1. Eur J Clin Microbiol Infect Dis. 2014 Nov;33(11):2035-40. doi:
10.1007/s10096-014-2174-z. Epub 2014 Jun 15.

Penicillin susceptibility breakpoints for Streptococcus pneumoniae and their
effect on susceptibility categorisation in Germany (1997-2013).

Imöhl M(1), Reinert RR, Tulkens PM, van der Linden M.

Author information: 
(1)Institute of Medical Microbiology, National Reference Center for Streptococci,
University Hospital (RWTH) Aachen, Pauwelsstr. 30, Aachen, Germany,

Continuous nationwide surveillance of invasive pneumococcal disease (IPD) was
conducted in Germany. From July 1, 1997, to June 30, 2013, data on penicillin
susceptibility were available for 20,437 isolates. 2,790 of these isolates (13.7 
%) originate from patients with meningitis and 17,647 isolates (86.3 %) are from 
non-meningitis cases. A slight decline in isolates susceptible at 0.06 and 0.12
μg/ml can be noticed over the years. Overall, 89.1 % of the isolates had minimum 
inhibitory concentrations (MICs) of ≤0.015 μg/ml. In 2012/2013, the first three
isolates of Streptococcus pneumoniae with MICs of 8 μg/ml were found. The
application of different guidelines with other MIC breakpoints for the
interpretation of penicillin resistance leads to differences in susceptibility
categorisation. According to the pre-2008 Clinical and Laboratory Standards
Institute (CLSI) interpretive criteria, 5.3 % of isolates overall were
intermediate and 1.4 % were resistant to penicillin. Application of the 2008-2014
CLSI interpretive criteria resulted in 7.6 % resistance among meningitis cases
and 0.5 % intermediate resistance in non-meningitis cases. Referring to the
2009-2014 European Committee on Antimicrobial Susceptibility Testing (EUCAST)
breakpoints, 7.6 % of the isolates in the meningitis group were resistant to
penicillin. In the non-meningitis group, 6.1 % of the isolates were intermediate 
and 0.5 % were resistant. These differences should be kept in mind when
surveillance studies on pneumococcal penicillin resistance are compared.

PMID: 24930041  [PubMed - in process]