Dynamics of PCR-based diagnosis in patients with invasive meningococcal disease

Clinical application and evaluation of metagenomic next-generation sequencing in pathogen detection for suspected central nervous system infections

Central nervous system Infections (CNSIs) is a disease characterized by complex pathogens, rapid disease progression, high mortality rate and high disability rate. Here, we evaluated the clinical value of metagenomic next generation sequencing (mNGS) in the diagnosis of central nervous system infections and explored the factors affecting the results of mNGS. We conducted a retrospective study to compare mNGS with conventional methods including culture, smear and etc. 111 suspected CNS infectious patients were enrolled in this study, and clinical data were recorded. Chi-square test were used to evaluate independent binomial variables, taking p < 0.05 as statistically significant threshold. Of the 111 enrolled cases, 57.7% (64/111) were diagnosed with central nervous system infections. From these cases, mNGS identified 39.6% (44/111) true-positive cases, 7.2% (8/111) false-positive case, 35.1% (39/111) true-negative cases, and 18.0% (20/111) false-negative cases. The sensitivity and specificity of mNGS were 68.7% (44/64) and 82.9% (39/47), respectively. Compared with culture, mNGS provided a higher pathogen detection rate in CNSIs patients (68.7% (44/64) vs. 26.5% (17/64), p < 0.0001). Compared to conventional methods, positive percent agreement and negative percent agreement was 84.60% (44/52) and 66.1% (39/59) separately. At a species-specific read number (SSRN) ≥ 2, mNGS performance in the diagnosis of definite viral encephalitis and/or meningitis was optimal (area under the curve [AUC] 0.758, 95% confidence interval [CI] 0.663-0.854). In bacterial CNSIs patients with significant CSF abnormalities (CSF WBC > 300*106/L), the positive rate of CSF mNGS is higher. To sum up, conventional microbiologic testing is insufficient to detect all neuroinvasive pathogens, and mNGS exhibited satisfactory diagnostic performance in CNSIs and with an overall detection rate higher than culture (p < 0.0001).

Distinguishing community-acquired bacterial and viral meningitis: Microbes and biomarkers

Diagnostic tools to differentiate between community-acquired bacterial and viral meningitis are essential to target the potentially lifesaving antibiotic treatment to those at greatest risk and concurrently spare patients with viral meningitis from the disadvantages of antibiotics. In addition, excluding bacterial meningitis and thus decreasing antibiotic consumption would be important to help reduce antimicrobial resistance and healthcare expenses. The available diagnostic laboratory tests for differentiating bacterial and viral meningitis can be divided microbiological pathogen-focussed methods and biomarkers of the host response. Bacterial culture-independent microbiological methods, such as highly multiplexed nucleic acid amplification tests, are rapidly making their way into the clinical practice. At the same time, more conventional host protein biomarkers, such as procalcitonin and C-reactive protein, are supplemented by newer proteomic and transcriptomic signatures. This review aims to summarise the current state and the recent advances in diagnostic methods to differentiate bacterial from viral meningitis.

Multiplex real-time PCR FilmArray performance in the diagnosis of meningoencephalitis: lights and shadows

PURPOSE

We aimed to evaluate the performance of the FilmArray (FA) meningitis/encephalitis (ME) panel. Secondarily, we analyzed the false positive (FP) and false negative (FN) results, as well as the predictive values of the technique, regarding the cerebrospinal fluid (CSF) characteristics.

METHODS

FA is a multiplex real-time PCR detecting 14 of the most common ME pathogens in CSF. All FA performed at our hospital (2018-2022) were retrospectively reviewed. FA was compared to conventional techniques and its performance was assessed based on the final diagnosis of the episode.

RESULTS

FA was performed in 313 patients with suspicion of ME. Most patients had altered mental status (65.2%) and fever (61%). Regarding CSF characteristics, 49.8% and 53.7% presented high CSF proteins and pleocytosis, respectively. There were 84 (26.8%) positive FA results, mainly for HSV-1 (10.9%), VZV (5.1%), Enterovirus (2.6%), and S. pneumoniae (1.9%). In the 136 cases where both FA and routine methods were performed, there was a 25.7% lack of agreement. We identified 6.6% FN results, but 28.6% FP, mainly due to HSV-1. This resulted in a high negative predictive value (NPV) of 93.4%, but a positive predictive value (PPV) of 73%. Remarkably, PPV as low as 36.9%, and 70.2%, were found in cases without pleocytosis, or lack of high CSF protein levels, respectively.

CONCLUSION

FA was associated with high NPV, but frequent FP results and low PPV, particularly for HSV-1, and especially in patients without high CSF protein levels or pleocytosis.

High risk and low prevalence diseases: Adult bacterial meningitis

INTRODUCTION

Acute bacterial meningitis in adults is a rare but serious condition that carries a high rate of morbidity.

OBJECTIVE

This review highlights pearls and pitfalls of acute bacterial meningitis in adults, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Meningitis encompasses a broad spectrum of disease involving inflammation of the meninges and subarachnoid space. It classically presents with fever, nuchal rigidity, and altered mental status, but this triad is not present in all cases. Up to 95% of patients will have at least two of the following four cardinal symptoms: fever, nuchal rigidity, altered mental status, and headache. The most common bacterial etiologies are S. pneumoniae and N. meningitidis. Cerebrospinal fluid testing obtained by lumbar puncture remains the gold standard in diagnosis. Head computed tomography prior to lumbar puncture may not be necessary in most patients. Empiric treatment consists of vancomycin, ceftriaxone, and dexamethasone. Elevated intracranial pressure should be managed using established neurocritical care strategies.

CONCLUSION

A better understanding of the pearls and pitfalls of acute bacterial meningitis can assist emergency clinicians in pursuing its timely diagnosis and management.

Molecular characterization of invasive Neisseria meningitidis isolates collected in Lithuania (2009-2019) and estimation of serogroup B meningococcal vaccine 4CMenB and MenB-Fhbp coverage

Neisseria meningitidis causes invasive meningococcal disease (IMD), which is associated with significant mortality and long-term consequences, especially among young children. The incidence of IMD in Lithuania was among the highest in European Union/European Economic Area countries during the past two decades; however, the characterization of meningococcal isolates by molecular typing methods has not yet been performed. In this study, we characterized invasive meningococcal isolates (n=294) recovered in Lithuania from 2009 to 2019 by multilocus sequence typing (MLST) and typing of antigens FetA and PorA. The more recent (2017-2019) serogroup B isolates (n=60) were genotyped by analyzing vaccine-related antigens to evaluate their coverage by four-component (4CMenB) and two-component (MenB-Fhbp) vaccines using the genetic Meningococcal Antigen Typing System (gMATS) and Meningococcal Deduced Vaccine Antigen Reactivity (MenDeVAR) Index methods, respectively. The vast majority (90.5%) of isolates belonged to serogroup B. MLST revealed a predominance of clonal complex 32 (74.02%). Serogroup B strain P1.19,15: F4-28: ST-34 (cc32) accounted for 64.1% of IMD isolates. The overall level of strain coverage by the 4MenB vaccine was 94.8% (CI 85.9-98.2%). Most serogroup B isolates (87.9%) were covered by a single vaccine antigen, most commonly Fhbp peptide variant 1 (84.5% of isolates). The Fhbp peptides included in the MenB-Fhbp vaccine were not detected among the analyzed invasive isolates; however, the identified predominant variant 1 was considered cross-reactive. In total, 88.1% (CI 77.5-94.1) of isolates were predicted to be covered by the MenB-Fhbp vaccine. In conclusion, both serogroup B vaccines demonstrate potential to protect against IMD in Lithuania.

Analysis of the Clinical Impact of the BioFire FilmArray Meningitis Encephalitis Panel on Antimicrobial Use and Duration of Therapy at an Academic Medical Center

The purpose of this study was to assess the clinical impact of the BioFire FilmArray Meningitis/Encephalitis (ME) panel on antimicrobial use and clinical outcomes. This retrospective, quasi-experiment evaluated adult and pediatric patients with suspected ME, evidenced by cerebrospinal fluid (CSF) culture. Hospital-acquired meningitis patients and patients who received antimicrobials >48 h prior to lumbar puncture were excluded. The primary endpoint was days of antimicrobial therapy pre- and post-implementation of the ME panel. Secondary endpoints included total length of stay, 30-day readmission, and individual days of antimicrobial therapy. Two hundred and sixty-four total adult and pediatric patients were included. Antimicrobial days of therapy had a median of 3 days (IQR 0−5) in the pre vs. post group with a median of 2 days (2−5) (p = 0.099). Days of therapy for acyclovir were significantly decreased in the post group (median 2 days [IQR 1−3] vs. 3 days [IQR 2.5−4.5], p = 0.0002). There were no significant differences in the secondary endpoints. Overall, implementation of the ME panel impacted the duration of antimicrobials, particularly acyclovir; however, opportunities for further education regarding antimicrobial de-escalation and utilization of the panel were identified. Antimicrobial stewardship program intervention is critical to maximize benefit of this rapid diagnostic test.

Application of metagenomic next-generation sequencing in the diagnosis of infectious diseases of the central nervous system after empirical treatment

BACKGROUND

The diagnostic value of metagenomic next-generation sequencing (mNGS) in central nervous system (CNS) infectious diseases after empirical treatment has not been reported.

AIM

To investigate the diagnostic value of mNGS of cerebrospinal fluid (CSF) in the empirically treated CNS infectious diseases.

METHODS

A total of 262 CSF samples from patients with suspected CNS infections were collected between August 2020 and December 2021. Both mNGS and conventional methods were used for testing. The conventional methods included microbial culture, smear, polymerase chain reaction, etc.

RESULTS

Among 262 suspected cases, 183 cases (69.84%) were diagnosed as CNS infection, including 86 cases of virus infection (47.00%), 70 cases of bacterial infection (38.25%) and 27 cases of fungal infection (14.76%). The sensitivity and specificity of mNGS were 65.6% (95%CI: 58.2%-72.3%) and 89.6% (95%CI: 79.1%-95.3%), respectively. The PPV of mNGS was 94.5% (95%CI: 88.6%-97.6%), and the NPV was 48.8% (95%CI: 39.7%–57.9%). The pathogen detective sensitivity and accuracy of mNGS were higher than those of conventional methods (Sensitivity: 65.6% vs 37.2%; P < 0.001; Accuracy: 72.0% vs 50%, P < 0.001). The results showed that compared with conventional methods, mNGS technology was a more sensitive method for the diagnosis of CNS infection after empirical treatment.

CONCLUSION

mNGS can be a better method applied in the diagnosis of CNS infection after empirical treatment.

Invasive meningococcal disease in older adults in North America and Europe: is this the time for action? A review of the literature

BACKGROUND

Neisseria meningitidis is an encapsulated Gram-negative diplococcus that asymptomatically colonises the upper respiratory tract in up to 25% of the population (mainly adolescents and young adults). Invasive meningococcal disease (IMD) caused by Neisseria meningitidis imposes a substantial public health burden,. The case fatality rate (CFR) of IMD remains high. IMD epidemiology varies markedly by region and over time, and there appears to be a shift in the epidemiology towards older adults. The objective of our review was to assess the published data on the epidemiology of IMD in older adults (those aged ≥ 55 years)in North America and Europe. Such information would assist decision-makers at national and international levels in developing future public health programmes for managing IMD.

METHODS

A comprehensive literature review was undertaken on 11 August 2020 across three databases: EMBASE, Medline and BIOSIS. Papers were included if they met the following criteria: full paper written in the English language; included patients aged ≥ 56 years; were published between 1/1/2009 11/9/2020 and included patients with either suspected or confirmed IMD or infection with N. meningitidis in North America or Europe. Case studies/reports/series were eligible for inclusion if they included persons in the age range of interest. Animal studies and letters to editors were excluded. In addition, the websites of international and national organisations and societies were also checked for relevant information.

RESULTS

There were 5,364 citations identified in total, of which 76 publications were included in this review. We identified that older adults with IMD were mainly affected by serogroups W and Y, which are generally not the predominant strains in circulation in most countries. Older adults had the highest CFRs, probably linked to underlying comorbidities and more atypical presentations hindering appropriate timely management. In addition, there was some evidence of a shift in the incidence of IMD from younger to older adults.

CONCLUSIONS

The use of meningococcal vaccines that include coverage against serogroups W and Y in immunization programs for older adults needs to be evaluated to inform health authorities' decisions of the relative benefits of vaccination and the utility of expanding national immunization programmes to this age group.

Laboratory diagnosis of bacterial meningitis by direct detection, serotyping and Next Generation Sequencing: How 10 years of testing in New York State has evolved to improve laboratory diagnosis and public health

Since 2005, the Wadsworth Center (WC) has provided molecular testing on cerebrospinal fluid (CSF) and whole blood specimens in close collaboration with epidemiologists in New York State and New York City. In this study, we analyzed 10 years of data to demonstrate the significant value of utilizing molecular methods to assess patient specimens for etiologic agents of bacterial meningitis. A comprehensive molecular testing algorithm to detect and serotype/serogroup bacterial agents known to cause bacterial meningitis (Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus agalactiae) has evolved, and retrospective specimen testing has been essential for each improvement. Over a ten-year span from 2010 to 2019 the WC received 831 specimens from 634 patients with suspected bacterial meningitis. Real-time PCR was positive for at least one of the agents in 223 (27%) specimens from 183 patients (29%). Of the 223 positives, 146 (66%) were further characterized by real-time PCR into serogroup/serotype. Additionally, examination of 131 paired specimens of CSF and whole blood from the same patients found better detection in CSF, but whole blood is a useful alternative for diagnosis when CSF is not available. For specimens initially PCR-negative, 16S rDNA Sanger sequencing was requested by the submitter for 146 cases resulting in the identification of bacterial agents in an additional 24 (16%) specimens. In a retrospective study, Next Generation Sequencing (NGS) was evaluated for the detection of pathogens in 53 previously tested PCR-negative CSF specimens and identified bacteria in 14 (26%) specimens. This molecular testing algorithm has provided clinicians a diagnosis when culture is negative with the potential to guide therapy. It has also aided public health in determining when antibiotic prophylaxis was needed, augmented surveillance data to yield a fuller picture of community prevalence, and highlighted gaps in the spectrum of agents that cause bacterial meningitis.

Longitudinal study of meningococcal carriage rates in university entrants living in a dormitory in South Korea

University students, especially those living in dormitories, are known to have a high risk of invasive meningococcal disease. We performed a longitudinal study to investigate the change in Neisseria meningitidis carriage rates and identify the risk factors for carriage acquisition in university students in South Korea. We recruited university entrants who were admitted to a student dormitory. Pharyngeal swabs were taken from participants at baseline, 1 month, and 3 months, and the subjects completed a questionnaire. Culture and real-time polymerase chain reaction (PCR) for species-specific ctrA and sodC genes were performed. The cultured isolates or PCR-positive samples were further evaluated for epidemiologic characterization using serogrouping, PorA typing, FetA typing, and multilocus sequence typing (MLST). At the first visit, we enrolled 332 participants who were predominantly male (64.2%) with a median age of 19 years. Meningococcal carriage rates increased from 2.7% (95% confidence interval [CI] 0.9–4.4%) at baseline to 6.3% (95% CI 3.4–9.0%) at 1 month and 11.8% (95% CI 7.8–15.6%) at 3 months. Nongroupable isolates accounted for 50.0% of all isolates, with serogroup B being the next most prevalent (24.1%). In the study population, male sex (OR 2.613, 95% CI 1.145–5.961, p = 0.022) and frequent pub or club visits (OR 3.701, 95% CI 1.536–8.919, p = 0.004) were significantly associated with meningococcal carriage. Based on serotype and MLST analyses, six carriers transmitted meningococci to other study participants. N. meningitidis carriage rates among new university entrants who lived in a dormitory significantly increased within the first 3 months of dormitory stay, probably owing to the transmission of identical genotype among students. Based on the risk of meningococcal disease, meningococcal vaccination should be considered for students before dormitory admission.

Retrospective analysis of the etiology, clinical characteristics and outcomes of community-acquired bacterial meningitis in the University Infectious Diseases Centre in Lithuania

Background

The morbidity and mortality in community-acquired bacterial meningitis (CABM) remain substantial, and the etiology, clinical characteristics, treatment outcomes and predictors of poor prognosis must be assessed regularly. The aim of this study was to identify the distribution of etiological agents and their relationship with clinical characteristics, treatment and outcomes in this cohort of patients with CABM.

Methods

Our retrospective chart review analyzed the causative microorganisms, clinical characteristics, laboratory findings, treatment and outcomes of 159 adults with CABM hospitalized in the Infectious Diseases Centre of Vilnius University Hospital from January 1, 2009 to December 31, 2016. A Glasgow Outcome Scale (GOS) score ≤ 3 was defined as unfavorable outcome. Predictors of an unfavorable outcome were identified through logistic regression analysis.

Results

The median patient age was 36 (IQR 24–56), and 51.6% were male. Microbiologically confirmed causative agents were identified in 80 (50.3%) patients: N. meningitidis in 55 (34.6%) patients with serotype B accounting for 85% of cases, S. pneumoniae in 15 (9.4%), L. monocytogenes in 5 (3.1%) and other in 5 (3.1%). The clinical triad of fever, neck stiffness and a change in mental status was present in 59.1% of patients. Coexisting conditions and comorbidities were similar in all groups stratified by etiology. Initial antimicrobial treatment consisted of penicillin in 78 patients (49.1%) and ceftriaxone in 72 patients (45.3%). The median time in which antibiotic treatment was started was 40 min (IQR 30.0–90.0). The outcome was unfavorable in 15.7% of episodes and death occurred in 5.7% of cases and did not differ according to the causative agent. Risk factors for an unfavorable outcome were age > 65 years, coexisting pneumonia and a platelet count <150x10e9/l.

Conclusions

The most common causative agent of CABM was N. meningitidis, with serotype B clearly dominant. Causative agents did not influence the disease outcome. The strongest risk factors for an unfavorable outcome were older age, pneumonia and a low platelet count. Since the introduction of routine vaccination against meningococcus B for infants in Lithuania in 2018, the national vaccination policy may hopefully contribute to a decrease in the incidence of serogroup B meningococcal disease in the Lithuanian population.

Clinical application and evaluation of metagenomic next-generation sequencing in suspected adult central nervous system infection

BACKGROUND

Accurate etiology diagnosis is crucial for central nervous system infections (CNS infections). The diagnostic value of metagenomic next-generation sequencing (mNGS), an emerging powerful platform, remains to be studied in CNS infections.

METHODS

We conducted a single-center prospective cohort study to compare mNGS with conventional methods including culture, smear and etc. 248 suspected CNS infectious patients were enrolled and clinical data were recorded.

RESULTS

mNGS reported a 90.00% (9/10) sensitivity in culture-positive patients without empirical treatment and 66.67% (6/9) in empirically-treated patients. Detected an extra of 48 bacteria and fungi in culture-negative patients, mNGS provided a higher detection rate compared to culture in patients with (34.45% vs. 7.56%, McNemar test, p < 0.0083) or without empirical therapy (50.00% vs. 25.00%, McNemar test, p > 0.0083). Compared to conventional methods, positive percent agreement and negative percent agreement was 75.00% and 69.11% separately. mNGS detection rate was significantly higher in patients with cerebrospinal fluid (CSF) WBC > 300 * 10⁶/L, CSF protein > 500 mg/L or glucose ratio ≤ 0.3. mNGS sequencing read is correlated with CSF WBC, glucose ratio levels and clinical disease progression.

CONCLUSION

mNGS showed a satisfying diagnostic performance in CNS infections and had an overall superior detection rate to culture. mNGS may held diagnostic advantages especially in empirically treated patients. CSF laboratory results were statistically relevant to mNGS detection rate, and mNGS could dynamically monitor disease progression.

Validation of multiplex PCR for the diagnosis of acute bacterial meningitis in culture negative cerebrospinal fluid

INTRODUCTION

This study evaluated the operational characteristics of the multiplex polymerase chain reaction (PCR) for cerebrospinal fluid (CSF) from patients with cellular and biochemical characteristics of acute bacterial meningitis and positive or negative CSF cultures.

METHODS

Multiplex PCR was performed for 36 CSF samples: culture-proven acute bacterial meningitis (n = 7), culture-negative acute bacterial meningitis (n = 17), lymphocytic meningitis (n = 8), and normal CSF (n = 4). The operational characteristics of multiplex PCR were evaluated with definite and probable bacterial meningitis, using culture positive, cytological and biochemical CSF characteristics as the gold standard.

RESULTS

Multiplex PCR for CSF was efficient in the group with CSF cellular and biochemical characteristics of acute bacterial meningitis but with a negative CSF culture. This group demonstrated high specificity, positive predictive value, and efficiency.

CONCLUSIONS

Multiplex PCR for CSF can improve the speed and accuracy of acute bacterial meningitis diagnosis in a clinical setting as a complement to classical immunological and bacteriological assays in CSF. It is also useful for CSF culture-negative acute bacterial meningitis.

Etiology of Central Nervous System Infections in a Rural Area of Nepal Using Molecular Approaches

The etiology of infections of the central nervous system (CNS) in Nepal often remains unrecognized because of underdeveloped laboratory facilities. The aim of this study was to investigate the etiology of CNS infections in a rural area of Nepal using molecular methods. From November 2014 to February 2016, cerebrospinal fluid (CSF) was collected from 176 consecutive patients presenting at United Mission Hospital in Tansen, Nepal, with symptoms of possible CNS infection. After the CSF samples were stored and transported frozen, polymerase chain reaction (PCR) was performed in Sweden, targeting a total of 26 pathogens using the FilmArray^® ME panel (BioFire, bioMerieux, Salt Lake City, UT), the MeningoFinder^® 2SMART (PathoFinder, Maastricht, The Netherlands), and an in-house PCR test for dengue virus (DENV), Japanese encephalitis virus (JEV), and Nipah virus (NiV). The etiology could be determined in 23%. The bacteria detected were Haemophilus influenzae (n = 5), Streptococcus pneumoniae (n = 4), and Neisseria meningitidis (n = 1). The most common virus was enterovirus detected in eight samples, all during the monsoon season. Other viruses detected were cytomegalovirus (n = 6), varicella zoster virus (n = 5), Epstein–Barr virus (n = 3), herpes simplex virus (HSV) type 1 (HSV-1) (n = 3), HSV-2 (n = 3), human herpes virus (HHV) type 6 (HHV-6) (n = 3), and HHV-7 (n = 2). Cryptococcus neoformans/gatti was found in four samples. None of the samples were positive for DENV, JEV, or NiV. Of the patients, 67% had been exposed to antibiotics before lumbar puncture. In conclusion, the etiology could not be found in 77% of the samples, indicating that the commercial PCR panels used are not suitable in this setting. Future studies on the etiology of CNS infections in Nepal could include metagenomic techniques.

Frequency and Associated Factors of Parental Refusal to Perform Lumbar Puncture in Children with Suspected Central Nervous System Infection: A Cross-sectional Study

Objective

Lumbar puncture (LP) is a useful procedure which is performed for both diagnosis and treatment of numerous conditions affecting children and adults. The purpose of this study was to determine the frequency and cause of increased parental refusal to perform LP in the pediatric population.

Method

A cross-sectional study was conducted from January 2018 to June 2019 at the Civil Hospital, Dow University of Health Sciences, pediatric department, Civil Hospital, Karachi. Over the 18-month time period, a total of 215 patients who had indications of LP were selected from the in-patient pediatrics department; the age range was between newborn to 12 years of age. The mode of research was a questionnaire and interview-based method that was conducted with guardians of minor patients to understand the extent of their knowledge and awareness about the LP procedure as well as its complication and the role of culture, education background, and financial status of the families which may lead to an increased likelihood of refusal.

Result

The frequency of LP refusal amongst the 215 families of the patients that were interviewed was found to be 32.6%. Mean age of the respondents was 30.98 years. The decision for LP was not significantly affected by the subjects’ gender (p=0.1), by the religious communities to which the families belonged (p=0.9), their ethnicities (0.52), or by the families’ financial status (p=0.4). It was observed that when indications for performing LP were appropriately explained, there was a significantly greater number of consents given as compared to when they were not made clear (p=0.009). Explaining the complications of the procedure did not considerably impact the decision for refusal of the procedure (p=0.1). The multi-variable logistic regression analysis model was applied to determine the likelihood of variables affecting refusal of LP and the logistic regression model was found to be statistically significant, χ2 (8) = 38.2 p < 0. 001.

Conclusion

Lack of knowledge about the LP procedure and fear of ramification plays a conspicuous role in the denial of LP procedure by the guardians of minor patients. A better, simpler approach using standardized consent forms by the doctors may lead to the removal of the information gaps and can provide a better understanding about the concerned risks, the primary indications, and the benefits of this procedure to the guardians.

Emergence of Neisseria meningitidis Serogroup W, Central African Republic, 2015-2016

We analyzed data from the 2015 and 2016 meningitis epidemic seasons in Central African Republic as part of the national disease surveillance. Of 80 tested specimens, 66 belonged to meningococcal serogroup W. Further analysis found that 97.7% of 44 isolates belonged to the hyperinvasive clonal complex sequence type 11.

Prevalence and serogroup changes of Neisseria meningitidis in South Korea, 2010-2016

Determination of the major serogroups is an important step for establishing a vaccine programme and management strategy targeting Neisseria meningitidis. From April 2010 to November 2016, a total of 25 N. meningitidis isolates were collected in South Korea, in collaboration with the Korean Society of Clinical Microbiology. Among isolates, 19 isolates were recovered from blood and/or cerebrospinal fluid (CSF) in 46 patients who suffered from invasive meningococcal disease (IMD), and six isolates were found in sputum or the throat. The most common serogroup was serogroup B (overall, 36%, n = 9/25; IMD, 37%, n = 7/19), which was isolated in every year of the research period except for 2011. There were five serogroup W isolates recovered from patients in military service. W was no longer isolated after initiation of a vaccine programme for military trainees, but serogroup B caused meningitis in an army recruit training centre in 2015. In MLST analysis, 14 sequence types were found, and all isolates belonging to W showed the same molecular epidemiologic characteristics (W:P1.5-1, 2-2:F3-9:ST-8912). All isolates showed susceptibility to ceftriaxone, meropenem, ciprofloxacin, minocycline, and rifampin; however, the susceptibility rates to penicillin and ampicillin for isolates with W and C capsules were 22% and 30%, respectively.

Rapid and Accurate Diagnosis of Acute Pyogenic Meningitis Due to Streptococcus Pneumoniae, Haemophilus influenzae Type b and Neisseria meningitidis Using A Multiplex PCR Assay

INTRODUCTION

Acute bacterial meningitis is one of the major causes of morbidity and mortality in children and geriatric population, especially in developing countries. Methods of identification are standard culture and other phenotypic tests in many resource poor settings.

AIM

To use molecular methods for the improvement of aetiological diagnosis of acute pyogenic meningitis in patients.

MATERIALS AND METHODS

CSF samples of 125 patients were included for the study. Gram staining and culture were performed according to standard procedures. Antigen was detected using commercial latex agglutination test kit. Multiplex PCR was performed using previously published primers and protocols. Fischer's exact test was used for finding association between presence of the disease and clinical/biochemical parameters, considering two tailed p<0.05 as statistically significant. Sensitivity, specificity, positive and negative predictive values were calculated using Graphpad QuicCalc software.

RESULTS

A total of 39 cases (31.2%) were confirmed to be of acute pyogenic meningitis based on biochemical methods. Only 10/39 was positive for the three organisms tested. Multiplex PCR was able to detect one additional isolate each of Streptococcus pneumoniae and Haemophilus influenzae type b. When compared with multiplex PCR as the gold standard, culture and latex agglutination tests had same sensitivity (80%), specificity (100%), PPV (100%) and NPV (97.8%), whereas Gram stain had poor sensitivity (40%) and good specificity (95.6%). Detection rates were higher in multiplex PCR for the two organisms Streptococcus pneumoniae and Haemophilus influenzae type b.

CONCLUSION

Multiplex PCR was more sensitive than culture or antigen detection, and employing this assay can significantly increase the speed and accuracy of identification of the pathogen.

Acute bacterial meningitis in adults

Over the past several decades, the incidence of bacterial meningitis in children has decreased but there remains a significant burden of disease in adults, with a mortality of up to 30%. Although the pathogenesis of bacterial meningitis is not completely understood, knowledge of bacterial invasion and entry into the CNS is improving. Clinical features alone cannot determine whether meningitis is present and analysis of cerebrospinal fluid is essential for diagnosis. Newer technologies, such as multiplex PCR, and novel diagnostic platforms that incorporate proteomics and genetic sequencing, might help provide a quicker and more accurate diagnosis. Even with appropriate antimicrobial therapy, mortality is high and so attention has focused on adjunctive therapies; adjunctive corticosteroids are beneficial in certain circumstances. Any further improvements in outcome are likely to come from either modulation of the host response or novel approaches to therapy, rather than new antibiotics. Ultimately, the best hope to reduce the disease burden is with broadly protective vaccines.

Clinical diagnoses and outcomes of 4619 hospitalised cases of laboratory-confirmed invasive meningococcal disease in England: Linkage analysis of multiple national databases

BACKGROUND

Invasive meningococcal disease (IMD) is rare but remains one of the most feared infectious diseases worldwide. We linked multiple national datasets to describe disease characteristics and outcomes of IMD in England over a five-year period.

METHODS

IMD cases confirmed by Public Health England (2007-11) were linked with national hospitalisation records and death registrations. Cases were analysed by age, gender, capsular group, clinical presentation, diagnostic test and outcome. Risk factors for death were assessed using multivariable logistic regression.

RESULTS

Overall, 4619 of 5115 (90.30%) laboratory-confirmed IMD cases were successfully linked to a hospitalisation record. Group B meningococci were responsible for 87.33% (n = 4034) of hospitalised IMD cases, ranging from 93.56% (2294/2452) in <15 year-old to 53.52% (152/284) among ≥65 year-old. Most cases presented with meningitis only (n = 2057, 44.53%), septicaemia only (n = 1725, 37.35%) or both meningitis and septicaemia (n = 389, 8.42%). Over half the cases (2526/4619, 54.69%) were confirmed by PCR only, 22.91% (1058/4619) by culture only and 22.41% (1035/4619) by both. The case fatality rate was 4.46% (206/4619; 95% CI, 3.88-5.10%) and varied by age, clinical presentation and capsular group. Children under 15 years who died within 30 days of diagnosis were significantly more likely to have been diagnosed by culture than by PCR alone (OR, 1.56; 95% CI, 1.02-2.39; P = 0.040).

CONCLUSIONS

We identified complex interactions between age, meningococcal capsular group, clinical presentation, diagnostic method and death. The recent introduction of two new meningococcal immunisation programmes in the UK should significantly reduce IMD cases and deaths in the coming years.

Severe Acute Cholangitis with Complications of Bacterial Meningitis Associated with Hearing Loss

We herein report a case of severe acute cholangitis complicated by bacterial meningitis. A 56-year-old Japanese man was admitted to our hospital due to a consciousness disorder that had developed while he was being treated for acute cholangitis. The levels of both hepatobiliary enzymes and inflammatory markers were high, and computed tomography revealed common bile duct stones and cholangiectasis. A diagnosis of acute cholangitis was made, and meningitis was subsequently confirmed on a cerebrospinal fluid analysis. The patient recovered successfully after receiving emergency endoscopic drainage and antibiotic therapy. This case demonstrates that a disturbance of consciousness complicated by acute cholangitis may result from septic encephalopathy as well as meningitis via bloodstream infections.

The Impact of Appropriate Antibiotic Prescribing on Treatment Evaluation Parameters

The therapeutic impact of inappropriate prescribing of antibiotics is debatable, particularly in situations where infections are treated empirically with multiply prescribed antibiotics. Prescribers may remain under the illusion that such prescriptions are appropriate on the basis of any observed positive treatment outcomes, even though an antibiotic prescribed in such combination therapy may actually be infective against infecting pathogens. This, inevitably, promotes inappropriate antibiotic prescribing. Prescribers may be motivated to make more conscious attempts to prescribe antibiotics appropriately if it is proven that judicious prescribing of antibiotics has positive impacts on treatment outcomes. The objective of this study was to determine the impact of appropriate prescribing of antibiotics on treatment outcomes, days of patient hospitalization and costs related to antibiotic treatment. Observational data on antibiotic treatment were collected for a one-month period from case notes of all inpatients (n=307) and outpatients (n=865) at five government and mission hospitals in Lesotho. Prescriptions were classified into categories of appropriateness based on extents to which antibiotics were prescribed according to principles. Treatment success rates, mean days of hospitalization and costs of antibiotic treatments of inpatients treated with specified prescription categories were determined. Appropriate prescribing of antibiotics for inpatients had positive impacts on treatment outcomes, patients' days of hospitalization for infections and costs of antibiotic treatments. In outpatient settings, appropriate prescribing of antibiotics failed to show any significant impact on costs of antibiotics. Appropriate prescribing of antibiotics had a positive impact on patients' recovery and costs of antibiotic treatments in inpatient settings.

Added value of PCR-testing for confirmation of invasive meningococcal disease in England

OBJECTIVES

In England, national guidance recommends that all patients with suspected invasive meningococcal disease (IMD) should be investigated by blood culture and polymerase chain reaction (PCR) testing. The Meningococcal Reference Unit (MRU) provides a national service for meningococcal species confirmation and PCR-testing of clinical samples. We performed a population-level assessment of the added value of PCR-testing for IMD to augment traditional culture confirmation.

METHODS

We analysed all PCR-samples and invasive meningococcal isolates received by MRU in 2009 and 2010. We assumed that all patients with PCR-samples submitted to MRU also had blood cultures performed and that positive blood cultures were referred to MRU. We confirmed this assertion by case ascertainment.

RESULTS

In total, 25,379 specimens from 22,039 patients were submitted for PCR-testing and 1492 (6.8%) tested PCR-positive. MRU received 825 invasive meningococcal isolates; 393 confirmed by PCR and culture, 405 without a PCR-specimen submitted and 27 with a PCR-negative result. Thus, of 1924 reported IMD cases, 1099 (57.1%) were confirmed by PCR only, 432 (22.5%) by culture only and 393 (20.4%) by both tests.

CONCLUSION

More than half of all confirmed IMD cases were confirmed by PCR only, indicating this service ensures high case ascertainment for national surveillance.

Accuracy of real-time PCR, Gram stain and culture for Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae meningitis diagnosis

BACKGROUND

Although cerebrospinal fluid (CSF) culture is the diagnostic reference standard for bacterial meningitis, its sensitivity is limited, particularly when antibiotics were previously administered. CSF Gram staining and real-time PCR are theoretically less affected by antibiotics; however, it is difficult to evaluate these tests with an imperfect reference standard.

METHODS AND FINDINGS

CSF from patients with suspected meningitis from Salvador, Brazil were tested with culture, Gram stain, and real-time PCR using S. pneumoniae, N. meningitidis, and H. influenzae specific primers and probes. An antibiotic detection disk bioassay was used to test for the presence of antibiotic activity in CSF. The diagnostic accuracy of tests were evaluated using multiple methods, including direct evaluation of Gram stain and real-time PCR against CSF culture, evaluation of real-time PCR against a composite reference standard, and latent class analysis modeling to evaluate all three tests simultaneously.

RESULTS

Among 451 CSF specimens, 80 (17.7%) had culture isolation of one of the three pathogens (40 S. pneumoniae, 36 N. meningitidis, and 4 H. influenzae), and 113 (25.1%) were real-time PCR positive (51 S. pneumoniae, 57 N. meningitidis, and 5 H. influenzae). Compared to culture, real-time PCR sensitivity and specificity were 95.0% and 90.0%, respectively. In a latent class analysis model, the sensitivity and specificity estimates were: culture, 81.3% and 99.7%; Gram stain, 98.2% and 98.7%; and real-time PCR, 95.7% and 94.3%, respectively. Gram stain and real-time PCR sensitivity did not change significantly when there was antibiotic activity in the CSF.

CONCLUSION

Real-time PCR and Gram stain were highly accurate in diagnosing meningitis caused by S. pneumoniae, N. meningitidis, and H. influenzae, though there were few cases of H. influenzae. Furthermore, real-time PCR and Gram staining were less affected by antibiotic presence and might be useful when antibiotics were previously administered. Gram staining, which is inexpensive and commonly available, should be encouraged in all clinical settings.

Dilemmas in the diagnosis of acute community-acquired bacterial meningitis

Rapid diagnosis and treatment of acute community-acquired bacterial meningitis reduces mortality and neurological sequelae, but can be delayed by atypical presentation, assessment of lumbar puncture safety, and poor sensitivity of standard diagnostic microbiology. Thus, diagnostic dilemmas are common in patients with suspected acute community-acquired bacterial meningitis. History and physical examination alone are sometimes not sufficient to confirm or exclude the diagnosis. Lumbar puncture is an essential investigation, but can be delayed by brain imaging. Results of cerebrospinal fluid (CSF) examination should be interpreted carefully, because CSF abnormalities vary according to the cause, patient's age and immune status, and previous treatment. Diagnostic prediction models that use a combination of clinical findings, with or without test results, can help to distinguish acute bacterial meningitis from other causes, but these models are not infallible. We review the dilemmas in the diagnosis of acute community-acquired bacterial meningitis, and focus on the roles of clinical assessment and CSF examination.

Acoustic wave immunosensing of a meningococcal antigen using gold nanoparticle-enhanced mass sensitivity

Bacterial meningitis is an infection of the thin membranes covering the brain and spinal cord by a number of microorganisms including Neisseria meningitidis, which can lead to permanent neurological damage in the event of late diagnosis. Given the quick onset and severity of the disease, there is a clear need for a rapid, sensitive and specific diagnostic technique. Here, we describe the development and evaluation of an acoustic wave sensor, the quartz crystal microbalance (QCM), as a rapid immunosensor employing antibodies against the cell surface outer membrane protein 85 (OMP85) of N. meningitidis as an immobilized selective layer. These antibodies were directionally orientated as receptors by thin film deposition of structured polyvinylidene fluoride and Protein A. The sensitivity of this QCM immunosensor was further increased by conjugation of the OMP85 antigen to 50 nm gold nanoparticles providing reproducible detection of the target down to 300 ng/mL. Subsequent treatment of the QCM surface with an acidic glycine solution regenerated the immunosensor allowing each crystal to be used several times.

Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis

The epidemiology of bacterial meningitis has changed as a result of the widespread use of conjugate vaccines and preventive antimicrobial treatment of pregnant women. Given the significant morbidity and mortality associated with bacterial meningitis, accurate information is necessary regarding the important etiological agents and populations at risk to ascertain public health measures and ensure appropriate management. In this review, we describe the changing epidemiology of bacterial meningitis in the United States and throughout the world by reviewing the global changes in etiological agents followed by specific microorganism data on the impact of the development and widespread use of conjugate vaccines. We provide recommendations for empirical antimicrobial and adjunctive treatments for clinical subgroups and review available laboratory methods in making the etiological diagnosis of bacterial meningitis. Finally, we summarize risk factors, clinical features, and microbiological diagnostics for the specific bacteria causing this disease.

Neisseria meningitidis: epidemiology, treatment and prevention in adolescents

PURPOSE OF REVIEW

Neisseria meningitidis has been recognized as a cause of serious disease for centuries, but changing epidemiology and advances in treatment and prevention strategies mandate that providers be aware of ongoing developments with regard to this infection. Given the high burden of disease in adolescents, it is important for clinicians to be familiar with current recommendations regarding N. meningitidis.

RECENT FINDINGS

Adolescents and young adults continue to have the second highest incidence of disease from N. meningitidis. New diagnostic techniques, including polymerase chain reaction, have shown promise for enhancing detection of meningococcal infection in selected scenarios. Whereas most isolates of meningococcus remain penicillin-susceptible, fluoroquinolone resistance has now been documented in the US for the first time. Routine immunization using the meningococcal conjugate vaccine continues to be recommended, despite ongoing concern about a possible association between vaccination and Guillain-Barré syndrome. Active research is ongoing to develop a serogroup B vaccine and meningococcal vaccines that are immunogenic in infants and toddlers.

SUMMARY

Given the increased incidence of meningococcal infection among adolescents and the substantial morbidity and mortality associated with invasive disease, adolescent health providers must be familiar with current antibiotic treatment and prophylaxis guidelines and ongoing developments regarding meningococcal vaccination.

Infections with beta-haemolytic streptococci: detection by a universal PCR for bacterial DNA and DNA sequencing

PCR using universal bacterial primers and subsequent DNA sequence analysis of the PCR product was used to detect beta-haemolytic streptococci in clinical samples. Streptococcus pyogenes, Streptococcus agalactiae and Streptococcus dysgalactiae were identified in 19 primary culture-negative cases of infections from 203 patient samples with detectable bacterial DNA.

Fatal ulcerative colitis in a western lowland gorilla (Gorilla gorilla gorilla)

A captive western lowland gorilla (Gorilla gorilla gorilla) presented with watery diarrhoea that progressed to become profuse and haemorrhagic. Faecal analyses revealed Balantidium (B.) coli trophozoites and salmonella-like bacteria. Despite treatment the gorilla died on the 5th day after onset of symptoms. Post-mortem examination revealed a severe erosive-ulcerative superficial and deep colitis. Histological examination of post-mortem samples of the colon showed plentiful B. coli invading into the mucosa and submucosa, whilst PCR screening of bacterial DNA could not confirm any bacteria species which could be connected to the clinical picture. As B. coli is usually a non-pathogenic gut commensal, and as this animal previously showed evidence of non-symptomatic infection of B. coli, it is possible that the switch in pathogenicity was triggered by an acute bacterial infection. Despite successful treatment of the bacterial infection the secondary deep invasion of B. coli was not reversed, possibly because of the failure of the treatment regimen, and led to the death of the gorilla.

Quality assessed nonculture techniques for detection and typing of meningococci

PCR protocols are increasingly used in laboratories worldwide for the diagnosis and confirmation of invasive meningococcal infection. Protocols are now available for the identification of Neisseria meningitidis, for genogrouping, susceptibility to antibiotics and genotyping of the corresponding isolates. The implementation of quality assurance (QA) schemes and standardization of protocols are required. Diagnostic and confirmatory PCRs should perform consistently in clinical and reference microbiology laboratories. General QA schemes address the issues of sample preparation, PCR laboratory environment, equipment and validation of protocols. Moreover, external QA interlaboratory studies are essential. The European Monitoring Group on Meningococci has provided a good forum to conduct such studies through the development and distribution of samples and protocols for nonculture detection and typing of N. meningitidis.