Enhanced secrecy in optical communication using speckle from multiple scattering layers.

We study the secrecy of an optical communication system with two scattering layers, to hide both the sender and receiver, by measuring the correlation of the intermediate speckle generated between the two layers. The binary message is modulated as spatially shaped wavefronts, and the high number of transmission modes of the scattering layers allows for many uncorrelated incident wavefronts to send the same message, making it difficult for an attacker to intercept or decode the message and thus increasing secrecy. We collect 50,000 intermediate speckle patterns and analyze their correlation distribution using the Kolmogorov-Smirnov (K-S) test. We search for further correlations using the K-Means and Hierarchical unsupervised classification algorithms. We find no correlation between the intermediate speckle and the message, suggesting a person-in-the-middle attack is not possible. This method is compatible with any digital encryption method and is applicable for codifications in optical wireless communication (OWC).

Ultrafast RNA extraction-free SARS-CoV-2 detection by direct RT-PCR using a rapid thermal cycling approach.

The COVID19 pandemic has underlined the need for quick and high-throughput SARS-CoV-2 detection assays. Here we report the development of a direct RT-PCR detection method that can reliably detect SARS-CoV-2 gRNA in nasopharyngeal swab samples in under 27 minutes without needing nucleic acid extraction. Fluorescence readouts were highly linear, robust, and sensitive with a LoD95% of determined at 1.46 copies/µL as determined by RT-PCR on a surrogate sample panel containing clinical samples with varying SARS-CoV-2 viral load. We benchmarked our direct RT-PCR method against a reference qPCR method in 368 nasopharyngeal swab samples, confirming a sensitivity score of 99.4% and a specificity score of 98.5% as compared to the reference method. In summary, we here describe a novel rapid direct RT-PCR method to detect SARS-CoV-2 gRNA in clinical specimens, which can be completed in significantly less time compared to conventional PCR methods making it ideal for large-scale screening applications.

Treatment and Outcome of Culture-Confirmed Mycobacterium marinum Disease.

Background: Mycobacterium marinum is a nontuberculous mycobacterium that causes skin and soft tissue infections. Treatment consists of multiple antibiotics, sometimes combined with surgical debridement. There is little evidence for the choice of antibiotics, the duration of treatment, and the role of susceptibility testing. Methods: We performed a retrospective cohort study of culture-confirmed M. marinum infections in the Netherlands in the 2011-2018 period. Clinical characteristics, in vitro susceptibility, extent of disease, treatment regimens, and outcomes were analyzed. Incidence was assessed from laboratory databases. Results: Forty cases of M. marinum infection could be studied. Antibiotic treatment cured 36/40 patients (90%) after a mean treatment duration of 25 weeks. Failure/relapse occurred in 3 patients, and 1 patient was lost to follow-up. Antibiotic treatment consisted of monotherapy in 35% and 2-drug therapy in 63%. Final treatment contained mostly ethambutol-macrolide combinations (35%). Eleven patients (28%) received additional surgery. We recorded high rates of in vitro resistance to tetracyclines (36% of isolates). Tetracycline resistance seemed correlated with poor response to tetracycline monotherapy. The annual incidence rate was 0.15/100 000/year during the study period. Conclusions: Prolonged and susceptibility-guided treatment results in a 90% cure rate in M. marinum disease. Two-drug regimens of ethambutol and a macrolide are effective for moderately severe infections. Tetracycline monotherapy in limited disease should be used vigilantly, preferably with proven in vitro susceptibility.

[We still have to continue to test, test, test]. / We moeten nu nog blijven testen, testen, testen.

Testing for COVID-19 is performed curatively for disease detection and as screening tool to prevent spread for public health and infection prevention. Testing for access is an important additional measure to provide information about asymptomatic or pre-symptomatic infection. In a recent meta-analysis 42.8% showed no symptoms with an estimated percentage of asymptomatic infections of 35.1%. False positive testing is not completely preventable but allows events such as the Eurovision Song Contest, professional football, the Olympic Games or Formula 1. Their trade-off is not purely medical but also political-economical. The choice to carry out many Dutch tests in foreign laboratories is inefficient, while at the same time the opportunity to strengthen regional innovation, training and infrastructure is missed. Cooperation between municipal health departments and regional laboratories and extra service from regional laboratories (such as fast variant PCR) are frustrated this way. We hope this situation will improve rapidly.

Malaria diagnosis in a malaria non-endemic high-resource country: high variation of diagnostic strategy in clinical laboratories in the Netherlands.

BACKGROUND: Microscopic examination of thick and thin blood films is the gold standard in current guidelines for the diagnosis of malaria, but guidelines do not uniformly agree on which combination of other methods should be used and when. METHODS: Three questionnaires were sent between March 2018 and September 2019 to laboratories subscribing to the external quality assessment scheme for the diagnosis of blood and intestinal parasites of the Dutch Foundation for Quality Assessment in Medical Laboratories in order to investigate how much variation in the laboratory diagnosis of malaria between different clinical laboratories is present in the Netherlands. RESULTS: The questionnaires were partially or fully completed by 67 of 77 (87%) laboratories. Only 9 laboratories reported 10 or more malaria positive patients per year. Most laboratories use a different diagnostic strategy, within office versus outside office hours depending on the screening assay result. Within office hours, 62.5% (35/56) of the responding laboratories perform an immunochromatographic test (ICT) in combination with microscopic examination of thick and thin blood films without additional examinations, such as Quantitative Buffy Coat and/or rtPCR analysis. Outside office hours 85.7% (48/56) of laboratories use an ICT as single screening assay and positive results are immediately confirmed by thick and thin blood films without additional examinations (89.6%, 43/48). In case of a negative ICT result outside office hours, 70.8% (34/48) of the laboratories perform microscopic examination of the thick film the next morning and 22.9% (11/48) confirm the negative ICT result immediately. Furthermore, substantial differences were found in the microscopic examinations of thick and thin blood films; the staining, theoretical sensitivity of the thick film and determination of parasitaemia. CONCLUSIONS: This study demonstrated a remarkably high variation between laboratories in both their diagnostic strategy as well as their methods for microscopic examination for the diagnosis of malaria in a clinical setting, despite existing national and international guidelines. While the impact of these variations on the accuracy of the diagnosis of malaria is yet unknown, these findings should stimulate clinical laboratories to critically review their own diagnostic strategy.

Supplementing SARS-CoV-2 genomic surveillance with PCR-based variant detection for real-time actionable information, the Netherlands, June to July 2021.

We evaluated routine testing with SARS-CoV-2 Delta variant-specific RT-PCR in regional hospital laboratories in addition to centralised national genomic surveillance in the Netherlands during June and July 2021. The increase of the Delta variant detected by RT-PCR correlated well with data from genomic surveillance and was available ca 2 weeks earlier. This rapid identification of the relative abundance and increase of SARS-CoV-2 variants of concern may have important benefits for implementation of local public health measures.

C-reactive protein to rule out complicated pneumococcal disease manifestations: a retrospective cohort study in adults with pneumococcal bacteraemia.

OBJECTIVES: To explore the negative predictive value (NPV) of C-reactive protein (CRP) at admission to exclude complicated disease manifestations of pneumococcal disease. METHODS: A Dutch multicentre retrospective cohort study was conducted between 01-01-2012 and 30-06-2020. Adults with positive blood cultures for Streptococcus pneumoniae, whose CRP was measured at admission and whose infection focus was known, were included. Electronic medical and microbiological records were reviewed. RESULTS: Of the 832 bacteraemic patients enrolled, 30% had complicated manifestations of pneumococcal disease; most frequent were pleural effusion (8.9%), pleural empyema (5.4%) and meningitis (7.5%). Compared to solitary pneumonia, patients with pleural effusion and empyema presented with higher CRP levels. Although low CRP levels did not exclude complicated disease in general, a CRP level < 114 mg/L at admission could reliably exclude empyema among adult pneumonia patients with an NPV of 93% and a specificity of 26%. However, in cases where pleural fluid was present, CRP levels were mostly > 114 mg/L, such that suspicion of empyema could only be ruled out in a minority of cases (10%). CONCLUSIONS: Complicated manifestations are prevalent in adult pneumococcal bacteraemia. Low blood CRP levels can reliably exclude the development of pulmonary empyema. Practical value may be largest in settings without thoracic imaging at hand.

The drop in reported invasive pneumococcal disease among adults during the first COVID-19 wave in the Netherlands explained.

OBJECTIVES: Streptococcus pneumoniae is the leading bacterial pathogen causing respiratory infections. Since the COVID-19 pandemic emerged, less invasive pneumococcal disease (IPD) was identified by surveillance systems worldwide. Measures to prevent transmission of SARS-CoV-2 also reduce transmission of pneumococci, but this would gradually lead to lower disease rates. DESIGN: Here, we explore additional factors contributing to the instant drop in pneumococcal disease cases captured in surveillance. RESULTS: Our observations on referral practices and other impediments to diagnostic testing indicate that residual IPD has likely occurred but remained undetected by conventional hospital-based surveillance. CONCLUSIONS: Depending on the setting, we discuss alternative monitoring strategies that could improve understanding of pneumococcal disease dynamics.

The presence of Cutibacterium acnes on the skin of the shoulder after the use of benzoyl peroxide: a placebo-controlled, double-blinded, randomized trial.

HYPOTHESIS AND BACKGROUND: We hypothesized that benzoyl peroxide (BPO) would reduce the presence of Cutibacterium acnes on the skin of the shoulder by 50% compared with placebo. Infections after shoulder surgery are most commonly caused by C acnes. Current prophylactic methods do not effectively reduce the bacterial load of this bacterium. However, it seems that BPO may reduce C acnes on the skin of the shoulder. Therefore, this study aimed to investigate the effect of BPO on the presence of C acnes on the shoulder skin. METHODS: A double-blinded, randomized, placebo-controlled trial was performed including healthy participants aged between 40 and 80 years. Thirty participants with C acnes on the shoulder skin according to baseline skin swabs were randomized into the BPO or placebo group. After gel application 5 times, skin swabs were taken to determine the presence of C acnes. RESULTS: Forty-two participants were screened for the presence of C acnes to include 30 participants with the bacterium. Participants with C acnes at baseline were 7.4 years younger than participants without C acnes (P = .015). One participant in the placebo group dropped out before application because of fear of adverse events. After application, C acnes remained present in 3 of 15 participants (20.0%) in the BPO group and in 10 of 14 participants (71.4%) in the placebo group, resulting in a 51.4% reduction in the presence of C acnes. CONCLUSION: Applying BPO 5 times on the shoulder skin effectively reduces C acnes. Consequently, BPO may reduce the risk of postoperative infections.

[Complications after intravesical BCG instillation]. / Complicaties na intravesicale spoeling met Mycobacterium bovis BCG.

Complications after intravesicalMycobacterium bovisBCG instillation Intravesical instillation of Mycobacterium bovis BCG is frequently used for non-muscle invasive high-grade urothelial cell carcinoma of the bladder. M. bovisBCG is a mycobacterium and was one of the first cancer immunotherapies. It activates the immune system and so reduces disease recurrence. Although rare, this treatment can lead to mycobacterial infections or systemic immune reactions. Diagnosing these complications is often challenging because the symptoms are non-specific. In addition, M. bovisBCG infections are hard to detect with current diagnostics, i.e. bacterial cultures, PCR and radiological imaging. Thus, proper treatment is often delayed as M. bovis does not respond to conventional broad-spectrum antibiotics. In this article we present three patients with BCG pneumonia, BCG arthritis and BCG cystitis, respectively. Subsequently, we describe the history of M. bovis BCG, its pathophysiology, the clinical presentation of its complications and diagnostics and treatment.

Coma caused by Shigella toxin-producing Escherichia coli in the absence of haemorrhagic uraemic syndrome (HUS).

Shigella toxin-producing Escherichia coli (STEC) is well known for its complications such as haemolytic uraemic syndrome (HUS), but neurological symptoms have also been reported. While most cases of infection with STEC occur with concurrent HUS, we describe a patient with severe neurological symptoms in the absence of HUS. LEARNING POINTS: Shigella toxin producing Escherichia coli (STEC) are bacteria that cause haemorrhagic colitis.Generally, infections with STEC occur with a concurrent haemolytic uraemic syndrome (HUS).However, infections with STEC can occur with neurological symptoms without HUS.

Mosquito feeding assays to determine the infectiousness of naturally infected Plasmodium falciparum gametocyte carriers.

INTRODUCTION: In the era of malaria elimination and eradication, drug-based and vaccine-based approaches to reduce malaria transmission are receiving greater attention. Such interventions require assays that reliably measure the transmission of Plasmodium from humans to Anopheles mosquitoes. METHODS: WE COMPARED TWO COMMONLY USED MOSQUITO FEEDING ASSAY PROCEDURES: direct skin feeding assays and membrane feeding assays. Three conditions under which membrane feeding assays are performed were examined: assays with i) whole blood, ii) blood pellets resuspended with autologous plasma of the gametocyte carrier, and iii) blood pellets resuspended with heterologous control serum. RESULTS: 930 transmission experiments from Cameroon, The Gambia, Mali and Senegal were included in the analyses. Direct skin feeding assays resulted in higher mosquito infection rates compared to membrane feeding assays (odds ratio 2.39, 95% confidence interval 1.94-2.95) with evident heterogeneity between studies. Mosquito infection rates in membrane feeding assays and direct skin feeding assays were strongly correlated (p<0.0001). Replacing the plasma of the gametocyte donor with malaria naïve control serum resulted in higher mosquito infection rates compared to own plasma (OR 1.92, 95% CI 1.68-2.19) while the infectiousness of gametocytes may be reduced during the replacement procedure (OR 0.60, 95% CI 0.52-0.70). CONCLUSIONS: Despite a higher efficiency of direct skin feeding assays, membrane feeding assays appear suitable tools to compare the infectiousness between individuals and to evaluate transmission-reducing interventions. Several aspects of membrane feeding procedures currently lack standardization; this variability makes comparisons between laboratories challenging and should be addressed to facilitate future testing of transmission-reducing interventions.

Mycobacterium bovis infection in a young Dutch adult: transmission from an elderly human source?

A young female health professional was diagnosed with pulmonary tuberculosis caused by Mycobacterium bovis. Source finding and contact tracing was initiated by the regional municipal health service using both tuberculin skin test and QuantiFERON(®)-TB Gold (QFT-GIT (IGRA). The strain appeared near-identical to that of an elderly Dutch patient.

Human immune responses that reduce the transmission of Plasmodium falciparum in African populations.

Malaria-infected individuals can develop antibodies which reduce the infectiousness of Plasmodium gametocytes to biting Anopheles mosquitoes. When ingested in a bloodmeal together with gametocytes, these antibodies reduce or prevent subsequent parasite maturation in the insect host. This transmission-blocking immunity is usually measured in human sera by testing its effect on the infectivity of gametocytes grown in vitro. Here we evaluate evidence of transmission-blocking immunity in eight studies conducted in three African countries. Plasmodium falciparum gametocytes isolated from each individual were fed to mosquitoes in both autologous plasma collected with the parasites, and permissive serum from non-exposed donors. Evidence of transmission reducing effects of autologous plasma was found in all countries. Experiments involving 116 Gambian children (aged 0.5-15 years) were combined to determine which factors were associated with transmission reducing immune responses. The chances of infecting at least one mosquito and the average proportion of infected mosquitoes were negatively associated with recent exposure to gametocytes and sampling late in the season. These results suggest that effective malaria transmission-reducing antibodies do not commonly circulate in African children, and that recent gametocyte carriage is required to initiate and/or boost such responses.

Laboratory diagnosis of pulmonary tuberculosis in TB and HIV endemic settings and the contribution of real time PCR for M. tuberculosis in bronchoalveolar lavage fluid.

BACKGROUND: Tuberculosis (TB) in Africa is increasing because of the human immunodeficiency virus (HIV) epidemic, and in HIV/AIDS patients it presents atypically. Pulmonary tuberculosis (PTB) in Africa is mainly diagnosed clinically, by chest radiograph or by sputum smear for acid fast bacilli (AFB). METHODS: We evaluated in 120 HIV-infected patients with chest infection the diagnostic accuracy of AFB smear of sputum and bronchoalveolar lavage (BAL) fluid, sputum Mycobacterium tuberculosis (MTB) culture, real-time PCR and MycoDot serological test, using MTB culture of BAL fluid as gold standard. We correlated PCR cycle threshold values (C(T)) to the culture results. Retrospectively, we evaluated the development of active TB in patients with positive PCR but negative culture. RESULTS: Culture of BAL fluid identified 28 patients with PTB. Fifty-six patients could not produce adequate sputum. Sputum AFB smear and the serological test had sensitivities of 66.7% and 0%, respectively. PCR with C(T) 40 was positive in 73 patients, 27 of whom were also TB culture positive (96.4% sensitivity and 52.3% specificity of PCR). PCR with C(T) 32 had sensitivity of 85.7% and specificity of 90.9% to diagnose PTB in BAL. No patients with positive PCR but negative culture developed active TB during 18 months follow-up. CONCLUSION: In these HIV-infected patients, AFB smear and serology had very low sensitivities. PCR of BAL with C(T) value 32 had improved specificity to diagnose active PTB. A prospective follow-up study is warranted in TB/HIV endemic settings, applying real time PCR to both sputum and BAL.

M. tuberculosis genotypic diversity and drug susceptibility pattern in HIV-infected and non-HIV-infected patients in northern Tanzania.

BACKGROUND: Tuberculosis (TB) is a major health problem and HIV is the major cause of the increase in TB. Sub-Saharan Africa is endemic for both TB and HIV infection. Determination of the prevalence of M. tuberculosis strains and their drug susceptibility is important for TB control.TB positive culture, BAL fluid or sputum samples from 130 patients were collected and genotyped. The spoligotypes were correlated with anti-tuberculous drug susceptibility in HIV-infected and non-HIV patients from Tanzania. RESULTS: One-third of patients were TB/HIV co-infected. Forty-seven spoligotypes were identified. Fourteen isolates (10.8%) had new and unique spoligotypes while 116 isolates (89.2%) belonged to 33 known spoligotypes. The major spoligotypes contained nine clusters: CAS1-Kili 30.0%, LAM11- ZWE 14.6%, ND 9.2%, EAI 6.2%, Beijing 5.4%, T-undefined 4.6%, CAS1-Delhi 3.8%, T1 3.8% and LAM9 3.8%. Twelve (10.8%) of the 111 phenotypically tested strains were resistant to anti-TB drugs. Eight (7.2%) were monoresistant strains: 7 to isoniazid (INH) and one to streptomycin. Four strains (3.5%) were resistant to multiple drugs: one (0.9%) was resistant to INH and streptomycin and the other three (2.7%) were MDR strains: one was resistant to INH, rifampicin and ethambutol and two were resistant to all four anti-TB drugs. Mutation in the katG gene codon 315 and the rpoB hotspot region showed a low and high sensitivity, respectively, as predictor of phenotypic drug resistance. CONCLUSION: CAS1-Kili and LAM11-ZWE were the most common families. Strains of the Beijing family and CAS1-Kili were not or least often associated with resistance, respectively. HIV status was not associated with spoligotypes, resistance or previous TB treatment.

Real-time PCR for the detection of Dientamoeba fragilis in fecal samples.

A real-time polymerase chain reaction (PCR) method targeting the 5.8S ribosomal RNA gene was developed for the detection of Dientamoeba fragilis in stool samples. The PCR also included an internal control to detect inhibition of the amplification by fecal constituents in the sample. The assay was performed on species-specific DNA controls (n=29) and a range of stool samples (n=85), and achieved high specificity and sensitivity. D. fragilis DNA could be detected in unpreserved fecal samples up to 8 weeks after storage at 4 degrees C. The use of this assay in a diagnostic laboratory offers the possibility of introducing DNA detection as a feasible technique for the routine diagnosis of intestinal D. fragilis infections.