Famciclovir: a new systemic antiviral agent for herpesvirus infections.

Acyclovir was the first antiviral drug approved for the treatment of herpes zoster. Several new antiviral agents have since been introduced, one of which is famciclovir. The pharmacokinetics of famciclovir allow a more convenient dosing schedule than the schedule used with acyclovir. Famciclovir is metabolized in the liver, but the P450 cytochrome system is not involved. Both acyclovir and famciclovir accelerate cutaneous healing, but studies suggest that famciclovir may reduce the severity of postherpetic neuralgia when compared with placebo. Famciclovir is currently approved only for use in immunocompetent patients, but clinical trials involving immunocompromised patients are in progress.

Control of methicillin-resistant Staphylococcus aureus at a university hospital: one decade later.

OBJECTIVE: To investigate the cause of increasing rates of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection at a university hospital. DESIGN: Review of data collected by prospective hospital wide surveillance regarding rates of nosocomial MRSA colonization and infection. SETTING: A 700-bed university hospital providing primary and tertiary care. PATIENTS: Patients admitted to the hospital between 1986 and 1993 who were found to be infected or colonized with MRSA. MAIN OUTCOME MEASUREMENT: Rates of MRSA infection and colonization. RESULTS: MRSA infection or colonization was identified in 399 patients (0.18%) admitted during the 8-year study. There was no correlation between the annual rates of MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) infections (P = .66). The frequency of both nosocomial and non-nosocomial cases increased significantly over the last 4 years of the study (P < .001 for trend). The ratio of patients who had acquired MRSA nosocomially to those admitted who already were infected or colonized decreased significantly during the study period (P = .002 for trend). There was a significant increase in the frequency of patients with MRSA being transferred from nursing homes and other chronic care facilities (P = .011). A cost-benefit analysis suggested that surveillance cultures of patients transferred from other healthcare facilities would save between $20,062 and $462,067 and prevent from 8 to 41 nosocomial infections. CONCLUSIONS: An increase in the incidence of nosocomial MRSA infection was associated with an increased frequency of transfer of colonized patients from nursing homes and other hospitals. The lack of correlation between rates of MRSA and MSSA infections suggested that MRSA infections significantly increased the overall rate of staphylococcal infection. Screening cultures of transfer patients from facilities with a high prevalence of MRSA may offer significant benefit by preventing nosocomial infections and reducing patient days spent in isolation.

New macrolide antibiotics: clarithromycin and azithromycin.

Clarithromycin and azithromycin are new semisynthetic macrolide antibiotics structurally related to erythromycin. They are well absorbed and widely distributed, with excellent cellular and tissue penetration. Both have a broader spectrum of activity and fewer gastrointestinal side effects than erythromycin. Currently, clarithromycin and azithromycin are approved by the U.S. Food and Drug Administration for respiratory tract infections and skin infections, but they may also have use in mycobacterial and Toxoplasma infections in patients with acquired immunodeficiency syndrome.

Immunologic effects of nickel: I. Suppression of cellular and humoral immunity.

The effects of nickel chloride on the cellular and humoral immune responses of mice were studied. A single intramuscular injection of nickel chloride (18.3 mg/kg) caused a significant involution of the thymus within 2 days following treatment. Significant reductions in the in vitro mitogen-stimulated response of lymphocytes from nickel chloride-treated mice (24 hr following a single injection of 18.3 or 36.6 mg/kg) were observed for the T-cell mitogens phytohemagglutinin (PHA) and concanavalin A (Con A), and the B- and T-cell mitogen pokeweed mitogen (PWM) but not the B-cell mitogen lipopolysaccharide (LPS). Theta-positive but not Ig-positive spleen cells were significantly reduced in nickel-treated mice compared with controls. Significant suppression of the primary antibody response to the T-cell dependent antigen sheep red blood cells was observed following a single injection of 18.3 mg/kg NiCl2. Natural killer (NK) cell activity was significantly suppressed following a single injection of 18.3 mg/kg NiCl2. The administration of NiCl2 (18.3 mg/kg) also decreased the amount of endotoxin required to kill 50% of treated mice, although this was not statistically significant. In all cases the immunosuppressive effects of NiCl2 were found to be transient with responses returning to normal within a few days. No alteration in the response of mice immunized with the T-cell independent antigen polyvinylpyrrolidone was observed following treatment with nickel. Furthermore, the phagocytic capacity of resident peritoneal macrophages from nickel-treated mice was not significantly different from saline-injected mice. The results indicate that NiCl2 predominantly affects T-cell mediated immune responses and natural killer cells.

Assessment of immune function development in mice irradiated in utero with 2450-MHz microwaves.

Groups of time-bred pregnant mice were irradiated with 2450-MHz microwaves at an incident power density of 28 mW/cm2 for 100 min daily from day 6 to day 18 of pregnancy. The average specific absorption rate (SAR) was 16.5 W/kg. Two experiments were performed under these conditions. At 3 and 6 weeks of age the mice were assessed for development of the primary immune response to sheep erythrocytes, in vitro mitogen-stimulated lymphocyte proliferation, and natural killer (NK) cell activity. No consistent significant difference in the primary immune response, in the mitogen response, or in the NK cell activity was observed between irradiated and sham-irradiated mice.