A nested-PCR with an Internal Amplification Control for the detection and differentiation of Bartonella henselae and B. clarridgeiae: an examination of cats in Trinidad

BACKGROUND: Bartonella species are bacterial blood parasites of animals capable of causing disease in both animals and man. Cat-Scratch Disease (CSD) in humans is caused mainly by Bartonella henselae and is acquired from the cat, which serves as a reservoir for the bacteria. A second species, B. clarridgeiae is also implicated in the disease. Diagnosis of Bartonellosis by culture requires a week or more of incubation on enriched media containing blood, and recovery is often complicated by faster growing contaminating bacteria and fungi. PCR has been explored as an alternative to culture for both the detection and species identification of Bartonella, however sensitivity problems have been reported and false negative reactions due to blood inhibitors have not generally been addressed in test design. METHODS: A novel, nested-PCR was designed for the detection of Bartonella henselae and B. clarridgeiae based on the strategy of targeting species-specific size differences in the 16S-23S rDNA intergenic regions. An Internal Amplification Control was used for detecting PCR inhibition. The nested-PCR was utilized in a study on 103 blood samples from pet and stray cats in Trinidad. RESULTS: None of the samples were positive by primary PCR, but the Nested-PCR detected Bartonella in 32/103 (31%) cats where 16 were infected with only B. henselae, 13 with only B. clarridgeiae and 3 with both species. Of 22 stray cats housed at an animal shelter, 13 (59%) were positive for either or both species, supporting the reported increased incidence of Bartonella among feral cats. CONCLUSION: The usefulness of a single PCR for the detection of Bartonella henselae and B. clarridgeiae in the blood of cats is questionable. A nested-PCR offers increased sensitivity over a primary PCR and should be evaluated with currently used methods for the routine detection and speciation of Bartonella henselae and B. clarridgeiae. In Trinidad, B. henselae and B. clarridgeiae are the predominant species in cats and infection appears highest with stray cats, however B. clarridgeiae may be present at levels similar to that of B. henselae in the pet population.

Fourth-generation enzyme-linked immunosorbent assay for the simultaneous detection of human immunodeficiency virus antigen and antibody

The VIDAS HIV DUO Ultra, a fourth-generation immunoassay under development for the simultaneous detection of human immunodeficiency virus type 1 (HIV-1) p24 antigen and antibodies to HIV-1 and HIV-2, was evaluated. The enzyme-linked fluorescence immunoassay, performed on the automated VIDAS instrument, is claimed to detect early and established HIV infection. The assay was challenged with a total of 2,847 samples that included 74 members of 10 seroconversion panels, 9 p24 antigen-only-reactive members of a panel of group M clades, 503 consecutively collected samples from individuals seeking care in the University of Maryland Medical System, 1,010 samples from U.S. blood donors, 1,141 samples from patients in a high-incidence population in Trinidad, 83 samples from a clinic for sexually transmitted diseases in the Bahamas, 10 confirmed HIV-1 group O samples, and 16 confirmed HIV-2 samples from the Cote d'Ivoire. Reference tests were U.S. Food and Drug Administration-licensed HIV antibody screening, p24 antigen tests, HIV confirmatory assays, and the Roche Diagnostics Amplicor HIV-1 Monitor. The VIDAS HIV DUO Ultra demonstrated 100% sensitivity and 99.5% specificity overall, with a 99.7% specificity in low-risk individuals. The analytical sensitivity, as assessed by seroconversion panels and p24 antigen in samples, was equivalent to the sensitivity of the reference assays used to characterize these panels. The VIDAS HIV DUO Ultra is accurate, offers potential advantages over conventional HIV testing for time and cost savings, has walk-away capability, and correctly identifies both early and established HIV infections.

The role of labelled red blood cell scintigraphy in the detention of acute gastrointestinal bleeding

This paper describes the experience with 99m Technetium labelled red blood cell (99mTc RBC) scintigraphy in twenty-two patients presenting with acute gastrointestinal (GI) tract bleeding. Studies were postitive in thirteen cases - eight from the lower GI tract and five from the upper. The data from surgical intervention were available in ten cases. Scintigraphy cannot diagnose the cause of GI bleeding, as it is a nonspecific study. Its usefulness lies in its ability to accurately diagnose the bleeding site, as was shown in this study where there was good surgical correlation. The simplicity, reproducibility and reliability of the technique, particularly when bleeding rates are low and intermittent, make it, in our view, the first line of investigation in any patient with suspected bleeding from the colon or upper GI tract if endoscopic evaluation is not possible in the latter. Its current under-utilisation in the Caribbean may be a reflection of the lack of nuclear imaging facilities.(Au)

Assessment of the efficacy of an IgM-elisa and microscopic agglutination test (MAT) in the diagnosis of acute leptospirosis

In a prospective study in Barbados between 1979 and 1989, 321 cases were diagnosed in 638 patients presenting at a hospital with symptoms of leptospirosis. Initial diagnosis was based on patient history and characteristic signs and symptoms. In 92 cases (29 percent), diagnosis was confirmed by isolation of organisms from the blood, urine, or dialysate fluid; in the remaining 229 cases (71 percent) diagnosis was confirmed by serology alone. Results of an IgM-ELISA and microscopic agglutination test (MAT) in cases with isolates and in non-specificity of the tests. The sensitivity of IgM detection by ELISA was 52 percent in the first acute-phase specimen, increasing to 89 percent and 93 percent in the second acute-phase specimen, increasing specimens respectively. The specificity of the IgM-ELISA was high (> or =94 percent) in all specimens. The sensitivity of the MAT was low (30 percent) in the first acute-phase specimen, increasing to 63 percent in the second acute-phase specimen and 76 percent in the convalescent specimen. The specificity of the MAT was > or = 97 percent in all specimens. (AU)

Heavy metals, lipid peroxidation, and ciguatera toxicity in the liver of the Caribbean barracuda (Sphyraena barracuda)

Human consumption of over 400 species of tropical fish containing polyether toxins (e.g. ciguatoxins, maitotoxins) causes ciguatera fish poisoning. The Caribbean barracuda (Sphyraena barracuda) is one of the most potent ciguatoxic fish. The objective of this study was to determine whether toxicity of 14 barracuda livers was correlated with lipid peroxidation. A significant correlation (p = 0.015, Pearson's correlation) between lipid peroxidation and toxicity of barracuda liver was found. Because iron and copper are well-known catalysts of hydroxyl radical production and lipid peroxidation in biological systems, the correlation between the concentrations of these metals in barracuda liver and lipid peroxidation and toxicity was also investigated. Cadmium was significantly correlated (p = 0.014) with the toxicity of barracuda livers. This study provides the first data concerning the concentration of iron, copper, and cadmium in the liver of the Caribbean barracuda. Of the three metals studied in barracuda liver, iron was the most abundant, followed by copper and cadmium. Lipid peroxidation was highly variable and detected in five (36 percent) of the liver samples. Lipid peroxidation was not statistically significantly correlated (p > 0.05) with concentrations of iron, copper, and cadmium in barracuda liver. Collectively, these findings provide additional evidence that lipid peroxidation can be a mechanistic component of ciguatera toxicity in the Caribbean barracuda.(Au)

Genital ulcers: etiology, clinical diagnosis, and associated human immunodeficiency virus infection in Kingston, Jamaica

Individuals presenting consecutively with genital ulcers in Kingston, Jamaica, underwent serological testing for human immunodeficiency virus (HIV) infection , chlamydial infection, and syphilis. Ulcer material was analyzed by the multiplex polymerase chain reaction (M-PCR) analysis DNA from herpes simplex virus (HSV), Haemophilus ducreyi, and Treponema pallidum was detected in 158 (52.0 percent), 72 (23.7 percent), and 31 (10.2 percent) of 304 ulcer specimens. Of the 304 subjects, 67 (22 percent) were HIV-seropositive and 64 (21 percent) were T. pallidum-seroactive. Granuloma inguinale was clinically diagnosed in nine (13.4 percent) of 67 ulcers negative by M-PCR analysis and in 12 (5.1 percent) of 237 ulcers positive by M-PCR analysis (P = .03). Lymphogranuloma venereum was clinically diagnosed in eight patients. Compared with M-PCR analysis, the sensitivity and specificity of a clinical diagnosis of syphilis, herpes, and chancroid were 67.7 percent, 53.8 percent, and 75 percent and 91.2 percent, 83.6 percent, and 75.4 percent, respectively. Reactive syphilis serology was 74 percent sensitive and 85 percent specific compared with M-PCR analysis. Reported contact with a prostitute in the preceding 3 months was associated with chancroid (P = .009), reactive syphilis serology (P = .011), and HIV infection (P = .007). The relatively poor pleads for syndromic management of genital ulcers in Jamaica. Prevention efforts should be intensified.(Au)

Prospective evaluation of enzyme-linked immunosorbent assay and immunoblot methods for the diagnosis of endemic Strongyloides stercoralis infection

Recently described enzyme-linked immunosorbent assay (ELISA) and immunoblot methods for the detection of serum IgG against Strongyloides stercoralis larval antigens were prospectively evaluated for the diagnosis of endemic strongyloidiasis. A modification of the ELISA involved preincubation of sera with Onchocerca gutturosa phosphate-buffered saline-soluble extract to remove cross-reactivity with other helminths. The sensitivity of the ELISA increased from 80 percent and 85 percent following preincubation. Similarly, there was an increase in specifity from 94 percent to 97 percent. The IgG recognition of 41-, 31-, and 28-kD filariform larval components showed sensitivities of 100 percent, 85 percent and 65 percent, respectively. Both the ELISA following incubation of sera with O. gutturosa extract and serum IgG reactivity to a 41-kD larval component using immunoblotting are sensitive and specific techniques for diagnosing endemic strongyloidiasis.(AU)

Assessment of risk of perinatal death in Jamaica

Data from the Jamaican Perinatal Mortality Survey had been used to create a statistical model using logistic regression. From this a simple additive scoring system to predict perinatal death was devised and tested on the 2 cohort months of the study. The score had a theoretical range of 0-28 points, with the higher the score, the greater the likelihood of a perinatal death. For a cut-point of 7 sensitivity was 43 percent and specificity 84 percent. A cut-point of 8 resulted in 27 percent sensitivity and 94 percent specificity. Higher cut-points resulted in much reduced sensitivity but enhanced specificity (e.g. cut-point 10: 11 percent sensitivity, 99 percent specificity). However, it is likely that these estimates are optimistically high, and to achieve unbiased estimates of sensitivity and specificity the score needs to be tested on a sample of the population from which it was not derived before implementation takes place. Meanwhile, the cut-off level for implementation will depend on appropriate resources available (Summary)

Difficulties in assessing drug/food interactions from chart audit in an elderly Barbadian sample group

The aim of this study was to examine the prevalence of potential drug/food interactions among 290 elderly Barbadian outpatients. These findings indicate that chart audit is insensitive to definite interactions but was able to detect the prevalence of potential interactions (1.38 per outpatient). The risk of potential interaction was significantly higher among outpatients who were older, female, and those who used a larger number of prescribed medications. There were no significant differences in the prevalence of potential interactions among diabetics and nondiabetics. The findings indicate that the absence of relevant data on patients'symptoms, and anthropometric and laboratory measures in more than 80 percent of patients' charts makes it impossible to assess the prevalence of definite drug/food interactions from chart audit. Weight changes, nutrient levels, and symptoms were the most frequently missing data. Chart audit is therefore an invalid and unreliavle approach to estimate definite drug/food medications (AU)

Serum IgG reactivity with 41-, 31- and 28-kDa larval proteins of Strongyloides stercoralis in individuals with strongyloidiasis

Proteins from a deoxycholate-soluble extract of Strongyloides stercoralis infective larvae were separated by SDS-PAGE, blotting onto nitrocellulose paper, and reacted with sera from individuals with confirmed S. stercoralis infections (n = 100), suspectedS. stercoralis infections in whom no larvae could be detected (n = 27), and other nematode infections (40 with Wuchereria bancrofti, 20 with Onchocerca volvulus, 20 with Necator americanus, and 20 with mixed Ascaris lumbricoides and Trichuris trichiura infections). Immunodominant proteins of approximately 41, 31, and 28 kDa were recongnized by IgG in 91 percent, 88 percent and 90 percent respectively, of sera from those with confirmed strongyloidiasis; in 100 percent, 100 percent, and 93 percent of sera from those with suspected strongyloidiasis; and in 9 percent, 12 percent and 14 percent of sera from those infected with other nematodes. IgG reactivity to each of these proteins was a more specific means of immunodiagnosis than the currently use indirect ELISA; the methods were equally sensitive.(AU)

Reported versus recorded health service utilization in Grenada, West Indies

Calls for household surveys to provide information on service utilization in less developed countries raise questions regarding the accuracy and reliability of reporting. This paper compares reported to recorded health service utilization for diarrhoea and any other morbidity over a 2-week and 3-month period for information obtained from a household survey in Grenada, West Indies. A sensitivity analysis is used to derive minimum and maximum estimates of the accuracy of reported utilization. Over-reporting utilization was found to be between 33 and 62 percent for diarrhoea and 49 and 81 percent for any other morbidity. Under-reporting of all utilization was estimated to be between 47 and 65 percent. These results cast doubt on the utility of household surveys as a reliable source of information regarding service utilization. (AU)