Antivirals for influenza: what is their role in the older patient?

Role of Fat-Soluble Vitamins A and D in the Pathogenesis of Influenza: A New Perspective

Reduced exposure to solar radiation, leading to a deficiency of vitamin D and hence impaired innate immunity, has been suggested as a trigger for influenza viral replication and as an explanation of seasonal influenza. Although this hypothesis accounts for many unexplained facts about the epidemiology of influenza, gaps remain in understanding the pathogenesis and manifestations of the disease. Several observations suggest a role for vitamin A compounds (retinoids) in the disease. This paper presents a new model of the etiopathogenesis of influenza, suggesting that host resistance and susceptibility depend importantly on the ratio of vitamin D to vitamin A activity. Retinoid concentrations within normal physiological limits appear to inhibit influenza pathogenesis whereas higher background concentrations (i.e., very low vitamin D : A ratios) increase the risk of severe complications of the disease. There is also evidence that influenza-induced or preexisting liver disease, diabetes, and obesity worsen the severity of infection, possibly via liver dysfunction and alterations in retinoid metabolism. The model could be tested by determining the presence of retinoids in the secretions of patients with influenza and by studies of retinoid profiles in patients and controls. Potential strategies for prevention and treatment are discussed.

Frequency of drug-resistant viruses and virus shedding in pediatric influenza patients treated with neuraminidase inhibitors

BACKGROUND

Although influenza virus resistance to the neuraminidase inhibitor zanamivir is reported less frequently than is resistance to the neuraminidase inhibitor oseltamivir in clinical settings, it is unknown whether this difference is due to the limited use of zanamivir or to an inherent property of the drug. We therefore compared the prevalence of drug-resistant viruses and virus shedding in seasonal influenza virus-infected children treated with either oseltamivir or zanamivir.

METHODS

Clinical specimens (throat or nasal swab) were collected from a total of 144 pediatric influenza patients during the 2005-2006, 2006-2007, 2007-2008, and 2008-2009 influenza seasons. Neuraminidase inhibitor-resistant mutants were detected among the isolated viruses by sequencing the viral hemagglutinin and neuraminidase genes. Sensitivity of the viruses to neuraminidase inhibitors was tested by neuraminidase inhibition assay.

RESULTS

In oseltamivir- or zanamivir-treated influenza patients who were statistically comparable in their age distribution, vaccination history, and type or subtype of virus isolates, the virus-shedding period in zanamivir-treated patients was significantly shorter than that in oseltamivir-treated patients. Furthermore, the frequency of zanamivir-resistant viruses was significantly lower than that of oseltamivir-resistant viruses.

CONCLUSION

In comparison with treatment with oseltamivir, treatment of pediatric patients with zanamivir resulted in the emergence of fewer drug-resistant influenza viruses and a shorter virus-shedding period. We conclude that zanamivir shows promise as a better therapy for pediatric influenza patients.

Top ten list of long-term care facility preparations for the upcoming influenza season

A novel influenza A partly of virus of swine origin (2009 H1N1) emerged this spring, resulting in an influenza pandemic. This pandemic is anticipated to continue into the next influenza season. Given that the 2009 H1N1 and seasonal influenza A appear to be somewhat different in the human populations affected and that two influenza vaccines will be recommended this fall, those who manage long-term care facilities and treat patients in them will be faced with many uncertainties as they approach the 2009/10 influenza season. Ten specific suggestions are offered to those responsible for the care of patients in long-term care facilities regarding the upcoming influenza season. These practical suggestions are the clinical opinions of the authors and do not represent official recommendations of the American Geriatrics Society or any agency.

Unique aspects of antimicrobial use in older adults

Elderly persons consume a significant proportion of health care resources. Antimicrobials are just one class among many pharmaceuticals that are prescribed more frequently to elderly patients than to younger patients. There are unique aspects of antimicrobial use in elderly persons that make prescribing complicated and monitoring unpredictable. Physiologic changes associated with aging result in altered pharmacokinetics, and accurate estimates of renal function cannot be made with standard methods. Together, these qualities make antimicrobial dosing difficult. Because of a higher prevalence of other chronic diseases, there is a greater propensity for polypharmacy and a resulting risk of an adverse event or a significant drug interaction. Lastly, irrespective of altered pharmacokinetics, adverse effects of many antimicrobials are more common in elderly persons, which introduces an added dimension to ensuring safety with antimicrobial therapy.

Acute bronchitis: state of the art diagnosis and therapy

In managing acute bronchitis, pneumonia or an exacerbation of underlying chronic bronchitis should be excluded. Simple bronchitis is best treated symptomatically while an exacerbation of chronic bronchitis can be treated with antibiotics. Broad spectrum antibiotics are appropriate in selected patients.