Time-kill studies of antimicrobial combinations including cefotaxime, ceftriaxone, vancomycin and meropenem against cephalosporin-resistant Streptococcus pneumoniae

Meropenem versus Cefotaxime and Ampicillin as Empirical Antibiotic Treatment in Adult Bacterial Meningitis: a Quality Registry Study, 2008 to 2016

Cefotaxime, alone or with ampicillin, is frequently used in empirical treatment of acute bacterial meningitis (ABM). Meropenem is a less extensively investigated alternative. The aim of the study was to investigate the effects of empirical treatment with meropenem compared to cefotaxime plus ampicillin on outcome in ABM. The study was based on data from the Swedish quality register for ABM collected between January 2008 and December 2016. Propensity score matching was performed to adjust for baseline differences between the groups. Mortality within 30 days was the primary outcome. The treatment regimens of interest were administered to 623 patients; 328 were given cefotaxime plus ampicillin whereas 295 received meropenem. Using propensity score matching, the 30-day mortality rates were 3.2% in the cefotaxime plus ampicillin group and 3.6% in the meropenem group. For matched cases, the odds ratio (OR) for 30-day mortality for meropenem versus cefotaxime plus ampicillin was 1.15 (confidence interval [CI], 0.41 to 3.22; P = 0.79). The OR for 90-day mortality was 1.47 (CI, 0.62 to 3.52; P = 0.38) and for unfavorable outcome was 1.10 (CI, 0.75 to 1.63; P = 0.62). The findings of our study indicate that meropenem is an effective empirical treatment option for adults with community-acquired ABM. However, to spare carbapenems, guidelines should continue to recommend third-generation cephalosporins as an empirical treatment for the majority of patients with ABM.

Neonatal bacterial meningitis: a systematic review of European available data

INTRODUCTION

Despite advances in neonatal intensive care and the improvements in surveillance, prevention and vaccination programs, neonatal meningitis still represents an important cause of morbidity and mortality in infants, with the highest mortality in the newborn population. The aim of this article was to summarize current knowledge about this topic with particular attention to management of neonatal meningitis in order to provide a useful tool for clinicians.

EVIDENCE ACQUISITION

We reviewed the existent literature from five European Countries (France, German, Italy, Spain and UK) on the effectiveness of treatments for bacterial meningitis in newborns taking into consideration the antibiotic resistance phenomenon.

EVIDENCE SYNTHESIS

There are few data available on this topic; bacterial neonatal meningitis treatment and management is currently based more on experience than on high quality evidences.

CONCLUSIONS

Identification of the knowledge gaps may stimulate researchers to design new studies aiming to better define management strategies of bacterial meningitis in newborns.

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.

[Antibiotic management of presumptive bacterial meningitis in adults (rational, methods, course, and follow-up)]

The annual incidence of community acquired meningitis ranges between 0.6 and four per 100,000 adults in industrialized countries. The most common causative bacteria are Streptococcus pneumoniae, Neisseria meningitidis, Listeria monocytogenes. The emergence of resistance to antibiotics, especially for S. pneumoniae, could explain the clinical failure of third generation cephalosporins used to treat adults with S. pneumoniae meningitis. The present therapeutic suggestions are more based on the extrapolation of an experimental model than on relevant clinical trials.

Evaluation of ceftriaxone, vancomycin and rifampicin alone and combined in an experimental model of meningitis caused by highly cephalosporin-resistant Streptococcus pneumoniae ATCC 51916

OBJECTIVES

The aim of the study was to assess the in vitro and in vivo efficacy of ceftriaxone, vancomycin and rifampicin alone and combined against Streptococcus pneumoniae ATCC 51916 (MIC of ceftriaxone: 32 mg/L).

METHODS

In vitro killing curves were performed with clinically achievable CSF antibiotic concentrations. In the rabbit model of pneumococcal meningitis, we studied the efficacy of and effects on inflammation of treatment with ceftriaxone 100 mg/kg/day, vancomycin 30 mg/kg/day and rifampicin 15 mg/kg/day, alone and combined, over a 26 h period.

RESULTS

Time-kill curves showed that vancomycin was bactericidal, and ceftriaxone and rifampicin produced a bacteriostatic effect. An additive effect was observed when combinations of ceftriaxone plus vancomycin were studied at subinhibitory concentrations. Emergence of resistance to rifampicin was detected both when rifampicin was studied alone and when combined with ceftriaxone or vancomycin. In the rabbit meningitis model, ceftriaxone was bacteriostatic, whereas rifampicin and vancomycin were bactericidal at 24 h. Although not synergistic, the combinations of ceftriaxone plus vancomycin or rifampicin, and vancomycin plus rifampicin, improved the efficacy of any antibiotic tested alone--all combinations were bactericidal from 6 h--and significantly decreased inflammatory parameters in CSF compared with control and ceftriaxone groups.

CONCLUSION

Ceftriaxone plus vancomycin, and vancomycin plus rifampicin appeared to be effective in the therapy of experimental pneumococcal meningitis caused by highly cephalosporin-resistant strains such as ATCC 51916. Our results provide an experimental basis for using these combinations as empirical therapy for pneumococcal meningitis, regardless of the degree of cephalosporin resistance of the causative strain.

Antimicrobial agents in the treatment of bacterial meningitis

The use of antimicrobial agents in the treatment of acute bacterial meningitis has undergone significant changes in recent years. There is a wealth of in vitro and animal model data that support the use of the specific antimicrobial agents in the treatment of bacterial meningitis, although not all regimens have been evaluated in clinical trials. Recent investigations have focused on expanding the potential antimicrobial formulary to manage patients with bacterial meningitis effectively in this era of increasing antimicrobial resistance. Despite these advances, the morbidity and mortality of acute bacterial meningitis remain unacceptably high. The use of adjunctive dexamethasone has been shown to improve morbidity and mortality in patients with bacterial meningitis, although concerns have been raised that dexamethasone may reduce penetration of certain antimicrobial agents into cerebrospinal fluid.

The management of bacterial meningitis in children

Bacterial meningitis is still a major cause of death and disability in children worldwide. With the advent of conjugate vaccines against the three major pathogens, the burden of disease is increasingly concentrated in developing countries that cannot afford the vaccines. Antibiotic resistance is an increasing problem; in developed countries, high-level resistance to beta-lactams among Streptococcus pneumoniae necessitates the addition of vancomycin to third-generation cephalosporins. In many developing countries, the problems are more fundamental. Increasing resistance of S. pneumoniae to penicillin and chloramphenicol and of Haemophilus influenzae to chloramphenicol means that many children with bacterial meningitis receive ineffective treatments, as third-generation cephalosporins are often unavailable or unaffordable. Case fatality rates are as high as 50% and neurological sequelae occur in one-third of survivors. The use of corticosteroids in meningitis is controversial; the evidence that they protect against neurological complications of childhood meningitis (particularly severe hearing loss) is strongest when: meningitis is caused by H. influenzae type b; dexamethasone is given before the first dose of antibiotics; a bactericidal antibiotic such as a third-generation cephalosporin is used; and in the early stages of the infection. There are few controlled clinical trials on which to base recommendations about other adjuvant therapy for meningitis. Avoidance of secondary brain injury from hypoxia, hypotension, hypo-osmolarity and cerebral oedema, hypoglycaemia or convulsions is essential for a good outcome. The problem of bacterial meningitis will only be solved if protein-conjugate vaccines (or other effective vaccine strategies) against S. pneumonia, H. influenzae and epidemic strains of Neisseria meningitidis are available to all the world's children. Making third-generation cephalosporins affordable in the developing world is also a necessary intervention, but better antibiotics will not overcome the problems of poor access to hospitals and late presentation with established brain injury, and will inevitably bring further pressure for antimicrobial resistance.

New therapies and vaccines for bacterial meningitis

Acute bacterial meningitis remains an important cause of morbidity and mortality worldwide. There have recently been major advances in the prevention of the major causes of bacterial meningitis following improvements in vaccinology. The success of immunisation against Haemophilus influenzae type b infection is being mirrored with serogroup C conjugated meningococcal vaccine and pneumococcal conjugate vaccine. However, there remain major challenges, notably, serogroup B meningococcal infection and shifts in epidemiology caused by vaccine introduction. In addition, much of the world's population is unvaccinated. Therefore, improvements in management of acute bacterial meningitis are vital. In this review we attempt to summarise important advances in both prevention and treatment of acute bacterial meningitis.