Effectiveness of ribosomal fractions of Klebsiella pneumoniae, Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and the membrane fraction of Kp (Ribomunyl) in the prevention of clinical recurrences of infectious rhinitis. Results of a multicenter double-blind placebo-controlled study

Current Stage in the Development of Klebsiella pneumoniae Vaccines

Klebsiella pneumoniae is a bacterium capable of colonizing mucous membranes, causing serious infections. Widespread antibiotic resistance in K. pneumoniae—either through intrinsic mechanisms or via acquisition from different species, especially in hospital environments—limits the therapeutic options against this pathogen, further aggravating the disease burden. To date, there are no vaccines available against K. pneumoniae infection. Although formulations based on capsular polysaccharides have been proposed, the high variability in capsular serotypes limits vaccine coverage. Recombinant vaccines based on surface exposed bacterial antigens are a promising alternative owing to their conservation among different serotypes and accessibility to the immune system. Many vaccine candidates have been proposed, some of which have reached clinical trials. The present review summarizes the current status of K. pneumoniae vaccine development. Different strategies including whole cell vaccines, outer membrane vesicles (OMVs), ribosome, polysaccharide, lipopolysaccharide (LPS), and protein-based formulations are discussed. The contribution of antibody and cell-mediated responses is also presented. In summary, K. pneumoniae vaccines are feasible and a promising strategy to prevent infections and to reduce the antimicrobial resistance burden worldwide.

Role of ribomunyl((r)) in the prevention of recurrent respiratory tract infections in adults : overview of clinical results

Recurrent respiratory tract infections (RRTIs) in adults are the result of an imbalance between lung defense mechanisms, and bacterial burden. Antibacterial treatments can temporarily restore the equilibrium between host and bacterial load, but do not prevent recurrence of infection. An alternative approach to prevent recurrence of infection is treatment with an immunostimulant, which provides immune protection against repeated bacterial and viral infection. All immunostimulant products are bacterial in origin: lysates (first generation immunostimulants), or bacterial extracts, like bacterial ribosomes, or membrane proteoglycans. This review highlights the current state of knowledge regarding the use of immunostimulants in adults with RRTIs, taking the ribosomal immunostimulant Ribomunyl((R)) as an example. Many studies are available on the mechanism of action and clinical efficacy in prevention of RRTIs in adults treated with Ribomunyl((R)). The effect of this immunostimulant on anti-infectious responses is explained by a stimulation of both nonspecific (innate) and specific (adaptive) immunity. In order to obtain a global overview of the therapeutic efficacy of Ribomunyl((R)) the most pertinent trials were selected from the literature based on adequate patient numbers and good methodology. Results of double-blind placebo-controlled trials using Ribomunyl((R)) for the treatment of different upper or lower RRTIs have demonstrated a statistically significant reduction in the number of infectious episodes and as a consequence, a decrease in antibacterial consumption, after 3 and 6 months of treatment. The tolerance profile of Ribomunyl((R)) was good in all studies. Economic evaluations suggest that savings can be made in healthcare expenditure, in patients with recurrent episodes of infection. It is concluded that Ribomunyl((R)) is effective in preventing and reducing upper and lower respiratory tract infections in adults. The product may also have an impact on reducing the development of bacterial resistance, as a result of fewer courses of antibacterials required to treat patients with RRTIs.

Oral vaccination: where we are?

As early as 900 years ago, the Bedouins of the Negev desert were reported to kill a rabid dog, roast its liver and feed it to a dog-bitten person for three to five days according to the size and number of bites [1] . In sixteenth century China, physicians routinely prescribed pills made from the fleas collected from sick cows, which purportedly prevented smallpox. One may dismiss the wisdom of the Bedouins or Chinese but the Nobel laureate, Charles Richet, demonstrated in 1900 that feeding raw meat can cure tuberculous dogs - an approach he termed zomotherapy. Despite historical clues indicating the feasibility of oral vaccination, this particular field is notoriously infamous for the abundance of dead-end leads. Today, most commercial vaccines are delivered by injection, which has the principal limitation that recipients do not like needles. In the last few years, there has been a sharp increase in interest in needle-free vaccine delivery; new data emerges almost daily in the literature. So far, there are very few licensed oral vaccines, but many more vaccine candidates are in development. Vaccines delivered orally have the potential to take immunization to a fundamentally new level. In this review, the authors summarize the recent progress in the area of oral vaccines.

Immunogenicity and protective efficacy offered by a ribosomal-based vaccine from Shigella flexneri 2a

Shigellosis is a major form of bacillary dysentery caused by Shigella infection. Shigella ribosome-based vaccines (SRV), considered among the potent vaccine candidates, are composed of O-antigen and ribosome isolated from S. flexneri 2a. To investigate the immunogenicity and protective efficacy of SRV, mice were vaccinated with SRV via the intranasal (i.n.) route. Interestingly, robust levels of Shigella-derived LPS-specific IgG and IgA Abs and antibody-forming cells were elicited in systemic and mucosal compartments following two i.n. administrations of SRV. Groups of mice receiving i.n. SRV developed milder pulmonary pneumonia upon challenge with virulent S. flexneri 2a than did those receiving parenteral SRV. We further found that the MyD88-dependent TLR2 signal partially mediates SRV-induced mucosal immunity, with the exception of TLR4- and TLR5-governed innate immunity. Most importantly, polymeric immunoglobulin receptor knockout (pIgR-/-) mice, which lack secretory IgA Ab, were afforded less protective efficacy than were wild-type mice. It can be concluded then that SRV is immunogenic and provides protective efficacy in mice. It can also be surmised that a mucosal SRV vaccine would be particularly relevant in targeting shigellosis, which provokes inflammation in the human colon.

Prevention of recurrent respiratory tract infections in children using a ribosomal immunotherapeutic agent: a clinical review

Recurrent respiratory tract infections (RRTIs) in children constitute a serious problem worldwide. Some children experience considerable morbidity as a result of RRTIs and receive repeated courses of antibacterials that are not effective against viral infectious agents and can increase bacterial resistance. Furthermore, the direct and indirect costs of RRTIs to the community are substantial. In this article, we review the available clinical evidence relating to use of the bacterial immunostimulant Ribomunyl for the prevention of RRTIs in children. The product is composed of ribosomal fractions from four bacteria involved in RRTIs as well as a membrane fraction from one of these bacteria (Klebsiella pneumoniae). Ribomunyl stimulates production of specific humoral and secretory antibodies against the four bacterial strains included in the compound. The product also stimulates non-specific immunity. Thus, Ribomunyl stimulates both the innate and acquired immune systems and offers preventive efficacy against both bacterial and viral infections. To perform this review, we searched the MEDLINE database for articles on Ribomunyl and then included only those publications that described placebo-controlled studies, complied with Good Clinical Practice standards, used the product in official registered indications, and administered it at the recommended dosages. In this way, we were able to generate a comprehensive profile of use of the product and draw valid conclusions about its clinical role. In clinical trials of children, Ribomunyl reduced the number of upper or lower RRTIs, the primary outcome measures. Other favorable results relating to efficacy parameters that served as secondary outcome measures in these studies included a reduction in antibacterial treatments, shorter duration of recurrent episodes, reduced need for other medications such as expectorants, smaller number of lost school days or parent absenteeism from work, less fever, and reduced hearing loss. Studies focusing on particular conditions, such as otitis media, or those that included specific patient groups, such as very young children, reported similar findings. Adverse events occurred very rarely and were mild. Their frequency was similar to that reported in placebo groups, and consisted mostly of fever, otorhinolaryngologic symptoms, and cutaneous events. In conclusion, this review clearly demonstrated that Ribomunyl is effective in preventing upper and lower RRTIs in children. Ribomunyl provided a reduction in the number, duration, and severity of infectious episodes and, thereby, reduced antibacterial use and the likelihood of consequent development of bacterial resistance. Ribomunyl also decreased absence from work or school, which has important economic consequences.

Immunostimulants revisited: focus on the pharmacology of Ribomunyl

Ribomunyl is an immunostimulant that was developed and commercialized in the 1980s in France and has subsequently been made available in a large number of countries. The formulation is composed of proteoglycans from Klebsiella pneumoniae and of ribosomes from four of the most commonly encountered bacterial strains in recurrent respiratory tract infections. While it is obviously difficult to present a thorough summary of all historical data, here we revisit the mode of action of this immunostimulant and present a perspective in the context of the most recent data and hypotheses on the mechanisms of the antibacterial immune responses. We provide various examples of these mechanisms in innate immunity (phagocytosis, cell adhesion, dendritic cell maturation, Toll-like receptors, interferon production, proinflammatory cytokines, activation of natural killer cells), as well as in adaptative immunity (polyclonal activation of T and B cells, specific immunoglobulin A immune response in an integrated view of the mucosal immune system, and T helper type 1/type 2 [Th1/Th2] regulation and balance). The effect of this immunostimulant on anti-infectious responses can be explained, not only by a stimulation of the antibacterial defense directly assumed by innate immunity, but also by a stimulation of the specific (adaptative) immune response related to the activation of dendritic cells, of which the pivotal role in T-cell differentiation is already well known. This supports the potential of bacterial immunostimulants such as Ribomunyl in anti-infective therapy.

Maximal medical therapy for chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is widely recognized as one of the most common, if not the most common, chronic disease entities. This article discusses CRS without nasal polyposis. The discussion of maximal medical therapy concentrates on the best available evidence from published clinical trials.

Mucosal AIDS vaccines

Debates are still being waged over what is the best strategy for developing a potent AIDS vaccine. All the obvious approaches to making AIDS vaccines have been tried in the past two decades without much success. It is clear that new thinking and a revision of prevailing dogmas needs to be in place if we really want a vaccine. Conventional envelope-based antibody-inducing vaccines do not appear to hold promise, and broadly-neutralizing antibodies are now being searched as an alternative to the failed approach with subunit vaccines. The current consensus is that cellular immune responses, especially those mediated by CD8 cytotoxic/suppressor (CTL) and CD4 helper T lymphocytes, are needed to control HIV. Vaccines capable of inducing cell-mediated responses are, therefore, considered critical for controlling the spread of HIV. DNA-based vaccines triggering CTL reaction are currently thought to be an answer, but will they fulfill the promise? In the following paragraphs, a critical assessment of the state of the art will be provided in an attempt to analyze what we know and still don't know. The focus of this review is primarily on mucosal vaccines-a relatively new area in AIDS research. The update on V-1 Immunitor, the first mucosal AIDS vaccine available commercially, is provided within this context. Some of the reviewed concepts may be disputable, but without departure from the uninspiring consensus no substantial progress in the AIDS vaccine field can be envisioned.

Ribosomal immunostimulation: assessment of studies evaluating its clinical relevance in the prevention of upper and lower respiratory tract infections in children and adults

OBJECTIVE

To review the efficacy of the ribosomal immunostimulant Ribomunyl in preventing upper and lower respiratory tract infections.

DESIGN AND SETTING

Review of studies of 3 and 6 months' duration comprising part of the international registration file.

PATIENTS

Data from 2117 patients (1215 children and 902 adults); ribosomal immunostimulant n = 1062, placebo n = 1055.

RESULTS

Nineteen randomised, double-blind, placebo-controlled clinical trials were performed between 1983 and 1994 in Europe. In children with ear-nose-throat (ENT) infections, 3 months' ribosomal immunostimulant treatment significantly decreased the mean number of recurrences (27-68% reduction), and reduced the duration of infection (28-66% reduction) and antibacterial requirement (29-60% reduction). Ribosomal immunostimulant was similarly effective in children with ENT and bronchopulmonary infections, reducing the mean number of recurrences by 32-61% compared with placebo. In children with otitis media, ribosomal immunostimulant reduced recurrences by 10-53% and also reduced the duration of infection, antibacterial use and local surgery requirement. Results obtained from studies of 6 months' duration confirmed or extended these results. In adult patients with ENT or mixed respiratory infections, ribosomal immunostimulant produced similar reductions to those seen in children for recurrent infections (54-78% reduction), duration of infection (42-79% reduction) and antibacterial use (38% reduction).

CONCLUSIONS

These results clearly demonstrate that ribosomal immunostimulant is effective in preventing and in reducing upper and lower respiratory tract infections in children and adults.

Ribosomal immunotherapy for recurrent respiratory tract infections in children

Recurrent respiratory tract infections are common in children. They reflect the immaturity of the immune system in its encounter with environmental antigens. Little or no specific protective immune response has yet been established. These infections represent an important public health problem in terms of both treatment (anti-inflammatory or antibacterial drugs for children) and economy. Immunotherapy has been proposed as a means of preventing these recurrent infections by providing children with small doses of inactive bacterial antigens liable to trigger specific and protective immune responses. Among such drugs, ribosomal preparations (to which this review is limited) appear to be not only well tolerated, but also ideally targeted to induce mucosal responses. One preparation of ribosomal mucosal vaccine is commercially available in several countries. Numerous clinical trials in the world have confirmed the positive role of this mucosal ribosomal bacterial vaccine in significantly reducing the number of infections, courses of antibacterials, and absenteeism. In vitro and ex vivo investigations have confirmed that such vaccines indeed trigger protective specific immune responses.

A preventive measure for otitis media in children with upper respiratory tract infections

Recurrent upper respiratory tract infections (URTI) are very common in patients of all ages. Rhinitis, bronchitis, chronic sinusitis and otitis appear to be the prevalent forms of recurrent respiratory infections in the paediatric population. The aim of treatment is so the solution of the respiratory pathology and the also the prevention of their complications. Antibacterial therapy is still the classical treatment approach in patients both with respiratory tract infections and with otitis media, despite the fact that antibacterials have several well known drawbacks, especially when used to treat recurrent infections. Eighty-four paediatric patients of both sexes (range: 4-14 years) with otitis were enrolled in the study. Patients were included if they had a >2 years' history of recurrent or chronic respiratory infections, and/or had experienced at least three episodes requiring medical consultations and/or treatment during the winter prior to the study. The young patients were randomised to receive Immucytal (group A) or placebo (group B) treatment according to the following protocol: (1) starting therapy (1 month): one tablet daily in the morning 4 days per week for 3 consecutive weeks; (2) maintenance period (5 months): one tablet daily in the morning 4 days per week for 1 week every month. Placebo and Immucytal tablets were identical in shape and size, in order to maintain double-blind conditions. Patients of group A with recurrent URTI had a significantly decreased incidence of ENT infections, fever and shorter duration of illness, decreased requirement for ancillary medications and fewer work-days lost. The reduction in the incidence of infectious episodes became significant vs. placebo. A significantly improved outcome vs. placebo was also observed on the incidence of fever, frequency and duration of infectious episodes, ancillary therapies. Immucytal treatment was associated with significant changes in both immunological and auditory function parameters. Serum concentrations of immunoglobulins were significantly increased in Immucytal. For both evaluations, a significant difference between treatment groups was found (P>0.001). Preventive strategies, such as ribosomal immunotherapy, may represent a valid alternative approach.

Analysis of recurrent failure times data: should the baseline hazard be stratified?

Over the past two decades, a variety of fruitful statistical methods for the analysis of recurrent events has been proposed for the estimation of covariates effect using the Cox proportional hazard model. Besides frailty modelling, two simple trends of modelling have been developed: the first one uses stratification on the rank of the event, whereas the second one, more closely related to Poisson processes theory, does not use stratification. Although they both take into account the correlation of the unit failure times, each of these approaches emphasizes a different aspect of the underlying point process and there is still an ongoing debate concerning the most appropriate method. The aim of this paper is to stress current interests and trends concerning these two approaches. For each model, main statistical methods for estimating the covariates effects are presented. Methods are illustrated and compared in two randomized clinical trials which involve recurrences of severe adverse events following chemotherapy in 938 patients with chronic lymphocytic leukaemia, and recurrences of infectious rhinitis episodes in 327 patients. The discussion, based on the previous examples and on the properties of underlying statistical inference, deals with the appropriateness of the model choice, which is closely related to the data structure.

Estimation of the treatment effect in a clinical trial when recurrent events define the endpoint

Recurrent events are frequently encountered in clinical trials when individuals may experience an event more than once. Examples are common in medical research, including infectious episodes, myocardial infarctions and hospital admissions. However, when only the first event is considered, there is a loss of information. Furthermore, the analysis of recurrent events is complicated by the dependence of the related failure times of each subject, that is, the occurrence of an event influences the risk of other events. Thus, naive statistical methods that consider recurrent events as independent observations will produce misleading conclusions. We recommend the use of a marginal hazards model that is derived from the multivariate generalization of the Cox proportional hazards model. This marginal model allows estimation of the relative risk of recurrence in clinical trials, taking into account the dependence between the recurring events of a same individual without explicit modelling. Two applications are used to compare the results of the marginal model analysis with those of usual methods: (i) a placebo-controlled randomized clinical trial performed to evaluate the efficacy of an immunostimulant in the prevention of recurrences of infectious rhinitis in adults; (ii) a randomized clinical trial comparing transfusions of plasma rich in anti-HIV1 versus transfusions of seronegative plasma in the prevention of opportunist infections. To analyse recurrent events, usual methods are often irrelevant and the marginal model allows use of all the available information to accurately estimate the relative risk of recurrences. Moreover, it enables the estimation of the relative risk for each rank of recurrence.

Use of diagnostic clusters to assess the economic consequences of rhinopharyngitis in children in Italy and France during the winter. Rhinitis Survey Group

To determine how practitioners diagnose rhinopharyngitis (RP), we conducted a longitudinal, multicenter study of a cohort of 900 children, collecting medical and economic data without interfering with usual medical practice during the winter of 1996-1997 in France and Italy. All ear, nose, and throat (ENT) infections were described clinically; data on the consumption of medical items (physician visits, drug treatment, hospitalization, physiotherapy, preventive treatment, laboratory tests, roentgenograms, and outpatient procedures) were collected to estimate the cost of caring for patients with RP. The mean age of the children was 28.0 months, and the ratio of males to females was approximately 5 to 4. Patients had had a mean 4.1 episodes of RP the previous year and 1.4 episodes of acute otitis media (AOM). There were no marked differences in the children's characteristics between France and Italy. During the winter of the study, this population experienced 4.26 episodes of ENT infection, of which 73.5% were documented at the study sites. Seven homogeneous groups of RP were found, 2 of them each representing <4% of the overall population. One group presented with otalgia, although the diagnosis of AOM was not recorded by the physician. In 4 groups, the presence of nasal discharge plus cough (without otalgia) was used to make the diagnosis. Medical item consumption varied by country and by group of RP, mainly in the prevailing choice of antibiotics. The difference in duration of treatment was not statistically significant. As a consequence, the costs of caring for patients with RP varied greatly, RP with AOM being the most costly. Last, prognostic factors for costly episodes of infectious ENT were identified. The population at risk included young children who had had AOM episodes during the previous winter, had a first episode of AOM before 6 months of age, had a history of AOM associated with effusion, or attended a community-based child care facility. Therefore, clinical trials aimed at demonstrating cost-effectiveness of prophylaxis should focus on this population.