Cephalothin is not a reliable surrogate marker for oral cephalosporins in susceptibility testing of Enterobacteriaceae causing urinary tract infection

López, Itziar Angulo; Montes, Jorge; Álvarez, Mar Justel; Mazarrasa, Carlos Fernández; Martínez-Martínez, Luis

doi:10.1016/j.diagmicrobio.2016.08.017

Cited by 4 publications

(2 citation statements)

References 13 publications

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“…Using surrogates to infer or predict susceptibility is common in clinical practice with not only Streptococcus pneumoniae but essentially any bacterial pathogen that is susceptible to β-lactams [21][22][23][24]. It has previously been questioned with other pathogens, notably the Enterobacterales family to cephalosporins.…”

Section: Discussionmentioning

confidence: 99%

“…It has previously been questioned with other pathogens, notably the Enterobacterales family to cephalosporins. First-generation cephalosporins are similarly used to predict oral cephalosporins against Enterobacterales and has had conflicting results depending on the specific oral cephalosporin tested [ 22 , 23 ]. With a more recent study proposing routine use of oral cephalosporin, cefpodoxime, susceptibility testing to Enterobacterales as an optimal way to represent susceptibility to other oral cephalosporins (cefdinir, cefixime) [ 24 ].…”

Section: Discussionmentioning

confidence: 99%

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Predicting Oral Beta-lactam susceptibilities against Streptococcus pneumoniae

et al. 2021

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Background Oral beta-lactam antimicrobials are not routinely tested against Streptococcus pneumoniae due to presumed susceptibility based upon penicillin minimum inhibitory concentration (MIC) testing. Currently, Clinical and Laboratory Standards Institute provides comments to use penicillin MIC ≤0.06 to predict oral cephalosporin susceptibility. However, no guidance is provided when cefotaxime MIC is known, leading to uncertainty with interpretation. The purpose of this study was to evaluate cefotaxime and penicillin MICs and their respective correlation to oral beta-lactam categorical susceptibility patterns. Methods 249 S. pneumoniae isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF) and then tested by broth microdilution method to penicillin, cefotaxime, amoxicillin, cefdinir, cefpodoxime, and cefuroxime. Results Using Clinical and Laboratory Standards Institute (CLSI) non-meningitis breakpoints for cefotaxime, 240/249 isolates were classified as susceptible. Of the cefotaxime susceptible isolates, 23% of the isolates are misrepresented as cefdinir susceptible. Amoxicillin correlated well with penicillin MIC breakpoints with only 1 discordant isolate out of 249. Conclusion The correlation between amoxicillin and penicillin creates a very reliable predictor to determine categorical susceptibility. However oral cephalosporins were not well predicted by either penicillin or cefotaxime leading to the possible risk of treatment failures. Caution should be used when transitioning to oral cephalosporins in cefotaxime susceptible isolates, especially with higher cefotaxime MICs.

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Section: Discussionmentioning

confidence: 99%