Usefulness of a latex agglutination assay for FDP D-dimer to demonstrate the presence of postmortem blood

D-dimer, a specific fragment resulting from degradation of cross-linked fibrin, is an essential marker for the diagnosis of disseminated intravascular coagulation (DIC). Rapid assay for D-dimer using monoclonal antibody coated-latex particles might be useful for discriminating between postmortem and antemortem blood in bloodstains. We tried to detect D-dimer in nine postmortem blood samples by the rapid latex agglutination assay and to quantify them automatically using the latex photometric immunoassay system. The results showed that all samples were positive and that their amounts of D-dimer were 335-2,800 microg/ml (the normal blood level, <1 microg/ml; the pathogenic blood level with DIC, 1-100 microg/ml). Next, nine stains made of postmortem blood were examined by the rapid latex agglutination assay. The result showed that only one case (D-dimer 335 microg/ml blood) showed weak positive while the others (D-dimer 600-2,800 microg/ml blood) were positive. The present study indicates that the latex agglutination assay for D-dimer can be useful to demonstrate the presence of postmortem blood.

Leptospiral pneumonia

Severe leptospirosis rarely presents with primary pulmonary manifestations, without any associated jaundice or renal dysfunction. The authors report a nine-year-old boy who presented with complaints of abrupt onset of high fever; with myalgia, headache, and pain in right chest region, productive cough with hemoptysis and vomiting developing over the past 72 hours. Chest radiograph showed consolidation in the right upper lobe with air bronchogram. A history of contact with sewage water and presence of conjunctival suffusion in a child with pneumonia made us suspect leptospirosis. Following prompt initiation of parenteral penicillin therapy the child's complaints resolved over the next five days. Dri-Dot test to detect anti-Leptospira antibodies was positive. The diagnosis of leptospirosis was confirmed by a positive microagglutination test to Leptospira interrogans serovar Australis by a fourfold rise in antibody titer in paired sera collected during convalescence. Leptospirosis presenting with pulmonary hemorrhage has been associated with significant mortality but it can be successfully treated with early clinical suspicion of alveolar hemorrhage and prompt therapy.

Detection of antibodies to opioid and glutamate receptors by latex agglutination and enzyme immunoassay

We studied adsorption capacity of 5 latexes to synthetic peptide fragments of mu- and delta-opioid receptors and to GluR1 and NR2A subunits of glutamate receptor. Levels of autoantibodies to opioid receptors in the latex agglutination test and enzyme immunoassay were in good correlation. The level of autoantibodies to opioid receptors measured by these methods was increased in patients with opium narcomania, while the content of autoantibodies to the glutamate receptor subunits was increased in epileptics.

The prognostic and diagnostic markers of invasive candidiasis in patients during chemotherapy

The aim of the work was the early detection of Candida spp. in clinical samples of patients with carcinoma ovariorum undergoing chemotherapy by comparing three indicators of candidiasis: presence of mannan and yeast DNA in the bloodstream and colonization of mucosal membranes by Candida species as a prognostic marker of deep candidiasis. Thirty-one women with carcinoma ovariorum, during chemotherapy without symptoms of deep fungal infections, were examined twice over a six-day period. C. albicans was the dominant organism isolated from mucosal membranes. Two serum samples were positive for mannan on the first day of examination. All these patients were previously colonized by Candida spp. on mucous membranes. Four patients were positive on the last day of examination. Three of these patients were colonized by Candida spp. C. albicans infection was detected early in 4 out of 12 clinical samples by a combination of PCR and mannan-detecting methods. Colonization increases the risk of deep candidiasis. PCR and antigen detection are fast and reliable methods for early detection of Candida in bloodstream. For patients at risk, the clinical samples must be tested by at least two independent methods.

Serotypes of 286 group B streptococci isolated from asymptomatic carriers and invasive disease cases in Mexico

BACKGROUND

Group B Streptococcus (GBS) remains as a leading cause of neonatal sepsis and meningitis in developed countries, where type III is the most common serotype. Although GBS is considered an uncommon cause of perinatal pathology in Mexico, a vaginal colonization rate of 14% in pregnant women and a neonatal infection rate of 1/1500 live births have been reported. The aim of this study was to determine the serotype distribution in a collection of 286 GBS strains isolated in Mexico from asymptomatic carriers and in adult and neonatal invasive disease cases.

METHODS

The collection included GBS strains isolated between January 1988 and April 1998 at the Instituto Nacional de Perinatologia and Hospital de Pediatria in Mexico City. GBS and serotype were confirmed by latex agglutination.

RESULTS

Most strains were isolated from asymptomatic carriers (66%). 30% were invasive isolates, and 10% of them were from neonates. 48.6% were type I, 32.9% type III, 14% type II, and 4% were non-typeable.

CONCLUSION

Serotype I is predominant in Mexico but participation of serotype III is increasing, and a decrease of non-typeable isolates was detected.

Latex agglutination for bacterial antigens and meningococcus PCR: two useful tools in legal sudden deaths

Bacterial infections are considered to be a major cause of sudden deaths. The recognition of infections caused by Neisseria meningitidis is an essential duty of medicolegal offices due to the risk of secondary cases. Since other microorganisms, such as Haemophilus influenzae and Streptococcus pneumoniae, are also involved in infectious sudden deaths, the identification of the pathogen responsible for death is essential in order to establish a positive diagnosis while also preventing secondary meningococcal cases. However, because of the unreliability of culture methods used for autopsy specimens and the fragile nature of the microorganisms, other techniques were used. In this study, the detection of specific antigens of N. meningitidis (serogroups A, B, C, Y and W135), H. influenzae type b, S. pneumoniae and Group B Streptococcus was undertaken in 40 samples from sudden death cases in legal procedures with a latex agglutination test. In addition, a meningococcus polymerase chain reaction (PCR) assay (ctrA, crgA and siaD genes) was also used as a corroboration method for positive N. meningitidis agglutinations. Eleven cases of sudden death were confirmed to be due to meningococcus while one case was confirmed to have been caused by H. influenzae type b fulminant epiglottitis. Rapid laboratory diagnosis of meningococcal infection allowed contacts management and notification to the health authorities. From the point of view of the authors, forensic diagnosis of unascertained deaths should include latex agglutination and meningococcus PCR when a fulminant infection by N. meningitidis or H. influenzae is suspected as well as in deaths where the cause is unclear.

[Meningococcal disease diagnostic criteria in Greater Metropolitan Campinas, São Paulo State, Brazil]

The aim of this article is to evaluate confirmatory criteria: culture, latex agglutination, counter immunoelectrophoresis, microscopic examination, and clinical/epidemiological criteria for cases of meningococcal disease reported in Greater Metropolitan Campinas, São Paulo State, Brazil, from 1993 to 2002 (568 cases). The following variables were also studied: clinical features, gender, age, city, hospital, case fatality, seasonality, and Neisseria meningitidis serogroup. Culture as a confirmatory criterion was the dependent variable in univariate analysis. The mean proportion of confirmatory criterion by culture was 68.7%. Clinical features of meningococcal disease -- meningitis without septicemia (OR = 2.87; CI: 1.89-4.38) and septicemia without meningitis (OR = 0.26; CI: 0.17-0.45) -- were associated with confirmation by culture. Case fatality rates were different among all diagnostic criteria. More attention should be given to etiological diagnostic confirmation in more severe cases. Diagnostic methods such as PCR may improve etiological confirmation of meningococcal disease in cases with negative cultures.

Evaluation of polymerase chain reaction, conventional and MRSA screen latex agglutination methods for detection of methicillin-resistant, -borderline and -susceptible Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA), is difficult and expensive to treat, therefore early screening is essential. Several phenotypic and genotypic methods are used to detect MRSA; however, the method of choice remains problematic. We have evaluated four phenotypic methods, broth microdilution (MIC), oxacillin disk agar diffusion (ODD), oxacillin screening salt agar (OSS), and a new rapid phenotypic (MRSA screen latex agglutination, MSLA) with the genotypic gold standard of PCR mecA detection to determine the most appropriate method for routine laboratory use. We randomly collected 203 S. aureus isolates from patients and carriers at two hospitals in Thailand. Using MIC method, three sub-groups were differentiated from among these isolates, namely MRSA (106 isolates), borderline-resistant S. aureus (BRSA) (65 isolates), and methicillin-susceptible S. aureus (MSSA)(32 isolates). A total of 10 methicillin-resistant S. epidermidis (MRSE) isolates were also included. The sensitivity and specificity of MIC, ODD, OSS, and MSLA were 99 and 96, 100 and 97, 100 and 97, and 100 and 100%, respectively. Our study indicated that ODD is still appropriate for routine laboratory. MSLA had the highest sensitivity and specificity and is rapid but expensive, so is the most appropriate method for emergency cases. MIC method was better for BRSA detection and OSS method was more appropriate for screening clinical specimens and carriers.

A prospective evaluation of four immunodiagnotic assays for human leptospirosis

This was a prospective evaluation of four immunodiagnostic assays for human leptospirosis, including the indirect immunofluorescence test (IFA), the microscopic agglutination test (MAT), the LEPTO dipstick, and the latex agglutination (LA) test. Four hundred ninety-two serum samples were collected from 348 patients who presented with acute fever without localizing signs. The sensitivities of the IFA, MAT, Dipstick, and LA were 91.9, 76.6, 77.4, and 83.1%, respectively. The specificities of these assays were 100.0, 100.0, 89.3, and 83.5, respectively. Even though IFA showed the highest overall sensitivity and specificity, when acute sera were considered, the LA was the most sensitive (28.7%). All 3 genus specific antibody assays had broad reactivity against various serogroups. The MAT is best suited for the reference laboratory, where it can be maintained with the battery of live antigens; the IFA is suited for a laboratory with sophisticated equipment and technical expertise; the Dipstick and LA are suitable for peripheral laboratories which lack expensive equipment and expertise.

Staphylococcal enterotoxin-B-mediated stimulation of interleukin-13 production as a potential aetiologic factor in eczema in infants

BACKGROUND

Staphylococcus aureus colonization has been found in 80-100% of lesional skin from patients with atopic eczema dermatitis syndrome (AEDS) and is thought to have a role in the pathogenesis of the disease. Furthermore, up to 65% of S. aureus from lesional skin has been shown to produce toxigenic superantigens.

METHODS

Using a cohort of 11 children under 2 years of age diagnosed with AEDS, we isolated peripheral blood mononuclear cells, cultured them with staphylococcal enterotoxin B (SEB) and phytohaemagglutinin, and assessed the cytokine response profiles. Plasma was also collected for immunoglobulin E analysis. In addition, skin and nasal swabs were taken and cultured to determine the presence of SEB-producing S. aureus by polymerase chain reaction (PCR) and reverse passive latex agglutination.

RESULTS

We found a significant increase in the production of the SEB-induced cytokines interleukin (IL)-5 and IL-13 in the patient group when compared with non-atopic, healthy controls. For IL-13, there was almost no overlap in the levels between the groups. However, there was no correlation between SEB-induced IL-13 and disease severity. This difference was not seen when heat-inactivated S. aureus was used to stimulate the cells.

CONCLUSIONS

IL-13 is an important factor in AEDS development in early childhood, and prophylactic anti-staphylococcal treatment may provide protection from AEDS in atopic individuals.

Pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) has been recognized for almost half a century. At least three separate pathophysiologic mechanisms may lead to the characteristic feature of PAP: the excessive accumulation of surfactant lipoprotein in pulmonary alveoli, with associated disturbance of pulmonary gas exchange. The prognosis for adult patients with PAP varies, but disease-specific survival rate exceeds 80% at 5 years. The survival rates for adult PAP patients seem to have increased progressively in the four decades since the initial clinical description of this condition. The last decade has brought new advances in laboratory and clinical research that are lifting a veil not only on PAP but also on general aspects of pulmonary surfactant biology and innate immune defense.

Vaginal–Perianal Compared With Vaginal–Rectal Cultures for Identification of Group B Streptococci

OBJECTIVE

To estimate whether the rates of recovery of group B streptococci from combined vaginal and perianal cultures and combined vaginal and rectal cultures are equivalent.

METHODS

We performed a prospective cohort study of vaginal-perianal versus vaginal-rectal culture for group B streptococci. Two hundred pregnant women in the third trimester were enrolled. Three specimens were collected from each patient in the following order: lower third of the vagina, perianal skin, and rectum. Each specimen was cultured serially in selective broth media, then on sheep's blood agar. Suspicious colonies were confirmed by latex agglutination. Culture positivity rates from the combined sites of vagina and perianal skin were compared with vagina and rectum. Laboratory personnel were blinded to the collection site of each individual swab.

RESULTS

Of the 200 subjects, 71 (36%) had a positive culture from at least 1 site. Vaginal culture was positive in 55 patients (28%), compared with 48 patients (24%) with positive perianal cultures and 50 patients (25%) with positive rectal cultures. Results of combined vaginal and perianal cultures were positive in 68 patients (34%); results of combined vaginal and rectal cultures were positive in 67 patients (34%) (P = 1.0).

CONCLUSION

The group B streptococci detection rate from vaginal-perianal specimens is not significantly different from the detection rate from vaginal-rectal specimens. Therefore, pregnant women do not need to be subjected to the discomfort of collection of a rectal specimen.

LEVEL OF EVIDENCE

II-2.

Prevalence of Candida albicans and Trichomonas vaginalis in pregnant women in Havana City by an immunologic latex agglutination test

We aimed to estimate the prevalence of Candida albicans and Trichomonas vaginalis in immunocompetent pregnant women living in Havana City, Cuba, with or without symptoms of vaginitis, using a sample of 640 women from 6 Gyneco-obstetrics hospitals, which represents 2.5% of total yearly pregnant women. Diagnosis was made using a new latex agglutination kit (Newvagin C-Kure, La Habana, Cuba). Clinical sensitivity and specificity of this assay were validated against culture method, with 467 and 489 clinical specimens for Candida albicans and Trichomonas vaginalis, respectively. Results showed that the kit clinical sensitivity was 100% for Candida albicans and 86.7% for Trichomonas vaginalis compared with a clinical specificity of 93.3% for Candida albicans and 95.1% for Trichomonas vaginalis by culture. The prevalence of candidiasis was determined to be 42.3% (95% confidence interval [CI] 3.8%); the prevalence of trichomoniasis was 9.84% (95% CI 2.3%). In our sample, 48.7% of the women tested negative with respect to both candidiasis and trichomoniasis. Only 6.41% of the cases yielded inconclusive results. The test has high sensitivity, and our results indicate a relatively high prevalence of both infections. However, a significant difference (P < .001) was also observed in candidiasis and trichomoniasis prevalence among hospitals corresponding to the quantity of women with clinical vaginitis. No difference was observed between diabetics and nondiabetics, probably due to the special care of diabetic pregnant women. We conclude that the method is useful for this kind of vaginitis prevalence study and that candidiasis and trichomoniasis prevalences in pregnant women of Havana are 38.5% to 46.2 % (95% CI) and 7.5% to 12.1% (95% CI), respectively.

Toxoplasma gondii infection in animal-friendly pig production systems

PURPOSE

Consumption of undercooked pork meat products has been considered a major risk factor for contracting toxoplasmosis in humans. Indoor farming and improved hygiene have drastically reduced Toxoplasma infections in pigs over the past decades. Whether introduction of animal-friendly production systems will lead to a reemergence of Toxoplasma infections in pigs is not yet known. Investigating this possibility was the purpose of this study.

METHODS

Blood was obtained from pigs raised for slaughter and tested for Toxoplasma antibodies by using latex agglutination and indirect immunofluorescence testing, with confirmation by immunoblotting.

RESULTS

None of the slaughter pigs (n = 621) from conventional farms (n = 30) were positive, whereas 38 (2.9%) of 1295 animals from animal-friendly systems tested positive (n = 33 farms; 13 [39%] farms positive).

CONCLUSIONS

The following conclusions may be derived from this study: Conventionally (indoors) raised pigs are free from Toxoplasma infection, and (2) animal-friendly production systems may lead to a reemergence of Toxoplasma infections, although many of these farms remain Toxoplasma free. Slaughterhouse monitoring of pigs from animal-friendly production systems combined with on-farm prevention strategies should be applied to ensure safety for consumers of the meat products obtained from these animals.

High prevalence of enterohemorrhagic Escherichia coli (EHEC) O157 from cattle in selected regions of Japan

The prevalence of enterohemorrhagic Escherichia coli (EHEC) O157 was examined in bovine faeces. EHEC O157 was isolated from the faeces of 42 (13.0%) of 324 cattle. Of the 4 farms and the facilities tested, the 3 farms and the facilities were found positive for EHEC O157. The highest isolation rate among the farms was 33.7%. The prevalence of EHEC O157 in heifers was higher than that in calves and other cattle. No cattle positive for EHEC O157 showed any clinical signs except 2 calves with diarrhea in a veterinary hospital. Almost all isolates possessed the stx gene, and Stx-positive strains carrying both stx(1) and stx(2) genes were predominant. These results indicate that EHEC O157 are distributed in bovine faeces, and that dairy and beef farms in selected regions of Japan are heavily contaminated with the organisms.

Cryptococcal meningitis in two apparently immunocompetent Maltese patients

Two cases of cryptococcal meningitis occurring in immunocompetent men are described. The first case involves a farmer in whom cryptococcal meningitis was rapidly diagnosed using direct microscopy, latex antigen tests and culture of cerebrospinal fluid (CSF). In the second case, initial mycological tests on CSF (direct microscopy and culture) were repetitively negative and latex antigen tests gave unconvincing results. The patient was started on triple antituberculosis therapy, on which he improved immediately; therapy was continued for 1 year with the patient remaining well. However, within 1 week of stopping therapy, he had to be readmitted with neurological signs and symptoms. Culture of CSF this time yielded Cryptococcus neoformans and the antigen test was consistently positive. These are the first reported cases of cryptococcal meningitis in immunocompetent patients in Malta.

Methicillin resistance of staphylococci isolated from the skin of dogs with pyoderma

OBJECTIVE

To determine the methicillin-resistant profile of staphylococcal isolates from the skin of dogs with pyoderma.

ANIMALS

90 dogs with pyoderma.

PROCEDURE

Staphylococci isolated from dogs with pyoderma were tested for susceptibility to methicillin by use of a standard disk diffusion test with oxacillin disks. The DNA extracted from the isolates was tested for the mecA gene that encodes the penicillin-binding protein 2a (PBP2a) by use of a polymerase chain reaction (PCR) assay. The expression of PBP2a was determined with a commercial latex agglutination assay. Species of staphylococcal isolates were identified by use of morphologic, biochemical, and enzymatic tests.

RESULTS

Most of the isolated staphylococci were methicillin-susceptible, coagulase-positive Staphylococcus intermedius isolates. Whereas only 2 of 57 S. intermedius isolates were resistant to methicillin, approximately half of the isolates had the mecA gene and produced PBP2a. Staphylococcus schleiferi was the second most common isolate. Widespread resistance to methicillin was found among S. schleiferi isolates. More coagulase-negative S. schleiferi isolates were identified with mecA gene-mediated resistance to methicillin, compared with coagulase-positive S. schleiferi isolates.

CONCLUSIONS AND CLINICAL RELEVANCE

The latex agglutination assay for the detection of PBP2a expression coupled with the PCR assay for the mecA gene may provide new information about emerging antimicrobial resistance among staphylococcal isolates.

[Detection of antibiotic contents in cerebrospinal fluid]

The suggested method provides for the semi-quantitative detection of antibiotics in liquor made for the purpose of prognosticating the possibility of cultural secretion of infectious agents of purulent bacterial meningitis (PBM); it is also a basis for the need in using the non-cultural diagnostic tools. The method can be used in detecting the pharmacokinetic specificity of antibacterial drugs now in use and of their combinations with the aim of making corrections in antibiotic therapy. It is based on inhibiting the surface growth of test-culture by a liquor-dissolved antibiotic with the growth-delay zone being shaped. The preparation concentration is estimated in U/ml of the penicillin equivalent (PE). Examinations of 131 liquor samples (primary puncture) obtained from patients with meningitis showed clear-cut correlations between the antibiotics' concentrations, cultural verification of the PBM diagnosis and the efficiency of non-cultural examinations. 82.14% of cultures were derived from liquor samples with the negative antibacterial activity (range 1); 7.14% of cultures were derived from liquor samples containing the antibacterial preparation of up to 0.5 U/ml PE (range 2); culture of secondary PBM agents (S. aureus) were isolated from liquor samples containing up to 10 U/ml PE (range 3); and no microbe agents were isolated from liquor samples containing above 10 U/ml PE (range 4). The designed method, when used, demonstrated a high efficiency and significance of laboratory PBM diagnosis in presence of the antibacterial liquor efficiency.

Hematologic differences in heterophile-positive and heterophile-negative infectious mononucleosis

Infectious mononucleosis (IM) due to all causes is characterized by atypical lymphocytosis. We sought to compare hematologic parameters of infectious mononucleosis due to Epstein-Barr virus (EBV) infection (heterophile antibody (HA) positive) with mononucleosis due to other causes. Mono-Latex Slide Agglutination Test results and complete blood counts (CBC) of 147 patients with mononucleosis were retrospectively analyzed. Leukocyte count, absolute lymphocyte count, and presence of atypical lymphocytes in EBV-positive and EBV-negative groups were statistically compared. We analyzed 68 EBV-positive and 79 EBV-negative cases. EBV-positive patients were significantly younger than EBV-negative patients were. Mean total WBC count and mean absolute lymphocyte count were significantly higher in EBV-positive patients. Absolute lymphocytosis, absolute leukocytosis, and atypical lymphocytosis were also significantly more frequent in EBV-positive patients. Leukopenia was more frequently seen in EBV-negative patients.

Cerebrospinal latex agglutination fails to contribute to the microbiologic diagnosis of pretreated children with meningitis

We conducted a 10-year retrospective study of all children who had cerebrospinal fluid latex agglutination testing for bacterial antigens performed at 1 tertiary care urban children's hospital. Of the 176 patients with culture-negative meningitis who were pretreated with antibiotics before lumbar puncture, none had a positive latex agglutination study (0 of 176; 95% confidence interval, 0-2%). Latex agglutination studies identified no additional cases of bacterial meningitis beyond those identified by culture in pretreated patients. Clinical decision-making algorithms for the management of pretreated patients at risk for bacterial meningitis should not include latex agglutination testing.

Immunoreactivity of cryptococcal antigen is not stable under prolonged incubations in human serum

The stability of cryptococcal antigen from Cryptococcus neoformans serotype A and D strains at different temperatures in serum and other solvents was studied. Samples stored at -20 or 4 degrees C had equivalent stabilities as measured by the Premier Cryptococcal Antigen kit and the Cryptococcal Antigen Latex Agglutination System (CALAS) kit. However, using the Premier Cryptococcal Antigen kit, there was a 91% loss of reactivity in samples incubated in human serum for 4 weeks at 37 degrees C. A loss of reactivity of more than 99% was observed after incubation at 45 degrees C for 4 weeks. The capsular antigen was not detected by the Premier Cryptococcal Antigen kit after 16 weeks at elevated temperatures. Antigen titers were also reduced in a latex agglutination assay (CALAS) after 4 weeks at 37 and 45 degrees C. The loss of antigen reactivity was a function of pH and temperature.

Occurrence and clonal relatedness of sec/tst-gene positive Staphylococcus aureus isolates of quartermilk samples of cows suffering from mastitis

AIMS

To investigate the prevalence of sec/tst-gene positive Staphylococcus aureus in bovine mastitis and to get information about the clonal relatedness of these clinical isolates.

METHODS AND RESULTS

A total of 533 Staph. aureus strains isolated from bovine mastitic quartermilk samples at 493 randomized dairy farms in Hessia, Germany, from January 1997 until June 1998 were examined for enterotoxin C (sec) gene and toxic shock syndrome toxin (tst) gene by multiplex polymerase chain reaction. Fifty-three (9.3%) of the strains were sec/tst-gene positive. Phenotypic TSST-1 production was found in all positive strains by reversed passive latex agglutination test. With DNA macrorestriction analysis, sec/tst-gene positive strains were divided into five different macrorestriction types. Type I (10 isolates) and III (40 isolates) were found to be the predominant types in terms of frequency of isolation in the investigated area. These DNA macrorestriction types differed in only two bands in the 500 and 270 bp region.

CONCLUSIONS

Closely related Staph. aureus strains seem to be responsible for an unusual large proportion of bovine mastitis cases in geographically widely distinct locations.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is one of the first reports about the relatedness of sec/tst-gene positive Staph. aureus clinical isolates from bovine mastitis.

Latex agglutination test for ferritin measurement

Ferritin is an indispensable parameter in the diagnosis of latent iron deficiency anemia or siderosis. In this study, we evaluated the utility of a reagent for ferritin measurement in a latex agglutination (LA) test, using general chemistry analyzers. The intraassay coefficient of variation (CV) was 0.8-3.4% and the interassay CV was 0.0-0.7%. Linearity was observed up to 1100 ng/mL. The effective sensitivity value was 4.0 ng/mL. In addition, good results were obtained with the prozone test, the effects of interferences, correlation with the enzyme immunoassay (EIA) method, and functional assay sensitivity. A significant positive correlation with C-reactive protein (r=0.586, P<0.001) was found. When compared with liver-related biochemical parameters (asparate aminotransferase (AST) and alanine aminotransferase (ALT)) in patients with impaired liver function, ferritin varied in parallel with the liver-related parameters. This assay system was able to measure ferritin accurately over a wide range, and thus could be used to diagnose cancer, siderosis, and iron deficiency anemia. The LA assay system can be employed for measurement with general chemistry analyzers, with rapid and convenient execution. In addition, the LA test allows the simultaneous measurement of other markers of iron deficiency anemia, so clinicians can rapidly obtain examination results.

Rotavirus RNA electropherotype in different states in Malaysia for the year 2000 and 2001

A total of 157 stool samples were examined for Group A rotaviruses in diarrheic children admitted to 8 different major hospitals in Malaysia. The overall incidence rate in this study was 19.7% (31 of 157) with a variation of 9.5% to 39.1% in different locations. Majority of the infections detected were in those under 2 years of age and there were fewer admissions in the older age group. The stool samples were initially screened for rotavirus Group A by latex agglutination method and followed by RNA electrophoresis. The size and the characteristics wheel-shaped morphology of the viral preparations when examined by electron-microscopy further confirmed the presence of rotaviruses in the positive stool samples. Analysis of the RNA pattern showed that majority of the isolates, 51.6% (16 of 31) were Type IIC ('long' with comigration of RNA segments 7 and 8), 35.5% (11 of 31) with Type IIG ('long' with comigration of segments 7, 8, 9), 9.7% (3 of 31) with Type IG ('short' with comigration of RNA segments 7, 8, 9) and 3.2% (1 of 31) of mixed or atypical pattern. It appeared that over a 12 year interval, only one new or unusual rotavirus electropherotype was found. This is the first comprehensive report on the electropherotypes of rotaviruses covering eight different geographical locations in Malaysia and the data obtained is useful for understanding the geographic distribution and types of rotaviruses transmitting in Malaysia.

Occurrence of Shiga toxin-producing Escherichia coli O157 in selected dairy and meat products marketed in the city of Rabat, Morocco

Samples of meat and dairy products taken from the city of Rabat, Morocco, were examined for the presence of Escherichia coli O157 by the selective enrichment procedure followed by plating on cefixime-tellurite-sorbitol MacConkey agar and a latex agglutination test. The ability of isolates to produce Shiga toxins (ST1 or ST2) was also tested by an agglutination test using sensitized latex. Dairy samples (n = 44) included different products commonly consumed in the country. Meat samples (n = 36) were taken from traditional butchers because these products are generally marketed in this way. Random samples were taken from each product during the period of January through May. Of the 80 samples tested, 8 (10%) harbored E. coli O157. Four dairy and four meat samples were contaminated (9.1 and 11.1%, respectively). Of 10 E. coli O157 isolates from contaminated samples demonstrating true antigen-antibody agglutination, 5 (50%) produced either ST2 alone or ST2 plus ST1. Four of the five strains (80%) were meat isolates and produced ST2 with or without ST1, and the fifth was a dairy isolate producing ST2.

Evaluation of the methicillin-resistant Staphylococcus aureus (MRSA)-Screen latex agglutination test for detection of MRSA of animal origin

Methicillin (oxacillin)-resistant staphylococci (MRS) have emerged as major clinical and epidemiological pathogens, and there have been frequent reports of MRS infections in the veterinary field. The MRSA-Screen latex agglutination test (Denka Seiken Co., Ltd., Tokyo, Japan) was compared with an oxacillin agar screen test, MIC determination, and mecA PCR assay, the "gold standard." In an analysis of 15 mecA-positive and 48 mecA-negative S. aureus animal isolates, as well as 9 mecA-positive and 147 mecA-negative, coagulase-negative staphylococcal animal isolates, the latex agglutination test surpassed the widely used oxacillin agar screen method and MIC determination, with a sensitivity and a specificity of 100%. The MRSA-Screen test is a reliable and rapid method of detecting MRS in the veterinary field.

Rotavirus infection in children with acute diarrhea as detected by latex agglutination, ELISA and polyacrylamide gel electrophoresis

We examined prospectively, stool specimens from 135 children, 0 to 3 years old, referred for fever, abdominal pain, vomiting and/or acute diarrhea. Rotavirus antigens were detected from fecal samples by latex agglutination (LA), ELISA and polyacrylamide gel electrophoresis (PAGE). Rotavirus antigen positivity by Latex, ELISA and PAGE were 15, 55%, 12.59% and 11.85%, respectively. With PAGE test as reference, the sensitivity and specificity of LA and ELISA tests was 93.75%, 94.96% and 100%, 99.16%, respectively, The positivity ratio between 13-24 months group was meaningful with all tests (P = 0.042 for LA; P = 0.05 for ELISA; P = 0.031 for PAGE). ELISA and LA use found to be as sensitive and specific as PAGE in the diagnosis of rotavirus diarrhea.

Prevalence of anti-Toxoplasma gondii antibody in hunter-killed wild boars, Sus scrofa leucomystax, on Amakusa Island, Kumamoto Prefecture, Japan

The prevalence of Toxoplasma gondii was surveyed in wild boars (Sus scrofa leucomystax) and domiciled cats obtained in various areas of Amakusa Island, Kumamoto Prefecture, Japan. The antibody titers against T. gondii were measured with a latex agglutination test. Among specimens taken from 90 wild boars, 1 (1.1%) was positive and 3 (3.3%)were doubtfully positive. Among the specimens from 50 cats, none were positive and 1 (3.3%) was doubtfully positive. These results suggest that the wild boars and cats on Amakusa Island have quite low prevalence of the T. gondii infection. Continuous surveys will be needed to monitor the prevalence of Toxoplasmosis and other zoonoses in game animals.

Lipopolysaccharide O-Antigen Antibody-Based Detection of the Fish Pathogen Flavobacterium psychrophilum

Several yellow-pigmented species within the family Flavobacteriaceae are commonly associated with diseases in fish and are difficult to speciate due to their fastidious, slow-growing nature and cross-reactive antigens. Here we report the development of specific, antibody-diagnostic tests for Flavobacterium psychrophilum, the aetiological agent of rainbow trout fry syndrome and bacterial cold water disease. A unique antigen from F. psychrophilum, the lipopolysaccharide (LPS) O-polysaccharide (O-PS), formed the basis for the antibody test. LPS O-PS was purified and conjugated to keyhole limpet haemocyanin and bovine serum albumin for the generation of rabbit immune sera and the development of antibody-based diagnostic tests. Rabbit polyclonal anti-O-PS serum was highly specific for F. psychrophilum, without the need for prior cross-absorption with related bacteria and was the basis of an effective ELISA diagnostic test. Antibodies were purified from rabbit anti-O-PS serum and adsorbed onto coloured latex beads for the development of a specific, bead agglutination assay for F. psychrophilum.

Serological methods and selective agars to enumerate Campylobacter from broiler carcasses: data from inter- and intralaboratory analyses

Routine analytical means to estimate Campylobacter numbers per milliliter of carcass rinses are needed in high-sample-throughput poultry laboratories. We compared three serological confirmatory tests that were amenable to such a setting when used in conjunction with Campy-Line and Campy-Cefex Campylobacter selective agars. Pre- and post-chlorinated chiller carcass rinse samples were obtained and held on ice, then analyzed 24 h later in two separate laboratories. Presumptive counts on both pre- and postchiller samples from between laboratories on individual agars and between both agars were highly correlated. Agreement among the three serological tests was nearly complete. The use of a premeasured and dried latex anti-Campylobacter antibody agglutination test format was superior to that of either a liquid latex agglutination format or a direct phosphate-buffer microscopic technique in terms of practicality as was the inclusion of an unarmed latex control to detect auto agglutination. A routine procedure for Campylobacter level estimation was suggested. This procedure, when used in conjunction with a serological confirmatory step, should provide processors with a means to assess reductions in numbers per milliliter of carcass rinses versus strictly presence-absence testing.

Development of a sandwich dot–enzyme linked immunosorbent assay for Streptococcus pneumoniae antigen detection in cerebrospinal fluid

A new sandwich dot-enzyme linked immunosorbent assay (sdot-ELISA) was developed using omniserum prepared against different strains of Streptococcus pneumoniae as capture antibody and also as second or revealing antibody after its conjugation with horseradish peroxidase (HRP) for detection of pneumococcal antigen in cerebrospinal fluid (CSF). A total of 103 CSF samples of different categories were screened with newly developed dot-ELISA and results were compared with commercially available latex agglutination (LA) kit. The newly developed sdot-ELISA was more sensitive than LA test and can be used as an alternative diagnostic tool in laboratory and in field conditions. An added advantage of this ELISA system was that it did not require antibodies produced in two different animal species.

[Faecal occult blood testing: comparison of a latex agglutination test (Hemolex) and an immunoturbidimetric test (QuikRead FOB)]

Occult blood detection is the most prescribed faecal examination.

AIM

To compare results obtained with the latex agglutination test Hémolex LA (Orion diagnostica, Finlande) with those given by an immuno-turbidimetric test which allows an automatic reading (QuikRead FOB, Orion diagnostica, Finlande).

MATERIAL AND METHODS

this prospective study was carried out in 140 patients. The reference method was the latex agglutination test, Hemolex LA performed on stool extract obtained through weighting samples. On the base of the results, samples were separated into 2 groups: positive (n = 45) and negative (n = 95). As the QuikRead FOB test indicated a stool extract obtained through a sampling set, such an extraction was performed before Hemolex LA et QuikRead FOB testing.

RESULTS

all the 95 samples from the negative group gave similar results with the 3 methods. In contrast, 12/45 of the positive samples gave conflicting results, 11 results were negative with the 2 tests performed on stool extract obtained via sampling set, 1 result was negative with the QuikRead FOB method only.

DISCUSSION

analytical performance were similar with the 2 methods and discrepancies observed wi-thin the positive group were mainly related to the extraction method.

A novel positive regulatory element for exfoliative toxin A gene expression in Staphylococcus aureus

A 1·4 kb positive regulatory element (ETAexp ) that controls staphylococcal exfoliative toxin A (sETA) transcription was cloned from Staphylococcus aureus. ETAexp is located upstream of the cloned 5·8 kb eta gene (etaJ1) obtained from the chomosomal DNA of S. aureus ZM, the standard ETA-producing strain. The cETA prepared from an Escherichia coli transformant into which the recombinant plasmid petaJ1 (5·8 kb eta/pUC9) had been introduced was expressed at high levels in the culture supernatant and the ammonium-sulfate-precipitated culture supernatant fraction as shown by immunoblotting and the single radial immunodiffusion test. However, cETA produced by the recombinant plasmid petaJ3 containing the 1·7 kb eta sequence (etaJ3) with a 1·45 kb ETAexp -deficient eta fragment (1·7 kb eta/pUC9) obtained from the 5·8 kb eta sequence by subcloning was not detected in either the culture supernatant or the ammonium-sulfate-precipitated culture supernatant fraction (167-fold concentrate of the culture supernatant) by immunoblotting or the single radial immunodiffusion test. A large amount of cETA was produced by the 1·7 kb eta sequence when it was linked to ETAexp amplified by PCR (1·7 kb eta-ETAexp /pUC9), regardless of the orientation of ETAexp insertion. Northern blot hybridization showed lower levels of the transcripts of the 1·7 kb eta sequence than of the 5·8 kb eta sequence. The rsETA prepared from an S. aureus transformant into which the recombinant plasmid 3·4 kb eta-ETAexp /pYT3 (pYT3-etaJ6) had been introduced was expressed at high levels in the culture supernatant fraction as shown by the latex agglutination test. However, the agglutination titre in the culture supernatant fraction of rsETA produced by the recombinant plasmid (1·7 kb eta/pYT3) containing the 1·7 kb eta sequence carrying the 1·4 kb ETAexp -deficient eta fragment (pYT3-etaJ3) was 2500–4000 times lower than that of pYT3-etaJ6.

D-dimers in the emergency department evaluation of aortic dissection

Aortic dissection (AD) is the most common acute aortic condition requiring urgent surgery. AD, if not diagnosed in the emergency department (ED), is frequently fatal. AD is a difficult antemortem diagnosis.

OBJECTIVES

To determine if acute AD is associated with an elevation of fibrin degradation products, D-dimers.

METHODS

This was a retrospective chart review of patients diagnosed as having AD in the ED in whom a D-dimer determination was obtained in the ED, prior to any therapeutic intervention. The study was conducted in an urban Level I trauma center between October 1996 and September 2000. Exclusion criteria were referred patients with known diagnosis of AD. The D-dimer assay used was the semiquantitative latex agglutination assay, with a normal range up to 0.5 micro g/mL.

RESULTS

One hundred fifty-six patients were diagnosed as having AD in the ED. Seven patients had a D-dimer assay during their workup. All seven had a positive test.

CONCLUSIONS

All seven patients with an AD who had D-dimer assays performed in the ED had positive results by latex agglutination.

Rapid immunochromatographic test using recombinant SAG2 for detection of antibodies against Toxoplasma gondii in cats

An immunochromatographic test using recombinant truncated surface antigen 2 for detection of antibodies against Toxoplasma gondii was developed. Evaluation of detection of the antibody in mice and cats suggests that this test is rapid, simple, accurate, relatively inexpensive, and suitable for use under field conditions.

Comparison of dio-bacit, bacitracin-trimethoprim/ sulphamethoxazole and latex agglutination in the diagnosis of Group A beta-hemolytic streptococci

Not only is Group A beta-hemolytic Streptococcus (GAS) the most frequent cause of bacterial pharyngitis, it is also the culprit in various skin and systemic infections, acute rheumatic fever, post streptococcal glomerulonephritis, and other disorders and complications. A new, ready-to-use media, Dio-Bacit, in a two section plate containing 5% sheep blood agar on one side and sheep blood agar with bacitracin (2 microg/ml) on the other was compared for its efficiency in identifying GAS with bacitracin and bacitracin + sulphamethaxazole / trimethoprim disk tests applied after isolation of beta-hemolytic colonies. We also used the latex-agglutination test as the gold standard method for differentiating GAS from streptococci belonging to other groups. Compared with the latex-agglutination test, we found the sensitivity and specificity of the Dio-Bacit method to be 92.0% and 96.9%, respectively. Dio-Bacit plates provide an easy and very useful way to identify GAS within one day, saving time, labor, and money for routine diagnostic microbiology laboratories.

Sensitivity and specificity of the semiquantitative latex agglutination D-dimer assay for the diagnosis of acute pulmonary embolism as defined by computed tomographic angiography

OBJECTIVE

To determine the sensitivity and specificity of the semiquantitative latex agglutination plasma fibrin D-dimer assay for the diagnosis of acute pulmonary embolism by using computed tomographic (CT) angiography as the diagnostic reference standard.

PATIENTS AND METHODS

From January 1, 1998, to June 26, 2000, patients who had both semiquantitative latex agglutination plasma fibrin D-dimer testing and CT angiography for suspected acute pulmonary embolism were selected for the study. A D-dimer value greater than 250 ng/mL was considered positive for thromboembolic disease. Diagnosis of acute pulmonary embolism was based solely on the interpretation of the CT angiogram. The D-dimer assay results were then compared with the CT angiographic diagnoses.

RESULTS

Of 946 CT studies, 172 (18%) were positive for acute pulmonary embolism. The D-dimer assay was positive for 612 (65%) of the 946 patients. For acute pulmonary embolism, the D-dimer assay had a sensitivity of 0.83 (95% confidence interval [CI], 0.76-0.88), a specificity of 039 (95% CI, 036-0.43), a negative likelihood ratio of 0.44 (95 % CI, 032-0.62), and a negative predictive value of 0.91 (95% CI, 0.87-0.94).

CONCLUSIONS

The semiquantitative latex agglutination plasma fibrin D-dimer assay had moderate sensitivity and low specificity for the diagnosis of acute pulmonary embolism. When used alone, the results of this test were insufficient to exclude this serious and potentially fatal disorder. Approximately two thirds of our patients had positive D-dimer assays and required further evaluation to exclude acute pulmonary embolism.

[Prospective study of rotaviral infections in children hospitalized at the Clinic of Pediatric Infectious Diseases in Białystok in 2003]

Rotavirus is the most common gastrointestinal pathogen in infants and young children. The aim of this study was to determine the role of rotavirus in acute diarrhea in children hospitalized in Pediatric Infectious Diseases Clinic in Bialystok. 658 children aged 0-7 years admitted to the ward: 466 children with gastroenteritis and another 192 without any diarrheic symptoms were tested for rotavirus infection by latex agglutination. Rotavirus was detected in 16.1% stool specimens collected from children with acute diarrhea. None of patients without diarrhea was positive for rotavirus on admission--2% of this patients acquired symptomatic rotavirus infection during hospitalization. This study delivers epidemiological data on rotavirus infection and shows the need of further study on etiology of viral gastroenteritis in children in our district.

[Design of an agglutination latex test to detect venoms from Viperidae snakes in patients' serum]

This latex agglutination test was designed as a tool in the diagnosis of the ophidic accidents The development of specific trials to identify venoms from the most common snakes inVenezuela in human sera, could contribute to the improvement of the diagnosis of these accidents caused by snakes of the Bothrops and Crotalus genera, and in the control of the antiophidic serum for the treatment in an adequate and immediate way. The results obtained revealed a sensitivity of 167 mg/mL with good specificity, rapidity (10 minutes) and simplicity, since it can be accomplished by personnel with a basic training and only a microscope is necessary. All these reasons show the potential of this technique. It is required to complement the results with studies of the different factors that take part in the making of the latex reagent and that allow to improve its quality. Among these modifications it is suggested to improve the detection of smaller quantities of venom, to prove the recognition of the specific immunoglobulin sensitized latex particles against the Bothrops and Crotalus venbm, and to reproduce the test at the clinical level by using serum from patients that have been victims of ophidic accidents.

[Methicillin resistance detection in Staphylococcus aureus: comparison between conventional methods and MRSA-Screen latex agglutination technique]

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen that has emerged over the last four decades, causing both nosocomial and community-acquired infections. Rapid and accurate detection of methicillin resistance in S. aureus is important for the use of appropriate antimicrobial therapy and for the control of nosocomial spread of MRSA strains. We evaluated the efficiency of conventional methods for detection of methicillin resistance such as the disk diffusion, agar dilution, oxacillin agar screen test, and the latex agglutination test MRSA-Screen latex, in 100 isolates of S. aureus, 79 mecA positive and 21 mecA negative. The MRSA-Screen latex (Denka Seiken, Niigata, Japón), is a latex agglutination method that detects the presence of PLP-2a, product of mecA gene in S. aureus. The PCR of the mecA gene was used as the "gold standard" for the evaluation of the different methods tested. The percentages of sensitivity and specificity were as follows: disk difusión 97 and 100%, agar dilution 97 and 95%, oxacillin agar screen test 100 and 100%, and MRSA-Screen latex, 100 and 100 %. All methods presented high sensitivity and specificity, but MRSA-Screen latex had the advantage of giving a reliable result, equivalent to PCR, in only 15 minutes.

Molecular Typing of Enterotoxigenic Staphylococcus aureus Isolated from Bovine Mastitis in Korea

One hundred and sixty-six Staphylococcus aureus isolates from mastitic milk samples from different cows on 26 farms were investigated for staphylococcal enterotoxins(SEs) and toxic shock syndrome toxin-1(TSST-1) by polymerase chain reaction(PCR) and reverse passive latex agglutination assay(RPLA). SEs and the TSST-1 gene were detected in thirty-seven isolates based on a multiplex PCR; SEA was detected in 32 isolates, SEB in 3 isolates, SEC in 1 isolate, and SEA and the TSST-1 gene in 1 isolate. Of the 37 enterotoxigenic isolates, thirty-three isolates were enterotoxigenic according to RPLA, where 29 isolates produced SEA, 3 isolates produced SEB, and 1 isolate produced SEC. The enterotoxin-producing S. aureus isolates were further characterized by pulsed-field gel electrophoresis(PFGE). A macrorestriction analysis revealed 11 PFGE patterns. Among the 33 enterotoxigenic S. aureus isolates, 45.4% exhibited the same PFGE pattern I. Accordingly, although the enterotoxin-producing S. aureus isolates from bovine mastitis were genetically diverse, 1 common genotype prevailed on the farms, indicating that PFGE pattern I isolates may be the most disseminated in Korea.

Assessment of three rapid methods for the detection of methicillin-resistant Staphylococcus aureus

We evaluated three rapid methods to detect methicillin-resistant Staphylococcus aureus (MRSA) and compared them with PCR amplification of mecA. A total of 103 S. aureus strains were studied by MRSA-Screen, BBL Crystal, Velogene Genomic and mecA PCR. All the methods detected the 61 MRSA strains having the mecA gene, showing 100% sensitivity and specificity. Despite the correlation between all the rapid methods and PCR, the ease of use and shorter turnaround time of MRSA-Screen were important factors leading to the selection of this method as the routine screening technique for MRSA.