Evaluation of a newly developed ELISA against Widal, TUBEX-TF and Typhidot for typhoid fever surveillance.

INTRODUCTION: Typhoid fever is endemic in many parts of the world and represents a major cause of acute febrile illness (AFI). Rapid and accurate laboratory methods for diagnosis of this disease are needed for both patient care and surveillance situations. METHODOLOGY: Serum samples were collected from AFI patients and used to evaluate the performance of a newly developed ELISA assay that uses a mixture of somatic and flagellar antigens to detect the total antibody response against Salmonella enterica subspecies enterica serovar Typhi (S. Typhi) infection. The levels of Ig isotype response (IgG, IgM and IgA) were also evaluated, and results were compared to those of TUBEX-TF and Typhidot commercial kits.  RESULTS: Of 234 culture-confirmed typhoid patients, the total Ig ELISA diagnosed 93% compared to 71% using Widal test. This sensitivity level (93%) is higher than that observed for the individual Ig ELISAs (IgG 75%; IgM 79%; IgA 57%) and the commercial tests TUBEX-TF (75%), Typhidot IgM (63%) and Typhidot IgG (28%). An agreement of 78% was achieved between the total Ig ELISA and Widal test. The average specificity of the ELISA was 96%. Using ELISA, up to 200 samples can be tested per run with cost per test at US$0.20. CONCLUSIONS: The developed ELISA shows superior sensitivity and specificity, when compared to Widal, TUBEX-TF and Typhidot assays, is more cost effective and allows higher throughput. This method is highly recommended for active surveillance studies or outbreak investigations of typhoid fever.

Isolation of cryptococcus, Candida, Aspergillus, Rhodotorula and nocardia from meningitis patients in egypt.

Meningitis occurs throughout Egypt and is largely attributed to bacterial pathogens, but there is little information on fungal etiologies of meningitis. We, therefore, investigated fungal infections among Egyptian patients with acute and subacute meningitis who tested negative for bacterial and viral agents. A total of 1000 cerebrospinal fluid (CSF) samples collected from nine governorates of Egypt during 1998-2002 were initially stained with Gram's, India ink, and lacto-phenol cotton-blue stains, and examined under light microscope to detect fungal elements. All CSF samples were cultured on brain heart infusion, Wickerham and Staib agar media for fungus isolation. CSF with suspected Cryptococcus neoformans infections were also tested by latex agglutination test for antigen detection. Species identification of selected isolates was carried out at the Mycotic Diseases Branch, CDC, Atlanta, Georgia, USA. Fungal agents were detected microscopically and by culture in 17 of 1000 (1.7%) CSF samples tested. Ten of 17 were identified as C. neoformans var grubii (serotype A), 4 as Candida albicans, and one each of Aspergillus candidus, Rhodotorula mucilaginosa (rubra) and Nocardia spp (actinomycetes). Out of the 17 cases with fungal CSF infection, 8 died (Cryptococcus-3, Candida-2, Aspergillus, Rhodotorula and Nocardia) and 2 suffered neurological sequelae. Of the 10 cryptococcal meningitis patients, 4 were HIV positive and one was diagnosed with lymphoma. To our knowledge, this is the first study on isolation of fungi other than Cryptococcus from CSF of Egyptian patients with acute/subacute meningitis. Consideration must now be given to cryptococcosis and candidiasis as potential etiologies of meningitis in Egypt.

Differentiation of tuberculous meningitis from acute bacterial meningitis using simple clinical and laboratory parameters.

Tuberculous meningitis (TBM) is still a major cause of serious illness in many parts of the world. The newer diagnostic tests and neuroimaging methods are unlikely to be available in many developing countries. We attempt to identify simple parameters for early diagnosis. A retrospective study was performed to compare the clinical and laboratory features of cultured-confirmed, TBM (134) and other bacterial meningitis (709). Features independently predictive of TBM were studied by multivariate logistic regression to develop a diagnostic rule. Six features were found predictive: length of clinical history >5 days, headache, total cerebrospinal fluid (CSF) white blood cell count of <1000/mm3, clear appearance of CSF, lymphocyte proportion of >30%, and protein content of >100 mg/dL. Application of 3 or more parameters revealed 93% sensitivity and 77% specificity. Applying this diagnostic rule can help in the early diagnosis of TBM, in both children and adults.