Infections of the central nervous system due to pseudomonas aeruginosa

Antioxidative polyphenols attenuate pyocyanin-induced ROS production in neuronal HT22 cell lines

Pyocyanin, a secreted virulence factor, plays an essential role during Pseudomonas aeruginosa infection. Infection of the central nervous system by this bacterium results in high mortality, but the studies on its mechanism are still rather limited. In this study, we first evaluate the neuronal damage caused by pyocyanin exposure in neuronal HT22 cells. Pyocyanin leads to mitochondrial syndrome and antioxidant defense disruption, therefore increasing intercellular reactive oxygen species (ROS) production. Several typical superior antioxidant polyphenols effectively protect against pyocyanin-induced neuronal cell damage. These findings suggest the neuronal protective activity more or less relies on the structure, rather than the residues. Pre-incubation of catechin activates the essential pathway, indicating inverse correlation of ERK and AMPK phosphorylation participates in this process. These data outline a novel strategy to eliminate intracellular generated ROS. The investigated candidates could be potentially used as therapeutic agents against various ROS-related neurological diseases.

Piperidine-based natural products targeting Type IV pili antivirulence: A computational approach

Type IV (T4) pilus is among the virulence factors with a key role in serious bacterial diseases. Specifically, in Neisseria meningitidis and Pseudomonas aeruginosa, it determines pathogenicity and causes infection. Here, a computational approach has been pursued to find piperidine-based inhibitor molecules against the elongation ATPase of T4 pili in these two selected pathogens. Using the modeled structures of the PilF and PilB ATPases of N. meningitidis and P. aeruginosa, virtual library screening via molecular docking has returned inhibitor molecule candidates. The dynamics of the best three binders have further been investigated in detail via molecular dynamic simulations. Among these, ligands with COCONUT IDs CNP0030078 and CNP0051517 were found to have higher potential in the inhibition of ATPases based on molecular dynamic simulation analysis and biological activity information. The obtained results will guide future efforts in antivirulence drug development against T4 pili of N. meningitidis and P. aeruginosa.

Pseudomonas aeruginosa nosocomial meningitis following spinal anesthesia – still a significant treatment dilemma

Background:

Infections of central nervous system after spinal anesthesia nowadays are a rarity; however, their presence might be of concern.

Case Description:

We report the case of lateral ventricular empyema treated unsuccessfully with parenteral antibiotic therapy, with the clinical signs of a persisting meningitis. After several lumbar taps suggesting an infection, Pseudomonas aeruginosa was isolated and a brain magnetic resonance imaging find out the collection in the left horn of the lateral ventricle. An intrathecal/intraventricular antibiotic therapy with colistin proved highly effective combined with an extra ventricular drainage to deal with the hydrocephaly.

Conclusion:

Clinicians should take into account even uncommon infectious agents while facing the picture of a meningitis otherwise nonresponsive to empiric or standard therapy.

Treatment of severe ventriculitis caused by extensively drug-resistant Acinetobacter baumannii by intraventricular lavage and administration of colistin

Background

Severe ventriculitis (SV) caused by multidrug-resistant bacteria is associated with high morbidity and mortality in neurosurgical patients. This study assessed the outcomes of patients with SV caused by Acinetobacter baumannii who were treated by intraventricular (IVT) lavage and colistin administration.

Methods

This retrospective study included consecutive patients with SV caused by A. baumannii who were admitted at the Neurosurgical Department of Shanghai Tenth People’s Hospital from January 2014 to September 2017. Patients’ medical records, radiographic images, and surgical notes were reviewed. The patients were followed up for at least 6 months after discharge.

Results

A total of 25 patients, including 20 male and five female, were enrolled in this study; the average age was 45.6 years. All patients underwent neurosurgery before infection, and all A. baumannii cultures from cerebrospinal fluid (CSF) showed extensive resistance to the tested antibiotics except for tigecycline and colistin. All the patients underwent IVT lavage followed by daily administration of colistin after surgery; 24 patients received a daily colistin dose of 100,000 IU, while one received 50,000 IU. The patients also received tigecycline-based systemic antibiotic treatment. The mean duration of IVT colistin was 13.4±2.8 days. The time required to obtain a negative CSF culture was 8.9±4.0 days. Of the 20 patients who were cured, eight underwent shunt surgery due to hydrocephalus before they were discharged to a rehabilitation center. Five patients died, including one who was re-admitted due to recurrence 1 month after discharge.

Conclusions

IVT lavage and colistin treatment may be an effective treatment for SV caused by extensively drug-resistant A. baumannii. Future studies with a larger sample size may be needed to verify the findings in this study.

Treatment ofPseudomonas aeruginosainfection in critically ill patients

Critically ill patients are on the increase in the present clinical setting. Aging of our population and increasingly aggressive medical and therapeutic interventions, including implanted foreign bodies, organ transplantation and advances in the chemotherapy of malignant diseases, have created a cohort of particularly vulnerable patients. Pseudomonas aeruginosa is one of the leading gram-negative organisms associated with nosocomial infections. This organism is frequently feared because it causes severe hospital-acquired infections, especially in immunocompromised hosts, and is often antibiotic resistant, complicating the choice of therapy. The epidemiology, microbiology, mechanisms of resistance and currently available and future treatment options for the most relevant infections caused by P. aeruginosa are reviewed.

Polymyxins revisited

The global emergence of multidrug-resistant gram-negative bacilli has spurred a renewed interest in polymyxins. Once discarded due to concerns regarding nephrotoxicity and neurotoxicity, polymyxins now hold an important role in the antibiotic armamentarium. However, more reliable information is needed to determine the optimal dosing of these agents. Also, unanswered questions regarding in vitro testing remain, including questions regarding the reliability of automated systems and the establishment of appropriate breakpoints for defining susceptibility. Most contemporary clinical studies examining the use of these agents have involved patients with infections due to multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii strains. It has been reassuring that polymyxin therapy for resistant bacteria has resulted in clinical responses and toxicity rates similar to those for carbapenem therapy for susceptible isolates. While most surveillance studies demonstrated high rates of susceptibility, several reports noted the emergence of polymyxin-resistant nosocomial pathogens. Polymyxins have assumed an important antibiotic niche for therapy for hospital-acquired infections; further studies defining the optimal use of these agents will likely extend the duration of their clinical usefulness.

Pseudomonas aeruginosa: resistance and therapeutic options at the turn of the new millennium

Pseudomonas aeruginosa is a major cause of nosocomial infections. This organism shows a remarkable capacity to resist antibiotics, either intrinsically (because of constitutive expression of beta-lactamases and efflux pumps, combined with low permeability of the outer-membrane) or following acquisition of resistance genes (e.g., genes for beta-lactamases, or enzymes inactivating aminoglycosides or modifying their target), over-expression of efflux pumps, decreased expression of porins, or mutations in quinolone targets. Worryingly, these mechanisms are often present simultaneously, thereby conferring multiresistant phenotypes. Susceptibility testing is therefore crucial in clinical practice. Empirical treatment usually involves combination therapy, selected on the basis of known local epidemiology (usually a beta-lactam plus an aminoglycoside or a fluoroquinolone). However, therapy should be simplified as soon as possible, based on susceptibility data and the patient's clinical evolution. Alternative drugs (e.g., colistin) have proven useful against multiresistant strains, but innovative therapeutic options for the future remain scarce, while attempts to develop vaccines have been unsuccessful to date. Among broad-spectrum antibiotics in development, ceftobiprole, sitafloxacin and doripenem show interesting in-vitro activity, although the first two molecules have been evaluated in clinics only against Gram-positive organisms. Doripenem has received a fast track designation from the US Food and Drug Administration for the treatment of nosocomial pneumonia. Pump inhibitors are undergoing phase I trials in cystic fibrosis patients. Therefore, selecting appropriate antibiotics and optimising their use on the basis of pharmacodynamic concepts currently remains the best way of coping with pseudomonal infections.

Intraventricular or intrathecal use of polymyxins in patients with Gram-negative meningitis: a systematic review of the available evidence

Several reports have described the use of polymyxins by the intraventricular or intrathecal route for multidrug-resistant Gram-negative meningitis. We reviewed the available clinical evidence regarding intraventricular/intrathecal administration of polymyxins in patients with meningitis, focusing on effectiveness and safety. Relevant studies were identified from PubMed (January 1950 to April 2006) as well as from the references of relevant articles. We identified 31 case reports/series that matched our inclusion criteria. Sixty-four episodes of Gram-negative meningitis (34 in adults) were reviewed. Monotherapy with polymyxins via the intraventricular or intrathecal route was used in 11 episodes and combination of systemic and local polymyxins was used in 25 episodes. In the remaining episodes, various combinations of local polymyxins with systemic and/or local antibiotics were administered. Cure was achieved in 51/64 episodes (80%); in 26/30 episodes (87%) due to Pseudomonas aeruginosa and in 10/11 episodes (91%) due to Acinetobacter spp. Toxicity related to local administration of polymyxins was noted in 17/60 (28%) patients. The most common toxicity was meningeal irritation (12 cases). Discontinuation of treatment was necessary in four episodes and dose reduction in four episodes; irreversible toxicity was not reported. The limited available evidence suggests that therapy with intraventricular/intrathecal polymyxins alone or in combination with systemic antimicrobial agents is effective against Gram-negative meningitis. Toxicity is not uncommon but it is dose-dependent and reversible. Further studies are needed to evaluate the criteria for initiation of local central nervous system treatment with polymyxins, the optimal dosages and the role of adjuvant systemic or local therapy.

Serious Infections Caused by Pseudomonas Aeruginosa

Over the last 3 decades, Pseudomonas aeruginosa has become a leading cause of infectious morbidity and mortality in certain predisposed patient populations. It primarily affects those with impaired host defenses, and its prevalence in the hospital environment makes it an important nosocomial pathogen. Infection with this organism may result in a broad spectrum of clinical manifestations, many of which may be seen in the intensive care setting. This review focuses on epidemiology, clinical presentations, nad treatment of serious Pseudomonas infections.

Hospital-acquired bacterial meningitis in neurosurgical patients

The authors review 23 cases of hospital-acquired meningitis occurring over a 15 year period in neurosurgical patients. Factors associated with the development of meningitis include recent craniotomy, cerebrospinal fluid leak, the presence of ventricular or lumbar drainage tubes, and skull fracture. Four cases were caused by Staphylococcus epidermidis; one of these patients died. In 19 cases, Gram-negative enteric bacteria were the etiologic agents, most commonly members of the Klebsiella-Enterobacter-Serratia group. Eleven of these patients died. The particular antibiotic or group of antibiotics used and the route of administration made no difference in the outcome of Gram-negative bacillary meningitis.