Last data update: Apr 22, 2024. (Total: 46599 publications since 2009)
Records 1-27 (of 27 Records) |
Query Trace: Smith JP [original query] |
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Tuberculosis preventive treatment update - U.S. President's Emergency Plan for AIDS Relief, 36 Countries, 2016-2023
Ajiboye AS , O'Connor S , Smith JP , Ahmedov S , Coggin WL , Charles M , Ghosh S , Pierre P , Shah N , Teran RA , Moonan PK , Date A . MMWR Morb Mortal Wkly Rep 2024 73 (11) 233-238 Tuberculosis (TB) is the leading cause of death among persons with HIV. In 2022, an estimated 167,000 TB-related deaths occurred globally among persons with HIV. TB preventive treatment (TPT) helps prevent TB disease and is recommended for persons at high risk for developing TB, including those with HIV. TPT, when taken with antiretroviral treatment (ART), can reduce TB-attributable deaths among persons with HIV. In 2018, the U.S. President's Emergency Plan for AIDS Relief (PEPFAR) program committed to offer one course of TPT to all eligible clients receiving ART. This analysis describes trends in TPT initiation and completion among PEPFAR-supported programs in 36 countries in Africa, Central and South America, and Asia during fiscal years (FYs) 2017-2023. Overall, TPT initiation rates peaked in FY19, a possible sign of programmatic saturation. TPT initiation among clients who had been on ART <6 months reached 59%, and overall completion rates up to 87% were reported. Approximately 13 million persons with HIV have completed TPT since FY17, but widespread adoption of shorter regimens, patient-centered approaches, and electronic medical record systems might be needed to ensure full TPT coverage. Through PEPFAR's partnership with national HIV programs, TPT has become the standard of care for persons with HIV. |
Long-term follow-up of persons diagnosed with multidrug-resistant TB in Chennai, India, 2013-2020
Surie D , Sathyanarayanan MK , Lavanya J , Smith JP , Shanmugam SK , Tamilzhalagan S , Selvaraj A , Ramesh G , Tripathy S , Khaparde SD , Ho CS , Hall-Eidson PJ , Ranganathan UDK , Selvaraju S , Moonan PK . Int J Tuberc Lung Dis 2024 28 (1) 54-56 India has the largest number of multidrug-resistant TB | (MDR-TB) cases, defined as Mycobacterium tuberculosis | resistant to at least isoniazid (INH) and rifampicin (RIF).1 | However, less than half of all persons with MDR-TB in | India successfully complete treatment.1 Although initial | end-of-treatment outcomes offer a standardised time point | to assess the effect of treatment, these tend to | underestimate the overall burden of unfavourable longterm outcomes among persons treated for TB.2,3 The longterm outcomes of persons diagnosed with MDR-TB in | India, including the proportion with recurrent TB disease | or mortality, are unknown. This analysis was conducted | under programmatic conditions in a high-burden setting, | with no regular check-ups after treatment. The results can | be used to show the burden of recurrent illness and death | following treatment, and can be used as a benchmark to | measure improvement. |
Home-based testing and COVID-19 isolation recommendations, United States
Moonan PK , Smith JP , Borah BF , Vohra D , Matulewicz HH , DeLuca N , Caruso E , Loosier PS , Thorpe P , Taylor MM , Oeltmann JE . Emerg Infect Dis 2023 29 (9) 1921-1924 Using a nationally representative panel survey, we examined isolation behaviors among persons in the United States who had positive SARS-CoV-2 test results during January 2021-March 2022. Compared with persons who received provider-administered results, persons with home-based results had 29% (95% CI 5%-47%) lower odds of following isolation recommendations. |
Machine learning to predict bacteriologic confirmation of Mycobacterium tuberculosis in infants and very young children
Smith JP , Milligan K , McCarthy KD , McHembere W , Okeyo E , Musau SK , Okumu A , Song R , Click ES , Cain KP . PLOS Digit Health 2023 2 (5) e0000249 Diagnosis of tuberculosis (TB) among young children (<5 years) is challenging due to the paucibacillary nature of clinical disease and clinical similarities to other childhood diseases. We used machine learning to develop accurate prediction models of microbial confirmation with simply defined and easily obtainable clinical, demographic, and radiologic factors. We evaluated eleven supervised machine learning models (using stepwise regression, regularized regression, decision tree, and support vector machine approaches) to predict microbial confirmation in young children (<5 years) using samples from invasive (reference-standard) or noninvasive procedure. Models were trained and tested using data from a large prospective cohort of young children with symptoms suggestive of TB in Kenya. Model performance was evaluated using areas under the receiver operating curve (AUROC) and precision-recall curve (AUPRC), accuracy metrics. (i.e., sensitivity, specificity), F-beta scores, Cohen's Kappa, and Matthew's Correlation Coefficient. Among 262 included children, 29 (11%) were microbially confirmed using any sampling technique. Models were accurate at predicting microbial confirmation in samples obtained from invasive procedures (AUROC range: 0.84-0.90) and from noninvasive procedures (AUROC range: 0.83-0.89). History of household contact with a confirmed case of TB, immunological evidence of TB infection, and a chest x-ray consistent with TB disease were consistently influential across models. Our results suggest machine learning can accurately predict microbial confirmation of M. tuberculosis in young children using simply defined features and increase the bacteriologic yield in diagnostic cohorts. These findings may facilitate clinical decision making and guide clinical research into novel biomarkers of TB disease in young children. |
Retaining patients with drug-resistant tuberculosis on treatment during the COVID-19 pandemic - Dharavi, Mumbai, India, 2020-2022
Gomare MD , Bhide S , Deshmukh R , Kaipilyawar S , Puri V , Moonan PK , Khetade DK , Nyendak M , Yeldandi V , Smith JP , Tobias JL , Date A , Joshi R , Kumar R , Ho CS . MMWR Morb Mortal Wkly Rep 2023 72 (12) 304-308 Mumbai, India's second largest city, has one of the highest prevalences of drug-resistant tuberculosis* (DRTB) in the world. Treatment for DRTB takes longer and is more complicated than treatment for drug-susceptible tuberculosis (TB). Approximately 300 persons receive a new DRTB diagnosis each year in Mumbai's Dharavi slum(†); historically, fewer than one half of these patients complete DRTB treatment. As nationwide restrictions to mitigate the COVID-19 pandemic were implemented, a program to facilitate uninterrupted DRTB care for patients receiving treatment was also implemented. A comprehensive tool and risk assessment provided support to DRTB patients and linked those who relocated outside of Dharavi during the pandemic to DRTB care at their destination. During May 2020-September 2022, a total of 973 persons received DRTB treatment in Dharavi, including 255 (26%) who relocated during treatment. Overall, 25 (3%) DRTB patients were lost to follow-up, a rate substantially lower than the rate before the pandemic (18%). Proactive planning and implementation of simple tools retained patients on treatment during periods of travel restrictions and relocations, improving programmatic outcomes. This approach might aid public health programs serving migrant populations or patients receiving treatment for DRTB during public health emergencies. |
Prenatal syphilis screening among pregnant Medicaid enrollees by sexually transmitted infection history and race/ethnicity
Hammerslag LR , Campbell-Baier RE , Otter CA , López-De Fede A , Smith JP , Whittington LA , Humble LJ , Myers ER , Kennedy SR , Talbert JC , Pearson WS . Am J Obstet Gynecol MFM 2023 5 (6) 100937 BACKGROUND: Congenital syphilis can cause severe morbidity, including miscarriage and stillbirth, and rates are increasing rapidly within the United States. However, congenital syphilis can be prevented with early detection and treatment of syphilis during pregnancy. Current screening recommendations propose that all women should be screened early in pregnancy, whereas women with elevated risks for congenital syphilis should be screened again later in pregnancy. The rapid increase in congenital syphilis rates suggests that there are still gaps in prenatal syphilis screening. OBJECTIVE: This study aimed to examine associations between the odds of prenatal syphilis screening and sexually transmitted infection history or other patient characteristics across 3 states with elevated rates of congenital syphilis. STUDY DESIGN: We used the Medicaid claims data from Kentucky, Louisiana, and South Carolina for women with deliveries between 2017 and 2021. Within each state, we examined the log-odds of prenatal syphilis screening as a function of the mother's health history, demographic factors, and Medicaid enrollment history. Patient history was established using a 4-year lookback period of the Medicaid claims data; in state A, sexually transmitted infection surveillance data were used to improve the sexually transmitted infection history. RESULTS: The prenatal syphilis screening rates varied by state, ranging from 62.8% to 85.1% of deliveries to women without a recent history of sexually transmitted infections and from 78.1% to 91.1% of deliveries to women with a previous sexually transmitted infection. For the main outcome of syphilis screening at any time during pregnancy, deliveries associated with previous sexually transmitted infections had 1.09 to 1.37 times higher adjusted odds ratios of undergoing screening. Deliveries to women with continuous Medicaid coverage throughout the first trimester also had higher odds of syphilis screening at any time (adjusted odds ratio, 2.45-3.15). Among deliveries to women with a previous sexually transmitted infection, only 53.6% to 63.6% underwent first-trimester screening and this rate was still just 55.0% to 69.5% when considering only deliveries to women with a previous sexually transmitted infection and full first-trimester Medicaid coverage. Fewer delivering women underwent third-trimester screening (20.3%-55.8% of women with previous sexually transmitted infection). Compared with deliveries to White women, deliveries to Black women had lower odds of first-trimester screening (adjusted odds ratio, 0.85 in all states) but higher odds of third-trimester screening (adjusted odds ratio, 1.23-2.03), potentially impacting maternal and birth outcomes. For state A, linkage to surveillance data doubled the rate of detection of a previous sexually transmitted infection because 53.0% of deliveries by women with a previous sexually transmitted infection would not have had sexually transmitted infection history detected using Medicaid claims alone. CONCLUSION: A previous sexually transmitted infection and continuous preconception Medicaid enrollment were associated with higher rates of syphilis screening, but Medicaid claims alone do not fully capture the sexually transmitted infection history of patients. The overall screening rates were lower than would be expected given that all women should undergo prenatal screening, but the rates in the third trimester were particularly low. Of note, there are gaps in early screening for non-Hispanic Black women who had lower odds of first-trimester screening when compared with non-Hispanic White women despite being at elevated risk for syphilis. |
Isolation and quarantine for COVID-19 in the United States, 2020-2022
Oeltmann JE , Vohra D , Matulewicz HH , DeLuca N , Smith JP , Couzens C , Lash RR , Harvey B , Boyette M , Edwards A , Talboy PM , Dubose O , Regan P , Loosier P , Caruso E , Katz DJ , Taylor MM , Moonan PK . Clin Infect Dis 2023 77 (2) 212-219 BACKGROUND: Public health programs varied in ability to reach people with COVID-19 and their contacts to encourage separation from others. For both adult cases of COVID-19 and contacts, we estimated the impact of contact tracing activities on separation behaviors from January, 2020 until March, 2022. METHODS: We used a probability-based panel survey of a nationally representative sample to gather data for estimates and comparisons. RESULTS: An estimated 64,255,351 adults reported a positive SARS-CoV-2 test result; 79.6% isolated for >5 days, 60.2% isolated for >10 days, and 79.2% self-notified contacts. 24,057,139 (37.7%) completed a case investigation and 46.2% reported contacts to health officials. More adults who completed a case investigation isolated than adults who did not (>5 days, 82.6%; >10 days, 69.8% versus >5 days, 78.2% and >10 days 54.8%; p-values for both measures <0.05).84,946,636 adults were a contact to a COVID-19 case; 73.1% learned of their exposure directly from a case; 49.4% quarantined for >5 days, 18.7% quarantined for >14 days, and 13.5% completed a contact tracing call. More who completed a contact tracing call quarantined than those who did not (>5 days, 61.2%; >14 days, 25.2% versus >5 days, 48.5%; >14 days, 18.0%; p-values for both measures <0.05). CONCLUSIONS: Engagement in contact tracing positively correlated with isolation and quarantine. However, most adults with COVID-19 isolated and self-notified contacts regardless of whether the public health workforce was able to reach them. Identifying and reaching contacts was challenging, and limited the ability to promote quarantining, and testing. |
Development of treatment-decision algorithms for children evaluated for pulmonary tuberculosis: an individual participant data meta-analysis.
Gunasekera KS , Marcy O , Muñoz J , Lopez-Varela E , Sekadde MP , Franke MF , Bonnet M , Ahmed S , Amanullah F , Anwar A , Augusto O , Aurilio RB , Banu S , Batool I , Brands A , Cain KP , Carratalá-Castro L , Caws M , Click ES , Cranmer LM , García-Basteiro AL , Hesseling AC , Huynh J , Kabir S , Lecca L , Mandalakas A , Mavhunga F , Myint AA , Myo K , Nampijja D , Nicol MP , Orikiriza P , Palmer M , Sant'Anna CC , Siddiqui SA , Smith JP , Song R , Thuong Thuong NT , Ung V , van der Zalm MM , Verkuijl S , Viney K , Walters EG , Warren JL , Zar HJ , Marais BJ , Graham SM , Debray TPA , Cohen T , Seddon JA . Lancet Child Adolesc Health 2023 7 (5) 336-346 BACKGROUND: Many children with pulmonary tuberculosis remain undiagnosed and untreated with related high morbidity and mortality. Recent advances in childhood tuberculosis algorithm development have incorporated prediction modelling, but studies so far have been small and localised, with limited generalisability. We aimed to evaluate the performance of currently used diagnostic algorithms and to use prediction modelling to develop evidence-based algorithms to assist in tuberculosis treatment decision making for children presenting to primary health-care centres. METHODS: For this meta-analysis, we identified individual participant data from a WHO public call for data on the management of tuberculosis in children and adolescents and referral from childhood tuberculosis experts. We included studies that prospectively recruited consecutive participants younger than 10 years attending health-care centres in countries with a high tuberculosis incidence for clinical evaluation of pulmonary tuberculosis. We collated individual participant data including clinical, bacteriological, and radiological information and a standardised reference classification of pulmonary tuberculosis. Using this dataset, we first retrospectively evaluated the performance of several existing treatment-decision algorithms. We then used the data to develop two multivariable prediction models that included features used in clinical evaluation of pulmonary tuberculosis-one with chest x-ray features and one without-and we investigated each model's generalisability using internal-external cross-validation. The parameter coefficient estimates of the two models were scaled into two scoring systems to classify tuberculosis with a prespecified sensitivity target. The two scoring systems were used to develop two pragmatic, treatment-decision algorithms for use in primary health-care settings. FINDINGS: Of 4718 children from 13 studies from 12 countries, 1811 (38·4%) were classified as having pulmonary tuberculosis: 541 (29·9%) bacteriologically confirmed and 1270 (70·1%) unconfirmed. Existing treatment-decision algorithms had highly variable diagnostic performance. The scoring system derived from the prediction model that included clinical features and features from chest x-ray had a combined sensitivity of 0·86 [95% CI 0·68-0·94] and specificity of 0·37 [0·15-0·66] against a composite reference standard. The scoring system derived from the model that included only clinical features had a combined sensitivity of 0·84 [95% CI 0·66-0·93] and specificity of 0·30 [0·13-0·56] against a composite reference standard. The scoring system from each model was placed after triage steps, including assessment of illness acuity and risk of poor tuberculosis-related outcomes, to develop treatment-decision algorithms. INTERPRETATION: We adopted an evidence-based approach to develop pragmatic algorithms to guide tuberculosis treatment decisions in children, irrespective of the resources locally available. This approach will empower health workers in primary health-care settings with high tuberculosis incidence and limited resources to initiate tuberculosis treatment in children to improve access to care and reduce tuberculosis-related mortality. These algorithms have been included in the operational handbook accompanying the latest WHO guidelines on the management of tuberculosis in children and adolescents. Future prospective evaluation of algorithms, including those developed in this work, is necessary to investigate clinical performance. FUNDING: WHO, US National Institutes of Health. |
High-Resolution Characterization of Nosocomial Mycobacterium tuberculosis Transmission Events in Botswana.
Smith JP , Modongo C , Oeltmann JE , Dima M , Matsiri O , Fane O , Molefi T , Shin SS , Barilar I , Niemann S , Zetola NM , Moonan PK . Am J Epidemiol 2022 192 (3) 503-506 Introduction: Tuberculosis (TB) remains a leading cause of preventable morbidity and mortality, with an estimated 10.6 million new cases and 1.6 million deaths globally in 2021 (1). Nosocomial transmission of Mycobacterium tuberculosis, the etiologic agent responsible for TB disease, is a major public health concern. This is particularly true for high-prevalence, low-resource settings where the majority of the global TB burden exists (2–6). Interventions to reduce nosocomial transmission require a clear understanding of where TB spreads in health-care facilities. |
Clinical and radiologic factors associated with detection of mycobacterium tuberculosis in children under 5years old using invasive and noninvasive sample collection techniques-Kenya
Smith JP , Song R , McCarthy KD , McHembere W , Click ES , Cain KP . Open Forum Infect Dis 2022 9 (11) ofac560 BACKGROUND: Pediatric tuberculosis (TB) remains a critical public health concern, yet bacteriologic confirmation of TB in children is challenging. Clinical, demographic, and radiological factors associated with a positive Mycobacterium tuberculosis specimen in young children (5years) are poorly understood. METHODS: We conducted a prospective cohort study of young children with presumptive TB and examined clinical, demographic, and radiologic factors associated with invasive and noninvasive specimen collection techniques (gastric aspirate, induced sputum, nasopharyngeal aspirate, stool, and string test); up to 2 samples were taken per child, per technique. We estimated associations between these factors and a positive specimen for each technique using generalized estimating equations (GEEs) and logistic regression. RESULTS: A median (range) of 544 (507-566) samples were obtained for each specimen collection technique from 300 enrolled children; bacteriologic yield was low across all collection techniques (range, 1%-7% from Xpert MTB/RIF or culture), except for lymph node fine needle aspiration (29%) taken for children with cervical lymphadenopathy. Factors associated with positive M. tuberculosis samples across all techniques included prolonged lethargy (median [range] adjusted odds ratio [aOR], 8.1 [3.9-10.1]), history of exposure with a TB case (median [range] aOR, 6.1 [2.9-9.0]), immunologic evidence of M. tuberculosis infection (median [range] aOR, 4.6 [3.7-9.2]), large airway compression (median [range] aOR, 6.7 [4.7-9.5]), and hilar/mediastinal density (median [range] aOR, 2.9 [1.7-3.2]). CONCLUSIONS: Identifying factors that lead to a positive M. tuberculosis specimen in very young children can inform clinical management and increase the efficiency of diagnostic testing in children being assessed for TB. |
Performance of Xpert MTB/RIF and mycobacterial culture on multiple specimen types for diagnosis of tuberculosis disease in young children and clinical characterization according to standardized research case definitions
Click ES , Song R , Smith JP , McHembere W , Fajans M , Hariri P , Okeyo E , McCarthy KD , Gethi D , Odeny L , Musau S , Okumu A , Orwa J , Perez-Velez CM , Wright CA , Andres MM , Marais BJ , Schaaf HS , Graham SM , Cruz AT , Cain KP . Pediatr Infect Dis J 2022 41 (8) 671-677 BACKGROUND: Tuberculosis (TB) is a leading cause of illness and death in children globally. Improved bacteriologic and clinical diagnostic approaches in children are urgently needed. METHODS: In a prospective cohort study, a consecutive series of young (<5 years) children presenting with symptoms suggestive of TB and parenchymal abnormality on chest radiograph in inpatient and outpatient settings in Kisumu County, Kenya from October 2013 to August 2015 were evaluated at baseline and over 6 months. Up to 14 specimens per child were tested for the Mycobacterium tuberculosis complex by fluorescence microscopy, Xpert MTB/RIF and mycobacterial culture. Using detailed clinical characterization, cases were retrospectively classified according to standardized research case definitions and the sensitivity and specificity of microbiological tests on different specimen types were determined. RESULTS: Among 300 young children enrolled, 266 had sufficient information to be classified according to the research clinical case definition. Of these, 36% (96/266) had TB disease; 32% (31/96) with bacteriologically confirmed intrathoracic TB. Compared to culture, the sensitivity of a single Xpert test ranged from 60 to 67% and specificity from 97.5 to 100% for different specimen types. CONCLUSIONS: Despite extensive specimen collection and laboratory testing, TB could not be bacteriologically confirmed in almost two-thirds of children with intrathoracic TB classified by research clinical case definitions. Improved diagnostic tests are needed to identify children with TB and to exclude other potential causes of illness. |
Characterizing tuberculosis transmission dynamics in high-burden urban and rural settings.
Smith JP , Oeltmann JE , Hill AN , Tobias JL , Boyd R , Click ES , Finlay A , Mondongo C , Zetola NM , Moonan PK . Sci Rep 2022 12 (1) 6780 Mycobacterium tuberculosis transmission dynamics in high-burden settings are poorly understood. Growing evidence suggests transmission may be characterized by extensive individual heterogeneity in secondary cases (i.e., superspreading), yet the degree and influence of such heterogeneity is largely unknown and unmeasured in high burden-settings. We conducted a prospective, population-based molecular epidemiology study of TB transmission in both an urban and rural setting of Botswana, one of the highest TB burden countries in the world. We used these empirical data to fit two mathematical models (urban and rural) that jointly quantified both the effective reproductive number, [Formula: see text], and the propensity for superspreading in each population. We found both urban and rural populations were characterized by a high degree of individual heterogeneity, however such heterogeneity disproportionately impacted the rural population: 99% of secondary transmission was attributed to only 19% of infectious cases in the rural population compared to 60% in the urban population and the median number of incident cases until the first outbreak of 30 cases was only 32 for the rural model compared to 791 in the urban model. These findings suggest individual heterogeneity plays a critical role shaping local TB epidemiology within subpopulations. |
Zambia assessment of tuberculosis (TB) and HIV in the mines (ZATHIM): implications for programs and policies
Podewils LJ , Long EF , Fuller TJ , Mwakazanga D , Kapungu K , Tembo M , Mwanza S , Curran KG , Smith JP , Tobias JL , Kasongo W . BMC Public Health 2022 22 (1) 791 BACKGROUND: Mineworkers in Southern Africa have the highest rates of tuberculosis (TB) among working populations in the world (The World Bank, Benefits and costs associated with reducing tuberculosis among Southern Africa's mineworkers, 2014), making mineworkers a key population for TB program efforts. The current evaluation aimed to characterize mineworkers and former (ex-) mineworkers, and assess knowledge, attitudes and practices related to TB and HIV care among mineworkers and healthcare workers (HCWs) in Zambia. METHODS: A mixed-methods evaluation of current and former (ex-) mineworkers and HCWs was conducted in the Copperbelt and North-Western provinces, Zambia. Knowledge, attitudes and practices (KAPs) related to TB care and policies were assessed using a structured survey. Focus Group Discussions (FGDs) were conducted with current and ex-mineworkers to understand perceptions, practices, and barriers related to accessing healthcare for TB. RESULTS: Overall, 2,792 mineworkers and 94 HCWs completed the KAP survey, and 206 (171 current, 71 ex-) mineworkers participated in FGDs. Mineworkers and ex-mineworkers were knowledgeable about TB symptoms (cough; 94%), transmission (81.7%) and treatment (99.2%). Yet, barriers to seeking care were evident with 30% of mineworkers experiencing cough, and 19% reporting 2 or more TB symptoms at the time of the survey. The majority of mineworkers (70.9%) were aware of policies barring persons from working after a diagnosis of TB, and themes from FGDs and HCW comments (n = 32/62; 51.6%) recognized fear of job loss as a critical barrier to providing timely screening and appropriate care for TB among mineworkers. The majority (76.9%) of mineworkers indicated they would not disclose their TB status to their supervisor, but would be willing to share their diagnosis with their spouse (73.8%). CONCLUSION: Fear of job loss, driven by governmental policy and mistrust in mining companies, is a major barrier to healthcare access for TB among mineworkers in Zambia. As a result of these findings, the government policy prohibiting persons from working in the mines following TB disease is being repealed. However, major reforms are urgently needed to mitigate TB among mineworkers, including ensuring the rights of mineworkers and their communities to healthy living and working environments, improved social responsibility of mining companies, and facilitating choice and access to affordable, timely, and high-quality healthcare services. |
Tuberculosis attributed to transmission within healthcare facilities, Botswana-The Kopanyo Study.
Smith JP , Modongo C , Moonan PK , Dima M , Matsiri O , Fane O , Click ES , Boyd R , Finlay A , Surie D , Tobias JL , Zetola NM , Oeltmann JE . Infect Control Hosp Epidemiol 2022 43 (11) 1-7 OBJECTIVE: Healthcare facilities are a well-known high-risk environment for transmission of M. tuberculosis, the etiologic agent of tuberculosis (TB) disease. However, the link between M. tuberculosis transmission in healthcare facilities and its role in the general TB epidemic is unknown. We estimated the proportion of overall TB transmission in the general population attributable to healthcare facilities. METHODS: We combined data from a prospective, population-based molecular epidemiologic study with a universal electronic medical record (EMR) covering all healthcare facilities in Botswana to identify biologically plausible transmission events occurring at the healthcare facility. Patients with M. tuberculosis isolates of the same genotype visiting the same facility concurrently were considered an overlapping event. We then used TB diagnosis and treatment data to categorize overlapping events into biologically plausible definitions. We calculated the proportion of overall TB cases in the cohort that could be attributable to healthcare facilities. RESULTS: In total, 1,881 participants had TB genotypic and EMR data suitable for analysis, resulting in 46,853 clinical encounters at 338 healthcare facilities. We identified 326 unique overlapping events involving 370 individual patients; 91 (5%) had biologic plausibility for transmission occurring at a healthcare facility. A sensitivity analysis estimated that 3%-8% of transmission may be attributable to healthcare facilities. CONCLUSIONS: Although effective interventions are critical in reducing individual risk for healthcare workers and patients at healthcare facilities, our findings suggest that development of targeted interventions aimed at community transmission may have a larger impact in reducing TB. |
A Cluster-based Method to Quantify Individual Heterogeneity in Tuberculosis Transmission.
Smith JP , Gandhi NR , Silk BJ , Cohen T , Lopman B , Raz K , Winglee K , Kammerer S , Benkeser D , Kramer M , Hill AN . Epidemiology 2021 33 (2) 217-227 BACKGROUND: Recent evidence suggests transmission of Mycobacterium tuberculosis (Mtb) may be characterized by extreme individual heterogeneity in secondary cases (i.e., few cases account for the majority of transmission). Such heterogeneity implies outbreaks are rarer but more extensive and has profound implications in infectious disease control. However, discrete person-to-person transmission events in TB are often unobserved, precluding our ability to directly quantify individual heterogeneity in TB epidemiology. METHODS: We used a modified negative binomial branching process model to quantify the extent of individual heterogeneity using only observed transmission cluster size distribution data (i.e., the simple sum of all cases in a transmission chain) without knowledge of individual-level transmission events. The negative binomial parameter k quantifies the extent of individual heterogeneity (generally, k<1 indicates extensive heterogeneity, and as k→∞ transmission becomes more homogenous). We validated the robustness of the inference procedure considering common limitations affecting cluster-size data. Finally, we demonstrate the epidemiologic utility of this method by applying it to aggregate United States molecular surveillance data from the U.S. Centers for Disease Control and Prevention. RESULTS: The cluster-based method reliably inferred k using TB transmission cluster data despite a high degree of bias introduced into the model. We found that the TB transmission in the United States was characterized by a high propensity for extensive outbreaks (k=0.09; 95% confidence interval: 0.09, 0.10). CONCLUSION: The proposed method can accurately quantify critical parameters that govern TB transmission using simple, more easily obtainable cluster data to improve our understanding of TB epidemiology. |
Sensitive and feasible specimen collection and testing strategies for diagnosing tuberculosis in young children
Song R , Click ES , McCarthy KD , Heilig CM , McHembere W , Smith JP , Fajans M , Musau SK , Okeyo E , Okumu A , Orwa J , Gethi D , Odeny L , Lee SH , Perez-Velez CM , Wright CA , Cain KP . JAMA Pediatr 2021 175 (5) e206069 IMPORTANCE: Criterion-standard specimens for tuberculosis diagnosis in young children, gastric aspirate (GA) and induced sputum, are invasive and rarely collected in resource-limited settings. A far less invasive approach to tuberculosis diagnostic testing in children younger than 5 years as sensitive as current reference standards is important to identify. OBJECTIVE: To characterize the sensitivity of preferably minimally invasive specimen and assay combinations relative to maximum observed yield from all specimens and assays combined. DESIGN, SETTING, AND PARTICIPANTS: In this prospective cross-sectional diagnostic study, the reference standard was a panel of up to 2 samples of each of 6 specimen types tested for Mycobacterium tuberculosis complex by Xpert MTB/RIF assay and mycobacteria growth indicator tube culture. Multiple different combinations of specimens and tests were evaluated as index tests. A consecutive series of children was recruited from inpatient and outpatient settings in Kisumu County, Kenya, between October 2013 and August 2015. Participants were children younger than 5 years who had symptoms of tuberculosis (unexplained cough, fever, malnutrition) and parenchymal abnormality on chest radiography or who had cervical lymphadenopathy. Children with 1 or more evaluable specimen for 4 or more primary study specimen types were included in the analysis. Data were analyzed from February 2015 to October 2020. MAIN OUTCOMES AND MEASURES: Cumulative and incremental diagnostic yield of combinations of specimen types and tests relative to the maximum observed yield. RESULTS: Of the 300 enrolled children, the median (interquartile range) age was 2.0 (1.0-3.6) years, and 151 (50.3%) were female. A total of 294 met criteria for analysis. Of 31 participants with confirmed tuberculosis (maximum observed yield), 24 (sensitivity, 77%; interdecile range, 68%-87%) had positive results on up to 2 GA samples and 20 (sensitivity, 64%; interdecile range, 53%-76%) had positive test results on up to 2 induced sputum samples. The yields of 2 nasopharyngeal aspirate (NPA) samples (23 of 31 [sensitivity, 74%; interdecile range, 64%-84%]), of 1 NPA sample and 1 stool sample (22 of 31 [sensitivity, 71%; interdecile range, 60%-81%]), or of 1 NPA sample and 1 urine sample (21.5 of 31 [sensitivity, 69%; interdecile range, 58%-80%]) were similar to reference-standard specimens. Combining up to 2 each of GA and NPA samples had an average yield of 90% (28 of 31). CONCLUSIONS AND RELEVANCE: NPA, in duplicate or in combination with stool or urine specimens, was readily obtainable and had diagnostic yield comparable with reference-standard specimens. This combination could improve tuberculosis diagnosis among children in resource-limited settings. Combining GA and NPA had greater yield than that of the current reference standards and may be useful in certain clinical and research settings. |
The impact of concurrent antiretroviral therapy and MDR-TB treatment on adverse events
Smith JP , Gandhi NR , Shah NS , Mlisana K , Moodley P , Johnson BA , Allana S , Campbell A , Nelson KN , Master I , Brust JCM . J Acquir Immune Defic Syndr 2020 83 (1) 47-55 BACKGROUND: South Africa has among the highest incidence of multidrug-resistant tuberculosis (MDR-TB) and more than 70% of patients are HIV co-infected. MDR-TB treatment is associated with frequent adverse events (AEs). Although guidelines recommend concurrent treatment of MDR-TB and HIV, safety data on concurrent therapy are limited. METHODS: We conducted a prospective observational study of MDR-TB patients with and without HIV-coinfection in South Africa between 2011 and 2015. Participants received standardized MDR-TB and HIV regimens. Participants were followed monthly for the duration of MDR-TB therapy and screened for clinical and laboratory AEs. Audiometry was performed monthly during the intensive phase; color discrimination testing was performed every 2 months. RESULTS: We enrolled 150 HIV-infected and 56 HIV-uninfected participants. Nearly all experienced at least one clinical (93%) or laboratory (96%) AE. The most common clinical AEs were peripheral neuropathy (50%) and difficulty sleeping (48%); the most common laboratory AEs were hypokalemia (47%) and decreased creatinine clearance (46%). Among 19 clinical and lab AEs examined, there were no differences by HIV status, except for diarrhea (27% HIV-infected vs. 13% HIV-uninfected, P = 0.03). Hearing loss was experienced by 72% of participants (8% severe loss). Fourteen percent experienced color discrimination loss (4% severe loss). There were no differences in frequency or severity of hearing or vision loss by HIV status. CONCLUSIONS: AEs were common, but not more frequent or severe among MDR-TB/HIV co-infected participants receiving concurrent antiretroviral therapy. Given the favorable treatment outcomes associated with concurrent treatment, antiretroviral therapy initiation should not be delayed in MDR-TB patients with HIV-coinfection. |
Field evaluation of onsite near real-time monitors for surface contamination by 5-fluorouracil
Smith JP , Sammons D , Robertson S , Krieg E , Snawder J . J Oncol Pharm Pract 2018 25 (5) 1152-1159 Objectives In order to produce near real-time onsite results to detect surface contamination by antineoplastic drugs, the National Institute for Occupational Safety and Health developed monitors for 5-fluorouracil, which use surface wiping and lateral flow immunoassay for measurement. The monitors were tested in the laboratory to assess the sensitivity of detection on laboratory-produced contaminated surfaces. A field evaluation to assess the capability of the monitors to make measurements in healthcare workplaces was carried out in collaboration with a medical device company and the results are presented in this report. Methods The 5-fluorouracil monitor was evaluated in areas where oncology drugs were prepared and administered to patients at five different hospitals. The levels of contamination measured with the monitors were compared to levels measured with liquid chromatography-tandem mass spectrometry. Results The 5-fluorouracil values measured with the liquid chromatography-tandem mass spectrometry ranged from 0 to over 200,000 ng/100 cm(2). Measurements by the 5-fluorouracil monitors in the range 10-100 ng/100 cm(2) correlated with the liquid chromatography-tandem mass spectrometry. Receiver operating characteristic curves developed for the data indicated that a positive limit of 22 ng/100 cm(2) would give an acceptable level of false-positives while retaining most true-positive samples. If the liquid chromatography-tandem mass spectrometry measured greater than 100 ng/100 cm(2), then the monitors also measured levels greater than 100 ng/100 cm(2) for the majority of samples. Conclusion The data indicate that there are many areas in hospitals that are contaminated with 5-fluorouracil and the monitors will be useful in identifying this contamination. |
Improved survival and cure rates with concurrent treatment for MDR-TB/HIV co-infection in South Africa
Brust JCM , Shah NS , Mlisana K , Moodley P , Allana S , Campbell A , Johnson BA , Master I , Mthiyane T , Lachman S , Larkan LM , Ning Y , Malik A , Smith JP , Gandhi NR . Clin Infect Dis 2017 66 (8) 1246-1253 Background: The global epidemic of multidrug-resistant tuberculosis (MDR-TB) threatens gains in TB and HIV outcomes over the past two decades. Mortality in MDR-TB/HIV co-infection has historically been high, but most studies predated the availability of antiretroviral therapy (ART). We prospectively compared survival and treatment outcomes in MDR-TB/HIV co-infected patients on ART to those in patients with MDR-TB alone. Methods: This prospective, observational study enrolled culture-confirmed MDR-TB patients, with and without HIV co-infection, in South Africa between 2011-2013. Participants received standardized MDR-TB and HIV regimens and were followed monthly for treatment response, adverse events, and adherence. The primary outcome was survival. Results: Among 206 participants, 150 were HIV-infected, 131 (64%) were female, and the median age was 33 years (IQR 26-41). Of the 191 participants with a final MDR-TB outcome, 130 (73%) were cured or successfully completed treatment, which did not differ by HIV status (p=0.50). After two years, the median CD4 count was 386 cells/mm3 (IQR 219-510), an increase of 140 cells/mm3 from baseline (p=0.005), and 64% had an undetectable HIV viral load. HIV-infected and HIV-uninfected participants had high rates of survival (86% and 94%, respectively; p=0.34). The strongest risk factor for mortality was having a CD4 count </=100 cells/mm3 (aHR 15.6, 95%CI 4.4-55.6). Conclusions: Survival and treatment outcomes among MDR-TB/HIV individuals receiving concurrent ART were improved, approaching those of HIV-uninfected MDR-TB patients. The greatest risk of death was among HIV-infected individuals with CD4 counts </=100 cells/mm3. These findings provide critical evidence to support concurrent treatment of MDR-TB and HIV. |
Enhanced performance of methamphetamine lateral flow cassettes using an electronic lateral flow reader
Smith JP , Sammons DL , Robertson SA , Snawder JE . J Occup Environ Hyg 2015 12 (1) 45-50 Surface contamination from methamphetamine in meth labs continues to be a problem. We had previously developed a lateral flow assay cassette for field detection of methamphetamine contamination that is commercially available and has been used by a number of groups to assess contamination. This cassette uses the complete disappearance of the test line as an end point for detection of 50 ng/100 cm2 of methamphetamine contamination for surface sampling with cotton swabs. In the present study, we further evaluate the response of the cassettes using an electronic lateral flow reader to measure the intensities of the test and control lines. The cassettes were capable of detecting 0.25 ng/ml for calibration solutions. For 100 cm2 ceramic tiles that were spiked with methamphetamine and wiped with cotton-tipped wooden swabs wetted in assay/sampling buffer, 1 ng/tile was detected using the reader. Semi-quantitative results can be produced over the range 0-10 ng/ml for calibration solutions and 0-25 ng/tile for spiked tiles using either a 4-parameter logistic fit of test line intensity versus concentration or spiked mass or the ratio of the control line to the test line intensity fit to concentration or spiked mass. Recovery from the tiles was determined to be about 30% using the fitted curves. Comparison of the control line to the test line was also examined as a possible visual detection end point and it was found that the control line became more intense than the test line at 0.5 to 1 ng/ml for calibration solutions or 1 to 2 ng/tile for spiked tiles. Thus the lateral flow cassettes for methamphetamine have the potential to produce more sensitive semi-quantitative results if an electronic lateral flow reader is used and can be more sensitive for detection if the comparison of the control line to the test line is used as the visual end point. |
Detection of 5-fluorouracil surface contamination in near real time
Smith JP , Sammons DL , Pretty JR , Kurtz KS , Robertson SA , DeBord DG , Connor TH , Snawder JE . J Oncol Pharm Pract 2015 22 (3) 396-408 OBJECTIVES: Contamination of workplace surfaces by antineoplastic drugs presents an exposure risk for healthcare workers. Traditional instrumental methods to detect contamination such as gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS) are sensitive and accurate but expensive and incapable of producing results in real time. This limits their utility in preventing worker exposure. We are currently developing monitors based on lateral flow immunoassay that can detect drug contamination in near real time. In this report, we describe the laboratory performance of a 5-fluorouracil (5-FU) monitor. METHODS: The monitor was evaluated by spiking ceramic, vinyl, composite, stainless steel, and glass surfaces of 100 cm2 area with 5-FU masses of 0, 5, 10, 25, 50, and 100 ng. The surface was sampled with a wetted cotton swab, the swab was extracted with buffer, and the resulting solution was applied to a lateral flow monitor. Two ways of evaluating the response of these monitors were used: an electronic method where a lateral flow reader was used for measuring line intensities, and a visual method where the intensity of the test line was visually compared to the control line. RESULTS: The 5-FU monitor is capable of detecting 10 ng/100 cm2 (0.1 ng/cm2) using the electronic reader and 25 ng/100 cm2 (0.25 ng/cm2) using the visual comparison method for the surfaces studied. The response of the monitors was compared to LC-MS/MS results for the same samples for validation and there was good correlation of the two methods but some differences in absolute response, especially at higher spiking levels for the surface samples. |
Detection and measurement of surface contamination by multiple antineoplastic drugs using multiplex bead assay
Smith JP , Sammons DL , Robertson SA , Pretty JR , DeBord DG , Connor TH , Snawder JE . J Oncol Pharm Pract 2014 22 (1) 60-7 OBJECTIVES: Contamination of workplace surfaces by antineoplastic drugs presents an exposure risk for healthcare workers. Traditional instrumental methods to detect contamination such as liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) are sensitive and accurate but expensive. Since immunochemical methods may be cheaper and faster than instrumental methods, we wanted to explore their use for routine drug residue detection for preventing worker exposure. METHODS: In this study we examined the feasibility of using fluorescence covalent microbead immunosorbent assay (FCMIA) for simultaneous detection and semi-quantitative measurement of three antineoplastic drugs (5-fluorouracil, paclitaxel, and doxorubicin). The concentration ranges for the assay were 0-1000 ng/ml for 5-fluorouracil, 0-100 ng/ml for paclitaxel, and 0-2 ng/ml for doxorubicin. The surface sampling technique involved wiping a loaded surface with a swab wetted with wash buffer, extracting the swab in storage/blocking buffer, and measuring drugs in the extract using FCMIA. RESULTS: There was no significant cross-reactivity between these drugs at the ranges studied indicated by a lack of response in the assay to cross analytes. The limit of detection (LOD) for 5-fluorouracil on the surface studied was 0.93 ng/cm2 with a limit of quantitation (LOQ) of 2.8 ng/cm2, the LOD for paclitaxel was 0.57 ng/cm2 with an LOQ of 2.06 ng/cm2, and the LOD for doxorubicin was 0.0036 ng/cm2 with an LOQ of 0.013 ng/cm2. CONCLUSION: The use of FCMIA with a simple sampling technique has potential for low cost simultaneous detection and semi-quantitative measurement of surface contamination from multiple antineoplastic drugs. |
Using urinary biomarkers of polycyclic aromatic compound exposure to guide exposure-reduction strategies among asphalt paving workers
McClean MD , Osborn LV , Snawder JE , Olsen LD , Kriech AJ , Sjodin A , Li Z , Smith JP , Sammons DL , Herrick RF , Cavallari JM . Ann Occup Hyg 2012 56 (9) 1013-24 INTRODUCTION: Paving workers are exposed to polycyclic aromatic compounds (PACs) while working with hot-mix asphalt (HMA). Further characterization of the source and route of these exposures is necessary to guide exposure-reduction strategies. METHODS: Personal air (n = 144), hand-wash (n = 144), and urine (n = 480) samples were collected from 12 paving workers over 3 workdays during 4 workweeks. Urine samples were collected at preshift, postshift, and bedtime and analyzed for 10 hydroxylated PACs (1-OH-pyrene; 1-, 2-, 3-, 4-OH-phenanthrene; 1-, 2-OH-naphthalene; 2-, 3-, 9-OH-fluorene) by an immunochemical quantification of PACs (I-PACs). The air and hand-wash samples were analyzed for the parent compounds corresponding to the urinary analytes. Using a crossover study design, each of the 4 weeks represented a different exposure scenario: a baseline week (normal conditions), a dermal protection week (protective clothing), a powered air-purifying respirator (PAPR) week, and a biodiesel substitution week (100% biodiesel provided to replace the diesel oil normally used by workers to clean tools and equipment). The urinary analytes were analyzed using linear mixed-effects models. RESULTS: Postshift and bedtime concentrations were significantly higher than preshift concentrations for most urinary biomarkers. Compared with baseline, urinary analytes were reduced during the dermal protection (29% for 1-OH-pyrene, 15% for I-PACs), the PAPR (24% for 1-OH-pyrene, 15% for I-PACs), and the biodiesel substitution (15% for 1-OH-pyrene) weeks. The effect of PACs in air was different by exposure scenario (biodiesel substitution > dermal protection > PAPR and baseline) and was still a significant predictor of most urinary analytes during the week of PAPR use, suggesting that PACs in air were dermally absorbed. The application temperature of HMA was positively associated with urinary measures, such that an increase from the lowest application temperature (121 degrees C) to the highest (154 degrees C) was associated with a 72% increase in SigmaOH-fluorene and 1-OH-pyrene and an 82% increase in SigmaOH-phenanthrene. Though PACs in hand-wash samples were not predictors of urinary analytes, the effects observed during the PAPR scenario and the week of increased dermal protection provide evidence of dermal absorption. CONCLUSIONS: Our results provide evidence that PACs in air are dermally absorbed. Reducing the application temperature of asphalt mix appears to be a promising strategy for reducing PAC exposure among paving workers. Additional reductions may be achieved by requiring increased dermal coverage of workers and by substituting biodiesel for diesel oil as a cleaning agent. |
Assessment of exposure to PACs in asphalt workers: measurement of urinary PACs and their metabolites with an ELISA kit
Smith JP , Biagini RE , Johnson BC , Olsen LD , Mackenzie BA , Robertson SA , Sammons DL , Striley CAF , Walker CV , Snawder JE . Polycycl Aromat Compd 2011 31 (4) 270-285 An enzyme-linked immunosorbent assay (ELISA) kit made for determination of polycyclic aromatic compounds (PACs) in water was adapted for measuring PACs and their metabolites in urine. This method was then applied to a pilot asphalt worker PAC exposure study. Currently, liquid-liquid extraction with gas chromatography/isotope dilution high-resolution mass spectrometry (GC/HRMS) is the preferred method to determine urinary PAC metabolites. Although sensitive and specific, GC/HRMS is time consuming and costly. The ELISA method had a range from 14-720 ng/ml 1-hydroxypyrene equivalents with a lower limit of detection (LOD) of 14 ng/ml urine. ELISA and GC/HRMS PAC metabolite measurements had a statistically significant correlation and the PAC ELISA results were indicative of potential asphalt exposure. PAC ELISA is promising as a more rapid and less costly routine method for determining worker exposure to PACs in asphalt emissions. |
Use of direct reading surface sampling methods for site characterization and remediation of methamphetamine contaminated properties
Snawder JE , Striley CAF , Esswein EJ , Hessel J , Sammons DL , Robertson SA , Johnson BC , MacKenzie BA , Smith JP , Walker CV . J ASTM Int 2011 8 (6) JAI103481 Residual methamphetamine contamination in clandestine laboratories represents a hazard to emergency response personnel, remediation workers and the general public. To address this threat, two rapid, sensitive surface sampling techniques to assess the location and level of methamphetamine contamination were developed. Both methods employ established industrial hygiene surface sampling materials (wipes and swabs) but differ in their sensitivity and detection technology. One method, based on colorimetric disclosure, detects and confirms a collected sample or visible residues. The second method uses a lateral flow immunochemical assay (LFIA) for semi-quantitative detection of trace contamination. The National Institute for Occupational Safety and Health (NIOSH) partnered with public health agencies to develop applications of the methods for assessment of methamphetamine contamination of suspected properties. These applications focused on safe strategies for site assessment, hazard characterization, and remediation effectiveness. To conduct the field studies, NIOSH researchers and their partners visited more than a dozen suspected laboratories including mobile labs, abandoned properties, occupied residences, and motel rooms. NIOSH found greater than 95% agreement between positive identification of the presence of methamphetamine by LFIA and laboratory-based, liquid chromatography mass spectroscopy (LC- MS) methods. Test results were used to develop site assessments and make personal protective equipment recommendations. Results were also used to conduct process-based decontamination of properties and to make health-based decisions on remediation, re-occupancy of residences, as well as determine the degree of contamination of personal property in an inactive clandestine laboratory. By partnering with stakeholders, NIOSH was able to achieve two primary goals: (1) to develop a level of awareness in health department sanitarians, law enforcement personnel and other first responders that methamphetamine surface contamination was a potentially significant route of exposure; (2) to validate our methods in the field and to develop protocols for proper use and interpretation of the results. |
An interlaboratory comparison of three multiplexed bead-based immunoassays for measuring serum antibodies to pneumococcal polysaccharides
Whaley MJ , Rose C , Martinez J , Laher G , Sammons DL , Smith JP , Snawder JE , Borrow R , Biagini RE , Plikaytis B , Carlone GM , Romero-Steiner S . Clin Vaccine Immunol 2010 17 (5) 862-9 Serotype-specific IgG, as quantified by a standardized WHO ELISA, is a serologic end-point used to evaluate pneumococcal polysaccharide-based vaccine immunogenicity. Antibodies to each vaccine polysaccharide in licensed multivalent vaccines are quantified separately; this is laborious and consumes serum. We compared three bead-based immunoassays, a commercial assay (xMAP(R)Pneumo14, Luminex) and two in-house assays (Health Protection Agency [HPA] and Centers for Disease Control and Prevention [CDC]) using WHO recommended standard reference and reference sera (n=11) from vaccinated adults. Multiple comparisons of the IgG concentrations for seven conjugate vaccine serotypes were performed by sample (percent error), serotype (equivalency testing), and laboratory (concordance correlation coefficient [CCC]). When comparing concentrations by sample, bead-based immunoassays generally yielded higher antibody concentrations than ELISA and had higher variability for serotypes 6B, 18C, and 23F. None of the three assays met the current WHO recommendation of 75% of sera falling within +/-40% of the assigned antibody concentrations for all seven serotypes. When compared by serotype, CDC and HPA were equivalent for 5 of 7 serotypes, whereas Luminex was equivalent for 4 of 7 serotypes. When overall mean IgG concentrations were compared by laboratories, a higher level of agreement, CCC close to 1, was found among bead-based immunoassays than between the assays and WHO assignments. When compared to WHO assignments, the HPA assay out performed (r = 0.920, rc = 0.894, Ca = 0.972) the other assays. Additional testing with sera from immunogenicity studies should demonstrate the applicability of this methodology for vaccine evaluation. |
Measurement of methamphetamine on surfaces using surface plasmon resonance
Smith JP , Martin A , Sammons DL , Striley C , Biagini R , Quinn J , Cope R , Snawder JE . Toxicol Mech Methods 2009 19 416-21 Field methods are needed to assess the contamination of surfaces by methamphetamine from illicit drug manufacturing. This study performed a feasibility study on the use of a surface plasmon resonance (SPR) based instrument (SensiQ Discovery) in the evaluation of surface contamination by methamphetamine. The main goal was to see if the method could be sensitive enough for field measurements. A competitive immunochemical assay was developed for the instrument which was able to measure methamphetamine at 9 ng/ml with a range of 9-250 ng/ml. Methamphetamine was spiked onto ceramic tiles and the assay was able to detect methamphetamine contamination at 25 ng/100 cm(2), which is below the 50 ng/100 cm(2) standard used for surface cleanup assessment. The instrument is compact and mobile and is sensitive enough for use for measurement of methamphetamine on surfaces, so it is a candidate for a field method for methamphetamine surface contamination. Its use for this application will require further development of the instrument to make it more convenient to use. Also further evaluation of ruggedness and use of the instrument under various environmental conditions such as temperature and humidity are needed to define conditions under which the instrument can be employed in field measurements. |
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