Rapid diagnosis of pneumococcal meningitis: implications for treatment and measuring disease burden

Acute infections of the central nervous system in children and adults: diagnosis and management

Central nervous system infections are due to different microorganisms such as viruses, bacteria, mycobacteria, fungi, amoebas, and other parasites. The etiology depends on multiple risk factors, and it defines the infection location because some microorganisms prefer meninges, brain tissue, cerebellum, brain stem or spinal cord. The microorganisms induce diseases in the nervous system through direct invasion, neurotoxin production, and the triggered immune response. To determine the infection etiology, there are several diagnostic tests which may be conducted with cerebrospinal fluid, blood, respiratory and stool samples. These tests include but are not limited to direct microscopic examination of the sample, stains, cultures, antigenic tests, nucleic acid amplification tests, metagenomic next-generation sequencing, immunologic biomarker and neuroimaging, especially contrast-enhanced magnetic resonance imaging. The treatment may consist of specific antimicrobial treatment and supportive standard care. Since viruses have no specific antiviral treatment, antimicrobial treatment is mainly targeted at non-viral infections. This article will focus on diagnosis and treatment of acute acquired infections of the central nervous system beyond the neonatal period. The discussion defines the disease, provides the clinical presentation, explains the etiology and risk factors, and briefly mentions potential complications. This updated review aims to provide the reader with all the elements needed to adequately approach a patient with a central nervous system infection. Mycobacterium tuberculosis infection, Cryptococcus spp. infection and vaccines are not within the scope of this article.

Effectiveness of ten-valent pneumococcal conjugate vaccine on invasive pneumococcal disease among children <2 years old: A prospective population-based study in rural Bangladesh

The 10-valent pneumococcal conjugate vaccine (PCV10) was introduced in March 2015 in Bangladesh. In this study, we aimed to estimate the impact of PCV10 on invasive pneumococcal disease (IPD) identified by blood cultures and severe pneumonia identified clinically and its effectiveness on invasive disease caused by vaccine serotypes. We conducted population-based surveillance among children aged 2- <24 months between April 2012 through March 2019 in Mirzapur, a rural sub-district of Bangladesh. We compared incidence of IPD and severe pneumonia before (April 2012 to March 2015) and after (April 2015 to March 2019) the introduction of PCV10. Vaccine effectiveness was measured using an indirect cohort analysis of data from four sentinel sites in which PCV10 vaccination status was compared between children with IPD caused by vaccine serotype vs. non-vaccine serotypes. We identified 24 IPD cases by blood culture and 1,704 severe pneumonia hospitalizations during the surveillance period. IPD incidence in under-2-year-old children fell 25 % (95 % CI: -1.2 % to 76 %; p-value = 0.59) from 106 cases per 100,000 child-years at baseline to 79.3 in April 2018- March 2019. Vaccine serotype-IPD incidence was lower (77 % reduction, 95 % CI: -0.45 % to 96 %; p-value = 0.068) in April 2018 - March 2019 than in the pre-vaccine period (85.7 cases to 19.8/100,000 child-years). A significant decline of 54.0 % (95 % CI: 47.0 % to 59.0 %; p-value < 0.001) was observed in hospitalizations due to severe pneumonia. From indirect cohort analysis, the effectiveness of PCV10 against vaccine serotype IPD was 37 % (95 % CI: -141.0 % to 83.5 %; p = 0.5) after the 1st dose and 63.1 % (95 % CI: -3.3 % to 85.9 %, p = 0.0411) after the 2nd or the 3rd dose. This study demonstrates that PCV10 introduction prevented hospitalizations with severe pneumonia and provided individual protection against vaccine serotypes.

Diagnostic accuracy of rapid antigen tests in cerebrospinal fluid for pneumococcal meningitis: a systematic review and meta-analysis

BACKGROUND

Streptococcus pneumoniae is a leading cause of bacterial meningitis worldwide. Conventional microbiological assays take several days and require the use of various drugs for empirical treatment. Rapid antigen tests in cerebrospinal fluid (CSF) may be useful to triage pneumococcal meningitis immediately.

OBJECTIVES

To elucidate whether rapid antigen tests in CSF are useful in the triage of pneumococcal meningitis.

METHODS

Data sourcesCochrane CENTRAL, MEDLINE, EMBASE, World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov databases were searched. Study eligibility criteriaAll types of cohort studies except multiple-group studies, where the sensitivity and specificity of rapid antigen tests in CSF compared with CSF culture can be extracted. ParticipantsPatients with suspected meningitis. TestsRapid antigen tests in CSF. Reference standardsOne or more of the following: blood culture, CSF culture, and polymerase chain reaction in CSF. Assessment of risk of biasThe methodological quality of the included studies was assessed using QUADAS-2. Methods of data synthesisWe used a random-effects bivariate model for the meta-analysis. We conducted a subgroup analysis by dividing studies into types of antigen tests, adults and children, low-income and high-income countries, and with or without exposure to antibiotics before lumbar puncture.

RESULTS

Forty-four studies involving 14 791 participants were included. Most studies had a moderate-to-low methodological quality. Summary sensitivity and specificity were 99.5% (95% confidence interval (CI), 92.4-100%) and 98.2% (95% CI, 96.9-98.9%), respectively. Positive predictive values and negative predictive values at the median prevalence (4.2%) in the included studies were 70.8% (95% CI, 56.6-79.9%) and 100% (95% CI, 99.7-100%), respectively. The diagnostic accuracy was consistent across the various subgroups, except for slightly reduced sensitivity in high-income countries.

CONCLUSIONS

Rapid antigen tests in CSF would be useful in triaging pneumococcal meningitis. Further studies are warranted to investigate the clinical benefit of ruling out pneumococcal meningitis based on the results of rapid antigen tests.

Bacterial meningitis in Africa

Bacterial meningitis differs globally, and the incidence and case fatality rates vary by region, country, pathogen, and age group; being a life-threatening disease with a high case fatality rate and long-term complications in low-income countries. Africa has the most significant prevalence of bacterial meningitis illness, and the outbreaks typically vary with the season and the geographic location, with a high incidence in the meningitis belt of the sub-Saharan area from Senegal to Ethiopia. Streptococcus pneumoniae (pneumococcus) and Neisseria meningitidis (meningococcus) are the main etiological agents of bacterial meningitis in adults and children above the age of one. Streptococcus agalactiae (group B Streptococcus), Escherichia coli, and Staphylococcus aureus are neonatal meningitis's most common causal agents. Despite efforts to vaccinate against the most common causes of bacterial neuro-infections, bacterial meningitis remains a significant cause of mortality and morbidity in Africa, with children below 5 years bearing the heaviest disease burden. The factors attributed to this continued high disease burden include poor infrastructure, continued war, instability, and difficulty in diagnosis of bacterial neuro-infections leading to delay in treatment and hence high morbidity. Despite having the highest disease burden, there is a paucity of African data on bacterial meningitis. In this article, we discuss the common etiologies of bacterial neuroinfectious diseases, diagnosis and the interplay between microorganisms and the immune system, and the value of neuroimmune changes in diagnostics and therapeutics.

Case Report: Persistency Pneumococcal Polysaccharide in Cerebrospinal Fluid During a Post Pneumococcal Chronic Aseptic Meningitis: Coincidental or (Auto-)Inflammatory Embers

We report the case of a 9-months-old boy that has presented a steroid-dependent post-pneumococcal chronic aseptic meningitis was associated with persistence of pneumococcal cell wall components in cerebrospinal fluid during more than 20 months. Suggesting that this antigenic persistence could be involved in post-infectious manifestations through innate immunity response.

Comparison of Culture, Antigen Test, and Polymerase Chain Reaction for Pneumococcal Detection in Cerebrospinal Fluid of Children

Background

Sensitivity of culture for the detection of Streptococcus pneumoniae is limited by prior antibiotic exposure. Immunochromatographic test (ICT) is highly sensitive and specific for pneumococcal antigen detection in the cerebrospinal fluid (CSF) of meningitis cases. We determined the specificity and sensitivity of culture, ICT, and polymerase chain reaction (PCR) and the effect of antibiotic exposure on their performance.

Methods

CSF specimens from suspected meningitis cases admitted to Dhaka Shishu Hospital, Bangladesh, were tested using culture, ICT and PCR. Additionally, 165 specimens collected from 69 pneumococcal cases after antibiotic treatment were tested.

Results

Of 1883 specimens tested, culture detected 9, quantitative PCR (qPCR) detected 184, and ICT detected 207 pneumococcal cases (including all culture and qPCR positives). In comparison to ICT, sensitivity of culture was 4.4% and of qPCR was 90.6%; both were 100% specific. After antibiotic exposure, culture sensitivity plummeted rapidly; conventional PCR and qPCR sensitivity disappeared after day 6 and 20, respectively. ICT detected pneumococcal antigen for >10 weeks.

Conclusions

While culture provides the most information about bacterial characteristics, in high antibiotic exposure settings, ICT exhibits maximum sensitivity. We recommend culture and ICT as mainstay for pneumococcal diagnosis and surveillance; qPCR can generate additional molecular data where possible.

Case Report: Prolonged CSF PCR Positivity in a Neonate With GBS Meningitis

Bacterial meningitis is one of the critical diseases that needs to be diagnosed and treated promptly. Recent diagnostics of high sensitivity and specificity rates, such as PCR, helped with such presentation, especially in cases with prior antibiotics that led to culture negativity. However, the time window of PCR positivity is not well-studied, with scattered reports of different periods of positivity. Here, we report a case of neonatal GBS meningitis with positive PCR for more than 80 days from starting antibiotics.

Management of Acute Bacterial Meningitis in Children

Acute community-acquired bacterial meningitis (ABM) in children continues to have high rates of neurological morbidity and mortality despite the overall declining rates of infection attributed to the use of vaccines and intrapartum Group B Streptococcus prophylaxis. Prompt diagnosis and early antibiotic therapy are crucial and should not be delayed to obtain cranial imaging. Differentiating bacterial from viral meningitis continues to be a clinical dilemma especially in patients with previous antibiotic exposure. Clinical models and inflammatory biomarkers can aid clinicians in their diagnostic approach. Multiplex polymerase chain reaction and metagenomic next-generation sequencing are promising tools that can help in early and accurate diagnosis. This review will present the epidemiology of ABM in children, indications of cranial imaging, role of different models and serum biomarkers in diagnosing ABM, and management including the use of adjunctive therapies and methods of prevention.

Identification of Widespread Antibiotic Exposure in Patients With Cholera Correlates With Clinically Relevant Microbiota Changes

BACKGROUND

A first step to combating antimicrobial resistance in enteric pathogens is to establish an objective assessment of antibiotic exposure. Our goal was to develop and evaluate a liquid chromatography-ion trap mass spectrometry (LC/MS) method to determine antibiotic exposure in patients with cholera.

METHODS

A priority list for targeted LC/MS was generated from medication-vendor surveys in Bangladesh. A study of patients with and those without cholera was conducted to collect and analyze paired urine and stool samples.

RESULTS

Among 845 patients, 11% (90) were Vibrio cholerae positive; among these 90 patients, analysis of stool specimens revealed ≥1 antibiotic in 86% and ≥2 antibiotics in 52%. Among 44 patients with cholera and paired urine and stool specimens, ≥1 antibiotic was detected in 98% and ≥2 antibiotics were detected in 84%, despite 55% self-reporting medication use. Compared with LC/MS, a low-cost antimicrobial detection bioassay lacked a sufficient negative predictive value (10%; 95% confidence interval, 6%-16%). Detection of guideline-recommended antibiotics in stool specimens did (for azithromycin; P = .040) and did not (for ciprofloxacin) correlate with V. cholerae suppression. A nonrecommended antibiotic (metronidazole) was associated with decreases in anaerobes (ie, Prevotella organisms; P < .001).

CONCLUSION

These findings suggest that there may be no true negative control group when attempting to account for antibiotic exposure in settings like those in this study.

Unbiased Metagenomic Sequencing for Pediatric Meningitis in Bangladesh Reveals Neuroinvasive Chikungunya Virus Outbreak and Other Unrealized Pathogens

Globally, there are an estimated 10.6 million cases of meningitis and 288,000 deaths every year, with the vast majority occurring in low- and middle-income countries. In addition, many survivors suffer from long-term neurological sequelae. Most laboratories assay only for common bacterial etiologies using culture and directed PCR, and the majority of meningitis cases lack microbiological diagnoses, impeding institution of evidence-based treatment and prevention strategies. We report here the results of a validation and application study of using unbiased metagenomic sequencing to determine etiologies of idiopathic (of unknown cause) cases. This included CSF from patients with known neurologic infections, with idiopathic meningitis, and without infection admitted in the largest children’s hospital of Bangladesh and environmental samples. Using mNGS and machine learning, we identified and confirmed an etiology (viral or bacterial) in 40% of idiopathic cases. We detected three instances of Chikungunya virus (CHIKV) that were >99% identical to each other and to a strain previously recognized to cause systemic illness only in 2017. CHIKV qPCR of all remaining stored 472 CSF samples from children who presented with idiopathic meningitis in 2017 at the same hospital uncovered an unrecognized CHIKV meningitis outbreak. CSF mNGS can complement conventional diagnostic methods to identify etiologies of meningitis, and the improved patient- and population-level data can inform better policy decisions.

The burden of meningitis in low-and-middle-income countries remains significant, but the infectious causes remain largely unknown, impeding institution of evidence-based treatment and prevention decisions. We conducted a validation and application study of unbiased metagenomic next-generation sequencing (mNGS) to elucidate etiologies of meningitis in Bangladesh. This RNA mNGS study was performed on cerebrospinal fluid (CSF) specimens from patients admitted in the largest pediatric hospital, a World Health Organization sentinel site, with known neurologic infections (n = 36), with idiopathic meningitis (n = 25), and with no infection (n = 30), and six environmental samples, collected between 2012 and 2018. We used the IDseq bioinformatics pipeline and machine learning to identify potentially pathogenic microbes, which we then confirmed orthogonally and followed up through phone/home visits. In samples with known etiology and without infections, there was 83% concordance between mNGS and conventional testing. In idiopathic cases, mNGS identified a potential bacterial or viral etiology in 40%. There were three instances of neuroinvasive Chikungunya virus (CHIKV), whose genomes were >99% identical to each other and to a Bangladeshi strain only previously recognized to cause febrile illness in 2017. CHIKV-specific qPCR of all remaining stored CSF samples from children who presented with idiopathic meningitis in 2017 (n = 472) revealed 17 additional CHIKV meningitis cases, exposing an unrecognized meningitis outbreak. Orthogonal molecular confirmation, case-based clinical data, and patient follow-up substantiated the findings. Case-control CSF mNGS surveys can complement conventional diagnostic methods to identify etiologies of meningitis, conduct surveillance, and predict outbreaks. The improved patient- and population-level data can inform evidence-based policy decisions.

Invasive Pneumococcal Infections in Children with Nephrotic Syndrome in Bangladesh

INTRODUCTION

Children with nephrotic syndrome are susceptible to invasive bacterial infections. In this study, we aimed to: (1) determine the pathogens associated with infections in children with nephrotic syndrome and (2) describe antimicrobial susceptibility and serotype distribution of Streptococcus pneumoniae to guide evidence-based treatment and prevention policies.

METHODS

From June 2013 to March 2015, we collected blood and/or ascitic fluid from children hospitalized with nephrotic syndrome and suspected bacterial disease in the largest pediatric hospital of Bangladesh. We cultured all samples and performed polymerase chain reaction (PCR) and immunochromatographic test on ascitic fluid for detection of S. pneumoniae. Pneumococcal isolates were tested for antibiotic susceptibility using disc diffusion and serotyped using Quellung reaction and PCR.

RESULTS

We identified 1342 children hospitalized with nephrotic syndrome. Among them, 608 children had suspected bacterial disease from whom blood and/or ascitic fluid were collected. A pathogen was identified in 8% (48/608) of cases, 94% (45/48) of which were S. pneumoniae. Most (73%, 33/45) pneumococcal infections were identified through culture of blood and ascitic fluid and 27% (12/45) through immunochromatographic test and PCR of ascitic fluid. In total, 24 different pneumococcal serotypes were detected; 51% are covered by PCV10 (+6A), 53% by PCV13 and 60% by PPSV23. All pneumococcal isolates were susceptible to penicillin.

CONCLUSIONS

Because S. pneumoniae was the primary cause of invasive infections, pneumococcal vaccines may be considered as a preventive intervention in children with nephrotic syndrome. Additionally, penicillin can be used to prevent and treat pneumococcal infections in children with nephrotic syndrome in Bangladesh.

The etiology of acute meningitis and encephalitis syndromes in a sentinel pediatric hospital, Shenzhen, China

Background

Acute meningitis and encephalitis syndromes (AMES) is a severe neurological infection which causes high case fatality and severe sequelae in children. To determine the etiology of childhood AMES in Shenzhen, a hospital-based study was undertaken.

Methods

A total of 240 cerebrospinal fluid (CSF) samples from 171 children meeting the case definition were included and screened for 12 common causative organisms. The clinical data and conventional testing results were collected and analyzed. Whole genome sequencing was performed on a Neisseria meningitidis isolate.

Results

A pathogen was found in 85 (49.7%) cases; Group B Streptococcus (GBS) was detected in 17 cases, Escherichia coli in 15, Streptococcus pneumoniae in 14, enterovirus (EV) in 13, herpes simplex virus (HSV) in 3, N. meningitidis in 1, Haemophilus influenzae in 1, and others in 23. Notably, HSV was found after 43 days of treatment. Twelve GBS and 6 E. coli meningitis were found in neonates aged less than 1 month; 13 pneumococcal meningitis in children aged > 3 months; and 12 EV infections in children aged > 1 year old. The multilocus sequence typing of serogroup B N. meningitidis isolate was ST-3200/CC4821. High resistance rate to tetracycline (75%), penicillin (75%), and trimethoprim/sulfamethoxazole (75%) was found in 4 of S. pneumoniae isolates; clindamycin (100%) and tetracycline (100%) in 9 of GBS; and ampicillin (75%) and trimethoprim/sulfamethoxazole (67%) in 12 of E. coli.

Conclusions

The prevalence of N. meningitidis and JEV was very low and the cases of childhood AMES were mainly caused by other pathogens. GBS and E. coli were the main causative organisms in neonates, while S. pneumoniae and EV were mainly found in older children. HSV could be persistently found in the CSF samples despite of the treatment. A better prevention strategy for GBS, the introduction of pneumococcal vaccine, and incorporation of PCR methods were recommended.

Diagnosis of bacterial meningitis in Ghana: Polymerase chain reaction versus latex agglutination methods

Bacterial meningitis is a public health crisis in the northern part of Ghana, where it contributes to very high mortality and morbidity rates. Early detection of the causative organism will lead to better management and effective treatment. Our aim was to evaluate the diagnostic accuracy of Pastorex and Wellcogen latex agglutination tests for the detection of bacterial meningitis in a resource-limited setting. CSF samples from 330 suspected meningitis patients within the northern zone of Ghana were analysed for bacterial agents at the zonal Public Health Reference Laboratory in Tamale using polymerase chain reaction (PCR) and two latex agglutination test kits; Pastorex and Wellcogen. The overall positivity rate of samples tested for bacterial meningitis was 46.4%. Streptococcus pneumoniae was the most common cause of bacterial meningitis within the sub-region, with positivity rate of 25.2%, 28.2% and 28.8% when diagnosed using Wellcogen, Pastorex and PCR respectively. The Pastorex method was 97.4% sensitive while the Wellcogen technique was 87.6% sensitive. Both techniques however produced the same specificity of 99.4%. Our study revealed that the Pastorex method has a better diagnostic value for bacterial meningitis than the Wellcogen method and should be the method of choice in the absence of PCR.

Spontaneous pneumococcal peritonitis diagnosed by qPCR

Spontaneous bacterial peritonitis is an uncommon manifestation of invasive pneumococcal disease and frequently occurs when an underlying hepatic disease is present. Bacterial identification through culture can be particularly challenging in patients with prior or concurrent antimicrobial use. DNA amplification detects very few copies of target DNA under ideal conditions in CSF or pleural effusion and, therefore, can be useful in selected infections. A culture-negative spontaneous pneumococcal peritonitis without preexisting peritoneal disease diagnosed by qPCR is herein described.

Evaluating PCR-Based Detection of Salmonella Typhi and Paratyphi A in the Environment as an Enteric Fever Surveillance Tool

With prequalification of a typhoid conjugate vaccine by the World Health Organization, countries are deciding whether and at what geographic scale to provide the vaccine. Optimal local data to clarify typhoid risk are expensive and often unavailable. To determine whether quantitative polymerase chain reaction (qPCR) can be used as a tool to detect typhoidal Salmonella DNA in the environment and approximate the burden of enteric fever, we tested water samples from urban Dhaka, where enteric fever burden is high, and rural Mirzapur, where enteric fever burden is low and sporadic. Sixty-six percent (38/59) of the water sources of Dhaka were contaminated with typhoidal Salmonella DNA, in contrast to none of 33 samples of Mirzapur. If these results can be replicated in larger scale in Bangladesh and other enteric fever endemic areas, drinking water testing could become a low-cost approach to determine the presence of typhoidal Salmonella in the environment that can, in turn, guide informed-design of blood culture-based surveillance and thus assist policy decisions on investing to control typhoid.

Invasive Streptococcus pneumoniae infection among hospitalized patients in Jingzhou city, China, 2010-2012

BACKGROUND

Streptococcus pneumoniae (Sp) is a leading cause of bacterial pneumonia, meningitis, and sepsis and a major source of morbidity and mortality worldwide. Invasive pneumococcal disease (IPD) is defined as isolation of Sp from a normally sterile site, including blood or cerebrospinal fluid. The aim of this study is to describe outcomes as well as clinical and epidemiological characteristics of hospitalized IPD case patients in central China.

METHODS

We conducted surveillance for IPD among children and adults from April 5, 2010 to September 30, 2012, in four major hospitals in Jingzhou City, Hubei Province. We collected demographic, clinical, and outcome data for all enrolled hospitalized patients with severe acute respiratory infection (SARI) or meningitis, and collected blood, urine, and cerebrospinal fluid (CSF) for laboratory testing for Sp infections. Collected data were entered into Epidata software and imported into SPSS for analysis.

RESULTS

We enrolled 22,375 patients, including 22,202 (99%) with SARI and 173 (1%) with meningitis. One hundred and eighteen (118, 3%) with either SARI or meningitis were Sp positive, 32 (0.8%) from blood/CSF culture, and 87 (5%) from urine antigen testing. Of those 118 patients, 57% were aged ≥65 years and nearly 100% received antibiotics during hospitalization. None were previously vaccinated with 7-valent pneumococcal conjugate vaccine (PCV 7), 23-valent pneumococcal polysaccharide vaccine, or seasonal influenza vaccine. The main serotypes identified were 14, 12, 3, 1, 19F, 4, 5, 9V, 15 and 18C, corresponding to serotype coverage rates of 42%, 63%, and 77% for PCV7, PCV10, and PCV13, respectively.

CONCLUSIONS

Further work is needed to expand access to pneumococcal vaccination in China, both among children and potentially among the elderly, and inappropriate use of antibiotics is a widespread and serious problem in China.

Community-acquired bacterial meningitis

Meningitis is an inflammation of the meninges and subarachnoid space that can also involve the brain cortex and parenchyma. It can be acquired spontaneously in the community - community-acquired bacterial meningitis - or in the hospital as a complication of invasive procedures or head trauma (nosocomial bacterial meningitis). Despite advances in treatment and vaccinations, community-acquired bacterial meningitis remains one of the most important infectious diseases worldwide. Streptococcus pneumoniae and Neisseria meningitidis are the most common causative bacteria and are associated with high mortality and morbidity; vaccines targeting these organisms, which have designs similar to the successful vaccine that targets Haemophilus influenzae type b meningitis, are now being used in many routine vaccination programmes. Experimental and genetic association studies have increased our knowledge about the pathogenesis of bacterial meningitis. Early antibiotic treatment improves the outcome, but the growing emergence of drug resistance as well as shifts in the distribution of serotypes and groups are fuelling further development of new vaccines and treatment strategies. Corticosteroids were found to be beneficial in high-income countries depending on the bacterial species. Further improvements in the outcome are likely to come from dampening the host inflammatory response and implementing preventive measures, especially the development of new vaccines.

Pneumococcal Disease in the Era of Pneumococcal Conjugate Vaccine

Universal immunization of infants and toddlers with pneumococcal conjugate vaccines over the last 15 years has dramatically altered the landscape of pneumococcal disease. Decreases in invasive pneumococcal disease, all-cause pneumonia, empyema, mastoiditis, acute otitis media, and complicated otitis media have been reported from multiple countries in which universal immunization has been implemented. Children with comorbid conditions have higher rates of pneumococcal disease and increased case fatality rates compared with otherwise healthy children, and protection for the most vulnerable pediatric patients will require new strategies to address the underlying host susceptibility and the expanded spectrum of serotypes observed.

Epidemiology of Invasive Pneumococcal Disease in Bangladeshi Children Before Introduction of Pneumococcal Conjugate Vaccine

BACKGROUND

Because Bangladesh intended to introduce pneumococcal conjugate vaccine (PCV)-10 in 2015, we examined the baseline burden of invasive pneumococcal disease (IPD) to measure impact of PCV.

METHODS

During 2007-2013, we performed blood and cerebrospinal fluid cultures in children <5 years old with suspected IPD identified through active surveillance at 4 hospitals. Isolates were serotyped by quellung and tested for antibiotic susceptibility by disc diffusion and E-test. Serotyping of culture-negative cases, detected by Binax or polymerase chain reaction, was done by sequential multiplex polymerase chain reaction. Trends in IPD case numbers were analyzed by serotype and clinical syndrome.

RESULTS

The study identified 752 IPD cases; 78% occurred in children <12 months old. Serotype information was available for 78% (442/568), including 197 of 323 culture-negative cases available for serotyping. We identified 50 serotypes; the most common serotypes were 2 (16%), 1 (10 %), 6B (7%), 14 (7%) and 5 (7%). PCV-10 and PCV-13 serotypes accounted for 46% (range 29%-57% by year) and 50% (range 37%-64% by year) of cases, respectively. Potential serotype coverage for meningitis and nonmeningitis cases was 45% and 49% for PCV-10, and 48% and 57% for PCV-13, respectively. Eighty-two percent of strains were susceptible to all antibiotics except cotrimoxazole.

CONCLUSION

The distribution of serotypes causing IPD in Bangladeshi children is diverse, limiting the proportion of IPD cases PCV can prevent. However, PCV introduction is expected to have major benefits as the country has a high burden of IPD-related mortality, morbidity and disability.

Enhanced Diagnosis of Pneumococcal Bacteremia Using Antigen- and Molecular-Based Tools on Blood Specimens in Mali and Thailand: A Prospective Surveillance Study

Prior antibiotic use, contamination, limited blood volume, and processing delays reduce yield of blood cultures for detection of Streptococcus pneumoniae. We performed immunochromatographic testing (ICT) on broth from incubated blood culture bottles and real-time lytA polymerase chain reaction (PCR) on broth and whole blood and compared findings to blood culture in patients with suspected bacteremia. We selected 383 patients in Mali and 586 patients in Thailand based on their blood culture results: 75 and 31 were positive for pneumococcus, 100 and 162 were positive for other pathogens, and 208 and 403 were blood culture negative, respectively. ICT and PCR of blood culture broth were at least 87% sensitive and 97% specific compared with blood culture; whole blood PCR was 75–88% sensitive and 96–100% specific. Pneumococcal yields in children < 5 years of age increased from 2.9% to 10.7% in Mali with > 99% of additional cases detected by whole blood PCR, and from 0.07% to 5.1% in Thailand with two-thirds of additional cases identified by ICT. Compared with blood culture, ICT and lytA PCR on cultured broth were highly sensitive and specific but their ability to improve pneumococcal identification varied by site. Further studies of these tools are needed before widespread implementation.

Time window for positive cerebrospinal fluid broad-range bacterial PCR and Streptococcus pneumoniae immunochromatographic test in acute bacterial meningitis

BACKGROUND

Reliable microbiological tests are essential for the diagnosis of acute bacterial meningitis (ABM). In this study we investigated the time period after the start of antibiotic therapy during which culture, polymerase chain reaction (PCR) and the immunochromatographic test (ICT) are able to detect bacteria in cerebrospinal fluid (CSF).

METHODS

The study was performed on CSF samples from adults with ABM admitted to the Department of Infectious Diseases, Sahlgrenska University Hospital, Gothenburg, Sweden, from January 2007 to April 2014. In addition to the initial lumbar puncture (LP), the participants underwent one or two more LPs during 10 days following the start of antibiotics. The analyses performed on the CSF samples were culture, PCR and ICT.

RESULTS

The study comprised 70 CSF samples from 25 patients with ABM. A bacterium could be identified by CSF culture in 44%, by blood culture in 58% and by PCR in 100% of the patients. There were no positive CSF cultures in samples taken later than the day of starting antibiotics. PCR was positive in 89% on days 1-3, 70% on days 4-6 and 33% on days 7-10. For cases of pneumococcal meningitis, the ICT was positive in 88% on days 1-3, 90% on days 4-6 and 75% on days 7-10.

CONCLUSIONS

This study shows that PCR is highly sensitive for bacterial detection in CSF samples taken up to 1 week into antibiotic therapy. The ICT is highly sensitive for the detection of pneumococci in CSF samples taken during the first week of antibiotic treatment.

Comparative study of bacteriological culture and real-time fluorescence quantitative PCR (RT-PCR) and multiplex PCR-based reverse line blot (mPCR/RLB) hybridization assay in the diagnosis of bacterial neonatal meningitis

Background

Bacterial meningitis is more common in the neonatal period than any other time in life; however, it is still a challenge for the evidence based diagnosis. Strategy for identification of neonatal bacterial meningitis pathogens is presented by evaluating three different available methods to establish evidence-based diagnosis for neonatal bacterial meningitis.

Methods

The cerebrospinal fluid samples from 56 neonates diagnosed as bacterial meningitis in 2009 in Beijing Children’s Hospital were analyzed in the study. Two PCR based molecular assays, real-time fluorescence quantitative PCR (RT-PCR) and multiplex PCR based-reverse line blot hybridization (mPCR/RLB), were used to assess 7 common neonatal meningitis bacterial pathongens, including Escherichia coli, Staphylococcus aureus, Listerisa monocytogenes, Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae, and Streptococcus agalactiae. The findings in examinations of two assays were compared with the results obtained bacterial culture tests.

Results

Bacterial meningitis was identified in five cases (9%) by CSF cultures, 25 (45%) by RT-PCR and 16 (29%) by mPCR/RLB. One strain of S. epidermidis and one of E. faecalis were identified using mPCR/RLB but not by RT-PCR. In contrast, cultures identified one strain of S. pneumoniae which was missed by both PCR assays. Overall, the bacterial pathogens in 28 cases were identified with these three methods. Both RT-PCR and mPCR/RLB assays were more sensitive than bacterial culture, (p < 0.05).

Conclusion

Our study confirmed that both RT-PCR and mPCR/RLB assays have better sensitivity than bacterial culture. They are capable of detecting the pathogens in CSF samples with negative culture results.

Follow-up of cases of Haemophilus influenzae type b meningitis to determine its long-term sequelae

OBJECTIVE

To measure physical and neurologic impact of Haemophilus influenzae type b (Hib) meningitis on surviving children through short- and long-term follow-up.

STUDY DESIGN

Cases of Hib meningitis, diagnosed at a tertiary level pediatric hospital, were subjected to short- and long-term follow-up and compared with age, sex, and area of residence matched healthy controls. Follow-up assessments included thorough physical and neurodevelopmental assessments using a standardized protocol by a multidisciplinary team.

RESULTS

Assessments of short-term follow-up cohort (n = 64) revealed hearing, vision, mental, and psychomotor deficits in 7.8%, 3%, 20%, and 25% of the cases, respectively. Deficits were 10%, 1.4%, 21%, and 25% in long-term follow-up cohort (n = 71), in that order. Mental and psychomotor deficits were found in 2% of the controls, none of whom had vision or hearing deficits.

CONCLUSIONS

In addition to risk of death, Hib meningitis in children causes severe disabilities in survivors. These data facilitated a comprehensive understanding of the burden of Hib meningitis, specifically in developing countries where disabled children remain incapacitated because of lack of resources and facilities. The evidence generated from this study is expected to provide a compelling argument in favor of introduction and continuation of Hib conjugate vaccine in the national immunization program for children.

Rapid diagnostic tests for neurological infections in central Africa

Infections are a leading cause of life-threatening neuropathology worldwide. In central African countries affected by endemic diseases such as human African trypanosomiasis, tuberculosis, HIV/AIDS, and schistosomiasis, delayed diagnosis and treatment often lead to avoidable death or severe sequelae. Confirmatory microbiological and parasitological tests are essential because clinical features of most neurological infections are not specific, brain imaging is seldom feasible, and treatment regimens are often prolonged or toxic. Recognition of this diagnostic bottleneck has yielded major investment in application of advances in biotechnology to clinical microbiology in the past decade. We review the neurological pathogens for which rapid diagnostic tests are most urgently needed in central Africa, detail the state of development of putative rapid diagnostic tests for each, and describe key technical and operational challenges to their development and implementation. Promising field-suitable rapid diagnostic tests exist for the diagnosis of human African trypanosomiasis and cryptococcal meningoencephalitis. For other infections-eg, syphilis and schistosomiasis-highly accurate field-validated rapid diagnostic tests are available, but their role in diagnosis of disease with neurological involvement is still unclear. For others-eg, tuberculosis-advances in research have not yet yielded validated tests for diagnosis of neurological disease.

Laboratory diagnosis of CNS infections by molecular amplification techniques

The initial presentation of symptoms and clinical manifestations of CNS infectious diseases often makes a specific diagnosis difficult and uncertain, and the emergence of polymerase chain reaction-led molecular techniques have been used in improving organism-specific diagnosis. These techniques have not only provided rapid, non-invasive detection of microorganisms causing CNS infections, but also demonstrated several neurologic disorders linked to infectious pathogens. Molecular methods performed on cerebrospinal fluid are recognized as the new 'gold standard' for some of these infections caused by microorganisms that are difficult to detect and identify. Although molecular techniques are predicted to be widely used in diagnosing and monitoring CNS infections, the limitations as well as strengths of these techniques must be clearly understood by both clinicians and laboratory personnel.

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.

Future challenges in the elimination of bacterial meningitis

Despite the widespread implementation of several effective vaccines over the past few decades, bacterial meningitis caused by Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis and Group B Streptococcus (GBS) still results in unacceptably high levels of human mortality and morbidity. A residual disease burden due to bacterial meningitis is also apparent due to a number of persistent or emerging pathogens, including Mycobacterium tuberculosis, Escherichia coli, Staphylococcus aureus, Salmonella spp. and Streptococcus suis. Here, we review the current status of bacterial meningitis caused by these pathogens, highlighting how past and present vaccination programs have attempted to counter these pathogens. We discuss how improved pathogen surveillance, implementation of current vaccines, and development of novel vaccines may be expected to further reduce bacterial meningitis and related diseases in the future.

Pleural fluid nucleic acid testing enhances pneumococcal surveillance in children

BACKGROUND AND OBJECTIVE

National surveillance of invasive pneumococcal disease (IPD) includes serotyping Streptococcus pneumoniae (SP) isolates from sterile site cultures. PCR is more sensitive and can identify more SP serotypes (STs) in culture-negative samples. The aim of this study was to determine whether enhanced surveillance of childhood empyema, using PCR, provides additional serotype information compared with conventional surveillance.

METHODS

Pleural fluid (PF) from children with empyema were cultured and tested by PCR to identify SP, targeting the autolysin gene (lytA). Multiplex PCR-based reverse line blot assay was used to identify SP STs. Corresponding IPD surveillance and serotype data were obtained from the National Notifiable Diseases Surveillance System (NNDSS).

RESULTS

Eighty-nine children with empyema, aged ≤16 years, were recruited between April 2008 and March 2009, inclusive. SP was isolated from 5/84 (5.9%) PF cultures and by PCR in 43/79 (54.4%) PF samples. Serotypes were unidentifiable in 15 samples. The frequency of six serotypes (or serotype pairs) identified in 28 samples, including one with two serotypes, were: ST1, n = 4/29 (13.8%); ST3, n = 9/29 (31.0%); ST19A, n = 12/29 (41.4%); ST7F/7A, n = 1/29 (3.4%); ST9V/9A, n = 1/29 (3.4%); ST22F/22A, n = 2/29 (6.9%). Over the same period, 361 IPD patients, aged 16 years or less, were notified to NNDSS. Among 331 serotypeable NNDSS isolates (71.5% from blood), the frequencies of ST1 and 3 were significantly lower than in PF samples: ST1, n = 8/331 (2.4%; P < 0.05); ST3, n = 13/331 (3.9%; P < 0.0001).

CONCLUSIONS

The use of PCR to identify and serotype SP in culture-negative specimens provides additive information.

Incorporation of real-time PCR into routine public health surveillance of culture negative bacterial meningitis in São Paulo, Brazil

Real-time (RT)-PCR increases diagnostic yield for bacterial meningitis and is ideal for incorporation into routine surveillance in a developing country. We validated a multiplex RT-PCR assay for Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae in Brazil. Risk factors for being culture-negative, RT-PCR positive were determined. The sensitivity of RT-PCR in cerebrospinal fluid (CSF) was 100% (95% confidence limits, 96.0%-100%) for N. meningitidis, 97.8% (85.5%-99.9%) for S. pneumoniae, and 66.7% (9.4%-99.2%) for H. influenzae. Specificity ranged from 98.9% to 100%. Addition of RT-PCR to routine microbiologic methods increased the yield for detection of S. pneumoniae, N. meningitidis, and H. influenzae cases by 52%, 85%, and 20%, respectively. The main risk factor for being culture negative and RT-PCR positive was presence of antibiotic in CSF (odds ratio 12.2, 95% CI 5.9-25.0). RT-PCR using CSF was highly sensitive and specific and substantially added to measures of meningitis disease burden when incorporated into routine public health surveillance in Brazil.

Improving the sensitivity of blood culture for Streptococcus pneumoniae

Isolation of Streptococcus pneumoniae is jeopardized by low sensitivity of blood culture, autolysis and contamination with fast-growing organism(s). We performed an immunochromatographic (ICT) test for S. pneumoniae on chocolatized blood culture bottles and also sub-cultured contaminated bottles on a selective medium, thus identifying an additional eight and three cases, respectively, and improving the detection of pneumococcus by 23% (48% vs. 59%). Prescreening of culture bottles in a blinded fashion could rationalize the use of ICT with ~99% accuracy. These two approaches can aid microbiology laboratories in resource-poor countries to substantially improve rates of detection of S. pneumoniae.

Bacterial meningitis: epidemiology, pathogenesis and management update

Bacterial meningitis continues to be an important disease throughout the world and can be a life-threatening emergency if not suspected, appropriately diagnosed and managed expeditiously. The epidemiology of bacterial meningitis has changed dramatically over the last 20 years, primarily as a result of the introduction of conjugate vaccines against the common meningeal pathogens, such that in the developed world where vaccination is routinely utilized, bacterial meningitis has become a disease of adults rather than of infants and children. The management approach to patients with suspected or proven bacterial meningitis includes emergent cerebrospinal fluid analysis and initiation of appropriate antimicrobial and adjunctive therapies. The choice of empirical antimicrobial therapy is based on the patient's age and underlying disease status; once the infecting pathogen is isolated, antimicrobial therapy can be modified for optimal treatment. Many patients with suspected or proven bacterial meningitis should also receive adjunctive dexamethasone therapy. This is based on experimental animal model data which demonstrated that the subarachnoid space inflammatory response that results from antimicrobial-induced bacterial lysis can contribute to morbidity and mortality. Clinical studies have demonstrated the benefit of adjunctive dexamethasone in infants and children with Haemophilus influenzae type B meningitis, and adults with pneumococcal meningitis, in which mortality and adverse outcome are reduced. Use of adjunctive dexamethasone in adults with meningitis caused by other bacteria, and in infants and children with pneumococcal meningitis, is controversial. To be effective, adjunctive dexamethasone should be administered concomitant with or just prior to the first antimicrobial dose for maximal effect on the subarachnoid space inflammatory response.

Acute bacterial meningitis in infants and children

Bacterial meningitis continues to be an important cause of mortality and morbidity in neonates and children throughout the world. The introduction of the protein conjugate vaccines against Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis has changed the epidemiology of bacterial meningitis. Suspected bacterial meningitis is a medical emergency and needs empirical antimicrobial treatment without delay, but recognition of pathogens with increasing resistance to antimicrobial drugs is an important factor in the selection of empirical antimicrobial regimens. At present, strategies to prevent and treat bacterial meningitis are compromised by incomplete understanding of the pathogenesis. Further research on meningitis pathogenesis is thus needed. This Review summarises information on the epidemiology, pathogenesis, new diagnostic methods, empirical antimicrobial regimens, and adjunctive treatment of acute bacterial meningitis in infants and children.

[Contribution of microbiological methods to the diagnosis of acute bacterial meningitis]

The most frequent bacteria responsible for acute bacterial meningitis, after the neonatal period, are meningoccoci and pneumococci, very rarely Haemophilus influenzae and Listeria monocytogenes. The microbiological diagnosis is based on cell count, Gram stain, and culture of cerebrospinal fluid. Antigen detection and DNA detection are useful to identify the bacteria in cases of negative cultures, because of the fragility of some bacterial species (meningococci), or a prior antibiotic administration, before a lumbar puncture. Some tests for screening antimicrobial resistances are needed, such as those for detection of resistance to betalactam agents in pneumococcal isolates. Blood cultures, serum samples, skin rash biopsies also contribute to the diagnosis.

Enhanced diagnosis of pneumococcal meningitis with use of the Binax NOW immunochromatographic test of Streptococcus pneumoniae antigen: a multisite study

BACKGROUND

Accurate etiological diagnosis of meningitis in developing countries is needed, to improve clinical care and to optimize disease-prevention strategies. Cerebrospinal fluid (CSF) culture and latex agglutination testing are currently the standard diagnostic methods but lack sensitivity.

METHODS

We prospectively assessed the utility of an immunochromatographic test (ICT) of pneumococcal antigen (NOW Streptococcus pneumoniae Antigen Test; Binax), compared with culture, in 5 countries that are conducting bacterial meningitis surveillance in Africa and Asia. Most CSF samples were collected from patients aged 1-59 months.

RESULTS

A total of 1173 CSF samples from suspected meningitis cases were included. The ICT results were positive for 68 (99%) of the 69 culture-confirmed pneumococcal meningitis cases and negative for 124 (99%) of 125 culture-confirmed bacterial meningitis cases caused by other pathogens. By use of culture and latex agglutination testing alone, pneumococci were detected in samples from 7.4% of patients in Asia and 15.6% in Africa. The ICT increased pneumococcal detection, resulting in similar identification rates across sites, ranging from 16.2% in Nigeria to 20% in Bangladesh. ICT detection in specimens from culture-negative cases varied according to region (8.5% in Africa vs. 18.8% in Asia; P< .001), prior antibiotic use (24.2% with prior antibiotic use vs. 12.2% without; P< .001), and WBC count (9.0% for WBC count of 10-99 cells/mL, 22.1% for 100-999 cells/mL, and 25.4% for >or=1000 cells/mL; P< .001 by test for trend).

CONCLUSIONS

The ICT provided substantial benefit over the latex agglutination test and culture at Asian sites but not at African sites. With the addition of the ICT, the proportion of meningitis cases attributable to pneumococci was determined to be similar in Asia and Africa. These results suggest that previous studies have underestimated the proportion of pediatric bacterial meningitis cases caused by pneumococci.

Identification of serotype in culture negative pneumococcal meningitis using sequential multiplex PCR: implication for surveillance and vaccine design

Background

PCR-based serotyping of Streptococcus pneumoniae has been proposed as a simpler approach than conventional methods, but has not been applied to strains in Asia where serotypes are diverse and different from other part of the world. Furthermore, PCR has not been used to determine serotype distribution in culture-negative meningitis cases.

Methodology

Thirty six serotype-specific primers, 7 newly designed and 29 previously published, were arranged in 7 multiplex PCR sets, each in new hierarchies designed for overall serotype distribution in Bangladesh, and specifically for meningitis and non-meningitis isolates. Culture-negative CSF specimens were then tested directly for serotype-specific sequences using the meningitis-specific set of primers. PCR-based serotyping of 367 strains of 56 known serotypes showed 100% concordance with quellung reaction test. The first 7 multiplex reactions revealed the serotype of 40% of all, and 31% and 48% non-meningitis and meningitis isolates, respectively. By redesigning the multiplex scheme specifically for non-meningitis or meningitis, the quellung reaction of 43% and 48% of respective isolates could be identified. Direct examination of 127 culture-negative CSF specimens, using the meningitis-specific set of primers, yielded serotype for 51 additional cases.

Conclusions

This PCR approach, could improve ascertainment of pneumococcal serotype distributions, especially for meningitis in settings with high prior use of antibiotics.

The diagnosis and management of acute bacterial meningitis in resource-poor settings

Acute bacterial meningitis is more common in resource-poor than resource-rich settings. Survival is dependent on rapid diagnosis and early treatment, both of which are difficult to achieve when laboratory support and antibiotics are scarce. Diagnostic algorithms that use basic clinic and laboratory features to distinguish bacterial meningitis from other diseases can be useful. Analysis of the CSF is essential, and simple techniques can enhance the yield of diagnostic microbiology. Penicillin-resistant and chloramphenicol-resistant bacteria are a considerable threat in resource-poor settings that go undetected if CSF and blood can not be cultured. Generic formulations of ceftriaxone are becoming more affordable and available, and are effective against meningitis caused by penicillin-resistant or chloramphenicol-resistant bacteria. However, infection with Streptococcus pneumoniae with reduced susceptibility to ceftriaxone is reported increasingly, and alternatives are either too expensive (eg, vancomycin) or can not be widely recommended (eg, rifampicin, which is the key drug to treat tuberculosis) in resource-poor settings. Additionally, improved access to affordable antibiotics will not overcome the problems of poor access to hospitals and the fatal consequences of delayed treatment. The future rests with the provision of effective conjugate vaccines against S pneumoniae, Haemophilus influenzae, and Neisseria meningitides to children in the poorest regions of the world.