Emerging drugs for acute bacterial meningitis

Bacterial meningitis: new treatment options to reduce the risk of brain damage

Introduction: Bacterial meningitis (BM) is a medical emergency and its etiology varies according to the age group and geographic area. Studies have shown that brain damage, sequelae and neuropsychological deficits depend not only on the direct deleterious action of the pathogens, but also on the host defenses themselves.Areas covered: Corticosteroids (CS) were the first drugs used with the intent to limit the exaggerated host response. However, as steroid addition to antibiotics is frequently unsatisfactory, other measures have been suggested. In this study, the most important adjuvant therapies that are potentially useful to limit the neuropsychological damage of BM are discussed.Expert opinion: The pathophysiological mechanisms leading to the development of brain damage are not completely defined. Moreover, the efficacy of adjuvant therapies can vary according to the aetiologic cause of BM, and differences in immune system function of the host can play a relevant role in the expression of inflammation and related problems. It is likely that none of the measures with demonstrated efficacy in animal models can be translated into clinical practice in the next few years, suggesting that to reduce the total burden of BM, the increased use of vaccines seems to be the best solution.

Central Nervous System Infections

Central nervous system (CNS) infections—i.e., infections involving the brain (cerebrum and cerebellum), spinal cord, optic nerves, and their covering membranes—are medical emergencies that are associated with substantial morbidity, mortality, or long-term sequelae that may have catastrophic implications for the quality of life of affected individuals. Acute CNS infections that warrant neurointensive care (ICU) admission fall broadly into three categories—meningitis, encephalitis, and abscesses—and generally result from blood-borne spread of the respective microorganisms. Other causes of CNS infections include head trauma resulting in fractures at the base of the skull or the cribriform plate that can lead to an opening between the CNS and the sinuses, mastoid, the middle ear, or the nasopharynx. Extrinsic contamination of the CNS can occur intraoperatively during neurosurgical procedures. Also, implanted medical devices or adjunct hardware (e.g., shunts, ventriculostomies, or external drainage tubes) and congenital malformations (e.g., spina bifida or sinus tracts) can become colonized and serve as sources or foci of infection. Viruses, such as rabies, herpes simplex virus, or polioviruses, can spread to the CNS via intraneural pathways resulting in encephalitis. If infection occurs at sites (e.g., middle ear or mastoid) contiguous with the CNS, infection may spread directly into the CNS causing brain abscesses; alternatively, the organism may reach the CNS indirectly via venous drainage or the sheaths of cranial and spinal nerves. Abscesses also may become localized in the subdural or epidural spaces. Meningitis results if bacteria spread directly from an abscess to the subarachnoid space. CNS abscesses may be a result of pyogenic meningitis or from septic emboli associated with endocarditis, lung abscess, or other serious purulent infections. Breaches of the blood–brain barrier (BBB) can result in CNS infections. Causes of such breaches include damage (e.g., microhemorrhage or necrosis of surrounding tissue) to the BBB; mechanical obstruction of microvessels by parasitized red blood cells, leukocytes, or platelets; overproduction of cytokines that degrade tight junction proteins; or microbe-specific interactions with the BBB that facilitate transcellular passage of the microorganism. The microorganisms that cause CNS infections include a wide range of bacteria, mycobacteria, yeasts, fungi, viruses, spirochaetes (e.g., neurosyphilis), and parasites (e.g., cerebral malaria and strongyloidiasis). The clinical picture of the various infections can be nonspecific or characterized by distinct, recognizable clinical syndromes. At some juncture, individuals with severe acute CNS infections require critical care management that warrants neuro-ICU admission. The implications for CNS infections are serious and complex and include the increased human and material resources necessary to manage very sick patients, the difficulties in triaging patients with vague or mild symptoms, and ascertaining the precise cause and degree of CNS involvement at the time of admission to the neuro-ICU. This chapter addresses a wide range of severe CNS infections that are better managed in the neuro-ICU. Topics covered include the medical epidemiology of the respective CNS infection; discussions of the relevant neuroanatomy and blood supply (essential for understanding the pathogenesis of CNS infections) and pathophysiology; symptoms and signs; diagnostic procedures, including essential neuroimaging studies; therapeutic options, including empirical therapy where indicated; and the perennial issue of the utility and effectiveness of steroid therapy for certain CNS infections. Finally, therapeutic options and alternatives are discussed, including the choices of antimicrobial agents best able to cross the BBB, supportive therapy, and prognosis.

Acute bacterial meningitis in infants and children: epidemiology and management

Acute bacterial meningitis (ABM) continues to be associated with high mortality and morbidity, despite advances in antimicrobial therapy. The causative organism varies with age, immune function, immunization status, and geographic region, and empiric therapy for meningitis is based on these factors. Haemophilus influenzae type b (Hib), Streptococcus pneumoniae, and Neisseria meningitidis cause the majority of cases of ABM. Disease epidemiology is changing rapidly due to immunization practices and changing bacterial resistance patterns. Hib was the leading cause of meningitis in children prior to the introduction of an effective vaccination. In those countries where Hib vaccine is a part of the routine infant immunization schedule, Hib has now been virtually eradicated as a cause of childhood meningitis. Vaccines have also been introduced for pneumococcal and meningococcal diseases, which have significantly changed the disease profile. Where routine pneumococcal immunization has been introduced there has been a reported increase in invasive pneumococcal disease due to non-vaccine serotypes. In those parts of the world that have introduced conjugate meningococcal vaccines, there has been a significant change in the epidemiology of meningococcal meningitis. As a part of the United Nations Millennium Development Goal 4, the WHO has introduced a new vaccine policy to improve vaccine availability in resource poor countries. In addition, antibiotic resistance is an increasing problem, especially with pneumococcal infection. Effective treatment focuses on early recognition and use of effective antibiotics. This review will attempt to focus on the changing epidemiology of ABM in pediatric patients due to vaccination, the changing patterns of infecting bacterial serotypes due to vaccination, and on antibiotic resistance and its impact on current management strategies.

Immediate outcomes of bacterial meningitis in childhood may benefit from slow initial β-lactam infusion and oral paracetamol

Evaluation of: Pelkonen T, Roine I, Cruzeiro ML, Pitkaranta A, Kataja M, Peltola H. Slow initial β-lactam infusion and oral paracetamol to treat childhood bacterial meningitis: a randomised, controlled trial. Lancet Infect. Dis. 11(8), 613-621 (2011). Acute bacterial meningitis is a medical emergency that requires prompt management. Despite effective antibiotic and adjunctive therapies, mortality is still unacceptably high in acute bacterial meningitis in children as this mortality did not substantially improve since the first use of antimicrobial therapies in the mid-20th century. β-lactams and particularly third-generation cephalosporins (ceftriaxone or cefotaxime) penetrate most body tissues and fluids, such as the cerebrospinal fluid, well. They are effective against the three most frequent bacterial causative agents of acute bacterial meningitis (Neisseria meningitidis, Streptococcus pneumoniae and Hemophilus influenzae). They are currently the consensual choices for the presumptive treatment of acute bacterial meningitis and usually used as a bolus every 4-6 h. Pelkonen et al. published a prospective, double-blind, single-center study with a two-by-two factorial design that aimed to explore the benefits in children of infused compared with bolus cefotaxime administration. Each group (bolus and infusion) was divided into two subgroups (with oral paracetamol or with placebo). No significant difference was observed for the final outcomes (mortality or severe neurological sequela and deafness) in the four subgroups. However, a post-hoc analysis of the results suggested that cefotaxime infusion plus paracetamol recipients had significant lower mortality during the first 72 h, irrespective of causative agents. However, the relevance of this study in sub-Saharan Africa is still difficult to evaluate as more than half of the initially assessed patients did not meet the inclusion criteria. The extension of the conclusions to developed countries may require further evaluations in terms of pharmacokinetic/pharmacodynamic properties as well as a thorough characterization of the causative agents under the view of the heterogeneous genetic structure of circulating bacterial strains in developed countries.

Therapeutic management of bacterial meningitis in children: a systematic review and comparison of published guidelines from a European perspective

Bacterial meningitis is an infectious disease emergency that can cause substantial morbidity and mortality. We compared the most recent international guidelines and recommendations on bacterial meningitis management in infants and children in developed countries, in terms of initial management approach, empirical antimicrobial therapy, timing, dosages, and duration of antimicrobial therapy, and possible adjunctive treatment with dexamethasone. Secondly, epidemiological data on bacterial resistance in several european countries were analyzed and discussed in relation to the therapies currently recommended for bacterial meningitis. The comparative analysis of the selected guidelines highlighted significant differences in the therapeutic management of bacterial meningitis. Differences among guidelines have important consequences for daily practice. An agreed protocol for early, evidence-based, and effective therapeutic management of bacterial meningitis is essential for the best outcome. further studies and expert consensus are required to establish the best management of bacterial meningitis in the european setting based on the most recent epidemiological data on resistance rates.