Detection of Chlamydia trachomatis in genitourinary medicine clinic attendees: comparison of strand displacement amplification and the ligase chain reaction.

Nucleic acid amplification (NAA) methods for the diagnosis of genital Chlamydia trachomatis infection perform well but are technically demanding. Strand displacement amplification (SDA) assay is a new NAA method that offers technical simplicity but its comparative diagnostic performance is unknown. Here, we compare the diagnostic performance of ligase chain reaction with that of SDA in first-catch urine (FCU) samples from both male and female patients and in endocervical swab (ECS) specimens. Attendees (715 men, 291 women) of a city-centre genitourinary medicine clinic were studied. FCU specimens were collected from all the men and from 205 of the women in the study. Two ECS specimens were collected from each of the women. Discordant results were resolved using an in-house nested polymerase chain reaction technique. Samples positive in two out of the three assays were considered positive. Prevalence of C. trachomatis infection was 9.2% and 9.1% in the men and women, respectively. Sensitivity, specificity, positive predictive value and negative predictive value of SDA in FCU specimens from the men were 95.5%, 100%, 100% and 99.5%, respectively. In the female group, the figures for FCU and ECS specimens were 77.3%, 100%, 100% and 97.3%, and 90.9%, 100%, 100% and 97.3%, respectively. In this high-prevalence population, SDA assay is an effective method for the detection of C. trachomatis in FCU specimens in men and in ECS (but not FCU) specimens in women. Further studies in lower-prevalence populations are required.

Comparison of enhanced chemiluminescence and microparticle enzyme immunoassay for the measurement of hepatitis B surface antibody.

Two commercially available immunoassays for the quantitative measurement of antibodies to hepatitis B surface antigen (HBsAg) were compared. The Amerlite enhanced chemiluminescence assay (ECL), which utilizes capture antigen obtained from HBsAg-positive donors bound to microtitre wells, was compared with the Abbott Laboratories microparticle enzyme immunoassay (IMx), which uses a recombinant antigen coated on to microparticle carriers. A total of 310 specimens, 116 from naturally infected patients (group A), 93 from patients vaccinated with a human plasma-derived vaccine (group B) and 101 patients vaccinated with a recombinant vaccine (group C), were tested in both assays undiluted and diluted 1:11. Samples that showed discordant results were also tested in a conventional quantitative enzyme immunoassay (Sorin). The results show significant differences in the level of anti-HBsAg in patient sera using the two technologies. In general, IMx gave significantly higher values than ECL for all three patient categories tested. These differences may lead to conflicting reports being issued by laboratories who change their assay system or when a sample from one patient is tested by different laboratories using different assays.

Antibody to Coxsackie B virus in diagnosing postviral fatigue syndrome.

OBJECTIVE: To study the association between coxsackie B virus infection and the postviral fatigue syndrome and to assess the immunological abnormalities associated with the syndrome. DESIGN: Case-control study of patients with the postviral fatigue syndrome referred by local general practitioners over one year. SETTING: General practitioner referrals in Dunbartonshire, Scotland. PATIENTS: 254 Patients referred with the postviral fatigue syndrome (exhaustion, myalgia, and other symptoms referable to postviral fatigue syndrome of fairly recent onset--that is, several months) and age and sex matched controls obtained from same general practitioner; 11 patients were rejected because of wrong diagnoses, resolution of symptoms, and refusal to participate, leaving 243 patients and matched controls. MAIN OUTCOME MEASURES: Detailed questionnaire (patients and controls) and clinical examination (patients) and blind analysis of blood sample at entry and after six months for determination of coxsackie B virus IgM and IgG antibodies and other variables (including lymphocyte protein synthesis, lymphocyte subsets, and immune complexes). RESULTS: Percentage positive rates for coxsackie B virus IgM at entry were 24.4% for patients and 22.6% for controls and for coxsackie B virus IgG 56.2% and 55.3% respectively; there were no significant differences between different categories of patients according to clinical likelihood of the syndrome nor any predictive value in a fourfold rise or fall in the coxsackie B virus IgG titre in patients between entry and review at six months. The rates of positive antibody test results in patients and controls showed a strong seasonal variation. Of the numerous immunological tests performed, only a few detected significant abnormalities; in particular the mean value for immune complex concentration was much higher in 35 patients and 35 controls compared with the normal range and mean value for total IgM was also raised in 227 patients and 35 controls compared with the normal range. CONCLUSIONS: Serological tests available for detecting coxsackie B virus antibodies do not help diagnose the postviral fatigue syndrome. Percentage positive rates of the antibodies in patients simply reflect the background in the population as probably do the raised concentrations of total IgM and immune complexes.

Myalgic encephalomyelitis--a persistent enteroviral infection?

Myalgic encephalomyelitis is a common disability but frequently misinterpreted. Amongst 6,000 patients referred for general microbiological diagnosis between 1975 and 1987, 420 cases were recognized. Coxsackie B neutralization tests, in 205 of these, demonstrated significant titres in 103/205 (50%), while of 124 additionally investigated for enteroviral IgM, 38/124 (31%) were positive. This illness is distinguished from a variety of other post-viral states by an unique clinical and epidemiological pattern characteristic of enteroviral infection. Prompt recognition and advice to avoid over-exertion is mandatory. Routine diagnosis, specific therapy and prevention, await further technical advances.

Features of Coxsackie B virus (CBV) infection in children with prolonged physical and psychological morbidity.

A retrospective study of the clinical features in 39 children who were investigated for evidence of Coxsackie B virus (CBV) infection is reported. Eighteen children were found to have serological evidence of infection. An extensive range of features was elicited in both seropositive and seronegative patients, most children complaining of abnormalities referable to muscle and, in particular, of weakness and easy fatiguability. Children with evidence of CBV infection were significantly more likely to belong to social classes I and II, to have relatives with serological evidence of CBV infection, and to show certain dysphoric features as well as to complain of sore throats. The relationship between CBV infection and 'myalgic encephalomyelitis' or 'post-viral syndrome' is discussed, and it is suggested that these descriptions are inappropriate given our current knowledge, and inadequately describe the clinical features seen in the children under study. An alternative description, 'fatigue-dysphoria syndrome' is proposed.

Coxsackie B viruses and myalgic encephalomyelitis.

Data collected over the past 6 years suggest that Coxsackie B viruses (CBV) play an important role in myalgic encephalomyelitis (ME). Since psychological upset is a feature of this illness, 247 patients, recently admitted to a psychiatric hospital, were tested for neutralizing antibodies to CBV. A total of 12.5% had significantly raised CBV titres compared with 4-5% of 'well' control groups; the percentage positive was greatest (21%) in those aged 30-39 years. During 1985 and 1986 sera from 290 adults with ME were tested using the newly developed CBV IgM ELISA test; 37% were CBV IgM positive compared with 9% of 500 'well' adult controls. Forty-seven children, with ME were similarly tested during this period; 38% were positive, implying recent or active CBV infection. The combined use of this ELISA test and the virus probe techniques now available should further help to elucidate the exact role of CBV in this disabling illness.

Chronic enterovirus infection in patients with postviral fatigue syndrome.

76 patients with the postviral fatigue syndrome (PVFS) and 30 matched controls were investigated. Virus isolation was attempted from concentrated faecal samples by direct culture and after acid dissociation of virus from antibody. Positive cultures of enteroviruses were obtained from 17 (22%) patients and 2 (7%) controls. An enterovirus-group-specific monoclonal antibody, 5-D8/1, directed against the VP1 polypeptide, was used to detect enteroviral antigen in the circulation, either free or complexed with antibody. VP1 antigen was detected in the serum of 44 (51%) of a further group of 87 PVFS patients. The number of patients positive for VP1 antigen was greater (42/44) when IgM complexes were detectable than when they were not (2/23). 1 year later, the 17 patients of the first group of 76 with positive cultures were again studied. The same virus was again isolated from 5 (29%), 13 (76%) had detectable IgM responses to enteroviruses, and 9 (53%) were positive for VP1 antigen in the serum. These results show that chronic infection with enteroviruses occurs in many PVFS patients and that detection of enterovirus antigen in the serum is a sensitive and satisfactory method for investigating infection in these patients.

Coxsackie B viruses and the post-viral syndrome: a prospective study in general practice.

In a prospective study sera from 140 patients with symptoms suggesting a post-viral syndrome and sera from 100 controls were tested for neutralizing antibodies to Coxsackie B viruses. Sixty-five of the patients (46%) and 25 of the controls (25%) had significant antibody titres. The 65 positive cases who had presented with symptoms were followed up and retested six months later and again after one year. Of these 65 patients 36 (55%) were still unwell after one year and high antibody titres persisted in all but two of the patients. Recovery was not found to correlate with a fall in antibody level, but was more rapid in patients whose presenting symptoms were paraesthesiae, anorexia or dyspnoea. The importance of correctly identifying patients with the post-viral syndrome, who may otherwise be labelled neurotic, is emphasized.

Routine use of mu-antibody-capture ELISA for the serological diagnosis of Coxsackie B virus infections.

The role of coxsackie B viruses (CBV) in myo/pericarditis has been well documented; however, interpretation of static high neutralising antibody titres in individual patients has always been difficult. In introducing the mu-antibody capture ELISA test for the detection of CBV-specific IgM, we hoped to overcome this problem. A regimen for the routine serological diagnosis of CBV infections was introduced, using the CBV IgM ELISA as a screening test, followed by neutralisation tests (NT) to confirm the positive results. Seven hundred and sixty patients and 304 healthy adult controls were tested. The percentage CBV IgM positive in each of the clinical categories myo/pericarditis (33%) chest pain (22%), myalgic encephalomyelitis (31%), myalgia/Bornholm (19%) and controls (9%) was similar to those found in previous studies using NT alone. Cross-reactions with other enteroviruses, including hepatitis A (Enterovirus 72), were observed but did not prove to be a problem in the illness studied, since most involved adults. Both homotypic and heterotypic CBV IgM responses were found. Matching IgM and NT indicated a recent CBV infection. Positive IgM with negative NT titres suggested a recent infection with an enterovirus other than a CBV.

Mu-antibody capture ELISA for the rapid diagnosis of enterovirus infections in patients with aseptic meningitis.

Between August and November 1985, 45 patients with suspected aseptic meningitis were investigated using conventional virus isolation procedures and the mu-antibody capture Coxsackie B IgM enzyme-linked immunoabsorbent assay (ELISA) test, which is well known to cross-react with other members of the enterovirus group. An enterovirus was isolated from 22% of patients compared with 67% who were positive in the ELISA test. Not only was the rate of enterovirus detection increased by using this ELISA method, the clinician received a result within 2 days of submission of serum to the laboratory. A positive result was reassuring to the patient and helpful in clinical management. The main disadvantage of this test was its cost since Coxsackie B1-5 virus antigens were essential. Development of a single inexpensive enterovirus-specific antigen is thus desirable.

A study of Coxsackie B virus infections, 1972-1983.

The results of a twelve-year study of Coxsackie B virus (CBV) infections in patients with a variety of acute and chronic illnesses are reported. CBVs were isolated from only 123 patients most of whom were children with respiratory illness. Virus diagnosis in adults was based mainly on the detection of significant rising or static high neutralizing antibody titres. Between 1972 and 1979 most investigations centred on patients with suspected viral heart disease, 12% of whom were found to have diagnostically significant CBV titres. In studies on patients with definite myo-pericarditis the number positive increased to 33%. In 1980 clinical interest switched to the possible role of CBV in myalgic encephalomyelitis (ME), an illness of diverse symptomatology. Investigation of suspected cases of ME in 1983 showed that 16% were serologically positive compared to 4% of normal adults in the West of Scotland. In patients with well-documented ME this figure rose to 41%. The demand by clinicians for CBV neutralizing antibody tests has increased over the past twelve years and continues to escalate annually, especially in patients with chronic relapsing illness.