Commercial Serological Tests Research Articles

Performance of Commercial Herpes Simplex Virus Type-2 Antibody Tests Using Serum Samples From Sub-Saharan Africa: A Systematic Review and Meta-analysis

Several commercial type-specific serologic tests are available for herpes simplex virus type 2 (HSV-2). Poor specificity of some tests has been reported on samples from sub-Saharan Africa. To summarize the performance of the tests using samples from sub-Saharan Africa, we conducted a systematic review of publications reporting performance of commercially available HSV-2 tests against a gold standard (Western Blot or monoclonal antibody-blocking EIA). We used random-effects meta-analyses to summarize sensitivity and specificity of the 2 most commonly evaluated tests, Kalon gG2 enzyme-linked immunosorbent assay (ELISA), and Focus HerpeSelect HSV-2 ELISA. We identified 10 eligible articles that included 21 studies of the performance of Focus, and 12 of Kalon. The primary analyses included studies using the manufacturers' cut-offs (index value = 1.1). Focus had high sensitivity (random effects summary estimate 99%, 95% confidence interval [CI]: 99%-100%) but low specificity (69%, 95% CI: 59%-80%). Kalon had sensitivity of 95% (95% CI: 93%-97%) and specificity of 91% (95% CI: 86%-95%). Specificity of Focus was significantly lower (P = 0.002) among HIV-positive (54%, 95% CI: 40%-68%) than HIV-negative individuals (69%, 95% CI: 56%-82%). When the cut-off optical density index was increased above the recommended value of 1.1 to between 2.2 and 3.5, the specificity of Focus increased to 85% (95% CI: 77%-92%). Sensitivity and specificity of HSV-2 tests used in sub-Saharan Africa vary by setting, and are lower than reported from studies in the United States and Europe. Increasing the cut-off optical density index may improve test performance. Evaluation of test performance in a given setting may help deciding which test is most appropriate.

Les leishmanioses viscérales méditerranéennes

Mediterranean visceral leishmaniasis is a parasitic zoonosis due to Leishmania infantum. The dog is the reservoir species and also the main victim. The vector is the female Phlebotomus sand fly. In the southern Mediterranean region the disease is most frequent in children, whereas in Europe, and particularly in France, it is mostly an opportunistic infection associated with immunosuppression. Frequent asymptomatic carriage has been detected in southern Europe. The classic symptom triad consists of fever, pallor and splenomegaly. Biological signs include low cell blood counts (anemia, leukoneutropenia, and thrombocytopenia) and an inflammatory syndrome. Commercial serologic tests such as those based on immunoblotting are very useful. The gold standard for diagnosis is parasite detection in bone marrow or blood. PCR is useful for therapeutic follow-up. Treatment is currently based on liposomal amphotericin B (AmBisome).

Commercial serological tests for the diagnosis of active tuberculosis in India: Time for introspection

India accounts for one fifth of the global TB burden – a total of 9.2 million new cases and 1.7 million deaths every year1,2. There are two main components of effective TB control programme: the rapid and sensitive diagnosis of the disease and containment of its spread to the uninfected population. The sputum smear microscopy, still a backbone of TB diagnosis, is less sensitive and can miss half of the pulmonary TB cases. The conventional culture method which uses egg based medium (Lowenstein-Jensen, L-J) is time consuming and lacks desirable detection level. Liquid automated culture methods, such as Bactec-MGIT (BD, USA) and MB-Bact (Biomerieux, France) have highly improved detection rates, comparatively much faster (median detection time 10-24 days) but are costly requiring air handling and infection control measures1. Molecular methods such as polymerase chain reaction (PCR) and its modified versions have come as boon in the diagnosis of tuberculosis. Despite the limitation of detecting dead bacilli, PCR is rapid (report can be made available on the same day) and precise, depending on the gene sequences targeted and protocols used. These methods can be used on various clinical samples such as sputum, tissue biopsies, cerebrospinal and other body fluids, lymph nodes and other tissue aspirates, urine, faeces, etc1. In resource limited settings like India, tuberculosis detection rates are suboptimal mainly because the diagnosis is usually made by less sensitive tools such as sputum microscopy and chest X-rays. The poor detection rates lead to mismanagement of infectious cases and possibility of drug resistance development. However, non-availability of affordable, rapid and precise diagnostic tools at peripheral level have led to mushrooming of commercial serological tests2–4. Extensive reviews and meta-analyses have concluded that the presently available antibody detection based serological tests are no good for the diagnosis of tuberculosis while helpful for other diseases. In view of this, the WHO has recently issued an advisory2. This editorial provides an academic overview of the issue.

Do Commercial Serologic Tests for Trypanosoma cruzi Infection Detect Mexican Strains in Women and Newborns?

We sought to determine the serological test that could be used for Trypanosoma cruzi seroprevalence studies in Mexico, where lineage I predominates. In a previous study among pregnant women and their newborns in the states of Yucatan and Guanajuato, we reported a 0.8-0.9% of prevalence for T. cruzi -specific antibodies by Stat-Pak and Wiener ELISA. We have expanded this study here by performing an additional non-commercial ELISA and confirming the seropositives with Western blot, using whole antigens of a local parasite strain. We found a seroprevalence of 0.6% (3/500) in Merida and 0.4% in Guanajuato (2/488). The 5 seropositive umbilical cord samples reacted to both non-commercial ELISA and Western blot tests, and only 1 of the maternal samples was not reactive to non-commercial ELISA. A follow-up of the newborns at 10 mo was performed in Yucatan to determine the presence of T. cruzi antibodies in children as evidence of congenital infection. None of the children was seropositive. One newborn from an infected mother died at 2 wk of age of cardiac arrest, but T. cruzi infection was not confirmed. The T. cruzi seroprevalence data obtained with both commercial tests (Stat-Pak and ELISA Wiener) are similar to those from non-commercial tests using a local Mexican strain of T. cruzi.

Comparison of five commercial serological tests for the detection of anti-Chlamydia trachomatis antibodies

Screening for Chlamydia trachomatis-specific antibodies is valuable in investigating recurrent miscarriage, tubal infertility and extrauterine pregnancy. We compared here the performance of immunofluorescence (IF) to four other commercial tests in detecting IgG antibodies directed against C. trachomatis: two enzyme-linked immunosorbent assays (ELISAs) using the major outer membrane protein (MOMP) as the antigen, commercialised respectively by Medac and R-Biopharm (RB), one ELISA using the chlamydial heat shock protein 60 (cHSP60) as the antigen (Medac), as well as a new automated epifluorescence immunoassay (InoDiag). A total of 405 patients with (n = 251) and without (n = 154) miscarriages were tested by all five tests. The prevalence of C. trachomatis-specific IgG antibodies as determined by the IF, cHSP60-Medac, MOMP-Medac, MOMP-RB and InoDiag was 14.3, 23.2, 14.3, 11.9 and 26.2%, respectively. InoDiag exhibited the highest sensitivity, whereas MOMP-RB showed the best specificity. Cross-reactivity was observed with C. pneumoniae using IF, MOMP-RB and InoDiag, and Parachlamydia acanthamoebae using the cHSP60 ELISA test. No cross-reactivity was observed between C. trachomatis and the other Chlamydiales (Neochlamydia hartmannellae, Waddlia chondrophila and Simkania negevensis). Given its high sensitivity, the new automated epifluorescence immunoassay from InoDiag represents an interesting alternative. The MOMP-based ELISA of R-Biopharm should be preferred for large serological studies, given the high throughput of ELISA and its excellent specificity.

Exposure to allergens of different cattle breeds and their relevance in occupational allergy

IntroductionCattle are an important source of allergens in the working area of farmers. Asthma caused by cow allergens is a significant occupational problem. Yet in allergological testing, the results of in vivo and in vitro diagnostic tests are often inconsistent even in cases with clearly cattle-related symptoms.Objectives and methodsThe aim of this study was to investigate four different commercial cow allergen extracts and to compare them with self prepared extracts of different cattle breeds by means of SDS-PAGE and immunoblotting using the sera of 42 German farmers with asthma and rhino-conjunctivitis caused by cattle contact.ResultsThe commercial extracts investigated in this study showed only minor differences in protein pattern. Using sera in immunoblotting experiments distinct bands were found for all symptomatic farmers, even in 13 farmers with a negative result in commercially available serological allergy tests. Bands with molecular weights in the range between about 11 and 67 kDa were observed; reactivity with the major allergen Bos d 2 at about 20 kDa was detected in all farmers, although it was not the strongest band in all cases.ConclusionsWe demonstrate for the first time the allergenic relevance of additional proteins with molecular weights of 14, 30, 55 and approx. 67–97 kDa in more than 50% of farmers with cattle related symptoms. One of our most striking results was that 32% of the investigated farmers with cattle related symptoms showed negative results with commercial serological tests but distinct reactions with cow allergen in immunoblotting experiments. The Bos d 2 content in hair showed differences between certain breeds whereas German Brown and Simmental had particularly higher quantities of Bos d 2 in their hair than breeds such as Holstein-Friesian. These results strongly support the following recommendation: test results with commercial extracts that are contradictory to the clinical symptoms should be supplemented by skin tests using extracts of the hair of the farmers’ own cattle.

Evaluación de dos pruebas comerciales para el serodiagnóstico de la tuberculosis pulmonar

Two commercial serological tests, Pathozyme-TB complex plus and Pathozyme-Myco IgG, were evaluated for their sensitivity and specificity in HIV negative patients with serum samples from pulmonary tuberculosis (TB) patients and tuberculin positive, healthy controls. The sensitivity for the two tests was 50 and 80% respectively and the specificity 95 and 80%. With a prevalence of pulmonary TB of 10% in symptomatic patients who consult our laboratory, the positive predictive values (PPV) for the two ELISA tests were 92 and 80%, and the negative predictive values (NPV) 98 and 80% respectively. In the same patient group, the AFB smear has a PPV of 100% and a NPV of 97%. We conclude that AFB smear is a better mass screening tool than ELISA in symptomatic patients who consult our laboratory. The test could be useful as a complementary test in excluding or confirming TB in selected, smear negative, symptomatic patients with high degree of clinical suspicion of active TB.

Correction: Commercial Serological Antibody Detection Tests for the Diagnosis of Pulmonary Tuberculosis: A Systematic Review

Correction: Commercial Serological Antibody Detection Tests for the Diagnosis of Pulmonary Tuberculosis: A Systematic Review

Commercial Serological Tests for the Diagnosis of Tuberculosis: Do they Work?

Karen R Steingart, Andrew Ramsay & Madhukar Pai† †Author for correspondence McGill University, Dept. of Epidemiology, Biostatistics & Occupational Health, Montreal, Canada and, Respiratory Epidemiology & Clinical Research Unit, Montreal Chest Institute 1020 Pine Avenue West, Montreal, Canada Tel.: +1 514 398 5422; Fax: +1 514 398 4503; madhukar.pai@mcgill.ca ‘Both pulmonary and extrapulmonary TB present diagnostic challenges.’

Commercial Serological Antibody Detection Tests for the Diagnosis of Pulmonary Tuberculosis: A Systematic Review

BackgroundThe global tuberculosis epidemic results in nearly 2 million deaths and 9 million new cases of the disease a year. The vast majority of tuberculosis patients live in developing countries, where the diagnosis of tuberculosis relies on the identification of acid-fast bacilli on unprocessed sputum smears using conventional light microscopy. Microscopy has high specificity in tuberculosis-endemic countries, but modest sensitivity which varies among laboratories (range 20% to 80%). Moreover, the sensitivity is poor for paucibacillary disease (e.g., pediatric and HIV-associated tuberculosis). Thus, the development of rapid and accurate new diagnostic tools is imperative. Immune-based tests are potentially suitable for use in low-income countries as some test formats can be performed at the point of care without laboratory equipment. Currently, dozens of distinct commercial antibody detection tests are sold in developing countries. The question is “do they work?”Methods and FindingsWe conducted a systematic review to assess the accuracy of commercial antibody detection tests for the diagnosis of pulmonary tuberculosis. Studies from all countries using culture and/or microscopy smear for confirmation of pulmonary tuberculosis were eligible. Studies with fewer than 50 participants (25 patients and 25 control participants) were excluded. In a comprehensive search, we identified 68 studies. The results demonstrate that (1) overall, commercial tests vary widely in performance; (2) sensitivity is higher in smear-positive than smear-negative samples; (3) in studies of smear-positive patients, Anda-TB IgG by enzyme-linked immunosorbent assay shows limited sensitivity (range 63% to 85%) and inconsistent specificity (range 73% to 100%); (4) specificity is higher in healthy volunteers than in patients in whom tuberculosis disease is initially suspected and subsequently ruled out; and (5) there are insufficient data to determine the accuracy of most commercial tests in smear microscopy–negative patients, as well as their performance in children or persons with HIV infection.ConclusionsNone of the commercial tests evaluated perform well enough to replace sputum smear microscopy. Thus, these tests have little or no role in the diagnosis of pulmonary tuberculosis. Lack of methodological rigor in these studies was identified as a concern. It will be important to review the basic science literature evaluating serological tests for the diagnosis of pulmonary tuberculosis to determine whether useful antigens have been described but their potential has not been fully exploited. Activities leading to the discovery of new antigens with immunodiagnostic potential need to be intensified.

An improved serodiagnostic test for Chagas' disease employing a mixture of Trypanosoma cruzi recombinant antigens.

Blood transfusion is one of the most important transmission routes of Chagas' disease, a major parasitic infection in Latin America. Therefore, screening for antibodies to Trypanosoma cruzi is mandatory in blood banks in South America. Most of the commercial serologic tests employ epimastigote antigens and show a high number of inconclusive and false-positive results, with high economic and social costs. An ELISA using a mixture of three T. cruzi recombinant antigens, B13, 1F8, and H49 (mix-ELISA), was evaluated, first with a panel of well-characterized sera from 617 patients with Chagas' disease and 277 nonchagasic individuals, living in nine countries of South and Central America. Subsequently, the mix-ELISA was evaluated with 451 samples, from an endemic area of Brazil (Goiás), that were rejected from several blood banks because they presented discrepant results by two commercially available kits (indirect immunofluorescence assay, indirect hemagglutination assay, and/or ELISA). The mix-ELISA exhibited 99.7 percent sensitivity and 98.6 percent specificity in the first evaluation with the 894 samples. In the second evaluation, 451 sera that had discrepant results in the first screening for Chagas' disease were further analyzed with the mix-ELISA. Upon consideration of the consensus results obtained with the trypomastigote excreted-secreted antigens blot test, a confirmatory test for Chagas' disease, the mix-ELISA led to a reduction in 99.6 percent in the number of discordant sera. The combination of three T. cruzi recombinant antigens in a multiantigen immunoassay was highly sensitive and specific for Chagas' disease diagnosis. It is proposed that it can be applicable in blood bank screening in conjunction with the conventional serologic tests.

Research agenda for pediatric gastroenterology, hepatology and nutrition: acid-peptic diseases. Report of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition for the Children's Digestive Health and Nutrition Foundation.

Research agenda for pediatric gastroenterology, hepatology and nutrition: acid-peptic diseases. Report of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition for the Children's Digestive Health and Nutrition Foundation.

Validation for use with coyotes (Canis latrans) of a commercially available enzyme-linked immunosorbent assay for Dirofilaria immitis

Serological tests offer a potentially powerful tool for monitoring parasites in wildlife populations. However, such tests must be validated before using them with target wildlife populations. We evaluated in coyotes (Canis latrans) the performance of a commercially available serological test used to detect canine heartworm (Dirofilaria immitis) in domestic dogs. We obtained 265 coyote carcasses and serological specimens from 54 additional coyotes from several regions of California, USA. We necropsied coyotes to determine the adult heartworm infection status. Blood was collected at necropsy on filter paper strips and allowed to dry; it was later eluted in a buffer solution, and the supernatant was tested for heartworm. Receiver operating characteristic (ROC) analysis was used to assess discriminatory power of the test and indicated a 93% probability that a randomly selected infected coyote would exhibit a higher enzyme-linked immunosorbent assay (ELISA) value than a randomly selected uninfected coyote. We estimated specificity at 96% (95% CI: 92-98%) for 165 uninfected coyotes and sensitivity at 85% (77-91%) for 100 infected coyotes, results similar to published values for the commercial serological test used with dog serum or plasma. Test performance was similar for filter paper specimens and supernatant of frozen whole blood collected in EDTA tubes (i.e. hemolyzed plasma). We found no difference in test performance among geographic or demographic coyote groups. Our findings support application of the test to filter paper or standard serological specimens for detection of heartworm in coyote populations.

Evaluation of invasive and non-invasive methods for the diagnosis of Helicobacter pylori infection in symptomatic children and adolescents

Multiple diagnostic methods are available for the detection of Helicobacter pylori infection, but at present no single one can be used as the gold standard. The aim of this study was to evaluate the diagnostic accuracy of 3 invasive and 2 non-invasive methods for detection of Helicobacter pylori infection in symptomatic children and adolescents. Prospective cohort study Peptic Disease outpatients service, Discipline of Pediatric Gastroenterology, Universidade Federal de São Paulo / Escola Paulista de Medicina. Forty-seven patients who underwent endoscopy because of dyspeptic symptoms. Endoscopy with gastric biopsies for 3 invasive (rapid urease test, histology and culture) and 2 non-invasive methods (a commercial ELISA serology and 13carbon urea breath test - isotope ratio mass spectrometry) for detection of Helicobacter pylori infection. Sensitivity, specificity, positive and negative predictive values of each method and agreement and disagreement rates between the methods. Forty-seven patients [mean age, 11y9mo (SD 2y10mo), 27 female and 20 male]; 62% of them were Helicobacter pylori-positive. All methods agreed in 61%, and were negative in 21% and positive in 40%. The greatest concordance between 2 methods occurred between the invasive methods: histology and rapid urease test (89.6%) and histology and culture (87.5%). The greatest sensitivity, considering Helicobacter pylori-positive cases, for any combination of 3 or more tests, was achieved by the rapid urease test (S=100%), followed by histology, serology and 13carbon-urea breath test (S=93.1%) and lastly by culture (S=79.3%). The highest specificity was obtained by histology (100%) and culture (100%), followed by the rapid urease test (84.2%), serology (78.9%) and 13carbon-urea breath test (78.9%). Our results suggest that among invasive methods, an association between the rapid urease test and histology constituted the best choice for the detection of Helicobacter pylori infection. If results of histology and the rapid urease test are different, serology may be recommended.

Evaluation of three commercial serological tests with different methodologies to assess Helicobacter pylori infection.

The sera of 142 Helicobacter pylori-positive and 32 H. pylori-negative patients were assessed by a desktop test (QuickVue), an enzyme-linked immunosorbent assay (ELISA) (HM-CAP), and a solid-phase, two-step chemiluminescent enzyme immunoassay (Immulite). These tests yielded sensitivities of 97, 97, and 91% and specificities of 97, 94, and 100%, respectively. In conclusion, the desktop test and the ELISA are more sensitive than the chemiluminescent enzyme immunoassay (P < 0.05). The chemiluminescent enzyme immunoassay has the advantage that it is fully automated.

Role of serology in the diagnosis of Lyme disease.

Numerous concerns regarding the potential for misdiagnosis of Lyme disease using commercial assays have been voiced by the US Food and Drug Administration (FDA). We attempted to clarify the clinical value of serologic testing for Lyme disease using the results of commonly marketed assays for detecting antibody to Borrelia burgdorferi, the organism that causes Lyme disease. We reviewed published studies on B burgdorferi test performance published through 1998, package insert labeling from FDA-cleared test kits for B burgdorferi, and Lyme Disease Survey Set LY-A from the College of American Pathologists. We assessed the sensitivity and specificity of commercial serologic tests (enzyme-linked immunosorbent assay [ELISA], immunofluorescence antibody [IFA], and immunodot) for diagnosis of Lyme disease. To reduce this risk of misdiagnosis, it is important that clinicians understand the performance characteristics and limitations of these tests. These tests, in common use in clinical or commercial laboratories, should be used only to support a clinical diagnosis of Lyme disease, not as the primary basis for making diagnostic or treatment decisions. Serologic testing is not useful early in the course of Lyme disease because of the low sensitivity of tests in early disease. Serologic testing may be more useful in later disease, at which time sensitivity and specificity of the test are improved. Positive or equivocal results on an ELISA, IFA, or immunodot assay requires supplemental testing with a Western blot assay. A negative result on the Western blot or ELISA indicates that there is no serologic evidence of infection by B burgdorferi at the time the sample was drawn.

Evaluation of three commercial enzyme-linked immunosorbent assay kits for diagnosis of Helicobacter pylori in Chinese patients

Most of the commercial serological assays for H. pylori are developed and validated in western countries. We evaluated the accuracy of three popular commercial ELISA tests for H. pylori in the Chinese population. Eighty dyspeptic patients were recruited and diagnosis of H. pylori infection was based on biopsy urease test, histology and urea breath test. Thirty-six patients (45%) were positive for H. pylori infection by two or more positive reference tests. Anti- H. pylori IgG antibody was detected by three commercial ELISA tests: GAP IgG (Bio-Rad), HM-CAP (Enteric Products) and Pyloriset EIA-G (Orion). The respective sensitivity, specificity, positive and negative predictive values of the three tests were: GAP IgG (50%, 97.4%, 93.8%, 71.7%), HM-CAP (72.7%, 68.4%, 66.7%, 74.3%) and Pyloriset EIA-G (75%, 86.4%, 81.8%, 80.9%). Despite the high accuracy reported in the West, the performance of these commercial serological tests was unsatisfactory when used in Chinese patients.

Racial differences in Helicobacter pylori seroprevalence in Singapore: correlation with differences in peptic ulcer frequency.

The aim of this study was to determine, first, whether racial differences exist in the seroprevalence of Helicobacter pylori infection in Singapore, and second, whether these differences correlate with racial differences in peptic ulcer frequency. A commercial serological test for immunoglobulin (Ig)G antibody to H. pylori which was 90% sensitive and 83% specific in our population was used to screen 403 adult blood donors of Chinese, Malay and Indian origin, aged between 15-60 years. Serum specimens from 84 paediatric patients admitted to the Paediatrics Department, National University of Singapore, with non-gastroenterological illnesses were also tested. In all three races, seroprevalence of H. pylori increased with age. Indians have the highest prevalence of infection followed by Chinese and Malays. Peptic ulcer prevalences are known to be highest in Chinese, followed by Indians and Malays. The Malays have the lowest prevalence of H. pylori and peptic ulcer among the three races in Singapore. Indians have a higher prevalence of H. pylori antibodies but a lower frequency of peptic ulcer than the Chinese. Racial differences in peptic ulcer frequency between Chinese and Indians are not explained by the prevalence of H. pylori infection; other environmental or genetic factors may be involved.

Type- and Group-Specific Continuous Antigenic Determinants of HTLV. Use of Synthetic Peptides for Serotyping of HTLV-I and -II Infection

The human T lymphotropic viruses (HTLV-I and -II) are relatively common in subpopulations of certain countries, notably intravenous drug abusers in North America. Infections with these malignancy-associated human retroviruses are hard to discriminate with currently available commercial serological tests. We studied the distribution of antigenicity and the degree of cross-reactivity of epitopes in gag and env of the two viruses. Sequences in the carboxyl terminus of the matrix protein (MA) and the middle of the outer glycoprotein (SU) reacted in a type-specific fashion, while sequences from the capsid protein (CA), the carboxyl terminus of SU, and conserved portions of the transmembrane protein (TM) mainly reacted in a group-specific fashion, correlating with the degree of sequence dissimilarity between the two viruses. The serological discrimination obtained with the peptides was evaluated in a panel of 25 sera where infection with HTLV-I or -II had been typed by competition in a p24 enzyme-linked immunosorbent assay (ELISA) or by the polymerase chain reaction (PCR). After processing peptide results in a computer program, a typing result concordant with earlier results was obtained in 21 of 25 sera. Of the remaining five sera, four were labeled "too weak for typing" and one "HTLV of uncertain type" by the program. They did not react sufficiently strongly or clearly with the peptides to allow classification. A combination of synthetic peptides may become useful for serotyping HTLV infection and become an alternative to Western blots for confirmation of HTLV positivity.

Comparative evaluation of the Iatron serological Candida check kit and the API 20C kit for identification of medically important Candida species

A newly developed commercial serological test (Iatron Laboratories, Inc., Tokyo, Japan) for the rapid identification of medically important species of Candida was evaluated against the API 20C (Analytab Products, Plainview, N.Y.) and the standard Wickerham assimilation and fermentation procedures. Our results indicated that the Iatron and the API 20C methods are 95% accurate since both permitted identification of 78 of 82 Candida isolates, representing eight medically important species. None of the tests on nine Cryptococcus, six Trichosporon, three Geotrichum, three Saccharomyces, and one Rhodotorula species yielded false-positive reactions. False-positive serological tests occurred with a species of Pichia and Candida rugosa. The API 20C procedure correctly identified C. rugosa but not the Pichia sp. The Iatron method permitted reliable identification of the Candida species in 10 min to 5 h, whereas the API 20C procedure required 48 to 72 h. Neither method could properly identify sucrose-negative Candida tropicalis or Candida lusitaniae isolates. In addition, Candida albicans isolates could be serotyped by the Iatron method.