Ready for new waves: optimizing SARS-CoV-2 variants monitoring in pooled samples with droplet digital PCR

Introduction

The declaration of the end of the Public Health Emergency for COVID-19 on May 11th, 2023, has shifted the global focus led by WHO and CDC towards monitoring the evolution of SARS-CoV-2. Augmenting these international endeavors with local initiatives becomes crucial to not only track the emergence of new variants but also to understand their spread. We present a cost-effective digital PCR-based pooled sample testing methodology tailored for early variant surveillance.

Methods

Using 1200 retrospective SARS-CoV-2 positive samples, either negative or positive for Delta or Omicron, we assessed the sensitivity and specificity of our detection strategy employing commercial TaqMan variant probes in a 1:9 ratio of variant-positive to variant-negative samples.

Results

The study achieved 100% sensitivity and 99% specificity in 10-sample pools, with an Area Under the Curve (AUC) exceeding 0.998 in ROC curves, using distinct commercial TaqMan variant probes.

Discussion

The employment of two separate TaqMan probes for both Delta and Omicron establishes dual validation routes, emphasizing the method's robustness. Although we used known samples to model realistic emergence scenarios of the Delta and Omicron variants, our main objective is to demonstrate the versatility of this strategy to identify future variant appearances. The utilization of two divergent variants and distinct probes for each confirms the method's independence from specific variants and probes. This flexibility ensures it can be tailored to recognize any subsequent variant emergence, given the availability of its sequence and a specific probe. Consequently, our approach stands as a robust tool for tracking and managing any new variant outbreak, reinforcing our global readiness against possible future SARS-CoV-2 waves.

[What influences reconvalescence after lung resection?]

INTRODUCTION

Reconvalescence after lung resections underlies several influences. The aim of this study was to outline the effect of patient and operative factors.

METHODS

Between 1/97 and 6/98 a cross sectional prospective study was undertaken at the University of Ulm. 125 patients with lung resections for various reasons via anterolateral thoracotomy were included. Variants thought to affect postoperative recovery were statistically analysed using uni- and multivariate analysis. A "good postoperative recovery" (GPR) was seen as at least two of the following criteria were fulfilled on the second postoperative day: Spitzer Index >/=6, FEV1 >40% of preoperative measurement, pain on LASA scale </=3.

RESULTS

Chi-Square testing revealed a more frequent GPR for patients with benign diseases (61 vs 40%, p=0,0436), an atypical compared to anatomical resection (63 vs 40%, p=0,0157) and an opening of the retractor of not more than 13 cm (61 vs 34%, p=0,0033). Multivariate analysis demonstrated only the opening of the retractor as being of independent influence (p=0,0148). Age, sex, BMI, incision length, transsection of M. latissimus dorsi, number of accidental rib fractures, time of operation and routine of the surgeon were of no statistical relevance to GPR.

DISCUSSION

Malignant disease requiring anatomical lung resection is accompanied by delayed postoperative recovery when compared to lung resections for other reason. In contrast the width of opening of the retractor is of independent negative influence for reconvalescence. Once more the significance of a non-aggressive access procedure for lung resections is underlined.

In utero fetal muscle biopsy: a precious aid for the prenatal diagnosis of Duchenne muscular dystrophy

Prenatal diagnosis for Duchenne muscular dystrophy can usually be performed using DNA analysis. This approach would be impossible when there is only one prior affected male and no identifiable gene deletion. Therefore, in utero fetal thigh muscle biopsy with direct examination of muscle by dystrophin analysis may provide the only means of prenatal diagnosis. We report such a case in which fetal muscle biopsy was able to exclude Duchenne muscular dystrophy. A detailed literature review of the topic is provided.

Diagnosis and successful in utero treatment of a fetal goitrous hyperthyroidism caused by maternal Graves' disease. A case report

A case of maternal treated Graves' disease associated with hyperthyroid fetal goiter is presented. Fetal goiter is diagnosed by ultrasound and hyperthyroidism is confirmed by fetal blood sampling. Fetal thyroid status is normalized by maternal carbamizole treatment whereas the mother is euthyroid with replacement therapy after subtotal thyroidectomy. Repeated funipuncture allows us to adjust the fetal treatment. The infant is euthyroid at birth. Pathogenesis, diagnosis and treatment of fetal thyrotoxicosis complicated with maternal Graves' disease are discussed.

Prenatal diagnosis of a congenital astrocytoma: a case report and literature review

Congenital intracranial tumors are very rare. We report an endovaginal ultrasonographic diagnosis of an anaplastic astrocytoma at 31 weeks' gestation. Other means, such as antenatal magnetic resonance imaging and fetal blood sampling were not shown to have any diagnostic advantage. A detailed literature review of the topic is provided.

[The Infraguide system in laparoscopic surgery]

Infraguide is a system to transmit laser beams into the abdominal cavity through multiple reflexions in a hollow tube of ceramic mirror. The latter is protected by a metal tube of 3 mm outside diameter. After an experience of 45 cases, the authors analyse the advantages and the disadvantages of this system. The advantages are: the manageability, the small diameter, the excellent visibility of the pilot beam and the easy evacuation of the smoke. The disadvantage is minor: the focused spot cannot be smaller than 0.78 mm.

[Rupture of an unscarred uterus at full term after an intracervical application of dinoprostone (Prepidil) gel]

The authors report a case of uterine rupture following intra-cervical application of dinoprostone (two doses at an interval of 6 hours). No oxytocic had been administered and recording of the contractions had revealed no hyperkinesia or hypertonia one hour before rupture occurred.