Are resistance rates among bloodstream isolates a good proxy for other infections? Analysis from the BSAC Resistance Surveillance Programme

Carolyne Horner, Shazad Mushtaq, Michael Allen, Christopher Longshaw, Rosy Reynolds, David M Livermore

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Background: Bacteraemia data are often used as a general measure of resistance prevalence but may poorly represent other infection types. We compared resistance prevalence between bloodstream (BSI) and lower respiratory (LRTI) isolates collected by the BSAC Resistance Surveillance Programme.
Methods: BSI isolates (n=8912) were collected during 2014 - 2018 inclusive and LRTI isolates (n=6280) between Oct 2013 to Sept 2018 from participating laboratories in the UK and Ireland, to a fixed annual quota per species group. LRTI isolates, but not BSI, were selected by onset: community for Streptococcus pneumoniae; hospital for Staphylococcus aureus, Pseudomonas aeruginosa, Enterobacterales. MICs were determined centrally by agar dilution; statistical modelling adjusted for ICU location and possible clustering by collection centre. 
Results: Resistance was more prevalent among the LRTI isolates, even after adjusting for a larger proportion of ICU patients. LRTI P. aeruginosa and S. pneumoniae were more often resistant than BSI isolates for most antibiotics, and the proportion of MRSA was higher in LRTI. For S. pneumoniae, the observation reflected different serotype distributions in LRTI and BSI. Relationships between LRTI and resistance were less marked for Enterobacterales, but LRTI Escherichia coli were more often resistant to beta-lactams, particularly penicillin/beta-lactamase inhibitor combinations, and LRTI Klebsiella pneumoniae to piperacillin/tazobactam. For Enterobacter cloacae there was a weak association between LRTI, production of AmpC enzymes and cephalosporin resistance. 
Conclusions: Estimates of resistance prevalence based upon bloodstream isolates underestimate the extent of the problem in respiratory isolates, particularly for P. aeruginosa, S. pneumoniae, S. aureus and, less so, for Enterobacterales.
Original languageEnglish
Article numberdkab096
Number of pages10
JournalJournal of Antimicrobial Chemotherapy
Early online date5 Apr 2021
DOIs
Publication statusE-pub ahead of print - 5 Apr 2021

Keywords

  • antibiotics
  • penicillin
  • bacteremia
  • intensive care unit
  • lactams
  • proxy
  • infections
  • lower respiratory tract infections
  • piperacillin/tazobactam
  • methicillin-resistant staphylococcus aureus
  • surveillance program
  • bloodstream infections
  • community
  • serotype

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