Quantitative Analysis of Gentamicin, Azithromycin, Telithromycin, Ciprofloxacin, Moxifloxacin, and Oritavancin (LY333328) Activities against Intracellular Staphylococcus aureus in Mouse J774 Macrophages

Abstract

Using J774 macrophages, the intracellular activities of gentamicin, azithromycin, telithromycin, ciprofloxacin, moxifloxacin, and oritavancin (LY333328) against Staphylococcus aureus (strain ATCC 25923) have been quantitatively assessed in a 24-h model. S. aureus was positively localized in phagolysosomes by confocal and electron microscopy, and extracellular growth was prevented with 0. . Intracellular activity was not directly correlated to extracellular activity as measured in broth. Conditions of pH 5 (i.e., mimicking that of phagolysosomes) markedly reduced the activity of gentamicin, azithromycin, and telithromycin (>32؋) and fairly extensively reduced that of ciprofloxacin and moxifloxacin (>4؋) but did not affect oritavancin activity. We conclude that the cellular accumulation of antibiotics is not the only parameter to take into account for intracellular activity but that local environmental conditions (such as pH) and other factors can also prove critical.Staphylococcus aureus, a ubiquitous pyogenic bacterium, is causing severe infections in humans as well as in animals (63). S. aureus adheres to and easily invades nonprofessional as well as professional phagocytes (1, 33). In the latter cells, S. aureus tends to be restricted to the phagolysosomal compartment, where it largely escapes destruction and survives in a semiquiescent state for prolonged periods (29, 52). These intraphagocytic forms are considered responsible for the well-known recurrent character of staphylococcal infections as well as for the many failures of apparently appropriate antibiotic treatments (16,27,36). The main and most current treatment option for S. aureus infections is the administration of a ␤-lactam resistant to ␤-lactamases (often combined with an aminoglycoside and/or rifampin) (61). Clindamycin and fusidic acid are second-line antibiotics for treatment of these infections. Glycopeptides, oxazolidinones, or synergistins are recommended for multiresistant strains only (47). Yet it is usually recognized that ␤-lactams are poorly active against the intracellular organisms because of their lack of cellular accumulation (56, 59). A number of models have therefore been developed to assess the potential of other antibiotics, such as rifampin, clindamycin, or glycopeptides (2, 12, 34), against intracellular S. aureus. Antibiotics with known cellular accumulation such as macrolides (23,38,48,60), synergistins (17), or fluoroquinolones (3, 4, 10, 46, 50) have also been studied. While providing useful information, these models have so far been used to examine only short periods of incubation and have not fully taken into account (i) the slow rate of intracellular accumulation of some antibiotics (see reference 57 for comments) and (ii) the reduced growth rate of intracellular S. aureus in comparison with that of bacteria in broth or other more favorable media (29). Moreover, contamination by bacteria growing extracellularly has often proven difficult to control (36).We present here data obtained with a model of S. aureusinfected J...

Simultaneous lack of catalase and beta-toxin in Staphylococcus aureus leads to increased intracellular survival in macrophages and epithelial cells and to attenuated virulence in murine and ovine models

“…These cells retain the ability to display a respiratory burst and are quite permissive towards a variety of intracellular pathogens (Day et al, 2000;Seral et al, 2003). Intracellular viability of the mutants and the wildtype strain in J774A.1 cells was determined over a period of 24 h. All strains exhibited a decrease in the number of viable bacteria after phagocytosis (Fig.…”

Intracellular pharmacodynamics of antibiotics

“…Those bacteria, like Listeria monocytogenes, multiply actively once having reached the cytosol (interferon-c maintains Listeria in phagosomes and lysosomes and thereby limits severely its multiplication [4] because of continuing exposure to oxygen and nitrogen reactive species [5]). Bacteria Opportunist Macrophages, PMNs Phagolysosomes [109][110][111] that gain access to phagolysosomes have a different fate. Generally speaking, lysosomes and phagolysosomes can be considered as acidic compartments poor in nutrients (iron depletion [6], tryptophan degradation [7]).…”

Lipoglycopeptide Antibacterial Agents in Gram-Positive Infections: A Comparative Review

“…Against intracellular bacteria infecting THP-1 cells (native monocytes or differentiated in macrophages), oritavancin appears to be the most effective of all the antibacterials tested in this model, reaching a true intracellular bactericidal effect (-3 log 10 decrease in bacterial counts), as demonstrated against intracellular MSSA [68,69], MRSA, VISA (including strains collected from a patient with bacteremia) [70], or even small colony variants [71][72][73]. It also proved synergistic with other bactericidal antibacterials such as fluoroquinolones or rifampicin against small colony variants [74].…”