Instruct: Given a scientific claim, retrieve documents that support or refute the claim.
Query: Bacterial meningitis can be diagnosed on the basis of positive cerebrospinal fluid (CSF) cultures.
CONTEXT Diagnostic lumbar punctures (LPs), commonly used to rule out meningitis, are associated with adverse events. OBJECTIVE To systematically review the evidence about diagnostic LP techniques that may decrease the risk of adverse events and the evidence about test accuracy of cerebrospinal fluid (CSF) analysis in adult patients with suspected bacterial meningitis. DATA SOURCES We searched the Cochrane Library, MEDLINE (using Ovid and PubMed) from 1966 to January 2006 and EMBASE from 1980 to January 2006 without language restrictions to identify relevant studies and identified others from the bibliographies of retrieved articles. STUDY SELECTION We included randomized trials of patients aged 18 years or older undergoing interventions to facilitate a successful diagnostic LP or to potentially reduce adverse events. Studies assessing the accuracy of biochemical analysis of the CSF for possible bacterial meningitis were also identified. DATA EXTRACTION Two investigators independently appraised study quality and extracted relevant data. For studies of the LP technique, data on the intervention and the outcome were extracted. For studies of the laboratory diagnosis of bacterial meningitis, data on the reference standard and test accuracy were extracted. DATA SYNTHESIS We found 15 randomized trials. A random-effects model was used for quantitative synthesis. Five studies of 587 patients compared atraumatic needles with standard needles and found a nonsignificant decrease in the odds of headache with an atraumatic needle (absolute risk reduction [ARR], 12.3%; 95% confidence interval [CI], -1.72% to 26.2%). Reinsertion of the stylet before needle removal decreased the risk of headache (ARR, 11.3%; 95% CI, 6.50%-16.2%). The combined results from 4 studies of 717 patients showed a nonsignificant decrease in headache in patients who were mobilized after LP (ARR, 2.9%; 95% CI, -3.4 to 9.3%). Four studies on the accuracy of biochemical analysis of CSF in patients with suspected meningitis met inclusion criteria. A CSF-blood glucose ratio of 0.4 or less (likelihood ratio [LR], 18; 95% CI, 12-27]), CSF white blood cell count of 500/muL or higher (LR, 15; 95% CI, 10-22), and CSF lactate level of 31.53 mg/dL or more (> or =3.5 mmol/L; LR, 21; 95% CI, 14-32) accurately diagnosed bacterial meningitis. CONCLUSIONS These data suggest that small-gauge, atraumatic needles may decrease the risk of headache after diagnostic LP. Reinsertion of the stylet before needle removal should occur and patients do not require bed rest after the procedure. Future research should focus on evaluating interventions to optimize the success of a diagnostic LP and to enhance training in procedural skills.
To investigate the impact of the 2017 revisions of McDonald criteria on the diagnosis of multiple sclerosis (MS) in a cohort of patients with clinically isolated syndrome (CIS) and dissemination in space (DIS) of demyelinating lesions. We retrospectively analyzed 137 patients with CIS + DIS from two Italian MS centers. Application of the 2017 revisions of McDonald criteria in our cohort led to a diagnosis of MS in 82.5% of the patients who could have not been diagnosed with MS according to the previous criteria at the time of the first demyelinating event. After a follow-up of 3.8 ± 2.9 years, 85.8% of these patients eventually satisfied also the previous (2010) criteria. Application of the 2017 revisions of McDonald criteria results in an earlier diagnosis of MS in a large percentage of CIS patients destined to convert to MS.
The International Panel on MS Diagnosis presents revised diagnostic criteria for multiple sclerosis (MS). The focus remains on the objective demonstration of dissemination of lesions in both time and space. Magnetic resonance imaging is integrated with dinical and other paraclinical diagnostic methods. The revised criteria facilitate the diagnosis of MS in patients with a variety of presentations, including "monosymptomatic" disease suggestive of MS, disease with a typical relapsing-remitting course, and disease with insidious progression, without clear attacks and remissions. Previously used terms such as "clinically definite" and "probable MS" are no longer recommended. The outcome of a diagnostic evaluation is either MS, "possible MS" (for those at risk for MS, but for whom diagnostic evaluation is equivocal), or "not MS. "
Myelin-directed autoimmunity is considered to play a key role in the pathogenesis of multiple sclerosis (MS). Increased production of both pro- and anti-inflammatory cytokines is a common finding in MS. Interleukin-17 (IL-17) is a recently described cytokine produced in humans almost exclusively by activated memory T cells, which can induce the production of proinflammatory cytokines and chemokines from parenchymal cells and macrophages. In situ hybridisation with synthetic oligonucleotide probes was adopted to detect and enumerate IL-17 mRNA expressing mononuclear cells (MNC) in blood and cerebrospinal fluid (CSF) from patients with MS and control individuals. Numbers of IL-17 mRNA expressing blood MNC were higher in patients with MS and acute aseptic meningoencephalitis (AM) compared to healthy individuals. Higher numbers of IL-17 mRNA expressing blood MNC were detected in MS patients examined during clinical exacerbation compared to remission. Patients with MS had higher numbers of IL-17 mRNA expressing MNC in CSF compared to blood. This increase in numbers of IL-17 mRNA expressing MNC in CSF was not observed in patients with AM. Our results thus demonstrate increased numbers of IL-17 mRNA expressing MNC in MS with higher numbers in CSF than blood, and with the highest numbers in blood during clinical exacerbations.
OBJECTIVE Multiple sclerosis (MS) is a disease of the central nervous system with marked heterogeneity in several aspects including pathological processes. Based on infiltrating immune cells, deposition of humoral factors and loss of oligodendrocytes and/or myelin proteins, four lesion patterns have been described. Pattern II is characterized by antibody and complement deposition in addition to T-cell infiltration. MS is considered a T-cell-mediated disease, but until now the study of pathogenic T cells has encountered major challenges, most importantly the limited access of brain-infiltrating T cells. Our objective was to identify, isolate, and characterize brain-infiltrating clonally expanded T cells in pattern II MS lesions. METHODS We used next-generation sequencing to identify clonally expanded T cells in demyelinating pattern II brain autopsy lesions, subsequently isolated these as T-cell clones from autologous cerebrospinal fluid and functionally characterized them. RESULTS We identified clonally expanded CD8(+) but also CD4(+) T cells in demyelinating pattern II lesions and for the first time were able to isolate these as live T-cell clones. The functional characterization shows that T cells releasing Th2 cytokines and able to provide B cell help dominate the T-cell infiltrate in pattern II brain lesions. INTERPRETATION Our data provide the first functional evidence for a putative role of Th2/Tc2 cells in pattern II MS supporting the existence of this pathogenic phenotype and questioning the protective role that is generally ascribed to Th2 cells. Our observations are important to consider for future treatments of pattern II MS patients.
Amyotrophic Lateral Sclerosis (ALS) is a progressive degenerative  disease of the motor neurons and the cause is unknown. Diverse factors such as  genetic defects, nutritional deficiencies, head trauma, environmental toxin,  autoimmune responses and viral and bacterial infections are involved. Mycoplasmas  have been implicated as causal agents of different illnesses in human. The  purpose of this study was to investigate the presence of mycoplasmas in  the bloodstream of patients with ALS. Patients with ALS and healthy individuals  were included in the study. A blood sample was taken in tubes with or without  anticoagulant. Mycoplasmas were detected by culture or direct PCR, and the  presence of antibodies IgM and IgG against LAMPs of these microorganisms by  Western blot. Cultures for aerobic facultative bacteria were also done. Blood samples  from 13 patients and 44 healthy individuals were screened. All blood cultures  for non-fermentative mycoplasmas and aerobic facultative bacteria were  negative. Cultures for fermentative mycoplasmas were considered positive after  identification of mycoplasmal DNA by PCR. Mycoplasma sp. was detected by culture or  direct PCR in 6/13 (46%) patients and in 4/44 (9%) of healthy individuals. M. fermentans was detected by PCR using  specific primers in six patients and in two healthy individuals. IgM against  LAMPs of M. fermentans were detected  in 6/13 (46%) blood samples from patients and in 13/44 (30%) from healthy  individuals, while. IgG was detected in 4/13 (31%) patients and in 3/44 (7%)  healthy individuals. The results of this study show that mycoplasmas cause a  systemic infection and could play a role in the origin or progression of the  ALS.
Bacterial vaccines can reduce carriage rates. Colonization is usually a binary endpoint. Real time quantitative PCR (qPCR) can quantify bacterial DNA in mucosal samples over a wide range. Using culture and single-gene species-specific qPCRs for Streptococcus pneumoniae (lytA), Streptococcus pyogenes (ntpC), Moraxella catarrhalis (ompJ), Haemophilus influenzae (hdp) and Staphylococcus aureus (nuc) and standard curves against log-phase reference strain broth cultures we described frequency and peak density distributions of carriage in nasopharyngeal swabs from 161 healthy 2-4 y old children collected into STGG broth. In general, detection by qPCR and culture was consistent. Discordance mostly occurred at lower detection thresholds of both methods, although PCR assays for S. pyogenes and S. aureus were less sensitive. Density varied across 5-7 orders of magnitude for the 5 species with the abundant species skewed toward high values (modes: S. pneumoniae log3-4, M. catarrhalis & H. influenzae log4-5 CFU/ml broth). Wide ranges of bacterial DNA concentrations in healthy children carrying these bacteria could mean that different individuals at different times vary greatly in infectiousness. Understanding the host, microbial and environmental determinants of colonization density will permit more accurate prediction of vaccine effectiveness.
Micrococcus, which, when limited in its extent and activity, causes acute suppurative inflammation (phlegmon), produces, when more extensive and intense in its action on the human system, the most virulent forms of septicaemia and pyaemia.1 In an elegant series of clinical observations and laboratory studies published in 1880 and 1882, Ogston described staphylococcal disease and its role in sepsis and abscess formation.1,2 More than 100 years later, Staphylococcus aureus remains a versatile and dangerous pathogen in humans. The frequencies of both community-acquired and hospital-acquired staphylococcal infections have increased steadily, with little change in overall mortality. Treatment of these infections . . .
PURPOSE The goal of this study is to look at the geographic growth patterns of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections in our local region and to determine if specific geographic areas are at increased risk. METHODS After Institution Review Board approval (132603-3), a retrospective chart review was conducted of 614 patients who underwent incision and drainage of an abscess by a single pediatric surgical practice from January 2004 to December 2008. In addition, previously published data from 195 patients who underwent incision and drainage of an abscess from January 2000 to December 2003 were reviewed. RESULTS The most commonly cultured organism found in the pediatric population undergoing incision and drainage was S aureus (n = 388), of which 258 (66%) were methicillin resistant. This is a 21% increase from the rate of MRSA cultures identified from 2000 to 2003. Geographic information system space-time analysis showed that a cluster of 14 MRSA cases was located within a 1.44-km radius between 2000 and 2003, and 5 separate clusters of more than 20 MRSA infection cases each were identified in 3 separate cities over the 8-year time span using geographic information system spatial analysis (P value = .001). CONCLUSION Methicillin-resistant S aureus has now become the most prevalent organism isolated from cultures of community-acquired abscesses requiring incision and drainage in the pediatric population in our local region. Significant clustering of MRSA infections has appeared in several different cities within our geographic region.
CONTEXT Rates of hospital-onset methicillin-resistant Staphylococcus aureus (MRSA) infections are reported as decreasing, but recent rates of community-onset S. aureus infections are less known. OBJECTIVES To characterize the overall and annual incidence rates of community-onset and hospital-onset S. aureus bacteremia and skin and soft tissue infections (SSTIs) in a national health care system and to evaluate trends in the incidence rates of S. aureus bacteremia and SSTIs and the proportion due to MRSA. DESIGN, SETTING, AND PARTICIPANTS Observational study of all Department of Defense TRICARE beneficiaries from January 2005 through December 2010. Medical record databases were used to identify and classify all annual first-positive S. aureus blood and wound or abscess cultures as methicillin-susceptible S. aureus or MRSA, and as community-onset or hospital-onset infections (isolates collected >3 days after hospital admission). MAIN OUTCOME MEASURES Unadjusted incidence rates per 100,000 person-years of observation, the proportion of infections that was due to MRSA, and annual trends for 2005 through 2010 (examined using the Spearman rank correlation test or the Mantel-Haenszel χ2 test for linear trend). RESULTS During 56 million person-years (nonactive duty: 47 million person-years; active duty: 9 million person-years), there were 2643 blood and 80,281 wound or abscess annual first-positive S. aureus cultures. Annual incidence rates varied from 3.6 to 6.0 per 100,000 person-years for S. aureus bacteremia and 122.7 to 168.9 per 100,000 person-years for S. aureus SSTIs. The annual incidence rates for community-onset MRSA bacteremia decreased from 1.7 per 100,000 person-years (95% CI, 1.5-2.0 per 100,000 person-years) in 2005 to 1.2 per 100,000 person-years (95% CI, 0.9-1.4 per 100,000 person-years) in 2010 (P = .005 for trend). The annual incidence rates for hospital-onset MRSA bacteremia also decreased from 0.7 per 100,000 person-years (95% CI, 0.6-0.9 per 100,000 person-years) in 2005 to 0.4 per 100,000 person-years (95% CI, 0.3-0.5 per 100,000 person-years) in 2010 (P = .005 for trend). Concurrently, the proportion of community-onset SSTI due to MRSA peaked at 62% in 2006 before decreasing annually to 52% in 2010 (P < .001 for trend). CONCLUSION In the Department of Defense population consisting of men and women of all ages from across the United States, the rates of both community-onset and hospital-onset MRSA bacteremia decreased in parallel, while the proportion of community-onset SSTIs due to MRSA has more recently declined.
CD8(+) T cells are required for protective immunity against intracellular pathogens such as Listeria monocytogenes. In this study, we used class Ia MHC-deficient mice, which have a severe reduction in circulating CD8(+) T cells, to determine the protective capacity of class Ib MHC-restricted T cells during L. monocytogenes infection. The K(b-/-)D(b-/-) mutation was backcrossed onto a C.B10 (BALB/c congenic at H-2 locus with C57BL/10) background, because BALB/c mice are more susceptible to Listeria infection than other commonly studied mouse strains such as C57BL/6. C.B10 K(b-/-)D(b-/-) mice immunized with a sublethal dose of L. monocytogenes were fully protected against a subsequent lethal infection. Adoptive transfer of Listeria-immune splenocyte subsets into naive K(b-/-)D(b-/-) mice indicated that CD8(+) T cells were the major component of this protective immune response. A CD8(+) T cell line isolated from the spleen of a Listeria-infected class Ia MHC-deficient mouse was shown to specifically recognize Listeria-infected cells in vitro, as determined by IFN-gamma secretion and cytotoxicity assays. Adoptive transfer of this T cell line alone resulted in significant protection against L. monocytogenes challenge. These results suggest that even a limited number of class Ib MHC-restricted T cells are sufficient to generate the rapid recall response required for protection against secondary infection with L. monocytogenes.
The type VI secretion system (T6SS) is the most prevalent bacterial secretion system and an important virulence mechanism utilized by Gram-negative bacteria, either to target eukaryotic cells or to combat other microbes. The components show much variability, but some appear essential for the function, and two homologues, denoted VipA and VipB in Vibrio cholerae, have been identified in all T6SSs described so far. Secretion is dependent on binding of an α-helical region of VipA to VipB, and in the absence of this binding, both components are degraded within minutes and secretion is ceased. The aim of the study was to investigate if this interaction could be blocked, and we hypothesized that such inhibition would lead to abrogation of T6S. A library of 9,600 small-molecule compounds was screened for their ability to block the binding of VipA-VipB in a bacterial two-hybrid system (B2H). After excluding compounds that showed cytotoxicity toward eukaryotic cells, that inhibited growth of Vibrio, or that inhibited an unrelated B2H interaction, 34 compounds were further investigated for effects on the T6SS-dependent secretion of hemolysin-coregulated protein (Hcp) or of phospholipase A1 activity. Two compounds, KS100 and KS200, showed intermediate or strong effects in both assays. Analogues were obtained, and compounds with potent inhibitory effects in the assays and desirable physicochemical properties as predicted by in silico analysis were identified. Since the compounds specifically target a virulence mechanism without affecting bacterial replication, they have the potential to mitigate the virulence with minimal risk for development of resistance.
OBJECTIVE To determine whether myelin oligodendrocyte glycoprotein antibodies (MOG-Abs) were predictive of a demyelination phenotype in children presenting with acquired demyelinating syndrome (ADS). METHOD Sixty-five children with a first episode of ADS (12 acute disseminated encephalomyelitis, 24 optic neuritis, 18 transverse myelitis, 11 other clinically isolated syndrome) were identified from 2 national demyelination programs in the United Kingdom and France. Acute serum samples were tested for MOG-Abs by cell-based assay. Antibodies were used to predict diagnosis of multiple sclerosis (MS) at 1 year. RESULTS Twenty-three of 65 (35%) children had MOG-Abs. Antibody-positive and antibody-negative patients were not clinically different at presentation, but identification of MOG-Abs predicted a non-MS course at 1-year follow-up: only 2/23 (9%) MOG-Ab-positive patients were diagnosed with MS compared to 16/42 (38%) MOG-Ab-negative patients (p = 0.019, Fisher exact test). Antibody positivity at outset was a useful predictor for a non-MS disease course, with a positive predictive value of 91% (95% confidence interval [CI] 72-99), negative predictive value of 38% (95% CI 24-54), positive likelihood ratio of 4.02 (CI 1.0-15.4), and odds ratio of 6.5 (CI 1.3-31.3). CONCLUSIONS MOG-Abs are found at presentation in 35% of patients with childhood ADS, across a range of demyelinating disorders. Antibody positivity can be useful in predicting a non-MS disease course at onset.
OBJECTIVE To evaluate the performance of reagent test strips in screening pregnant women for asymptomatic bacteriuria at their first visit to an antenatal clinic. DESIGN Prospective case series. SETTING Antenatal clinic of a large inner city maternity hospital. SUBJECTS All women attending for their first antenatal clinic. Patients taking antibiotics for any reason and those with urinary tract symptoms were excluded. INTERVENTION A midstream urine specimen was divided; half was sent for microscopy and formal bacteriological culture and the other half was tested with a commercial reagent strip test for the presence of blood, protein, nitrite, and leucocyte esterase. MAIN OUTCOME MEASURES Sensitivity, specificity, and positive and negative predictive values of the reagent strips in diagnosing asymptomatic bacteriuria (defined as 10(5) colony forming units/ml urine). RESULTS Sensitivity was low, with a maximum of 33% when all four tests were used in combination. Specificity was high, with typical values of 99% or more. Positive predictive value reached a maximum of 69% and negative predictive value was typically 95% or more. CONCLUSION Urine reagent strips are not sufficiently sensitive to be of use in the screening for asymptomatic bacteriuria and therefore many patients would be missed. In view of the potentially serious sequelae of this condition in pregnant women we recommend that formal bacteriological investigation remain the investigation of choice in this group of patients.
Despite widespread use of antiretroviral therapies to control replication of the human immunodeficiency virus (HIV), dysfunctions of cognition that are collectively termed HIV-associated neurocognitive disorders (HAND) still occur in approximately 50% of those infected by the virus. Currently there is not a biomarker that can identify HIV-infected people who are at risk for the development of HAND. Previous studies have identified particular sphingolipid species that are dysregulated in HAND, but the neurocognitive correlates of these biochemical findings are not currently understood. To address this question, we compared cerebrospinal fluid (CSF) levels of sphingomyelin, ceramide, and sterol species with performance on standard neurological tests designed to assess the function of multiple cognitive and motor domains in HIV-infected subjects. We found that sphingomyelin:ceramide ratios for acyl chain lengths of C16∶0, C18∶0, C22∶0, and C24∶0 were associated with worse performance on several indices of memory. The most striking finding was for the acyl chain of C18∶0 that consistently associatedwith performance onmultiple tests of memory. These findings suggest that the sphingomyelin:ceramide ratio for C18∶0 may be a reasonable surrogate marker for memory dysfunction in HIV-infected subjects.
OBJECTIVES To quantify the diagnostic accuracy of selected inflammatory markers in addition to symptoms and signs for predicting pneumonia and to derive a diagnostic tool. DESIGN Diagnostic study performed between 2007 and 2010. Participants had their history taken, underwent physical examination and measurement of C reactive protein (CRP) and procalcitonin in venous blood on the day they first consulted, and underwent chest radiography within seven days. SETTING Primary care centres in 12 European countries. PARTICIPANTS Adults presenting with acute cough. MAIN OUTCOME MEASURES Pneumonia as determined by radiologists, who were blind to all other information when they judged chest radiographs. RESULTS Of 3106 eligible patients, 286 were excluded because of missing or inadequate chest radiographs, leaving 2820 patients (mean age 50, 40% men) of whom 140 (5%) had pneumonia. Re-assessment of a subset of 1675 chest radiographs showed agreement in 94% (κ 0.45, 95% confidence interval 0.36 to 0.54). Six published "symptoms and signs models" varied in their discrimination (area under receiver operating characteristics curve (ROC) ranged from 0.55 (95% confidence interval 0.50 to 0.61) to 0.71 (0.66 to 0.76)). The optimal combination of clinical prediction items derived from our patients included absence of runny nose and presence of breathlessness, crackles and diminished breath sounds on auscultation, tachycardia, and fever, with an ROC area of 0.70 (0.65 to 0.75). Addition of CRP at the optimal cut off of >30 mg/L increased the ROC area to 0.77 (0.73 to 0.81) and improved the diagnostic classification (net reclassification improvement 28%). In the 1556 patients classified according to symptoms, signs, and CRP >30 mg/L as "low risk" (<2.5%) for pneumonia, the prevalence of pneumonia was 2%. In the 132 patients classified as "high risk" (>20%), the prevalence of pneumonia was 31%. The positive likelihood ratio of low, intermediate, and high risk for pneumonia was 0.4, 1.2, and 8.6 respectively. Measurement of procalcitonin added no relevant additional diagnostic information. A simplified diagnostic score based on symptoms, signs, and CRP >30 mg/L resulted in proportions of pneumonia of 0.7%, 3.8%, and 18.2% in the low, intermediate, and high risk group respectively. CONCLUSIONS A clinical rule based on symptoms and signs to predict pneumonia in patients presenting to primary care with acute cough performed best in patients with mild or severe clinical presentation. Addition of CRP concentration at the optimal cut off of >30 mg/L improved diagnostic information, but measurement of procalcitonin concentration did not add clinically relevant information in this group.
Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative intracellular pathogen that causes disease in a variety of hosts. S. Typhimurium actively invade host cells and typically reside within a membrane-bound compartment called the Salmonella-containing vacuole (SCV). The bacteria modify the fate of the SCV using two independent type III secretion systems (TTSS). TTSS are known to damage eukaryotic cell membranes and S. Typhimurium has been suggested to damage the SCV using its Salmonella pathogenicity island (SPI)-1 encoded TTSS. Here we show that this damage gives rise to an intracellular bacterial population targeted by the autophagy system during in vitro infection. Approximately 20% of intracellular S. Typhimurium colocalized with the autophagy marker GFP-LC3 at 1 h postinfection. Autophagy of S. Typhimurium was dependent upon the SPI-1 TTSS and bacterial protein synthesis. Bacteria targeted by the autophagy system were often associated with ubiquitinated proteins, indicating their exposure to the cytosol. Surprisingly, these bacteria also colocalized with SCV markers. Autophagy-deficient (atg5-/-) cells were more permissive for intracellular growth by S. Typhimurium than normal cells, allowing increased bacterial growth in the cytosol. We propose a model in which the host autophagy system targets bacteria in SCVs damaged by the SPI-1 TTSS. This serves to retain intracellular S. Typhimurium within vacuoles early after infection to protect the cytosol from bacterial colonization. Our findings support a role for autophagy in innate immunity and demonstrate that Salmonella infection is a powerful model to study the autophagy process.
OBJECTIVES To determine the frequency of neurobehavioral signs and symptoms reported in every published case of traumatic encephalopathy with a view toward the development of clinical diagnostic criteria with predictive validity. INTRODUCTION Cases of persistent or progressive neurological or neurobehavioral change following exposure to one or more head injuries have been reported since 1928. This condition is often referred to as traumatic encephalopathy (TE). To date, however, no diagnostic criteria have been advanced or accepted for the clinical diagnosis of TE. Provisional research diagnostic criteria are required not only for meaningful diagnosis but also to facilitate research to determine the epidemiology, etiology, course, prognosis, imaging and biomarkers, neuropathological features and potentially effective treatments of TE. METHODS All 436 published cases of TE in all languages were reviewed. All symptoms and signs reported in these cases were classified and enumerated. RESULTS Ninety-seven cases met inclusion criteria based on sufficient documentation of the history and neurobehavioral examination. Provisional research diagnostic criteria for clinically probable and clinically possible TE were developed based on the most frequently reported clinical features. CONCLUSION The provisional diagnostic criteria for TE presented here are the first published criteria for this condition based upon a systematic analysis of its clinical characteristics. This is the first a step toward scientifically derived consensus criteria, which are essential to accelerate progress in the investigation of this important condition.
In a paper arising out of an informal international consultation of specialists in the bacteriology of tuberculosis held in 1961, an attempt was made to formulate criteria, and specify technical procedures, for reliable tests of sensitivity (the absolute-concentration method, the resistance-ratio method and the proportion method) to the 3 main antituberculosis drugs (isoniazid, streptomycin and p-aminosalicylic acid). Seven years later, a further consultation was held to review the latest developments in the field and to suggest how sensitivity tests might be put to practical use in tuberculosis control programmes. The participants reached agreement on how to define drug sensitivity and resistance, and stressed the importance of using a discrimination approach to the calibration of sensitivity tests. Their views are contained in the present paper, which also includes descriptions of the sensitivity tests used by the Medical Research Council of Great Britain for first- and second-line drugs (minimal inhibitory concentration and resistance-ratio methods), the two main variants of the proportion method developed by the Institut Pasteur, Paris, and a method for calibrating sensitivity tests.
Gram-negative bacteria use the Type VI secretion system (T6SS) to inject toxic proteins into rival bacteria or eukaryotic cells. However, the mechanism of the T6SS is incompletely understood. In the present study, we investigated a conserved component of the T6SS, TssK, using the antibacterial T6SS of Serratia marcescens as a model system. TssK was confirmed to be essential for effector secretion by the T6SS. The native protein, although not an integral membrane protein, appeared to localize to the inner membrane, consistent with its presence within a membrane-anchored assembly. Recombinant TssK purified from S. marcescens was found to exist in several stable oligomeric forms, namely trimer, hexamer and higher-order species. Native-level purification of TssK identified TssF and TssG as interacting proteins. TssF and TssG, conserved T6SS components of unknown function, were required for T6SS activity, but not for correct localization of TssK. A complex containing TssK, TssF and TssG was subsequently purified in vitro, confirming that these three proteins form a new subcomplex within the T6SS. Our findings provide new insight into the T6SS assembly, allowing us to propose a model whereby TssK recruits TssFG into the membrane-associated T6SS complex and different oligomeric states of TssK may contribute to the dynamic mechanism of the system.
Salmonella typhimurium causes a localized enteric infection in immunocompetent individuals, whereas HIV-infected individuals develop a life-threatening bacteremia. Here we show that simian immunodeficiency virus (SIV) infection results in depletion of T helper type 17 (TH17) cells in the ileal mucosa of rhesus macaques, thereby impairing mucosal barrier functions to S. typhimurium dissemination. In SIV-negative macaques, the gene expression profile induced by S. typhimurium in ligated ileal loops was dominated by TH17 responses, including the expression of interleukin-17 (IL-17) and IL-22. TH17 cells were markedly depleted in SIV-infected rhesus macaques, resulting in blunted TH17 responses to S. typhimurium infection and increased bacterial dissemination. IL-17 receptor–deficient mice showed increased systemic dissemination of S. typhimurium from the gut, suggesting that IL-17 deficiency causes defects in mucosal barrier function. We conclude that SIV infection impairs the IL-17 axis, an arm of the mucosal immune response preventing systemic microbial dissemination from the gastrointestinal tract.
Myeloid differentiation factor-2 (MD-2) is a lipopolysaccharide (LPS)-binding protein usually coexpressed with and binding to Toll-like receptor 4 (TLR4), conferring LPS responsiveness of immune cells. MD-2 is also found as a soluble protein. Soluble MD-2 (sMD-2) levels are markedly elevated in plasma from patients with severe infections, and in other fluids from inflamed tissues. We show that sMD-2 is a type II acute-phase protein. Soluble MD-2 mRNA and protein levels are up-regulated in mouse liver after the induction of an acute-phase response. It is secreted by human hepatocytic cells and up-regulated by interleukin-6. Soluble MD-2 binds to Gram-negative but not Gram-positive bacteria, and sMD-2 secreted by hepatocytic cells is an essential cofactor for the activation of TLR4-expressing cells by Gram-negative bacteria. Soluble MD-2 opsonization of Gram-negative bacteria accelerates and enhances phagocytosis, principally by polymorphonuclear neutrophils. In summary, our results demonstrate that sMD-2 is a newly recognized type II acute-phase reactant, an opsonin for Gram-negative bacteria, and a cofactor essential for the activation of TLR4-expressing cells. This suggests that sMD-2 plays a key role in the host innate immune response to Gram-negative infections.
Efficient T cell activation requires both TCR signals and costimulatory signals. CD28 is one of the molecules that provide costimulatory signals for T cells. We used mice deficient in CD28 expression (CD28-/- mice) to analyze the role of CD28 in the immune response against the intracellular bacterium Salmonella typhimurium, the causative agent of murine typhoid fever. CD28-/- mice were highly susceptible to infection with wild-type S. typhimurium and even failed to control infection with attenuated aroA- S. typhimurium. More detailed analysis revealed that CD28-/- animals did not mount a T-dependent Ab response and were highly impaired in the production of IFN-gamma. Thus, CD28 cosignaling is crucial for immunity against S. typhimurium. To our knowledge, this is the first report describing an essential role for CD28 in protective immunity against an intracellular microbial pathogen.
UNLABELLED Cryptococcosis is a multifaceted fungal infection with variable clinical presentation and outcome. As in many infectious diseases, this variability is commonly assigned to host factors. To investigate whether the diversity of Cryptococcus neoformans clinical (ClinCn) isolates influences the interaction with host cells and the clinical outcome, we developed and validated new quantitative assays using flow cytometry and J774 macrophages. The phenotype of ClinCn-macrophage interactions was determined for 54 ClinCn isolates recovered from cerebrospinal fluids (CSF) from 54 unrelated patients, based on phagocytic index (PI) and 2-h and 48-h intracellular proliferation indexes (IPH2 and IPH48, respectively). Their phenotypes were highly variable. Isolates harboring low PI/low IPH2 and high PI/high IPH2 values were associated with nonsterilization of CSF at week 2 and death at month 3, respectively. A subset of 9 ClinCn isolates with different phenotypes exhibited variable virulence in mice and displayed intramacrophagic expression levels of the LAC1, APP1, VAD1, IPC1, PLB1, and COX1 genes that were highly variable among the isolates and correlated with IPH48. Variation in the expression of virulence factors is thus shown here to depend on not only experimental conditions but also fungal background. These results suggest that, in addition to host factors, the patient's outcome can be related to fungal determinants. Deciphering the molecular events involved in C. neoformans fate inside host cells is crucial for our understanding of cryptococcosis pathogenesis. IMPORTANCE Cryptococcus neoformans is a life-threatening human fungal pathogen that is responsible for an estimated 1 million cases of meningitis/year, predominantly in HIV-infected patients. The diversity of infecting isolates is well established, as is the importance of the host factors. Interaction with macrophages is a major step in cryptococcosis pathogenesis. How the diversity of clinical isolates influences macrophages' interactions and impacts cryptococcosis outcome in humans remains to be elucidated. Using new assays, we uncovered how yeast-macrophage interactions were highly variable among clinical isolates and found an association between specific behaviors and cryptococcosis outcome. In addition, gene expression of some virulence factors and intracellular proliferation were correlated. While many studies have established that virulence factors can be differentially expressed as a function of experimental conditions, our study demonstrates that, under the same experimental conditions, clinical isolates behaved differently, a diversity that could participate in the variable outcome of infection in humans.
BACKGROUND Technological advancements in neuroimaging and the increased use of these diagnostic modalities are responsible for the discovery of incidentally identified anomalies within the CNS. In addition to the identification of unanticipated brain MRI abnormalities suggestive of demyelinating disease in patients undergoing neuroimaging for a medical reason other than evaluation for multiple sclerosis (MS), asymptomatic spinal cord lesions are periodically identified. OBJECTIVE To determine if asymptomatic spinal cord lesions are associated with clinical progression in subjects with radiologically isolated syndrome (RIS). METHODS A retrospective review of RIS cases at the University of California, San Francisco Multiple Sclerosis Center was performed. The presence of asymptomatic cervical spinal cord MRI lesions was analyzed as a potential predictor for clinical progression. RESULTS Twenty-five of 71 subjects with RIS possessed findings within the cervical spine that were highly suggestive of demyelinating disease. Of these subjects, 21 (84%) progressed clinically to clinically isolated syndrome (n = 19) or primary progressive multiple sclerosis (n = 2) over a median time of 1.6 years from the date of RIS identification (interquartile range 0.8-3.8). The sensitivity, specificity, and positive predictive value of an asymptomatic spinal cord lesion for subsequent development of either a first demyelinating attack or primary progressive MS were 87.5%, 91.5%, and 84%, respectively. The odds ratio of clinical progression was 75.3 (95% confidence interval 16.1-350.0, p < 0.0001). This association remained significant after adjusting for potential confounders. CONCLUSION These findings suggest that the presence of asymptomatic spinal cord lesions place subjects with RIS at substantial risk for clinical conversion to either an acute or progressive event, a risk that is independent of brain lesions on MRI.