Meningitis and encephalitis at the Abbassia Fever Hospital, Cairo, Egypt, from 1966 to 1989.

A total of 7,809 patients with meningitis or encephalitis were admitted to the Abbassia Fever Hospital in Cairo, Egypt from November 1, 1966 to April 30, 1989. The etiology was Neisseria meningitidis (mostly group A) in 27.3% of the patients, Mycobacterium tuberculosis in 19.7%, Streptococcus pneumoniae in 7.3%, and Haemophilus influenzae in 4.1%. Almost 27% of the cases had purulent meningitis but without detectable etiology; however, the epidemiologic data suggest that most of these had meningococcal meningitis. Encephalitis was suspected in 12.5% of the patients. Most of the meningococcal, pneumococcal, and Haemophilus cases occurred during the winter months. The number of meningococcal and culture-negative purulent cases per year reached a maximum three times during the 22.5 years of this study. There were more males than females in all etiologic groups, with the ratio for the total patient population being 1.6:1. The average age ranged between 11.7 and 16.5 years for all groups except for Haemophilus patients, who had a mean age of 2.5 years. The mortality rate was almost 55% for tuberculous patients and was approximately 40% for both pneumococcal and Haemophilus patients; it was 8.5% in patients with meningococcal disease.

Detection of IgM antibodies to Neisseria meningitidis group A polysaccharide in meningitis patients by direct and antibody capture enzyme-linked immunosorbent assays.

Serum specimens obtained from culture-positive group A meningococcal meningitis patients in Cairo, Egypt were tested for immunoglobulin M (IgM) antibodies to Neisseria meningitidis group A polysaccharide by direct and IgM capture enzyme-linked immunosorbent assays (ELISAs). Sera from patients with meningitis caused by other bacteria were used as negative control specimens. The IgM antibodies to this antigen were detected by direct ELISA in 93% of 58 specimens obtained from patients with group A meningococcal disease three or more days after hospital admission, and by IgM capture ELISA in 83% of 60 such specimens. Sixteen percent of 25 specimens obtained three or more days after admission from negative control patients were positive by direct ELISA, and 4% were positive by IgM capture ELISA. The correlation coefficient of the results with the two assays was 0.85.

A review of the treatment of bacterial meningitis.

This is review of our experience in the treatment of meningitis carried out at the Naval Medical Research Unit No. 3 (NAMRU-3), Cairo, Egypt since 1967. We have demonstrated that the serum and cerebrospinal fluid concentrations of ampicillin and its efficacy when used in the treatment of meningitis are comparable whether they are administered intravenously or intramuscularly. The third generation cephalosporin ceftriaxone was found to be very safe and effective when administered intramuscularly once a day in the treatment of the different types of acute bacterial meningitis. Aztreonam given intramuscularly was successful in the treatment of Gram-negative meningitis caused by multi-resistant organisms. The fatality rates and morbidity were significantly reduced in patients with meningitis when dexamethasone was given in conjunction with antibacterial chemotherapy.

Epidemiology, prevalence and clinical diagnosis of meningitis at Abbassia Fever Hospital, Cairo, 1966-1989.

The United States Naval Medical Research Unit No. 3 and the Abbassia Fever Hospital in Cairo, Egypt have together diagnosed and treated 7809 patients admitted to a meningitis ward since 1966. Aetiological diagnosis was based on clinical evaluation and laboratory studies. Marked increases in annual admissions in 1970-1972, 1980-1982 and 1987-1988 were related to increases in admissions due to meningococcal disease, while in 1977-1981 the increase was due to encephalitis related to Rift Valley fever. Better, rapid diagnostic procedures are needed to enable effective treatment to be given earlier and to reduce mortality rates.

Laboratory diagnosis of bacterial meningitis.

This overview summarizes studies conducted since 1970 on the laboratory diagnosis of bacterial meningitis at the Naval Medical Research Unit No. 3. These investigations demonstrated that counterimmunoelectrophoresis (CIE), agglutination of sensitized staphylococcal cells or latex particles, and enzyme-linked immunosorbent assay (ELISA) effectively detect and identify specific antigens in the cerebrospinal fluid of patients with meningococcal, pneumococcal, and Haemophilus meningitis. ELISA was the most sensitive of these methods and CIE the least sensitive. ELISA was also used to measure antibodies to meningococcal outer membrane protein antigens in patients. Finally, high rates of group A meningococcal nasopharyngeal carriage were found in group A meningococcal meningitis patients and populations associated with group A patients, but not in populations that were not associated with group A disease.

Evaluation of performance parameters of a membrane-based dot immunoassay for meningococcal polysaccharide.

Increasingly, membrane-based enzyme immunoassays are being developed as the preferred solid-phase enzyme immunoassay format. We describe the rate kinetics of a polyvinylidene difluoride membrane-based dot immunoassay for meningococcal group A polysaccharide. Antigen detection sensitivity decreased logarithmically with linear decreases in incubation time. The sensitivity of a 30-min assay (5-min incubation steps) was increased to nearly the level of the standard assay (1-h incubation steps) by increasing the concentration of assay reagents fourfold. These results support the idea that existing microtiter plate assays can be transferred to rapid dot immunoassay formats with little or no loss of sensitivity.

Serodiagnosis of typhoid fever in paediatric patients by anti-LPS ELISA.

Enzyme-linked immunosorbent assay (ELISA) and immunoblot analysis showed that up to 50% of the anti-typhoid antibody in sera from blood culture positive paediatric typhoid fever patients is directed against lipopolysaccharide (LPS) antigen. Anti-Salmonella typhi LPS ELISA was therefore compared to Widal agglutination for serodiagnosis of typhoid fever in paediatric patients. Sera from 38 paediatric control individuals were ELISA negative for anti-S. typhi LPS IgG; all but 2 of these specimens were negative for anti-S. typhi LPS IgM. Paediatric patients hospitalized with signs and symptoms of typhoid fever were separated into 4 groups and tested by ELISA with the following results: 46 patients negative by both culture and Widal agglutination tests, 48% positive for anti-S. typhi LPS IgG and 35% for anti-S. typhi LPS IgM; 22 negative by culture but with positive Widal titres, 82% and 68% positive respectively; 28 culture positive for S. typhi, 93% and 82% respectively; and 12 culture positive for Salmonella other than S. typhi, 92% and 92% respectively. These data suggest that anti-S. typhi LPS ELISA is a suitable assay for diagnosis of typhoid fever in children.

Use of the directigen latex agglutination test for detection of Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitidis antigens in cerebrospinal fluid from meningitis patients.

Cerebrospinal fluid specimens from 257 persons were tested for the presence of bacterial antigens by counterimmunoelectrophoresis and the Directigen meningitis test (Hynson, Westcott & Dunning, Div. Becton Dickinson & Co., Baltimore, Md.). The specimens were obtained from 162 patients with meningitis caused by Haemophilus influenzae type b, Streptococcus pneumoniae, or Neisseria meningitidis serogroups A and C and from 95 patients without bacterial meningitis or meningitis caused by other bacterial agents. Directigen detected H. influenzae type b antigen in 83% (69 of 83) of the specimens obtained from patients with H. influenzae disease, pneumococcal antigen in 77% (30 of 39) of the specimens from patients with pneumococcal disease, and N. meningitidis antigen in 93% (37 of 40) of the specimens from patients with disease caused by N. meningitidis serogroups A and C. The comparable figures for counterimmunoelectrophoresis were 66% (55 of 83), 79% (31 of 39), and 78% (31 of 40), respectively. No false-positive reactions were reported with the Directigen reagents. Nonspecific reactions (agglutination with more than one of the four Directigen latex reagents) were noted with five specimens. The nonspecific reactions were resolved in four of the five specimens by heating (100 degrees C for 3 min). The accumulated data demonstrate that the sensitivity of the Directigen meningitis test is better than or at least equivalent to the sensitivity of counterimmunoelectrophoresis for the detection of antigens in cerebrospinal fluid.

Enzyme immunoassay for detection of pneumococcal antigen in cerebrospinal fluid.

A solid-phase immunoassay utilizing horse antiserum against the C polysaccharide of Streptococcus pneumoniae and biotinylated rabbit antibodies to type-specific pneumococcal polysaccharides was developed to detect pneumococcal antigens in human body fluids and in broth cultures. Pneumococcal antigen could be detected in broth cultures of serotypes of S. pneumoniae containing as little as 10(2) to 10(3) organisms per ml. The assay system detected pneumococcal antigen in all 25 cerebrospinal fluid specimens obtained from patients with documented pneumococcal meningitis. There were no positive reactions noted in specimens from patients infected with Neisseria meningitidis group A or from patients without evidence of bacterial infection. The solid-phase enzyme immunoassay utilizing these reagents is a sensitive and specific assay for the immunodetection of a wide range of pneumococcal antigens.

Detection of Neisseria meningitidis group A, Haemophilus influenzae type b, and Streptococcus pneumoniae antigens in cerebrospinal fluid specimens by antigen capture enzyme-linked immunosorbent assays.

Antigen capture enzyme-linked immunosorbent assay was compared to coagglutination and counterimmunoelectrophoresis for the detection of meningococcal, Haemophilus, and pneumococcal antigens. Enzyme-linked immunosorbent assay detected 1 ng of purified meningococcal and Haemophilus polysaccharides per ml and 5 ng of pneumococcal polysaccharide per ml; coagglutination detected 20, 25, and 30 ng/ml, respectively, of these polysaccharides; and counterimmunoelectrophoresis detected 10, 50, and 60 ng/ml. Double-antibody sandwich-antiglobulin enzyme-linked immunosorbent assays, which employed antibodies produced in two animal species, differentiated 100% of the cerebrospinal fluid (CSF) specimens from meningococcal meningitis patients and 95% of the CSFs from Haemophilus patients from heterologous control CSFs. Double-antibody sandwich procedures, which use the same antiserum preparation for coating the wells of microtiter plates and for alkaline phosphatase-conjugated immunoglobulin, differentiated meningococcal CSFs from control specimens but were unable to effectively differentiate the Haemophilus or pneumococcal specimens from control CSFs. Coagglutination detected specific antigen in 92% of the meningococcal CSFs, 80% of the Haemophilus CSFs, and 92% of the pneumococcal specimens. The comparable percentages for counterimmunoelectrophoresis were 76, 95, and 71%.

Enzyme-linked immunosorbent assay with a monoclonal antibody for detecting group A meningococcal antigens in cerebrospinal fluid.

Hybridomas were produced from spleen cells of BALB/c mice immunized with a membrane preparation from Neisseria meningitidis group A strain 4402 and S194/5.XXOBU.14 myeloma cells. The hybridomas were screened for secretion of antibodies suitable for an enzyme-linked immunosorbent assay (ELISA) diagnostic for group A meningococcal meningitis. One hybridoma antibody, 3G7, was directed against the pilus protein. This antibody bound to all six lipopolysaccharide and protein group A meningococcal serotyping strains, as well as to meningococcal strains from serogroups C, W135, and Y, but not to a strain of Escherichia coli, Haemophilus influenzae type b, or to two or more strains of Streptococcus pneumoniae, Neisseria gonorrhoeae, and Salmonella typhi. The ELISA used on antibody, antigen, antibody-conjugate sandwich. Rabbit anti-meningococcal serum was the coating antibody for the antibody sandwich, cerebrospinal fluids contained the bacterial antigens, and 3G7-alkaline phosphatase conjugate was the detecting antibody. The monoclonal antibody conjugate ELISA system was able to detect group A meningococcal antigens in 21 of 25 cerebrospinal fluid specimens that were positive in an immune rabbit serum conjugate ELISA; cerebrospinal fluid samples from patients with Haemophilus meningitis served as the controls. Counterimmunoelectrophoresis detected meningococcal antigens in 16 of the same 25 cerebrospinal fluid samples.

Monoclonal antibodies against Neisseria meningitidis lipopolysaccharide.

A cell line producing monoclonal antibodies directed against a lipopolysaccharide component of Neisseria meningitidis group A has been established. These antibodies reacted with only one of three lipopolysaccharide serotyping strains of group A meningococci by coagglutination, enzyme-linked immunosorbent assay, and Western blotting techniques. A Western blot analysis showed that a NaOH digest of lipopolysaccharide was detectable by the serotype-specific antibody. The monoclonal antibodies cross-reacted with a group B meningococcal strain in an enzyme-linked immunosorbent assay. The immunoblotting analysis also showed that these antibodies reacted with the lipopolysaccharides of a group B meningococcus as well as Haemophilus influenzae type B, but not with the lipopolysaccharides of several strains of Salmonella typhi, Escherichia coli, Streptococcus pneumoniae, and Neisseria gonorrhoeae.

Rapid, economical diagnosis of enteric fever by a blood clot culture coagglutination procedure.

Coagglutination tests with Salmonella A, D, Vi, and polyvalent antiserum-sensitized staphylococcal cells were compared with conventional culture methods for detecting salmonellae in ox bile cultures of blood clots from enteric fever patients. The coagglutination tests appeared equally as effective as conventional subculture methods for detecting positive cultures (95% agreement). In addition, the coagglutination method yielded earlier results at reduced cost.

Diagnosis of human brucellosis with ELISA.

ELISA tests for total (IgG + IgM + IgA), IgG, and IgM anti-Brucella antibodies, which utilised only commercially available reagents, were used to diagnose human brucellosis. Assays for total antibodies in sera from 22 patients with confirmed acute brucellosis, 1 patient with probable acute brucellosis, and 3 patients with probable chronic brucellosis gave readings that were more than double those found in hundreds of control sera. All sera from patients with acute and chronic brucellosis had significantly elevated IgG levels. Although there were a few acute patients with IgM levels only slightly higher than those of some controls, most patients with acute disease could readily be differentiated from both the non-brucellosis patients and patients with chronic brucellosis by measuring macroglobulins. Both the IgG and IgM levels of sera from acute patients persisted for at least 8 months. The results of this show that ELISA is an excellent method for screening large populations for Brucella antibodies and for differentiation between the acute and chronic phases of the disease.

Cerebrospinal fluid and serum ampicillin levels in bacterial meningitis patients after intravenous and intramuscular administration.

28 patients with bacterial meningitis received ampicillin by the intramuscular (IM) route and 16 patients by the intravenous (IV) route. The mean cerebrospinal fluid (CSF) ampicillin levels were similar in the two groups 1 h after a dose given on the first or second day of treatment, but they were higher in the IM group on both days 4 h after a dose. CSF/serum ratios were similar in both groups but considerably higher at 4 h than at 1 h.

Detection of Neisseria meningitidis cell envelope antigen by enzyme-linked immunosorbent assay in patients with meningococcal disease.

Sera from various populations and cerebrospinal fluid (CSF) from meningitis patients were tested for Neisseria meningitidis cell envelope antigen by an enzyme-linked immunosorbent assay (ELISA) sandwich system. The minimum optical density (OD) for antigen detection in CSF was defined as the mean value obtained with specimens from a group of tuberculous meningitis patients plus two standard deviations. By this criterion, antigen was detected by ELISA in four of five CSF specimens from group A meningococcal meningitis patients. Very high ELISA values were obtained with sera from fulminating cases but control sera and sera obtained from meningococcal meningitis non-fulminating cases could not be clearly differentiated by this technique. The possible reasons for this are discussed. The results of this study show that as little as 15 ng/ml (protein) of cell envelope antigen can be detected by the ELISA sandwich test and suggest that the technique may be of value in clinical diagnosis of meningococcal disease.