1: Antimicrob Agents Chemother. 2008 Sep;52(9):3040-6. Epub 2008 Jun 23. Cooperation between prokaryotic (Lde) and eukaryotic (MRP) efflux transporters in J774 macrophages infected with Listeria monocytogenes: studies with ciprofloxacin and moxifloxacin. Lismond A, Tulkens PM, Mingeot-Leclercq MP, Courvalin P, Van Bambeke F. Unité de Pharmacologie Cellulaire et Moléculaire, Université Catholique de Louvain, Brussels, Belgium. Antibiotic efflux is observed in both eukaryotic and prokaryotic cells, modulating accumulation and resistance. The present study examines whether eukaryotic and prokaryotic fluoroquinolone transporters can cooperate in the context of an intracellular infection. We have used (i) J774 macrophages (comparing a ciprofloxacin-resistant cell line overexpressing an MRP-like transporter with wild-type cells with basal expression), (ii) Listeria monocytogenes (comparing a clinical isolate [CLIP21369] displaying ciprofloxacin resistance associated with overexpression of the Lde efflux system with a wild-type strain [EGD]), (iii) ciprofloxacin (substrate of both Lde and MRP) and moxifloxacin (nonsubstrate), and (iv) probenecid and reserpine (preferential inhibitors of MRP and Lde, respectively). The ciprofloxacin MICs for EGD were unaffected by reserpine, while those for CLIP21369 were decreased approximately fourfold (and made similar to those of EGD). Neither probenecid nor reserpine affected the moxifloxacin MICs against EGD or CLIP21369. In dose-response studies (0.01x to 100x MIC) in broth, reserpine fully restored the susceptibility of CLIP21369 to ciprofloxacin (no effect on EGD) but did not influence the activity of moxifloxacin. In studies with intracellular bacteria, reserpine, probenecid, and their combination increased the activity of ciprofloxacin in wild-type and ciprofloxacin-resistant macrophages in parallel with an increase in ciprofloxacin accumulation in macrophages for EGD and an increase in accumulation and decrease in MIC (in broth) for CLIP21369. Moxifloxacin accumulation and intracellular activity were consistently not affected by the inhibitors. A bacterial efflux pump may thus actively cooperate with a eukaryotic efflux transporter to reduce the activity of a common substrate (ciprofloxacin) toward an intracellular bacterial target. PMID: 18573933 [PubMed - in process] Related Links Cellular accumulation and activity of quinolones in ciprofloxacin-resistant J774 macrophages. [Antimicrob Agents Chemother. 2006] PMID:16641436 Influence of P-glycoprotein and MRP efflux pump inhibitors on the intracellular activity of azithromycin and ciprofloxacin in macrophages infected by Listeria monocytogenes or Staphylococcus aureus. [J Antimicrob Chemother. 2003] PMID:12697643 Comparative activity of quinolones (ciprofloxacin, levofloxacin, moxifloxacin and garenoxacin) against extracellular and intracellular infection by Listeria monocytogenes and Staphylococcus aureus in J774 macrophages. [J Antimicrob Chemother. 2005] PMID:15731197 Influence of efflux transporters on the accumulation and efflux of four quinolones (ciprofloxacin, levofloxacin, garenoxacin, and moxifloxacin) in J774 macrophages. [Antimicrob Agents Chemother. 2005] PMID:15917543 Active efflux of ciprofloxacin from J774 macrophages through an MRP-like transporter. [Antimicrob Agents Chemother. 2004] PMID:15215125