Antigen analysis of group A streptococcus strain, "Matsuyama 2166", which had been typed as T12-28 (by the T-agglutination method), MNT (nontypeable by the M-precipitation method) using conventional typing sera was examined by the precipitation and precipitation absorption technique. The prevalence of group A streptococci, typed under the name "Matsuyama 2166" was also investigated. The results were as follows: 1) The strain "Matsuyama 2166" is OF (Opacity Factor) (+) and its serological components consist of M "Matsuyama 2166" antigen, which is unique in our collection of M-types, and T28 antigen as a major antigen along with T12 as a minor. 2) Out of the group A streptococci typed as MNT, 96.6% of the streptococci were types as T12-28 and 96.5% of T28 by conventional typing sera were strains to be typed as M "Matsuyama 2166" using the newly prepared M "Matsuyama 2166" typing serum, suggesting the great advantage to M-typing rate of T28 strains. 3) Group A streptococcus M "Matsuyama 2166" was also found in isolates from Thailand or Malaysia. It is interesting that T-types found in those isolates seems to be a little different from the T-types isolated in Japan. These results showed that there was the difficult problem when we did the speculation of M-type from the result of T-type.
Enzyme Linked Immunosorbent Assay (ELISA) is a standard assay that has been used widely to validate the presence of analyte in the solution. With the advancement of ELISA, different strategies have shown and became a suitable immunoassay for a wide range of analytes. Herein, we attempted to provide additional evidence with ELISA, to show its suitability for multi-analyte detection. To demonstrate, three clinically relevant targets have been chosen, which include 16kDa protein from Mycobacterium tuberculosis, human blood clotting Factor IXa and a tumour marker Squamous Cell Carcinoma antigen. Indeed, we adapted the routine steps from the conventional ELISA to validate the occurrence of analytes both in homogeneous and heterogeneous solutions. With the homogeneous and heterogeneous solutions, we could attain the sensitivity of 2, 8 and 1nM for the targets 16kDa protein, FIXa and SSC antigen, respectively. Further, the specific multi-analyte validations were evidenced with the similar sensitivities in the presence of human serum. ELISA assay in this study has proven its applicability for the genuine multiple target validation in the heterogeneous solution, can be followed for other target validations.
Infection with Chlamydia trachomatis results in the formation of a variety of antibodies with group, species, subspecies and serovarspecificity. Sera from patients with genital tract infections often show broad reactivity in serological tests. This may be due to the presence of cross-reacting antibodies, repeated infections by different serotypes or concurrent genital and respiratory infections by different chlamydial species. Other factors contributing to difficulties in interpretation include how antibody titres in acute mucosal infections, the occurrence of latent infections and reactivations, and the persistence of IgG which does not allow the differentiation of past from current infections. For these reasons, serology alone is inadequate for the diagnosis of uncomplicated lower genital tract infections. In upper genital tract infections, however, because of difficulties with sampling from the infected site, a positive serology may be the only indications of chlamydial involvement. This paper discusses the principles of chlamydial antibody assays, difficulties with their interpretation and their role in the diagnosis of upper and lower genital tract infections.
Forty-four serum samples of various reactivities to rickettsial antigens demonstrated by the indirect immunoperoxidase technique were tested with INDX Dip-S-Ticks (INDX Integrated Diagnostics Inc., USA) Kit for the detection of tick borne diseases. The kit utilised Rickettsia rickettsii the causative agent of Rocky Mountain spotted fever (RMSF) as antigens. The samples positive for endemic typhus were also tested against R. typhi, the agent for endemic typhus by the same method. The aim of this study was to determine the extent of cross-reactivity of R. rickettsii with rickettsial infections in Malaysia. Nine out of 12 tick typhus, 4 out of 10 scrub typhus and 4 out of 12 endemic typhus samples cross reacted with R. rickettsii. Ten out of 12 endemic samples were positive with R. typhi by the same method. From the study, we concluded that the INDX Dip-S-Ticks Kit can be used as a rapid screening test to detect endemic and tick-borne rickettsial infections in Malaysia but a second serological test is strongly recommended on all weakly reactive cases.
The usefulness of counterimmunoelectrophoresis (CIEP) and coagglutination (COAG) methods in the diagnosis of bacterial meningitis was evaluated. Out of the 31 cerebrospinal fluid (CSF) specimens which had a cell count of >5 x10^6 wbc/l and were negative on gram stain and culture, pneumococcal antigens were detected in four specimens and Haemophilus influenzae type b antigen was detected in one specimen by both the methods. No false positives were detected in 10 specimens obtained from cases of febrile fits whose CSF showed no evidence of meningitis. One CSF sample, from which Klebsiella spp. was isolated, cross reacted with the meningococcal polyvalent group A-D antiserum in the CIEP test. From this study we found that these methods are rapid, simple and useful adjunctive tests In the diagnosis of bacterial meningitis, especially in the partially treated cases.
Current studies were undertaken to determine the presence of a specific antigenic protein on the outer membrane of Salmonella typhi. Immunoblot analysis using sera from patients with fevers revealed that the 50 kD band was specifically recognized only by typhoid sera. The 50 kD band located on the outer membrane is protein by nature and is not a Vi (capsular), dH (flagellar), or O9 (somatic) antigen of S. typhi. These results indicate the usefulness of the specific antigen in the development of a serodiagnostic test for typhoid fever since antibodies of both the IgM and IgG class responses were obtained.
One hundred and fourteen Rickettsia tsutsugamushi isolates, recovered from febrile patients in central Peninsular Malaysia, were antigenically analyzed by direct immunofluorescence using eight prototype strains. Twenty-nine antigenic types were detected. The TA763, TA716, Karp and TA686 strains were the most common and occurred singly or in combination with each other or other strains in 86% of the isolates.
Diagnosis of active mycobacterial disease in orangutans (Pongo pygmaeus) has been impeded by high levels of non-specific intradermal skin test reactivity to mycobacterial antigens. This may be due in part to cross reactivity between antigens, tuberculin concentrations used or other species-specific factors. Antigen 85 (Ag85) complex proteins are major secretory products of actively growing mycobacteria, and measurement of serum Ag85 could provide a method for determining active mycobacterial infections that was not dependent on host immunity. Serum Ag85 was measured by dot-immunobinding assay using monoclonal anti-Ag85, purified Ag85 standard and enhanced chemiluminescence technology in coded serum samples from 14 captive orangutans from a zoo in Colorado, 15 semi-captive orangutans in Malaysia, and 19 free-ranging wild orangutans in Malaysia. Orangutans from Colorado (USA) were culture negative for Mycobacterium tuberculosis and M. avium, although all had laboratory suspicion or evidence of mycobacterial infection; median serum Ag85 was 10 microU/ml (range, <0.25-630 microU/ml). Of the semi-captive orangutans, six were skin test reactive and two were culture positive for M. avium on necropsy. Median serum Ag85 for this group was 1,880 microU/ml (0.75-7,000 microU/ml), significantly higher than that of Colorado zoo or free-ranging Malaysian orangutans. Median serum Ag85 in the latter group was 125 microU/ml (range, 0.75-2,500 microU/ml). These data suggest that suggest that additional studies using more specific reagents and more samples from animals of known status are appropriate.
IgM and IgG based ELISA systems were developed using the culture filtrate antigen (CFA) of Burkholderia pseudomallei. The assays were evaluated using 95 sera from 66 septicemic cases and 47 sera from 20 cases with localized melioidosis. In addition 65 sera from culture negative cases that were also serologically negative for other endemic infections clinically suspected of melioidosis were included. These were compared with sera from 260 non-melioidosis cases, 169 sera from individuals with high risk of acquiring the infection and 48 sera from healthy controls. The IgG-ELISA was 96% sensitive and 94% specific. All sera from cases with septicemic and localized infections and 61 of 63 sera from clinically suspected melioidosis cases were positive for IgG antibody. The geometric mean titre index (GMTI) values of IgG antibody in melioidosis cases were significantly higher (p < 0.0005) compared to that of healthy subjects, high risk group and subjects with non-melioidosis infections. The sensitivity and specificity of IgM ELISA was 74 and 99% respectively. The GMTI value of IgM antibody in the sera of melioidosis cases was significantly higher as compared to that of non-melioidosis disease controls (p < or = 0.001). These results demonstrate that the detection of IgG is a better indicator of the disease in the diagnosis of melioidosis.
A chromatographic immunoassay cholera antigen detection kit, the Cholera Spot test, was evaluated. The test was found to be specific with a sensitivity of 10(6) cfu/ml for the direct detection of V. cholerae in simulated stool specimens and 10 cfu/ml in simulated cotton-tipped swab specimens after overnight incubation in alkaline peptone water. This enables early recognition of cholera cases and their contacts so that prevention and control measures can be promptly instituted.
A case of respiratory infection in a child due to Chlamydia pneumoniae is reported. The diagnosis was made by the detection of chlamydial antigen in the tracheal secretion and a significant increase in C. pneumoniae antibody titre. The infection responded well to erythromycin therapy.
A study to determine the sensitivity and specificity of the Directogen Group A Streptococcal Test was carried out in a primary care clinic in University Hospital, Kuala Lumpur. The study also looked at the prevalence of streptococcal pharyngitis in the clinic. We found that the rapid test has a sensitivity of 90.9% and a specificity of 90.7%. Viral pharyngitis is the commonest form (63%) of pharyngitis followed by Group A Beta haemolytic streptococcal pharyngitis (14.2%). The presence of exudates, tonsillar enlargement and the presence of tender cervical lymph nodes have a significantly higher association with streptococcal pharyngitis.
Study site: Primary care clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
The seroprevalence of various Orientia tsutsugamushi (OT) strains among Malaysian patients with suspected scrub typhus infections was determined using an indirect immunoperoxidase (IIP) assay. IgG against a single OT strain were detected in six sera (3 Karp, 1 Gilliam and 2 TC586), whereas IgM antibodies against a single OT strain (Gilliam) were noted in 3 sera (Gilliam). IgG reactive to all OT strains were present in 33 (47.1%) of the 70 sera and IgM reactive to all OT strains were present in 22 (78.6%) of the 28 sera. The fact that most sera were reactive to multiple OT strains suggests that group-specific antigens are involved in scrub typhus infections, whereas very few were due to strain-specific epitopes present on these strains. Peak IgG and IgM titers were noted more frequently against Gilliam, Karp, and TA763 strains: this suggests that these strains may be the commonest infecting strains among Malaysian patients. Two predominant OT polypeptides consistently reacted with patients' sera were the 70 kDa and 56 kDa proteins.
Although well established in the West, stool antigen tests (SAT) are not widely used in Asia. Data on the accuracy of this test in Asia is sparse and, to date, there have been no studies looking at the more refined monoclonal SAT. The aim of this study is to validate the diagnostic accuracy of a stool antigen test, Hp STAR, for the detection of Helicobacter pylori.
To determine the prevalence of Helicobacter pylori antigen carriage in stool in the Penan ethnic minority in Malaysian Borneo, we studied 295 Penans 0.6-89.0 years of age from 1) the remote Limbang Division, 2) Mulu regional center, and 3) Belaga village. Overall, 37.7% of the subjects tested positive. Peak prevalence was reached by 10 years of age. There were no differences in age, sex, body mass index, and socioeconomic/domestic variables between antigen-positive and antigen-negative subjects. In a logistic regression analysis, subjects from Limbang were least likely to be antigen-positive (odds ratio [OR] = 0.23, 95% confidence interval [CI] = 0.12-0.44 versus other sites, P < 0.001). Availability of a flushing toilet was protective against H. pylori carriage (OR = 0.51, 95% CI = 0.27-0.95, P = 0.031). Infection with H. pylori among the Penan was less than reported in other low socioeconomic groups. The lowest prevalence in the most remote setting suggests that the infection has been a recent arrival in previously isolated communities.