Erschienen in:
16.09.2021 | Brief Report
Possible misinterpretation of penicillin susceptibility in Staphylococcus aureus blood isolate due to in vitro loss of the blaZ gene
verfasst von:
Helle Brander Eriksen, Andreas Petersen, Michael Pedersen, Søren Overballe-Petersen, Anders Rhod Larsen, Barbara Juliane Holzknecht
Erschienen in:
European Journal of Clinical Microbiology & Infectious Diseases
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Ausgabe 1/2022
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Abstract
We describe a case of recurrent catheter-related blood stream infections (BSI) with Staphylococcus aureus, in which the first isolate tested susceptible to penicillin, while subsequent isolates were resistant. Phenotypic susceptibility correlated with the absence/presence of the blaZ gene. The in vitro stability of penicillin resistance was investigated by subculturing single colonies. In two out of five colonies, phenotypical resistance was lost after a single subculture, which correlated with loss of the blaZ gene. This in vitro phenomenon probably resulted in a very major error in the microbiology report of the first BSI, where penicillin had been recommended as treatment.