Background: Like other streptococci, Streptococcus agalactiae typically has intrinsic low-level aminoglycoside resistance. High-level gentamicin resistance was seen in 2 of 1125 isolates collected in the BSAC Bacteraemia Surveillance Programme between 2001 and 2014. These organisms, both isolated in 2014, were characterized. Methods: Identifications were by latex agglutination, MICs by BSAC agar dilution and sequencing by Illumina methodology. Results: Gentamicin MICs were .1024 mg/L versus a species mode of 8mg/L; both isolates also were unusually ciprofloxacin resistant with MICs of 64mg/L versus a species mode of 1mg/L. They were distinct by sequence, but both belonged to the ST19 clone, which occurs globally. Both had aac(60)-aph(200), carried by different transposons, explaining their gentamicin resistance, and had gyrA[81:S-L];parC[79:S-Y], accounting for ciprofloxacin resistance. Conclusions: These are the first multiresistant S. agalactiae with the bifunctional AAC(60)-APH(200) enzyme to be reported in the UK for .10 years. Despite belonging to the same clonal complex, the two isolates and their resistance transposons were distinct. Both retained full susceptibility to penicillin, but any penicillin/gentamicin synergy is likely to be lost.
Bibliographical noteFunding Information:
We are grateful to all the laboratories that have contributed isolates to the BSAC Bacteraemia Surveillance Programme, to Professor Paul Heath, Professor Alan Johnson, Professor Mike Sharland and Dr Theresa Lamagni for helpful discussions on the clinical significance of resistant GBS and to Roger Daniel and Chenchal Dhami of PHE for their work in extracting DNA for sequencing. The BSAC Bacteraemia Surveillance Programme was funded by many pharmaceutical companies during the 14 years reviewed here. A full listing is available at http://www.bsacsurv.org/about/sponsors-2/. Additional characterization and sequencing of the isolates was funded internally by Public Health England (PHE).
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