Efficacy of lasalocid against murine Pneumocystis carinii pneumonitis

The antimicrobial and immunomodulatory effects of Ionophores for the treatment of human infection

Ionophores are a diverse class of synthetic and naturally occurring ion transporter compounds which demonstrate both direct and in-direct antimicrobial properties against a broad panel of bacterial, fungal, viral and parasitic pathogens. In addition, ionophores can regulate the host-immune response during communicable and non-communicable disease states. Although the clinical use of ionophores such as Amphotericin B, Bedaquiline and Ivermectin highlight the utility of ionophores in modern medicine, for many other ionophore compounds issues surrounding toxicity, bioavailability or lack of in vivo efficacy studies have hindered clinical development. The antimicrobial and immunomodulating properties of a range of compounds with characteristics of ionophores remain largely unexplored. As such, ionophores remain a latent therapeutic avenue to address both the global burden of antimicrobial resistance, and the unmet clinical need for new antimicrobial therapies. This review will provide an overview of the broad-spectrum antimicrobial and immunomodulatory properties of ionophores, and their potential uses in clinical medicine for combatting infection.

"Human babesiosis": an emerging transfusion dilemma

Babesiosis, a common disease of animals, can infect humans via vector "tick bite", particularly in endemic areas. The recent reports of fatal cases in Hepatitis C and postliver transplant patients resulting from transfusion of contaminated blood should alert the medical profession regarding this emerging dilemma in endemic as well as nonendemic areas and the need for accurate blood screening for transfusion. Here, we illustrate different stages of the parasite lifecycle, progression of babesiosis in animal model, some aspects of pathologic outcomes, ongoing therapeutic modalities, and a feasible Acridine Orange fluorescent methodology for the diagnostic evaluation of blood samples.

Polyether ionophores: broad-spectrum and promising biologically active molecules for the control of drug-resistant bacteria and parasites

BACKGROUND

As multidrug-resistant (MDR) pathogens continue to emerge, there is a substantial amount of pressure to identify new drug candidates. Carboxyl polyethers, also referred to as polyether antibiotics, are a unique class of compounds with outstanding potency against a variety of critical infectious disease targets including protozoa, bacteria and viruses. The characteristics of these molecules that are of key interest are their selectivity and high potency against several MDR etiological agents.

OBJECTIVE

Although many studies have been published about carboxyl polyether antibiotics, there are no recent reviews of this class of drugs. The purpose of this review is to provide the reader with an overview of the spectrum of activity of polyether antibiotics, their mechanism of action, toxicity and potential as drug candidates to combat drug-resistant infectious diseases.

CONCLUSION

Polyether ionophores show a high degree of promise for the potential control of drug-resistant bacterial and parasitic infections. Despite the long history of use of this class of drugs, very limited medicinal chemistry and drug optimization studies have been reported, thus leaving the door open to these opportunities in the future. Scifinder and PubMed were the main search engines used to locate articles relevant to the topic presented in the present review. Keywords used in our search were specific names of each of the 88 compounds presented in the review as well as more general terms such as polyethers, ionophores, carboxylic polyethers and polyether antibiotics.

Short-term exposure to membrane-active antibiotics inhibits Cryptosporidium parvum infection in cell culture

A cell culture system and double fluorogenic staining were used to study the susceptibility of Cryptosporidium parvum to membrane-active antibiotics. Buforin II and magainin II exerted a cytotoxic effect on sporozoites but did not consistently affect oocyst viability. Lasalocid and nigericin demonstrated less activity against sporozoites but reduced the infectivity of oocysts.

Anticryptosporidial activity of ranalexin, lasalocid and azithromycin alone and in combination in cell lines

The in vitro anticryptosporidial activities of ranalexin, lasalocid and azithromycin alone and in combination were investigated against four clinical isolates of Cryptosporidium parvum. Susceptibility was tested by inoculating the isolates on to cell monolayers and determining the parasite count after 48 h incubation at 37 degrees C. The culture medium was supplemented with Dulbecco's modified Eagle's medium containing serial dilutions of the above-mentioned compounds. Ranalexin showed moderate anticryptosporidial activity: at a concentration of 64 mg/L it reduced parasite counts by 33.8%. Azithromycin at a concentration of 8 mg/L gave inhibition comparable to that observed with the highest concentration of ranalexin. Lasalocid showed the highest activity, with a 70.3% reduction in parasite counts at 2 mg/L. The combination of ranalexin 64 mg/L and lasalocid 2 mg/L completely suppressed parasite growth without harming the monolayer.

Evaluation of drug efficacy by using animal models or in vitro systems

The efficacy of most therapeutic and prophylactic protocols against Pneumocystis carinii pneumonia used in human patients has been tested in animal models, especially in the corticosteroid-treated rat. The advantages and drawbacks of this model have been examined in brief in Chapter 1 of this section. More recently, the nude rat, intratracheally inoculated with Pneumocystis, was used to test new anti-microbian molecules for their anti-Pneumocystis activity. In vitro systems, co-cultures of Pneumocystis with feeder cells as well as axenic cultures, were also used many times for drug screening. In this paper, the most used in vivo or in vitro drug screening systems are described. Moreover, as immunocompromised individuals, AIDS patients, especially, are often infected simultaneously by several infectious agents, a recent co-infection model is described.