Bacterial Abscess Research Articles

Neuroinflammation alters voltage-dependent conductance in striatal astrocytes

Neuroinflammation has the capacity to alter normal central nervous system (CNS) homeostasis and function. The objective of the present study was to examine the effects of an inflammatory milieu on the electrophysiological properties of striatal astrocyte subpopulations with a mouse bacterial brain abscess model. Whole cell patch-clamp recordings were performed in striatal glial fibrillary acidic protein (GFAP)-green fluorescent protein (GFP)(+) astrocytes neighboring abscesses at postinfection days 3 or 7 in adult mice. Cell input conductance (G(i)) measurements spanning a membrane potential (V(m)) surrounding resting membrane potential (RMP) revealed two prevalent astrocyte subsets. A1 and A2 astrocytes were identified by negative and positive G(i) increments vs. V(m), respectively. A1 and A2 astrocytes displayed significantly different RMP, G(i), and cell membrane capacitance that were influenced by both time after bacterial exposure and astrocyte proximity to the inflammatory site. Specifically, the percentage of A1 astrocytes was decreased immediately surrounding the inflammatory lesion, whereas A2 cells were increased. These changes were particularly evident at postinfection day 7, revealing increased cell numbers with an outward current component. Furthermore, RMP was inversely modified in A1 and A2 astrocytes during neuroinflammation, and resting G(i) was increased from 21 to 30 nS in the latter. In contrast, gap junction communication was significantly decreased in all astrocyte populations associated with inflamed tissues. Collectively, these findings demonstrate the heterogeneity of striatal astrocyte populations, which experience distinct electrophysiological modifications in response to CNS inflammation.

Focal Infection Treatment using Laser‐Mediated Heating of Injectable Silk Hydrogels with Gold Nanoparticles

Medical treatment of subcutaneous bacterial abscesses usually involves systemic high-dose antibiotics and incision-drainage of the wound. Such an approach suffers from two main deficiencies: bacterial resistance to antibiotics and pain associated with multiple incision-drainage-wound packing procedures. Furthermore, the efficacy of high-dose systemic antibiotics is limited because of the inability to penetrate into the abscess. To address these obstacles, we present a treatment relying on laser-induced heating of gold nanoparticles embedded in an injectable silk-protein hydrogel. Although bactericidal nanoparticle systems have been previously employed based on silver and nitric oxide, they have limitations regarding customization and safety. The method we propose is safe and uses biocompatible, highly tunable materials: an injectable silk hydrogel and Au nanoparticles, which are effective absorbers at low laser powers such as those provided by hand held devices. We demonstrate that a single 10-minute laser treatment of a subcutaneous infection in mice preserves the general tissue architecture, while achieving a bactericidal effect - even resulting in complete eradication in some cases. The unique materials platform presented here can provide the basis for an alternative treatment of focal infections.

The choice of surgical treatment method of patients with bacterial liver abscesses

Aim. To improve the results of surgical treatment of patients with bacterial abscesses of the liver. Methods. During the period from 2000 to 2010 treated were 118 patients with bacterial liver abscesses, 75 men and 43 women aged from 18 to 80 years (mean age 52.1 years). Management of the patients was based on the developed algorithm of diagnosis and treatment of liver abscesses. Two groups of patients were formed: the main group (treatment consisted of percutaneous puncture and drainage of the abscesses under ultrasound guidance) - 94 patients, the comparison group - 24 patients. In the comparison group surgical interventions were performed using the transabdominal access: laparotomy, opening and drainage of the abscess (18 patients), hepatic resection (3 patients), left-sided hemihepatectomy (2 patients), right-sided hemihepatectomy (1 patient). Results. In the patients of the comparison group the following early postoperative complications developed: wound infection - 4, intra-abdominal hemorrhage - 1, bile leakage - 1, abscesses of the abdominal cavity - 2, exudative pleuritis - 2, pneumonia - 3 cases. The average duration of patient hospitalization was 19.5±1.6 bed-days. In the main group the average duration of patient hospitalization was 9.2±±0.6 bed-days. Early postoperative complications in patients of the main group included: intra-abdominal hemorrhage - 1, bile leakage - 1, abscesses of the abdominal cavity - 1, exudative pleuritis - 2, pneumonia - 2 cases. There were no deaths in either of the groups. Conclusion. Puncture and drainage of bacterial liver abscesses under ultrasound guidance is an effective method of treatment that makes it possible to reduce the number of abdominal operations, reduce the number of postoperative complications and shorten the hospital stay.

The phenotype of human STK4 deficiency

We describe a novel clinical phenotype associating T- and B-cell lymphopenia, intermittent neutropenia, and atrial septal defects in 3 members of a consanguineous kindred. Their clinical histories included recurrent bacterial infections, viral infections, mucocutaneous candidiasis, cutaneous warts, and skin abscesses. Homozygosity mapping and candidate gene sequencing revealed a homozygous premature termination mutation in the gene STK4 (serine threonine kinase 4, formerly having the symbol MST1). STK4 is the human ortholog of Drosophila Hippo, the central constituent of a highly conserved pathway controlling cell growth and apoptosis. STK4-deficient lymphocytes and neutrophils exhibit enhanced loss of mitochondrial membrane potential and increased susceptibility to apoptosis. STK4 deficiency is a novel human primary immunodeficiency syndrome.

Temperature management in central nervous infection

Temperature management in central nervous infection

Visualization of inflammation using 19F‐magnetic resonance imaging and perfluorocarbons

Inflammation plays a central pathophysiological role in a large number of diseases. While conventional magnetic resonance imaging (MRI) can depict gross tissue alterations due to proton changes, specific visualization of inflammation is an unmet task in clinical medicine. (19) F/(1) H MRI is a novel technology that allows tracking of stem and immune cells in experimental disease models after labelling with perfluorocarbon (PFC) emulsions. (19) F markers such as PFC compounds provide a unique signal in vivo due to the negligible (19) F background signal of the body. Concomitant acquisition of (1) H images places the labelled cells into their anatomical context. This novel imaging technique has been applied to monitor immune cell responses in myocardial infarction, pneumonia, bacterial abscess formation, peripheral nerve injury, and rejection of donor organs after transplantation. Upon systemic application PFC nanoparticles are preferentially phagozytosed by circulating monocytes/macrophages and, thus, the fluorine signal in inflamed organs mainly reflects macrophage infiltration. Moreover, attenuation of the inflammatory response after immunosuppressive or antibiotic treatments could be depicted based on (19) F/(1) H-MRI. Compared to other organ systems (19) F-MRI of neuroinflammation is still challenging, mainly because of lack in sensitivity. In focal cerebral ischemia early application of PFCs revealed ongoing thrombotic vessel occlusion rather than cell migration indicating that timing of contrast agent application is critical. Current restrictions of (19) F/(1) H-MRI in sensitivity may be overcome by improved imaging hardware, imaging sequences and reconstruction techniques, as well as improved label development and cell labelling procedures in the future.

IL-1RI (Interleukin-1 Receptor Type I) Signalling is Essential for Host Defence and Hemichannel Activity During Acute Central Nervous System Bacterial Infection

Staphylococcus aureus is a common aetiological agent of bacterial brain abscesses. We have previously established that a considerable IL-1 (interleukin-1) response is elicited immediately following S. aureus infection, where the cytokine can exert pleiotropic effects on glial activation and blood–brain barrier permeability. To assess the combined actions of IL-1α and IL-1β during CNS (central nervous system) infection, host defence responses were evaluated in IL-1RI (IL-1 receptor type I) KO (knockout) animals. IL-1RI KO mice were exquisitely sensitive to intracerebral S. aureus infection, as demonstrated by enhanced mortality rates and bacterial burdens within the first 24 h following pathogen exposure compared with WT (wild-type) animals. Loss of IL-1RI signalling also dampened the expression of select cytokines and chemokines, concomitant with significant reductions in neutrophil and macrophage infiltrates into the brain. In addition, the opening of astrocyte hemichannels during acute infection was shown to be dependent on IL-1RI activity. Collectively, these results demonstrate that IL-1RI signalling plays a pivotal role in the genesis of immune responses during the acute stage of brain abscess development through S. aureus containment, inflammatory mediator production, peripheral immune cell recruitment, and regulation of astrocyte hemichannel activity. Taken in the context of previous studies with MyD88 (myeloid differentiation primary response gene 88) and TLR2 (Toll-like receptor 2) KO animals, the current report advances our understanding of MyD88-dependent cascades and implicates IL-1RI signalling as a major antimicrobial effector pathway during acute brain-abscess formation.

Burkholderia pseudomallei osteomyelitis: An unusual cause of fever in a returned traveller.

A 52-year-old diabetic man presented to the Emergency Department with a history of fevers and pain in his right thigh. He had recently returned from a 10-month trip to Vietnam. A suspected bacterial abscess in the right thigh did not respond to empirical antibiotics. Subsequent investigations revealed melioidotic osteomyelitis of the femur. This case emphasises the need to consider the diagnosis of melioidosis in patients presenting with fever following travel in endemic areas.

Successful Long-Term Treatment of Cerebral Nocardiosis with Unexpectedly Low Doses of Linezolid in an Immunocompromised Patient Receiving Complex Polytherapy

Cerebral nocardiosis is a severe infection that carries the highest mortality rate among all bacterial cerebral abscesses. We report on a case in an immunocompromised patient which was successfully treated with unexpectedly low doses of linezolid. Therapeutic drug monitoring was very helpful in highlighting issues of poor compliance and of drug-drug interactions.

Clinical features of bacterial liver abscess in diabetic patients

This retrospective analysis showed that the most frequent pathogen causing bacterial liver abscess was Klebsiella pneumoniae in 138 patients.Compared with the patients without diabetes mellitus,it was found that:( 1 ) the percentage of diabetic patients having typical abdominal pain was lower ( P ＜ 0.05 ) ; ( 2 ) neutrophilic granulocytosis was more marked,but albumin and hemoglobin levels were lower in diabetic patients( P＜0.05 ) ; ( 3 )more diabetic patients were complicated with urinary tract infection and suffered from septicemia( P＜0.05 ) ; (4) the clinical course of treatment in diabetic patients was much more prolonged( P＜0.05 ). Key words: Bacterial liver abscess; Diabetes mellitus; Clinical feature

Delayed Diagnosis of Scrofuloderma Misdiagnosed as a Bacterial Abscess

An 82-year-old woman presented with a four-month history of an ulcerative plaque overlying her left neck. This lesion had developed as a subcutaneous nodule, gradually increased in size, and evolved into ulcers. Before visiting our Dermatology clinic, the patient had been diagnosed as having a bacterial abscess, but treatments with antibiotics were unsuccessful. The presence of a purulent discharge and prominent ulceration caused further confusion as bacterial abscess, and radiologic evaluation on computed tomography also led to the possibilities of secondary lesions from an abscess or malignancy. However, the characteristic appearance of her lesion allowed us to discern cutaneous tuberculosis, especially scrofuloderma. Based on clinical examinations, staining for acid-fast bacilli, and positive findings of polymerase chain reaction, a quick diagnosis of scrofuloderma was made. After that, she was treated successfully with anti-tuberculosis therapy and the ulcer healed. Our case highlights the problem of delayed diagnosis of scrofuloderma presenting as a bacterial abscess. In conclusion, having a high index of suspicion is needed to diagnose cutaneous tuberculosis correctly.

Multiple ring-enhancing lesions in the brain

Multiple ring-enhancing lesions in the brain

Neuro-intensive care of patients with acute CNS infections.

Infections in the central nervous system (CNS) are caused by a wide range of microorganisms resulting in distinct clinical syndromes including meningitis, encephalitis, and pyogenic infections, such as empyema and brain abscess. Bacterial and viral infections in the CNS can be rapidly fatal and can result in severe disability in survivors. Appropriate identification and acute management of these infections often occurs in a critical care setting and is vital to improving outcomes in this group of patients. This review of diagnosis and management of acute bacterial and viral infections in the CNS provides a general approach to patients with a suspected CNS infection and also provides a more detailed review of the diagnosis and management of patients with suspected bacterial meningitis, viral encephalitis, brain abscess, and subdural empyema.

No increase in headache after previous intracranial infections: a historical cohort study (HUNT)

Despite the absence of robust scientific evidence, it is today generally accepted that the acute headache typical for intracranial infections can develop into permanent headache complaints. This widespread concept was explored in the first, large, longitudinal, population-based study. Data on confirmed exposure to intracranial infections amongst all adult inhabitants in a geographical area during a 20-year period were assembled from hospital records. Surviving individuals were later invited to the third Nord-Trøndelag Health Survey (HUNT 3), where 39,690 (42%) of 94,194 invited inhabitants aged ≥20 years responded to a validated headache questionnaire. Using logistic regression, the 1-year prevalence of headache and its subtypes according to the diagnostic criteria of the International Headache Society was assessed and compared between those with and without previous confirmed intracranial infection. Age and sex were used as covariates. Overall, 43 participants were identified with earlier intracranial infection, whereof three had more than one infection: bacterial meningitis (n=19), lymphocytic meningitis (n=18), encephalitis (n=9), and brain abscess (n=1).The mean interval from infection to participation in HUNT 3 was 11.2 (range 1.5-19.7) years. There was no significant increase in the prevalence of headache (OR 1.10, 95% CI 0.58-2.07), its subtypes (migraine, or tension-type headache), or chronic daily headache (OR 1.85, 95% CI 0.45-7.68) amongst participants with previous intracranial infection compared with the surrounding population. This study challenges the existence of chronic post-bacterial meningitis headache and does not indicate the presence of other long-term headaches induced by intracranial infection.

The clinical characteristics, therapeutic outcome, and prognostic factors of non-tuberculous bacterial spinal epidural abscess in adults: a hospital-based study.

Nontuberculous bacterial spinal epidural abscess (SEA) is a serious infectious disease of spines. Despite proper management, SEA remains a disease of high morbidity. The epidemiological data in southern Taiwan is still lacking. We analyzed the clinical features, laboratory data, magnetic resonance imaging findings, and therapeutic results of 45 bacterial SEA patients, collected during a study period of six years (2003- 2008). The 45 adult SEA patients, 32 were men and 13 women, aged 17-81 years (mean = 62 years). Thoracic and lumbosacral spines were the most commonly affected segments. Staphylococcus aureus was the most commonly implicated pathogen, accounting for infections in 67% (29/43) of the culture-proven cases, and 41% (12/29) of the S. aureus strains were oxacillin resistant. Gram-negative pathogens were implicated in 30% (13/43) of the culture-proven cases. Of the 45 patients, 19 underwent antibiotic treatment alone and 26 underwent medical and surgical treatments. The therapeutic results showed that 28 patients had a good prognosis and 17 had a poor prognosis. The significant prognostic factors included higher age, presence of diabetes mellitus and chronic heart disease, and initial presentation of altered consciousness. S. aureus was the most commonly implicated pathogen of adult SEA, and most S. aureus strains were oxacillin resistant. A relatively high incidence of Gram-negative infection was observed in this study. The epidemiological characteristics of the implicated pathogens must receive special consideration when selecting the empirical antibiotics. Despite adequate management, many adults with bacterial SEA had a high incidence of poor prognosis.

The experiences of non-operative treatment in patients with bacterial brain abscess

AbstractAlthough treatment of brain abscess requires a combination of antimicrobials and surgical intervention for the infected foci, nonsurgical, empirical treatment is possible and efficient in selected groups of patients. A total of 31 patients were enrolled in this 22-year retrospective study. We describe our therapeutic experiences and attempt to analyze the risk factors that were predictive of therapeutic outcomes. Multiple logistic regression was used to evaluate the relationships between baseline clinical factors and therapeutic outcome during the study period. Of these 31 patients, 25 had community-acquired infections, whereas the other six had nosocomially-acquired infections. Thirteen cases (42%) had a single brain abscess and the other 18 cases (58%) had multiple brain abscesses. Furthermore, the association of bacterial meningitis and brain abscess was found in 81% (25/31) of cases. The overall case fatality rate was 48% (15/31). Significant risk factors for poor outcomes included Glasgow coma scale (GCS) at presentation, presence of septic shock and neck stiffness. In addition, each reduction of one point on the GCS increased the poor outcome rate by 28%. The findings of the study demonstrate that both a higher mortality rate (48%) and worse outcomes were found in this select group of patients. Among the significant prognostic factors, a lower mean GCS at presentation was a major determinant of poor outcome.

Neutrophil survival and c-kit+-progenitor proliferation in Staphylococcus aureus–infected skin wounds promote resolution

AbstractPolymorphonuclear neutrophils (PMNs) are critical for the formation, maintenance, and resolution of bacterial abscesses. However, the mechanisms that regulate PMN survival and proliferation during the evolution of an abscess are not well defined. Using a mouse model of Staphylococcus aureus abscess formation within a cutaneous wound, combined with real-time imaging of genetically tagged PMNs, we observed that a high bacterial burden elicited a sustained mobilization of PMNs from the bone marrow to the infected wound, where their lifespan was markedly extended. A continuous rise in wound PMN number, which was not accounted for by trafficking from the bone marrow or by prolonged survival, was correlated with the homing of c-kit+-progenitor cells from the blood to the wound, where they proliferated and formed mature PMNs. Furthermore, by blocking their recruitment with an antibody to c-kit, which severely limited the proliferation of mature PMNs in the wound and shortened mouse survival, we confirmed that progenitor cells are not only important contributors to PMN expansion in the wound, but are also functionally important for immune protection. We conclude that the abscess environment provides a niche capable of regulating PMN survival and local proliferation of bone marrow–derived c-kit+-progenitor cells.

Conjectural Mixed Motives

AB is a seventy-four-year-old man with longstanding chronic kidney disease related to diabetes. Six months ago, his kidney disease progressed, and he began hemodialysis three times weekly. Since then, he has been hospitalized five times for various problems including cardiac arrhythmias, low blood pressure, fluid overload, and pneumonia. One week ago, AB developed acute back pain; narcotics offered little relief. He was brought to the emergency room by his only son, FB, who is his primary caregiver. A scan revealed a bacterial abscess near his spine. In spite of appropriate antibiotics over three days, AB's mental state declined. He became disoriented and difficult to arouse. FB begins asking the health care team if withdrawing dialysis is now appropriate. A multidisciplinary meeting is held with FB, members of the primary care team, and palliative care specialists. During it, FB describes his father's decline since initiating hemodialysis. AB previously enjoyed odd jobs and spent significant time with his grandchildren. After beginning dialysis and his subsequent hospitalizations, he became nearly bedbound, requiring twenty-four-hour-a-day care. He moved in with FB and now has little time for his grandchildren. FB even reports that his father had himself considered stopping dialysis; he planned to discuss this soon with his primary care physician. FB has struggled with his role as primary caregiver. His father never wanted to be in a nursing home and FB respects this wish, but he has experienced difficulty with his employer, family stress, and fatigue--all of which are exacerbated by his father's occasional angry outbursts, refusals of care, and unwillingness to help. During the meeting, the committee reviews AB's living will. Written twenty years ago, it appoints his now-deceased wife as his preferred medical decision-maker if he becomes incapacitated. It also states that, if his condition becomes irreversible, he does not want heroic measures or to artificially prolong his dying process. Instead, he would prefer to "die with dignity." Citing this and his father's progressive decline, FB asks for his father to stop dialysis and be transferred to hospice. The health care team requests an ethics consultation: Does FB's caregiver burden undermine his legitimacy as surrogate decision-maker? commentary by Matthew DeCamp The situation in which AB, FB, and the health care team find themselves is not uncommon. AB, as a result of his ongoing infection, is delirious and lacks decision-making capacity. His living will uses generalities like "heroic," "irreversible," and "artificial," all amenable to multiple interpretations and offering no clear guidance. His wife is deceased. Without other legally appointed decision-makers, responsibility falls to his next-of-kin, his only son. FB assuredly feels internal discord. On the one hand, he is AB's medical decision-maker and ought to be able to make a substituted judgment--in other words, what AB "would have wanted." On the other hand, he is also AB's primary caregiver and will himself be impacted by whatever decision he makes. Tackling his apparent role conflict requires addressing both substituted judgment and caregiver burden, and more importantly, connecting the two. Substituted judgment has significant though frequently overlooked limitations. Empirical research suggests that surrogates correctly predict patients' end-of-life treatment preferences only two-thirds of the time. Further complicating things, an individual's preferences regarding medical decisions often change over time. Patients report that they would rather have a family member provide input into their decisions instead of merely "substituting" his or her own judgment, and surrogates describe incorporating their own values--what they want versus what the patient would want--into decisions for others. These findings have motivated calls to replace substituted judgment altogether. …

Clinical characteristics and therapeutic outcome of Gram-negative bacterial spinal epidural abscess in adults

Clinical characteristics and therapeutic outcome of Gram-negative bacterial spinal epidural abscess in adults

Amoebic Abscess of the Spleen and Fatal Colonic Perforation

Amoebic Abscess of the Spleen and Fatal Colonic Perforation