Multidrug-resistant Acinetobacter baumannii ventriculitis: successful treatment with intraventricular colistin

Effective Treatment of Acinetobacter baumannii Ventriculitis With Interventricular Colistin: A Case Report

Cerebrospinal fluid shunts are the primary treatment for hydrocephalus. However, prolonged external ventricular drain (EVD) use can lead to central nervous system (CNS) infections such as ventriculitis. In the ICU setting, nosocomial infections with gram-negative, multi-drug resistant (MDR) organisms such as Acinetobacter baumannii (AB) prevail, leading to poor outcomes. AB infections are notably challenging due to their genetic drug resistance. Colistin has been reintroduced for use against gram-negative MDR pathogens but has limitations in CNS penetration when administered intravenously. Therefore, intraventricular (IVT) or intrathecal administration of colistin is recommended to enhance its therapeutic reach within the CNS. We present a case of a 22-year-old male admitted after an electric scooter accident with head trauma and hydrocephalus. A ventriculoperitoneal (VP) shunt was inserted, complicated by a nosocomial neuroinfection. Empiric IV therapy with meropenem and vancomycin was initiated. The VP shunt culture identified AB susceptible only to colistin. Intravenous (IV) colistin was added to meropenem with no significant improvement. The addition of IVT colistin significantly improved the patient's neurological condition and reduced inflammatory markers. The patient experienced one myoclonic seizure during IVT colistin treatment, managed with antiepileptics. After multiple unrelated nosocomial complications, the patient was discharged in good condition to rehabilitation. This case suggests that IVT colistin, combined with IV administration, may be preferable over IV colistin alone. Medical staff should be informed about the correct prevention and care of EVD-associated infections.

Transcriptomic Mapping of Neurotoxicity Pathways in the Rat Brain in Response to Intraventricular Polymyxin B

Intraventricular or intrathecal administration of polymyxins are increasingly used to treat multidrug-resistant (MDR) Gram-negative bacteria caused infections in the central nervous system (CNS). However, our limited knowledge of the mechanisms underpinning polymyxin-induced neurotoxicity significantly hinders the development of safe and efficacious polymyxin dosing regimens. To this end, we conducted transcriptomic analyses of the rat brain and spinal cord 1 h following intracerebroventricular administration of polymyxin B into rat lateral ventricle at a clinically relevant dose (0.5 mg/kg). Following the treatment, 66 differentially expressed genes (DEGs) were identified in the brain transcriptome while none for the spinal cord (FDR ≤ 0.05, fold-change ≥ 1.5). DEGs were enriched in signaling pathways associated with hormones and neurotransmitters, including dopamine and (nor)epinephrine. Notably, the expression levels of Slc6a3 and Gabra6 were decreased by 20-fold and 4.3-fold, respectively, likely resulting in major perturbations of dopamine and γ-aminobutyric acid signaling in the brain. Mass spectrometry imaging of brain sections revealed a distinct pattern of polymyxin B distribution with the majority accumulating in the injection-side lateral ventricle and subsequently into third and fourth ventricles. Polymyxin B was not detectable in the left lateral ventricle or brain tissue. Electrophysiological measurements on primary cultured rat neurons revealed a large inward current and significant membrane leakage following polymyxin B treatment. Our work demonstrates, for the first time, the key CNS signaling pathways associated with polymyxin neurotoxicity. This mechanistic insight combined with pharmacokinetic/pharmacodynamic dosing strategies will help guide the design of safe and effective intraventricular/intrathecal polymyxin treatment regimens for CNS infections caused by MDR Gram-negative pathogens.

Treatment of Carbapenem-Resistant Multidrug-Resistant Gram-Negative Bacilli with Intracerebroventricular Injection of Polymyxin B: A Retrospective Study

Purpose

We evaluated the efficacy and administration time of intraventricular (IVT) polymyxin B in the treatment of carbapenem-resistant and multidrug-resistant/extensively drug-resistant (MDR/XDR) Gram-negative bacilli in central nervous system (CNS) infections and investigated prognostic factors.

Patients and Methods

This retrospective analysis comprised 41 post-surgical carbapenem-resistant CNS infections from October 2016 to October 2021. All patients were treated with effective intravenous antibiotics and IVT polymyxin B. Patient characteristics, therapeutic procedure, symptoms, cerebrospinal fluid (CSF) examination, laboratory tests, and complications were recorded. The effectiveness of IVT polymyxin B was evaluated using temperature, Glasgow Coma Scale, CSF contents, bacterial clearance rate, cure rate, and mortality. Mortality between early (7 days) and late administration of IVT polymyxin B was compared. Prognostic factors were evaluated using the pupillary light reflex and multiloculated hydrocephalus.

Results

The 41 patients acquired carbapenem-resistant MDR/XDR bacteria, including 24 Klebsiella pneumoniae, 15 Acinetobacter baumannii, 3 Pseudomonas aeruginosa, and 1 Enterobacter cloacae. The bacterial clearance rate was 32/41 (78.0%), and 9 patients (22.0%) with uncured bacterial infections died. Adverse events included 1 case of skin pigmentation. Among the 32 cured patients, 31 received a ventriculoperitoneal shunt, and 1 patient had an extraventricular drainage tube removed. Mortality in the late (>7 days) group was higher (39.1% vs 0%, P < 0.05). The group without pupillary light reflex showed a higher death rate (41.2% vs 8.3%; P < 0.05). The multiloculated hydrocephalus group had a higher mortality rate than that of the normal group (34.8% vs 5.6%, P < 0.05). All 32 cured patients were followed up for 9 to 66 months, and all survived without recurrent infections.

Conclusion

Intraventricular polymyxin B is an effective treatment for carbapenem-resistant MDR/XDR Gram-negative bacilli, with a 78% cure rate and significant mortality reduction if administered within 7 days of bacterial identification. Multiloculated hydrocephalus and the pupillary light reflex may be used as prognostic indicators of mortality.

Outcome of Using Intraventricular Plus Intravenous Polymyxin B in Post-neurosurgical Patients With Multi/Extensively Drug-Resistant Gram-Negative Bacteria-Induced Intracranial Infection

Introduction

Post-neurosurgical central nervous system (CNS) infection caused by multidrug-resistant (MDR)/extensively drug-resistant (XDR) Gram-negative bacteria remains a major clinical challenge. This study describes our experience of treating such patients with combined intraventricular (IVT) and intravenous (IV) polymyxin B administration.

Methods

This retrospective study included six patients with post-neurosurgical CNS infections of carbapenem-resistant Acinetobacter baumannii (CRAB) or carbapenem-resistant Klebsiella pneumoniae (CRKP). All patients were treated in the intensive care unit (ICU) of First Affiliated Hospital, Zhejiang University School of Medicine (Hangzhou, China) between November 2020 and November 2021, and all received IVT plus IV polymyxin B. Data including patients' characteristics, therapeutic process, symptoms, cerebrospinal fluid (CSF) examination, laboratory tests, and complications were collected.

Results

Six patients with post-neurosurgical CNS infection were enrolled in the study. The patients comprised five males and one female, and the average age was 58 years (range, 38–73 years). Four out of the six cases were CRAB-positive in CSF culture, while two cases were CRKP-positive. The mean duration of polymyxin B administration was 14 ± 5.69 days (range, 6–20 days). The average period of patients reaching CSF sterilization was 10.33 ± 3.67 days (range, 5–14 days). All six cases were cured without acute kidney injury or epilepsy.

Conclusion

IVT plus IV polymyxin B is a safe and effective treatment for post-neurosurgical patients with intracranial infection caused by MDR/XDR Gram-negative bacteria.

Quantification of Colistin in Plasma by Liquid Chromatography-Tandem Mass Spectrometry: Application to a Pharmacokinetic Study

Colistin is a polymixin antibiotic (polymixin E) that is produced by Bacillus colistinus bacteria. The aim of the present study was to develop and validate a method to quantify colistin levels in plasma using high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique and then apply it in experimental animals (rats) to investigate the pharmacokinetic profile of colistin in this species. Polymyxin B was used as an internal standard (IS) and the quantitation was carried out using ESI + interface and employing multiple reaction monitoring (MRM) mode. A mobile phase consisting of acetonitrile:water:formic acid (30:70:0.1%; v/v/v) was employed and Zorbax eclipse plus C18 (1.8 µm, 2.1 mm i.d. x 50 mm) was the optimal column for this method and utilized at a flow rate of 0.2 mL/min. The full scan mass spectra of precursor/product ions of colistin A were at m/z 585.5 > 100.8, for colistin B at m/z 578.8 > 101 and for the IS at m/z 602.8 > 101. The lower limit of quantification (LLOQ) was 0.5 µg/mL. The method demonstrated acceptable intra-run and inter-run precision and accuracy for both colistin A and colistin B. Colistin was stable when assessed for long-term stability, freeze-thaw stability and autosampler stability. However, it was not stable when stored at room temperature. The matrix effect evaluation showed minimal or no effect. Incurred sample reanalysis findings were within acceptable ranges (<20% of the nominal concentration). The pharmacokinetic parameters of colistin were investigated in rats using the present method. The developed method for colistin demonstrates that it is rapid, sensitive, specific, accurate, precise, and reliable.

Neurodevelopment Outcome of Neonates Treated With Intraventricular Colistin for Ventriculitis Caused by Multiple Drug-Resistant Pathogens-A Case Series

Background: Multiple-drug-resistant Gram-negative bacteria (MDR-GNB)-associated neonatal ventriculitis is a life-threatening complication that needs timely diagnosis and effective treatment with broad-spectrum antimicrobials in critical-care settings. Inadequate penetration of antibiotics through the blood-brain barrier also demands an intraventricular (IVT) route of administration. This study reports mortality and neurodevelopmental sequelae of neonates till 18 months of age, who received IVT-colistin for treating MDR-GNB associated ventriculitis. Methods: In a case series of seven neonates with ventriculitis due to MDR-GNB at NICU of Aga Khan University Hospital, Pakistan, between June 2015 and 2018, we reviewed IVT-colistin therapy in critically ill neonates. Treatment outcomes were assessed based on clinical sign's resolution and MDR-GNB eradication in subsequent CSF cultures. Neurodevelopmental outcomes were evaluated at 18 months after discharge. Results: The average birth weight was 1.38 kg (range: 1.02-1.5 kg), and the average gestational age was 30.7 weeks (ranged: 26-34 weeks). All neonates reported colistin-sensitive MDR-GNB in CSF, five with Acinetobacter baumannii, and polymicrobial CNS infection was found in two patients (one due to Klebsiella pneumonia and A. baumannii and one due to K. pneumonia and Escherichia coli). All neonates received IVT colistin and concomitant intravenous meropenem, and five of them also received intravenous colistin. One neonate died. At the 18-month assessment, only one neonate had cerebral palsy and hydrocephaly and 50% had seizure disorders. Conclusion: Practicing intraventricular antibiotics in the neonatal population is challenging but may be used successfully, especially to overcome the limitation of poor penetration through the blood-brain barrier.

Local complications of adjunct intrathecal antibiotics for nosocomial meningitis associated with gram-negative pathogens: a meta-analysis

Direct delivery of antibiotics to the ventricular system offers an alternative for the management of nosocomial meningitis. However, the available literature frequently results in controversial findings regarding its safety. The present meta-analysis aimed at summarizing the risk of local complications after the administration of intraventricular/intrathecal (IVT/IT) antibiotics for the treatment of ventriculitis/meningitis (VM) associated with gram-negative pathogens. We systematically searched the medical literature from 1964 until July 2018, for clinical studies reporting on complications after the index treatment. The quality of the eligible studies was classified as "high," "moderated," and "low" for randomized controlled trials, observational studies, and case series, respectively. The results were summarized as pooled frequencies, estimated by the random- or fixed-effects models, according to the inter-study heterogeneity. The publication bias was visualized in trim-and-fill funnel plots. Τhe analysis included twenty-three primary studies with 229 patients. The overall complication rate was as high as 0.13 (95% CI 0.08; 0.19, I² = 9%); chemical meningitis and seizures represented the majority of the complications, with an occurrence rate of 0.11 (95% CI 0.07; 0.17, I² = 0%) and 0.07 (95% CI 0.04; 0.12; I² = 0%), respectively. The meta-analysis was based on studies of "moderate" and "low" reporting quality, while the publication bias after inspecting of the funnel plots revealed significant asymmetry. The present review denotes the absence of large, high-quality studies in the field. Nevertheless, IVT/IT was associated with moderate morbidity, mainly attributed to chemical meningitis and seizures. Further high-quality studies are still required before this therapeutic modality becomes broadly established.

Outcome Following the Treatment of Ventriculitis Caused by Multi/Extensive Drug Resistance Gram Negative Bacilli; Acinetobacter baumannii and Klebsiella pneumonia

Introduction: CNS ventriculitis is a serious complication following an intracranial insult that demands immediate treatment with broad-spectrum antibiotics in a critical care setting. Infections due to multi/extensive drug resistance (MDR/XDR) microorganisms are very challenging, which may demand an additional approach to the ongoing practice; intravenous and intraventricular administration of antibiotics.

Aim: To study the efficacy and safety of thorough ventricular irrigation followed by daily intraventricular antibiotic administration in patients with MDR/XDR ventriculitis.

Materials and Methods: A retrospective analysis was done on 19 inpatients with ventriculitis caused by Acinetobacter baumannii (AB) or Klebsiella pneumonia (KP), at Shanghai Tenth People's Hospital from January 2016 to October 2017. We reviewed our experience; the role of thorough ventricular irrigation with Colistin mixed normal saline, followed by intraventricular Colistin therapy. Treatment outcomes were evaluated based on the clinical symptoms, Cerebro-Spinal Fluid (CSF) culture, laboratory findings and complications.

Results: A total of 19 patients were included (15 males and 4 females), with a mean age in years of 51, which ranged from 18–67. Fourteen patients had Acinetobacter baumannii (AB) and 5 had Klebsiella pneumoniae (KP). The average CSF sterilization period following ventricular irrigation and intraventricular Colistin was 6 days. Sixteen patients (84%) were cured, and 3 patients (15%) died during the course of the treatment.

Conclusion: In addition to Intraventricular Colistin, thorough ventricular irrigation could increase the cure rate up to 84% in patients suffering from MDR/XDR CNS ventriculitis.

Minocycline attenuates colistin-induced neurotoxicity via suppression of apoptosis, mitochondrial dysfunction and oxidative stress

Background

Neurotoxicity is an adverse effect patients experience during colistin therapy. The development of effective neuroprotective agents that can be co-administered during polymyxin therapy remains a priority area in antimicrobial chemotherapy. The present study investigates the neuroprotective effect of the synergistic tetracycline antibiotic minocycline against colistin-induced neurotoxicity.

Methods

The impact of minocycline pretreatment on colistin-induced apoptosis, caspase activation, oxidative stress and mitochondrial dysfunction were investigated using cultured mouse neuroblastoma-2a (N2a) and primary cortical neuronal cells.

Results

Colistin-induced neurotoxicity in mouse N2a and primary cortical cells gives rise to the generation of reactive oxygen species (ROS) and subsequent cell death via apoptosis. Pretreatment of the neuronal cells with minocycline at 5, 10 and 20 μM for 2 h prior to colistin (200 μM) exposure (24 h), had an neuroprotective effect by significantly decreasing intracellular ROS production and by upregulating the activities of the anti-ROS enzymes superoxide dismutase and catalase. Minocycline pretreatment also protected the cells from colistin-induced mitochondrial dysfunction, caspase activation and subsequent apoptosis. Immunohistochemical imaging studies revealed colistin accumulates within the dendrite projections and cell body of primary cortical neuronal cells.

Conclusions

To our knowledge, this is first study demonstrating the protective effect of minocycline on colistin-induced neurotoxicity by scavenging of ROS and suppression of apoptosis. Our study highlights that co-administration of minocycline kills two birds with one stone: in addition to its synergistic antimicrobial activity, minocycline could potentially ameliorate unwanted neurotoxicity in patients undergoing polymyxin therapy.

Active efflux pump adeB is involved in multidrug resistance of Acinetobacter baumannii induced by antibacterial agents

The aim of the present study was to investigate the resistance of Acinetobacter baumannii, which was induced by cefepime (FEP), cefoperazone-sulbactam (SCF), tazobactam (TZP), levofloxacin (LEV), amikacin (AK), imipenem (IPM), and ciprofloxacin (CIP), in vitro. Multi-step drug resistance selection of 16 A. baumannii strains was performed using seven antibacterial agents (FEP, TZP, CIP, AK, IPM, SCF, and LEV). The minimum inhibitory concentration (MIC) was determined using the agar dilution method. Random amplified polymorphic DNA polymerase chain reaction was performed to analyze the genotypes and the carrying rates of aac(3)-I, aac(6')-I, ant(3)-I, aph(3)-Via, OXA-23, OXA-24, AmpC, TEM-1, metallo-β-lactamase gene (IMP), armA, rmtA, rmtB, parC, gyrA and adeB. Expression of adeB was determined using semi-quantitative reverse transcription-polymerase chain reaction (Semi-qRT-PCR). Among the 16 strains, 15 strains with drug resistance (93.8%) were obtained following in vitro induction. Notable increases (8- to 128-fold) were noted in the MIC and different genotypes were showed in RAPD of the strains before and after performing the drug resistant test. PCR data revealed significant differences (P<0.05) between the carrying rates of resistant genes before and after drug induction, with the exception of rmtA, OXA-24, TEM-1, and IMP. Significant increases were demonstrated in the comparative adeB grayscale in strains that underwent drug induction when compared with the sensitive strains (55.69±43.11% vs. 10.08±26.35%; P=0.001). Findings of the present study suggest that the active efflux pump, adeB, has an important role in multidrug resistance of the A. baumannii induced by antibacterial agents in vitro.

Variables determining mortality in patients with Acinetobacter baumannii meningitis/ventriculitis treated with intrathecal colistin

AIM

To examine the variables associated with mortality in patients with Acinetobacter baumannii-related central nervous system infections treated with intrathecal colistin.

MATERIALS AND METHODS

This multi-centre retrospective case control study included patients from 11 centres in Turkey, as well as cases found during a literature review. Only patients with CNS infections caused by multidrug-resistant or extensively drug-resistant Acinetobacter baumannii treated with intrathecal colistin were included in this study. The variables associated with mortality were determined by dividing the patients into groups who died or survived during hospitalisation, and who died or survived from Acinetobacter meningitis.

RESULTS

Among the 77 cases enrolled in the study, 35 were found through a literature review and 42 were cases from our centres. Forty-four cases (57.1%) were male and the median age was 48 years (range: 20-78 years). Thirty-seven patients (48%) died during hospitalisation. The variables associated with increased all-cause mortality during hospitalisation included old age (odds ratio, 1.035; 95% confidence interval (CI), 1.004-1.067; p=0.026) and failure to provide cerebrospinal fluid sterilisation (odds ratio, 0.264; 95% confidence interval, 0.097-0.724; p=0.01). There is a trend (P=0.062) towards higher mortality with using of meropenem during meningitis treatment. Fifteen cases (19%) died from meningitis. There were no significant predictors of meningitis-related mortality.

CONCLUSIONS

The mortality rate for central nervous system infections caused by multidrug-resistant or extensively drug-resistant Acinetobacter baumannii is high. Old age and failure to provide CSF sterilisation are associated with increased mortality during hospitalisation.

Significance of nucleic acid testing in diagnosis and treatment of post-neurosurgical meningitis caused by multidrug-resistant Acinetobacter baumannii: a case report

Background

Neurosurgery may pose the risk of patients’ developing nosocomial meningitis caused by infection with hospital pathogens. Rapid detection of the causative pathogens is essential for selecting the appropriate antibiotic treatment. However, the classical culture-based detection of bacterial infection is time-consuming and often fails to establish the correct diagnosis. Molecular techniques offer improved diagnostic means to guide the proper antibiotic therapy.

Case presentation

A 32-year-old Vietnamese man underwent neurosurgery and subsequently developed meningitis. The classical bacterial culture method failed to detect any infectious agents, whereas polymerase chain reaction-based assays identified Acinetobacter baumannii as the causative pathogen. In addition, detection of the acquired extended-spectrum beta-lactamase gene VEB and carbapenem resistance genes NDM-1 and IMP suggested that the isolated A. baumannii strain was multidrug resistant. Upon the establishment of the correct diagnosis, an adequate treatment regimen was chosen and he recovered completely.

Conclusions

This case report demonstrates the usefulness of the molecular approach as an important addendum and alternative to culture-based diagnosis in order to detect the pathogen causative for meningitis, including the indicators for resistance.

Intrathecal injection of tigecycline in treatment of multidrug-resistant Acinetobacter baumannii meningitis: a case report

The ubiquitous Acinetobacter baumannii is an important and troublesome pathogen of nosocomial infection. Multidrug-resistant A baumannii meningitis is very difficult to treat, usually with high mortality. The disease is generally associated with craniotomy, but rarely with lumbar puncture. However, in our case, a 45-year-old male construction worker suffered multidrug-resistant A baumannii meningitis associated with lumbar puncture. The patient responded poorly to the initial treatment with an intravenous infusion of tigecycline. However, later treatment with an intrathecal injection of tigecycline (concentration 1 mg/mL) at a dose of 10 mg every 12 hours proved to be highly efficacious. Thus, intrathecal injection of tigecycline should be seriously considered as a treatment for multidrug-resistant A baumannii meningitis.

Ventriculostomies without dressings: Low infection rates but room for quality improvement

Objective

Ventriculostomies are common procedures for patients with severe neurologic insults including trauma, aneurysmal rupture, tumor, infection or following an operation. Infection secondary to a ventriculostomy, meningitis or ventriculitis, carries a high morbidity and mortality. Insertion practices and maintenance of these interventions was evaluated.

Methods

A retrospective review was completed of patients receiving ventriculostomies at a single institution from October 2007 through September 2013. Basic patient demographics, methods of insertion and presence of infection were collected and analyzed.

Results

The mean of age of patients receiving ventriculostomies was 49 years of age and the most common indications for insertion were trauma, infection and nontraumatic intracranial hemorrhage (aneurysmal subarachnoid hemorrhage (SAH), hemorrhagic stroke, arteriovenous malformation (AVM)). External ventricular drains (EVDs) were inserted after minimal hair removal at the time of procedure, tunneling following procedure and securement of EVDs with suture at exit of skin and remainder of drain stapled to scalp without additional dressing applied. The infection rate using this practice was 5.1%.

Conclusion

Ventriculostomies with minimal hair removal and no dressing have equivalent infection rates with the most recent published national average.

Intraventricular versus intravenous colistin for the treatment of extensively drug resistant Acinetobacter baumannii meningitis

BACKGROUND AND PURPOSE

Reports on the safety and efficacy of intraventricularly administered (IVT) colistin for the treatment of Acinetobacter baumannii ventriculomeningitis in adults are limited and no comparative studies of IVT colistin versus intravenous (IV) therapy alone have been published. This study compared outcomes of patients with postneurosurgical ventriculomeningitis caused by extensively drug-resistant A. baumannii treated with IV colistin or IV plus IVT colistin.

METHODS

In an 11-year period, information on 18 consecutive patients with extensively drug-resistant A. baumannii ventriculomeningitis was collected. Infection was defined on the basis of (i) isolation of A. baumannii from the cerebrospinal fluid (CSF); (ii) laboratory evidence of CSF infection; (iii) signs/symptoms of central nervous system (CNS) infection. Patients were divided into group 1 (nine patients, IV colistin alone) and group 2 (nine patients, IV plus IVT colistin).

RESULTS

Cerebrospinal fluid sterilization was documented for 12 of 18 patients (66.6%). The CSF sterilization rate was 33.3% in group 1 and 100% in group 2 (P = 0.009). The mean time to CSF sterilization was 21 days (range 8-48). Five patients died due to A. baumannii CNS infection (all in group 1), and five deaths were unrelated to A. baumannii ventriculomeningitis. Intensive care unit mean length of stay was shorter in group 2 (20.7 vs. 41.6 days, P = 0.046). Crude relative risk ratio of cumulative incidence of persistent CNS infection in group 1 versus group 2 was 13. No cases of chemical meningitis due to intrathecal colistin administration were encountered.

CONCLUSIONS

Intraventricular colistin administration is much more effective than IV therapy alone and does not seem to add further toxicity.

Intraventricular or intrathecal colistin for the treatment of central nervous system infections caused by multidrug-resistant Gram-negative bacteria

Central nervous system infections caused by Gram-negative bacteria susceptible only to colistin are rare but life-threatening and increasing in prevalence. Given the current antibiotic development pipeline it is likely that the paucity of therapeutic options will continue for the next years. Colistin is an amphipathic bactericidal antibiotic which is administered systemically as colistin methanesulfonate (also known as colistimethate sodium). Colistin methanesulfonate is the inactive prodrug, and in cerebrospinal fluid undergoes spontaneous hydrolysis to colistin (the active form with antimicrobial activity). In this review, we describe and evaluate the clinical and experimental data supporting the use of intraventricular (IVT) or intrathecal (IT) colistin against multidrug-resistant Gram-negative infections of the central nervous system, describe the permeability of the blood-brain barrier to colistin, the pharmacokinetics of colistin after IVT administration of colistin methanesulfonate, its anti-endotoxin activity, discuss the opportunity to administer colistin intraventricularly or intrathecally and the dose regimen, and provide recommendations based on the available evidence.

Dual Intraventricular Plus Systemic Antibiotic Therapy for the Treatment of Klebsiella pneumoniae Carbapenemase–Producing Klebsiella pneumoniae Ventriculitis

Objective: To report a case of Klebsiella pneumoniae carbapenemase (KPC)-producing K pneumoniae ventriculitis successfully treated with dual intraventricular plus systemic antibiotic therapy. Case Summary: A 43-year-old woman with a ventriculoperitoneal shunt was transferred from a nursing home with fever, altered mental status, and leukocytosis. She was found to have KPC-producing K pneumoniae ventriculitis. Combination intraventricular antibiotic therapy with colistin and gentamicin plus systemic colistin and amikacin led to the resolution of infection. Discussion: Utilization of intraventricular or intrathecal antibiotics has been described in the literature for multidrug resistant (MDR) Gram-negative central nervous system (CNS) infections; however, none of the cases were caused by a KPC-producing organism. Given the pathogenicity and limited treatment options for this resistant organism, we utilized intraventricular colistin 10 mg and intraventricular gentamicin 10 mg in combination with systemic colistin and amikacin. An extensive literature search revealed several case reports and case series of documented MDR Acinetobacter baumanii CNS infections successfully treated with intraventricular colistin or aminoglycoside therapy with good tolerability. Additionally, recent pharmacokinetic analyses suggest improved cerebrospinal fluid (CSF) concentrations with direct CNS antimicrobial administration in combination with systemic therapy. Although our patient’s cerebral spinal fluid cultures were cleared with dual intraventricular plus systemic therapy, she continued to deteriorate clinically because of her comorbid conditions and required hospice admission. Conclusions: This describes the first reported case of KPC-producing K pneumoniae ventriculitis microbiologically cured based on negative blood and CSF cultures with a combination of intraventricular and systemic therapy.

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.

Intraventricular and intrathecal colistin as the last therapeutic resort for the treatment of multidrug-resistant and extensively drug-resistant Acinetobacter baumannii ventriculitis and meningitis: a literature review

Acinetobacter baumannii ventriculitis/meningitis due to the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains has become a clinical entity of considerable importance in recent years. A review of the available literature regarding intraventricular (IVT) or intrathecal (ITH) administration of colistin in MDR and XDR A. baumannii ventriculitis/meningitis was conducted and a total of 83 episodes in 81 patients were identified (71 cases in adults and 10 in children and neonates). Colistin was administered via the IVT and ITH route in 52 and 22 cases, respectively, whilst in 7 cases the exact route was not identified. The median dose of local colistin was 125000 IU (10mg) with a range of 20000 IU (1.6 mg) to 500000 IU (40 mg) in adults, whilst a dose of 2000 IU/kg (0.16 mg/kg) up to 125000 IU (10mg) was used in the paediatric population. The median duration of treatment of IVT/ITH polymyxin E was 18.5 days, whilst the median time to achieve sterilisation of cerebrospinal fluid was 4 days. The rate of successful outcome was 89%, and toxicity related to treatment mainly manifested as reversible chemical ventriculitis/meningitis was reported in nine cases (11%). Nowadays, IVT and ITH colistin represents the last resort treatment of MDR and XDR A. baumannii ventriculitis/meningitis, offering a unique, rather safe and successful mode of therapy.

Decreasing ventricular infections through the use of a ventriculostomy placement bundle: experience at a single institution

Object

Ventricular infection after ventriculostomy placement carries a high mortality rate. Responding to ventriculostomy infection rates, a multidisciplinary performance improvement team was formed, a comprehensive protocol for ventriculostomy placement was developed, and the efficacy was evaluated.

Methods

A best-practice protocol was developed, including hand hygiene before the procedure; prophylactic antibiotics; sterile gloves changed between preparation, draping, and procedure; hair removal by clipping for dressing adherence; skin preparation using iodine povacrylex (0.7% available iodine) and isopropyl alcohol (74%); full body and head drape; full surgical attire for the surgeon and other bedside providers; and an antimicrobial-impregnated catheter. A checklist of critical components was used to confirm proper insertion and to monitor practice. Procedure-specific infection rates were calculated using the number of infections divided by the number of patients in whom an external ventricular drainage (EVD) device was inserted × 100 (%). Data were reported back to providers and to the committee. Bundle compliance was monitored over a 4-year period.

Results

At the authors' institution, 2928 ventriculostomies were performed between the beginning of the fourth quarter of 2006 and the end of the first quarter of 2012. Although the best-evidence bundle was applied to all patients, only 588 (20.1%) were checklist monitored (increasing from 7% to 23% over the study period). The infection rate for the 2 quarters before bundle implementation was 9.2%. During the study period, the rate decreased quarterly to 2.6% and then to 0%. Over a 4-year period, the rate was 1.06% (2007), 0.66% (2008), 0.15% (2009), and 0.34% (2010); it was 0% in 2011 and the first quarter of 2012. The overall EVD infection rate was 0.46% after bundle implementation.

Conclusions

Bundle implementation including an antimicrobial-impregnated catheter dramatically decreased EVD-related infections. Training and situational awareness of appropriate practice, assisted by the checklist, plus use of the antibiotic-impregnated catheter resulted in sustained reduction in ventriculitis.

Prolonged triple therapy for persistent multidrug-resistant Acinetobacter baumannii ventriculitis

PURPOSE

A case of persistent multidrug-resistant (MDR) Acinetobacter baumannii ventriculitis successfully treated with a prolonged and novel combination of antimicrobials is reported.

SUMMARY

A 38-year-old, 84-kg Caucasian woman with a recent history of craniotomy was admitted with nausea, fever, headache, photophobia, and drainage from her craniotomy incision. She underwent a repeat craniotomy on hospital day 4 with abscess debridement and repair of a cerebrospinal fluid leak. Cultures grew MDR A. baumannii, coagulase-negative Staphylococcus species, and methicillin-resistant Staphylococcus aureus. Based on the limited published pharmacokinetic and pharmacodynamic data for colistin, we determined a favorable outcome with i.v. colistin monotherapy was unlikely and decided to treat the patient with simultaneous i.v. and intraventricular colistin, as well as intraventricular tobramycin and i.v. rifampin. She was treated with a total of 36 days of intraventricular colistin, 40 days of intraventricular tobramycin, 51 days of i.v. colistin and rifampin, and 56 days i.v. vancomycin for infection that persisted despite multiple debridements. The patient had subsequent improvement in clinical manifestations and eradication of infection. She was subsequently discharged to an acute rehabilitation facility on hospital day 77 with posttreatment sequelae including mental impairment and renal failure requiring hemodialysis. Follow-up visits revealed significant improvement in her mental status, speech, and strength on the side not affected by the stroke.

CONCLUSION

Prolonged combination therapy with intraventricular colistin and tobramycin plus i.v. colistin, rifampin, and vancomycin led to the resolution of a persistent central nervous system infection caused by MDR A. baumannii.

Colistin in the 21st century

PURPOSE OF REVIEW

Colistin is a 50-year-old antibiotic that is being used increasingly as a 'last-line' therapy to treat infections caused by multidrug-resistant Gram-negative bacteria, when essentially no other options are available. Despite its age, or because of its age, there has been a dearth of knowledge on its pharmacological and microbiological properties. This review focuses on recent studies aimed at optimizing the clinical use of this old antibiotic.

RECENT FINDINGS

A number of factors, including the diversity in the pharmaceutical products available, have hindered the optimal use of colistin. Recent advances in understanding of the pharmacokinetics and pharmacodynamics of colistin, and the emerging knowledge on the relationship between the pharmacokinetics and pharmacodynamics, provide a solid base for optimization of dosage regimens. The potential for nephrotoxicity has been a lingering concern, but recent studies provide useful new information on the incidence, severity and reversibility of this adverse effect. Recent approaches to the use of other antibiotics in combination with colistin hold promise for increased antibacterial efficacy with less potential for emergence of resistance.

SUMMARY

Because few, if any, new antibiotics with activity against multidrug-resistant Gram-negative bacteria will be available within the next several years, it is essential that colistin is used in ways that maximize its antibacterial efficacy and minimize toxicity and development of resistance. Recent developments have improved use of colistin in the 21st century.