Reduction in erythromycin resistance in invasive pneumococci from young children in England and Wales.

for gen. sp. 13BJ). The most noteworthy were the results for A. beijerinckii, A. junii and gen. sp. 13BJ. Whereas the former two species included both susceptible and resistant strains all eight strains of gen. sp. 13BJ yielded MICs 16 mg/L. It has recently been shown that therapy with colistin can be compromised by the selection and spread of colistin-resistant A. baumannii strains. Our data further indicate that resistance to colistin may be commonly present (A. junii, A. beijerinckii) in or even intrinsic (gen. sp. 13BJ) to some non-A. baumannii species. Although the colistin-resistant non-A. baumannii strains are rarely isolated from clinical specimens and these strains are usually susceptible to other antimicrobials (data on file), our findings emphasize the importance of precise species identification especially in reports on polymyxin resistance in Acinetobacter spp. Notably, resistance to colistin in A. baumannii has recently been associated with mutations in the PmrAB twocomponent system and it remains to be established whether this system also plays a role in the resistance of non-A. baumannii strains.