Laboratory diagnosis of bacterial meningitis

A rare case report of meningoencephalitis caused by Streptococcus porcinus

Acute pyogenic meningitis is a medical emergency. Bacteria are the major causative agents of pyogenic meningitis with Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis being the most common. Here, we describe a case of bacterial meningoencephalitis caused by Streptococcus porcinus. To our knowledge this is the first case described in literature. The patient was treated with ceftriaxone and supportive treatment.

Development and Validation of a Predictive Model for Postoperative Intracranial Infections in Neurosurgery with Risk Factor Analysis

BACKGROUND

Currently, the diagnosis of postneurosurgical intracranial infection is mainly dependent on cerebrospinal fluid (CSF) bacterial culture, which has the disadvantages of being time-consuming, having a low detection rate, and being easily affected by other factors. These disadvantages bring some difficulties to early diagnosis. Therefore, it is very important to construct a nomogram model to predict the risk of infection and provide a basis for early diagnosis and treatment.

METHODS

This retrospective study analyzed postneurosurgical patient data from the Fourth Affiliated Hospital of Harbin Medical University between January 2019 and September 2023. The patients were randomly assigned in an 8:2 ratio into the training cohort and the internal validation cohort. In the training cohort, initial screening of relevant indices was conducted via univariate analysis. Subsequently, the least absolute shrinkage and selection operator logistic regression identified significant potential risk factors for inclusion in the nomogram model. The model's discriminative ability was assessed using the area under the receiver operating characteristic curve, and its calibration was evaluated through calibration plots. The clinical utility of the model was determined using decision curve analysis and further validated by the internal validation cohort.

RESULTS

Multivariate logistic regression analysis of the training cohort identified 7 independent risk factors for postoperative intracranial infection: duration of postoperative external drainage (odds ratio [OR] 1.19, P = 0.005), continued fever (OR 2.11, P = 0.036), CSF turbidity (OR 2.73, P = 0.014), CSF pressure (OR 1.01, P = 0.018), CSF total protein level (OR 1.26, P = 0.026), CSF glucose concentration (OR 0.74, P = 0.029), and postoperative serum albumin level (OR 0.84, P < 0.001). Using these variables to construct the final model. The area under the receiver operating characteristic curve value of the model was 0.868 in the training cohort and 0.900 in the internal validation cohort. Calibration and the decision curve analysis indicated high accuracy and clinical benefit of the nomogram, findings that were corroborated in the validation cohort.

CONCLUSIONS

This study successfully developed a novel nomogram for predicting postoperative intracranial infection, demonstrating excellent predictive performance. It offers a pragmatic tool for the early diagnosis of intracranial infection.

Diagnostic and Monitoring Value of β-2 Transferrin and Transferrin for Intracranial Infection After Neurosurgery

BACKGROUND AND OBJECTIVES

After neurosurgery, intracranial infection is a common complication with high rates of clinical impairment and death. Traditional diagnostic approaches are time-consuming. Early and correct diagnosis improves infection control, treatment success, and survival. Novel markers are used to diagnose and classify post-neurosurgical meningitis (PNM) to overcome the difficulties of diagnosing postoperative intracranial infections and avoid the drawbacks of existing diagnostic measures. The objective was to investigate the diagnostic value of β-2 transferrin (β-2TF) and transferrin (TF) in the cerebrospinal fluid (CSF) for the identification of intracranial infection after neurosurgery.

METHODS

Owing to their symptoms and laboratory results, 168 patients with suspected intracranial infection after neurosurgery were divided into 3 groups: post-neurosurgical bacterial meningitis (PNBM; n = 61), post-neurosurgical aseptic meningitis (PNAM; n = 45), and non-PNM (n = 62). We measured lactate (LA), β-2TF, and TF levels in the CSF.

RESULTS

CSF LA levels were significantly higher in the PNM, PNBM, and PNAM groups compared with the non-PNM group ( P < .05). The CSF β-2TF level in PNM, PNBM, and PNAM were statistically higher than those in non-PNMs ( P < .05). CSF TF levels in the PNBM group were statistically higher than those in the PNAM and non-PNM groups ( P < .05). The PNBM and non-PNM receiver operating curve (ROC) analysis indicates that the cutoff values for the combination (LA, β-2TF, TF) was 0.349, and the area under the curve (AUC) was 0.945 ( P < .0001), with 92.86% sensitivity and 92.98% specificity. The PNAM and non-PNM ROC analysis indicates that the cutoff values for the combination (LA, β-2TF, TF) was 0.346, and the AUC was 0.962 ( P < .0001), with 89.29% sensitivity and 90.24% specificity. The PNM and non-PNM ROC analysis indicates that the cutoff values for the combination (LA, β-2TF, TF) was 0.609, and the AUC was 0.941 ( P < .0001), with 96.36% sensitivity and 82.83% specificity. A Glasgow Coma Scale score ≤8, LA, β-2TF/TF ratio, length of hospital stay, intensive care unit admission, poor surgical wound, and craniotomy were associated with poor outcomes ( P < .05). LA and β-2TF were independent risk factors for intracranial infection.

CONCLUSION

Postoperative cerebral infections can be identified using CSF β-2TF as a particular marker protein. CSF TF helps distinguish PNBM from PNAM. Combining CSF LA with them improves diagnostic speed, sensitivity, and accuracy. LA and β-2TF were independent risk factors for cerebral infection.

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.

Applying the pathogen-targeted next-generation sequencing method to pathogen identification in cerebrospinal fluid

Background

The cerebrospinal fluid (CSF) culture is a widely used method for the diagnosis of meningitis, but its detection sensitivity is low. Several new methods have been developed for pathogen detection, including metagenomic next-generation sequencing (mNGS) and pathogen-targeted NGS (ptNGS). In this study, we aimed to evaluate the performance of ptNGS in pathogen detection in CSF.

Methods

CSF specimens were acquired from 38 patients with meningitis who were diagnosed at Xuanwu Hospital, Capital Medical University between October 2020 and February 2021. DNA was extracted from the CSF samples, and pathogens were identified using both ptNGS and mNGS. SPSS 22.0 software was used to compare the pathogen detection performance of ptNGS and mNGS in CSF.

Results

Among the 38 patients with meningitis, 14 had a non-infectious disease (NID) and 24 had an infectious disease (ID). Of the 38 samples, both ptNGS and mNGS detected 9 (23.7%) positive samples, and 12 (31.6%) negative samples. Thirteen (34.2%) samples were detected to be positive by ptNGS only, and 4 (10.5%) were detected to be positive by mNGS only. The positivity rate detected by ptNGS for the ID group was higher than that detected by mNGS (P=0.080), and the positivity rates detected by ptNGS and mNGS for the NID group were comparable. The positive predictive value (PPV) and negative predictive value (NPV) of diagnosing an ID by ptNGS were 77.3% and 56.3%, respectively. While, the PPV and NPV of diagnosing an ID by mNGS were 76.9% and 44.0%, respectively. ptNGS increased the sensitivity rate by approximately 70%. The sensitivity rate of ptNGS was higher than that of mNGS (70.8% vs. 41.7%), while the specificity rate of mNGS was higher than that of ptNGS (78.6% vs. 64.3%). Additionally, ptNGS required a shorter time for pathogen diagnosis (15 vs. 24 hrs) and had lower costs than mNGS.

Conclusions

ptNGS has a number of advantages over mNGS, including its sensitivity, timeliness, and economy, all factors that are important considerations in clinical use.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members.As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Streptococcus oralis Meningitis with Gingival Bleeding in a Patient: A Case Report and Review of the Literature

An 81-year-old man with a history of gingival bleeding presented with a fever, headache, and drowsiness. His mouth and full dentures were unsanitary. Laboratory tests revealed Streptococcus oralis meningitis caused by odontogenic bacteremia. We reviewed eight reported cases, including the present case, because S. oralis meningitis is rare. Our review indicated that S. oralis meningitis needs to be considered when encountering cases of a fever, disturbance of consciousness, and headache with episodes of possible odontogenic bacteremia.

Detection of Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae in Culture Negative Cerebrospinal Fluid Samples from Meningitis Patients Using a Multiplex Polymerase Chain Reaction in Nepal

The rapid identification of bacteria causing meningitis is crucial as delays in the treatment increase mortality rate. Though considered as the gold standard for the laboratory diagnosis of bacterial meningitis, culture might give false negative results in a case of patients under antibiotics prior to lumbar puncture. This study aimed to detect Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae by a multiplex polymerase chain reaction (PCR) in culture-negative cerebrospinal fluid samples collected from clinically suspected meningitis cases attending different hospitals in Kathmandu, Nepal from January 2017 to December 2019. S. pneumoniae, N. meningitidis and H. influenzae were detected in 8.59% (33/384) of the specimens by PCR and 7.55% (29/384) of the specimens by culture. Correlation between culture and PCR of the same sample was good (Spearman's rho correlation coefficient = 0.932). However, the difference in positivity between culture and PCR was statistically not significant (p value > 0.05). In four specimens, culture could not detect any of the targeted bacteria whereas PCR could detect presence of H. influenzae. PCR increases the diagnostic yield for bacterial meningitis. PCR may be considered as an adjunctive test for establishing the cause of infection in culture negative clinically suspected meningitis cases.

A potential new recombinant echovirus 18 strain detected in a 4-year-old child with encephalitis in China in 2019

The species Enterovirus B includes diverse serotypes that can cause a wide spectrum of human diseases, such as aseptic encephalitis, myocarditis, and paralysis. In this study, a 4-year-old child was diagnosed with viral encephalitis, but the causative agent could not be identified using routine immunological tests. Using metagenomic RNA sequencing, a novel strain of enterovirus B, strain PC06, was identified, and its genome sequence was determined by RT-PCR and Sanger sequencing. The viral genome sequence was most similar to that of echovirus E18 strain E18-HeB15-54498/HeB/CHN/2015 (GenBank accession MG720261), with 87.73% nucleotide sequence identity, while the viral proteins shared 96.98% amino acid sequence identity with those of E18 strain Jena/AN1365/10 (GenBank accession no. KX139452). Phylogenetic analysis based on the VP1 and 3D genes revealed discrepant placement of PC06 in the two trees. In the 3D tree, PC06 formed a separate branch together with other recombinant E18 strains. Further recombination tests revealed that PC06 had possibly undergone recombination at a site between the structural and non-structural regions during its evolutionary history. Based on the analysis of VP1 phylogeny and using online genotyping tools, this potential recombinant is tentatively considered a strain of echovirus 18. This information might contribute to the diagnosis and prevention of related diseases.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members. As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Point-of-care cerebrospinal fluid Gram stain for the management of acute meningitis in adults: a retrospective observational study

Background

Gram stain of cerebrospinal fluid (CSF) is widely used in the diagnosis of acute meningitis, however, it is often conducted in the laboratory, as only some hospitals have access to point-of-care Gram stain (PCGS). The purpose of this study was to demonstrate the clinical impact and utility of PCGS in diagnosing and treating both bacterial and aseptic meningitis in adults.

Methods

This was a hospital-based, retrospective observational study at a referral center in Okinawa, Japan. We reviewed the records of all patients aged 15 years or older who were admitted to the Division of Infectious Diseases between 1995 and 2015 and finally diagnosed with bacterial (n = 34) or aseptic meningitis (n = 97). For bacterial meningitis, we compared the treatments that were actually selected based on PCGS with simulated treatments that would have been based on the Japanese guidelines. For aseptic meningitis, we compared the rates of antibiotic use between real cases where PCGS was available and real cases where it was not.

Results

PCGS was the most precise predictor for differentiating between bacterial and aseptic meningitis (sensitivity 91.2%, specificity 98.9%), being superior in this regard to medical histories, vital signs and physical examinations, and laboratory data available in the emergency room (ER). In bacterial meningitis, PCGS reduced the frequency of meropenem use (1/34 = 3.0%) compared with simulated cases in which PCGS was not available (19/34 = 55.9%) (p< 0.001). In aseptic meningitis cases, the rate of antibiotic administration was lower when PCGS was used (38/97 = 39.2%) than when it was not (45/74 = 60.8%) (p = 0.006).

Conclusions

PCGS of CSF distinguishes between bacterial and aseptic meningitis more accurately than other predictors available in the ER. Patients with bacterial meningitis are more likely to receive narrower-spectrum antimicrobials when PCGS is used than when it is not. PCGS of CSF thus can potentially suppress the empiric use of antimicrobials for aseptic meningitis.

Effect of delayed entry on performance of the BACT/ALERT FAN PLUS bottles in the BACT/ALERT VIRTUO blood culture system

Delayed entry of patient blood culture samples into a microbial detection system is unavoidable at times, due to off-shift staffing or transporting samples to centralized laboratories. Pre-incubation time and temperature of blood culture bottles are the most critical factors impacting recovery and detection of microorganisms. A total of 1377 BACT/ALERT® (BTA) Fastidious Antimicrobial Neutralization (FAN® PLUS) bottles (FA PLUS, FN PLUS, and PF PLUS) were tested after delayed entry times of 24 and 36 h at 20–25 °C (room temperature, RT) prior to loading into the BACT/ALERT® VIRTUO® microbial detection system (VIRTUO). Clinically relevant organisms were inoculated into bottles with 5–84 colony forming units (CFU) per bottle, and human blood (0 to 10 mL), and then loaded into the VIRTUO. When bottles were loaded without delay, a mean time to detection (TTD) of 9.6 h was observed. For delayed bottles, the TTD reported by the VIRTUO was added to the 24-h and 36-h delay times and resulted in average time to results of 32.5 h and 42.5 h, respectively. The FAN PLUS bottles in conjunction with the VIRTUO produced acceptable results when delays up to 24 h at 20–25 °C occur in loading.

Cerebrospinal Fluid Findings Are Poor Predictors of Appropriate FilmArray Meningitis/Encephalitis Panel Utilization in Pediatric Patients

Molecular testing of cerebrospinal fluid (CSF) using the BioFire FilmArray meningitis/encephalitis (FA-M/E) panel permits rapid, simultaneous pathogen detection. Due to the broad spectrum of targeted organisms, FA-M/E testing may be restricted to patients with abnormal CSF findings. We sought to determine if restriction is appropriate in our previously healthy and/or immunocompromised pediatric patients. FA-M/E was ordered on 1,025 CSF samples from 948 patients; 121 (11.8%) specimens were FA-M/E positive. Of these, 89 (73.6%) were virus positive, and 30 (24.8%) were bacterium positive. The most common targets detected were enterovirus (n = 38), human herpesvirus 6 (HHV-6) (n = 30), and Streptococcus pneumoniae (n = 14). Pleocytosis with white blood cell (WBC) levels of ≥5 cells/mm³ and ≥10 cells/mm³ were found in 33.1% and 24.3% of all specimens, respectively. Using WBC levels of ≥5 cells/mm³, 63.4% (59/93) of positive specimens exhibited pleocytosis, compared to 29.5% (233/789) of negative specimens. Among positive specimens, 54.4% (37/68) of viral and 87% (20/23) of bacterial cases had pleocytosis. The use of a pleocytosis cutoff of ≥10 cells/mm³ would have missed an additional enterovirus, one cytomegalovirus (CMV), and two HHV-6 diagnoses. CSF glucose and protein levels were normal for 83/116 (75.2%) and 51/116 (44%) positive specimens. Abnormal glucose in combination with WBC levels of ≥10 cells/mm³ showed high specificity (94.5%) and was a better predictor of FA-M/E positivity than abnormal protein. Sensitivity and positive predictive values were <90% for all biomarkers. CSF pleocytosis and abnormal glucose/protein were poor predictors of FA-M/E. Restricting FA-M/E orders based on pleocytosis or other abnormal parameters would have resulted in missed diagnostic opportunities, particularly for the detection of viruses in both previously healthy and immunocompromised patients.

Higher Procalcitonin Level in Cerebrospinal Fluid than in Serum Is a Feasible Indicator for Diagnosis of Intracranial Infection

Objective: To explore the value of the difference in procalcitonin (PCT) levels in serum and cerebrospinal fluid (CSF) for diagnosing intracranial infection in post-neurosurgical patients. Methods: Patients who were treated at our hospital after craniotomy from January 2015 to January 2019 were enrolled in this study. Twenty patients eventually diagnosed with intracranial infection were included in a study group and 22 patients with no intracranial infection were included in a control group. A t-test was used to compare the differences between serum and CSF PCT levels of PCT, and the diagnostic value of PCT was evaluated by receiver operating characteristic (ROC) curve analysis. Results: The serum PCT levels in the study and control groups were 0. 10 ± 0. 03 ng/mL and 0. 09 ± 0. 03 ng/mL, respectively, and they were not substantially different between the groups. The CSF PCT level in the study group was substantially higher than that in the control group, with values of 0. 13 ± 0. 03 ng/mL and 0. 07 ± 0. 02 ng/mL, respectively. The CSF/serum PCT ratio in the study group was substantially higher than that in the control group, with values of 1. 31 ± 0. 19 and 0. 79 ± 0. 23, respectively. The areas under the ROC curve for serum PCT, CSF PCT and the CSF/serum PCT ratio were 0. 56, 0. 92, and 0. 95, respectively, resulting in a substantial difference among the three groups. Conclusion: CSF PCT may be a valuable marker for diagnosing intracranial infection in patients after neurosurgery; in particular, the specificity of CSF PCT is higher if the CSF PCT level is higher than the serum PCT level.

Comparison of acridine orange fluorescent microscopy and gram stain light microscopy for the rapid detection of bacteria in cerebrospinal fluid

OBJECTIVE

Bacterial meningitis is a life threatening condition that requires prompt recognition and treatment. Currently, Gram stain is widely used for the microscopic detection of bacterial pathogens in cerebrospinal fluid (CSF). In Nepal, fluorescent microscopes have been installed in laboratories as a part of the National tuberculosis control program. However, information on the utility of the acridine orange (AO) stain for the direct detection of bacteria in CSF samples in Nepal is not available. Therefore, this study aims to compare Gram stain and AO stain for the rapid detection of bacterial pathogens in CSF of clinically suspected meningitis cases in Kathmandu, Nepal.

RESULTS

Bacterial pathogens were detected in 9.30% (36/387) by either of the three tests, 9.04% (35/387) by AO stain, 8.27% (32/387) by culture and 6.46% (25/387) by Gram's stain. Considering culture as a gold standard, the sensitivity of AO stain was higher than Gram stain. The specificity of AO stain was 98.87%. Detection and differentiation of the bacteria was much clear in AO staining than Gram staining. AO is a better alternative to Gram stain in the rapid detection of bacterial pathogens in CSF in the setting where fluorescent microscope is available.

Meningococcal Meningitis: A Multicentric Hospital-based Study in Kathmandu, Nepal

Background:

The global epidemiology of meningococcal disease varies markedly by region and over time. In Nepal, information on serogroup of meningococci is not available since the 1983 serogroup A epidemic in Kathmandu.

Objective:

To provide some fundamental data on the circulating serogroups of meningococci for potential meningococcal immunization programs in Nepal.

Methods:

This cross-sectional prospective study was conducted from January 2017 to December 2018 among 387 clinically suspected meningitis cases. Cerebrospinal fluid samples were collected by lumbar puncture technique at five referral hospitals of Kathmandu and processed by conventional cultural techniques. Neisseria meningitidis was identified by colony morphology, Gram staining and oxidase test. Serogrouping of meningococci was performed by slide agglutination test. Antibiotic susceptibility testing was done by the modified Kirby Bauer disc diffusion method. The data was entered into IBM SPSS Statistics 21 software and a p-value of <0.05 was considered significant.

Results:

Thirty-two samples were positive by culture for a bacterial pathogen with 2.3% of meningococci. All except one meningococcal meningitis cases were aged below 15 years. All N.meningitidis isolates belonged to serogroup A and were susceptible to ceftriaxone, chloramphenicol, meropenem and minocycline; however, 22% isolates showed resistance to cotrimoxazole and 11% intermediate resistance to ciprofloxacin.

Conclusion:

The circulating serogroup of N. meningitidis in Kathmandu has not changed over the past 35 years. The prevalence of meningococcal meningitis in Kathmandu is low but might be underestimated due to the sole use of culture-based diagnostic methods. Detection of meningococci by alternative methods may be useful in the precise estimation of actual disease burden.

Acute Bacterial Meningitis

PURPOSE OF REVIEW

While acute bacterial meningitis is becoming less common in developed countries because of the widespread use of vaccines against Streptococcus pneumoniae, Neisseria meningitides, and Haemophilus influenzae, bacterial meningitis still occurs worldwide, with peak incidence in young children and the elderly. Bacterial meningitis is usually lethal unless appropriate antibiotics that cross the blood-brain barrier are given. Clinical suspicion of bacterial meningitis begins when patients present with the abrupt onset of fever, headache, and meningismus.

RECENT FINDINGS

New technologies are being developed for more rapid identification of the bacterial species causing meningitis. When appropriate, administration of adjunctive dexamethasone with the antibiotics often lessens neurologic sequelae in survivors, which may include aphasia, ataxia, paresis, hearing loss, and cognitive impairment.

SUMMARY

Confirmation of the diagnosis of bacterial meningitis comes mainly from examination and culture of CSF obtained from a lumbar puncture. Typically, the CSF shows an elevated neutrophil count, elevated protein, depressed glucose, positive Gram stain, and growth of the bacteria on appropriate culture media. Antibiotic sensitivities of the bacteria determine the appropriate antibiotics, although an educated guess of the best antibiotics to be given promptly must be made until the antibiotic sensitivities return, usually in a few days.

Bacterial meningitis in Sudanese children; critical evaluation of the clinical decision using clinical prediction rules

BACKGROUND

Sudan falls in the meningitis belt where most global cases of bacterial meningitis are reported. Highly accurate decision support tools have been developed by international specialized societies to guide the diagnosis and limit unnecessary hospital admissions and prolonged antibiotic use that have been frequently reported from countries around the world. The goals of this study are to critically evaluate the clinical decision of bacterial meningitis in children in Sudan using clinical prediction rules and to identify the current bacterial aetiology.

METHODS

This cross-sectional hospital-based study was conducted in October to July of 2010 in a major referral pediatric hospital in Khartoum, Sudan. Febrile children age 1 day to 15 years who were provisionally diagnosed as having meningitis on admission were included (n = 503). Cerebrospinal fluid (CSF) specimens were obtained from all patients while clinical and demographic data were available for only 404. Conventional laboratory investigations were performed. The clinical decision was evaluated by the International Classification of Diseases-Clinical Modification code 320.9 and the Bacterial Meningitis Score. Ethical clearance and permissions were obtained.

RESULTS

Out of 503 provisionally diagnosed bacterial meningitis patients, the final clinical confirmation was assigned to 55.9%. When codes were applied; 5.7% (23/404) with CSF pleocytosis were re-classified as High Risk for bacterial meningitis and 1.5% (6/404) with confirmed bacterial aetiology as Proven Bacterial Meningitis. Neisseria meningitidis was identified in 0.7% (3/404) and Streptococcus pneumoniae in another 0.7%. Typical laboratory findings (i.e. CSF pleocytosis and/or low glucose and high protein concentrations, Gram positive or Gram negative diplococcic, positive bacterial culture) were seen in 5 (83%). Clinically, patients showed fever, seizures, chills, headache, vomiting, stiff neck and bulging fontanelle. All confirmed cases were less than 5 years old and were admitted in summer. All patients were prescribed with antibiotics; they were all recovered and discharged.

CONCLUSIONS

Bacterial meningitis is over-diagnosed in hospitals in Khartoum therefore clinical prediction rules must be adopted and applied to guide the clinical decision. The sole bacterial aetiology in this selected group of Sudanese children remain N. meningitidis and S. pneumoniae, but with significant decrease in prevalence. Some cases showed atypical clinical and laboratory findings.

Rapid diagnosis of bacterial meningitis by nanopore 16S amplicon sequencing: A pilot study

Early administration of antibiotics is crucial in the management of bacterial meningitis. Rapid pathogen identification helps to make a definite diagnosis of bacterial meningitis and enables tailored antibiotic treatment. We investigated if the 16S amplicon sequencing performed by MinION, a nanopore sequencer, was capable of rapid pathogen identification in bacterial meningitis. Six retrospective cases of confirmed bacterial meningitis and two prospective cases were included. The initial cerebrospinal fluid (CSF) samples of these patients were used for the experiments. DNA was extracted from the CSF, and PCR was performed on the 16S ribosomal DNA (16S rDNA). Sequencing libraries were prepared using the PCR products, and MinION sequencing was performed for up to 3 h. The reads were aligned to the bacterial database, and the results were compared to the conventional culture studies. Pathogenic bacteria were successfully detected from the CSF by 16S sequencing in all retrospective cases. 16S amplicon sequencing was more sensitive than conventional diagnostic tests and worked properly even in antibiotics-treated samples. MinION sequencing significantly reduced the turnaround time, and even 10 min of sequencing was sufficient for pathogen detection in certain cases. Protocol adjustment could further increase the sensitivity and reduce the turnaround time for MinION sequencing. Finally, the prospective application of MinION 16S sequencing was successful. Nanopore 16S amplicon sequencing is capable of rapid bacterial identification from the CSF of the bacterial meningitis patients. It may have many advantages over conventional diagnostic tests and should therefore be applied in a larger number of patients in the future.

Diagnostic Testing in Central Nervous System Infection

Patients with central nervous system (CNS) infection experience very high levels of morbidity and mortality, in part because of the many challenges inherent to the diagnosis of CNS infection and identification of a causative pathogen. The clinical presentation of CNS infection is nonspecific, so clinicians must often order and interpret many diagnostic tests in parallel. This can be a daunting task given the large number of potential pathogens and the availability of different testing modalities. Here, we review traditional diagnostic techniques including Gram stain and culture, serology, and polymerase chain reaction (PCR). We highlight which of these are recommended for the pathogens most commonly tested among U.S. patients with suspected CNS infection. Finally, we describe the newer broad-range diagnostic approaches, multiplex PCR and metagenomic sequencing, which are increasingly used in clinical practice.

Usefulness of the FilmArray meningitis/encephalitis (M/E) panel for the diagnosis of infectious meningitis and encephalitis in Taiwan

BACKGROUND/PURPOSE

Early recognition of causative pathogens is critical for the appropriate management of central nervous system infection and improved outcomes. The BioFire^® FilmArray^® Meningitis/Encephalitis Panel (BioFire^® ME Panel, BioFire Diagnostics) is the first U.S. Food and Drug Administration (FDA)-approved multiplex PCR assay that allows the rapid detection of 14 pathogens, including bacteria (n = 6), viruses (n = 7), and fungi (n = 1), from cerebrospinal fluid (CSF). The performance of the panel is expected to be dependent on the epidemiology of M/E in different geographical regions.

METHODS

In this preliminary study, we used the BioFire^® ME Panel in 42 subjects who presented to the emergency department with symptoms of M/E in our hospital. The results were compared to conventional culture, antigen detection, PCR, and various laboratory findings.

RESULTS

The panel detected six positive samples, of which five were viral and one bacterial. We observed an overall agreement rate of 88% between the BioFire^® ME Panel results and the conventional methods. There were no false-positive findings, but five discordant results were observed for enterovirus, herpes simplex virus type 1, Escherichia coli, and Cryptococcus species.

CONCLUSIONS

The BioFire^® ME Panel performed equivalently to the traditional PCR methods for virus detection, and better than bacterial cultures. This revolutionary system represents a paradigm shift in the diagnosis of M/E and may aid in the rapid identification of community-acquired M/E. However, the usefulness of this tool is limited in regions with a high prevalence of infectious M/E caused by microorganisms not included in the panel.

Meningitis in adults: diagnosis and management

Bacterial meningitis is a medical emergency. All clinicians who provide acute medical care require a sound understanding of the priorities of managing a patient with suspected meningitis during the first hour. These include obtaining blood cultures, performing lumbar puncture and initiating appropriate therapy, while avoiding harmful delays such as those that result from not administering treatment until neuroimaging has been performed. Despite the increasing availability of newer diagnostic techniques, the interpretation of cerebrospinal fluid parameters remains a vital skill for clinicians. International and local guidelines differ with regard to initial empirical therapy of bacterial meningitis in adults; the North American guideline recommends ceftriaxone and vancomycin for all patients, while the Australian, UK and European guidelines recommend that vancomycin only be added for patients who are more likely to have pneumococcal meningitis or who have a higher likelihood of being infected with a strain of Streptococcus pneumoniae with reduced susceptibility to ceftriaxone. Patients with risk factors for Listeria meningitis also require an anti-Listeria agent, such as benzylpenicillin, to be added to this treatment regimen. Dexamethasone should be a routine component of empirical therapy due to its proven role in reducing morbidity and mortality from pneumococcal meningitis.

Cerebrospinal Fluid Lactate as an Indicator for Post-neurosurgical Bacterial Meningitis

Objective

To evaluate the interest of cerebrospinal fluid (CSF) lactate assay for the diagnosis of post-neurosurgical bacterial meningitis (PBM).

Methods

We conducted at our neurosurgical resuscitation unit a prospective study of patients who underwent elective or emergency craniotomy. Lumbar puncture was performed in all patients who had clinical suspicion of PBM for CSF culture and cytological and chemical analysis (glucose, protein, lactate). The diagnosis of PBM is made according to the criteria proposed by the Center for Disease Control and Prevention (CDC). Receiver Operating Characteristic (ROC) was used to determine the diagnostic accuracy of CSF lactate.

Results

72 patients were studied and only 32 of them had the clinical and biological criteria of the diagnosis of PBM. Median CSF lactate was 6.18 mmol/L for PBM vs 2.63 mmol/L for no PBM (p < 0.001). CSF lactate may predict the presence PBM, with a AUC of 0.98 and NPV of 99.1. The analysis of Youden's index also confirms the good diagnostic power of CSF lactate with a value of 83 at a cut-off value of 4 mmol/L and a sensitivity of 92.3% and specificity of 91.6%.

Conclusion

Our study shows that the CSF lactate as an indicator for PBM. It is a fast and simple test that can help the clinician to optimize the management of PBM and decrease premature cessation of antibiotics.

How to cite this article

Lotfi R, Ines B, et al. Cerebrospinal Fluid Lactate as an Indicator for Post-neurosurgical Bacterial Meningitis. Indian J Crit Care Med 2019;23(3):127-130.

Blood Culture Results Reporting: How Fast Is Your Laboratory and Is Faster Better?

Blood cultures are one of the most common and most important tests performed in clinical microbiology laboratories. Variables and technology that improve and speed the recovery of blood stream pathogens have been published in the Journal of Clinical Microbiology since its inception in 1975. Despite the importance of blood cultures, little research has focused on the turnaround time of blood culture reports. In this issue of the Journal of Clinical Microbiology, Y. P. Tabak et al. (J Clin Microbiol 56:e00500-18, 2018, https://doi.org/10.1128/JCM.00500-18) report the results of an investigation of Gram stain, organism identification, and susceptibility report turnaround times for 165,593 blood cultures from 13 laboratories. These data provide a starting point for clinical laboratories to establish targets for blood culture result reporting.

Rapid pathogen identification using a novel microarray-based assay with purulent meningitis in cerebrospinal fluid

In order to improve the diagnosis of pathogenic bacteria in cerebrospinal fluid (CSF) with purulent meningitis, we developed a DNA microarray technique for simultaneous detection and identification of seven target bacterium. DNA were extracted from 24 CSF samples with purulent meningitis (or suspected purulent meningitis). The specific genes of each pathogen were chosen as the amplification target, performed the polymerase chain reaction (PCR), labeled with a fluorescence dye, and hybridized to the oligonucleotide probes on the microarray. There is no significant cross-hybridization fluorescent signal occurred in untargeted bacteria. There were 87.5% (21/24) positive results in DNA microarray compared with the 58.3% (14/24) of the CSF culture test. Of which 58.3% (14/24) of the patients with culture-confirmed purulent meningitis, 37.5% (9/24) patients who were not confirmed by culture test but were demonstrated by the clinical diagnosis and DNA microarray. Multiple bacterial infections were detected in 5 cases by the microarray. In addition, the number of gene copies was carried out to determine the sensitivity of this technique, which was shown to be 3.5 × 10¹ copies/μL. The results revealed that the microarray technique which target pathogens of the CSF specimen is better specificity, accuracy, and sensitivity than traditional culture method. The microarray method is an effective tool for rapidly detecting more target pathogens and identifying the subtypes of strains which can eliminate the impact of the different individuals with purulent meningitis for prompt diagnosis and treatment.

The combination of cerebrospinal fluid procalcitonin, lactate, interleukin-8 and interleukin-10 concentrations for the diagnosis of postneurosurgical bacterial meningitis: A prospective study

Background

The differential diagnosis between postneurosurgical bacterial meningitis and aseptic meningitis remains challenging both for the clinician and the laboratory. Combinations of markers, as opposed to single ones, may improve diagnosis and thereby survival.

Methods

This prospective cohort study included patients with suspected bacterial meningitis after neurosurgery. The patients were divided into two groups according to the diagnostic criteria of meningitis involving a postneurosurgical bacterial meningitis group and a postneurosurgical aseptic meningitis group. Four biomarkers, including cerebrospinal fluid procalcitonin, lactate, interleukin-8 and interleukin-10 were assayed separately, and three algorithms were constructed using a linear combination. The area under the receiver operating characteristic curve was used to compare their performances.

Results

A cohort of 112 patients was enrolled in our study. Forty-three patients were diagnosed with postneurosurgical bacterial meningitis, and the cerebrospinal fluid values of their biomarkers were higher in patients with postneurosurgical bacterial meningitis than with postneurosurgical aseptic meningitis. The area under the receiver operating characteristic curves for the detection of postneurosurgical bacterial meningitis were 0.803 (95% confidence interval [CI], 0.724–0.883) for procalcitonin; 0.936 (95% CI, 0.895–0.977) for lactate; 0.771 (95% CI, 0.683–0.860) for interleukin-8; 0.860 (95% CI, 0.797–0.929) for interleukin-10; 0.937 (95% CI, 0.897–0.977) for the composite two-marker test; 0.945 (95% CI, 0.908–0.982) for the composite three-marker test and 0.954 (95% CI, 0.922–0.989) for the composite of all tests. The area under the receiver operating characteristic curves of the combination tests were greater than those of the single markers.

Conclusions

Combining information from several markers improved the diagnostic accuracy in detecting postneurosurgical bacterial meningitis.

MALDI-TOF mass spectrometry technology for detecting biomarkers of antimicrobial resistance: current achievements and future perspectives

The laboratory diagnosis of infections is based on pathogen identification and antimicrobial susceptibility determination. The gold standard of cultivation, isolation and susceptibility testing is a time-consuming procedure and in some cases this can be threatening for patients' outcome. In the current review the applications of mass spectrometry in pathogen identification and especially in detecting biomarkers of antimicrobial resistance are analyzed. MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry is a new technology that has revolutionized pathogen identification and has also proven to accelerate detection of antimicrobial resistance compared to the traditional antibiotic susceptibility tests (AST) as well as DNA amplification methodologies. The technology has incorporated up to know four different methodologies: (I) the detection of differences of mass spectra of susceptible and resistant isolates of a given microorganism using the classical strain typing methodology; (II) the analysis of bacterial induced hydrolysis of β-lactam antibiotics; (III) the detection of stable (non-radioactive) isotope-labeled amino acids; and (IV) the analysis of bacterial growth in the presence and absence of antibiotics using an internal standard. The implementation of MALDI-TOF methodologies has improved detection of resistance in aerobic, Gram-positive and Gram-negative bacteria, mycobacteria, anaerobic bacteria, fungi and viruses. The MALDI-TOF is an easy to use, rapid, reliable, economical, and environmentally friendly methodology. However, this technology needs further development of research protocols that will be validated for routine application.

Cerebrospinal fluid monocytes in bacterial meningitis, viral meningitis, and neuroborreliosis

OBJECTIVE

Cerebrospinal fluid (CSF) leukocytes analysis is commonly used to diagnose meningitis and to differentiate bacterial from viral meningitis. Interpreting CSF monocytes can be difficult for physicians, especially in France where lymphocytes and monocytes results are sometimes pooled.

PATIENTS AND METHODS

We assessed SF monocytes in patients presenting with microbiologically confirmed meningitis (CSF leukocyte count>10/mm³ for adults or >30/mm³ for children<2 months), i.e. bacterial meningitis (BM), viral meningitis (VM), and neuroborreliosis (NB).

RESULTS

Two-hundred patients (82 BM, 86 VM, and 32 NB) were included. The proportions of monocytes were higher in VM (median 8%; range 0-57%) than in BM (median 5%; range 0-60%, P=0.03) or NB (median 5%; range 0-53%, P=0.46), with a high value overlap between conditions.

CONCLUSION

CSF monocytes should not be used to discriminate BM from VM and NB because of value overlaps.

Meningococcal disease, a clinical and epidemiological review

Meningococcal disease is the acute infection caused by Neisseria meningitidis, which has humans as the only natural host. The disease is widespread around the globe and is known for its epidemical potential and high rates of lethality and morbidity. The highest number of cases of the disease is registered in the semi-arid regions of sub-Saharan Africa. In Brazil, it is endemic with occasional outbreaks, epidemics and sporadic cases occurring throughout the year, especially in the winter. The major epidemics of the disease occurred in Brazil in the 70's caused by serogroups A and C. Serogroups B, C and Y represent the majority of cases in Europe, the Americas and Australia. However, there has been a growing increase in serogroup W in some areas. The pathogen transmission happens for respiratory route (droplets) and clinically can lead to meningitis and sepsis (meningococcemia). The treatment is made with antimicrobial and supportive care. For successful prevention, we have some measures like vaccination, chemoprophylaxis and droplets' precautions. In this review, we have described and clarify clinical features of the disease caused by N. meningitidis regarding its relevance for healthcare professionals.

Listeria monocytogenes Meningitis Complicating Rotavirus Gastroenteritis in an Immunocompetent Child

Listeria monocytogenes only occasionally causes bacterial meningitis in immunocompetent children. We report a case of L. monocytogenes meningitis associated with rotavirus gastroenteritis. The patient was a previously healthy 20-month-old girl who was admitted because of sustained fever and lethargy after suffering from gastroenteritis for 6 days. The patient's peripheral white blood cell count was 18,600/µL and the C-reactive protein level was 2.44 mg/dL. A stool sample tested positive for rotavirus antigen. A cerebrospinal fluid (CSF) sample showed pleocytosis. Cultures of the CSF and stool samples revealed the presence of L. monocytogenes. The patient was successfully treated with ampicillin and gentamicin. We speculate that translocation of enteric flora across the intestinal epithelium that had been damaged by rotavirus gastroenteritis might have caused bacteremia that disseminated into the CSF. Both listeriosis and secondary systemic infection after rotavirus gastroenteritis are rare but not unknown. Initiation of appropriate treatment as soon as possible is important for all types of bacterial meningitis. This rare but serious complication should be taken into consideration even if the patient does not have any medical history of immune-related problems.

Broadband Infrared Spectroscopy for Non-Contact Measurement of Neurological Disease Biomarkers in Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is a clear and colorless biological fluid which circulates within brain ventricles (cavities), the spinal cord's central canal, the space between the brain and the spinal cord, as well as their protective coverings, the meninges. Cerebrospinal fluid contains different constituents, such as albumin and lactate, whose levels are used clinically as biomarkers of neurodegenerative disorders. In current clinical practice, analysis of CSF content for the diagnosis of central nervous system disorders requires an invasive procedure known as lumbar puncture or spinal tap. With the aim of developing a noninvasive alternative, we report here the spectral behavior of albumin and lactate over a broad wavelength range of 600-2000 nm, after each was added separately at varying normal and abnormal concentration levels to artificial CSF ( aCSF). Spectral measurements were conducted simultaneously by two different spectrometers working at different spectral ranges in transmittance mode. Spectral analysis revealed that albumin and lactate each possesses its own first and second derivative absorbance spectra fingerprint between 1660 and 1810 nm. Distinguishing albumin from lactate by their spectral data enabled the differentiation between aCSF conditions modeling different neurological disorders. Spectral changes of each compound strongly correlated ( R²> 0.9) with absorbance derivative spectra peaks at specific wavelengths, when analyzed by linear regression with variations in their concentration. These findings suggest the feasibility of CSF biomarker assessment by broadband infrared spectroscopy.

Management of infections associated with neurocritical care

The reported incidence of hospital-acquired infections (HAIs) in the neurointensive care unit (NICU) ranges from 20% to 30%. HAIs in US hospitals cost between $28 and $45 billion per year in direct medical costs. These infections are associated with increased length of hospital stay and increased morbidity and mortality. Infection risk is increased in NICU patients due to medication side-effects, catheter and line placement, neurosurgical procedures, and acquired immune suppression secondary to steroid/barbiturate use and brain injury itself. Some of these infections may be preventable but many are not. Their appearance do not always constitute a failure of prevention or physician error. Neurointensivists require indepth knowledge of common nosocomial infections, their diagnosis and treatment, and an approach to evidence-based practices that improve processes of care and reduce HAIs.

Challenges of bacterial meningitis case management in low income settings: an experience from Ethiopia

OBJECTIVE

To investigate the current diagnostic and therapeutic strategies used in the care of patients with suspected bacterial meningitis at teaching hospitals in Ethiopia.

METHODS

This was a hospital-based retrospective study conducted at four teaching hospitals in different regions of Ethiopia. Participants were patients aged 14 years and older treated for suspected bacterial meningitis. Presenting complaints, diagnostic strategies used and treatments given were obtained from clinical records.

RESULT

A total of 425 patients were included in the study; 52.7% were men and 83.8% were younger than 50 years. Fever, headache, neck stiffness and impaired consciousness were the most common clinical presentations; 55.5% underwent lumbar puncture. Overall, only 96 (22.6%) patients had cerebrospinal fluid abnormalities compatible with bacterial meningitis. A causative bacterium was identified in only 14 cases. Ceftriaxone was used as the empiric treatment of choice, either alone or in combination with other antibiotics; 17.6% of patients were also given vancomycin. Adjunctive dexamethasone was given to 50.4%.

CONCLUSION

Most patients treated as bacterial meningitis did not receive a proper diagnostic workup. The choice of antibiotic was not tailored to the specific clinical condition of the patient. Such an approach may result in poor treatment outcomes and lead to antibiotic resistance. Management of patients with suspected bacterial meningitis should be supported by analysis of cerebrospinal fluid, and treatment should be tailored to local evidence and current evidence-based recommendations.

Neutrophil-to-lymphocyte ratio in the differential diagnosis of acute bacterial meningitis

The differential diagnosis of acute community-acquired meningitis is of paramount importance in both therapeutic and healthcare-related economic terms. Despite the routinely used markers, novel, easily calculated, and rapidly available biomarkers are needed particularly in resource-poor settings. A promising, exponentially studied inflammatory marker is the neutrophil-to-lymphocyte ratio (NLR), albeit not assessed in meningitis. The aim of this study was to investigate the utility of the NLR in the differential diagnosis of acute meningitis. Data on cerebrospinal fluid (CSF) and blood leukocyte parameters from more than 4,000 patients diagnosed with either bacterial or viral meningitis in Greece during the period 2006-2013 were retrospectively examined. The diagnostic accuracy of the NLR and neutrophil counts in CSF and blood were evaluated by receiver operating characteristic curves. The discrimination ability of both the NLR and neutrophil counts was significantly higher in CSF than in blood. The optimal cutoff values of the NLR and neutrophil counts were 2 in CSF vs 8 in blood, and 287 cells in CSF vs 12,100 cells in blood, respectively. For these values, sensitivity, negative predictive value, and odds ratio were statistically significantly higher in CSF than blood for both markers. Logistic regression analysis showed that the CSF NLR carries independent and additive information to neutrophil counts in the differential diagnosis of acute meningitis. This study is the first one to assess NLR in acute meningitis, providing promising results for its differential diagnosis.

A ZnO–CNT nanocomposite based electrochemical DNA biosensor for meningitis detection

The article focuses on the synthesis of ZnO and CNTs based electrochemical DNA biosensor and its application towards meningitis DNA detection with high sensitivity as well as selectivity.

Multiplex polymerase chain reaction assay developed to diagnose adult bacterial meningitis in Taiwan

Acute bacterial meningitis causes high morbidity and mortality; the associated clinical symptoms often are insensitive or non-specific; and the pathogenic bacteria are geographically diverse. Clinical diagnosis requires a rapid and accurate methodology. This study aimed to develop a new multiplex polymerase chain reaction (mPCR) assay to detect simultaneously six major bacteria that cause adult bacterial meningitis in Taiwan: Klebsiella pneumoniae, Pseudomonas aeruginosa, Streptococcus pneumoniae, Staphylococcus aureus, Escherichia coli, and Acinetobacter baumannii. Species-specific primers for the six bacteria were developed using reference strains. The specificities of the mPCRs for these bacteria were validated, and the sensitivities were evaluated via serial dilutions. The mPCR assay specifically detected all of the six pathogens, particularly with sensitivities of 12 colony forming units (CFU)/mL, 90 CFU/mL, and 390 CFU/mL for E. coli, S. pneumoniae, and K. pneumoniae, respectively. This mPCR assay is a rapid and specific tool to detect the six major bacterial pathogens that cause acute adult meningitis in Taiwan, particularly sensitive for detecting E. coli, S. pneumoniae, and K. pneumoniae. The assay may facilitate early diagnosis and guidance for antimicrobial therapy for adult patients with this deadly disease in Taiwan.

Bacterial meningitis in children under 15 years of age in Nepal

BACKGROUND

Bacterial meningitis in children is a life-threatening problem resulting in severe morbidity and mortality. For the prompt initiation of antibacterial therapy, rapid and reliable diagnostic methods are of utmost importance. Therefore, this study was designed to find out the rate of bacterial pathogens of meningitis from suspected cases by performing conventional methods and latex agglutination.

METHODS

A descriptive type of study was carried out from May 2012 to April 2013. Cerebrospinal fluid (CSF) specimens from 252 suspected cases of meningitis were subjected for Gram staining, bacterial culture and latex agglutination test. The identification of growth of bacteria was done following standard microbiological methods recommended by American Society for Microbiology. Antibiotic sensitivity testing was done by modified Kirby-Bauer disk diffusion method.

RESULTS

From the total 252 suspected cases, 7.2 % bacterial meningitis was revealed by Gram staining and culture methods whereas latex agglutination method detected 5.6 %. Gram-negative organisms contributed the majority of the cases (72.2 %) with Haemophilus influenzae as the leading pathogen for meningitis. Overall, 33.3 % mortality rate was found.

CONCLUSIONS

In conclusion, a significant rate of bacterial meningitis was found in this study prompting concern for national wide surveillance.

Comparative proteomics of cerebrospinal fluid reveals a predictive model for differential diagnosis of pneumococcal, meningococcal, and enteroviral meningitis, and novel putative therapeutic targets

BACKGROUND

Meningitis is the inflammation of the meninges in response to infection or chemical agents. While aseptic meningitis, most frequently caused by enteroviruses, is usually benign with a self-limiting course, bacterial meningitis remains associated with high morbidity and mortality rates, despite advances in antimicrobial therapy and intensive care. Fast and accurate differential diagnosis is crucial for assertive choice of the appropriate therapeutic approach for each form of meningitis.

METHODS

We used 2D-PAGE and mass spectrometry to identify the cerebrospinal fluid proteome specifically related to the host response to pneumococcal, meningococcal, and enteroviral meningitis. The disease-specific proteome signatures were inspected by pathway analysis.

RESULTS

Unique cerebrospinal fluid proteome signatures were found to the three aetiological forms of meningitis investigated, and a qualitative predictive model with four protein markers was developed for the differential diagnosis of these diseases. Nevertheless, pathway analysis of the disease-specific proteomes unveiled that Kallikrein-kinin system may play a crucial role in the pathophysiological mechanisms leading to brain damage in bacterial meningitis. Proteins taking part in this cellular process are proposed as putative targets to novel adjunctive therapies.

CONCLUSIONS

Comparative proteomics of cerebrospinal fluid disclosed candidate biomarkers, which were combined in a qualitative and sequential predictive model with potential to improve the differential diagnosis of pneumococcal, meningococcal and enteroviral meningitis. Moreover, we present the first evidence of the possible implication of Kallikrein-kinin system in the pathophysiology of bacterial meningitis.

Meningitis caused by Neisseria Meningitidis, Hemophilus Influenzae Type B and Streptococcus Pneumoniae during 2005-2012 in Turkey. A multicenter prospective surveillance study

Successful vaccination policies for protection from bacterial meningitis are dependent on determination of the etiology of bacterial meningitis. Cerebrospinal fluid (CSF) samples were obtained prospectively from children from 1 month to ≤18 years of age hospitalized with suspected meningitis, in order to determine the etiology of meningitis in Turkey. DNA evidence of Neisseria meningitidis (N. meningitidis), Streptococcus pneumoniae (S. pneumoniae), and Hemophilus influenzae type b (Hib) was detected using multiplex polymerase chain reaction (PCR). In total, 1452 CSF samples were evaluated and bacterial etiology was determined in 645 (44.4%) cases between 2005 and 2012; N. meningitidis was detected in 333 (51.6%), S. pneumoniae in 195 (30.2%), and Hib in 117 (18.1%) of the PCR positive samples. Of the 333 N. meningitidis positive samples 127 (38.1%) were identified as serogroup W-135, 87 (26.1%) serogroup B, 28 (8.4%) serogroup A and 3 (0.9%) serogroup Y; 88 (26.4%) were non-groupable. As vaccines against the most frequent bacterial isolates in this study are available and licensed, these results highlight the need for broad based protection against meningococcal disease in Turkey.

Proteome-based bacterial identification using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS): A revolutionary shift in clinical diagnostic microbiology

Rapid and accurate identification of microorganisms, a prerequisite for appropriate patient care and infection control, is a critical function of any clinical microbiology laboratory. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a quick and reliable method for identification of microorganisms, including bacteria, yeast, molds, and mycobacteria. Indeed, there has been a revolutionary shift in clinical diagnostic microbiology. In the present review, the state of the art and advantages of MALDI-TOF MS-based bacterial identification are described. The potential of this innovative technology for use in strain typing and detection of antibiotic resistance is also discussed. This article is part of a Special Issue entitled: Medical Proteomics.

The diagnostic value of cerebrospinal fluids procalcitonin and lactate for the differential diagnosis of post-neurosurgical bacterial meningitis and aseptic meningitis

OBJECTIVES

Distinguishing between post-neurosurgical bacterial meningitis (PNBM) and aseptic meningitis is difficult. This study aims to evaluate the combined diagnostic value of CSF procalcitonin and lactate as novel PNBM markers in hospitalized post-neurosurgery patients.

DESIGN AND METHODS

This study was performed using CSF samples, collected by lumbar puncture, from 178 PNBM-suspected patients enrolled in a retrospective clinical study. The levels of CSF procalcitonin and lactate were appropriately assayed and the combined diagnostic value of these markers was assessed using receiver operating characteristic (ROC) curves, a two by two table, and non-parametric tests.

RESULTS

Fifty of the 178 patients were diagnosed with PNBM, based on the clinical symptoms and laboratory results. These PNBM patients showed significantly elevated levels of CSF procalcitonin and CSF lactate compared with the non-PNBM group (p<0.001 for both). It was revealed that the cut-off values for the diagnosis of PNBM were: 0.075ng/mL (sensitivity, 68%; specificity, 73%) for procalcitonin and 3.45mmol/L (sensitivity, 90%; specificity, 85%) for lactate. A serial test combining the levels of these two markers showed decreased sensitivity (64%) and increased specificity (91%), compared with either marker alone. In contrast, a parallel test combining the levels of these both markers showed increased sensitivity (96%) and decreased specificity (65%), compared with either marker alone.

CONCLUSION

Our study shows that the combined use of CSF procalcitonin and lactate can reliably distinguish between PNBM and non-PNBM and can be included in the design of diagnostic approaches to circumvent the shortcomings of conventional methods.