BSAC: Systemic recommendationsNon-species specific Table 6: MIC and zone breakpoints for Enterobacteriaceae (including Salmonella and Shigella spp.). BSAC User Group Meeting 2007

  15. BSAC: Species specific breakpoints for simple UTIs NB. These recommendations are for organisms associated with uncomplicated urinary tract infections. For complicated infections systemic recommendations should be used. BSAC User Group Meeting 2007

  16. BSAC: Species specific breakpoints for simple UTIs NB. These recommendations are for organisms associated with uncomplicated urinary tract infections. For complicated infections and infections caused by Staphylococcus aureus and Staphylococcus epidermidis, which are associated with more serious infections, systemic recommendations should be used. BSAC User Group Meeting 2007

  17. Organism Identification • Essential for interpretation of susceptibility • Chromogenic media BSAC User Group Meeting 2007

  18. Chromogenic agar (6570 UTI) Klebsiella-Enterobacter-Serratia 28.6% Proteus-Morganella-Providencia 6.9% 72.5% Data presented by Trevor Winstanley at User Group meetings in 2005 (Power Point presentation available on the BSAC web site (www.bsac.org.uk) BSAC User Group Meeting 2007

  19. Footnotes to the UTI tables BSAC User Group Meeting 2007

  20. BSAC recommendations • The recommendations are for organisms associated with uncomplicated urinary tract infections • For complicated infections systemic recommendations should be used • For infections caused by S. aureus and S. epidermidis, which are associated with more serious infections, systemic recommendations should be used BSAC User Group Meeting 2007

  21. BSAC recommendations • If an organism is isolated from multiple sites, for example from blood and urine, interpretation of susceptibility should be made with regard to the systemic site. • Direct susceptibility tests on urine may be performed as long as the inoculum gives semi-confluent growth. BSAC User Group Meeting 2007

  22. BSAC recommendations • In the absence of definitive organism identification, use the recommendations most appropriate for the presumptive identification, accepting that on some occasions the interpretation may be incorrect. A more cautious approach is to use systemic recommendations BSAC User Group Meeting 2007

  23. BSAC recommendations • The identification of Enterobacteriaceae to species level is essential before applying expert rule for the interpretation of susceptibility e.g. recommendations for ampicillin/amoxicillin are for E. coli and P. mirabilis not for species that have chromosomal penicillinase (Klebsiella spp.) or those that typically have inducible AmpC enzymes (e.g. Enterobacter spp., Citrobacter spp. and Serratia spp.) BSAC User Group Meeting 2007

  24. Under review by EUCAST/BSAC • Use of trimethoprim for the treatment of enterococci • The clinical efficacy of mecillinam in the treatment of ESBL infections BSAC User Group Meeting 2007

  25. Gaps in the “Coliform” recommendations • “Coliform” means like an E. coli, the recommendations should not be used for Enterobacter spp. etc. • ID to species level is essential for the correct interpretation BSAC User Group Meeting 2007

  26. Should nalidixic acid be used to detect FQ resistance? • Using nalidixic acid alone 25-40% of isolates with LLR will be reported resistant to ciprofloxacin • Organisms with LLR are probably susceptible in uncomplicated infections because of the high concentration of drug in urine BSAC User Group Meeting 2007

  27. Summary • BSAC urinary breakpoints are for simple UTIs • For complicated infections systemic recommendations should be used • ID is necessary for the interpretation of susceptibility and the application of expert rules (see the Power Point presentation on the BSAC web site for the User Group Meeting in 2005 Trevor Winstanley “Expert rules and inexpensive identification methods”) • EUCAST are preparing a document on expert rules that should be available at the end of the year BSAC User Group Meeting 2007

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