Performance of Widal test and stool culture in the diagnosis of typhoid fever among suspected patients in Dar es Salaam, Tanzania.

OBJECTIVE: We set an experiment to determine the diagnostic performance of the Widal test and stool culture in typhoid-suspected cases attending tertiary hospitals in Dar es Salaam, Tanzania using blood culture as a golden standard. We also evaluated the agreement between Widal, stool and blood culture. RESULTS: This was a cross-sectional study conducted between June and September 2018, in three Regional Referral Hospitals in Dar es Salaam, Tanzania. A total of 158 typhoid-suspected cases were enrolled, after obtaining an informed consent. Of the 158 patients participated in the study, 128 (81%) tested positive for the Widal test and 17 (11%) patients were stool culture positive. Widal test recorded 81.5% sensitivity, 18.3% specificity, 10.1% positive predictive value and 89.7% negative predictive value. Stool culture showed 31.3% sensitivity, 91.5% specificity, 29% positive predictive value and 91.5% negative predictive value. In conclusion, Widal test is not reliable for diagnosis of typhoid fever since false positive and negative results are common. In addition, Widal test recorded poor agreement with the blood culture (kappa = 0.014, p < 0.05) while stool culture had strong agreement with the blood culture (kappa = 0.22, p < 0.05).

Exploring global and country-level barriers to an effective supply of leishmaniasis medicines and diagnostics in eastern Africa: a qualitative study.

OBJECTIVES: To understand stakeholders' perceptions of the access barriers to quality-assured diagnostics and medicines for leishmaniasis in the high-burden region of eastern Africa, and to identify key bottlenecks to improve the supply of commodities for neglected tropical diseases. DESIGN: Desk reviews and qualitative in-depth interview study with purposive sampling. METHODS: A landscape analysis through literature and desk review was performed. Next, 29 representatives from international organisations, non-governmental agencies, national control programmes from six countries (Ethiopia, Kenya, Somalia, South Sudan, Sudan and Uganda) and manufacturers were interviewed between May and July 2018. Participants were selected purposively and expanded through a snowballing technique.Data analysis was aided by NVivo, applying the framework method as a part of the thematic content analysis approach. RESULTS: The barriers along the visceral leishmaniasis (VL) supply chain were identified as emerging themes, grouped across supply chain activities and health systems component(s). Stakeholders expressed the perception of progress, but bottlenecks persist. VL medicines, in general, lack multisource production capacity and with small market volume, expansion of suppliers is difficult. Procurement is plagued by forecasting difficulties, complex regulatory policies and procedures, and distribution challenges. Weak communication and coordination across different levels resulted in shortages and loss of trust among different actors. Cross-cutting issues spanned from limited political and resource commitment due to low awareness and limited in-country capacity. However, study respondents were optimistic to pursue several remedies, most importantly to build bridges between supply and demand sides through continued dialogue and collaborations. Diagnostics supply has mostly been overlooked; thus, improved investment in this area is needed. CONCLUSIONS: Addressing supply barriers in eastern Africa requires consistent, specific efforts at the global and national levels, progressing from current partnerships and agreements. Priority actions include pooled procurement, improved forecast, and increased commitment and resources. Sustainability remains an elusive goal, yet to be integrated into discussions moving forward.

Comparison of Indirect Immunofluorescence and Passive Particle Agglutination for the Detection of Mycoplasma Pneumoniae Antibodies.

BACKGROUND: Mycoplasma pneumoniae (MP) is the most predominant pathogen causing pneumonia. The present study compares two serological assays, the indirect immunofluorescence assay (IFA) and the passive particle agglutination assay (PPA), in order to assist clinicians in selecting accurate diagnosis methods. METHODS: Sera from 127 patients suffering from mycoplasma pneumonia and 76 from the healthy group were analyzed simultaneously by PPA and IFA. Receiver operating characteristic analyses were performed to evaluate the detection value of PPA and IFA for mycoplasma pneumoniae. The kappa coefficient was analyzed to evaluate the agreement between the IFA and PPA assay. RESULTS: The AUC of PPA and IFA was more than 0.70, suggesting both assays were acceptable in clinical efficacy for detecting mycoplasma pneumoniae. When ± 1:40 antibody titers were interpreted as negative, PPA showed the highest specificity, Youden index, and AUC (86.84%, 65.58%, and 0.828, respectively), and the kappa coefficient between PPA and IFA was 0.360. CONCLUSIONS: IFA and PPA assays have advantages and disadvantages in the detection of MP antibodies. MP anti-bodies ± 1:40 antibody titers should be interpreted as negative to improve PPA detection abilities, and the consistency of the two methods was regular agreement. Clinicians should detect MP antibodies simultaneously with two methods or analyze paired samples with one method for diagnosing whether or not MP infection is present.

Typhoid fever: misuse of Widal test in Libya.

The worldwide gold standard of diagnosing of enteric fever depends on the isolation of Salmonella enterica serovar Typhi from a patient's bone marrow and/or blood culture. In Libya clinicians are heavily dependent on the Widal test for diagnosis of enteric fever which has been used without determining the locally appropriate threshold titer, because the laboratories lack the skilled, experienced personnel and appropriate facilities to detect and serotype Salmonella isolates. To improve the diagnosis process, clinical management and reliability of public health measures, there is an urgent need for the effective training of laboratory technicians and to provide resources to culture Salmonella species according to published guidelines. Clinicians should understand the limitations of Widal test and recognize that it cannot be expected to give a reliable diagnosis.

Brief Report: spuriously low serum IgG4 concentrations caused by the prozone phenomenon in patients with IgG4-related disease.

OBJECTIVE: To determine the frequency of the prozone effect in patients with IgG4-related disease (IgG4-RD). METHODS: After identifying the prozone effect in an index patient with IgG4-RD, we examined additional samples to determine the frequency of this phenomenon. Thirty-eight serum samples obtained from patients with IgG4-RD whose results had been reported previously were retested. The serum IgG4 concentrations determined by this repeat analysis were compared with the originally reported values. RESULTS: In 10 (26%) of 38 patients, the originally reported IgG4 values were falsely low; the prozone effect was identified in each of these 10 samples. Correction of the prozone effect by sample dilution led to revision of the mean serum IgG4 concentration in the 10 samples, from 26 mg/dl to 2,008 mg/dl (normal range 2.4-121 mg/dl). All 10 patients whose samples were affected by the prozone effect had active IgG4-RD. Failure to detect the elevated serum IgG4 concentrations had a direct impact on the decision not to institute treatment in these patients. CONCLUSION: The prozone effect may lead to major underestimations of IgG4 concentrations in patients with IgG4-RD and offers a potential explanation for the poor correlation observed between disease activity and serum IgG4 levels in some patients. This phenomenon should be considered if the serum IgG4 measurement appears discordant with the clinicopathologic diagnosis and the clinical assessment of disease activity.

[Performance of Cholera-SMART and Pathogen-Detection-Kit in the quick diagnosis of cholera]. / Desempeño de los sistemas Cholera-SMART y Pathogen-Detection-Kit en el diagnóstico rápido del cólera.

OBJECTIVES: To compare the performance of two rapid systems for the diagnosis of cholera with the culture method, and to propose a strategy for improving the specificity and sensitivity of these systems and reducing the costs involved in making a diagnosis. METHODS: The following institutions participated in the study: the National Bacteriology Referral Center (Centro Nacional de Referencia en Bacteriologia, CNRB) of the Costa Rican Institute for Research and Teaching in Nutrition and Health (Instituto Costarricense de Investigacion y Ensenanza en Nutricion y Salud, INCIENSA) and various hospitals in the provinces of Alajuela, Guanacaste and San Jose, in Costa Rica. A total of 237 feces samples were used to asses the performance of two tests for the rapid detection of Vibrio cholerae 01: the Pathogen Detection Kit (PDK, Intelligent Monitoring Systems, Gainesville, Florida, USA) and Cholera-SMART (New Horizons Diagnostics Corp., Columbia, Maryland, USA), both when applied directly (direct SMART and direct PDK) and when applied to specimens cultured in broth-enriched medium for 6 hours (SMART-6 and CPK-6) and for 18 hours (SMART-18 and PDK-18) at 37 degrees C in alkaline peptone water. Liquid and partially formed stools were cultured and examined by means of the rapid direct test; when the initial result was negative, the tests were repeated after culture for periods of 6 and 18 hours. Rectal and fecal swabs were obtained from feces cultured in enriched-broth medium for 6 and 18 hours. In addition, we studied the sensitivity of the rapid testing systems by using pure cultures of V. cholerae 01 (strain SOS-833, CNRB, Costa Rica) that were incubated for 18 to 24 hours, and we assessed the usefulness of observing motility under the microscope in order to rationalize the use of rapid methods. RESULTS: The sensitivity of the direct SMART test and of the direct PDK test was 100% when samples obtained from liquid and partially formed stools and from the intestinal contents of dead bodies were used. With these samples, the direct SMART procedure showed a specificity of 100%, whereas the direct PDK procedure showed a specificity that ranged from 85.7% to 77.4%, depending on the type of sample. False positives obtained with the direct PDK method turned out to be negative with PDK-6 and PDK-18. Among the rectal and fecal swabs of persons with and without diarrhea or who had received prior treatment with antibiotics, three results that were negative with the SMART-6 procedure and two that were negative with the PDK-6 procedure turned out to be positive with the SMART-18 and PDK-18 procedures, respectively. Both systems showed excellent concordance (kappa index above 0.9) throughout. Both systems were sensitive to 6 x 10(7) colony-forming units per milliliter (cfu/mL), which was concordant with the microscopic observation of 10 microorganisms or more per field with the type of motility that characterizes vibrios (at 1000 x magnification). Samples having fewer than 10 microorganisms with the motility that characterizes vibrios had concentrations between 6 x 10(3) and 6 x 10(6) cfu/mL and became positive only after incubation in enriched-broth medium for 6 to 18 hours. We propose a strategy for diagnosing the presence of V. cholerae 01 infection in less time than it takes with traditional methods, with positive and negative predictive values of 100%. CONCLUSIONS: The SMART and PDK systems make it possible to accurately diagnose cholera quickly, don't require sophisticated equipment or highly qualified technical personnel, and perform satisfactorily in field conditions. Through the proposed strategy, it becomes possible to improve the specificity and sensitivity of these systems and to reduce the cost of making a diagnosis, thus making them suitable for use in cholera surveillance in low-income settings where this disease is a serious public health problem.

Epidemiology of visceral leishmaniasis in Atbara River area, eastern Sudan: the outbreak of Barbar El Fugara village (1996-1997).

An outbreak of visceral leishmaniasis (VL) started in 1995 in the Atbara River area in eastern Sudan. This article reports on this outbreak and on the clinical and immunological studies that were carried out in a village, with the highest incidence of VL cases, from 1996 to 1997. A significant increase in VL incidence was recorded in a dozen villages in this area; one village, Barbar El Fugara accounted for half of the total number of cases recorded at the regional hospital. A total of 152 VL and 61 post kala-azar dermal lesion (PKDL) cases were diagnosed and treated in Barbar. Household (n = 671) and school (n = 276) surveys were performed using the leishmanin skin test (LST) and the direct agglutination test (DAT). LST positivity was 23.1 and 15.7%, whereas DAT positivity was 8.9 and 26.4% in both surveys, respectively. No gender differences were observed in either test. Unlike DAT, LST positivity was predominant in the higher age groups that also exhibited lower prevalence of VL. Few individuals were positive by both tests (1.3%, 5.2%) while the majority (68.8%, 64.8%) had no evidence of acquired immune response, suggesting either a role of innate immunity in preventing parasite establishment or, unexpectedly, lack of exposure to Leishmania. Subclinical parasitism was also demonstrated, as evidence of both acquired humoral and cellular immune responses was observed in individuals with no past history of the disease. The wide spectrum of L. donovani/human interactions may be explained by differential exposure to environmental risk factors, parasite strain polymorphisms or host genetic makeup.

The increase in occurrence of typhoid fever in Cameroon: overdiagnosis due to misuse of the Widal test?

This study investigates the cause of an apparent increase in occurrence of typhoid fever in Cameroon. The reasons explored include an overdiagnosis of the illness related to poor performance of the Widal test in laboratories and interpretation by prescribers. Questionnaires were used in 1996 to evaluate the use and interpretation of the Widal test, and checklists were used to assess its laboratory performance in 2 of the 10 provinces in Cameroon. The majority of prescribers from 20 health facilities (an average of 76% of the doctors and 61% of the nurses) could detect patients who truly had positive Widal tests and needed treatment. However, an average of 48% of the doctors and 84% of the nurses would treat patients who did not require treatment based on the Widal test result. Patients may therefore be treated unnecessarily. Most (88%) of the visited laboratories performed the Widal rapid slide agglutination test as opposed to the conventional tube agglutination test. About 14% of the laboratories that performed the rapid slide agglutination test had a score above average for each criterion evaluated. Misdiagnosis of typhoid fever leads to unnecessary expenditure and exposure of patients to the side-effects of antibiotics. In addition, misdiagnosis may result in delayed diagnosis and treatment of malaria, and other acute febrile illness.

Rapid diagnosis of cholera by coagglutination test.

In this study the coagglutination test for the rapid diagnosis of cholera is evaluated in comparison with the conventional culture method. A total of 553 stool specimens were processed from cases of acute gastro-enteritis. The sensitivity and specificity of coagglutination test was 92.77% and 95.65% respectively. The coagglutination test is found to be simple, reliable and rapid method for the diagnosis of cholera.

Mycobacterium leprae particle agglutination in diagnosis and monitoring of treatment of leprosy.

IgM antibody levels against PGL-1 antigen were measured by M. leprae particle agglutination (MLPA) in 156 untreated leprosy patients. The seropositivity rate was much higher in newly untreated MB patients (84.7%) than in PB patients (19.7%). The mean MLPA titers in MB and PB declined significantly after 1 month of MDT (p < 0.001). Seropositivities in control serum specimens were 11.3 per cent in active pulmonary tuberculosis patients, 2.6 per cent in dermatologic patients and 4.4 per cent in a healthy population, in low titers. The study confirms that, anti PGL-1 assay using MLPA is a sensitive and specific diagnostic tool for the diagnosis of leprosy especially MB patients. Additionally, it provides an alternative tool in monitoring leprosy patients under MDT.

Rapid identification of Burkholderia pseudomallei in blood cultures by a monoclonal antibody assay.

Burkholderia pseudomallei is the causative agent of melioidosis. In northeast Thailand, this gram-negative bacterium is a major cause of mortality from septicemia. The definitive diagnosis of this disease is made by bacterial culture. In this study, we produced a monoclonal antibody (MAb) specific to the 30-kDa protein of B. pseudomallei by in vivo and in vitro immunization of BALB/c mice with a crude culture filtrate antigen. The MAb could directly agglutinate with all 243 clinical isolates of B. pseudomallei but not with other gram-negative bacteria, except for one strain of Burkholderia mallei. However, the MAb cross-reacted with the gram-positive Bacillus sp. and Streptococcus pyogenes. B. pseudomallei in brain heart infusion broth (BHIB) subcultured from a BacT/Alert automated blood culture system could be identified by simple agglutination with this MAb assay. The sensitivity and specificity of direct agglutination compared to the "gold standard," the culture method, were 94.12 and 98.25%, respectively. However, the MAb adsorbed to polystyrene beads or latex particles directly identified the bacterium in blood culture specimens and in BHIB subcultured from a BacT/Alert automated blood culture system. The sensitivity of the latex agglutination test was 100% for both blood culture and BHIB specimens. The specificity was 85.96 and 96.49% for the blood culture and BHIB specimens, respectively. The specificity could be increased if the nonspecific materials in the blood culture broths were eradicated by centrifugation at low speeds. Thus, a combination of blood culture and the agglutination method could be used for the rapid diagnosis of melioidosis in the routine bacteriological laboratory. This method could speed up detection of the bacterium in blood culture by at least 2 days, compared to the conventional bacterial culture method. In addition, the MAb is stable at room temperature for 2 weeks and at 4, -20, and -70 degrees C for at least 1 year. The latex reagent was stable for at least 6 months at 4 degrees C.

[The development of a coagglutination reaction using staphylococcal peptidoglycan for the diagnosis of staphylococcal infection]. / Razrobka reaktsiï koahliutynatsiï z vykorystanniam stafilokokovoho peptydohlikanu dlia diahnostyky stafilokokovoï infektsiï.

Our objective in this study was to develop and assess the diagnostic value of a coagglutination test with making use of peptidoglycane of Staphylococcus aureus in the identification of diseases of staphylococcal etiology. A total of 166 patients with diseases of staphylococcal etiology were examined. A test was elaborated of coagglutination with making use of peptidoglycane of Staphylococcus aureus for a differential identification of antibodies to peptidoglycan in healthy persons and patients with staphylococcosis.

[The rapid identification of bacteria by agglutination on a slide of antibody-sensitized erythrocytes]. / Uskorennaia identifikatsiia bakterii aggliutinatsiei na stekle éritrotsitov, sensibilizirovannykh antitelami.

The method for the identification of Brucella (genus) and shigellae (species) by using slide agglutination of antibody erythrocytic immune reagents is substantiated. Such reagents, obtained from polyclonal nonadsorbed immune sera, ensure high specificity of taxon identification. The use of the proposed method may greatly accelerate bacteriological analysis.

Macroscopic agglutination test for rapid diagnosis of human leptospirosis.

A commercially available slide agglutination test (SAT) for the diagnosis of human leptospirosis was evaluated by comparing it to an immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) and to the microscopic agglutination test (MAT). For all 108 patients, leptospirosis was diagnosed on the basis of a fourfold or greater increase in titer by MAT (seroconversion), and all but 1 of 245 controls were MAT negative (titers, <1:100). Both SAT and the IgM ELISA failed to detect one case of infection (sensitivity, 99%). Only 3 of 145 blood donors and none of the 100 patients with other illnesses were SAT positive (specificity, 99%). The overall results were similar for the three tests; however, SAT and ELISA were statistically more sensitive as initial screening tests. For 22% of the patients, the diagnosis of leptospirosis was made earlier by SAT than by MAT. SAT detected 27 (44%) of 62 MAT-negative patients with the first serum sample. ELISA and SAT had very similar results. Follow-up of patients for 1 year after the onset of symptoms showed a decreasing rate of positivity by SAT from the third month on. The rate of positivity by ELISA decreased more slowly, to about 67% by the end of the study. By MAT all patients were persistently reactive. SAT and ELISA seem to be convenient methods for the rapid and early screening for leptospirosis and could replace the less sensitive MAT. ELISA gives less subjective results than SAT and provides information on IgM kinetics, but it can be performed only by the more sophisticated laboratories. SAT is inexpensive, can be performed more quickly and more easily than ELISA, and could be used by the less well equipped laboratories.