Coxiella burnetii (Q fever) seroprevalence in cattle.

Human cases of Q fever appear to be common in Northern Ireland compared to the rest of the British Isles. The purpose of this study was to describe the seroepidemiology of Coxiella burnetii infection in cattle in Northern Ireland in terms of seroprevalence and determinants of infection. A total of 5182 animals (from a stratified systematic random sample of 273 herds) were tested with a commercial C. burnetii phase 2 IgG ELISA. A total of 6.2% of animals and 48.4% of herds tested positively. Results from a multilevel logistic regression model indicated that the odds of cattle being infected with Q fever increased with age, Friesian breed, being from large herds and from dairy herds. Large dairy herd animal prevalence was 12.5% compared to 2.1% for small beef herds. Preliminary seroprevalence in sheep (12.3%), goats (9.3%), pigs (0%) rats (9.7%) and mice (3.2%) using indirect immunofluorescence is reported.

Comparison of serum and whole-blood specimens for the detection of Candida DNA in critically ill, non-neutropenic patients.

In contrast to the multitude of studies on fungal PCR assay methods, little work has been reported evaluating Candida PCR performance when using whole blood compared with serum in candidaemic patients. Here, a comparison of the performance of whole-blood and serum specimens using a set of real-time PCR Candida species assays is described. Specimens were collected prospectively from non-neutropenic adults who were recruited to a diagnostic clinical trial, the primary purpose of which was to verify the performance of the assays using serum; in all, 104 participants also had whole-blood specimens submitted for analysis in addition to the serum specimen. Of these participants, 10 had laboratory-confirmed candidaemia and 94 were categorized as being 'unlikely' to have invasive Candida infection. PCR results from the whole-blood specimens are presented here and compared with the results from serum specimens in this subgroup among whom both specimen types were obtained contemporaneously. All participants with candidaemia were PCR-positive from serum samples; however, only seven were PCR-positive from whole blood. All specimens from patients in the 'unlikely' category were PCR-negative in both types of specimen. Moreover, DNA extraction from serum required 1 h; extraction from whole blood required approximately 3 h. These data tentatively suggest that, overall, serum is an appropriate specimen for Candida PCR for detection of candidaemia in non-neutropenic adults.

Human seroprevalence to Coxiella burnetii (Q fever) in Northern Ireland.

Despite the widespread prevalence of infection with Coxiella burnetii, there have been few large population-based studies examining the epidemiology of this infection. The aim of this study was to examine the distribution and determinants of C. burnetii past infection in Northern Ireland (NI). Coxiella burnetii phase II specific IgG antibodies were measured by enzyme-linked immunosorbent assay in stored serum from 2,394 randomly selected subjects, aged 12-64, who had participated in population-based surveys of cardiovascular risk factors performed in 1986 and 1987. The overall prevalence of C. burnetii antibody positivity was 12.8%. The prevalence of sero-positivity was slightly higher in males than that in females (14.3% versus 11.2%, P = 0.02). Sero-positivity was low in children (<10%), increasing to 19.5% and 16.4% in males and females, respectively, in the 25-34 age group and subsequently remaining fairly steady with increasing age. Sero-positivity among farmers, at 48.8%, was significantly higher than the general population. More sero-positive than sero-negative women had a history of a miscarriage or still-birth (19.5% versus 9.8%, P < 0.001). In conclusion, this study demonstrated a high prevalence of evidence of past C. burnetii infection in NI. Associations between past C. burnetii infection and age, sex, social class, occupation and reproductive history were seen. We estimate that 20% of Q fever infections in NI occur in farmers.

A prospective clinical trial of a real-time polymerase chain reaction assay for the diagnosis of candidemia in nonneutropenic, critically ill adults.

BACKGROUND: Invasive Candida infection among nonneutropenic, critically ill adults is a clinical problem that has received increasing attention in recent years. Poor performance of extant diagnostic modalities has promoted risk-based, preemptive prescribing in view of the poor outcomes associated with inadequate or delayed antifungal therapy; this risks unnecessary overtreatment. A rapid, reliable diagnostic test could have a substantial impact on therapeutic practice in this patient population. METHODS: Three TaqMan-based real-time polymerase chain reaction assays were developed that are capable of detecting the main medically important Candida species, categorized according to the likelihood of fluconazole susceptibility. Assay 1 detected Candida albicans, Candida parapsilosis, Candida tropicalis, and Candida dubliniensis. Assays 2 and 3 detected Candida glabrata and Candida krusei, respectively. The clinical performance of these assays, applied to serum, was evaluated in a prospective trial of nonneutropenic adults in a single intensive care unit. RESULTS: In all, 527 specimens were obtained from 157 participants. All 3 assays were run in parallel for each specimen; they could be completed within 1 working day. Of these, 23 specimens were obtained from 23 participants categorized as having proven Candida infection at the time of sampling. If a single episode of Candida famata candidemia was excluded, the estimated clinical sensitivity, specificity, and positive and negative predictive values of the assays in this trial were 90.9%, 100%, 100% and 99.8%, respectively. CONCLUSIONS: These data suggest that the described assays perform well in this population for enhancing the diagnosis of candidemia. The extent to which they may affect clinical outcomes, prescribing practice, and cost-effectiveness of care remains to be ascertained.

High levels of Epstein-Barr virus in COPD.

Latent viral infection has been implicated in the pathophysiology of chronic obstructive pulmonary disease (COPD). Epstein-Barr virus (EBV) is known to be important in pulmonary fibrosis. The current authors hypothesised that EBV is associated with the pathogenesis of COPD. Sputum samples were collected from patients both during exacerbations of COPD and when stable. A control group of smokers who did not have airways obstruction also had their sputum examined. The presence of EBV DNA was established and quantified using a real-time nucleic acid amplification assay. A total of 136 patients with COPD were recruited during an acute exacerbation and a total of 68 when stable. EBV was detected in 65 (48%) exacerbation cases and 31 (46%) stable patients. In the comparison group of 16 nonobstructed smokers, EBV was demonstrated in only one (6%) case. Risk of COPD in patients with EBV and who are smokers confers an odds ratio of 12.6. Epstein-Barr virus DNA is more frequently identified in the respiratory tract of chronic obstructive pulmonary disease patients in comparison with unaffected smokers. It is present both during exacerbation and when stable, suggesting that infection is persistent. Smokers who do not develop chronic obstructive pulmonary disease rarely have Epstein-Barr virus in their sputum. This finding may be of importance in the pathogenesis of chronic obstructive pulmonary disease.

Improving molecular detection of Candida DNA in whole blood: comparison of seven fungal DNA extraction protocols using real-time PCR.

The limitations of classical diagnostic methods for invasive Candida infections have led to the development of molecular techniques such as real-time PCR to improve diagnosis. However, the detection of low titres of Candida DNA in blood from patients with candidaemia requires the use of extraction methods that efficiently lyse yeast cells and recover small amounts of DNA suitable for amplification. In this study, a Candida-specific real-time PCR assay was used to detect Candida albicans DNA in inoculated whole blood specimens extracted using seven different extraction protocols. The yield and quality of total nucleic acids were estimated using UV absorbance, and specific recovery of C. albicans genomic DNA was estimated quantitatively in comparison with a reference (Qiagen kit/lyticase) method currently in use in our laboratory. The extraction protocols were also compared with respect to sensitivity, cost and time required for completion. The TaqMan PCR assay used to amplify the DNA extracts achieved high levels of specificity, sensitivity and reproducibility. Of the seven extraction protocols evaluated, only the MasterPure yeast DNA extraction reagent kit gave significantly higher total nucleic acid yields than the reference method, although nucleic acid purity was highest using either the reference or YeaStar genomic DNA kit methods. More importantly, the YeaStar method enabled C. albicans DNA to be detected with highest sensitivity over the entire range of copy numbers evaluated, and appears to be an optimal method for extracting Candida DNA from whole blood.

Trends in candidemia and antifungal susceptibility in a university hospital in Northern Ireland 2001-2006.

OBJECTIVES: To describe the species distribution and antifungal susceptibility trends for documented episodes of candidemia at the Royal Hospitals, Belfast, 2001-2006. METHODS: Laboratory-based retrospective observational study of all episodes of candidemia. RESULTS: There were 151 episodes of candidemia. The species recovered were: 96 C. albicans; 26 C. glabrata; 18 C. parapsilosis; five C. tropicalis; four C. guilliermondii; one C. famata and one C. dubliniensis. We separated the data into two periods 2001-2003 and 2004-2006; contrary to the findings of other investigators, there was a notable trends toward increasing frequency of C. albicans and decreasing frequency of non-albicans species over time. Although the proportion of C. albicans, C. parapsilosis and C. tropicalis isolates susceptible to fluconazole was unchanged over time, a trend of decreased susceptibility of C. glabrata to fluconazole was noted over the six-year period. Overall, 73% and 7.7% of C. glabrata isolates had susceptible-dose-dependent and resistant phenotypes, respectively. The percentage of C. glabrata isolates susceptible to fluconazole (MIC <8 microg/ml) decreased from 36% in 2001-2003 to 0% in 2004-2006. Flucytosine resistance was detected in only 4 (2.7%) isolates. None of the isolates had an amphotericin B MIC <1 microg/ml. CONCLUSION: A shift towards increasing dominance of C. albicans contrasts both with reports from other countries and previous data from Northern Ireland. Upwards fluconazole MIC drift among C. glabrata has important implications for empirical therapeutic decisions.

Asymptomatic shedding of HSV-1 in patients undergoing oral surgical procedures and attending for noninvasive treatment.

Oral surgery and stress can trigger and/or increase asymptomatic shedding of herpes simplex virus type-1 (HSV-1) into human saliva. In this investigation we examined the frequency of HSV-1 shedding in 32 patients undergoing an oral surgery procedure compared with 40 control patients attending for noninvasive treatment. Control patients comprised 18 migraine patients and 22 patients with temporomandibular (TMD) joint problems. Nested-PCR was carried out on oral rinses collected from each patient prior to treatment and 7 days post-treatment. Fifty-two of sixty-one seropositive patients were positive for HSV-1 DNA in one or both oral rinses. The frequencies of HSV-1 shedding for the oral surgery and control patients were 84.6% and 85.7% respectively. Seropositive patients who started shedding after treatment were significantly higher in oral surgery patients (46.2%) compared to control patients (34.3%). Shedding of HSV-1 in the oral cavity is not only increased by direct surgical trauma, but also appears to be common in migraine and TMD patients attending for general dental treatment. Thus pain or pain-induced stress as well as anxiety associated with dental treatment may also be a risk factor for asymptomatic shedding in specific seropositive patients attending for dental treatment.

Rapid differentiation between fluconazole-sensitive and -resistant species of Candida directly from positive blood-culture bottles by real-time PCR.

In view of both the delay in obtaining identification by conventional methods following blood-culture positivity in patients with candidaemia and the close relationship between species and fluconazole (FLC) susceptibility, early speciation of positive blood cultures has the potential to influence therapeutic decisions. The aim was to develop a rapid test to differentiate FLC-resistant from FLC-sensitive Candida species. Three TaqMan-based real-time PCR assays were developed to identify up to six Candida species directly from BacT/Alert blood-culture bottles that showed yeast cells on Gram staining at the time of initial positivity. Target sequences in the rRNA gene complex were amplified, using a consensus two-step PCR protocol, to identify Candida albicans, Candida parapsilosis, Candida tropicalis, Candida dubliniensis, Candida glabrata and Candida krusei; these are the most commonly encountered Candida species in blood cultures. The first four of these (the characteristically FLC-sensitive group) were identified in a single reaction tube using one fluorescent TaqMan probe targeting 18S rRNA sequences conserved in the four species. The FLC-resistant species C. krusei and C. glabrata were detected in two further reactions, each with species-specific probes. This method was validated with clinical specimens (blood cultures) positive for yeast (n=33 sets) and the results were 100 % concordant with those of phenotypic identification carried out concomitantly. The reported assay significantly reduces the time required to identify the presence of C. glabrata and C. krusei in comparison with a conventional phenotypic method, from approximately 72 to <3 h, and consequently allows optimization of the antifungal regimen at an earlier stage.

Herpes simplex type 1 shedding is associated with reduced hospital survival in patients receiving assisted ventilation in a tertiary referral intensive care unit.

The impact of shedding of herpes simplex virus type 1 (HSV-1) on hospital survival of patients receiving assisted ventilation in an adult tertiary referral, acute trauma intensive care unit was assessed. The study was designed to address a clinical impression linking HSV-1 recovery with poor survival. Two hundred and forty-one males and 152 females were enrolled into a longitudinal cohort study. Combined throat swabs and tracheal secretions were tested for HSV-1 shedding using a nested nucleic acid amplification protocol; patients were ranked as nonshedders, shedders, and high-level shedders. Nonparametric analysis assessed the impact of shedding on hospital survival and logistic regression measured the confounding influence of sex, age, and the Acute Physiology, Age and Chronic Health Evaluation (APACHE II) score. Linear-by-linear association determined the influence of the level of shedding on hospital survival. The observed mortality rate was 113/393 (28.8%). Patients shedding HSV-1 106/393 (27%) had a significant reduction in hospital survival 66/106 (62%) in HSV-1 shedders compared with 217/287 (75.6%) in nonshedders (P = 0.002). This difference remained significant when adjusted for age and sex (P = 0.026). Respective mortality figures for HSV-1 shedders and nonshedders were 43/106 (40.6%) and 70/287 (24.4%) (P = 0.002). HSV-1 shedding was associated with a significant reduction in hospital survival amongst patients receiving assisted ventilation. Hospital mortality in HSV-1 shedders was increased by 16.2% over nonshedders. The role of HSV-1 in this setting needs to be addressed.

Emergence of herpes simplex type 1 as the main cause of recurrent genital ulcerative disease in women in Northern Ireland.

BACKGROUND: Genital herpes is a common infection affecting some 20% of sexually active people. Although herpes simplex virus (HSV) types 1 and 2 can both establish genital latency, reactivation from the sacral ganglia favours HSV-2. Over the past decade the incidence of type 1 genital infection in women has greatly increased. OBJECTIVES: To determine whether the increased prevalence of HSV-1 genital infection was benign or influencing the pattern of virus recovery in recurrent infection. STUDY DESIGN: A retrospective analysis of laboratory computer records was undertaken. Patients attending six genitourinary medicine (GUM) departments, over an 80 months period, were identified. Recurrent infection was confirmed where virus was recovered from at least two separate episodes of genital ulceration that were separated by an interval of 12 or more weeks. Episodes were further analysed for frequency, age, gender and virus type. RESULTS: Sixty nine patients with recurrent genital herpetic infection were identified. HSV-1 and HSV-2 were predominantly recovered from recurrent genital infections in females (34 HSV-1 vs. ten HSV-2) and males (one HSV-1 vs. 24 HSV-2), respectively (P>0.001). The mean age of females and males, at the initial diagnosis, was 26 and 39 years. There was no difference in the recurrence rate by type. CONCLUSIONS: HSV-1 has become the commonest cause of recurrent genital ulceration in Northern Ireland, almost entirely due its recent increased prevalence in women over the last decade. Women are experiencing genital herpetic infections at an earlier age than men.

Clinical assessment of a generic DNA amplification assay for the identification of respiratory adenovirus infections.

BACKGROUND: respiratory adenoviruses are common, often resulting in serious sporadic and epidemic infections and impaired immunity can dramatically increase their severity. They are now thought capable of establishing latency. Diagnosis by culture is slow while direct antigen detection by immunofluorescence lacks sensitivity. Molecular diagnosis can be both rapid and sensitive but the genetic heterogeneity of adenoviruses poses problems. OBJECTIVES: to design a generic adenovirus nested polymerase chain amplification assay designed to be capable of detecting all respiratory adenoviruses. This was achieved through optimised thermal cycling and the development of a generic degenerate primer set targeting the adenovirus hexon gene. STUDY DESIGN: this was a cross-sectional study on 172 respiratory specimens from hospital-based patients, and one from a general practice, in Northern Ireland. A comparison was made between the amplification assay, virus culture and immunofluorescence. RESULTS: the nested polymerase chain reaction (nPCR) assay had a generic capacity for adenovirus detection and an analytical sensitivity of 6.4x10(2) copies/ml. Using an expanded gold standard (defined as a true positive or a true negative where a specimen was positive or negative by at least two of the study assays, respectively), PCR had a clinical sensitivity and specificity of 46/46 (100%) and 15/126 (91.3%), respectively. Patients with acute respiratory adenovirus infections were more likely to be male (chi(2), p=0.005) and to present with a fever (chi(2), p=0.02) than patients diagnosed with another respiratory virus. Co-infection was identified in 12/172 patients. CONCLUSIONS: the nested amplification assay proved highly sensitive in both the analytical and clinical settings for the detection of respiratory adenovirus infections.

Clinical utility of nested multiplex RT-PCR for group F adenovirus, rotavirus and norwalk-like viruses in acute viral gastroenteritis in children and adults.

BACKGROUND: The diagnosis of viral gastroenteritis can be carried out by non-molecular techniques such as electron microscopy (EM), enzyme-immunoassay and latex agglutination tests and various molecular techniques. Normally molecular detection requires the use of three separate protocols to detect the three main causes of viral gastroenteritis, adenoviruses, rotaviruses and norwalk-like viruses (NLV) which have different types of nucleic acid. The development of a sensitive and specific assay which could detect these targets would have major advantages for the clinical virology laboratory. OBJECTIVES: The aims of the present study were to develop a sensitive and specific multiplex molecular assay and to apply it to the detection of viral agents in clinical cases of acute gastroenteritis. STUDY DESIGN: The multiplex assay was designed using Access RT-PCR (Promega). Primers were researched and selected for their specificity and broad range detection of the viral agents across the various genotypes of group A rotaviruses, NLV and group F adenoviruses. RESULTS: From September 2000 to August 2001 we tested 1945 clinical specimens. Rotavirus infections were detected in 190 with an age range from 12 days to 8 years old. Group F adenovirus was detected in 96 patients ranging from 15 days to 10 years old. A further single case of group F adenovirus was detected in an adult of 75 years old. NLVs were detected in 132 patients. There were 55 infections in children less than 7 years old. In 10 different outbreaks involving 130 adult patients there were 57 NLV positives. Sporadic NLV infection was detected in 11 of 600 adult patients. There were 4 patients with dual infections. CONCLUSIONS: The assay detailed here has proved an invaluable tool for the investigation of acute gastroenteritis in specimens from patients of all ages. We found it convenient to use a single mastermix with a single protocol to test all specimens from patients of all ages. NLV in children is often overlooked and/or under reported, particularly where less sensitive assays such as EM are being employed for diagnosis.

Clinical utility of a nested nucleic acid amplification format in comparison to viral culture for the diagnosis of mucosal herpes simplex infection in a genitourinary medicine setting.

BACKGROUND: Nested nucleic acid amplification tests are often thought too sensitive or prone to generating false positive results for routine use. The current study investigated the specificity and clinical utility of a routine multiplex nested assay for mucosal herpetic infections. METHODS: Ninety patients, categorised into those clinically diagnosed to (a) have and (b) not have herpetic infection, were enrolled. Swabs from oral and ano-genital sites were assayed by the nested assay and culture and the results assessed against clinical evaluation for diagnosing herpetic infections; cell content was also recorded. RESULTS: Twenty-six and 64 patients were thought to (a) have and (b) not have mucosal herpetic infection. Taking the clinical evaluation as indicating the presence of herpetic infection, the nested polymerase chain reaction and culture had respective sensitivities of 19/26 (73%) and 12/26 (46%) (Chi2 p = 0.02). There was no significant difference in specificities between nPCR62/64 (97%) and culture 63/64 (98%) (Chi2 p = 1.0). Cell content was important for viral detection by nPCR (Chi2 p = 0.07) but not culture. Nesting was found necessary for sensitivity and did not reduce specificity. Assay under-performance appeared related to sub-optimal cell content (20%) but may have reflected clinical over-diagnosis. The results suggest the need for validating specimen cell quality. CONCLUSIONS: This study questions the value of routine laboratory confirmation of mucosal herpetic infection. The adoption of a more discriminatory usage of laboratory diagnostic facilities for genital herpetic infection, taking account of cell content, and restricting it to those cases where it actually affects patient management, may be warranted.

Non-detection of Chlamydia species in carotid atheroma using generic primers by nested PCR in a population with a high prevalence of Chlamydia pneumoniae antibody.

BACKGROUND: The association of Chlamydia pneumoniae with atherosclerosis is controversial. We investigated the presence of C. pneumoniae and other Chlamydia spp. in atheromatous carotid artery tissue. METHODS: Forty elective carotid endarterectomy patients were recruited (27 males, mean age 65 and 13 females mean age 68), 4 had bilateral carotid endarterectomies (n= 44 endarterectomy specimens). Control specimens were taken from macroscopically normal carotid artery adjacent to the atheromatous lesions (internal controls), except in 8 cases where normal carotid arteries from post mortem (external controls) were used. Three case-control pairs were excluded when the HLA DRB gene failed to amplify from the DNA. Genus specific primers to the major outer membrane protein (MOMP) gene were used in a nested polymerase chain reaction (nPCR) in 41 atheromatous carotid specimens and paired controls. PCR inhibition was monitored by spiking with target C. trachomatis. Atheroma severity was graded histologically. Plasma samples were tested by microimmunofluorescence (MIF) for antibodies to C. pneumoniae, C. trachomatis and C. psittaci and the corresponding white cells were tested for Chlamydia spp. by nPCR. RESULTS: C. pneumoniae was not detected in any carotid specimen. Twenty-five of 38 (66%) plasma specimens were positive for C. pneumoniae IgG, 2/38 (5%) for C. trachomatis IgG and 1/38 (3%) for C. psittaci IgG. CONCLUSIONS: We were unable to show an association between the presence of Chlamydia spp. and atheroma in carotid arteries in the presence of a high seroprevalence of C. pneumoniae antibodies in Northern Ireland.

A comparison of nested polymerase chain reaction and immunofluorescence for the diagnosis of respiratory infections in children with bronchiolitis, and the implications for a cohorting strategy.

Cohorting bronchiolitis patients infected with respiratory syncytial virus (RSV) and/or influenza viruses is paramount in preventing cross-infection of these viruses in hospital. Nested polymerase chain reaction (nPCR) was compared with immunofluorescence (IF) for the detection of RSV subtypes A and B in children with suspected bronchiolitis. Co-infection with influenza A(H3N2), Chlamydia spp. and picornavirus/rhinovirus was also investigated using molecular techniques.A total of 50 nasopharyngeal secretions collected from babies admitted with bronchiolitis in the month of January 2000, comprising IF RSV positive (N= 27) and RSV negative (N= 23) specimens, were tested for both RSV subtypes, influenza A(H3N2), Chlamydia spp. and picornavirus/rhinovirus by nPCR. Nested PCR detected 28 specimens positive for RSV (RSV A = 20, RSV B = 8), which was two more than detected by IF. Influenza A(H3N2) was detected in three specimens, Chlamydia trachomatis in one, and picornavirus in 11, of which nine were confirmed to be rhinovirus by nPCR. Dual infection was detected in five cases using nPCR. Nested PCR proved useful in detecting RSV and influenza A(H3N2) infections missed by IF, and also other respiratory tract pathogens not routinely investigated. The clinical implications and risk of cross-infection with potentially virulent viruses due to inaccurate results from insensitive techniques, highlights the need for molecular assays such as nPCR to be employed as a routine method of investigation, provided as part of the laboratory service. Cohorting of patients with clinical bronchiolitis should continue, whilst awaiting laboratory confirmation.

Gastroenteritis outbreaks associated with Norwalk-like viruses and their investigation by nested RT-PCR.

BACKGROUND: Norwalk-like viruses are the most common cause of gastroenteritis outbreaks and sporadic cases of vomiting and diarrhoea. In healthy individuals infection is often mild and short-lived but in debilitated patients infection can be severe. It is essential that the virus laboratory can offer a sensitive and specific test, delivered in a timely manner. METHODS: We have developed a nested reverse transcriptase PCR based on published primers against the RNA polymerase gene and after comparison with electronmicroscopy used the assay to investigate 31 outbreaks of gastroenteritis. These were in diverse situations including nursing homes, small district hospitals, large general hospitals, a ferry ship, hotels, restaurants and staff canteens. RESULTS: A positive diagnosis was made in 30/31 outbreaks investigated giving an overall outbreak positive detection rate of 97%. At an individual patient level there was a positive diagnostic rate of 11.5% in a large hospital environment to 100% in smaller outbreak situations. The average patient positive rate was 34%. In addition we investigated 532 control faecal specimens from adults. Of these 530 were negative and 2 were repeatedly positive. CONCLUSIONS: It is essential that insensitive electronmicroscopy is replaced with the more sensitive reverse transcription PCR assays. These tests should be made available "on call" at weekends and public holidays. It is also important that outbreaks of NLV infection are monitored using sensitive RT-PCR assays so that the laboratory information can be used in ascertaining the spread and duration of the outbreak.

A coulometric iodimetric procedure for measuring the purity of lewisite.

A new analytical method for the determination of the purity of CASARM Lewisite samples (Chemical Agent Standard Analytical Reference Materials) has been developed and tested. The method essentially replaces the volumetric iodimetric procedures currently in use with the in-situ electrochemical generation of iodine. Tests on both arsenious acid and Lewisite/CVAA solutions show that the method is capable of achieving high accuracy and precision. Sample preparation and analysis times are considerably less than the current titrimetric method. The coulometric iodimetric method has been shown capable of determining not only total organic trivalent arsenic, but also total trivalent arsenic merely by adjusting the pH. Organic arsenic is determined at pH 4, and total trivalent arsenic at pH 8.

Nested multiplex polymerase chain reaction for the diagnosis of cutaneous herpes simplex and herpes zoster infections and a comparison with electronmicroscopy.

Herpes simplex virus (HSV) and varicella zoster virus (VZV) are common causes of cutaneous and mucocutaneous vesicular eruptions. Laboratory diagnostic techniques include Tzanck smears, electronmicroscopy, antigen detection and viral culture. This paper describes a nested multiplex polymerase chain reaction with respective sensitivities of 0.0001, 0.01 and 0.1 TCID50 for VZV, HSV-1 and HSV-2. The assay was used in (a) a salvage capacity for slides already processed for electronmicroscopy, and (b) as a front-line assay for prospectively processed specimens. Sixty-two glass slides with vesicle lymph/scrapings from 58 patients with suspected cutaneous herpetic lesions were examined. The clinical presentations were described as atypical/not specified (24), VZV (20) or HSV (18), and involved eruptions from diverse anatomical sites, including the genitalia. Of the 62 specimens, 6 and 38 were positive by electronmicroscopy and multiplex PCR respectively, giving a comparative sensitivity of 16% for electronmicroscopy. Nested multiplex PCR identified 15 VZV and 20 HSV-1 infections. Where the clinical details indicated either HSV or VZV (38/62), nested multiplex PCR was statistically likely to be reactive (26/38 vs. 9/24) (chi2 P = 0.000004) whereas electronmicroscopy was not (4/38 vs. 2/24) (chi2 P= 0.77). Where the clinical details indicated VZV (20/62) or HSV (18/62), nested multiplex PCR was statistically more likely to confirm VZV (10/20 vs. 5/42) (chi2 P= 0.001) or HSV (9/18 vs. 11/44) (chi2 P = 0.05) respectively. Two suspected HSV and 6 suspected VZV infections were shown to be VZV and HSV respectively by nested multiplex PCR.