USING GENOTYPE TO COMBAT RESISTANCE: DEVELOPMENT OF A POTENTIAL TREATMENT AND SIMPLE PHENOTYPIC TEST DURING A 'PAN-RESISTANT' KLEBSIELLA PNEUMONIAE MINI-OUTBREAK. (February 2015)

• Record Type: Journal Article
• Authors: Brown, Jeremy; Brown, Mitchell; Ginn, Andrew; Agyekum, Alex; Fajardo-Lubian, Alicia; Iredell, Jon
• Is Part Of: Pathology. Volume 47(2015)Supplement 1
• Publication Date: 2015-02
• Subjects: Pathology -- Periodicals; 616.0705
• DOI: 10.1097/01.PAT.0000461603.30590.c4
• Languages: English
• ISSNs: 0031-3025

Abstract

Abstract : Aims: Aztreonam/clavulanic acid combination therapy is a potential treatment for multi-resistant Enterobacteriaceae containing MBLs and ESBLs. We describe an aztreonam/clavulanic acid based phenotypic detection and susceptibility test for MBL and ESBL-containing multi-resistant Enterobacteriaceae derived from initial genotypic characterisation. Methods: Three phenotypically pan-resistant (by Etest and automated broth microdilution) K. pneumoniae isolates from a clinical colonisation mini-outbreak were shown by PCR to contain MBL and ESBL β-lactamases. These isolates and thirteen other Enterobacteriaceae containing MBLs and ESBLs (with three also containing AmpC β-lactamases) were assessed for susceptibility to aztreonam/clavulanic acid by either broth microdilution or Etest, and our phenotypic disc-diffusion assay. β-lactamases were confirmed by multiplex PCR/reverse line blot. Results: Clavulanic acid restored susceptibility to aztreonam in all 'pan-resistant' outbreak isolates but not strains also carrying an AmpC β-lactamase. Our disc-diffusion assay predicted 16/16 MBLs, 15/16 ESBLs and 3/3 AmpC β-lactamases and showed susceptibility to aztreonam/clavulanic acid in all non-AmpC isolates. Discussion: Pan-resistant Gram-negative isolates are likely to become increasingly common. We have described a potential treatment for an initially phenotypically pan-resistant organism that was predicted from a genotype and developed a simple combined phenotypic detection and susceptibility test. Both potential treatment and test could be employed in resource poor settings.