| Activity versus C. acnes
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Sarecycline exhibits in-vitro activity against C. acnes that is comparable to doxycycline and minocycline based on minimum inhibitory concentrations (MIC) for 50% (MIC50) and 90% (MIC90) bacterial growth inhibition.22,26
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C. acnes displays a low propensity for emergence of strains resistant to sarecycline, with spontaneous mutation frequencies being 10-10 at 4-8 x MIC (similar to minocycline).20,22
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Sarecycline demonstrated activity against high-level macrolide/erythromycin resistant C. acnes, similar to other TCNs.22,26
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| Activity versus bacteria that inhabit the human intestinal tract microbiome |
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Bacterial organisms of the human intestinal microbiome include some gram-negative organisms, such as Enterobacteriacea and Escherichia species, and some gram-positive organisms, such as Enterococcus species. Resistant strains of these families of bacteria are often relevant clinically. They are recognized therapeutic challenges when they are the causative organisms of a variety of infections that are not generally seen in dermatology practice, however, they are encountered within other medical disciplines.
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Compared to other TCNs, sarecycline exhibits a decreased spectrum of antibiotic effect against bacteria that inhabit the GI tract with a 16- to 32-fold decrease in activity against gram-negative bacilli and a 4- to 8-fold reduction in activity against anaerobic bacteria.22
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Sarecycline exhibits limited activity against Enterococcus spp and Enterobacteriaceae which is favorable in avoiding reduced selection pressure against these organisms found in the GI tract.22
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Sarecycline was much less active against E. coli as compared to other TCNs, with an MIC50 of 16 µg/mL compared to 1-2 µg/mL for TCN, doxycycline, and minocycline.22
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| Activity versus gram-positive bacteria |
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Sarecycline was shown to be active against TCN-resistant gram-positive bacteria (i.e., tetK and tetM strains) with low MICs of 0.125-1.0 µg/mL and 0.8 µg/mL, respectively.22
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Sarecycline is active against S. aureus and S. epidermidis, including methicillin-resistant isolates, with low MIC90 values of 0.5 and 2 µg/mL, respectively, and exhibits greater antibiotic activity than tetracycline and doxycycline against S. haemolyticus.22
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In single-step resistance studies, sarecycline showed low spontaneous mutation frequencies for methicillin-sensitive S. aureus (10-9) and S. epidermidis (10-8) at 4- and 8-fold x MIC (both similar to vancomycin).22
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Sarecycline antibiotic activity was tested against several gram-positive anaerobic bacteria, including Clostridium difficile, C. perfringens, Lactobacillus spp, Peptostreptococcus spp, and Bifidobacterium spp. Overall, compared to activity results with doxycycline and minocycline, sarecycline exhibited a 4- to 8-fold reduced antibiotic potency against these isolates.22
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| Activity versus other gram-negative bacteria |
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Testing of clinical isolates of Klebsiella pneumoniae and Proteus mirablis showed that sarecycline was largely inactive.22
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Among clinical isolates obtained in 2015–2016 in patients between 11 and 40 years of age, sarecycline exhibited much lower or absent antibiotic activity than other TCNs against several gram-negative bacteria (including many found in the GI tract) including E. coli, Klebsiella spp, Citrobacter freundii, P. mirablis, Enterobacter spp, and Morganella morganii.
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