Fluoroquinolones in the Treatment of Meningitis

Effect of seven anti-tuberculosis treatment regimens on sputum microbiome: a retrospective analysis of the HIGHRIF study 2 and PanACEA MAMS-TB clinical trials

BACKGROUND

Respiratory tract microbiota has been described as the gatekeeper for respiratory health. We aimed to assess the impact of standard-of-care and experimental anti-tuberculosis treatment regimens on the respiratory microbiome and implications for treatment outcomes.

METHODS

In this retrospective study, we analysed the sputum microbiome of participants with tuberculosis treated with six experimental regimens versus standard-of-care who were part of the HIGHRIF study 2 (NCT00760149) and PanACEA MAMS-TB (NCT01785186) clinical trials across a 3-month treatment follow-up period. Samples were from participants in Mbeya, Kilimanjaro, Bagamoyo, and Dar es Salaam, Tanzania. Experimental regimens were composed of different combinations of rifampicin (R), isoniazid (H), pyrazinamide (Z), ethambutol (E), moxifloxacin (M), and a new drug, SQ109 (Q). Reverse transcription was used to create complementary DNA for each participant's total sputum RNA and the V3-V4 region of the 16S rRNA gene was sequenced using the Illumina metagenomic technique. Qiime was used to analyse the amplicon sequence variants and estimate alpha diversity. Descriptive statistics were applied to assess differences in alpha diversity pre-treatment and post-treatment initiation and the effect of each treatment regimen.

FINDINGS

Sequence data were obtained from 397 pre-treatment and post-treatment samples taken between Sept 26, 2008, and June 30, 2015, across seven treatment regimens. Pre-treatment microbiome (206 genera) was dominated by Firmicutes (2860 [44%] of 6500 amplicon sequence variants [ASVs]) at the phylum level and Streptococcus (2340 [36%] ASVs) at the genus level. Two regimens had a significant depressing effect on the microbiome after 2 weeks of treatment, HR20mg/kgZM (Shannon diversity index p=0·0041) and HR35mg/kgZE (p=0·027). Gram-negative bacteria were the most sensitive to bactericidal activity of treatment with the highest number of species suppressed being under the moxifloxacin regimen. By week 12 after treatment initiation, microbiomes had recovered to pre-treatment level except for the HR35mg/kgZE regimen and for genus Mycobacterium, which did not show recovery across all regimens. Tuberculosis culture conversion to negative by week 8 of treatment was associated with clearance of genus Neisseria, with a 98% reduction of the pre-treatment level.

INTERPRETATION

HR20mg/kgZM was effective against tuberculosis without limiting microbiome recovery, which implies a shorter efficacious anti-tuberculosis regimen with improved treatment outcomes might be achieved without harming the commensal microbiota.

FUNDING

European and Developing Countries Clinical Trials Partnership and German Ministry of Education and Research.

Fluoroquinolones: Blessings Or Curses

Fluoroquinolones are one of the world's most valuable and popularly used categories of antimicrobial agents. This paper attempts to review the substantial progress of fluoroquinolones from their discovery to black box warning. Antibiotic drug choice will remain difficult in the presence of increasing resistance, but the introduction of fluoroquinolones has created a new and exciting era in antimicrobial treatment. These are a synthetic heterogeneous group of compounds used in both hospital and community practices to treat numerous severe infections. The era of quinolone antibiotics began with the serendipitous discovery of the quinolone prototype in 1962. The chronological development of fluoroquinolone reported that nalidixic acid was the first quinolone that gained popular choice for the treatment of urinary tract infection. The subsequent agents like levofloxacin, ofloxacin, norfloxacin, gatifloxacin, moxifloxacin, clinafloxacin, sparfloxacin, and ciprofloxacin were derived through side chain and nuclear manipulation from basic pharmacophore. The fluoroquinolone motifs have been found as a milestone, effective in certain infections that are respiratory tract infection, urinary tract infection, bone disorders, meningococcal and mycobacterial infections, sexually transmitted diseases, skin infections, etc. Fluoroquinolones are first entirely man-made antibiotics that exhibit antibacterial activity through the inhibition of topoisomerase II, topoisomerase IV and deoxyribonucleic acid gyrase, which is vital for chromosome replication and function. The post-marketing surveillance pointed out the favorable side effects associated with fluoroquinolones such as phototoxicity, QT interval prolongation and anaphylaxis. The discovery, development and clinical use of fluoroquinolone antibiotics in the last century contributed to a decline in morbidity and mortality rates.

The antimicrobial potential and pharmacokinetic profiles of novel quinoline-based scaffolds: synthesis and in silico mechanistic studies as dual DNA gyrase and DHFR inhibitors

The resistance of pathogenic microbes to currently available antimicrobial agents has been considered a global alarming concern.

Meningitis in a Chinese adult patient caused by Mycoplasma hominis: a rare infection and literature review

Background

Mycoplasma hominis, a well known cause of neonatal infection, has been reported as a pathogen in urogenital infections in adults; however, central nervous system (CNS) infections are rare. We report here the first case of M. hominis meningitis in China, post neurosurgical treatment for an intracerebral haemorrhage in a 71-year-old male.

Case presentation

We describe a 71-year-old man who developed M. hominis meningitis after neurosurgical treatment and was successfully treated with combined azithromycin and minocycline therapy of 2 weeks duration, despite delayed treatment because the Gram stain of cerebrospinal fluid (CSF) yielded no visible organisms. The diagnosis required 16S rDNA sequencing analysis of the cultured isolate from CSF. Literature review of M. hominis CNS infections yielded 19 cases (13 instances of brain abscess, 3 of meningitis, 1 spinal cord abscess and 1 subdural empyema each). Delay in diagnosis and initial treatment failure was evident in all cases. With appropriate microbiological testing, antibiotic therapy (ranging from 5 days to 12 weeks) and often, multiple surgical interventions, almost all the patients improved immediately.

Conclusions

Both our patient findings and the literature review, highlighted the pathogenic potential of M. hominis together with the challenges prompted by rare infectious diseases in particular for developing countries laboratories with limited diagnostic resources.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1885-4) contains supplementary material, which is available to authorized users.

Appropriate use of fluoroquinolones in children

With the increasing resistance to antibiotics among common bacterial pathogens, challenges associated with the use of fluoroquinolones (FQs) in paediatrics have emerged. The majority of FQs have favourable pharmacokinetic properties, although these properties can differ in children compared with adults. Moreover, all FQs have broad antimicrobial activity both against Gram-positive and Gram-negative bacteria. However, only some FQs for which adequate studies are available have been approved for use in children in a limited number of clinical situations owing to the supposed risk of development of severe musculoskeletal disorders, as demonstrated in juvenile animals. Recent short- and long-term evaluations appear to indicate that, at least for levofloxacin, this risk, if present at all, is marginal. This marginal risk could lead to more frequent use of FQs in children, even to treat diseases for which several other drugs with documented efficacy, safety and tolerability are considered the first-line antibiotics. However, for most of the FQs, adequate long-term studies of safety are not available. This indicates that the use of FQs should be limited to selected respiratory infections (including tuberculosis), exacerbation of lung disease in cystic fibrosis, central nervous system infections, enteric infections, febrile neutropenia, as well as serious infections attributable to FQ-susceptible pathogen(s) in children with life-threatening allergies to alternative agents. When considering diseases that could benefit from the use of FQs, particular attention must be paid to the choice of drug and its dosage, considering that not all of the FQs have been evaluated in different diseases.

Bacterial meningitis: epidemiology, pathogenesis and management update

Bacterial meningitis continues to be an important disease throughout the world and can be a life-threatening emergency if not suspected, appropriately diagnosed and managed expeditiously. The epidemiology of bacterial meningitis has changed dramatically over the last 20 years, primarily as a result of the introduction of conjugate vaccines against the common meningeal pathogens, such that in the developed world where vaccination is routinely utilized, bacterial meningitis has become a disease of adults rather than of infants and children. The management approach to patients with suspected or proven bacterial meningitis includes emergent cerebrospinal fluid analysis and initiation of appropriate antimicrobial and adjunctive therapies. The choice of empirical antimicrobial therapy is based on the patient's age and underlying disease status; once the infecting pathogen is isolated, antimicrobial therapy can be modified for optimal treatment. Many patients with suspected or proven bacterial meningitis should also receive adjunctive dexamethasone therapy. This is based on experimental animal model data which demonstrated that the subarachnoid space inflammatory response that results from antimicrobial-induced bacterial lysis can contribute to morbidity and mortality. Clinical studies have demonstrated the benefit of adjunctive dexamethasone in infants and children with Haemophilus influenzae type B meningitis, and adults with pneumococcal meningitis, in which mortality and adverse outcome are reduced. Use of adjunctive dexamethasone in adults with meningitis caused by other bacteria, and in infants and children with pneumococcal meningitis, is controversial. To be effective, adjunctive dexamethasone should be administered concomitant with or just prior to the first antimicrobial dose for maximal effect on the subarachnoid space inflammatory response.

[Treatment of community acquired bacterial meningitis, after microbiological identification]

INTRODUCTION

Are the 1996 SPILF consensus conference recommendations on bacterial meningitis (BM) still adequate?

OBJECTIVE

The literature published after 1996 was analyzed and the reviewers summarized the available data on antibiotic treatment once BM microbiological diagnosis made or strongly suspected.

METHOD

A review was made using PubMed, 10,015 references were examined. Only articles published after 1997 were analyzed.

RESULTS

No study allowed to recommend other regimens than those previously recommended in 1996, in case of meningococcal or pneumococcal infection: 3rd generation cephalosporin or amoxicillin, combined with vancomycin in case of penicillin-intermediate or resistant pneumococcus. In some cases, alternatives are possible, in case of pneumococcal infection: meropenem or antipneumococcal fluoroquinolone were recommended by US guidelines. New antibiotics available on the market were tested using experimental pneumococcal meningitis models: daptomycin and ertapenem seemed to be useful but linezolid was not. Among the antibiotic combinations tested, ceftriaxone+rifampicine demonstrated a better efficacy than ceftriaxone+vancomycin. There was not contributive published data on the length of treatment for bacterial meningitis.

CONCLUSION

No assessed arguments could be found to modify previous guidelines. In case of problem with penicillin-resistant pneumococci, penem or a combination using ceftriaxone and rifampicin may be used.

Successful treatment of post-neurosurgical intracranial Mycoplasma hominis infection using gatifloxacin

We describe two cases of intracerebral infection with Mycoplasma hominis following neurosurgery, the first after removal of a colloid cyst, the other after a craniotomy following a motor vehicle accident (MVA). Both infections were successfully treated with parenteral gatifloxacin, with ongoing clindamycin or moxifloxacin for associated osteomyelitis.

INTRAVITREAL TOXICITY OF GARENOXACIN

PURPOSE

To assess the retinal toxicity of varying concentrations of intravitreally injected garenoxacin.

METHODS

Twenty eyes of 20 New Zealand albino rabbits were used for this study. The animals were anesthetized with ketamine (35-50 mg/kg) and xylazine (3-5 mg/kg). Garenoxacin was titrated using distilled water to the following concentrations: 4,000, 2,000, 1,000, 400, 200, and 100 microg/0.1 mL. Each concentration was injected intravitreally (0.1 mL) into three rabbit eyes. Three control eyes were injected with 0.1 mL of balanced saline solution. All animals were examined before and after injection by indirect ophthalmoscopy and slit-lamp biomicroscopy. Electroretinography was performed on all animals before intravitreal injection and 14 days after injection. The animals were examined by indirect ophthalmoscopy and slit-lamp biomicroscopy before they were killed; the eyes were enucleated and examined with light microscopy.

RESULTS

No electroretinographic changes or signs of retinal toxicity by slit-lamp examination, indirect ophthalmoscopy, or light microscopy were seen in any eyes 14 days after intravitreal injection of garenoxacin (< or =4,000 microg/0.1 mL).

CONCLUSIONS

Garenoxacin injected intravitreally appeared safe at concentrations of < or =4,000 microg/0.1 mL.

Quinolones in 2005: an update

Quinolones are one of the largest classes of antimicrobial agents used worldwide. This review considers the quinolones that are available currently and used widely in Europe (norfoxacin, ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin) within their historical perspective, while trying to position them in the context of recent and possible future advances based on an understanding of: (1) their chemical structures and how these impact on activity and toxicity; (2) resistance mechanisms (mutations in target genes, efflux pumps); (3) their pharmacodynamic properties (AUC/MIC and Cmax/MIC ratios; mutant prevention concentration and mutant selection window); and (4) epidemiological considerations (risk of emergence of resistance, clonal spread). Their main indications are examined in relation to their advantages and drawbacks. Overall, it is concluded that these important agents should be used in an educated fashion, based on a careful balance between their ease of use and efficacy vs. the risk of emerging resistance and toxicity. However, there is now substantial evidence to support use of the most potent drug at the appropriate dose whenever this is required.

Management of anthrax meningitis

Meningitis due to infection with Bacillus anthracis is considered an infrequent manifestation of the disease but one associated with high mortality. The bioterrorism event in the USA in the autumn of 2001 demonstrated our need for a better understanding of anthrax meningitis, as well as management and antimicrobial therapy. However, human clinical trials are not possible and animal experiments to guide such therapy are limited. An approach to the treatment of anthrax meningitis, based on the pathogenicity of B anthracis, the pharmacokinetics and pharmacodynamics of individual antimicrobial agents, studies of anthrax post-exposure prophylaxis in non-human primates, experience with antimicrobial susceptibility patterns of the 2001 outbreak strain, and the clinical experience with inhalational anthrax cases during the 2001 outbreak is presented. These outbreak data, the failure of previous single-drug regimens, the concerns of resistance, and the need for coverage for other causes of bacterial mengingitis suggest initial treatment of suspected anthrax meningitis should anchor on an intravenous fluoroquinolone and should include one or two other agents with activity against B anthracis and good penetration into the central nervous system. Such other agents include penicillin, ampicillin, meropenem, vancomycin, and rifampicin.

New therapies for pneumococcal meningitis

The treatment of pneumococcal meningitis remains a major challenge, as reflected by the continued high morbidity and case fatality of the disease. The worldwide increase of penicillin-resistant pneumococci and more recently cephalosporin- and vancomycin-tolerant pneumococci has jeopardised the efficacy of standard treatments based on extended spectrum cephalosporins alone or in combination with vancomycin. This review provides a summary of newly developed antibiotics tested in the rabbit meningitis model. In particular, newer beta-lactam monotherapies (cefepime, meropenem, ertapenem), recently developed quinolones (garenoxacin, gemifloxacin, gatifloxacin, moxifloxacin) and a lipopeptide antibiotic (daptomycin) are discussed. A special emphasis is placed on the potential role of combination treatments with some of the new compounds, which are of interest based on the background of increasing resistance problems due to their often synergistic activity in the rabbit model of pneumococcal meningitis.