John and Harvin a smaller number of antibiotic combinations were active of evolving resistance, and only time will determine how against bioﬁlm-grown bacteria than against planktonic bac- rapidly resistance does emerge in the clinical arena. teria. Strains of S. lugdenensis in bioﬁlm have been shown to be particularly susceptible to moxiﬂoxacin, suggesting that some ﬂuoroquinolones do have good bioﬁlm activity (Frank et al 2007). In the same model, vancomycin was shown to be non-bactericidal, thus suggesting that bioﬁlm contributes to the phenomenon of tolerance or lack of killing in certain glycopeptides. The effects of antimicrobials seem to be different at the time of adherence versus the later stage of mature bioﬁlm formation. In a study to test interaction of speciﬁc agents with bioﬁlm, dicloxacillin was more active at both stages than cefazolin and vancomycin. Finally, bioﬁlm susceptibility may be staphylococcal species speciﬁc (Cerca et al 2005). An Argentine study looked at 5 CNS species and found that of 88 bioﬁlm producing strains, resistance to 2 or more agents was seen in 29% of S. haemolyticus, 24% of S. saprophyticus, and 20% of S. epidermidis (Gaudioso de Allori et al 2006). Such work implies that rapid evaluation of bioﬁlm-associated resistance should be integrated into clinical consideration. Furthermore, their in vitro ﬁndings can be translated into clinically applicable devices. Tigecycline and N-acetylcysteine have been embedded into vascular catheters. Such combinations are not only inhibitory of bioﬁlm growth in vitro but also act synergisti- cally against MRSA and MRSE (Aslam et al 2007). Concluding remarks Coagulase negative staphylococci comprise many species which have become increasing pathogenic to man by virtue of a changing host of demographics. CNS are relatively more resistant than their S. aureus counterparts but have fewer virulence factors. They do have a penchant for forming bioﬁlms on device materials and devitalized tissue, making bioﬁlm-associated CNS more resistant to penetration by anti- microbial agents. There are now good methods to show that bioﬁlms markedly increase the inhibitory concentration of standard antistaphylococcal agents. Hospital CNS have broad spectrum resistance and usually carry SCCmec cassettes that make their host resistant not only to β-lactam but a wide array of currently available antimicrobials. There are several newly marketed agents including linezolid, tigecycline, and dap- tomycin that have excellent activity against CNS including one species that is almost always pathogenic, S. lugdenesis. Other new, non-marketed agents including variations on vancomycin and new peptide agents show promise in vitro. Like their forebearers, however, there is always the spectre 1150 References Archer GL. 1978. 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