Use of highly active antiretroviral therapy in patients with renal insufficiency.

Antiretroviral agents, especially nucleoside reverse transcriptase inhibitors, require significant dosage adjustments in patients who have renal dysfunction and the human immunodeficiency virus (HIV). Some antiretroviral agents and fixed combination preparations are contraindicated in this population. In addition, many preferred antiretroviral regimens may be difficult to administer conveniently in patients with decreased creatinine clearance or in those receiving renal replacement therapies. Some highly active antiretroviral therapy regimens, however, can be used conveniently in patients with HIV and altered renal function.

Selecting antifungal agents for the treatment of invasive fungal infections in patients with renal failure.

The use of antifungal agents in patients with renal insufficiency requires careful consideration of not only the degree of renal insufficiency, but also other factors such as the fungal organism involved, site of infection and antifungal pharmacokinetics. Given the increase in the antifungal armamentarium, it is essential to have a comprehensive understanding of these agents to enable tailored therapy in this unique, but not uncommon patient population. This review will focus on the currently available data on this subject, providing guidelines for the use of antifungals in patients with renal failure.

Phenylpiperidine selective serotonin reuptake inhibitors interfere with multidrug efflux pump activity in Staphylococcus aureus.

Structural variants of phenylpiperidine selective serotonin reuptake inhibitors (P-SSRIs) inhibited the function of two unique Staphylococcus aureus multidrug efflux pumps. The most active compound was the paroxetine isomer NNC 20-7052, which had an IC(50) for ethidium, acriflavine, and pyronin Y efflux of 9, 53, and 18% of its MIC, respectively, against the NorA pump. The unbalanced effect of NNC 20-7052 on the efflux of different substrates suggests the possibility that P-SSRIs function by a physical interaction with NorA. Under the conditions employed pump inhibition partially extended to the resistance-nodulation-division (RND) pump AcrAB-TolC, but not to the Pseudomonas aeruginosa RND pumps MexAB-OprM or MexCD-OprJ.

Antifungal drugs in pregnancy: a review.

The use of any medication in pregnant women requires careful consideration of benefit to the mother versus risk posed to the fetus. Fungal infections are not uncommon in pregnant women; in fact, the incidence of certain infections such as Candida vaginitis is increased in this patient population. A variety of antimycotic agents are currently available to treat systemic or mucocutaneous fungal infections. Many of these agents are capable of penetrating the placental barrier and entering fetal cord blood, therefore adverse effects of these agents on the fetus are a valid concern. The use of topical azoles for the treatment of superficial fungal infections is safe and efficacious. However, there are some data suggesting a dose-related increase in the risk of teratogenicity associated with the use of systemic azoles. Amphotericin B remains the drug of choice for the treatment of systemic fungal infections in pregnancy. There are serious risks of fetal malformations associated with the use of griseofulvin, ketoconazole, voriconazole, flucytosine and potassium iodide. These drugs are contraindicated in pregnancy. There are insufficient data regarding the use of caspofungin in pregnancy. This article will review available data regarding the safety of antifungal drug use in pregnant women.

Phenothiazines and thioxanthenes inhibit multidrug efflux pump activity in Staphylococcus aureus.

Efflux-related multidrug resistance (MDR) is a significant means by which bacteria can evade the effects of selected antimicrobial agents. Genome sequencing data suggest that Staphylococcus aureus may possess numerous chromosomally encoded MDR efflux pumps, most of which have not been characterized. Inhibition of these pumps, which may restore clinically relevant activity of antimicrobial agents that are substrates for them, may be an effective alternative to the search for new antimicrobial agents that are not substrates. The inhibitory effects of selected phenothiazines and two geometric stereoisomers of the thioxanthene flupentixol were studied using strains of S. aureus possessing unique efflux-related MDR phenotypes. These compounds had some intrinsic antimicrobial activity and, when combined with common MDR efflux pump substrates, resulted in additive or synergistic interactions. For S. aureus SA-1199B, which overexpresses the NorA MDR efflux pump, and for two additional strains of S. aureus having non-NorA-mediated MDR phenotypes, the 50% inhibitory concentration (IC(50)) for ethidium efflux for all tested compounds was between 4 and 15% of their respective MICs. Transport of other substrates was less susceptible to inhibition; the prochlorperazine IC(50) for acriflavine and pyronin Y efflux by SA-1199B was more than 60% of its MIC. Prochlorperazine and trans(E)-flupentixol were found to reduce the proton motive force (PMF) of S. aureus by way of a reduction in the transmembrane potential. We conclude that the mechanism by which phenothiazines and thioxanthenes inhibit efflux by PMF-dependent pumps is multifactorial and, because of the unbalanced effect of these compounds on the MICs and the efflux of different substrates, may involve an interaction with the pump itself and, to a lesser extent, a reduction in the transmembrane potential.

Identification and characterization of a novel efflux-related multidrug resistance phenotype in Staphylococcus aureus.

Moxifloxacin is a C8-methoxy (C8-OMe) fluoroquinolone that is highly active against Staphylococcus aureus, including many strains resistant to older fluoroquinolones such as ciprofloxacin. Available data indicate that it is a poor substrate for the NorA multidrug efflux pump. We produced a mutant of S. aureus in vitro (SA-K2068) with a novel non-NorA-mediated multidrug resistance phenotype characterized by raised MICs of several fluoroquinolones, including the C8-OMe fluoroquinolones, moxifloxacin and gatifloxacin, and the organic cations ethidium and tetraphenylphosphonium. Reserpine reduced MIC increases by two- to eight-fold. SA-K2068 also demonstrated reduced accumulation of moxifloxacin, gatifloxacin and enoxacin, and increased efflux of ethidium, activities that were completely blocked by carbonyl cyanide m-chlorophenyl hydrazone (CCCP); competition experiments indicated that a single pump was responsible for the phenotype. The effect of CCCP and ionophores identified the proton motive force as the source of energy for efflux. These data, combined with previous work from our laboratory and genome sequence data, indicate that S. aureus possesses several multidrug efflux pump proteins and it is apparent that C8-OMe fluoroquinolones can be substrates for such pumps.