Miller infections. One of the anticipated advantages of the new 8-methoxyﬂuoroquinolones was the increased activity (lower MICs) against resistant gram positive cocci. What has emerged among ocular and nonocular comparative studies is that the gap in improved coverage for resistant gram positive ocular pathogens is less than optimal (Kowalski et al 2003; Mather et al 2004; Miller et al 2006; Moshirfar et al 2006; Oliveira et al 2007). Pong et al evaluated the in vitro efﬁcacy of moxiﬂoxacin against clinical isolates with varying degrees of resistance to ciproﬂoxacin. There was a high correlation between increas- ing ciproﬂoxacin resistant levels and resistant MICs for both oﬂoxacin and moxiﬂoxacin for gram positive isolates. The comparative MICs, however, were lower for moxiﬂoxacin than for oﬂoxacin. In general moxiﬂoxacin MICs were 8- to 32-fold lower for gram-positive isolates and up to four fold lower for susceptible gram negative isolates than for the older ﬂuoroquinolones (Pong et al 1999). The improved activity of moxiﬂoxacin and gatiﬂoxacin against methicillin resistant S. aureus (MRSA) does not translated to in vivo efﬁcacy. No route of drug administration (oral, intravitreal, subconjunctival or topical) has provided concentrations that adequately cover the majority of MRSA with moderate or high level ciproﬂoxacin resistance. Kotulus and colleagues documented clinical failure in a subset of 9 patients with MRSA infections treated with moxiﬂoxacin or gatiﬂoxacin. A third of the patients improved with continued treatment with the 8-methoxyﬂuoroquinolones; however, two thirds needed additional therapeutic intervention and only improved when switched to vancomycin and or other combination therapy. Patients who failed therapy were treated for an average of 4.5 days, while the third with favorable outcomes were treated more long term (18.1 days) (Kotlus et al 2006). Others have also reported treatment failures for patients with MRSA. (Solomon et al 2003; Moshirfar et al 2006; Solomon et al 2007; Woodward and Randleman 2007). Coagulase-negative staphylococci remain the most fre- quent pathogen recovered from post cataract endophthalmitis. The consensus is that the origin of pathogens recovered from post cataract infections are seeded from the patient’s conjunctiva. Small populations of organisms resistant to the 8 methoxyﬂuoroquinolones may be presence as part of the resident conjunctiva ﬂora. These may have been “selected” following exposure to older ﬂuoroquinolone. The high concen- tration and broad spectrum of the ﬂuoroquinolone may disrupt normal conjunctival ﬂora and allow for colonization of more resistant bacterial and or more nonbacterial pathogens. 88 Mino de Kaspar and colleagues demonstrated a low rate of resistance (2%) among coagulase negative staphylococci in their study evaluating the normal conjunctiva ﬂora of patients scheduled for anterior segment surgery (Mino de Kaspar et al 2005). Miller et al documented a high level ﬂuoroquinolone cross resistance among coagulase negative endophthalmitis isolates. Increasing resistance to ciproﬂoxacin was paral- leled by increasing resistance to both moxiﬂoxacin and gatiﬂoxacin. Moxiﬂoxacin provides coverage for 10/38, 26% and gatiﬂoxacin 13/38, 66% for the ciproﬂoxacin-resistant isolates (Miller et al 2006). Role of moxiﬂoxacin in the management of ocular bacterial infections No anti-infective provides ideal coverage for all pathogens for all infected sites. 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