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Concordance of cerebrospinal fluid latex particle agglutination test with CSF and blood culture among children with acute bacterial meningitis

Muhammad Khalid, Ali Faisal Saleem  ( Department of Pediatrics and Child Health, Aga Khan University Hospital. Karachi. )

Abstract

Madam, Acute Bacterial Meningitis (ABM) is potentially life threatening central nervous system infection, which is estimated to affect ~~ 5, 00,000 children worldwide with 10% mortality.1 Latex Particle Agglutination (LPA) is a rapid diagnostic test for identification of bacterial antigens in CSF in ABM.  It requires only 0.5-1.0 ml CSF to carry out the test, results are available in 10-15 minutes and it could be useful in the diagnosis of partially treated meningitis. Compared to CSF culture LPA had a sensitivity of 66.66%, specificity of 87.91%, positive predictive value (PPV) of 35.29% and negative predictive value (NPV) of 96.38%.2
We conducted a retrospective data analysis of 432 paediatric patients admitted at Aga Khan University Hospital (ERC # 3791-Ped-ERC-15) of age 1 month - 16 years, discharged with diagnosis of ABM (ICD-9 codes 320 and 320.9) between January 2012 - December 2014, aimed to evaluate the reliability and accuracy of LPA test in rapid diagnosis of ABM by comparative evaluation with CSF and blood cultures. Children with post-surgical meningitis, TBM, malignancy, absent CSF report (done outside) and neonates were excluded from the study. Finally 231 children were included in study. Data was collected on demographic variables and laboratory investigations.
Our study consisted of 146 males (63.2%). Median age was 41 months and median hospital stay was 4 days (range 1-48). Positive CSF culture in 7 cases included streptococcus species in three cases and one case of each corynebacterium species, enterococcus species, pseudomonas species and Acinetobacter species respectively. CSF LPA was positive in only 2 (1.32%) children (Table).



Both of these cases were under 1 year of age. LPA detected H. influenza and streptococcus pneumoniae in these cases whereas blood and CSF culture were negative. Only 23 (10.5%) of 219 blood cultures were positive. Thirteen (57%) of these cases were < 12 months of age. Gram negative micro-organisms [Salmonella, Klebsiella pneumoniae, Burkholderia cepacia and Acinetobacter] were identified in seven cases where as remaining cases were gram positive pathogens [Streptococcus and Staphylococcus (both aureus and non-aureus)].
In accordance to the study by Ghotaslou et al3 where CSF culture was positive in 3.97% of cases, our study had positive CSF culture in 3.03 % of the cases. LPA test in our study was positive in 1.32 % of cases whereas it was positive in 5.05% of cases from an Iranian study3 however study by Mishra et al4 showed positive rates of 19.3%. Sensitivity, specificity, PPV and NPV of LPA test was 0%, 98.51%, 0 % and 97.1% respectively in our study. Positive and negative predictive value (PPV, NPV) is the probability of the disease will be present or absent when screening test is positive or negative respectively.
Due to low yield and high cost LPA should not be routinely used as screening tool for diagnosis of acute bacterial meningitis. Test selection in ABM needs to be individualized on the basis of history, examination, vaccination status and prior use of antibiotics. No test can replace the utility of cultures.

Disclaimer:
None.
Conflict of Interest: None.
Funding Sources: Dr. Muhammad Khalid is trainee Fellow in Pediatric Infectious Diseases supported by Grant Number 1 D43 TW007585-01 from the National Institute of Health's Fogarty International Center.

References


1. Brouwer MC, Tunkel AR, van de Beek D. Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis. Clin Microbiol Rev. 2010; 23: 467-92.
2. Shenoy B, Biradar S. Latex Agglutination Test (LAT)-For rapid diagnosis of acute bacterial meningitis. Paed Infect Dis 2014; 6: 150-2.
3. Ghotaslou R, Farajnia S, Yeganeh F, Abdoli-Oskouei S, Rezaee MA, Barzegar M. Detection of acute childhood meningitis by PCR, culture and agglutination tests in Tabriz, Iran. Acta Medica Iranica. 2012; 50: 192.
4. Mishra B, Mahaseth C, Rayamajhi A. Latex agglutination test for early detection of causative organism in acute bacterial meningitis. J Nepal Paediatr Soc. 2013; 33: 34-8.


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