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Clinical
Microbiology
Accuracy
of
heparin
binding
protein:
as
a
new
marker
in
prediction
of
acute
bacterial
meningitis
Mona
Kandil
a,
Gihane
Khalil
a,
Eman
El-Attar
a,∗,
Gihan
Shehata
b,
Salwa
Hassan
caAlexandriaUniversity,MedicalResearchInstitute,ChemicalPathologyDepartment,Alexandria,Egypt
bAlexandriaUniversity,MedicalResearchInstitute,BiomedicalInformaticsandMedicalStatisticsDepartment,Alexandria,Egypt cMinistryofHealth,MinistryofHealthSpecializedHospital,Alexandria,Egypt
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:Received16November2017 Accepted29May2018
Availableonline17August2018 AssociateEditor:AfonsoBarth
Keywords:
Communityacquiredmeningitis Acutebacterialmeningitis Heparinbindingprotein CSFbiomarker
Serumbiomarker
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b
s
t
r
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c
t
Background:Cerebrospinalfluidbacterialcultureisthegold-standardforconfirmationof acutebacterialmeningitis,butmanycasesarenotcultureconfirmed.Antibioticsreduce thechanceofamicrobiologicaldiagnosis.ObjectivetoevaluateefficacyofHeparin-binding proteinindiagnosisofbacterialmeningitis.
Patients:30patientsdiagnosedwithacutebacterialmeningitis,30viralmeningitis,and30 subjectswithnormalCSFfindings.
Design:Diagnosis was basedon history, clinicalcriteria,CSFexamination, latex agglu-tination&culture,and sensitivitiesandresponsetotherapy. HBPwasmeasuredusing enzyme-linkedimmunosorbenttechniqueinbothserum&CSF.
Results:CerebrospinalfluidHBPlevelsaveraged0.82±0.3ng/mLincontrols,3.3±1.7ng/mL in viral and 174.8±46.7ng/mL in bacterial meningitis. Mean serum level was 0.84±0.3ng/mLinthecontrols,3.7±1.9ng/mLinviral,and192.2±56.6ng/mLinbacterial meningitis.BothHBPlevelsweresignificantlyhigherinpatientswithbacterialmeningitis. Cut-offsof56.7ng/mland45.3ng/mlincerebrospinalfluid&serumshowed100%overall accuracy.Eveninpatientswhoreceivedpriorantibiotics,remainedelevated.
Conclusion: SerumHeparin-bindingproteinservesasa non-invasivepotentialmarkerof acutebacterialmeningitiseveninpartiallytreatedcases.
©2018SociedadeBrasileiradeMicrobiologia.PublishedbyElsevierEditoraLtda.Thisis anopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/ licenses/by-nc-nd/4.0/).
Introduction
Meningitis isthe mostcommon infectious centralnervous systemsyndrome.Acutebacterialmeningitis(ABM)isa life-threateningneurologicalemergency.Itisoneofthe top10 causesofinfection-relateddeathworldwide.Ifleftuntreated,
∗ Correspondingauthorat:47SultanHusseinSt.,Alexandria,Egypt.
E-mails:eman.elattar@alexu.edu.eg,emanelattar2005@yahoo.com(E.El-Attar).
itsmortalitycouldapproach100%.1Evenwithcurrent
antibi-oticsandadvancedintensivecare,themortalityrateofthe disease is approximately 10%; and 30–50% ofits survivors livewith permanentneurologicalsequel followinghospital discharge. Theclinical distinction between viral and acute bacterial meningitis is difficult in the acute phase of ill-ness because the symptomsare oftensimilar. Community
https://doi.org/10.1016/j.bjm.2018.05.007
1517-8382/©2018SociedadeBrasileiradeMicrobiologia.PublishedbyElsevierEditoraLtda.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
acquiredmeningitisreferstobacterialmeningitiscausedby
Haemophilusinfluenzae(mostlytypeb), Streptococcus pneumo-niaorNeisseriameningitidis.These comprise70–90%ofABM cases.1,2
According to WHO guidelines, CSF (cerebrospinal fluid) analysis isessential to establish the diagnosis, distinguish bacterialfromviralmeningitis,and toidentifythe etiologi-calagent.3 Bacterial cultureisthegold-standard technique
forABM confirmation,due to its high specificity for iden-tification of the etiologic agent (WHO, 2011). However, approximately 50% of suspected cases are not culture-confirmed. Thus, clinical criteria, culture, Gram staining, and bacterial antigen testing of CSF as well as the clas-sical markers in CSF: CSF lactate, protein, glucose, white blood cell (WBC), and neutrophil count are used. Unfortu-nately,noisolatedlaboratorytesthasdistinguishedbacterial meningitisfrom asepticmeningitis with100%sensitivity& specificity; and the most accurate combination of clinical features to raise or lower suspicion of meningitis is still unclear.4,5
Potentialapplicationsofbiomarkersininfectiousdiseases includedistinguishingbacterialfromnonbacterialinfection, monitoring response to therapy, and predicting outcomes. Heparin-binding protein (HBP), also known as Azurocidin and Cationic Antimicrobial Protein (CAP37), is a positively charged37kDglycoproteinreleasedfromthesecretory vesi-cles and azurophilic granules of activated neutrophils in severe sepsis. Structurally, it belongs to a hematopoietic serine protease superfamily with antimicrobial function. It forms a part of the innate defenses of human neu-trophils.HBPiseasilyandrapidlymobilizedfrommigrating neutrophils.6
Theaim of this study is to evaluatethe role of serum and CSF heparin binding protein in diagnosis of bacterial meningitis,and itsefficacy indifferentiatingbacterialfrom non-bacterialmeningitis;inordertoverifythepossibilityof usingtheHBPininitialevaluationofABM.
Methods
Studysetting:Thepresentstudy wasconductedinthe Min-istryofHealth Specializedhospital, Alexandria,Egypt.Itis thelargesthospitalofitskindinAlexandria;atertiarycare facilityandacenterofexpertiseincareandmanagementof feverpatients.ItservesthepopulationofAlexandriacityand nearbygovernorateswithaconsiderablecaseloadthat war-rantstheaccumulationofasufficientnumberofcasesduring areasonableperiodoftime.
Studydesign:Cross-sectionalstudy.
Study population: the study population encompassed 90 patientswhowereadmittedtotheFeverHospitalin Alexan-dria, Egypt, and were clinically suspected to have acute meningitis end of2016 & early 2017. Diagnosiswas based onhistory,clinicalcriteria,andCSFexaminationcriteria.3,7–10
Accordingtodiagnosis andtherapeuticoutcome,thestudy populationwasclassifiedintothreegroups:GroupIincluded 30patientsdiagnosedwithABM,GroupII30 patientswere diagnosedwithnon-bacterial(mostlyviral)meningitis,and,
finally,GroupIIIincluded30subjectswithnormalCSF exam-inationfindings(controlgroup).
Inclusioncriteria:Patientswithmeningitisadmittedtothe MinistryofHealthSpecializedHospital.
Exclusion criteria: patients with tuberculous meningitis, brain space occupyinglesions, HIVinfection (orwho were onimmunosuppressivetherapy),chronicbacterial meningi-tis,post-surgicalmeningitis,andthosewithahistoryofhead trauma,wereexcludedfromthestudy.
Sample sizecalculation: aminimumsamplesizeof29for eachgroupwascalculatedtoachieve80%power;andtodetect differenceof0.219betweentheareaunderthecurveofthenull hypothesis(0.78)andthealternativehypothesisof(0.999)with asignificancelevelof0.05
Tools of data collection: the study follows the principles of the Declaration of Helsinki.Consequently, aftergaining approvalfrom:theEthicalcommittee,MedicalResearch Insti-tute, Alexandria University, Ministry of Health Specialized Hospital, andMinistryofHealth;signedinformedconsents were obtainedfromallpatientsortheirguardians, profess-ingtheiracceptancetoparticipateinthestudyandhavethe resultspublished.
Three tools were used to obtain relevant information: Interviewingquestionnaire,clinicalexamination,and inves-tigations.
- Interviewing questionnaire: an interview schedule was designedto collect relevantinformation from all eligible patientsortheirguardiansenrolledinthisstudy.The sched-ule included the followingitems: personal, past medical historyandpresentcomplaint.
- Clinicalexamination: complete clinical examinationof the studysubjectswasperformed.
- Investigations:alaboratoryworkupwasdone;CSFandblood samples were drawn simultaneously under aseptic pre-cautions. CSF was collected by the attending physician in sterile tubes for chemical, microbiological and cyto-logical examination. Biochemical examination included glucose, protein and lactate, which were determined in CSF supernatantsamples aftercentrifugationat 2000×g
for 5min. A wet preparation of CSF was used for total WBCs count. Gram stain for detection of bacteria and differential WBC count on CSF sediment was done. For CSFbacterialculture,CSFwas centrifugedat1000×gfor 10–15min to sediment bacteria, cultured on blood agar and chocolate agar plates,incubated for18–24h at37◦C inacandle-jar,andexaminedafter18–24h.Agglutination testingforH.influenzae, N.meningitidis,andS.pneumoniae
using the CSF supernatant for the detection of solu-ble bacterial antigens(capsular polysaccharide)was also done.
For serum heparinbindingprotein, wholevenous blood was drawn from each subject. Blood was allowed to clot for 20minatroom temperature, centrifuged andaliquoted at −20◦C for the determination of the concentrations of
serum HBP, using Enzyme Linked Immunosorbant Tech-nique (Glory science Co., Ltd, Hangzhou, China). Serum & CSF HBP were measured according to the manufacturer’s instructions.11
Table1–CharacteristicsofthestudysampleandHBPlevelsinCSFandserum.
Characteristics Bacterialgroup Viralgroup Controlgroup Total
n=30 n=30 n=30 n=90 Gender Male 19(63.3%) 18(60)% 12(40%) 49(54.4%) Female 11(30.6%) 12(40)% 18(60)% 41(45.6%) Ageinyears Mean±SD 24.7±14.7 24.7±14.8 24.9±14.3 24.9±14.5 (Minimum–maximum) (1.5–50) (1.0–49) (1.5–50) (1.0–50) Pre-admissionantibiotic 25(83%) 27(90%) 24(80%) 76(84.4%) CSFHBPlevelinng/ml Mean±SD 174.8±46.7 3.3±1.7 0.82±0.3 (Minimum–maximum) 56.7–295 1.30–7.5 0.31–1.8 SerumHBPlevelsinng/ml Mean±SD 192.2±56.6 3.7±1.9 0.84±0.3 (Minimum–maximum) 45.3–289 1.1–7.6 0.4–1.51
Statisticalanalysis:was performedusingIBMSPSS soft-warepackageversion20.0.
- The qualitativevariables were summarizedby frequency andpercentage.Chisquaretestwasusedtotestfor asso-ciation between the type of meningitis and the other qualitativevariables.MonteCarlotestwasusedwhenmore than20%oftotalcellshadexpectedcellcounts<5. - Thedistributionsofquantitativevariablesweretestedfor
normalityusingKolmogorov–Smirnovtestandrevealed nor-maldatadistribution;andparametrictestswereapplied. - Thequantitativevariablesweresummarizedbythemean
and standard deviation. One-way ANOVA was used for Comparisonsofgroupdifferencesregardingthecontinuous variables.Correlationsbetweenquantitativevariableswere assessedusingPearsoncorrelationtechnique.
The Receiver Operating Characteristic (ROC) curve was usedtoevaluateaccuracyofHBPmarkerinpredictionof bac-terialmeningitis.Areaunderthecurvevaluesisreportedwith the95%confidenceinterval(CI).Allaccuracymarkerswere calculated:Sensitivities, specificities, positive and negative predictivevalues.Significanttestresultswerequotedas two-tailedprobabilities.Significanceoftheobtainedresultswas judgedatthe5%level(p≤0.05).
Results
CharacteristicsofthestudysampleandHBPlevelsinCSFand serumareillustratedinTable1.CSFHBP&serumHBPlevels werebothsignificantlyhigherinpatientswithacutebacterial meningitisthaninpatientswithviralmeningitisandcontrols. ThissuggeststhepotentialroleofbothCSF&serumHBPin distinguishingbetweenacutebacterialandviralmeningitis (p<0.01)(Fig.1).
Table2andFig.1showtheaccuracymeasures(atcutoff pointwithhighestsensitivityandspecificity)ofthe conven-tionalCSFparametersandHBPasanewmarker.Fordiagnosis ofbacterialmeningitis,theoverallaccuracyofCSFWBCsata cutoffof877.5cells/cmm,CSFneutrophilsatacutoffof59%, CSFproteinatacutoffof45.5mg/dl,CSFglucoseatacutoff
of39.5mg/dl,andthatofCSFlactateatacutoffof29.5mg/dL were:91.1%,99.7%,84.6%,82.5%,and92.7%respectively.
AcutoffpointofCSFHBPlevelat56.7ng/mlshowed100% sensitivityandspecificity;positiveandnegativepredictive val-uesof100%;andoverallaccuracyof100%.Atacutoffpointof 45.3ng/mlserumHBPalsoshowed100%sensitivityand speci-ficity; positive and negativepredictive valuesof 100%; and overallaccuracyof100%.Areasunderthecurvewere1.0for bothCSFand serumHBP;whichwerehigherthanallother investigatedparameters(Fig.1).
Table3illustratesahighlysignificantpositivecorrelation betweenCSFHBP, serumCSFandotherCSFfindings;WBCs, neutrophils percent,protein,lactateand decreasedglucose levels.
Lastly,Fig.2showsahighlysignificantpositivecorrelation betweenCSFand serumHBPlevels (r=0.93,p=0.000)inthe threegroups(Fig.2).
Discussion
Adverse effects oflumbar puncture include headache and backache. Complications may also occur in limited cases such as cerebral herniation, intracranial subdural hemor-rhage,spinalepiduralhemorrhage,andcranialandsubdural hematomasfromdecreasedCSFpressure.Mostimportantly, thereisanumberofsituationswhereLPmaybe contraindi-cated incasesatthe age of60or older,or casessuffering from:coagulopathies,immunocompromisedstate,historyof centralnervoussystemdisease,seizureandlocalinfectionat the puncture siteinmasslesions,andventricular obstruc-tioncausingraisedintracranialpressureandbrainabscess.12
Hence,alessinvasivesample(asbloodserum),toaidoreven replaceLPforthediagnosisandfollowupofmeningitis,would beofagreatbenefit;notonlytothepatientsbutalsoto physi-ciansandclinicallaboratories.
Inthisstudy,all30patientswithpositiveCSFfindingsin ABMgrouphadelevatedserumHBPlevels(192.2±56.6ng/mL). Consideringthesignificantmorbidityassociatedwithlumbar punctureandcontraindicationtoperformaCSFtapping,the positivecorrelationbetweenCSFandserumHBPlevelsmay furthersupportthepotentialuseofserumHBPasadiagnostic
ROC Curve
1 - Specificity
Diagonal segments are produced by ties.
Sensitivity
Source of the Curve WBCs /mm3 Neutrophills % of total wbcs
CSF protein (mg/dl) CSF lactate (mg/dl) Heparin Binding Protein in CSF (ng/ml) Heparin Binding Protein in Serum (ng/ml) Reference Line 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0.0 0.0
Fig.1–Receiveroperatorcharacteristicscurveofcerebrospinalfluidtotalwhitebloodcells,%neutrophils,protein,lactate andserumHeparinbindingproteininpredictionofbacterialmeningitis.
Table2–AccuracymeasureswiththecutoffpointsofHBPandoldmarkersinpredictionofbacterialmeningitis. Biomarker Cutoff Sensitivity Specificity Overallaccuracy(areaunderthecurve95%C.I) pvalue
CSFWBCs 877.5cells/mm3 63.3% 100% 91.1%(85.1–97.1%) 0.000 CSFneutrophils% 59% 100% 97% 99.7%(99.1–100%) 0.000 CSFprotein 45.5mg/dl 83.3% 70% 84.6%(76.2–93%) 0.000 CSFGlucose 39.5mg/dl 50% 100% 82.5%(71.7–92.8) 0.000 CSFLactate 29.5mg/dl 90% 87% 92.7%(86.1–99.4%) 0.000 CSFHBP 56.7ng/ml 100% 100% 100% 0.000 SerumHBP 45.3ng/ml 100% 100% 100% 0.000
Table3–CorrelationbetweenCSFandSerumHBPlevelsandCSFtraditionalmarkers.
TraditionalCSFmarkers CSFHBP SerumHBP
CSFWBCscount/mm3 r=0.349,p=0.001 r=0.295,p=0.005
CSFneutrophils%oftotalCSFWBCs r=0.907,p=0.000 r=0.916,p=0.000
AbsoluteCSFneutrophilscount/mm3 r=0.347,p=0.001 r=0.295,p=0.005
CSFglucose(mg/dl) r=−0.583,p=0.000 r=−0.617,p=0.000
CSFProtein(mg/dl) r=0.574,p=0.000 r=0.589,p=0.000
CSFLactate(mg/dl) r=0.662,p=0.000 r=0.687,p=0.000
markerinsubstitutionoftraditionalCSFanalysis.Therefore, serumHBPmaybeusedinconfirmingorrulingoutthe diag-nosisofclinicallysuspectedbacterialmeningitis,especially incaseswherelumbarpunctureiscontraindicated.Also,the possibilityofreplacingfollowupLPwithserumHBPisworth furtherinvestigation.
Inmanyclinicalsettings,involvingpatientswithclinical suspicion ofbacterial meningitis, antibiotics are instituted beforelumbarpuncture;reducingthe chanceofa microbi-ological diagnosis. Eighty three percent of our patients in thebacterialgroupreceivedantibiotics48–72hbeforelumbar puncture. However, these patients still maintained signifi-cantlyelevatedCSFandserumHBPlevels.
Inthis study,meningitiswasconfirmedbybacterial cul-ture,Gramstainingand/oragglutinationtesting,onlyin16.7%
ofpatients.However,theremaining83.3%ofpatientsinthe bacterialgroupwerediagnosedasbacterialaccordingto: pos-itivetraditionalCSFlaboratoryfindings,clinicalfindings,and response to treatment. The low detection rates ofculture, Gramstainingandagglutinationcomparedcouldbeexplained by low concentration of pathogens or empirical antibiotic treatmentpriortosamplecollectionwhichreducesthe diag-nosticsensitivityofthesetests. Ithasalsobeenshownfor patientsofbacterialgroupthatCSFlevelsofprotein(in16.7% ofpatients),glucose(in50%ofpatients),andlactate(in10% ofpatients)couldnotdifferentiatebetweenbacterialandviral meningitis;denotingtheneedofadditionalsensitiveand spe-cificmarkers.
As a granule-associated protein, HBP is rapidly mobi-lized frommigratingpolymorphonuclear leukocytes.Itacts
300.00
( r = 0.928,P = 0.000)
Hepar
in Binding Protein in CSF (ng/ml)
Heparin Binding Protein in Serum (ng/ml)
250.00 200.00 150.00 100.00 50.00 .00 .00 50.00 100.00 150.00 200.00 250.00 300.00
Fig.2–CorrelationbetweencerebrospinalfluidandserumHBPlevels.
as a chemoattractant, an activator of monocytes and macrophages, and induces vascular leakage and edema formation.ThereleaseofHBPistriggeredbyligationof neu-trophilic 2-integrins; a process that may be initiated by bacteria.Theoveralloutcomeispowerfulvascularleakage.13
WhentheseeffectsareappliedtothecaseofABM, neutrophil-derivedHBPproductioncouldresultfromtheinflammatory responsetobacterialinfectionandcouldhaveamajorrolein theresultantbraininjuryandbrainedemainABM.
HBPwas proposedasamarkerofbacterialinfection for earlydetectionofpatientsinthe emergencydepartmentat riskofdevelopingseveresepsisandsepticshock.It demon-stratedsignificantpredictivevaluesofelevatedlevelsofHBP inbloodofpatientswithseveresepsisand septicshock as comparedtoHBPlevelsinpatientswithnoninfectiouscritical illness,andascomparedtoothermarkers.ElevatedHBPlevels (>30ng/ml)werefoundin80%ofthepatientswhileelevated procalcitonin levels (>0.5ng/ml)were detectedin 59%, ten andahalfhours(median)beforedevelopingseveresepsis.14
Linderet al.(2012)15foundsignificantlyhigherplasmaHBP
inpatientswithseveresepsisorsepticshock,ascompared to patients with a non-septicillness in the intensive care unit.HBPwasassociatedwithseverityofdisease,andan ele-vated HBP atadmission was associatedwith an increased risk of death. They recommended repeated HBP measure-ment in the ICU may help monitor treatment and predict outcome in patients with severe infections. Holub, Beran (2012),16andBentzer(2016)17reportedsimilarfindings.Other
studies present the role of HBP as a serum biomarker of bacterialinfections.13,18–20Linder(2015)21 suggestedHBPas
thebestpredictorandanearlyindicatorofinfection-related organdysfunction;andastrongpredictorofdisease progres-sionto severe sepsis within72h inpatients presenting at theemergencydepartment.Finally,in2017Fisher& Linder acknowledgethatHBPhasamajorroleinthepathophysiology
ofseverebacterialinfectionsand,thus,representsapotential diagnosticmarkerandatargetforthetreatment.22Another
study for them laterthat year statesthat elevated plasma HBPisassociatedwithdevelopmentofsepsis-inducedacute kidneyinjury.23
Presumably, HBP was scarcely investigated in CSF of patients. Linder et al. (2011)11 analyzed CSF samples for
the concentrations of HBP, lactate, protein, glucose, neu-trophils, and mononuclear cells. HBP levels in CSF were significantlyhigher (p<0.01) inpatientswith ABM(median 376ng/mL, range 12–858ng/mL) than in patientswith viral meningitis(median4.7ng/mL,range3.0–41ng/mL),orcontrol patientswithnormalCSFcellcount(median3.5ng/mL,range 2.4–8.7ng/mL).TheysuggestedaCSFHBPcutoffconcentration exceeding20ng/mLtodiagnoseABM;withsensitivity100%, specificity99.2%,andpositiveandnegativepredictivevalues of96.2%and100%.TheareaundertheROCcurvefor heparin-bindingproteinwas0.994,whichwashigherthanthatforthe other investigatedparameters. Linderetal. concludedthat elevatedCSFlevelsofHBPcoulddistinguishbetweenpatients withacutebacterialmeningitisandpatientswithother cen-tralnervoussysteminfections.Wenotetherelativelysmall numberofpatientsincludedintheirstudy(41bacterial menin-gitispatientsand10viralmeningitispatients).Theresultsin thisstudyconcurwithandconfirmtheseresults.Moreover, thepresentstudytookastepfurtherasitisthefirststudyto investigateserumHBPinmeningitisandtocorrelatebetween CSFandserumHBP. Thestudyalsolocatesaweakpositive correlationbetweenCSFHBPandCSFpolymorphonuclearcell counts.ThiswasalsonotedbyLinderetal.;and they sug-gestedthatHBPlevelprobablyreflectsthenumberofactivated neutrophilsratherthantheabsoluteneutrophilcount.
PCRtestingismoresensitivethanCSFculture,particularly inpatientswhoreceivedpreviousantimicrobials.CSF bacte-rial culturerequiresthatlaboratoriesreceivelivingbacteria
whichisquietrestrictingtakingintoconsiderationthefragility ofthethreecausativebacteriaofcommunityacquired menin-gitis.However,PCRcannotberoutinelydoneinthediagnosis ofevery caseof bacterial meningitis;it is more expensive andnotavailableinresourcelimitedsettings,asisthecase indevelopingcountries. ThereforePCRisnotusually avail-ableforroutinecasemanagement;itcanberetrospectively usedinsurveillancepurposesforadaptingthemost appropri-atepreventivestrategy.24Inpatientswithsuspectedbacterial
meningitis,empiricaltherapyshouldnotbedelayedformore thanonehourwhileawaitingdiagnostictesting.Inthe mean-time,HBPtestingcanofferarapid,affordabletooltodetect patientswithearlybacterialmeningitisorpatientswhohave beenpartiallytreated.
Giventhe lackofspecificityofclinical findings,the key tothediagnosis ofmeningitisisthe evaluationofCSF. Ini-tiationofantimicrobialsbefore lumbarpuncture decreases theyieldofCSFculture;Gramstaining;CSFpleocytosis;the likelihoodofalowCSFglucoselevel;andthedegreeof ele-vationofCSFproteinandofCSFlactate.Moreover,patients with early bacterial meningitis might not have the classi-cal positive CSF findings of bacterial meningitis. However, Heparin-bindingproteinisapromisingnewbiomarkerthat might assist with early identification of bacterial menin-gitis as well as partially treated bacterial meningitis. It is recommend to have further studies on larger scales. CSF HBP level ≥56.7ng/mL; and serum HBP level ≥45.3ng/mL should prompt empirical therapy for bacterial meningitis while awaiting results of CSF culture or even molecular assays.
CSF and serum HBP were both significantly higher in patientswithacutebacterialmeningitisthaninpatientswith viralmeningitisandcontrols;despitetheintakeofantibiotics. CSFHBPlevelat56.7ng/ml,andserumHBPlevelat45.3ng/ml showed100%sensitivityandspecificity,andpositiveand neg-ativepredictivevaluesof100%,andoverallaccuracyof100% forthisparameter.
Ourstudyshedslightontheexcellentdiagnostic perfor-manceofHBPinthediagnosisandpossiblyfollowupofacute bacterialmeningitis.SinceCSFHBPwashigherthanserum HBPinABM patients,it issafetoassume thatHBPis pro-ducedlocallyintheCSFandisnotcomingfromasystemic source.ThecorrelationofserumandCSFlevels&otherCSF parameterssuggeststhatserumlevelsofHBPcanbeusedas anon-invasivetestofABM.However,duetothelackof speci-ficity,serumHBPcannotconfidentlyreplacethefirstCSFtap. HighlevelsofserumHBPwhenusedalonecouldalsoindicate systemicbacterialinfection&sepsis.Thustheuseofserum
HBP(alonewithoutCSFHBP)indiagnosisofABMhastobe incontextwithclinicalfindings.WesuggestthatserialHBP measurementscouldbefurtherstudiedasareplacementfor thesecondCSFtapinthefollowupofABM.
MeasuringHBPinCSFfrompatientswithsuspected menin-gitiscouldimprovethediagnosticaccuracyindifferentiating betweenbacterialandviralmeningitis,therebyallowingthe cliniciantostartadequatetreatmentearlier;especiallyin sit-uationsorplaceswhenthetimeandresourcesarelimited. Resultsofthisstudypointoutthepossibilityofconsidering
serum HBPas a diagnostic markerin substitution of tradi-tionalCSFanalysisinconfirmingorrulingoutthediagnosisof
communityacquiredABM;especiallywithabsoluteand rela-tivecontraindicatedlumbarpuncture.
HBPcouldbeapromisingbiomarkerthatmightassistwith earlyidentificationofbacterialmeningitisaswellaspartially treated bacterial meningitis.HBPcould be introduced asa routinetestforpatientswithABM;especiallywhenkitsfor its determinationareavailableonacommercialautomated basisandnotonlyforresearchstudies.Theseresultswarrant evaluationindifferentpopulationsandlargerscale.Further research forserial measurementsofHBPplasma levelsfor closemonitoringofcriticallyillmeningitispatients,instead ofrepeatedlumbarpuncturewhichiscurrentlyusedinfollow upofacutebacterialmeningitiscases,isrecommended.
Disclosures
• Thisworkwasself-fundedbytheauthorsthemselvesand nofundingsourcesmadeanycontributiontoit.
Dataset
• El-Attar, Eman; Khalil, Gihane; Shehata, Gihan; Kandil, Mona; Hassan, Salwa (2017), “Heparin Binding Pro-tein in Acute Bacterial Meningitis”, Mendeley Data, v2 https://doi.org/10.17632/g5c9w4pw3r.2
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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