Pharmacokinetics and pharmacodynamics of antibiotics in central nervous system infections:

Pharmacometabolomics in TB meningitis-Understanding the pharmacokinetic, metabolic, and immune factors associated with anti-TB drug concentrations in cerebrospinal fluid

Poor penetration of many anti-tuberculosis (TB) antibiotics into the central nervous system (CNS) is thought to be a major driver of morbidity and mortality in TB meningitis (TBM). While the amount of a particular drug that crosses into the cerebrospinal fluid (CSF) varies from person to person, little is known about the host factors associated with interindividual differences in CSF concentrations of anti-TB drugs. In patients diagnosed with TBM from the country of Georgia (n = 17), we investigate the association between CSF concentrations of anti-TB antibiotics and multiple host factors including serum drug concentrations and CSF concentrations of metabolites and cytokines. We found > 2-fold differences in CSF concentrations of anti-TB antibiotics from person to person for all drugs tested including cycloserine, ethambutol, imipenem, isoniazid, levofloxacin, linezolid, moxifloxacin, pyrazinamide, and rifampin. While serum drug concentrations explained over 30% of the variation in CSF drug concentrations for cycloserine, isoniazid, linezolid, and pyrazinamide (adjusted R2 ≥ 0.3, p < 0.001 for all), there was no significant association between serum concentrations of imipenem and ethambutol and their respective CSF concentrations. CSF concentrations of carnitines were significantly associated with concentrations of ethambutol and imipenem (q < 0.05), and imipenem was the only antibiotic significantly associated with CSF cytokine concentrations. These results indicate that there is high interindividual variability in CSF drug concentrations in patients treated for TBM, which is only partially explained by differences in serum drug concentrations. With the exception of imipenem, there was no association between CSF drug concentrations and concentrations of cytokines and chemokines.

Optimizing Pyrazinamide Use: A Low-Hanging Fruit in Improving Outcomes with Tuberculous Meningitis? Narrative Review

Tuberculous meningitis (TBM) disables more than a third of its sufferers. Recent research has focused on optimizing the antitubercular regimen, mainly by increasing the dosage of rifampicin. However, pyrazinamide, with higher penetration into the central nervous system, is generally overlooked. We discuss the potential clinical impact of using pyrazinamide throughout antitubercular therapy in TBM, in contrast to only the intensive phase. This approach may improve the treatment outcomes and reduce disability in TBM. We summarize the available data regarding this approach from in vitro studies, clinical cohorts, toxicity data, and baseline resistance rates. Additionally, we discuss the two ongoing clinical trials evaluating this approach.

Penetration of linezolid and tedizolid in cerebrospinal fluid of mouse and impact of blood-brain barrier disruption

Penetration of antimicrobial treatments into the cerebrospinal fluid is essential to successfully treat infections of the central nervous system. This penetration is hindered by different barriers, including the blood-brain barrier, which is the most impermeable. However, inflammation may lead to structural alterations of these barriers, modifying their permeability. The impact of blood-brain barrier disruption on linezolid and tedizolid (antibiotics that may be alternatives to treat nosocomial meningitis) penetration in cerebrospinal fluid (CSF) remains unknown. The aim of this study is to evaluate the impact of blood brain barrier disruption on CSF penetration of linezolid and tedizolid. Female C57BI/6 J mice were used. Blood-brain barrier disruption was induced by an intraperitoneal administration of lipopolysaccharide. Linezolid (40 mg/kg) or tedizolid-phosphate (20 mg/kg) were injected intraperitoneally. All the plasma and CSF samples were analyzed with a validated UPLC-MS/MS method. Pharmacokinetic parameters were calculated using a non-compartmental approach based on the free drug concentration. The penetration ratio from the plasma into the CSF was calculated by the AUC0-8h (Area Under Curve) ratio (AUC0-8hCSF/AUC0-8hplasma). Linezolid penetration ratio was 46.5% in control group and 46.1% in lipopolysaccharide group. Concerning tedizolid, penetration ratio was 5.5% in control group and 15.5% in lipopolysaccharide group. In conclusion, CSF penetration of linezolid is not impacted by blood-brain barrier disruption, unlike tedizolid, whose penetration ratio increased.

Targeting inflammation and gut microbiota with antibacterial therapy: Implications for central nervous system health

The complex symbiotic relationship between inflammation, the gut microbiota, and the central nervous system (CNS) has become a pivotal focus of contemporary biomedical research. Inflammation, as a physiological defense mechanism, plays a dual role as both a protective and pathological factor, and is intricately associated with gut microbiota homeostasis, often termed the "second brain." The gutbrain axis (GBA) exemplifies this multifaceted interaction, where gut health exerts significantly regulatory effects on CNS functions. Antibacterial therapies represent both promising and challenging strategies for modulating inflammation and gut microbiota composition to confer CNS benefits. However, while such therapies may exert positive modulatory effects on the gut microbiota, they also carry the potential to disrupt microbial equilibrium, potentially exacerbating neurological dysfunction. Recent advances have provided critical insights into the therapeutic implications of antibacterial interventions; nevertheless, the application of these therapies in the context of CNS health warrants a judicious and evidence-based approach. As research progresses, deeper investigation into the microbial-neural interface is essential to fully realize the potential of therapies targeting inflammation and the gut microbiota for CNS health. Future efforts should focus on refining antibacterial interventions to modulate the gut microbiota while minimizing disruption to microbial balance, thereby reducing risks and enhancing efficacy in CNS-related conditions. In conclusion, despite challenges, a more comprehensive understanding of the GBA, along with precise modulation through targeted antibacterial therapies, offers significant promise for advancing CNS disorder treatment. Continued research in this area will lead to innovative interventions and improved patient outcomes.

Intrathecal Tigecycline in the Treatment of Hospital-Acquired Meningitis: A Review of Four Cases

Objectives: Carbapenem-resistant A. baumannii is a common cause of nosocomial meningitis, and it presents a challenge in terms of treatment because of limited therapeutic options. Intravenous tigecycline has been considered a potential salvage therapy against multi-drug-resistant Acinetobacter baumannii. However, its effectiveness is limited by its poor ability to cross the blood-brain barrier. As an alternative treatment option, intrathecal tigecycline has shown promise with its minimal side effects and high concentration in cerebrospinal fluid. Methods: In this report, we present a series of four cases infected with multi-drug-resistant A. baumannii following neurosurgery and treated with intrathecal tigecycline, including antimicrobial therapy. Results: The rate of successful microbiological response was 2 out of 3 cases (66%) in whom microbiological response could be tested anytime during the intrathecal therapy, whereas the 30-day survival rate after treatment completion was ¼ (25%). Conclusion: Although intrathecal tigecycline treatment has shown relative efficacy in achieving microbiological response, its impact on overall survival is still uncertain. Further studies involving larger groups of patients are necessary to evaluate the outcomes of intrathecal tigecycline therapy.

Treatment of persistent focalized Q fever: time has come for an international randomized controlled trial

Q fever is a worldwide zoonosis due to Coxiella burnetii, responsible for endocarditis and endovascular infections. Since the 1990s, the combination hydroxychloroquine + doxycycline has constituted the curative and prophylactic treatment in persistent focalized Q fever. This combination appears to have significantly reduced the treatment's duration (from 60 to 26 months), yet substantial evidence of effectiveness remains lacking. Data are mostly based on in vitro and observational studies. We conducted a literature review to assess the effectiveness of this therapy, along with potential alternatives. The proposed in vitro mechanism of action describes the inhibition of Coxiella replication by doxycycline through the restoration of its bactericidal activity (inhibited in acidic environment) by alkalinization of phagolysosome-like vacuoles with hydroxychloroquine. So far, the rarity and heterogeneous presentation of cases have made it challenging to design prospective studies with statistical power. The main studies supporting this treatment are retrospective cohorts, dating back to the 1990s-2000s. Retrospective studies from the large Dutch outbreak of Q fever (>4000 cases between 2007 and 2010) did not corroborate a clear benefit of this combination, notably in comparison with other regimens. Thus, there is still no consensus among the medical community on this issue. However insufficient the evidence, today the doxycycline + hydroxychloroquine combination remains the regimen with the largest clinical experience in the treatment of 'chronic' Q fever. Reinforcing the guidelines' level of evidence is critical. We herein propose the creation of an extensive international registry, followed by a prospective cohort or ideally a randomized controlled trial.

Neuroinflammation, neurodegeneration and alteration of spatial memory in BALB/c mice through ampicillin-induced gut dysbiosis; NOS2 and NFL involvement in a microbiota-gut-brain axis model

We aimed to investigate ampicillin (AMP) mechanisms in microbiota-gut-brain axis. We evaluated its effect on two gut and brain regions and behavioral performances. We administred AMP (1 g/l) to BALB/c mice for 21 days. Then, we analyzed body weigth change, stool consistency scoring, gut length, intestinal microbiota composition, nitric oxide synthase 2 (NOS2) expression and tissue integrity. We subsequently evaluated NOS2, GFAP, CD68 and NFL cerebral expression and spatial memory.Interestingly, our data showed gut microbiota disruption, NOS2 upregulation and tissue damage, associated to cerebral NOS2, GFAP, CD68 and NFL over-expression and behavioral alteration. Antiobiotic therapy should be prescribed with great caution.

Intraventricular or intrathecal polymyxin B for treatment of post-neurosurgical intracranial infection caused by carbapenem-resistant gram-negative bacteria: a 8-year retrospective study

PURPOSE

Post-neurosurgical intracranial infection caused by carbapenem-resistant gram-negative bacteria (CRGNB) is a life-threatening complication. This study aimed to assess the current practices and clinical outcomes of intravenous (IV) combined with intraventricular (IVT)/intrathecal (ITH) polymyxin B in treating CRGNB intracranial infection.

METHODS

A retrospective study was conducted on patients with post-neurosurgical intracranial infection due to CRGNB from January 2013 to December 2020. Clinical characteristics and treatment outcomes were collected and described. Kaplan-Meier survival and multivariate logistic regression analyses were performed.

RESULTS

The study included 114 patients, of which 72 received systemic antimicrobial therapy combined with IVT/ITH polymyxin B, and 42 received IV administration alone. Most infections were caused by carbapenem-resistant Acinetobacter baumannii (CRAB, 63.2%), followed by carbapenem-resistant Klebsiella pneumoniae (CRKP, 31.6%). Compared with the IV group, the IVT/ITH group had a higher cerebrospinal fluid (CSF) sterilization rate in 7 days (p < 0.001) and lower 30-day mortality (p = 0.032). In the IVT/ITH group, patients with CRKP infection had a higher initial fever (p = 0.014), higher incidence of bloodstream infection (p = 0.040), lower CSF sterilization in 7 days (p < 0.001), and higher 30-day mortality (p = 0.005) than those with CRAB infection. Multivariate logistic regression analysis revealed that the duration of IVT/ITH polymyxin B (p = 0.021) was independently associated with 30-day mortality.

CONCLUSIONS

Intravenous combined with IVT/ITH polymyxin B increased CSF microbiological eradication and improved clinical outcomes. CRKP intracranial infections may lead to more difficult treatment and thus warrant attention and further optimized treatment.

Comprehensive Therapeutic Approaches to Tuberculous Meningitis: Pharmacokinetics, Combined Dosing, and Advanced Intrathecal Therapies

Tuberculous meningitis (TBM) presents a critical neurologic emergency characterized by high mortality and morbidity rates, necessitating immediate therapeutic intervention, often ahead of definitive microbiological and molecular diagnoses. The primary hurdle in effective TBM treatment is the blood-brain barrier (BBB), which significantly restricts the delivery of anti-tuberculous medications to the central nervous system (CNS), leading to subtherapeutic drug levels and poor treatment outcomes. The standard regimen for initial TBM treatment frequently falls short, followed by adverse side effects, vasculitis, and hydrocephalus, driving the condition toward a refractory state. To overcome this obstacle, intrathecal (IT) sustained release of anti-TB medication emerges as a promising approach. This method enables a steady, uninterrupted, and prolonged release of medication directly into the cerebrospinal fluid (CSF), thus preventing systemic side effects by limiting drug exposure to the rest of the body. Our review diligently investigates the existing literature and treatment methodologies, aiming to highlight their shortcomings. As part of our enhanced strategy for sustained IT anti-TB delivery, we particularly seek to explore the utilization of nanoparticle-infused hydrogels containing isoniazid (INH) and rifampicin (RIF), alongside osmotic pump usage, as innovative treatments for TBM. This comprehensive review delineates an optimized framework for the management of TBM, including an integrated approach that combines pharmacokinetic insights, concomitant drug administration strategies, and the latest advancements in IT and intraventricular (IVT) therapy for CNS infections. By proposing a multifaceted treatment strategy, this analysis aims to enhance the clinical outcomes for TBM patients, highlighting the critical role of targeted drug delivery in overcoming the formidable challenges presented by the blood-brain barrier and the complex pathophysiology of TBM.

Effects of modified external ventricular drainage vs. an Ommaya reservoir in the management of hydrocephalus with intracranial infection in pediatric patients

Background

Hydrocephalus with intracranial infection (HII) may cause pathological changes in brain tissue structure and irreversible damage to the nervous system. However, intracranial infection is a contraindication to ventriculo-peritoneal (VP) shunt surgery, and the prognosis is improved by early infection control and intracranial pressure reduction. This study evaluated the safety and efficacy of the Ommaya reservoir vs. modified external ventricular drainage (M-EVD) in the management of HII in pediatric patients.

Methods

This retrospective controlled study included 45 pediatric patients with HII treated with an Ommaya reservoir (n = 24) or M-EVD (n = 21) between January 2018 and December 2022. Clinical outcomes, cerebrospinal fluid (CSF) test results, complications, and outcomes were compared between the Ommaya reservoir and M-EVD groups.

Results

No patient died during the follow-up period. The two groups were similar regarding age, sex, admission temperature, weight, preoperative serum protein and albumin concentrations, CSF analysis (white blood cell count, glucose concentration, and protein content), and clinical symptoms (P > 0.05). Both groups had significant changes in the CSF test results postoperatively compared with preoperatively (P < 0.05). In the M-EVD group, the median days for 13 children to remove the external drainage tube and receive VP shunt was 19 days. The longest drainage tube retention time was 61 days, and there was no intracranial infection or serious complication related to the drainage tube. After the placement of the Ommaya, the median time required for CSF to return to normal was 21 days, and a total of 15 patients underwent VP shunt surgery.

Conclusion

The Ommaya reservoir and M-EVD are safe and effective for pediatric patients with HII. Both methods reduce the intracranial pressure and alleviate the symptoms of hydrocephalus, although there are differences between the two methods.

Pharmacometabolomics in TB Meningitis - understanding the pharmacokinetic, metabolic, and immune factors associated with anti-TB drug concentrations in cerebrospinal fluid

Poor penetration of many anti-tuberculosis (TB) antibiotics into the central nervous system (CNS) is thought to be a major driver of morbidity and mortality in TB meningitis (TBM). While the amount of a particular drug that crosses into the cerebrospinal fluid (CSF) varies from person to person, little is known about the host factors associated with interindividual differences in CSF concentrations of anti-TB drugs. In patients diagnosed with TBM from the country of Georgia (n=17), we investigate the association between CSF concentrations of anti-TB antibiotics and multiple host factors including serum drug concentrations and CSF concentrations of metabolites and cytokines. We found >2-fold differences in CSF concentrations of anti-TB antibiotics from person to person for all drugs tested including cycloserine, ethambutol, imipenem, isoniazid, levofloxacin, linezolid, moxifloxacin pyrazinamide, and rifampin. While serum drug concentrations explained over 40% of the variation in CSF drug concentrations for cycloserine, isoniazid, linezolid, and pyrazinamide (adjusted R 2 >0.4, p<0.001 for all), there was no evidence of an association between serum concentrations of imipenem and ethambutol and their respective CSF concentrations. CSF concentrations of carnitines were significantly associated with concentrations of ethambutol and imipenem (q<0.05), and imipenem was the only antibiotic significantly associated with CSF cytokine concentrations. These results indicate that there is high interindividual variability in CSF drug concentrations in patients treated for TBM, which is only partially explained by differences in serum drug concentrations and not associated with concentrations of cytokines and chemokines in the CSF.

Intravenous Fosfomycin for Systemic Multidrug-Resistant Pseudomonas aeruginosa Infections

Human Pseudomonas infections have high morbidity and mortality rates. Pseudomonas bacteria can cause sepsis or septic shock; they produce biofilm and commonly exhibit a multidrug-resistant phenotype. The choice of antimicrobial therapy in many cases is challenging, and deep knowledge of clinical, microbiological, and pharmacological issues is required. Intravenous fosfomycin is being repurposed in a combination given its favorable pharmacokinetic/pharmacodynamic properties (a small molecule with favorable kinetic both in bloodstream infection and in deep-seated infections), antibiofilm activity, and its interesting synergistic effects with other antimicrobials. Recent literature on epidemiological, microbiological, pharmacological, and clinical data on intravenous fosfomycin therapy against Pseudomonas is herein reviewed and discussed.

Utilizing Ceftazidime/Avibactam Therapeutic Drug Monitoring in the Treatment of Neurosurgical Meningitis Caused by Difficult-to-Treat Resistant Pseudomonas aeruginosa and KPC-Producing Enterobacterales

Background

Central nervous system (CNS) infections caused by Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacterales and difficult-to-treat resistant (DTR) Pseudomonas aeruginosa represent a formidable clinical challenge. Antimicrobial regimens that efficiently penetrate the cerebrospinal fluid (CSF) and achieve sufficient concentrations associated with microbiologic and clinical cure are limited. We evaluated therapy with ceftazidime-avibactam (CAZ-AVI) in order to guide precise dosing in the treatment of CNS infections.

Methods

Therapeutic drug monitoring (TDM) was performed in 3 patients with health care-associated ventriculitis and meningitis (HAVM) using CAZ-AVI 2.5 g infused intravenously every 8 hours as standard and extended infusion. Simultaneous CSF and plasma samples were obtained throughout the dosing interval in each patient. Concentrations of CAZ and AVI were determined by liquid chromatography/mass spectrometry.

Results

Bacterial identification revealed KPC-producing Klebsiella pneumoniae (KPC-Kp), DTR Pseudomonas aeruginosa, and KPC-producing Enterobacter cloacae (KPC-Ent.c). All isolates were resistant to carbapenems. The minimum inhibitory concentrations (MICs) of CAZ-AVI were 0.25/4, 4/4, and 0.25/4 μg/mL, respectively. CAZ and AVI concentrations were determined in CSF samples ranging from 29.0 to 15.0 µg/mL (CAZ component) and 4.20 to 0.92 µg/mL (AVI component), respectively. AVI achieved concentrations ≥1 µg/mL in 11 out of 12 CSF samples collected throughout the dosing interval. Clinical and microbiologic cure were attained in all patients.

Conclusions

Postinfusion concentrations of CAZ-AVI were measured in plasma and CSF samples obtained from 3 patients with complicated CNS infections caused by antimicrobial-resistant isolates. The measured concentrations revealed that standard CAZ and AVI exposures sufficiently attained values correlating to 50% fT > MIC, which are associated with efficient bacterial killing.

Treatment and prognostic risk factors for intracranial infection after craniocerebral surgery

The objective of this study was to determine risk factors of pejorative evolution course in patients suffering from postoperative cranial infection. The data of patients who developed an intracranial infection after craniocerebral surgery in the neurosurgical intensive care unit of the First Affiliated Hospital of Nanjing Medical University in Nanjing, Jiangsu, China, from February 2018 to August 2019 were retrospectively analyzed. Logistic regression was used to analyze the factors influencing the prognosis of intracranial infection treatment. Sixty-four patients developed an infection after craniocerebral surgery, and 48 of them with negative CSF cultures received experimental anti-infectives. In 16 patients, cerebrospinal fluid culture showed pandrug-resistant pathogens, including 11 Acinetobacter baumannii (11), Klebsiella pneumoniae (3), Escherichia coli (1), and Candida glabrata (1). Nine patients received intraventricular or intrathecal injections of polymyxin B. The mean duration of infection treatment was 22.2 ± 9.9 days, and the clinical cure rate was 85.9% (55/64). Logistic multivariate regression analysis showed that inadequate CSF drainage (OR, 6.839; 95% CI, 1.130-41.383; P = 0.036) and infection with drug-resistant bacteria (OR, 24.241; 95% CI, 2.032-289.150; P = 0.012) were independent risk factors for postoperative intracranial infection. Intracranial infection with positive CSF culture and inadequate CSF drainage are factors contributing to the poor prognosis of intracranial infection. Moreover, early anti-infection treatment and adequate CSF drainage may improve patient outcomes. In particular, intraventricular or intrathecal injection of polymyxin B may be a safe and effective treatment strategy for MDR/XDR gram-negative bacilli infection.

Cerebrospinal fluid penetration of fosfomycin in patients with ventriculitis: an observational study

BACKGROUND

For treatment of ventriculitis, vancomycin and meropenem are frequently used as empiric treatment but cerebrospinal fluid (CSF) penetration is highly variable and may result in subtherapeutic concentrations. Fosfomycin has been suggested for combination antibiotic therapy, but data are sparse, so far. Therefore, we studied CSF penetration of fosfomycin in ventriculitis.

METHODS

Adult patients receiving a continuous infusion of fosfomycin (1 g/h) for the treatment of ventriculitis were included. Routine therapeutic drug monitoring (TDM) of fosfomycin in serum and CSF was performed with subsequent dose adaptions. Demographic and routine laboratory data including serum and CSF concentrations for fosfomycin were collected. Antibiotic CSF penetration ratio as well as basic pharmacokinetic parameters were investigated.

RESULTS

Seventeen patients with 43 CSF/serum pairs were included. Median fosfomycin serum concentration was 200 [159-289] mg/L and the CSF concentration 99 [66-144] mg/L. Considering only the first measurements in each patient before a possible dose adaption, serum and CSF concentrations were 209 [163-438] mg/L and 104 [65-269] mg/L. Median CSF penetration was 46 [36-59]% resulting in 98% of CSF levels above the susceptibility breakpoint of 32 mg/L.

CONCLUSION

Penetration of fosfomycin into the CSF is high, reliably leading to appropriate concentrations for the treatment of gram positive and negative bacteria. Moreover, continuous administration of fosfomycin appears to be a reasonable approach for antibiotic combination therapy in patients suffering from ventriculitis. Further studies are needed to evaluate the impact on outcome parameters.

Critical windows of early-life microbiota disruption on behaviour, neuroimmune function, and neurodevelopment

Numerous studies have emphasised the importance of the gut microbiota during early life and its role in modulating neurodevelopment and behaviour. Epidemiological studies have shown that early-life antibiotic exposure can increase an individual's risk of developing immune and metabolic diseases. Moreover, preclinical studies have shown that long-term antibiotic-induced microbial disruption in early life can have enduring effects on physiology, brain function and behaviour. However, these studies have not investigated the impact of targeted antibiotic-induced microbiota depletion during critical developmental windows and how this may be related to neurodevelopmental outcomes. Here, we addressed this gap by administering a broad-spectrum oral antibiotic cocktail (ampicillin, gentamicin, vancomycin, and imipenem) to mice during one of three putative critical windows: the postnatal (PN; P2-9), pre-weaning (PreWean; P12-18), or post-weaning (Wean; P21-27) developmental periods and assessed the effects on physiology and behaviour in later life. Our results demonstrate that targeted microbiota disruption during early life has enduring effects into adolescence on the structure and function of the caecal microbiome, especially for antibiotic exposure during the weaning period. Further, we show that microbial disruption in early life selectively alters circulating immune cells and modifies neurophysiology in adolescence, including altered myelin-related gene expression in the prefrontal cortex and altered microglial morphology in the basolateral amygdala. We also observed sex and time-dependent effects of microbiota depletion on anxiety-related behavioural outcomes in adolescence and adulthood. Antibiotic-induced microbial disruption had limited and subtle effects on social behaviour and did not have any significant effects on depressive-like behaviour, short-term working, or recognition memory. Overall, this study highlights the importance of the gut microbiota during critical windows of development and the subtle but long-term effects that microbiota-targeted perturbations can have on brain physiology and behaviour.

Pharmacokinetics of Antimicrobials in Children with Emphasis on Challenges Faced by Low and Middle Income Countries, a Clinical Review

Effective antimicrobial exposure is essential to treat infections and prevent antimicrobial resistance, both being major public health problems in low and middle income countries (LMIC). Delivery of drug concentrations to the target site is governed by dose and pharmacokinetic processes (absorption, distribution, metabolism and excretion). However, specific data on the pharmacokinetics of antimicrobials in children living in LMIC settings are scarce. Additionally, there are significant logistical constraints to therapeutic drug monitoring that further emphasize the importance of understanding pharmacokinetics and dosing in LMIC. Both malnutrition and diarrheal disease reduce the extent of enteral absorption. Multiple antiretrovirals and antimycobacterial agents, commonly used by children in low resource settings, have potential interactions with other antimicrobials. Hypoalbuminemia, which may be the result of malnutrition, nephrotic syndrome or liver failure, increases the unbound concentrations of protein bound drugs that may therefore be eliminated faster. Kidney function develops rapidly during the first years of life and different inflammatory processes commonly augment renal clearance in febrile children, potentially resulting in subtherapeutic drug concentrations if doses are not adapted. Using a narrative review approach, we outline the effects of growth, maturation and comorbidities on maturational and disease specific effects on pharmacokinetics in children in LMIC.

The Blood-Brain Barrier and Pharmacokinetic/Pharmacodynamic Optimization of Antibiotics for the Treatment of Central Nervous System Infections in Adults

Bacterial central nervous system (CNS) infections are serious and carry significant morbidity and mortality. They encompass many syndromes, the most common being meningitis, which may occur spontaneously or as a consequence of neurosurgical procedures. Many classes of antimicrobials are in clinical use for therapy of CNS infections, some with established roles and indications, others with experimental reporting based on case studies or small series. This review delves into the specifics of the commonly utilized antibacterial agents, updating their therapeutic use in CNS infections from the pharmacokinetic and pharmacodynamic perspectives, with a focus on the optimization of dosing and route of administration that have been described to achieve good clinical outcomes. We also provide a concise synopsis regarding the most focused, clinically relevant information as pertains to each class and subclass of antimicrobial therapeutics. CNS infection morbidity and mortality remain high, and aggressive management is critical in ensuring favorable patient outcomes while averting toxicity and upholding patient safety.

Pharmacotherapy alleviates pathological changes in human direct reprogrammed neuronal cell model of myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a trinucleotide repeat disorder affecting multiple organs. However, most of the research is focused on studying and treating its muscular symptoms. On the other hand, despite the significant impact of the neurological symptoms on patients’ quality of life, no drug therapy was studied due to insufficient reproducibility in DM1 brain-specific animal models. To establish DM1 neuronal model, human skin fibroblasts were directly converted into neurons by using lentivirus expressing small hairpin RNA (shRNA) against poly-pyrimidine tract binding protein (PTBP). We found faster degeneration in DM1 human induced neurons (DM1 hiNeurons) compared to control human induced neurons (ctrl hiNeurons), represented by lower viability from 10 days post viral-infection (DPI) and abnormal axonal growth at 15 DPI. Nuclear RNA foci were present in most of DM1 hiNeurons at 10 DPI. Furthermore, DM1 hiNeurons modelled aberrant splicing of MBNL1 and 2, MAPT, CSNK1D and MPRIP at 10 DPI. We tested two drugs that were shown to be effective for DM1 in non-neuronal model and found that treatment of DM1 hiNeurons with 100 nM or 200 nM actinomycin D (ACT) for 24 h resulted in more than 50% reduction in the number of RNA foci per nucleus in a dose dependent manner, with 16.5% reduction in the number of nuclei containing RNA foci at 200 nM and treatment with erythromycin at 35 μM or 65 μM for 48 h rescued mis-splicing of MBNL1 exon 5 and MBNL 2 exons 5 and 8 up to 17.5%, 10% and 8.5%, respectively. Moreover, erythromycin rescued the aberrant splicing of MAPT exon 2, CSNK1D exon 9 and MPRIP exon 9 to a maximum of 46.4%, 30.7% and 19.9%, respectively. These results prove that our model is a promising tool for detailed pathogenetic examination and novel drug screening for the nervous system.

Brain abscess in immunocompetent patients: recent findings

PURPOSE OF REVIEW

We conducted a systematic review of the literature to update findings on the epidemiology and the management of cerebral abscesses in immunocompetent patients.

RECENT FINDINGS

Observational studies suggest that the overall prognosis has improved over the last decades but mortality rates remain high. Several parameters may contribute to a better prognosis, including the identification of common risk factors for brain abscess, the systematic use of brain MRI at diagnosis, the implementation of appropriate neurosurgical and microbiological techniques for diagnosis, the optimization of the antibacterial treatment based on epidemiology and pharmacokinetic/pharmacodynamic studies, and a long-term follow-up for detection of secondary complications. Outcome research on brain abscess is mainly based on observational studies. Randomized controlled trials have yet to be performed to identify clinically relevant interventions associated with improved patient-centered outcomes.

SUMMARY

Our review highlights the importance of a multidisciplinary approach to optimize brain abscess management both at the acute phase and in the long-term. Randomized controlled studies are urgently needed to identify interventions associated with improved outcomes.

UPLC-MS/MS Method for Simultaneous Determination of 14 Antimicrobials in Human Plasma and Cerebrospinal Fluid: Application to Therapeutic Drug Monitoring

Pharmacokinetics/pharmacodynamics is the foundation for guiding the rational application of antibiotics in clinical practice, so it is necessary to establish quantitative methods for accurate drug concentration determination. This study aimed to develop a rapid and simple ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for simultaneous quantification of 14 antibiotics (amikacin, etimicin, ceftazidime, cefepime, cefoperazone, ceftriaxone, daptomycin, latamoxef, linezolid, meropenem, biapenem, ampicillin, norvancomycin, and vancomycin) in human plasma and cerebrospinal fluid. Antibiotics were chromatographically separated on a Waters ACQUITY UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) via gradient elution within 3 minutes and were monitored using positive ion fitted with multiple reaction monitoring. The lower limit of quantification was 0.05-2.0 μg·mL^-1. The method was verified according to the FDA bioanalysis method validation guidelines, which showed excellent accuracy (from 86.75% to 110.85%) and precision (from 0.46% to 10.97%). At last, this method was successfully applied to therapeutic drug monitoring in 113 patients under antibiotics treatment.

Preclinical Pharmacokinetic/Pharmacodynamic Studies and Clinical Trials in the Drug Development Process of EMA-Approved Antibacterial Agents: A Review

Development of new antibacterial agents is necessary as drug-resistant bacteria are a threat to global health. In Europe, the European Medicines Agency has been guiding this development process for more than two decades. We investigated preclinical and clinical pre-approval studies to illuminate the current authorization process with emphasis on pharmacokinetic/pharmacodynamic approaches and clinical phases. All centrally authorized systemic antibacterial and antimycobacterial drugs within the European Union were included without any time restriction. Additionally, US Food and Drug Administration-approved antibiotics of the previous 3 years, which were not yet approved by the European Medicines Agency, were included. We focused on preclinical pharmacokinetic/pharmacodynamic studies and phase II and phase III clinical trials. Furthermore, we looked at the recommended dosing regimens and approved indications. In this review, we designed tree diagrams as a new means of illustrating the development process of antibiotics to relate pharmacokinetic/pharmacodynamic phase II and III studies to approved indications. We included 23 (European Medicines Agency, 18; US Food and Drug Administration, 5) antimicrobial agents. Tetracyclines, carbapenems, and cephalosporins were the leading classes. The recommended dosing intervals were significantly shorter in time- vs exposure-dependent drugs (median 8 vs 12, p = 0.006). The majority of approved indications (i.e., acute bacterial skin and soft-tissue infection, community-acquired pneumonia, complicated intra-abdominal infection, complicated urinary tract infection, and complicated skin and soft-tissue infection) used non-inferiority trials. Phase II and III clinical trials investigating community-acquired pneumonia involved the fewest patients. Some promising drugs were marketed in recent years; the individual steps to their authorizations are illuminated. We confirmed the relevance of preclinical pharmacokinetic/pharmacodynamic studies in dosing optimization and decision making in antimicrobial drug development. Non-inferiority clinical trials predominated.

Successful Treatment of Severe Post-craniotomy Meningitis Caused by an Escherichia coli Sequence Type 410 Strain Coharboring bla NDM - 5 and bla CTX - M - 65

Intracranial infections caused by multidrug-resistant Gram-negative bacterium have led to considerable mortality due to extremely limited treatment options. Herein, we firstly reported a clinical carbapenem-resistant Escherichia coli isolate coharboring bla NDM - 5 and bla CTX - M - 65 from a patient with post-craniotomy meningitis. The carbapenem-resistant Escherichia coli strain CNEC001 belonging to Sequence Type 410 was only susceptible to amikacin and tigecycline, both of which have poor penetration through the blood-brain barrier (BBB). The bla CTX - M - 65 gene was expressed on a 135,794 bp IncY plasmid. The bla NDM - 5 gene was located on a genomic island region of an IncX3-type plasmid pNDM5-CNEC001. Based on the characteristics of the strain, we presented the successful treatment protocol of intravenous (IV) tigecycline and amikacin combined with intrathecal (ITH) amikacin in this study. Intracranial infection caused by Escherichia coli coharboring bla NDM - 5 and bla CTX - M - 65 is rare and fatal. Continuous surveillance and infection control measures for such strain need critical attention in clinical settings.

Antimicrobial use in central nervous system infections

PURPOSE OF REVIEW

Central nervous system (CNS) infections are associated with high rates of morbidity and mortality. The purpose of this review is to summarize current antimicrobial therapies, as well as, updates in the management of community-acquired meningitis and healthcare-associated meningitis and ventriculitis.

RECENT FINDINGS

Due to the increasing rates of multidrug resistant and extensively-drug resistant organisms, available antimicrobials are limited. Novel treatment options include newer systemic antimicrobials and antimicrobials that have previously limited data in the management of CNS infections. Although limited by retrospective data, intrathecal (IT) and intraventricular (IVT) routes of administration offer the opportunity for antimicrobials that conventionally have minimal cerebrospinal fluid (CSF) penetration to achieve high CSF concentrations while minimizing systemic exposure.

SUMMARY

Updates in the use of systemic, IT, and IVT antimicrobials offer promise as therapeutic options for CNS infections. Additional pharmacokinetic and prospective data are needed to confirm these findings.

Anti-infective treatment of purulent meningitis caused by carbapenem-resistant Klebsiella pneumoniae in a newborn: a case report

The widespread use of carbapenems has caused a notable spread of carbapenem-resistant Klebsiella pneumoniae (CRKP). The incidence of CRKP-associated infections is rising significantly in neonatal intensive care units (NICUs), which poses a grave challenge to clinical treatment. This paper is to highlight the drug treatment of CRKP with purulent meningitis in children and explore the safety of levofloxacin in children. We retrospectively analyzed the clinical data of combination therapy with levofloxacin and aztreonam in a newborn with purulent meningitis caused by CRKP. As clinical pharmacists, we evaluated the risks and benefits of quinolones for anti-infective treatment in newborns, helped clinicians adjust the anti-infective protocol of levofloxacin combined with aztreonam and provided pharmaceutical care throughout the course of treatment. In the end, the child had no fever, no dyspnea, and no obvious abnormalities in brain color Doppler ultrasound. The intracranial infection was finally controlled, and the child improved and was discharged, with no apparent neurological, skeletal, joint, tendon, or cardiac adverse events. For newborns with CRKP-associated purulent meningitis, fluoroquinolones combined with other drugs such as polymyxin, tigecycline, aminoglycosides, minocycline, that Klebsiella pneumoniae is susceptible to (when no safe and effective anti-infective alternatives are available) can reduce the mortality rate of newborns with purulent meningitis caused by carbapenem-resistant gram-negative bacteria. We analyzed the drug resistance mechanisms of CRKP, the selection of antibiotic agents, the safety of quinolones in children, the permeability of the blood-brain barrier to quinolones, and the selection of the quinolone dose. Personalized combination therapy improves treatment outcomes and reduces adverse reactions, especially in patients with resistant bacteria infection.

Tolerability of high-dose ceftriaxone in CNS infections: a prospective multicentre cohort study

BACKGROUND

Ceftriaxone is widely used to treat community-acquired CNS bacterial infections. French guidelines for meningitis in adults promote 75-100 mg/kg/day ceftriaxone without an upper limit for dosage, yet little is known about the pharmacology and tolerability of such regimens.

PATIENTS AND METHODS

A multicentre prospective cohort study was conducted in adult patients to assess the adverse drug reactions (ADRs) of high-dose ceftriaxone (i.e. daily dosage ≥4 g or ≥75 mg/kg) in CNS infections and to analyse their related factors. Drug causality was systematically assessed by an expert committee who reviewed the medical charts of all included patients.

RESULTS

A total of 196 patients were enrolled over a 31 month period. Median dosage and duration of ceftriaxone were 96.4 mg/kg/day (7 g/day) and 8 days, respectively. Nineteen ceftriaxone-related ADRs (mainly neurological) occurred in 17 patients (8.7%), with only one case of treatment discontinuation (biliary pseudolithiasis). In univariate analysis, older age, male gender, renal impairment and high trough ceftriaxone plasma concentration were associated with ceftriaxone-related ADRs.

CONCLUSIONS

High-dose ceftriaxone for CNS infection administered as recommended by French guidelines in adults was well tolerated overall, suggesting these recommendations could be applied and generalized. In patients with advanced age or renal insufficiency, prescription should be done with caution and therapeutic drug monitoring could be useful.

Sequential intraventricular injection of tigecycline and polymyxin B in the treatment of intracranial Acinetobacter baumannii infection after trauma: a case report and review of the literature

BACKGROUND

Intracranial infection after craniotomy is one of the most serious postoperative complications, especially multidrug-resistant (MDR) or extensively drug-resistant (XDR) bacterial meningitis, and strongly affects the prognosis of patients. Current treatment experience regarding these infections is scarce.

CASE PRESENTATION

We report a case of severe intracranial infection of XDR Acinetobacter baumannii (A. baumannii) that was treated by intravenous (IV) injection, sequential intraventricular (IVT) injection of tigecycline and polymyxin B, and other anti-infective drugs. Good results were obtained, and the patient was eventually discharged from the hospital. This case is characterized by intracranial infection.

CONCLUSIONS

The polymyxin B IV + IVT pathway is an ideal treatment strategy for XDR A. baumannii. The tigecycline IVT pathway is also a safe treatment option.

Intrathecal Antibacterial and Antifungal Therapies

Intrathecal administration of anti-infectives is indicated in central nervous system infections by multiresistant pathogens when drugs that can reach adequate cerebrospinal fluid (CSF) concentrations by systemic therapy are not available. Antibiotics that readily pass the blood-brain and blood-CSF barriers and/or that have low toxicity allowing an increase in the daily dosage should not be used for intrathecal therapy. Intrathecal therapy is accompanied by systemic treatment. Antibacterials indispensable for intrathecal therapy include aminoglycosides, colistin, daptomycin, tigecycline, and vancomycin. Limited experience suggests the utility of the antifungals amphotericin B and caspofungin. Intraventricular administration ensures distribution throughout the CSF compartment, whereas intralumbar dosing often fails to attain adequate antibiotic concentrations in the ventricles. The individual dose is determined by the estimated size of the CSF space and by the estimated clearance from CSF. For moderately lipophilic anti-infectives with a molecular weight above approximately 1,000 g/mol, as well as for hydrophilic drugs with a molecular weight above approximately 400 g/mol, one daily dose is normally adequate. The ventricular drain should be clamped for 15 to 120 min to facilitate the distribution of the anti-infective in the CSF space. Therapeutic drug monitoring of the trough levels is necessary only in cases of therapeutic failure.

Prevención y tratamiento de las infecciones del sitio operatorio en neurocirugía. Estado del arte

El manejo adecuado de las infecciones del sitio operatorio (ISO) en neurocirugía es fundamental para la disminución de la carga de morbilidad y mortalidad en estos pacientes. La sospecha y confirmación diagnóstica asociadas al aislamiento microbiológico son esenciales para asegurar el tratamiento oportuno y el adecuado gerenciamiento de antibióticos. En esta revisión se presenta de forma resumida los puntos fundamentales para la prevención y el tratamiento de infecciones del sitio operatorio en neurocirugía y se incluye un apartado sobre el uso de antibióticos intratecales/intraventriculares.

Brain abscess in pediatric age: a review

OBJECTIVE

The purpose of the paper is to examine the current state of the art about epidemiology, diagnosis, and treatment of this infection.

METHODS

A review of the literature was performed through a PubMed search of original articles, case reports, and reviews using the key words "brain abscess," "cerebral abscess," "brain infection," "intracranial suppuration," "otogenic brain abscess," "otitis complications," and "sinusitis complications."

RESULTS

Pediatric brain abscess is a rare but serious infection, often involving patients with specific risk factors and burdened by a high risk of morbidity and mortality. Brain abscess incidence and mortality decreased over the years, thanks to improved antibiotic therapy, new neurosurgical techniques, and the wide spread of vaccinations. There are no guidelines for the adequate diagnostic-therapeutic pathway in the management of brain abscesses; therefore, conflicting data emerge from the literature. In the future, multicentric prospective studies should be performed in order to obtain stronger evidences about brain abscesses management. Over the next few years, changes in epidemiology could be observed because of risk factors changes.

A case report of intraventricular and intrathecal tigecycline infusions for an extensively drug-resistant intracranial Acinetobacter baumannii infection

RATIONALE

The treatment of intracranial Acinetobacter baumannii infections is made difficult by multidrug-resistance poor drug penetration through the blood-brain barrier (BBB). Although tigecycline appears to be effective against A baumannii, it is only administered intravenously because it does not readily cross the BBB. The addition of intraventricular (IVT) or intrathecal infusions of tigecycline could revolutionize clinical therapy for intracranial A baumannii infections. However, there are few reports on the successful use of such treatments.

PATIENT CONCERNS

We report the case of a 17-year-old male who presented with high fever and neck rigidity after intracranial drainage.

DIAGNOSIS

Intracranial infection with extensively drug-resistant A baumannii after intracranial drainage.

INTERVENTIONS

On the advice of a clinical pharmacist, the patient was administered intrathecal infusions of tigecycline after treatment failure with IVT tigecycline.

OUTCOMES

The patient's body temperature returned to normal. Thereafter, the patient was in good clinical condition without signs of cerebrospinal fluid infection and tuberculosis.

LESSONS

However, when central nervous system infections fail IVT tigecycline, clinicians should consider changing to intrathecal tigecycline infusions rather than raising the dose of IVT tigecycline. In addition, the co-administration of tigecycline with other drugs that can penetrate the BBB should not be ruled out.

Cerebrospinal fluid pharmacokinetics of ceftaroline in neurosurgical patients with an external ventricular drain

BACKGROUND

Owing to its antibacterial properties, ceftaroline could be attractive for prevention or treatment of bacterial post-neurosurgical meningitis/ventriculitis. However, few data are available concerning its meningeal concentrations.

OBJECTIVES

To investigate ceftaroline CSF pharmacokinetics in ICU patients with an external ventricular drain (EVD).

METHODS

Patients received a single 600 mg dose of ceftaroline as a 1 h intravenous infusion. Blood and CSF samples were collected before and 0.5, 1, 3, 6, 12 and 24 h after the end of the infusion. Concentrations were assayed in plasma and CSF by LC-MS/MS. A two-step compartmental pharmacokinetic analysis was conducted. Ceftaroline plasma data were first analysed, and thereafter plasma parameters estimated and corrected for protein binding of 20% were fixed to fit unbound CSF concentrations. In the final model, parameters for both plasma and CSF data were simultaneously estimated.

RESULTS

Nine patients with an EVD were included. The Cmax was 18.29 ± 3.33 mg/L in plasma (total concentrations) and at 0.22 ± 0.17 mg/L in CSF (unbound concentration). The model-estimated CSF input/CSF output clearance ratio was 9.4%, attesting to extensive efflux transport at the blood-CSF barrier.

CONCLUSIONS

Ceftaroline CSF concentrations are too low to ensure prophylactic protection against most pathogens with MICs between 1 and 2 mg/L, owing to its limited central distribution.