@article{DuskeClausKroneetal.2024,
  author    = {Duske, Helene and Claus, Heike and Krone, Manuel and L{\^a}m, Thi{\^e}n-Tr{\´i}},
  title     = {Prevalence of piperacillin/tazobactam resistance in invasive \(Haemophilus\) \(influenzae\) in Germany},
  series = {JAC-Antimicrobial Resistance},
  volume    = {6},
  journal   = {JAC-Antimicrobial Resistance},
  number    = {1},
  issn      = {2632-1823},
  doi       = {10.1093/jacamr/dlad148},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350424},
  year      = {2024},
  abstract  = {Background Haemophilus influenzae (Hi) is a Gram-negative bacterium that may cause sepsis or meningitis, treatment of which mainly includes β-lactam antibiotics. Since 2019 EUCAST breakpoints for piperacillin/tazobactam have been available. Little is known about the prevalence and mechanisms of piperacillin/tazobactam resistance in Hi. Objectives To provide reliable prevalence data for piperacillin/tazobactam resistance in Hi in Germany, to evaluate different antibiotic susceptibility testing methods and to examine possible resistance mechanisms. Methods According to EUCAST breakpoints, the MIC for piperacillin/tazobactam resistance is >0.25 mg/L. All invasive Hi in Germany from 2019 were examined by gradient agar diffusion (GAD) for piperacillin/tazobactam susceptibility. Piperacillin/tazobactam broth microdilution (BMD), piperacillin GAD on tazobactam-containing agar [piperacillin GAD on Mueller-Hinton agar with horse blood (MH-F)/tazobactam) and piperacillin/tazobactam agar dilution (AD) were used for confirmation. Phenotypic testing was complemented by ftsI sequencing. Results Piperacillin/tazobactam GAD resulted in 2.9\% (21/726) resistant Hi. BMD did not confirm piperacillin/tazobactam resistance. Two strains were found resistant by AD, of which one was also resistant using piperacillin GAD on MH-F/tazobactam. Overall, we found two strains with a piperacillin/tazobactam MIC >0.25 mg/L in at least two different tests (0.3\%). Both were β-lactamase-producing amoxicillin/clavulanate-resistant with PBP3 mutations characterized as group III-like+. Relevant PBP3 mutations occurred in six strains without phenotypic piperacillin/tazobactam resistance. These mutations suggest a reduced efficacy of β-lactam antibiotics in these isolates. Conclusions Piperacillin/tazobactam resistance prevalence in invasive Hi is low in Germany. Reduced susceptibility was correlated with PBP3 mutations, in particular with group III mutations.},
  language  = {en}
}