Robert A. Fromtling

Raltegravir: the first HIV-1 integrase strand transfer inhibitor in the HIV armamentarium.

Raltegravir is the first integrase strand transfer inhibitor approved for the treatment of HIV‐1 infection. As the first agent in this new class of antiretroviral therapies, raltegravir has demonstrated safety and efficacy in treatment‐naive as well as heavily pretreated HIV‐infected patients failing therapy with multidrug‐resistant virus. Raltegravir has a favorable drug interaction profile that permits both administration to a wide, demographically diverse patient population and coadministration with many other therapeutic agents, including antiretroviral agents and supportive medications, without restrictions or dose adjustment. Data through 96 weeks of follow‐up in three phase III studies, protocol 021 (STARTMRK) in treatment‐naive patients, and protocols 018 (BENCHMRK‐1) and 019 (BENCHMRK‐2) in treatment‐experienced patients, demonstrated the potent and durable antiretroviral and immunologic effects and the favorable long‐term safety profile of raltegravir in both treatment‐naive and treatment‐experienced patients. Raltegravir represents an important addition to the current armamentarium for the treatment of HIV infection.

An overview of macrophage-fungal interactions

A review of the literature (148 references) on the interactions of fungi with polymorphonuclear cells, monocytes and macrophages is presented. The interactions of Aspergillus species, Coccidioides immitis, Blastomyces dermatitidis, Histoplasma capsulatum, Cryptococcus neoformans, Candida albicans, and Candida species with human and experimental animal derived immune cells are examined in this overview. An effort has been made to present the reader with a comprehensive list of references with the intent of encouraging additional reading and research in this important area.

Isolation of saprophytic Cryptococcus neoformans from Puerto Rico: Distribution and variety

Until the present decade, no studies had been conducted in Puerto Rico on the saprophytic distribution and variety of Cryptococcus neoformans. Samples (522) of pigeon droppings from 14 western towns were tested for the presence of C. neoformans. The yeast was recovered from 24.7% (129 isolates) of the samples, representing 10 of the 14 towns studied. All environmental isolates were identified as C. neoformans var. neoformans using canavanine-glycine-bromthymol blue (CGB) agar. The yeast was isolated from 79.4% of the samples in one town, Isabela. The average number of yeast cells isolated from sites within this municipality was 5.1×105 per gram of pigeon droppings. This was 2.6 times the average number of yeast cells of C. neoformans isolated from sites in other towns. In addition, the yeast was isolated from four patients with the acquired immune deficiency syndrome (AIDS), each of whom died of cryptococcal meningitis. Each of these poorly encapsulated isolates was identified as C. neoformans var. neoformans using CGB agar. The results of this investigation demonstrate that C. neoformans var. neoformans is prevalent in Puerto Rico.

Virulence and antifungal susceptibility of environmental and clinical isolates of Cryptococcus neoformans from Puerto Rico.

Studies on the distribution, epidemiology and pathogenesis of Cryptococcus neoformans on the island of Puerto Rico are few. We have studied mouse virulence and in vitro antifungal susceptibility of 133 isolates of C. neoformans: 121 environmental and 12 clinical (9 from AIDS patients), that were isolated in Puerto Rico. In experimental CD-1 mice infected intravenously, the mean lethal dose 50% values (28 days) were > 5.2×106 and 1.1×105 cells/mouse for environmental and clinical isolates, respectively. Using an agar dilution assay, the minimum inhibitory concentrations of amphotericin B, ketoconazole and 5-fluorocytosine were comparable for environmental and clinical isolates in both yeast nitrogen dextrose base agar and Kimmigs agar. These data suggest a difference in lethality for mice, but no difference in antifungal susceptibility of environmental and clinical isolates of C. neoformans obtained in Puerto Rico.

Cryptococcus neoformans: comparisons of in vitro antifungal susceptibilities of serotypes AD and BC.

Thirty-nine isolates of Cryptococcus neoformans, nineteen serotype AD and twenty serotype BC, were assayed for susceptibility to eight antifungal agents using an in vitro agar dilution assay. Media employed were Kimmig agar and yeast nitrogen base supplemented with 10% glucose. The antifungal agents used were ketoconazole, amphotericin B, 5-fluorocytosine, nystatin, miconazole, BAY N 7133, ICI 153,066, and itraconazole. No clinically significant differences in in vitro minimum inhibitory concentrations were detected between serotypes AD and BC against any of the compounds tested. An adverse medium effect was observed in two of the assays, but the outcome of the AD/BC comparison was not affected. This is the first report in which the in vitro antifungal susceptibilities of Cryptococcus neoformans serotypes are analyzed.

Increasing usage of systemic antifungal agents

The frequency of invasive fungal diseases has increased substantially during the past two decades (Horn et al., 1985; Klimowski et al., 1989; Kovacs et al., 1985; Walsh and Pizzo, 1988). Immunocompromised patients including those receiving intensive treatment for neoplastic diseases, organ transplantation, or aggressive surgical interventions and those afflicted with the human immunodeficiency virus (HIV) are expanding patient populations with a high risk of developing opportunistic life-threatening fungal infections. Little is known about the effect of this increased frequency of invasive fungal infections upon usage of antifungal compounds. Moreover, attention has been generally applied toward the better known trends of increased usage of antibacterial agents. Evaluating the trends in usage of antifungal compounds may also yield important data concerning the epidemiology of mycoses. Understanding the patterns of increased usage of systemic antifungal agents may have important implications for the clinical microbiology laboratory for the need for monitoring flucytosine plasma levels, acquiring improved blood culture devices for detection of fungi (e.g., lysis centrifugation), and eventual implementation of standardized antifungal susceptibility techniques. Such data on the trends of usage of antifungal agents also have important implications of infection sur-

Yeasts and fluconazole susceptibility in the Philippines

Identification and fluconazole susceptibility of 579 yeasts isolated from patients in 16 medical centers throughout the Philippines in 1997–98 is reported. Speciation revealed the following distribution of yeasts (with percent occurrence): Candida albicans (49.6%); C. parapsilosis (17.2%);C. tropicalis (14.9%); C. glabrata(6.2%); C. pelliculosa (4.3%); C. krusei(2.4%); C. guilliermondii (1.9%); Trichosporon cutaneum (1.7%); Cryptococcus neoformans (0.9%); Candida famata (0.5%);C. lusitaniae (0.2%) and Saccharomyces cerevisiae (0.2%). Using an agar disk diffusion assay for fluconazole susceptibility it was determined that 94% of the isolates were susceptible, 5% dose-dependent susceptible and only 1% resistant. All isolates of C. albicans were susceptible (one being dose dependent sensitive) to fluconazole. The only yeasts resistant to fluconazole were: C. guillermondii (1 isolate), C. glabrata (3 isolates) and C. parapsilosis (1 isolate).

Cryptococcus neoformans: A central nervous system isolate from an AIDS patient that is rhinotropic in a normal mouse model

A strain of Cryptococcus neoformans that was isolated from the cerebrospinal fluid of a human diagnosed as having acquired immunodeficiency syndrome (AIDS), and that produced cutaneous lesions in experimentally infected, normal mice is described. Although no unusual cutaneous manifestations were noted in the patients records, this isolate of C. neoformans proved to be dermotropic when injected intravenously into CD-1 mice. The LD50 at 28 days post infection ranged from 3.6–7.5×105 cells per mouse, and in vitro growth rate studies demonstrated that this isolate grew well at 35 °C and at 37 °C, but did not grow at 40 °C and higher. This isolate was rhinotropic producing large granulomatous lesions in the nasal tissues. Other cutaneous tissues affected were the periocular tissues, ears, feet and tail, although the granulomas were nodular in structure and less necrotic than the nasal lesions. The brain, lungs, liver, kidneys and spleen also were culture positive for C. neoformans. Histopathologically, each affected tissue examined had large densities of yeast cells and a chronic, granulomatous host response. Animals surviving the infection appeared to develop a commensal-type relationship with the infective yeast. This is the first report of an isolate of C. neoformans from an AIDS patient that has caused cutaneous manifestations in an animal model. The model described in this report may be useful for elucidating pathogenic mechanisms of cryptococcosis, particularly cutaneous manifestations of the disease.

Cryptococcus neoformans in vivo protection of mice by pretreatment with pyran copolymer.

Synthetic polyanions have been shown to alter host resistance to infection. The anticryptococcal effect of pyran copolymer was assessed in vivo and in vitro. Pretreatment with pyran copolymer significantly extended mean survival in mice lethally infected with Cryptococcus neoformans when compared to untreated animals (p < 0.01). The anticryptococcal effect of peritoneal exudate cells (PEC) elicited by 10% thioglycollate or pyran copolymer (25 mg/kg) was assessed in vitro. Initial percent phagocytosis of both encapsulated and non-encapsulated isolates of C. neoformans was greatest in the pyran elicited PEC. Significant killing of C. neoformans in vitro was observed only in pyran-activated PEC cultures combined with non-encapsulated cells of C. neoformans, although pyran PEC did inhibit initial growth of phagocytized encapsulated yeast cells. The protection of pyran copolymer pretreated mice from infection with C. neoformans, but the absence of significant killing of encapsulated yeast in vitro suggest a complex mechanism of host defense which may involve an activation of the reticuloendothelial system by pyran copolymer.

Renal pathology and spleen cell chemiluminescence of mice infected with a wild-type and a low-virulence mutant of candida albicans

Pathogenicity and virulence factors were studied for a wild-type strain of Candida albicans (MY 1044) and an auxotrophic, temperature-sensitive mutant strain (MY 1049) that was derived by ultraviolet irradiation. The mutant was a temperature-sensitive, serine auxotroph. Renal pathology and chemiluminescence of spleen cells from infected mice were assessed in an attempt to identify virulence factors. Renal damage was evident following intravenous infection with either strain, although the mutant appeared to be less invasive; MY 1044 produced characteristic miliary, subcapsular lesions, while the mutant (MY 1049) produced large granulomas. Spleen cells from each infected group were stimulated in vitro with either phytohemagglutinin, concanavalin A or opsonized yeast cells to measure the respiratory burst using a luminol-dependent chemiluminescence assay. The highest chemiluminescence responses correlated with severe renal damage (uremia) and not with yeast virulence. No differences in chemiluminescence were observed among spleen cells from mice infected with either strain when renal pathology was minimal.