Tumour necrosis factor alpha induces only minor inflammatory changes in the central nervous system, but augments experimental meningitis

Although tumour necrosis factor alpha is said to play a key role in bacterial meningitis and other CNS diseases, the effects of this pro-inflammatory cytokine have only been studied in part and are incompletely understood. In a rat model, we investigated the effect of intracisternal injection of recombinant rat-specific tumour necrosis factor alpha (5, 35, 70 and 280 microg tumour necrosis factor alpha) (i) alone, (ii) combined with pneumococcal cell wall components, on regional cerebral blood flow, intracranial pressure, white blood cell count in the cerebrospinal fluid, and brain water content. Tumour necrosis factor a dose-dependently caused an increase in regional cerebral blood flow (up to 221 +/- 43% of baseline values) over the six hour observation period and mild cerebrospinal fluid leukocytosis; intracranial pressure and brain water content were unchanged. Hypothesizing that regional cerebral blood flow changes are dependent on nitric oxide, tumour necrosis factor alpha-induced regional cerebral blood flow increase was abolished by Aminoguanidine, a selective inhibitor of inducible nitric oxide synthase. Combination of the lowest tumour necrosis factor alpha dose and a low dose pneumococcal cell wall preparation magnified the inflammatory effect of both. We conclude that intrathecally injected tumour necrosis factor alpha alone results in only minor inflammatory changes, whereas it dramatically augments experimental meningitis.

Airway infection

Bronchitis in its acute and chronic forms with recurrent acute exacerbations is one of the most common reasons for physician visits, accounting for a significant cost to the health-care system, lost work days, and increased morbidity and mortality. Smoking and recurrent lower respiratory tract infections are major risk factors for chronic bronchitis. Therefore, smoking cessation and vaccination strategies are cornerstones of management in terms of halting disease progression and reducing the frequency of infectious exacerbations. Bacterial infection is the main culprit in acute flares of the disease. Routine antimicrobial therapy fails in a significant number of patients, and therapeutic failures lead to increased costs. Several stratification schemes have been proposed to improve initial antimicrobial selection. These schemes identify patient's age, severity of underlying pulmonary dysfunction, frequency of exacerbations, and the presence of comorbid illnesses as predictors for likely pathogens and to guide antimicrobial selection. This approach may reduce the risk for treatment failure, which would have significant medical and economic implications. Improved understanding of the roles of airway inflammation and infection in the pathogenesis of progressive airway disease, in addition to future studies examining the efficacy of newer classes of antimicrobials, should guide physicians to target early and effective treatment to high-risk patients.

[Which are the vaccines that human immunodeficiency virus infected patients must receive?]

Patients with aids are at increased risk of opportunistic and non opportunistic infections. It is now known that the incidence can be reduced by prophylactic measures and/or the use of vaccines. HIV infection produces an elevated frequency of severe pneumococcal disease with a rate of bacteriemia caused by Streptococcus pneumoniae 150-300 fold greater than rates reported in non-HIV infected people. For this reason, pneumococcal vaccine should be administered as early as possible in the course of the infection. Besides, the antibody response may be significantly higher for asymptomatic persons. Acute hepatitis caused by hepatitis B virus is milder than in non HIV infected patients but chronic disease is more frequent. The prognosis is worse and there is higher risk for infecting another persons. Hepatitis B vaccine is indicated for all the patients with HIV and negative serology for hepatitis B virus. Influenza vaccine is of limited effectiveness due to the high variability of the virus. Besides, influenza incidence is low among approximately young adults, HIV related immunodeficiency increased influenza risk only minimally, the vaccine is administered yearly and HIV-replication can increase in temporal association with vaccination. For all these reasons, fewer hospitalizations and deaths are prevented making it a far less cost-effective prevention strategy than pneumococcal vaccination. The risk of Haemophilus influenzae infections is elevated, but the vaccine is not routinely recommended because the more frequent serotype in HIV infected patients is b. For these subjects, passive immunization with immunoglobulin may also be necessary to provide protection. In conclusion, pneumococcal and hepatitis B vaccination is a reasonable prevention strategy for HIV infected patients at all stages of immunodeficiency. Influenza and H. influenzae vaccination are not recommended and alternative prevention strategies may be done.

Parenteral vs oral antibiotics in the prevention of serious bacterial infections in children with Streptococcus pneumoniae occult bacteremia: a meta-analysis

OBJECTIVE

To determine whether parenteral antibiotics are superior to oral antibiotics in preventing serious bacterial infections in children with Streptococcus pneumoniae occult bacteremia.

METHODS

Using the MEDLINE database, the English language literature was searched for all publications concerning bacteremia, fever, or Streptococcus pneumoniae from 1966 to January 1, 1997. All nonduplicative studies with a series of children with S. pneumoniae occult bacteremia having both orally treated and parenterally treated groups were reviewed. Children were excluded from individual studies if at the time of their initial evaluation they were immunocompromised, had a serious bacterial infection, underwent a lumbar puncture, or did not receive antibiotics.

RESULTS

Only 4 studies met study criteria. From these studies, 511 total cases of S. pneumoniae occult bacteremia were identified. Ten of 290 (3.4%) in the oral group and 5 of 221 (2.3%) in the parenteral antibiotic group developed serious bacterial infections (pooled p-value = 0.467, pooled OR = 1.48; 95% CI, 0.5-4.3). Two patients in the oral group (0.7%) and 2 patients in the parenteral group (0.9%) developed meningitis (pooled p-value = 0.699, pooled OR = 0.67; 95% CI, 0.1-5.1).

CONCLUSION

The rates of serious bacterial infections and meningitis did not differ between children who were treated with oral and parenteral antibiotics. The extremely low rate of complications observed in both groups suggests no clinically significant difference between therapies. A study with >7,500 bacteremic children (or >300,000 febrile children) would be needed to have 80% power to prove parenteral antibiotics are superior to oral antibiotics in preventing serious bacterial infections.

[Epidemiology of systemic Streptococcus pneumoniae infections]

OBJECTIVES

Invasive pneumococcal infections (bactereimia and meningitis) and pneumonia raise an authentic public health problem. We examined the epidemiology of these three different diseases.

METHODS

For bacteremia and meningitis, data were collected from the National Public Health network in France. Incidence of pneumonia was calculated by applying ratios published in the literature to three different types of incidence data (bacteremia, pneumonia hospitalizations in Haute-Savoie and community acquired pneumonia in general practices).

RESULTS

Annual incidence of meningitis was almost 1 per 100,000 inhabitants and 86 per 100,000 for bacteremia. Incidence was highest infants (< 5 years) and the elderly (> 65 years). All three of the calculation methods gave a convergent estimation of pneumonia cases with an average 132,000 cases per year, i.e., 220 per 100,000 inhibitants. This incidence was higher above 60 years of age. Death rate was unknown. Only 2.8% of the death certificates mentioned pneumonia. This give between 5,900 and 15,484 deaths, including 95% after the age of 60.

CONCLUSION

Pneumococcal infections remain an authentic public health problem, both in terms of morbidity and mortality.

[An autopsied case of purulent meningitis associated with ocular flutter]

We report a 72-year-old autopsied case of purulent meningitis associated with ocular flutter. She was admitted to our hospital because of disturbances of consciousness and fever. Physical examination revealed fever, tachycardia, and tachypnea. Neurological examination showed disturbance of consciousness (Japan Coma Scale 30), agitated state, anisocoria, sluggish and fixed reaction of pupils to light, and nuchal stiffness. Routine blood examination showed leukocytosis, thrombocytopenia, positive CRP, and elevated myocardial enzymes. Cerebrospinal fluid revealed pleocytosis with predominant leukocytes, elevated protein, and decreased glucose (22% of blood glucose), and Streptococcus pneumoniae was proved in culture. Brain CT scan revealed no abnormal findings. Electrocardiography showed tachycardia, left axis deviation, and elevated ST segment in aVF, and V3-V6. Ultrasonic echocardiography revealed slight hypokinesis of the left anterior wall, septum, and apex. She was diagnosed as having purulent meningitis, myocarditis, probable encephalitis. Thus, antibiotics, acycrovir, glycerol, and aspirin were administrated. But her respiration deteriorated and ocular flutter was observed for 15 minutes. After that, She required artificial ventilation and eventually died after 29 hours the admission to our hospital. Pathological examination revealed leukocyte accumulation in the arachnoid space of the derebral surface, especially frontal and parietal lobes. Uncal herniation was not observed. The brainstem and cerebellum were histologically within normal limits. These findings suggest that ocular flutter observed in this patient was caused by functional damage of the brainstem.

In vivo activity of HSR-903, a new fluoroquinolone, against respiratory pathogens

The in vivo activity of HSR-903, a new fluoroquinolone, against major bacteria which cause respiratory tract infections was evaluated. HSR-903 was active against experimental respiratory tract infections in mice challenged with penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae and Haemophilus influenzae strains. Treatment with HSR-903 reduced the bacterial numbers in infected murine lungs. In accord with the pulmonary clearance results, the rates of survival for mice treated with HSR-903, sparfloxacin, levofloxacin, ciprofloxacin, and benzylpenicillin were 50, 30, 10, 0, and 0%, respectively, 14 days after being infected with penicillin-resistant S. pneumoniae. A pharmacokinetic study with pneumonic mice showed that the levels of HSR-903 in the lungs were seven to eight times higher than those in the plasma. These results indicate that clinical studies of HSR-903 against respiratory tract infections may be warranted.

Septic sacroiliitis: an unusual causative organism in a rare condition

Streptococcus pneumoniae is a relatively uncommon cause of septic arthritis, and Infection of the sacroiliac joint by this organism has been rarely described. We present such a case.

Acute sinusitis in the rabbit model: histologic analysis

OBJECTIVES

Characterize the histology of the rhinogenic model of sinusitis and compare this with existing models of sinusitis.

STUDY DESIGN

Prospective controlled trial in animals.

METHODS

New Zealand white rabbits were implanted with a synthetic sponge, which was then impregnated with Streptococcus pneumoniae bacteria. After a specified time the animals were sacrificed, and whole-mount sectioning of both the infected and noninfected sinuses was performed. The sinuses were carefully examined for evidence of inflammatory changes.

RESULTS

This model produced a sinus infection that is characterized by luminal exudates of neutrophils and eosinophils, mucosal infiltration with lymphocytes and plasma cells, and epithelial degeneration. In addition, discrete lymphoid follicles were identified in both the implanted and nonimplanted sides that in the implanted sides appear to hypertrophy and liberate leukocytes into the sinus lumen. Other areas were observed where luminal exudates seem to act on and degrade mucosa that has little or no underlying inflammation. In severely infected sinuses submucosal vacuole formation with overlying granulation tissue was observed.

CONCLUSIONS

The rhinogenic model of sinusitis demonstrates features typical of other known models of sinusitis. In addition, there appear to be unique features of this model, specifically the identification of discrete lymphoid aggregates, which suggest that this model has the potential to be valuable for the study of the immune response of the sinuses.

Comparison of roxithromycin with cefixime in the treatment of adults with community-acquired pneumonia

This study compared the efficacy and tolerability of once-daily dosing with either roxithromycin or cefixime in previously healthy adult patients aged between 18 and 60 with markers of uncomplicated community-acquired pneumonia (CAP) in three outpatient clinics in an open, randomized study. Sixty patients were enrolled: 17 males and 13 females received roxithromycin 300 mg once daily for 8-10 days and 22 males and eight females received 400 mg cefixime once daily for the same period. All patients were assessed clinically, radiologically and bacteriologically before inclusion, immediately after the study and approximately 1 month later. The most common pathogen isolated from sputum was Streptococcus pneumoniae (in 26 (43%) of 60 patients), with mixed organisms isolated from the sputum of 18 (30%) of 60 patients. Staphylococcus aureus, Haemophilus influenzae or Moraxella catarrhalis occurred in 11/60 patients, and atypical pathogens were detected by serology in 7/26 cases in the roxithromycin group and 3/23 in the cefixime group. The severity of infection was rated as mild to moderate at the beginning of the trial. At the end of the study treatment period, clinical cure rates were 30/30 (100%) for roxithromycin and 28/30 (94%) for cefixime, with one patient on cefixime being classed as a partial responder and one patient being classed as a failure and withdrawn. However, radiological abnormalities persisted in three patients on roxithromycin and one on cefixime. Of the 59 patients who completed the study, none required further antibiotic therapy. No abnormal laboratory parameters or adverse events were reported in either group. Roxithromycin at a daily dose of 300 mg was an effective and well-tolerated treatment for the empirical treatment of mild to moderate CAP in this group of patients.

Comparison of roxithromycin with co-amoxiclav in patients with sinusitis

In an open, randomized study of 60 patients with acute or recurrent sinusitis, the bacteriological and clinical efficacy of roxithromycin 150 mg bd were compared with those of po co-amoxiclav (625 mg) tds. Of 52 patients who underwent sinus puncture for isolation of causative organisms, 48 had pathogens sensitive to both antibiotics. Satisfactory clinical response was obtained in 93.1% (27/29) evaluable patients receiving roxithromycin and 88.8% (24/27) receiving co-amoxiclav. Tolerability was significantly better in the roxithromycin group, with 1/29 (3.4%) patients in this group experiencing gastrointestinal side-effects, compared with 7/27 (25.9%) patients in the co-amoxiclav group (P < 0.05). Although the study had limited power to detect differences, roxithromycin demonstrated clinical, bacteriological and overall efficacy similar to that of co-amoxiclav, but with better tolerability. Roxithromycin thus appears to be an effective and well-tolerated drug for the treatment of acute and recurrent sinusitis.

A revised decision analysis of strategies in the management of febrile children at risk for occult bacteremia

Two decision analysis reports published in 1991 concluded that the strategy of routine blood culture and empiric antibiotics was the superior strategy for febrile children at risk for occult bacteremia. This report describes a decision analysis of treatment strategies for these children considering the following changes that have occurred since then: (1) Hemophilus influenzae B incidence is low because of widespread vaccine use; (2) the emergence of resistant Streptococcus pneumoniae may affect the clinical effectiveness of empiric antibiotics in the future; and (3) the negative consequences of unnecessary antibiotic treatment have yet to be well defined. A decision analysis approach, modifying the original assumptions, was carried out. Sensitivity analyses were conducted on all assumption variables. Strategies employing empiric antibiotics were found to have the best outcomes, assuming low negative treatment consequences. If a high level of negative treatment consequences is assumed, strategies using a white blood cell count (WBC) are superior. If a very high level of negative treatment consequences is assumed, the strategy of no tests and no empiric antibiotic treatment is usually superior, unless the frequency of bacteremia is 10% or higher and empiric antibiotic efficacy is high, in which case a WBC strategy is superior. This information can be used to select a treatment strategy based largely on the estimation of the negative consequences of treatment.

Effect of systemic pretreatment with betamethasone on the bacterial flora, inflammatory response, and polyp formation in experimentally infected rabbit maxillary sinus mucosa

To investigate possible effects of corticosteroids on polyp formation and local bacterial colonization, pneumococcal sinusitis was experimentally induced in rabbits pretreated with betamethasone or saline. After 7 days, macroscopic polyps were counted post-mortem and on histologic slides after serial sectioning. Histologic sections were also examined with light microscopy. Macroscopic polyps were significantly fewer in animals given betamethasone, while there was no difference regarding the number of microscopic polyps. Ingrowth of pathogenic microorganisms was found in five of eight rabbits given placebo but in none of the animals treated with corticosteroids (P < 0.05). The reduced number of pathogenic strains in these animals may be explained by a better-preserved local host defense. The lower number of macroscopic polyps in the same animals could be because of a delayed mucosal repair and subsequent polyp formation.

Colonisation and infection with resistant gram-positive cocci. Epidemiology and risk factors

Only a few years after the introduction of penicillin, resistant staphylococci were isolated in hospitals. This situation has led to the development of semisynthetic penicillins. Today, multiresistant Gram-positive bacteria have become an increasing problem in both hospitals and the community, frequently leaving the glycopeptides as the only therapeutic option. Notable problem pathogens are methicillin-resistant Staphylococcus aureus, coagulase-negative staphylococci and glycopeptide-resistant enterococci in the nosocomial environment, and penicillin-resistant Streptococcus pneumoniae in the community. In the hospital setting, as well as in the community and in animal husbandry, crowding and poor hygiene can facilitate the spread of resistant bacteria selected by antibiotic usage. However, the precise epidemiology and frequency of each drug-resistant pathogen depends on geographical location, the patient group involved and previous antibiotic use. Active measures need to be taken to reduce the spread of these pathogens and thus preserve the efficacy of available antibiotics.

Randomised trial of 23-valent pneumococcal capsular polysaccharide vaccine in prevention of pneumonia in middle-aged and elderly people. Swedish Pneumococcal Vaccination Study Group

BACKGROUND

We assessed the effectiveness of a 23-valent pneumococcal vaccine in the prevention of pneumococcal pneumonia and of pneumonia overall in non-immunocompromised middle-aged and elderly people.

METHODS

The prospective, multicentre, double-blind, randomised, placebo-controlled trial was carried out across departments of infectious diseases at six tertiary-care or university hospitals in Sweden. 691 non-immunocompromised patients aged 50-85 years who had been treated as inpatients for community-acquired pneumonia (CAP) were randomly assigned either 23-valent pneumococcal capsular polysaccharide vaccine or placebo (sodium chloride). We used Cox regression models to estimate the relative risks of pneumonia overall and pneumococcal pneumonia for the placebo group compared with the vaccine group.

FINDINGS

63 (19%) of 339 patients in the vaccine group and 57 (16%) of 352 patients in the placebo group developed a new pneumonia, corresponding to a relative risk over time for the placebo group compared with the vaccine group of 0.83 (95% CI 0.58-1.12, p=0.31). Pneumococcal pneumonia was diagnosed in 16 (4.5%) patients in the placebo group and in 19 (5.6%) in the vaccine group, corresponding to a relative risk for the placebo group of 0.78 (95% CI 0.40-1.51, p=0.45). We found no difference in the death rate between the two study groups.

INTERPRETATION

The 23-valent pneumococcal polysaccharide vaccine did not prevent pneumonia overall or pneumococcal pneumonia in middle-aged and elderly individuals.

Long-term gender-specific effects of manipulation during pregnancy on immune and endocrine responsiveness in rat offspring

Exposure to synthetic glucocorticoids (GCs) or other stimuli around birth may affect neuroendocrine and immune responsiveness in the offspring. Experiments were conducted to investigate whether maternal manipulation with saline or with GCs alters the corticosterone (CORT) response to a mild stressor in the offspring, and whether maternal manipulation results in long-term altered in vivo humoral and cellular immune responsiveness in the offspring. Pregnant rats were given dexamethasone (DEX, 1.2 mg/kg body weight, i.p.) or saline (SAL) at day 17 and 19 of gestation. A third group of pregnant rats was left undisturbed (UNTR-group). After maternal DEX treatment, no altered CORT response was seen to a novel environment at 20 days of age, as compared to both the SAL-treated group and the UNTR-group. However, saline administration to pregnant rats caused an increased CORT response in female offspring, but not male offspring, as compared to the UNTR-group (P < or = 0.01). Furthermore, no effects of maternal DEX exposure were seen on IgG2a production after immunization with a conjugated pneumococcal polysaccharide (PPS-14-CRM197) at 6 weeks of age. However, maternal SAL treatment enhanced anti-PPS-14 IgG2a antibody levels in female offspring, but not in male offspring, as compared to the UNTR-group (P < or = 0.05). Cellular immune responses were measured by an oxazolone-induced contact hypersensitivity response (CHS-response), at 8 weeks of age. Maternal SAL treatment increased the CHS response in adult male rats, but not in female rats, as compared to both the UNTR-group and the DEX-group (P < or = 0.005). These data suggest that manipulations during late pregnancy not only affect endocrine responsiveness, but also influence immune responsiveness in the rat offspring. Furthermore, these effects may be long-term and gender-specific.

Induction of labyrinthitis ossificans after pneumococcal meningitis: an animal model

Newly formed disorganized bone fills the open spaces within the otic capsule in various pathologic conditions, resulting in labyrinthitis ossificans. The pathologic mechanisms of this disease remain poorly understood. To better study the sequence of events and contributing mechanisms involved in labyrinthitis ossificans, an animal model was developed. Three groups of Mongolian gerbils received either an intralabyrinthine injection of normal saline solution (group 1) or Streptococcus pneumoniae polysaccharide capsule antigens (groups 2 and 3). The temporal bones were harvested after 3 months and serially sectioned. None of the eight control animals (group 1), which received intralabyrinthine injections of normal saline solution had any histologic changes in their temporal bones. Nine of the surviving 19 animals in groups 2 and 3 had fibrosis or evidence of early ossification. A fourth group of Mongolian gerbils received two intrathecal injections of live S. pneumoniae organisms. The temporal bones were harvested after 3 months and serially sectioned. Fourteen of the surviving 15 animals had fibrosis or ossification or both. This animal model will provide a method for study of the mechanisms of labyrinthitis ossificans.

Effects of exogenous cytokines on intravascular clearance of bacteria in normal and splenectomized mice

BACKGROUND

Pretreatment with interleukin-1 (IL-1), granulocyte colony-stimulating factor (G-CSF), and granulocyte macrophage colony-stimulating factor (GM-CSF) can improve alveolar macrophage bactericidal activity against pneumococci. These effects vary in eusplenic and asplenic mice. Likewise, these cytokines have been shown to improve survival after an aerosol pneumococcal challenge. Mice dying in these studies had positive blood cultures and disseminated infection. The purpose of this study was to determine the effect of cytokine pretreatment on intravascular clearance of bacteria from eusplenic and asplenic mice.

METHODS

Two weeks after splenectomy or sham operation, mice were pretreated for various times with IL-1, G-CSF, or GM-CSF or their corresponding vehicles. Mice then received tail-vein injections of bacteria (0.1 mL), and quantitative blood cultures were performed 15 and 30 minutes thereafter.

RESULTS

Splenectomized mice had impaired clearance of both pneumococci and Pseudomonas compared with sham-operated mice (p < 0.05). IL-1 enhanced clearance in splenectomized mice (p < 0.001) but not in sham-operated mice (p not significant). G-CSF enhanced bacterial clearance in sham-operated mice (p < 0.01) but not in splenectomized mice (p not significant). GM-CSF enhanced clearance in both groups (p < 0.001).

CONCLUSION

The net effects of exogenous cytokine therapy for infections depends on the state of the host defenses at the time of therapy. These agents may be useful as adjuvants for the treatment of infections, but further study is warranted.

Nebulized Surfactant for Experimentally Induced Otitis Media with Effusion

Eustachian tube dysfunction frequently results in clinical evidence of otitis media with effusion (OME). Surface active substances, surfactants, are hypothesized to play a role in normal eustachian tube function. Recent work in a rodent model has demonstrated improved eustachian tube function with topical application of surfactants to the middle ear. A novel, noninvasive, and clinically practical method of delivering surfactant to the eustachian tube was studied in a gerbil model of OME. Otitis media with effusion was experimentally induced in 20 gerbils by transtympanic inoculation of heat-killed Streptococcus pneumoniae. This represents a well established model for creating a serous effusion in the gerbil that significantly increases eustachian tube opening pressure. Effusion developed in 27 of 40 ears (67.5%) after inoculation. An inhaled nebulized surfactant was used to treat the animals with microscopically confirmed OME in one or both ears. The treatment period was 5 days. Eustachian tube opening studies were performed on both affected and nonaffected animals. Successful eustachian tube opening pressures were obtained in 30 of 36 ears (83.3%). The mean opening pressure for ears without effusion (healthy ears) was 42.8 mmHg. The mean opening pressure for ears with effusion in animals treated with nebulized surfactant was 41.4 mmHg. The difference between these mean values was not statistically significant ( t = 0.32; p > 0.50). This pilot study suggests that inhaled nebulized surfactant may be efficacious in treating eustachian tube dysfunction when manifested in disorders such as OME.