Dry Swabs Research Articles

Pain Response to Open Label Placebo in Induced Acute Pain in Healthy Adult Males.

Open label placebos with patient education are effective in reducing chronic pain, and recent studies on their effect on pain have established interest in this field. Nevertheless, data on their effect on acute pain are scarce, and on hyperalgesia and allodynia, absent. This study assessed the effect of open label placebos on acute pain in healthy adult males and the influence of placebo education. Thirty-two healthy males were included in this prospective, randomized, assessor-blinded crossover, single-center study assessing pain intensities (via numeric rating scale), area of hyperalgesia (von Frey filament), and allodynia (dry cotton swab) in a pain model utilizing intracutaneous electrical stimulation. The authors compared the effect of intravenous open label placebo on pain compared to no treatment. The authors further examined the effect of placebo on hyperalgesia and allodynia, and the influence of education (short vs. detailed) before placebo application. Saliva cortisol concentrations were also measured. Pain ratings (median, first to third quartile) were 21% lower during placebo treatment compared to no treatment, 4.0 (3.2 to 4.9) versus 5.1 (4.7 to 5.4), respectively (P = 0.001). The areas of hyperalgesia and allodynia were lower during placebo treatment compared to no treatment (hyperalgesia, 30 cm [17 to 47] vs. 55 cm [42 to 68], P = 0.003; allodynia, 24 cm [11 to 39] vs. 45 cm [31 to 62], P = 0.007). This corresponds to reductions of 47%. The extent of placebo education had no effect on pain. Saliva cortisol decreased significantly over time and was under the limit of detectability in the majority of participants in postbaseline measurements in both treatment branches. Baseline cortisol was not associated with the placebo effect or strength applied of current to reach defined pain ratings. Open label placebos might play a role in multimodal analgesic concepts.

The double-swab technique versus single swabs for human DNA recovery from various surfaces

Most crime scene DNA evidence is retrieved using cotton swabs. Since the late 90’s, the double-swab technique has been favoured by many practitioners throughout the world. However, the superiority of double-swabbing over applying single wet swabs has not been broadly verified. Here we set out to evaluate the need for the second dry swab for various surfaces, aiming at mimicking the range of surfaces encountered at crime scenes: flat and ridged, absorbing and non-absorbing. For the tested non-absorbing surfaces, i.e., window glass, steel, brass, synthetic leather and ridged plastic, the first wet swabs gave at least 16 times higher DNA yields compared to the second dry swabs. In addition, second wet swabs gave more DNA than second dry ones, opposing the common notion that the purpose of the second swab is to absorb excess liquid. When ten experienced staff members sampled saliva stains on a window glass surface the variation between persons was considerable, with mean DNA yields for the first wet swabs ranging from 0.045 ± 0.022 to 0.13 ± 0.024 ng/μL. The first wet swabs gave 4–162 times more DNA than the second dry swabs, with higher DNA amounts on second swabs coinciding with lower amounts for first swabs. We show that for non-absorbing surfaces, the first wet swab takes up most of the cells in dried stains, making it less valuable to apply a second dry swab. The differences in DNA recovery between first and second swabs were notable also for absorbing surfaces. Double-swabbing may be preferable for some complex surfaces, but focusing on efficient sampling technique with single wet swabs is likely a better general approach.

An evaluation of antimicrobial potential of irreversible hydrocolloid impression material incorporated with chitosan.

Aim:To evaluate the antimicrobial potential of irreversible hydrocolloid impression material manipulated using chitosan impregnated solution at various time intervals.Setting and Design:Evaluative invivo study design.Materials and Methods:Maxillary impressions made for 20 dentulous volunteers using irreversible hydrocolloid impression material manipulated using distilled water as control and using 1% chitosan impregnated solution as test group using stock metal trays with one-week interval. Bacterial samples were collected using dry sterile cotton swab in the mid-palatal region at the time intervals of 0, 10, 20 minutes. Bacterial swabs were inoculated on nutrient agar media and incubated at 37° C for 24 hours. Bacterial colonies were counted with the aid of colony counter.Statistical Analysis Used:The resultant data was subjected to statistical analysis using repeated measures ANOVA and independent t test.Results:Adding water soluble chitosan to irreversible hydrocolloid impression material resulted in superior antimicrobial activity. With the passage of time there was a significant decrease in the microbial colony count upto 10min (p=0.016). However, the rate of decrease of microbial colony count was statistically insignificant between the samples collected at 10 and 20 min.Conclusion:Incorporation of water soluble chitosan to irreversible hydrocolloid impression material showed significant antimicrobial activity in 10 minutes.

Testing a possible new way to diagnose scabies

This study, from a group based in different centres in France, has investigated a new non‐invasive (doesn't harm the skin in any way) method of diagnosing scabies. Scabies is an infestation due to a mite, sometimes called the itch mite, which burrows into the human skin causing a highly itchy rash. It is seen in children and the elderly, but it can affect people of any age and can be spread from person to person. It is difficult to diagnose as the main methods are either to take scrapings from the skin surface, or to examine the skin closely using a dermatoscope (surface microscope); both techniques require skill and interpretation. The new test discussed in this study is based on the rapid diagnostic technique known as the polymerase chain reaction, or PCR, which is used to identify specific pieces of the genetic code or DNA of the infecting organism, in this case a parasite, in skin material. The technique is simple to apply and uses a moistened swab which is lightly brushed over the affected areas, and this is then subjected to the PCR assay. In the study, about 38% of those patients with scabies infection, which had been proven using dermoscopy, had positive responses (i.e. shown to have scabies) in the new test. None of those without scabies infections were positive on PCR testing. This is the first step in the development of a potentially useful diagnostic technique. While the accuracy needs to be improved, it may become a useful tool for starting an investigation of a potential outbreak of scabies and, in the future, in diagnosing individual patients, rapidly and accurately. This summary relates to the study: Scabies polymerase chain reaction with standardized dry swab sampling: an easy tool for cluster diagnosis of human scabies

Liquid and Dry Swabs for Culture- and PCR-Based Detection of Colonization with Methicillin-Resistant Staphylococcus aureus during Admission Screening.

Rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) colonization status facilitates isolation and decolonization and reduces MRSA infections. Liquid but not dry swabs allow fully automated detection methods. However, the accuracy of culture and polymerase chain reaction (PCR) using liquid and dry swabs has not been analyzed. We compared different swab collection systems for routine nasal–throat MRSA screening in patients admitted to a tertiary care trauma center in Germany. Over 3 consecutive months, dry swabs (month 1), ESwabs (month 2), or MSwabs (month 3) were processed using Cepheid GeneXpert, Roche cobas and BD-MAX™ MRSA tests compared to chromogenic culture. Among 1680 subjects, the MRSA detection rate using PCR methods did not differ significantly between dry swabs, ESwab, and MSwab (6.0%, 6.2%, and 5.3%, respectively). Detection rates using chromogenic culture were 2.9%, 3.9%, and 1.9%, using dry, ESwab, and MSwab, respectively. Using chromogenic culture as the “gold standard”, negative predictive values for the PCR tests ranged from 99.2–100%, and positive predictive values from 33.3–54.8%. Thus, efficient and accurate MRSA screening can be achieved using dry, as well as liquid E- or MSwab, collection systems. Specimen collection using ESwab or MSwab facilitates efficient processing for chromogenic culture in full laboratory automation while also allowing molecular testing in automated PCR systems.

Optimising the use of molecular tools for the diagnosis of yaws.

Yaws is a neglected tropical disease and results in lesions of skin, soft tissues and bones. PCR plays an important part in surveillance. Children suspected to have yaws were enrolled. From the largest lesion, paired swabs were collected, one in transport medium and one as a dry swab. In children with multiple lesions we collected additional swabs from up to four subsequent lesions. Swabs in transport medium were maintained in a cold chain while dry swabs were stored at ambient temperature. Swabs were tested by PCR for Treponema pallidum and Haemophilus ducreyi. Of 55 individuals, 10 (18%) had at least one positive PCR for T. pallidum and 12 (22%) had at least one positive result for H. ducreyi. Concordance was 100% between swabs in transport medium and dry swabs. One patient had PCR-confirmed yaws on the swab of a third lesion when both the first and second lesions were PCR-negative. Storing swabs in transport medium and transporting in a cold chain did not improve yield, however, detection of T. pallidum is increased by swabbing additional lesions. As the target for yaws is eradication, approaches to sample collection need revisiting to ensure cases are not missed.

Implementation of HPV-based Cervical Cancer Screening Combined with Self-sampling Using a Midwifery Network Across Rural Greece: The GRECOSELF Study

Self-sampling for human papillomavirus (HPV) testing is an alternative to physician sampling particularly for cervical cancer screening nonattenders. The GRECOSELF study is a nationwide observational cross-sectional study aiming to suggest a way to implement HPV-DNA testing in conjunction with self-sampling for cervical cancer screening in Greece, utilizing a midwifery network. Women residing in remote areas of Greece were approached by midwives, of a nationwide network, and were provided with a self-collection kit (dry swab) for cervicovaginal sampling and asked to answer a questionnaire about their cervical cancer screening history. Each sample was tested for high-risk (hr) HPV with the Cobas HPV test. HrHPV-Positive women were referred to undergo colposcopy and, if needed, treatment according to colposcopy/biopsy results. Between May 2016 and November 2018, 13,111 women were recruited. Of these, 12,787 women gave valid answers in the study questionnaire and had valid HPV-DNA results; hrHPV prevalence was 8.3%; high-grade cervical/vaginal disease or cancer prevalence was 0.6%. HrHPV positivity rate decreased with age from 20.7% for women aged 25-29 years to 5.1% for women aged 50-60 years. Positive predictive value for hrHPV testing and for HPV16/18 genotyping ranged from 5.0% to 11.6% and from 11.8% to 27.0%, respectively, in different age groups. Compliance to colposcopy referral rate ranged from 68.6% (for women 25-29) to 76.3% (for women 40-49). For women residing in remote areas of Greece, the detection of hrHPV DNA with the Cobas HPV test, on self-collected cervicovaginal samples using dry cotton swabs, which are provided by visiting midwives, is a promising method for cervical cancer secondary prevention.

The effect of climatic simulations on DNA persistence on glass, cotton and polyester

It is important to understand the variables impacting DNA persistence when considering the recovery, and evaluative interpretation, of DNA evidence from crime scenes. Whilst it is known that temperature, humidity and UV affect DNA persistence, little research has been conducted to explore these effects in a combined and controlled manner. This study includes two experiments in which a climate chamber was used to simulate climatic conditions over a repeating 24-h period. Aliquots of ∼50 ng DNA were added to each substrate and DNA recovered at 0, 1, 3 and 7 days after deposition. Samples were run in triplicate, extracted and quantified. The first experiment investigated the effect of typical Southern English winter and summer days on DNA persistence on glass and cotton, with DNA being recovered by wet and dry swabs from glass and mini-tapes from cotton. The second experiment investigated the effect of typical Northern Italian winter and summer days on DNA persistence on cotton and polyester, with DNA being recovered by wet and moist swabs from both fabrics. Quantities of DNA on all substrates significantly declined over 7 days under summer conditions (p < 0.05), and more DNA tended to persist on the fabric substrates in both studies under conditions of winter than summer. These results contribute to our understanding of DNA persistence under different climatic conditions and will help inform investigators’ DNA recovery strategies.

The effects of various household cleaning methods on DNA persistence on mugs and knives

With the prevalence of forensic science in popular media, offenders are becoming more forensically aware and can employ precautionary methods, such as cleaning used items or rubbing away fingermarks, to reduce their traces left at a crime scene. This study examined the effects of various cleaning methods on DNA persistence on commonly encountered casework exhibits, specifically knives and mugs. Aliquots of acellular DNA were added to the knife handles or mug rims, allowed to dry, and then the substrates were either sampled directly or were cleaned and then sampled. The plastic- and wood-handled knives were cleaned with a cloth in a sink of water, diluted dish washing liquid or diluted household bleach, whereas the ceramic, glass and steel mugs were cleaned with a dry or wet cloth, or by wiping with a cloth after applying a cleaning product (dish washing liquid or household bleach spray) directly into the mug and then rinsing it with water. DNA samples were collected with wet and dry swabs, in triplicate, and extracted and quantified. In both experiments, DNA was not detected on items after cleaning with dish washing liquid or household bleach, irrespective of the differences in amounts of DNA initially deposited, substrates, and cleaning methods. Even without a cleaning product, rubbing with a dry cloth decreased DNA recovery from the mugs, regardless of the mug substrate. These results contribute to our understanding of the impact of various cleaning methods on DNA recovery at the crime scene and will help inform DNA recovery strategies.

Risk Factors and Microbiological Control of Soils, Surfaces and Medical-technical Equipment at the Abomey-Calavi / So-Ava University Hospital Center, Benin

Aims: The aim of our work was, on the one hand, to evaluate the risk factors for infectious contamination in hospital environments and, on the other hand, to carry out a microbiological control of surfaces at the Abomey-Calavi / So-Ava hospital in Benin.&#x0D; Methodology: The risk factors were evaluated using structured interviews based on the questionnaire. Fifty-five health care workers were surveyed and the questionnaire focused on: i) knowledge of care-associated infections and risk factors, ii) services most affected by care-associated infections and iii) origin of care-associated infections. For the microbial quality control of medical surfaces and materials, samples were collected by the dry swab method and the microbial isolation was carried out on Chapman and EMB agar plates. The biochemical analyses were carried out for the confirmations.&#x0D; Results: Out of 55 respondents, the 93% think that bacterial germs are often involved in care-associated infections. In addition, 80% of respondents believe that the healthcare environment may be the source of care-associated infections. Regarding the microbiological quality of the surfaces, out of 96 samples collected, 77% were contaminated with Staphylococcus spp and 30% with Enterobacteria. Concerning units’ contamination, the highest prevalence was observed in paediatrics with 92% of samples contaminated with Staphylococcus spp followed by the operating theatre (87%).&#x0D; Conclusion: It is clear from our work that hygiene managers must carry out preventive and corrective actions for the respect of the principles of hygiene. It would also be important to conduct regular microbiological monitoring of surfaces to identify any contamination.

Scabies polymerase chain reaction with standardized dry swab sampling: an easy tool for cluster diagnosis of human scabies.

Expert visualization of Sarcoptes scabiei remains essential for diagnosing human scabies, but access to said experts can be difficult. Polymerase chain reaction (PCR) is a specific tool for the detection and confirmation of S. scabiei but has poor sensitivity. To evaluate PCR as a diagnostic method for scabies using nonexpert-dependent standardized sampling. The dry swab was systematically rubbed across the front of both wrists, the eight interdigital spaces and on any suspected scabies lesions in all patients referred for scabies. A new PCR-based diagnostic test was run on the samples. All patients underwent clinical and dermoscopic examination. Scabies diagnosis was confirmed when dermoscopic examination was positive or the patient had typical clinical signs of scabies. Of 183 suspected cases of scabies, 164 patients were sampled, 87 had confirmed scabies (dermoscopy positive n = 87, typical clinical signs n = 1) and 77 did not. Of the 87 patients with proved scabies, 33 patients had positive scabies PCR, resulting in a 37·9% [95% confidence interval (CI) 28·4-48·4%] sensitivity and a 61·7% (95% CI 52·4-72·7%) negative predictive value. None of the 77 patients ruled out for scabies had a positive PCR result. This method is nontraumatic, repeatable and non-expert-dependent. It shows sensitivity similar to previous studies involving expert skin scraping. However, this method facilitates the multiplication of sampling, which increased the sensitivity for cluster scabies diagnosis. This method may be suitable as a first-line diagnosis tool where a large cluster scabies outbreak is suspected. What's already known about this topic? Scabies diagnosis requires expertise. Scabies polymerase chain reaction (PCR) is specific but has poor sensitivity. Poor sensitivity is the consequence of the low efficiency of sampling methods. What does this study add? This PCR-based diagnostic method based on nontraumatic standardized skin sampling is not expert-dependent and is reproducible. This diagnostic method may be relevant as a non-expert sentinel diagnosis tool in large clusters where a scabies outbreak is suspected.

Touch DNA: impact of handling time on touch deposit and evaluation of different recovery techniques: An experimental study

“Touch DNA” is DNA obtained from biological material transferred from a donor to an object or a person during physical contact. This particular kind of evidence could play an essential role in forensic laboratory work and is considered an important tool for investigators. Even though the principal aspects of “Touch DNA” have been extensively studied, to date, there are few reports in the research field of DNA retrieval from garments that have been worn. This study aimed to investigate the “handling time”, analyzing particularly the minimum contact time required to deposit a sufficient amount of DNA on a garment to produce an interpretable profile of the “handler”. Moreover, three different sampling techniques were compared (“dry swab”, “cutting out”, and “adhesive tape”) with the aim of defining the technique that guarantees the best recovery of the three methods tested. Analyzing the data of this experimental model, a “handling time” of two seconds is enough to release sufficient DNA on to a garment to obtain a complete profile. Moreover, this study demonstrated that when targeting for foreign DNA, the sample area should be narrowed down as much as possible to the smallest area possible to maximize target DNA recovery.

Porcine reproductive and respiratory syndrome virus RNA detection in different matrices under typical storage conditions in the UK.

In the UK, approximately 40 per cent of the pig breeding herds are outdoors. To monitor their porcine reproductive and respiratory syndrome virus (PRRSV) status, blood is collected commonly from piglets around weaning. Sample collection in British outdoor pigs often occurs during the early morning hours when the piglets tend to accumulate inside sheltered areas. For practical reasons, dry cotton swabs are occasionally used for blood collection and stored at room temperature until arrival in the laboratory. Detection of PRRSV RNA is a function of viral concentration, sample type and storage condition. To evaluate a possible impact of the sampling protocol on PRRSV1 detection, experimentally spiked blood samples using three dilutions of a representative PRRSV1 strain were prepared. In addition, blood samples from pigs naturally infected with PRRSV were obtained from a PRRSV-positive British herd. Spiked blood and blood from infected pigs were used to obtain sera, dry or wet (immersed in saline) polyester or cotton swabs and FTA cards. The different samples were stored for 24 hours, 48 hours or 7 days at 4°C or 20°C and tested by a real-time reverse transcriptase PRRSV PCR assay. Under the study conditions, the best matrix was serum (96.7 per cent), followed by wet swabs (78 per cent), dry swabs (61.3 per cent) and FTA cards (51 per cent). Polyester swabs (76 per cent) showed a better performance than cotton swabs (63.3 per cent). The reduction in sensitivity obtained for swabs and FTA cards was particularly high at low viral concentrations. The results indicate that wet polyester swabs should be used whenever possible.

Assay Integrity of a PCR Influenza Point-of-Care Test Remains Following Artificial System Contamination.

Healthcare providers who have access to tests at the point of care (POC) are increasingly requesting the same performance from the POC test as they expect from the laboratory. With the introduction of the cobas® Liat instrument, highly sensitive molecular diagnostic testing can be performed closer to the patient in CLIA-waived, POC settings. As more sensitive tests become available, there is concern regarding contamination of instrumentation owing to improper handling, mistakes made when processing, or environmental contamination. Recent concerns were raised when a nurse performed environmental surveillance for flu A/B by inserting a dry swab into the cobas Liat instrument and then ran it as a sample on the instrument, generating a positive result. This finding stimulated questions about the possibility of system contamination contributing to false-positive results, ultimately leading to the possibility of providing incorrect treatment to patients. To assess the likelihood of system contamination contributing to the generation of false-positive results, in this study we contaminated a cobas Liat System with flu A/B-positive control material. The system contamination was then assessed by swabbing exposed surfaces. Following confirmed system contamination, negative control samples were processed to determine whether system contamination had an impact on the expected negative results. Instrument contamination was confirmed, and no detectable flu A/B signal was observed for any of the negative control tubes run immediately following confirmation of system contamination. Environmental contamination of the Liat instrument does not have an impact on the integrity of the result.

Diagnostic Value of Histological Analysis of Punch Biopsies in Suspected Cutaneous Buruli Ulcer: A Study on 32 Cases of Confirmed Buruli Ulcer in Cameroon

Background: Buruli ulcer (BU) is a cutaneous infectious disease caused by Mycobacterium ulcerans. In this prospective study, we aim to clarify the main histopathological features of cutaneous BU based on 4-mm skin punch biopsies and to evaluate the diagnostic value of this method. Methods: Between 2011 and 2013, a prospective study was conducted in Cameroon. Dry swabs from ulcerative lesions and fine-needle aspirates of nonulcerative lesions were examined for Ziehl-Neelsen (ZN) staining, followed by PCR targeting IS2404 and culture. Two 4-mm punch biopsies were performed in the center and in the periphery of each lesion. Results: The 364 patients included in the study had 422 lesions (381 were ulcerative and 357 lesions were biopsied). Among the 99 ulcerated lesions with a final diagnosis of BU, histological features for BU were fulfilled in 32 lesions. 32/32 showed subcutaneous necrosis with a neutrophilic inflammatory infiltrate. 26/32 presented alcohol-resistant bacilli confirmed by ZN stain on histology. Conclusion: Punch biopsies help in establishing the correct diagnosis of BU and also in the differential diagnosis of chronic ulcers. The main histological feature for BU is diffuse coagulative necrosis of subcutaneous tissue, with acid-fast bacilli detected by ZN stain.

Laboratory diagnosis of congenital CMV infection in newborns: Impact of pre-analytic factors

BackgroundTo identify infants with congenital cytomegalovirus (cCMV) saliva polymerase chain reaction (PCR) is an ideal screening method. However, there are only few data on the influence of pre-analytic factors on the analytical sensitivity of the CMV PCR. ObjectivesThis study aimed to evaluate the performance of different swabbing materials, transport time and initial virus concentration regarding to the efficacy of recovery of CMV-DNA. Study designTwo CMV suspensions containing a high or low concentration of the laboratory strain AD 169 were prepared as test samples. Sampling was simulated by immersion of different swabs in these CMV suspensions and storing the swabs dry or in specified transport media. Transport conditions were modeled by storing the samples for defined time periods prior to DNA extraction and quantitative PCR analyses. Parallel analyses in two different laboratories allowed determination of lab to lab consistency. ResultsThe duration of storage under the conditions analysed did not have a major effect on the recovery efficiency for the swabbing materials tested. With exception of flocked dry swabs, all tested swabbing materials demonstrated good recovery of CMV DNA. The flocked swab/eNAT system showed the best overall performance. ConclusionsAll tested swabbing materials (with exception of the flocked dry swabs) seem to be well suited for recovery of CMV DNA and appropriate for use for the diagnosis of cCMV infection in symptomatic cases and in general cCMV screening programs of newborns.

Comparison of collection methods for molecular detection of α-herpes viruses and Treponema pallidum, including evaluation of critical transportation conditions

The detection of herpes simplex viruses and Treponemal pallidum from genital lesions requires efficient sampling of genetic material for a reliable molecular diagnosis. From 460 patients attending the Public Health clinic, two swabs (dry cotton swabs and Eswabs) per patient were collected in alternating order from the same lesion. Additionally, three storage conditions of Eswabs up to 28 days were evaluated to assess the stability of DNA over time. Out of the 830 PCRs performed, 20 (2.4%) PCRs were discordant between the two swabs. No significant differences were observed between the two sample types. HSV1 and HSV2 could be reliably detected from Eswabs up to 28 days when kept at room temperature. A single swab from a genital lesion is sufficient for reliable diagnosis of α-herpes viruses and Treponemal pallidum, for which both a dry cotton swab or Eswab could be used.

Estimating Diphenylamine in Gunshot Residues from a New Tool for Identifying both Inorganic and Organic Residues in the Same Sample

A method involving the collection and determination of organic and inorganic gunshot residues on hands using on-line in-tube solid-phase microextraction (IT-SPME) coupled to miniaturized capillary liquid chromatography with diode array detection (CapLC-DAD) and scanning electron microscopy coupled to energy dispersion X-ray (SEM-EDX), respectively, for quantifying both residues was developed. The best extraction efficiency for diphenylamine (DPA) as the main target among organic residues was achieved by using a dry cotton swab followed by vortex-assisted extraction with water, which permits preservation of inorganic residues. Factors such as the nature and length of the IT-SPME extractive phase and volume of the sample processed were investigated and optimized to achieve high sensitivity: 90 cm of TRB-35 (35% diphenyl, 65% polydimethylsiloxane) capillary column and 1.8 mL of the processed sample were selected for the IT-SPME. Satisfactory limit of detection of the method for analysis of DPA deposited on shooters’ hands (0.3 ng) and precision (intra-day relative standard deviation, 9%) were obtained. The utility of the described approach was tested by analyzing several samples of shooters’ hands. Diphenylamine was found in 81% of the samples analyzed. Inorganic gunshot residues analyzed by SEM-EDX were also studied in cotton swab and lift tape kit samplers. Optical microscopy was used to see the inorganic gunshot residues in the cotton swab samplers. The lift tape kits provided lesser sensitivity for DPA than dry cotton swabs—around fourteen times. The possibility of environmental and occupational sources could be eliminated when DPA was found together with inorganic residues. Then, the presence of inorganic and organic residues in a given sample could be used as evidence in judicial proceedings in the forensic field.

Optimization of a Loop Mediated Isothermal Amplification (LAMP) Assay for In-Field Detection of Dichelobacter nodosus With aprV2 (VDN LAMP) in Victorian Sheep Flocks.

Dichelobacter nodosus is the primary etiological agent of footrot in sheep and has a variety of virulence factors. Of these, AprV2, an extracellular protease, has been shown to be capable of causing severe or “virulent” disease symptoms under the right conditions. Due to this, a loop-mediated isothermal amplification (LAMP) assay for the detection of aprV2-positive D. nodosus (VDN LAMP) was developed and evaluated for field use. A sample of 19 sheep flocks (309 sheep) in Victoria, Australia, were tested to determine the optimum conditions for in-field VDN LAMP assay use and sampling, for detecting aprV2-positive D. nodosus infected sheep. VDN LAMP performance was compared to a validated rtPCR that detects aprV2 and the benign strain counterpart, aprB2, using biologically duplicate samples to determine sensitivity and specificity. Flocks were sampled either in winter-spring (moist) or early summer (dry) conditions and had a range of clinical expressions of the disease ovine footrot. Variables considered for optimizing field performance were: sample collection method, sample preparation, clinical expression of disease, and nature of the feet when sampled (moist vs. dry, clean vs. soiled). The test was found to perform best when sheep were sampled with moist, clean feet, using a dry swab with the sample prepared in alkaline polyethylene glycol, pH 13.0, as the collection buffer. A sensitivity of 89% and specificity of 97% was seen when used in-field under these conditions, when compared to aprV2 detection by rtPCR, with “very good” agreement to rtPCR results. This study shows the VDN LAMP test is easy to use in-field to identify the presence of aprV2-positive D. nodosus in sheep flocks.

The colonization rate of needleless connector and the impact of disinfection for 15 s on colonization: A prospective pre- and post-intervention study.

The optimal scrubbing time for the disinfection of the surface of needleless connectors has not been determined. The evidence for successful needleless connector decontamination with 70% isopropyl alcohol ranges from 5 to 60 s. The aim of this prospective study was to identify colonization on the external surface of needleless connectors on central venous catheters and measure the efficiency of 15 s of scrubbing with 70% alcohol. A total of 31 patients were included. Samples were collected adhering to aseptic no-touch technique policies. Two samples were collected from the injectable surface of the needleless connector with sterile sodium chloride 0.9% moistened and a dry swab from the same site. Then the surface was scrubbed with alcohol 70% for 15 s for disinfection and second couples of samples for the cultures were taken after disinfection. A total of 420 swabs were obtained. The number of colonization (equal or higher than 15 CFU/plate) was present on 21 of the needleless connectors (20.0%). Coagulase-negative staphylococci was responsible for all the colonization. After disinfection for 15 s, no isolation exceeding 1 CFU/plate was present. Scrubbing for 15 s with 70% alcohol was found to be successful at elimination of colonization of the surface of needleless connector even in high microorganism counts.