Slide Agglutination Method Research Articles

Utility of A Single Widal Test in The Diagnosis of Typhoid Fever

Background & objectives: The clinical diagnosis of typhoid fever is difficult, as the presenting symptoms are often diverse and similar to those observed with other febrile illnesses. The definitive diagnosis of typhoid fever requires the isolation of Salmonella typhi or paratyphi from the patient concerned. Since patients often receive antibiotics prior to a confirmatory diagnosis, there is uncertainty that bacteria can be isolated from the blood cultures. Besides this, the facilities for blood culture are not always available or feasible. All these limitations have made Widal test the most utilized diagnostic test for typhoid fever. Many studies have produced data which had cast serious doubts on the value of the Widal Test and thus reappraisal of the role of a single Widal test is needed.Methods & materials: This study was carried out to determine the changes in clinical pattern of enteric fever. A total of 153 children, aged 0 to 14 years, diagnosed as typhoid fever (either positive blood culture for Salmonella typhi or paratyphi) were induced in the study. Of them, 86 children were with a definitive diagnosis of typhoid or paratyphoid fever as indicated by the isolation of S. typhi or S. paratyphi from the blood and 17 had negative blood culture but were clinically suspected of having typhoid fever. The control group was comprised of 50 children with non-typhoidal fevers The Widal test was carried out using rapid slide agglutination method and its accuracy was assessed by comparing the findings with that obtained through blood culture.Result: The mean age of the patients was 5.2 ± 2.8 years and the youngest and oldest patients were 0.7 and 14 years respectively and male to female ratio was roughly 1:1. Nearly one-quarter (24.6%) of the patients had been suffering from the disease for >10 days and the mean duration of illness was 8.2 ± 3.3 days. Widal Test result showed that an ‘O’ agglutinin titer of cut-off value e”1:40 gave a sensitivity of 87.2%, a specificity of 47.1%, a positive predictive value (PPV) of 89.2% and a negative predictive value (NPV) of 42.1%. The sensitivity and NPV decreased with the increase in titer levels and were 56.9% and 31.5% at cut-off value of e” 1:320, while the specificity and PPV increased with the increase in titer levels from 47.1% and 89.2% respectively at a titer of e”1:40 to 100% at a titer of e” 1:320. The ‘titer behaved in the same way as did the ‘O’ agglutinin titer. Similarly when H’ agglutinin was used the sensitivity and NPV decreased from 65% and 31.7% at a titer of e”1:40 to only 25% and 20% respectively at a titer of > 1:320, while specificity and PPV increased from 76.4% and 81.1% at >1:40 to 94.1% and 95.6% respectively at e” 1:320. When either ‘O’ or ‘H’ antibody titer of e”1:160 was used, a good sensitivity (71%), specificity (70.6%) and PPV (92.4%) resulted, though NPV decreased to 32.4%.Conclusion: The Widal test can be of diagnostic value when blood cultures are not available nor practically feasible.DOI: http://dx.doi.org/10.3329/bjch.v35i2.10377 Bangladesh J Child Health 2011; Vol 35 (2): 53-58

Development of a singleplex PCR assay targeting O-antigen modification genes for molecular serotyping of Shigella flexneri

To develop a singleplex PCR assay targeting O-antigen modification genes for molecular serotyping of Shigella (S.) flexneri. Eight pairs of primer for O-antigen synthesis and modification genes of S. flexneri were designed and used for developing an O-antigen modification gene-specific singleplex PCR assay to serotype 14 most common S. flexneri serotypes (1a, 1b, 1c, 2a, 2b, 3a, 3b, 4a, 4b, 5a, Y, X, Xv and F6). Bacterial pathogens which causing diarrheal disease were used for specificity detection. 106 S. flexneri clinical isolates were serotyped by this method and compared with the slide agglutination method. An O-antigen modification, gene-specific singleplex PCR was developed. When six singleplex PCR reactions were performed, 14 of the 15 recognized S. flexneri serotypes were identified, except for serotype Xv. The detection threshold ranged from 10 pg to 1 ng DNA in a 20 µl reaction system. A high concordance between the singleplex PCR assay and slide agglutination were observed when 106 S. flexneri strains of various serotypes were analyzed with an exception that 1 serotype Y strain showed that it was carrying the additional defective gtr II genes. This method showed advantages over the traditional slide agglutination methods, and was promising when under application in the following situations as clinical diagnosis.

Role of dental pulp in identification of the deceased individual by establishing ABO blood grouping and Rhesus factor

The study was conducted to emphasize the sensitivity and specificity of dental pulp in identifying the ABO Blood group, Rhesus factor and also to emphasize the role of dental pulp in forensic odontology to identify the deceased individual. The study was conducted on 60 patients. The samples obtained from finger-prick method from those 60 patients were considered as control and the samples obtained from the pulp were considered as case. The blood grouping, Rhesus typing for capillary blood drawn by finger prick was done by slide-agglutination method and the blood grouping, Rhesus typing for extracted dental pulp was done by absorption-elution method. Fifty seven teeth out of sixty showed positive results. Blood group elicited from capillary blood done by slide-agglutination method matched with that of the pulpal blood group elicited by absorption-elution method. Three showed negative results. As the teeth are the hardest, most stable biological material, resist adverse environmental conditions and the pulpal tissue inside the teeth is well protected, the blood group antigen from pulp remains stable for long. Thus, the high potential value of dental pulp tissue is highlighted in this study.

One‐stage prothrombin time, activated partial thromboplastin time, thrombin time, fibrin degradation product concentration, and antithrombin activity in healthy adult alpacas

Alpacas are increasingly presented to veterinarians for evaluation and care. Reports of alpaca reference intervals for one-stage prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time (TT), concentration of fibrin degradation products (FDP), and antithrombin (AT) activities are scarce or nonexistent. The aim of this study was to determine values for blood coagulation times (PT, aPTT, and TT), FDP concentrations, and AT activities in healthy adult alpacas. Of blood samples collected from 35 clinically healthy adult alpacas via jugular venipuncture and placed into sodium citrate and FDP tubes, 29 samples were assayable for coagulation testing. PT, aPTT, and TT were determined by physical (mechanical) clot detection; AT activity was determined using a thrombin-specific chromogenic substrate end-point assay; and FDP concentrations were determined by the slide agglutination method. Median values and ranges (minimum-maximum) were determined for PT (8.7 seconds, 6.6-11.2 seconds), aPTT (17.3 seconds, 11.9-22.5 seconds), TT (10.2 seconds, 5.4-16.0 seconds), and AT activity (123.3%, 104.8-144.2%). The mean concentration of FDP was <8 μg/mL. These values for coagulation times, FDP concentration, and AT activity will provide a useful starting point in the diagnostic evaluation of ill adult alpacas.

A Case of a Shiga Toxin Producing Escherichia Coli

We encountered a patient with hemolytic uremic syndrome (HUS) with persistent isolation of shiga toxin-producing Escherichia coli (STEC) for 3 weeks despite of having no clinical symptoms. STEC has been recognized as an important food-borne pathogen that causes severe diseases such as HUS. We characterized this STEC strain via a polymerase chain reaction, reverse-passive latex agglutination and the slide agglutination method. In this STEC strain, stx2 (shiga toxin), eaeA, tir, iha (adherence genes), espADB (type III secretion genes), and hlyA, ehxA, clyA (hemolysin genes) were present. The O antigen of the strain was non-typable.

OCCUPATIONAL BRUCELLOSIS AMONG HIGH RISKY HUMANS DURING THEIR CONTACTS WITH LIVESTOCKS IN BASRAH

Objective: To assess the seroprevalence of antibodies to occupational brucellosis among risky humans who are in contact with domestic animals. Methods: Seroprevalence for occupational brucellosis was done on 33 sera for humans (20 veterinary doctors, 5 veterinary assistants and 8 butchers) and 235 sera for domestic animals (102 sheep, 50 goats and 83 cattle) brought to Basrah slaughter house. Sera were examined by using slide and tube agglutination methods for the presence of antibodies to brucellosis. Results: The overall seropositive for brucellosis was 21.2% among high risky humans in Basrah Province, Iraq. The prevalence rates among veterinary doctors, veterinary assistants and butchers were 15%, 60% and 12.5% respectively. In this study, the overall seroprevalence among domestic animals was 23.4%. However, the positive rate among sheep, goats and cattle was 39.2%, 6%, and 14.5% respectively. Conclusion: Occupational brucellosis remains a major public health problem and one of the zoonotic disease for human beings during their work.

Distribution of Virulence Genes and Their Association of Serotypes in Pathogenic Escherichia coli Isolates From Diarrheal Patients in Korea

ObjectivesTo characterise the genetic and serological diversity of pathogenic Escherichia coli, we tested 111 E coli strains isolated from diarrhoeal patients in Korea between 2003 and 2006. MethodsThe isolates were tested through polymerase chain reaction (PCR) and slide agglutination method for the detection of virulence genes and serotypes, respectively. To compare the expression of Shiga toxin (stx)-1 and stx2 genes, real-time quantitative reverse-transcriptase PCR and rapid exprssion assay, reversed-passive latex agglutination, were performed. ResultsForty-nine Shiga toxin-producing E coli (STEC) strains and 62 non-STEC strains, including 20 enteropathogenic E coli, 20 enterotoxigenic E coli, 20 enteroaggregative E coli, and 2 enteroinvasive E coli were randomly chosen from the strains isolated from diarrhoeal patients in Korea between 2003 and 2006. PCR analysis indicated that locus of enterocyte effacement pathogenicity island, that is, eaeA, espADB, and tir genes were present in STEC, enteropathogenic E coli, and enteroinvasive E coli. Quorum sensing-related gene luxS was detected in most of pathogenic E coli strains. Major serotypes of the STEC strains were O157 (26%) and O26 (20%), whereas the non-STEC strains possessed various serotypes. Especially, all the strains with serotype O157 carried stx2 and the tested virulence factors. Of the STEC strains, the data of real-time quantitative reverse-transcriptase PCR and reversed-passive latex agglutination tests showed that messenger RNA- and protein expression of stx2 gene were higher than those of stx1 gene. ConclusionOur results provide the epidemiological information regarding the trend of STEC and non-STEC infections in the general population and show the fundamental data in association of serotypes with virulence genes in diarrhoeagenic E coli strains from Korea.

Diagnostic sampling strategies for virulent ovine footrot: Simulating detection of Dichelobacter nodosus serogroups for bivalent vaccine formulation

Dichelobacter nodosus is a slow-growing anaerobic bacterium that is the causative agent of virulent ovine footrot. Vaccination targeted at up to two specific serogroups can eliminate those serogroups from infected flocks, but requires identification of serogroups present in infected flocks. Serogroups can be identified using slide agglutination or polymerase chain reaction (PCR) methods. The objectives of this project were to use stochastic simulation modeling to estimate the efficacy of sampling strategies encompassing 5–40 sheep per flock and 2–4 colonies per sheep, and to compare efficacies based on slide agglutination or multiplex PCR test results. Foot swabs collected from sheep in 12 flocks were used as the basis for a sampling strategy simulation model.None of the evaluated sampling strategies identified the two most common serogroups in the flock, or all serogroups present in the flock, in 95% of iterations. However, a simulated sample of 22 sheep/flock and 2 colonies/sheep resulted in a simulated vaccine that protected 95% of the sheep that could be protected by a single bivalent vaccine, while a sample of 24 sheep/flock and 2 colonies/sheep resulted in a series of simulated bivalent vaccines that protected 95% of diseased infected sheep. The difference in outcome was due to the distribution and frequency of serogroups within certain flocks where some serogroups were uncommon and others dominant. A sampling strategy (>40 sheep/flock, 4 colonies/sheep) that will identify the two most common serogroups in a flock 95% of the time may not be cost effective. Evaluating efficacy based on the expected effect on the flock may be more useful than one which seeks to determine the most common serogroups. These findings are broadly applicable to diseases where more than one strain or type of pathogen may be present and must be represented in a vaccine.

Efficacy of a chairside diagnostic test kit for estimation of C-reactive protein levels in periodontal disease

Background:C-reactive protein [CRP] levels increase to hundreds of mg/mL within hours following infection. Studies have shown that serum CRP levels were elevated in periodontal disease. However, in all the previous studies, CRP levels were measured by using high-sensitivity CRP assay kits with minimal detection limits of 0.1 to 3 mg/L, which was much below the normal value of 10 mg/L. These high-sensitivity CRP assays need a proper laboratory setup, and these methods cannot be used as a routine chair-side test in the dental office.Aim:The purpose of this study was to investigate the serum CRP levels in subjects with periodontal disease by using a rapid chair-side diagnostic test kit with a lower detection limit of 6 mg/L and to compare the CRP levels before and after periodontal therapy.Materials and Methods:A total of 45 systemically healthy subjects were selected for the study. Subjects were divided into three groups: group A: healthy controls, group B: gingivitis, group C: periodontitis. Serum levels of CRP were determined by using a latex slide agglutination method with commercially available kit with lower detection limit of 6 mg/L.Results:CRP was negative in all the 15 subjects in groups A and B at baseline, 7th and 30th day. CRP was positive only in 2 subjects in Group C at baseline and 7th day.Conclusion:Estimation of serum CRP by using a rapid chair-side diagnostic test kit is not of any significance in subjects with periodontitis.

Characteristics of Pseudomonas aeruginosa isolates from intensive care unit

Abstract The study looked at the antimicrobial resistance patterns, serotypes, molecular types, metallo beta-lactamase, and chromosomal betalactamase enzymes of P. aeruginosa strains isolated from the patients and the staffs of the intensive care unit. P. aeruginosa isolates from the patients as nosocomial pathogens and from the staffs were evaluated for their susceptibilities to the antimicrobials by the disk diffusion and E-test methods. Metallo beta-lactamase enzymes were investigated by E-test, the inducibility of β - lactamase enzymes were detected by the disk antagonism test. Serotyping was performed by slide agglutination method. The P. aeruginosa isolates were typed by pulsed field gel electrophoresis. Twenty-five P. aeruginosa strains from the patients and three from the staffs were isolated. Fifteen P. aeruginosa, eleven of which composed of MDR bacteria, were found in serogroup E, 7 strains in G, 4 strains in B, and 1 strain in serogroup A. In all 12 bacteria in the MDR and serogroup E, metallo beta-lactamase enzyme was found to be positive. And in other 15 strains, except the bacterium which could not be serotyped, chromosomal beta-lactamase was found to be positive. The result of the molecular typing showed PFGE A pattern. In conclusion, a pattern in PFGE which included bacteria from MDR and serogroup E, G which was observed in the P. aeruginosa strains which was isolated from the staff’s hands and from the 5 patients, and PFGE F pattern were found to be observed the most. Finally, the two different clonal strains were found to be established in the intensive care.

Serotyping and Population Genetics of Invasive Haemophilus influenzae

One of the objectives of a recent study by Satola et al. ([2][1]) was to use PCR capsule gene typing to evaluate the accuracy of the slide agglutination method for serotyping (SAST) Haemophilus influenzae . Of the 360 invasive H. influenzae isolates tested, 64 (or 17.5%) were found to be

Prevalence of β-lactamase-nonproducing ampicillin-resistant Haemophilus influenzae and Haemophilus influenzae type b strains obtained from children with lower respiratory tract infections

The prevalence of strains with ampicillin (ABPC) resistance among Haemophilus influenzae strains isolated from the nasopharynx of children with lower respiratory tract infections has increased significantly during the 6 years from 2000, when it was 41.9%, to 2005, when it reached 60.1%. From 2002, the prevalence exceeded 50%, and the prevalence of beta-lactamase-nonproducing ABPC-resistant (BLNAR) strains with a minimum inhibitory concentration (MIC) of ABPC of over 4 microg/ml doubled, from 28.2% in 2002 to 54.7% in 2005. In H. influenzae strains obtained from the nasopharynx of children with lower respiratory tract infections between April 2004 and March 2006, identification of serotype b was defined, using the slide agglutination method. The frequency of isolation of H. influenzae type b (Hib) strains was then measured and the ABPC resistance conditions of the Hib strains were also evaluated. The frequency of the Hib strains was found to be 30 out of 479 strains, 6.3%. Of these 30 strains, BLNAR accounted for 53.3% (16 strains), approximately the same frequency of isolation as that of the BLNAR isolated from all H. influenzae strains during the same period. In Japan, the prevalence of BLNAR strains among clinically isolated H. influenzae strains has continued to increase, and the frequency of isolation of BLNAR strains among Hib strains has also continued to rise. As a countermeasure, attempts at improving resistance have been made through judicious antibiotic use, but concern that the choice of antibiotics for Hib meningitis may become complicated has sparked a keen interest in the introduction of Hib conjugate vaccine.

Comparison of two slide agglutination serotyping methods and PCR-based capsule typing for the characterization of Haemophilus influenzae serotypes

Ninety-three nasopharyngeal Haemophilus influenzae isolates were serotyped by two slide agglutination methods (SAST 1 and SAST 2) and the results compared with those obtained by capsule type-specific PCR. SAST 1 presented a low correlation with results obtained by PCR (75.2%) while SAST 2 showed a better agreement with the molecular technique results (93.5%). These findings suggest that SAST 2 could be an alternative method for adequate detection of H.influenzae type b.

Evaluation of six commercial identification kits for the identification of Staphylococcus aureus isolated from bovine mastitis

Comparison of six commercially available in human medicine well-established slide agglutination systems for the identification of Staphylococcus aureus. Slide agglutination tests were compared with the conventional tube coagulase test, biochemical identification and with the molecular identification by polymerase chain reaction (PCR) amplification of species-specific parts of the gene encoding the 23S RNA. Systems evaluated included Masta-Staph (Mast Diagnostics), Staphylase-Test (Oxoid), Staphytect-Plus (Oxoid), Staphyloslide Latex (Becton Dickinson), Slidex Staph Plus (bioMerieux) and Dry Spot Staphytect Plus (Oxoid). A total of 141 staphylococcal strains isolated from cases of bovine mastitis including 90 S. aureus, 14 Staphylococcus epidermidis, 10 Staphylococcus warneri, 13 Staphylococcus xylosus, 11 Staphylococcus haemolyticus and three other coagulase-negative staphylococci were tested with each method. Staphylococcus aureus strains were selected by macrorestriction analysis with pulsed field gel electrophoresis (PFGE). Only genetically unrelated strains were included in the study. The sensitivities and specificities of the test were as follows: Masta-Staph 86.7 and 90.1%, Staphylase-Test 78.4 and 85.1%, Staphytect-Plus 81.1 and 86.5%, Staphyloslide Latex 77.8 and 84.4%, Slidex Staph Plus 77.8 and 84.4%, Dry Spot Staphytect Plus 75.6 and 83.0%. The results of this evaluation suggest that the six slide agglutination methods tested can provide rapid identification of S. aureus also from bovine mastitis. The sensitivity and specificity seems to be less than those reported from human S. aureus isolates. This is one of the first comparative reported investigations about the applicability of different commercially available slide agglutination tests for the detection of S. aureus from bovine mastitis using PFGE selected clinical isolates.

Comparison of the Denka Seiken slide agglutination method to the quellung test for serogrouping of Streptococcus pneumoniae isolates.

This study compared a slide agglutination test (Denka Seiken, Tokyo, Japan) to the "gold standard" quellung reaction (Pneumotest; Statens Serum Institut, Copenhagen, Denmark) for the serogrouping of pneumococci. Two hundred clinical isolates of Streptococcus pneumoniae were used for the comparison. Each assay was performed according to the manufacturer's instructions. There was an overall agreement of 95.7% between the two methods. Only 4 of 10 isolates of serogroup 22 were detected with the slide agglutination assay. Two isolates that were untypeable by the Pneumotest method were typed as serogroups 6 and 31 by the slide agglutination method. The Pneumotest method was unable to type 22 isolates, and the slide agglutination method was unable to type 16 isolates. The slide agglutination method compares favorably with the Pneumotest method and is easier to perform and to interpret.

Evaluation of methodology for serotyping invasive and nasopharyngeal isolates of Haemophilus influenzae in the ongoing surveillance in Brazil.

To assess the magnitude of discrepant results obtained by routine Haemophilus influenzae serotyping, 258 isolates, collected by the epidemiological surveillance system in Brazil from individuals with invasive diseases or carriage, were evaluated by two slide agglutination (SlAg) methods: SlAg method 1, by which strains were initially screened with a serotype b-specific antiserum, and SlAg method 2, by which strains were tested against all serotype-specific antisera in parallel. Investigators comparing results of the two SlAg methods with those obtained by capsule type-specific PCR were blinded to the method used. The serotype prevalence rates found by the three methods were significantly different, involving discrepancies mainly between serotype b and noncapsulated (NC) isolates. For invasive isolates (n = 131), the overall agreement rate between SlAg method 1 or 2 and PCR was 68.0 or 88.3%, respectively, whereas for colonizing isolates (n = 127) the corresponding rate was 46.5 or 94.2%, respectively. SlAg method 2 improved the ascertainment of serotypes over that obtained with SlAg method 1, demonstrating good correlation with PCR. Use of the polyvalent antiserum as a screening reagent for SlAg for invasive and colonizing isolates showed poor discriminatory power, with a sensitivity of 65.8% and a specificity of 91.7%. We stress the importance of using a well-standardized SlAg methodology and suggest that reference laboratories should utilize PCR routinely to confirm SlAg results and to check all nonspecific SlAg reactions and apparent NC isolates by SlAg in order to provide reliable data on the prevalence of H. influenzae serotypes in the H. influenzae type b vaccine era.

Listeria monocytogenes serotype identification by PCR.

Serotyping is a universally accepted subtyping method for Listeria monocytogenes. Identification of the strain serotype permits differentiation between important food-borne strains (1/2a, 1/2b, and 4b) and provides a "gold standard" for comparing isolates analyzed in different labs and with different techniques. Although an efficient enzyme-linked immunosorbent assay serotyping protocol was described recently, identification of PCR serotyping primers would further increase the ease and accessibility of this classification system. Serotyping PCR primers were designed from variable regions of the L. monocytogenes genome. Three primer sets were used in conjunction with a previously described Division III primer set in order to classify 122 L. monocytogenes strains into five serotype groups [1/2a(3a), 1/2b, 1/2c(3c), 4b(d,e), and 4a/c]. Results of the PCR method agreed with those of the conventional slide agglutination method for 97, 100, 94, and 91% of strains belonging to serotypes 1/2a, 1/2b, 1/2c, and 4b, respectively.

Evaluation of a new serotyping kit for Streptococcus pneumoniae

A new serotyping test kit (Streptococcus pneumoniae antisera "Seiken" set; Denka kit) was evaluated for 285 strains of Streptococcus pneumoniae in comparison with the standard capsular reaction (Quellung test). This new kit is based on the slide-agglutination method and is composed of eight pool sera, 40 group or type sera and 41 specific type sera. All serotyping results by using the Denka kit were completely identical to those obtained by using the conventional Quellung test. For types and groups, sensitivity and specificity were 100 and 100 %, respectively. For specific types, sensitivity and specificity were 100 and 100 %, respectively. The Denka kit is relatively rapid (mean test time, 5 min, versus 15 min by Quellung test), cheap (0.5 US$ per test, versus 1.4 US$ per Quellung test), easy to perform and does not require special equipment. The Denka kit may be useful for fieldworkers in developing countries involved in epidemiological surveys and vaccine development.

Correlación entre la tipificación capsular de aislamientos colombianos de Haemophilus influenzae por el método de aglutinación en lámina y la técnica de PCR.

In 1998, the Colombian government initiated an immunization program for children under one year of age with a Haemophilus influenzae capsular type b conjugate vaccine. After two years, the surveillance program of the Colombian Instituto Nacional de Salud Microbiology Group reported a 40% decrease in meningitis cases caused by H. influenzae. This effect was attributed to the vaccination. The surveillance program uses the standardized slide agglutination technique to serotype H. influenzae. The current study validated the accuracy of the slide agglutination method by means of the PCR technique. From children under five years of age, 146 isolates were obtained. These were collected between 1999 and 2002, and were characterized by biochemical tests and serotyped by the INS as part of the surveillance program. PCR confirmed 93% of the H. influenzae serotype b and 92% of the other serotypes. When the slide agglutination technique is conducted under a strict quality control program, it remains a sensitive and specific tool for serotyping H. influenzae.

A proposed serotyping system for Flavobacterium psychrophilum.

To develop a common serological system for rapid and routine identification of the fish pathogen Flavobacterium psychrophilum. Thirty-four isolates of Fl. psychrophilum from different fish species and different geographical areas were typed using a slide agglutination test and an enzyme-linked immunosorbent assay (ELISA). Seven host-dependent serovars (1: salmon; 2: trout; 3: trout; 4: eel; 5: carp; 6: tench; 7: ayu) were found. Serovar 2 was divided into two antigenic subgroups (2a and 2b). The results achieved by both slide agglutination and ELISA methods were totally consistent with each other. Although both techniques proved to be simple to carry out and useful, only the ELISA allowed identification of Fl. psychrophilum serovars using unabsorbed antiserum and whole-cells as antigens. This paper proposes a harmonized scheme for serological identification of Fl. psychrophilum to be used for diagnostic and seroepidemiological studies of the diseases it causes.