Intravenous acyclovir to treat mucocutaneous herpes simplex virus infection after marrow transplantation: a double-blind trial

Physicochemical Characteristics of Antimicrobials and Practical Recommendations for Intravenous Administration: A Systematic Review

Most antimicrobial drugs need an intravenous (IV) administration to achieve maximum efficacy against target pathogens. IV administration is related to complications, such as tissue infiltration and thrombo-phlebitis. This systematic review aims to provide practical recommendations about diluent, pH, osmolarity, dosage, infusion rate, vesicant properties, and phlebitis rate of the most commonly used antimicrobial drugs evaluated in randomized controlled studies (RCT) till 31 March 2023. The authors searched for available IV antimicrobial drugs in RCT in PUBMED EMBASE®, EBSCO® CINAHL®, and the Cochrane Controlled Clinical trials. Drugs' chemical features were searched online, in drug data sheets, and in scientific papers, establishing that the drugs with a pH of <5 or >9, osmolarity >600 mOsm/L, high incidence of phlebitis reported in the literature, and vesicant drugs need the adoption of utmost caution during administration. We evaluated 931 papers; 232 studies were included. A total of 82 antimicrobials were identified. Regarding antibiotics, 37 reach the "caution" criterion, as well as seven antivirals, 10 antifungals, and three antiprotozoals. In this subgroup of antimicrobials, the correct vascular access device (VAD) selection is essential to avoid complications due to the administration through a peripheral vein. Knowing the physicochemical characteristics of antimicrobials is crucial to improve the patient's safety significantly, thus avoiding administration errors and local side effects.

Antiviral Agents for the Prevention and Treatment of Herpes Simplex Virus Type-1 Infection in Clinical Oncology: A Network Meta-Analysis

Cancer therapy may be complicated and compromised by viral infections, including oral herpes simplex virus (HSV) infection. This network meta-analysis aimed to identify the best antiviral agent to prevent or treat oral HSV infection in patients being treated for cancer. A search was conducted for trials published since inception until the 10th of May 2020 in MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. A network meta-analysis was performed on the data from randomized controlled trials that assessed antiviral agents for preventive or therapeutic activity vs. placebo, no treatment or any other active intervention in patients being treated for cancer. The agents were ranked according to their effectiveness in the prevention of oral HSV using surface under the cumulative ranking (SUCRA). Grading of Recommendations, Assessment, Development and Evaluations (GRADE) was used to assess the certainty of the evidence. In total, 16 articles were included. The pooled relative risk (RR) to develop oral HSV infection in the acyclovir group was 0.17 (95% CI: 0.10, 0.30), compared to 0.22 (95% CI: 0.06, 0.77) in the valacyclovir group. Acyclovir ranked highest for the prevention of oral HSV followed by valacyclovir. Subgroup analysis with different acyclovir regimens revealed that the best regimens in terms of HSV-1 prevention were 750 mg/m2 acyclovir administered intravenously followed by 1600 mg per day orally. Acyclovir (250 mg/m2 per day) administered intravenously was the least effective against the prevention of oral HSV.

A systematic review of oral herpetic viral infections in cancer patients: commonly used outcome measures and interventions

PURPOSE

To review the literature for outcome measures for oral viral infections in cancer patients. A secondary aim was to update the Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO) clinical practice guidelines for the management of oral viral infections in cancer patients.

METHODS

Databases were searched for articles published in the English language, 1981-2013. Studies that met the eligibility criteria were reviewed systematically. The data about the outcome measures were classified according to the aim of the study: prevention, treatment, or non-interventional. The results of interventional studies were compared to the 2010 MASCC/ISOO publication.

RESULTS

Multiple clinical and laboratory tests were used to measure oral viral infections, with great variability between studies. Most of the studies were about Herpes Simplex Virus (HSV). The outcome measure that was most commonly used was the presence of HSV infection diagnosed based on a combination of suggestive clinical presentation with a positive laboratory result. HSV culture was the most commonly reported laboratory outcome measure. Acyclovir and valacyclovir were consistently reported to be efficacious in the management of oral herpetic infections. No new data on the quality of life and economic aspects was found.

CONCLUSIONS

Considering the variability in outcome measures reported to assess oral herpetic infections the researcher should select carefully the appropriate measures based on the objective of the study. Acyclovir and valacyclovir are effective in the management of oral herpetic infections in patients receiving treatment for cancer. Studies on newer anti-viral drugs may be useful to address the issue of anti-viral resistance.

Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016

Infectious complications after allogeneic haematopoietic stem cell transplantation (allo-HCT) remain a clinical challenge. This is a guideline provided by the AGIHO (Infectious Diseases Working Group) of the DGHO (German Society for Hematology and Medical Oncology). A core group of experts prepared a preliminary guideline, which was discussed, reviewed, and approved by the entire working group. The guideline provides clinical recommendations for the preventive management including prophylactic treatment of viral, bacterial, parasitic, and fungal diseases. The guideline focuses on antimicrobial agents but includes recommendations on the use of vaccinations. This is the updated version of the AGHIO guideline in the field of allogeneic haematopoietic stem cell transplantation utilizing methods according to evidence-based medicine criteria.

The Influence of Cyclosporin Immunosuppression on the Efficacy of Famciclovir or Valaciclovir Chemotherapy Studied in a Murine Herpes Simplex Virus Type 1 Infection Model

Mice with or without immunosuppression by cyclosporin (Cy) were inoculated with herpes simplex virus type 1 in the ear pinna. Without immunosuppression, 20% of the mice died; clinical signs resolved in survivors and infectious virus was cleared by 7 to 10 days post-inoculation (p.i.). With Cy, mortality was 50%, clinical signs increased and infectious virus persisted. Mice were treated with either valaciclovir (VACV) or famciclovir (FCV) from days 1–5 or 5–10 p.i. and both compounds moderated the disease, but only FCV led to rapid restoration of body weight and complete protection from mortality. Resolution of clinical signs was more marked with immunosuppression. On cessation of VACV therapy, infectious virus recurred on individual days. Without immunosuppression, recurrence was detected in neural tissues only, but with Cy, infectious virus also recurred in skin. No recurrences of infectious virus were observed in any FCV-treated mice.

Herpes Simplex Virus Isolates from an Immunocompromised Patient who Failed to Respond to Acyclovir Treatment Express Thymidine Kinase with Altered Substrate Specificity

Ten sequential post-treatment herpes simplex virus type 1 (HSV-1) isolates were obtained from an immunocompromised patient whose infection, during prolonged treatment, became unresponsive to acyclovir (ACV). Of the ten isolates, eight later isolates were resistant in vitro to ACV and ganciclovir (DHPG), but remained sensitive to 9-β-D-arabinofuranosyladenine (ara-A) and phosphonoformate (PFA). Biochemical characterization of plaque-purified clones of the resistant isolates revealed an altered thymidine kinase (TK) substrate specificity phenotype. The comparative nucleotide sequence analysis of polymerase chain reaction (PCR)-amplified DNA encoding the TK genes of one sensitive and two resistant clones showed a single mutation at nucleotide 527. This change would result in a substitution of arginine by glutamine at residue 176 of the polypeptide, a mutation previously observed in a laboratory isolated variant, SC16 Tr7 (Darby et al., 1986).

Advances in the management of viral infections

Viral infections are common in cancer patients. The risk and severity of infection are influenced by patient, disease, treatment, and viral factors. Severe viral infections are more likely to occur in treatment regimens that are more immunosuppressive. Historically, the most frequent severe infections have been due to herpesviruses, but more recently, other pathogens, especially community respiratory and hepatitis viruses, have received increasing attention as major viral pathogens in cancer patients. Because of the new diagnostic assays and the introduction of better therapeutic options, knowledge of viral infections is important in optimizing antineoplastic therapies.

Expression of herpes simplex virus type 1 recombinant thymidine kinase and its application to a rapid antiviral sensitivity assay

Antiviral-resistant herpesvirus infection has become a great concern for immunocompromised patients. Herpes simplex virus type 1 (HSV-1) infections are treated with viral thymidine kinase (vTK)-associated drugs such as acyclovir (ACV), and most ACV-resistance (ACV(r)) is due to mutations in the vTK. The standard drug sensitivity test is usually carried out by the plaque reduction assay-based method, which requires over 10 days. To shorten the time required, a novel system was developed by the concept, in which 293T cells transiently expressing recombinant vTK derived from the test sample by transfection of the cells with an expression vector were infected with vTK-deficient and ACV(r) HSV-1 (TAR), and then cultured in a maintenance medium with or without designated concentrations of ACV, ganciclovir (GCV) and brivudine (BVdU). The replication of TAR was strongly inhibited by ACV, GCV and BVdU in 293T cells expressing recombinant vTK of the ACV-sensitive HSV-1, whereas replication was not or slightly inhibited in cells expressing the recombinant vTK of highly resistant or intermediately resistant HSV-1, respectively. An inverse correlation was demonstrated in the 50% effective concentrations (EC(50)s) and inhibitory effects of these compounds on the replication of TAR among ACV(s) and ACV(r) HSV-1 clones. These results indicate that the EC(50)s of the vTK-associated drugs including ACV can be assumed by measuring the inhibitory effect of drugs in 293T cells expressing recombinant vTK of the target virus. The newly developed antiviral sensitivity assay system for HSV-1 makes it possible to estimate EC(50) for vTK-associated drugs, when whole vTK gene is available for use by gene amplification directly from lesion's samples or from virus isolates.

A systematic review of viral infections associated with oral involvement in cancer patients: a spotlight on Herpesviridea

PURPOSE

Our aim was to evaluate the literature for the prevalence of and interventions for oral viral infections and, based on scientific evidence, point to effective treatment protocols. Quality of life (QOL) and economic impact were assessed if available in the articles reviewed.

METHODS

Our search of the English literature focused on oral viral infections in cancer patients within the timeframe of 1989-2007. Review methods were standardized. Cohort studies were used to determine the weighted prevalence of oral viral infection in cancer patients. The quality of selected articles were assessed and scored with respect to sources of bias, representativeness, scale validity, and sample size. Interventional studies were utilized to determine management guidelines. Literature search included measures of QOL and economic variables.

RESULTS

Prevalence of oral herpes simplex virus (HSV) infection in neutropenic patients was higher than in patients treated with radiotherapy for head and neck cancer (49.8% vs. 0%, respectively). In patients treated with radiochemotherapy for head and neck cancer, the prevalence of oral HSV infection increases up to 43.2% (CI, 0-100%). Prevalence of HSV infection was higher when oral ulcers existed. Information about other oral viral infections is sparse. There was a significant benefit of using acyclovir to prevent HSV oral infection (at 800 mg/day). Various dosing protocols of valacyclovir achieved prevention of HSV reactivation (500 or 1,000 mg/day). The prevalence of HSV reactivation was similar for acyclovir and valacyclovir. No information about impact on QOL and economic burden was available.

CONCLUSIONS

Acyclovir and valacyclovir are equally effective in preventing oral HSV infection. Neutropenic patients, who were primarily treated for hematological malignancies in the studies reviewed, are at a greater risk for viral infection.

A randomized, double-blind, placebo-controlled trial of valacyclovir prophylaxis to prevent zoster recurrence from months 4 to 24 after BMT

Reactivation of latent VZV remains a significant cause of morbidity after SCT. Twenty-five percent or more of patients undergoing SCT will experience zoster within the first year after transplant. Short-course (<1 year) prophylaxis with acyclovir has been shown to be effective, but compliance with five times daily dosing may be problematic. We conducted a randomized, double-blind, placebo-controlled trial of valacyclovir (VACV) 1000 mg twice daily from 4 through 24 months after SCT for the prevention of VZV. Fifty-three VZV-seropositive transplant recipients (17 auto-SCT, 36 allo-SCT) were randomized at a median of 163 days after SCT. In a modified intent-to-treat analysis of 49 patients who took study drug, 0 of 22 in the VACV arm experienced zoster reactivation, compared with 6 of 26 (23%) in the placebo arm (P=0.025). Thirty-two subjects completed therapy through the second year post transplant or first episode of zoster. Adverse events resulting in discontinuation were more frequent in the placebo group (5 of 26 vs 3 of 27 for placebo and study drug, respectively). VACV at a dose of 1000 mg twice daily through 24 months after transplant is well tolerated and effective in suppressing shingles after SCT.

Acyclovir delivery systems

Herpes viruses (herpes simplex, varicella zoster, cytomegalovirus) are the main cause of a wide variety of human infections. Although the development of successful antiviral agents against infections caused by herpes viruses had been slow until the last decade, the production of delivery systems for acyclovir are a promising alternative. The present review summarizes the principal advances made in developing carriers for the delivery of acyclovir by different routes of administration.

Interventions for the prevention and treatment of herpes simplex virus in patients being treated for cancer

BACKGROUND

Treatment of cancer is increasingly effective, but associated with oral complications such as mucositis, fungal infections, bacterial infections and viral infections such as the herpes simplex virus (HSV).

OBJECTIVES

To examine the effects of interventions for the prevention or treatment or both, of herpes simplex virus in patients receiving treatment for cancer.

SEARCH STRATEGY

We searched the following databases: Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE, EMBASE, CINAHL, CANCERLIT, SIGLE and LILACS. The reference list of all related review articles and articles considered to be potentially relevant were checked for further trials. Authors of identified trials and known specialists in the field were also contacted in an attempt to identify any additional published or unpublished trials. Date of most recent search: November 2008.

SELECTION CRITERIA

All randomised controlled trials comparing interventions for the prevention or treatment or both of HSV infection in people being treated for cancer. Outcomes were presence/absence of clinical/culture positive HSV infections (prevention), time to complete healing of lesions (treatment), duration of viral shedding, recurrence of lesions, relief of pain, amount of analgesia, duration of hospital stay, cost of oral care, patient quality of life and adverse effects.

DATA COLLECTION AND ANALYSIS

Data were independently extracted, in duplicate, by two review authors. Authors were contacted for details of randomisation, blindness and sample demographics where necessary. Quality assessment was carried out on randomisation, blindness, withdrawals and selective reporting. The Cochrane Collaboration's statistical guidelines were followed and risk ratio (RR) values were calculated using random-effects models.

MAIN RESULTS

Seventeen trials satisfied the inclusion criteria. Four trials evaluated preventative interventions for HSV lesions, three trials for viral isolates, and eight trials evaluated both outcome measures. A single trial reported on the cost of prophylaxis for HSV. Two trials evaluating treatment reported on time to healing, duration of viral shedding and relief of pain. No trials reported on duration of hospital stay, amount of analgesia or patient quality of life.In placebo controlled trials, aciclovir was found to be effective for the prevention of HSV infections as measured by oral lesions or viral isolates (RR = 0.16, 95% confidence interval (CI) 0.08 to 0.31 nine trials; RR = 0.17, 95% CI 0.07 to 0.37 nine trials). There is no evidence that valaciclovir is more efficacious than aciclovir, or that higher doses of valaciclovir are more effective than lower doses. Placebo was found to be more effective than prostaglandin E for prevention of viral isolates (RR = 1.87, 95% CI 1.12 to 3.14 one trial).Aciclovir was also found to be effective for the treatment of HSV in terms of duration of viral shedding (median of 2.5 days versus 17.0 days, P = 0.0002; 2 days compared to more than 9, P = 0.0008), time to first decrease in pain (median 3 days compared to 16, P = 0.04), complete resolution of pain (9.9 days compared to 13.6 days, P = 0.01; median of 6 days compared to 16, P = 0.05), 50% healing (median of 6 days compared to 11, P = 0.01) and total healing (median 13.9 days compared to 20.7 days, P = 0.08; median of 8 days compared to 21, P = 0.0).

AUTHORS' CONCLUSIONS

There is evidence that aciclovir is efficacious in the prevention and treatment of herpes simplex virus infections. There is no evidence that valaciclovir is more efficacious than aciclovir, or that a high dose of valaciclovir is better than a low dose of valaciclovir. There is evidence that as a prophylaxis, placebo is more efficacious than prostaglandin E. However, in all included trials, risk of bias is unclear.

Management of HSV, VZV and EBV infections in patients with hematological malignancies and after SCT: guidelines from the Second European Conference on Infections in Leukemia

These guidelines on the management of HSV, VZV and EBV infection in patients with hematological malignancies and after SCT were prepared by the European Conference on Infections in Leukemia following a predefined methodology. A PubMed search was conducted using the appropriate key words to identify studies pertinent to management of HSV, VZV and EBV infections. References of relevant articles and abstracts from recent hematology and SCT scientific meetings were also reviewed. Prospective and retrospective studies identified from the data sources were evaluated, and all data deemed relevant were included in this analysis. The clinical and scientific background was described and discussed, and the quality of evidence and level of recommendation were graded according to the Centers for Disease Control criteria.

Chapter 3 Antiviral drugs: general considerations

The development of an antiviral drug as well as of other drugs is a long process. In most programmes the screening and evaluation start using inhibition of virus multiplication in cell cultures, but in some instances the screening starts in animal models of different viral diseases. In these cases, the mechanism of action has to be analyzed after the in vivo effect has been found. It is not possible to specify precisely the time and resources required in a newly started project to find a compound active against a virus infection but 5-10 years is a reasonable estimation. For some viruses such as herpesviruses, where a number of active inhibitors are already known, the task is simpler than it is to find inhibitors of a virus such as influenza against which only a few active inhibitors have been reported. Evaluation of clinical efficacy in humans is a large and difficult part of the development of an antiviral drug. The number of uncontrolled clinical studies claiming efficacy of different drugs against viral diseases is depressingly large. It is essential to perform double-blind, placebo-controlled and statistically well evaluated studies to be able to judge the clinical efficacy of an antiviral drug. As the knowledge of the detailed natural history and molecular biology of viral diseases and viruses themselves increases, one will obviously have better opportunities to find new drugs. Methods such as X-ray diffraction measurement and NMR determinations will probably lead to a detailed understanding of the structures and interactions taking place at the active site of viral enzymes and their cellular counterparts.

Design and development of multivesicular liposomal depot delivery system for controlled systemic delivery of acyclovir sodium

The aim of the present study was to design a depot delivery system of acyclovir sodium using multivesicular liposomes (MVLs) to overcome the limitations of conventional therapies and to investigate its in vivo effectiveness for sustained delivery. MVLs of acyclovir were prepared by the reverse phase evaporation method. The loading efficiency of the MVLs (45%-82%) was found to be 3 to 6 times higher than conventional multilamellar vesicles (MLVs). The in vitro release of acyclovir from MVL formulations was found to be in a sustained manner and only 70% of drug was released in 96 hours, whereas conventional MLVs released 80% of drug in 16 hours. Following intradermal administration to Wistar rats, the MVL formulations showed effective plasma concentration for 48 hours compared with MLVs and free drug solution (12-16 hours). C(max) values of MVL formulations were significantly less (8.6-11.4 microg/mL) than MLV and free drug solution (12.5 microg/mL). The AUC(0-48) of the MVL formulations was 1.5- and 3-fold higher compared with conventional liposomes and free drug solution, respectively. Overall, formulations containing phosphatidyl glycerol as negatively charged lipid showed better results. The MVL delivery system as an intradermal depot offers the advantage of a very high loading and controlled release of acyclovir for an extended period of time. The increase in AUC and decrease in C(max) reflects that the MVL formulations could reduce the toxic complications and limitations of conventional iv and oral therapies.

Plasmacytoid dendritic cell reconstitution following bone marrow transplantation: subnormal recovery and functional deficit of IFN-alpha/beta production in response to herpes simplex virus

Infections with herpesviruses were frequent after bone marrow transplantation (BMT) before the preventive use of antiviral drugs, suggesting a deficit of innate immunity. A retrospective phenotypical and functional study was carried out on 25 patients 1-36 months after allogeneic BMT. Leukocyte counts followed a normal reconstitution, including natural killer (NK) cells and monocytes. Plasmacytoid dendritic cell (PDC) counts increased steadily, although they remained below normal values after 2 years. Most patients produced less interferon- alpha/beta (IFN-alphabeta) in vitro than healthy controls after infection with herpes simplex virus type 1 (HSV-1), whereas they responded normally to Sendai virus (SV). In addition, 6 patients had biologic signs of infection with herpesviruses, confirming a specific immunologic deficit against these viruses. IFN production was not correlated to PDC counts or to the occurrence of graft-versus-host disease (GVHD). Because all patients were under immunosuppressive treatment, we investigated the effect of drugs on IFN production by mononuclear cells. Glucocorticoids and cyclosporine A inhibited IFN production by infected leukocytes, with a predominant action on HSV-1-infected PDC. The inability of transplanted patients to mount an efficient immune response to herpesviruses may be partly related to drug toxicity toward cells of the innate immune system.

Antiviral therapies in children: has their time arrived?

The increase in the number and classes of antiviral agents that has occurred since the 1980s is remarkable. The rapid expansion in therapeutic options for previously untreatable illnesses challenges clinicians to gain familiarity and experience with these new drugs, especially with regard to their use in children. This article describes the clinical utilities, pharmacokinetics, and adverse effects of these new drugs to empower practitioners to use them appropriately.

National Seroprevalence and Trends in Herpes Simplex Virus Type 1 in the United States, 1976–1994

OBJECTIVES

The objectives of this study were to estimate national seroprevalence of herpes simplex virus type 1 (HSV-1), describe trends in seroprevalence, and examine correlates of infection.

GOAL

The goal of this study was to measure the burden of HSV-1 infection in the U.S. population.

STUDY

We tested serum samples for HSV-1 antibody and analyzed questionnaire data collected for the second and third National Health and Nutrition Surveys (NHANES II, 1976-80; NHANES III, 1988-94). Seroprevalence estimates were weighted to represent the total U.S. population.

RESULTS

At the time of NHANES III, two thirds (68%) of the U.S. population 12 years and older had HSV-1 antibody. Prevalence increased with age and varied by race/ethnicity; the majority of persons in all race/ethnic groups were HSV-1-seropositive by age 30. Overall, the national seroprevalence of HSV-1 decreased nonsignificantly by 2% in the years between NHANES II and III; decreases in HSV-1 seroprevalence in some population subgroups were balanced by increases in other groups.

CONCLUSIONS

There was no overall change in the seroprevalence of HSV-1 in the U.S. population between NHANES II and III.

Toxic effects of bis(thiosemicarbazone) compounds and its palladium(II) complexes on herpes simplex virus growth

Here, we present data on the activity of benzyl bis(thiosemicarbazone); 3,5-diacyl-1,2,4-triazole bis(4-methylthiosemicarbazone) and their Pd(II) complexes against the replication of wild type and of acyclovir (ACV)-resistant, herpes simplex virus type 1 (HSV 1) and type 2 (HSV 2) strains. The data were compared to those under the action of acyclovir. The testing of cytotoxic activity suggests that these compounds may be endowed with important antiviral properties. It is interesting to note that the Pd(II)-benzyl bis(thiosemicarbazone) complex, 2, exhibits a significant activity against acyclovir-resistant viruses R-100 (HSV 1) and PU (HSV 2) with an in vitro selectivity index (SI) of 8.0 vs. 0.01 for acyclovir. This complex also negatively influenced the expression of key structural HSV 1 proteins (VP23, gH and gG/gD), thus suppressing simultaneously virus entry, transactivation of virus genome, capsid assembly, and cell-to-cell spread of infectious HSV progeny.

Phenotypic and genotypic characterization of clinical isolates of herpes simplex virus resistant to aciclovir

A panel of 10 clinical isolates of herpes simplex virus (HSV) deficient in the expression of thymidine kinase (TK) and phenotypically resistant to aciclovir was characterized. Sequence analysis revealed a variety of mutations in TK (nucleotide substitutions, insertions and deletions), most of which resulted in truncated TK polypeptides. In line with previous reports, the most common mutation was a single G insertion in the 'G-string' motif. One HSV-1 isolate and two HSV-2 isolates appeared to encode full-length polypeptides and, in each case, an amino acid substitution likely to be responsible for the phenotype was identified. Pathogenicity was determined using a zosteriform model of HSV infection in BALB/c mice. The majority of isolates appeared to show impaired growth at the inoculation site compared with wild-type virus. They also showed poor replication in the peripheral nervous system and little evidence of zosteriform spread. One exception was isolate 4, which had a double G insertion in the G-string but, nevertheless, exhibited zosteriform spread. These studies confirmed that TK-deficient viruses display a range of neurovirulence with respect to latency and zosteriform spread. These results are discussed in the light of previous experience with TK-deficient viruses.

Characterization of a neurovirulent aciclovir-resistant variant of herpes simplex virus

A clinical isolate of herpes simplex virus type 1 that is aciclovir resistant but neurovirulent in mice was described previously. The mutation in this virus is a double G insertion in a run of seven G residues that has been shown previously to be a mutational hotspot. Using a sensitive assay, it has been demonstrated that preparations of this virus are able to induce low but consistent levels of thymidine kinase (TK) activity. However, this activity results from a high frequency mutational event that inserts a further G into the 'G-string' motif and thus restores the TK open reading frame. Passage of this virus through the nervous system of mice results in the rapid selection of the TK-positive variant. Thus, this variant is the major component in virus reactivated from latently infected ganglia. Mutation frequency appears to be influenced by the genetic background of the virus.

The pediatrician and medical care of the child with cancer

The child's pediatrician is an important resource for families regarding a host of issues such as infections, complications and side effects of chemotherapy, school issues, and psychosocial stressors that are common in families of children with life-threatening illness. This article provides guidance for caring for children with malignancies in the primary care setting.

Antiviral agents: Nonantiviral drugs

The current arsenal of antiviral agents available to the practitioner is expanding rapidly, such that by the time this article goes to press, new drugs may have already been added. Although the majority of approved drugs have been developed for use in only a few viral infections (eg, HIV, herpesviruses, and papillomavirus), discoveries made in the development of these drugs may lead to antiviral agents effective against other viruses. In addition, new uses for the currently available drugs are under evaluation. This review of antiviral agents discusses the treatments available for viral infections such as herpes simplex virus, varicella zoster virus, cytomegalovirus, human papillomavirus, chronic viral hepatitis, and others.

Herpes simplex virus type 1 variants arising after selection with an antiviral carrageenan: lack of correlation between drug susceptibility and syn phenotype

Natural carrageenans of diverse structural types isolated from the red seaweed Gigartina skottsbergii were recently identified as potent and selective inhibitors of herpes simplex virus types 1 and 2 (HSV-1 and -2). The mu/nu-carrageenan 1C3 was tested in vitro for its ability to select resistant variants. After serial passages of HSV-1 strain F in Vero cells in the presence of increasing concentrations of 1C3, viruses emerged that were approximately 2- to 10-fold more resistant to 1C3 inhibition than parental virus; these viruses formed large plaques with an altered syncytial phenotype (1C3-syn). Plaque-purified syncytial variants isolated from passages 13 and 14 have shown variable levels of resistance to 1C3, as well as to the other antiviral carrageenans isolated from G. skottsbergii and to other sulfated polysaccharides with known antiviral activity, such as heparin and dextran sulfate 8000, but all the clones were susceptible to acyclovir. The syn phenotype was not related to polysaccharide resistance. All the 1C3-syn variants formed large syncytia in Vero and CV-1 cells but did not induce fusion in other cell types. The growth efficiency in Vero cells, as well as the virulence for mice by intracerebral or intraperitoneal inoculation of 1C3-syn variants, showed no significant alterations in comparison with the parental virus. The syncytial properties were not affected by cyclosporine or melittin, suggesting that an alteration on glycoprotein gB could be responsible for the syn phenotype induced by 1C3.

Penciclovir susceptibilities of herpes simplex virus isolates from patients using penciclovir cream for treatment of recurrent herpes labialis

The antiherpesvirus agent penciclovir (PCV) shares an identical activation pathway and a similar mode of action with acyclovir (ACV). However, since PCV represents a relatively recent treatment option, the clinical resistance profile to PCV is less well known. A susceptibility program was established to assess the resistance profile for serial herpes simplex virus isolates from immunocompetent patients with recurrent herpes labialis obtained throughout a 4-day period of treatment with topical PCV (1% cream) or a placebo. Two isolates (2 of 1,035 [0.19%]), representing 0.34% of the patients (2 of 585), were confirmed to be PCV-resistant (Pcv(r)) herpes simplex virus type 1 by a plaque reduction assay in MRC-5 cells. These two viruses were highly resistant to PCV (50% inhibitory concentrations [IC(50)s], >55 micro g/ml) and were isolated less than 17 h after the start of patient-initiated treatment. However, subsequent isolates on days 2 and 3 from these patients were completely susceptible to PCV (IC(50)s, <2.0 micro g/ml). Thus, it is not clear whether the resistance to PCV for these two early-treatment isolates was directly associated with the 17 h of PCV treatment; several possible explanations are discussed. In an analysis of the distribution of IC(50) differences between the first and last isolates, there were three patients with minor IC(50) increases in the PCV-treated population and one in the placebo-treated group, although statistically, only the latter was an outlier. No patients were found to have Pcv(r) virus at the end of acute treatment, regardless of treatment group. Overall, the prevalence of Pcv(r) was found to be similar to the 0.3% Acv(r) reported for immunocompetent, untreated populations.

Resistance of herpesviruses to antiviral drugs: clinical impacts and molecular mechanisms

Nucleoside analogues such as acyclovir and ganciclovir have been the mainstay of therapy for alphaherpesviruses (herpes simplex virus (HSV) and varicella-zoster virus (VZV)) and cytomegalovirus (CMV) infections, respectively. Drug-resistant herpesviruses are found relatively frequently in the clinic, almost exclusively among severely immunocompromised patients receiving prolonged antiviral therapy. For instance, close to 10% of patients with AIDS receiving intravenous ganciclovir for 3 months excrete a drug-resistant CMV isolate in their blood or urine and this percentage increases with cumulative drug exposure. Many studies have reported that at least some of the drug-resistant herpesviruses retain their pathogenicity and can be associated with progressive or relapsing disease. Viral mutations conferring resistance to nucleoside analogues have been found in either the drug activating/phosphorylating genes (HSV or VZV thymidine kinase, CMV UL97 kinase) and/or in conserved regions of the viral DNA polymerase. Currently available second line agents for the treatment of herpesvirus infections--the pyrophosphate analogue foscarnet and the acyclic nucleoside phosphonate derivative cidofovir--also inhibit the viral DNA polymerase but are not dependent on prior viral-specific activation. Hence, viral DNA polymerase mutations may lead to a variety of drug resistance patterns which are not totally predictable at the moment due to insufficient information on specific drug binding sites on the polymerase. Although some CMV and HSV DNA polymerase mutants have been found to replicate less efficiently in cell cultures, further research is needed to correlate viral fitness and clinical outcome.

Summary of the Guidelines for Preventing Opportunistic Infections among Hematopoietic Stem Cell Transplant Recipients

This article contains highlights of "Guidelines for Preventing Opportunistic Infections among Hematopoietic Stem Cell Transplant Recipients: Recommendations of the CDC, the Infectious Diseases Society of America, and the American Society of Blood and Marrow Transplantation," which was published in the Morbidity and Mortality Weekly Report. There are sections on the prevention of bacterial, viral, fungal, protozoal, and helminth infections and on hospital infection control, strategies for safe living following transplantation, immunizations, and hematopoietic stem cell safety. The guidelines are evidence-based, and prevention strategies are rated by both the strength of the recommendation and the quality of evidence that supports it. Recommendations are given for preventing cytomegalovirus disease with prophylactic or preemptive gancyclovir, herpes simplex virus disease with prophylactic acyclovir, candidiasis with fluconazole, and Pneumocystis carinii pneumonia with trimethoprim-sulfamethoxazole. Hopefully, following the recommendations made in the guidelines will reduce morbidity and mortality from opportunistic infections in hematopoietic stem cell transplant recipients.

Antiviral agents

The potential severity of many viral infections and the lack of appropriate treatment for these diseases have been a source of endless frustration and helplessness for clinicians. The newly developed field of antiviral therapy is expanding at an astounding rate, with new discoveries each day. Although physicians are not yet able to cure many of the viral infections, such as HSV, HIV, and CMV, a means of controlling them is available. It is hoped that the research and investigations currently under way will lead to a future era of antiviral drugs that will be able to eradicate these diseases.

A risk-benefit evaluation of aciclovir for the treatment and prophylaxis of herpes simplex virus infections

The objective of this article is to review and evaluate risks and benefits associated with the use of acyclovir in the treatment and prophylaxis of common manifestations of herpes simplex virus (HSV) infections in immunocompetent and immunocompromised patients. Information was found through a MEDLINE search using keywords: herpes simplex virus, genital herpes, herpes labialis, acyclovir and acyclovir. Selected articles were randomised, double-blind, placebo-controlled, clinical trials. 30 such trials involving 3364 persons were evaluated. All articles were reviewed by the authors and the data were extracted and summarised. In both immunocompetent and immunocompromised hosts, acyclovir therapy demonstrated a high degree of clinical efficacy. None of the studies reported statistically significant differences between acyclovir and placebo for mild or major adverse events. This evaluation found that acyclovir is both effective and well tolerated for treatment and prophylaxis of genital, oral and mucocutaneous HSV infections in immunocompetent and immunocompromised patients. In most clinical scenarios. the benefit of acyclovir exceeded any risks by a comfortable margin. The availability of acyclovir as a generic preparation further improves the benefit to cost ratio.

Intravenous penciclovir for treatment of herpes simplex infections in immunocompromised patients: results of a multicenter, acyclovir-controlled trial. The Penciclovir Immunocompromised Study Group

The efficacy and safety of penciclovir (PCV) for the treatment of herpes simplex virus (HSV) infections in immunocompromised (IC) patients were studied in a double-blind, acyclovir (ACV)-controlled, multicenter study. A total of 342 patients with mucocutaneous HSV infections received 5 mg of PCV per kg every 12 or 8 h (q12h or q8h) or 5 mg of ACV per kg q8h, beginning within 72 h of lesion onset and continuing for up to 7 days. The mean age of the patients was 49 years; 94% were white and 52% were female. The main reasons for their IC states were hematologic disorder (63%) and transplant plus hematologic disorder (16%). Clinical and virological assessments were performed daily during the 7-day treatment and then every other day until lesion healing. The primary efficacy parameter addressed new lesion formation. Secondary end points focused on viral shedding, healing, and pain. Approximately 20% of patients in each treatment group developed new lesions during therapy; thus, equivalence with ACV (defined prospectively) was demonstrated for both q12h and q8h PCV regimens. For all three treatment groups, the median time to the cessation of viral shedding was 4 days and the median time to complete healing was 8 days; there were no statistically significant differences in the rates of complete healing or the cessation of viral shedding when the results for PCV q12h and q8h were compared with those for ACV q8h. In addition, there was no statistically significant difference between PCV q12h or q8h, compared with ACV q8h, for the resolution of pain. PCV was well tolerated, with an adverse event profile comparable to that of ACV. In conclusion, PCV q12h is a well-tolerated and effective therapy for mucocutaneous HSV infection in IC patients and offers a reduced frequency of dosing compared with ACV q8h.

Survey of resistance of herpes simplex virus to acyclovir in northwest England

Acyclovir (ACV) has been used for more than 15 years in the management of herpes simplex virus (HSV) and varicella-zoster virus (VZV) disease. The present survey was undertaken to assess the level of ACV resistance in the population. More than 2,000 HSV isolates from both immunocompetent and immunocompromised patients in northwest England were collected over a 2-year period and tested for sensitivity to ACV. These studies suggested a prevalence of resistance of approximately 0.1 to 0.6% in immunocompetent individuals, with no apparent difference in prevalence between treated and untreated groups. In line with previous studies, the prevalence of resistance in treated immunocompromised individuals was approximately 6%.

Varicella pneumonitis: clinical presentation and experience with acyclovir treatment in immunocompetent adults

OBJECTIVE

Cases of varicella pneumonitis were reviewed to examine the effects of acyclovir therapy on outcome.

METHODS

A retrospective chart review was done of all admissions of adults to two hospitals, between 1985 and 1995, because of complications of chickenpox.

RESULTS

Fifteen patients were hospitalized for varicella pneumonitis during this period. No patient had a history of chickenpox as a child; all had a recent history (within 2-4 weeks prior to admission) of exposure to chickenpox in their family or neighborhood and developed respiratory symptoms 1 to 4 days after the appearance of the rash. Twelve patients (80%) had a history of cigarette smoking, and seven patients had a platelet count below the normal range. All patients were treated with intravenous acyclovir within 24 hours of admission, and all but one survived and were discharged from the hospital without comorbid conditions. The one mortality was attributed to bacterial superinfection.

CONCLUSIONS

Acyclovir treatment may be of benefit for varicella pneumonitis, but no controlled trial has been performed to definitively answer this question.

Oral lesions in organ transplant patients

Patients who have undergone organ transplantation can present with a variety of oral lesions that appear to be related either directly to their medication or arise as a consequence of drug-induced immunosuppression. Such lesions include hairy leukoplakia, an increased propensity to both fungal and viral infections and a high incidence of malignant change, especially lip cancer. Cyclosporin remains the immunosuppressant of choice in most transplant patients. Gingival overgrowth is the main unwanted oral effect associated with cyclosporin. Some 30% of dentate transplant experience this problem, which is further compounded by concomitant medication with a calcium channel blocker. This review appraises the various oral problems that can arise in this group of patients and emphasises the importance of regular oral screening and the establishment of links with the various transplant teams.

Herpes Simplex Infections in the Critical Care Setting

Infections caused by herpes simplex virus (HSV) types 1 and 2 are widely prevalent and usually asymptomatic. In the immunocompromised or severely ill patient, however, HSV can cause a variety of mucosal and systemic syndromes. Organ systems most susceptible include the gastrointestinal tract, lungs, and the central nervous system. Systemic disseminated disease may also occur. With the exception of herpes encephalitis, clinical diagnosis of serious HSV infections is difficult, because it occurs in hosts who are susceptible to a wide range of infectious and metabolic problems. We review the presenting syndromes of HSV infection in the critically ill patient, and outline current concepts for diagnosis and treatment.

Management of genital herpes

Oral acyclovir is the therapy of choice for treatment of first-episode genital herpes, for suppression of frequently recurrent genital herpes, and, in selected patients, for episodic treatment of recurrent genital herpes. Topical acyclovir therapy is relatively or totally ineffective and is therefore discouraged. Indications for intravenous acyclovir therapy of mucocutaneous HSV infections include patients hospitalized with severe first-episode genital herpes and immunocompromised patients who have severe infections or who cannot swallow the oral preparation. The most promising investigational drugs are the oral prodrugs valaciclovir and famciclovir. Famciclovir is licensed in the U.S. for treatment of zoster but not for treatment of mucocutaneous genital herpes. When used for episodic therapy of recurrent genital herpes, both famciclovir and valaciclovir effectively reduce the duration of viral shedding, lesion healing times, and the duration of symptoms. Suppressive therapy with famciclovir has also been shown to be effective in reducing the frequency of episodes in women with frequently recurring genital herpes. Although these drugs can be given less frequently than oral acyclovir, there is yet no clear indication that they are more effective or better tolerated than oral acyclovir.

Viral infections in severely immunocompromised cancer patients

Immunocompromised cancer patients are susceptible to infection by many viral pathogens. The most serious morbidity results from active infection by members of the herpes virus family. Reactivation of latent virus occurs as a sequela of cytotoxic therapy and deficiency of cell-mediated immunity, especially cytotoxic responses, the major host protective defense. Herpes simplex virus and varicella zoster virus infections are problematic in patients with all types of cancer; cytomegalovirus infections cause life-threatening morbidity in bone marrow transplant patients. Several antiviral agents are highly active against these pathogens and different strategies of using them have resulted in reduced morbidity and mortality. Ultimately, the resolution of these infections is dependent on the control of the malignancy and the ability of the patient to mount an adequate immune response.

Infections in cancer patients: some controversial issues

Despite more than two decades of clinical research into the management of infections in the neutropenic cancer patient, many patients still develop serious morbidity from infection and all too many still die. A number of controversies surround (a) the use of combination versus monotherapy for initial empiric administration; (b) the use of vancomycin as part of the initial regimen; (c) the origin of Staphylococcus epidermidis infections (i.e., mostly from vascular catheters or mostly from the alimentary canal); (d) the use of acyclovir for herpes simplex prophylaxis during remission induction for acute leukemia patients not undergoing bone marrow transplantation; (e) the use of alimentary canal microbial suppression or reverse isolation in a room with laminar air flow, or both, as infection prevention techniques. Current recommendations and observations include the following. (a) Monotherapy with ceftazidime or imipenem is effective and appropriate for patients with moderate granulocytopenia at limited risk for infection with a resistant organism. Combination therapy is recommended for patients with profound, persistent granulocytopenia who are at high risk for gram-negative bacteremia; such bacteremic patients have a better prognosis with combined-modality therapy. (b) Vancomycin need not be included in the initial regimen although some centers may choose to do so because of the high prevalence of gram-positive bacteremias. (c) Despite the ubiquitous presence of indwelling vascular catheters, most S. epidermidis infections among neutropenic patients originate from along the alimentary canal. (d) Herpes simplex infection is much more common following standard remission induction chemotherapy than previously recognized. Acyclovir will reduce these infections and concurrently probably reduce the likelihood of resultant bacterial/fungal co-infections and superinfections. (e) Selective microbial suppression is appropriate for patients expected to experience prolonged (more than 2 weeks) or profound (below 100 granulocytes/microliters) granulocytopenia. Agents chosen should suppress aerobic but not anaerobic flora (maintain colonization resistance) and need to have an effect on both the oral cavity and esophagus as well as the intestines.

Role of upper endoscopy in evaluation of upper gastrointestinal symptoms in patients undergoing bone marrow transplantation

We reviewed our upper endoscopy (esophagogastroduodenoscopy, EGD) experience in a group of 65 consecutive patients receiving carmustine (BCNU) 600 mg/m2, cisplatin 200 mg/m2, VP-16 2400 mg/m2, and autologous bone marrow transplantation (BMT) for relapsed or refractory non-Hodgkin's lymphoma or Hodgkin's disease. Forty-one patients (33 with chest irradiation) underwent 48 EGDs for the following symptoms: upper gastrointestinal bleeding (melena and/or hematemesis) (12/48); persistent nausea and vomiting (7/48); odynophagia (25/48); and dysphagia (14/48). All patients who had dysphagia or odynophagia had endoscopic evidence of severe esophagitis, with confluent erosions or ulcerations. Gastrointestinal bleeding, which presented as melena or hematemesis, was caused by severe esophagitis in 11 of 12 patients. Yeasts were detected in 11/42 histological, or cytological specimens and were isolated in 4/26 cultures. No bleeding or infectious complications occurred in any patient as a result of the EGD procedure. We conclude that severe esophagitis documented by EGD is common in lymphoma patients receiving autologous BMT. Use of EGD, however, did not affect the decision to initiate empirical therapy with amphotericin B for persistent fever.