Diagnostic accuracy of a prototype rapid chlamydia and gonorrhoea recombinase polymerase amplification assay: a multicentre cross-sectional preclinical evaluation

Objectives

Rapid and accurate sexually transmitted infection diagnosis can reduce onward transmission and improve treatment efficacy. We evaluated the accuracy of a 15-minute run-time recombinase polymerase amplification–based prototype point-of-care test (TwistDx) for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG).

Methods

Prospective, multicentre study of symptomatic and asymptomatic patients attending three English sexual health clinics. Research samples provided were additional self-collected vulvovaginal swab (SCVS) (female participants) and first-catch urine (FCU) aliquot (female and male participants). Samples were processed blind to the comparator (routine clinic CT/NG nucleic acid amplification test (NAAT)) results. Discrepancies were resolved using Cepheid CT/NG GeneXpert.

Results

Both recombinase polymerase amplification and routine clinic NAAT results were available for 392 male and 395 female participants. CT positivity was 8.9% (35/392) (male FCU), 7.3% (29/395) (female FCU) and 7.1% (28/395) (SCVS). Corresponding NG positivity was 3.1% (12/392), 0.8% (3/395) and 0.8% (3/395). Specificity and positive predictive values were 100% for all sample types and both organisms, except male CT FCU (99.7% specificity (95% confidence interval (CI) 98.4–100.0; 356/357), 97.1% positive predictive value (95% CI 84.7–99.9; 33/34)). For CT, sensitivity was ≥94.3% for FCU and SCVS. CT sensitivity for female FCU was higher (100%; 95% CI, 88.1–100; 29/29) than for SCVS (96.4%; 95% CI, 81.7–99.9; 27/28). NG sensitivity and negative predictive values were 100% in FCU (male and female).

Conclusions

This prototype test has excellent performance characteristics, comparable to currently used NAATs, and fulfils several World Health Organization ASSURED criteria. Its rapidity without loss of performance suggests that once further developed and commercialized, this test could positively affect clinical practice and public health.

Prostate cancer in BRCA2 germline mutation carriers is associated with poorer prognosis

Background:

The germline BRCA2 mutation is associated with increased prostate cancer (PrCa) risk. We have assessed survival in young PrCa cases with a germline mutation in BRCA2 and investigated loss of heterozygosity at BRCA2 in their tumours.

Methods:

Two cohorts were compared: one was a group with young-onset PrCa, tested for germline BRCA2 mutations (6 of 263 cases had a germline BRAC2 mutation), and the second was a validation set consisting of a clinical set from Manchester of known BRCA2 mutuation carriers (15 cases) with PrCa. Survival data were compared with a control series of patients in a single clinic as determined by Kaplan–Meier estimates. Loss of heterozygosity was tested for in the DNA of tumour tissue of the young-onset group by typing four microsatellite markers that flanked the BRCA2 gene, followed by sequencing.

Results:

Median survival of all PrCa cases with a germline BRCA2 mutation was shorter at 4.8 years than was survival in controls at 8.5 years (P=0.002). Loss of heterozygosity was found in the majority of tumours of BRCA2 mutation carriers. Multivariate analysis confirmed that the poorer survival of PrCa in BRCA2 mutation carriers is associated with the germline BRCA2 mutation per se.

Conclusion:

BRCA2 germline mutation is an independent prognostic factor for survival in PrCa. Such patients should not be managed with active surveillance as they have more aggressive disease.

Association between hormonal genetic polymorphisms and early-onset prostate cancer

We investigated the association between seven polymorphisms in four candidate genes involved in vitamin D and androgen metabolism with early-onset prostate cancer (CaP) risk. The polymorphisms were genotyped in 288 UK males who were diagnosed with CaP at the age of 55 y or younger and up to 700 population-based controls. An additional 50 cases (not selected for age) and 76 controls were also genotyped. Short (< or =22 repeats) AR (CAG)(n) repeats were associated with a significantly reduced risk of early onset CaP (OR 0.68, 95% CI 0.50-0.91) compared with men with long (> 22) repeats. Men homozygous for the leucine variant of SRD5A2 p.89V > L were also found to be at a significantly increased risk of CaP compared with men who were homozygous for the valine allele (OR 1.84, 95% CI 1.15-2.98). No associations were found with the AR (GGC)(n), CYP17 Msp A1 I, VDR Taq I, SRD5A2 (TA)(n) and p.49A >T polymorphisms and CaP risk. These findings suggest that common polymorphisms in the AR and SRD5A2 genes may be associated with early-onset CaP in British men.

The association between polymorphisms in the CYP17 and 5alpha-reductase (SRD5A2) genes and serum androgen concentrations in men

Prospective studies suggest that prostate cancer risk may be increased in association with high serum concentrations of free testosterone and androstanediol glucuronide (A-diol-g). Polymorphisms have been identified in the 17-hydroxylase cytochrome P450 gene (CYP17) and the steroid 5alpha-reductase type II gene (SRD5A2), two genes that are involved in the biosynthesis and metabolism of androgens in men. The CYP17 MspA1 I polymorphism has been associated with increased prostate cancer risk, and the SRD5A2 V89L polymorphism has been associated with low A-diol-g in Asian men, a serum marker of 5alpha-reductase activity. The purpose of this study was to investigate the association between these two polymorphisms and serum sex hormone concentrations in 621 British men. In particular, we wanted to test the hypotheses that the A2 allele in the CYP17 gene is associated with increased serum testosterone concentrations, and the L allele in the SRD5A2 gene is associated with reduced A-diol-g concentrations. Mean hormone concentrations were evaluated in each genotype and adjusted for age and other relevant factors. We found no evidence that the CYP17 MspA1 I polymorphism was associated with higher testosterone levels. The L/L genotype of the SRD5A2 V89L polymorphism was associated with a 10% lower A-diol-g concentration, but this was not significant at the 5% level. However, the L/L genotype of the V89L polymorphism was associated with significantly lower concentrations of testosterone and free testosterone (by 12% and 16%, respectively) and an 8% higher sex hormone-binding globulin concentration. These results suggest that the CYP17 MspA1 I polymorphism is not associated with testosterone concentrations and that the SRD5A2 V89L polymorphism is not a strong determinant of A-diol-g concentration in Caucasian men.

Induction of ovulation with subcutaneous pulsatile gonadotropin-releasing hormone: correlation with body weight and other parameters

We treated 21 anovulatory infertile patients with subcutaneous pulsatile gonadotropin-releasing hormone (GnRH) administered via a syringe pump. Response to treatment was assessed by urinary estrogen excretion and ultrasound measurement of follicular growth. Ten patients ovulated and 8 subsequently conceived, for a total of 10 pregnancies. Human chorionic gonadotropin (hCG) was not administered routinely, but two patients required hCG to induce follicular rupture. The majority of the patients who conceived had a body mass index (BMI) of less than 21 and a luteinizing hormone (LH)/follicle-stimulating hormone ratio of less than 1. Conversely, those patients with either elevated BMI or LH or both generally failed to respond satisfactorily to this treatment. It is suggested that pulsatile GnRH is most likely to succeed in inducing ovulation if the BMI is less than 21 and the LH is normal, but is unlikely to be successful if there is both an elevated LH and a BMI of greater than 25. Between these two extremes, the response is variable and a therapeutic trial may be appropriate.

Menstrual pattern and fertility after treatment for anovulatory infertility

Sixty-four patients who had been treated for anovulatory infertility and subsequently conceived were reviewed. Information was obtained on subsequent menstrual pattern, contraception used, treatment required to achieve a further pregnancy and the interval to any such pregnancy. Almost half the group had regular cycles following delivery but 2 patients had a recurrence of post oral contraceptive amenorrhoea. Most patients conceived without treatment within 2 years of the initial pregnancy but 10 again required ovulation induction. It is concluded that there is no long-term irreversible suppression of hypothalamic function in this group of patients and, once a pregnancy has been achieved, the prognosis for future fertility without therapy is good.

Infertility: a review of 291 infertile couples over eight years

Two hundred and ninety-one infertile couples were studied over an 8-year period. Anovulation was the most common cause of infertility, being the causative factor in half of the patients. Ovulation induction with clomiphene or cyclic hormone therapy readily achieved pregnancy in the majority of these patients. The distribution of other etiologic factors was fairly uniform, but treatment was much less successful. Thorough evaluation of both partners is advised both for treatment purposes and as a more accurate guide to the prognosis for conception. Furthermore, even in the presence of oligospermia, ovulation induction may be successful in achieving a pregnancy.

Effects of posture and anxiety level on effectiveness of free association

Clinical observations have characterized low anxious (LA) Ss as possessing a repressive-denial defense pattern. The psychoanalytic notion that repression diminishes with relaxation and reduced motility on the couch was examined in the predictions that supine LA Ss would free-associate more effectively than supine HA Ss, but that the reverse would hold true in the sitting position. The 10 highest and lowest trait-anxiety rankings in each of the postural conditions were given Bordin's free-association procedure Results indicated a significant effect for posture and an interaction with anxiety level in the predicted direction. The differential effect of motility on repression in LA Ss vis-a-vis other defense styles in HA Ss was discussed.