Use of saliva-based qPCR diagnostics for the accurate, rapid, and inexpensive detection of strep throat.

OBJECTIVES: Outpatient health care facilities are essential for quickly diagnosing common infectious diseases such as bacterial and viral pharyngitis. The only form of pharyngitis requiring antibiotics is strep throat (ST); however, antibiotic prescription rates are much higher than ST prevalence, suggesting antibiotics are being inappropriately prescribed. Current rapid ST diagnostics may be contributing to this problem due to the low sensitivity and variable specificity of these tests. It is best practice to verify a negative ST diagnosis with a group A Streptococcus (GAS) culture, but many clinics do not perform this test due to the additional cost and 24-72 h required to obtain results. This indicates there is great need for more accurate rapid diagnostic tools in outpatient facilities. We hypothesized that next generation qPCR technology could be adapted to detect GAS DNA from saliva samples (instead of the traditional throat swab) by creating a simple, fast, and inexpensive protocol. METHODS: Saliva specimens collected from patients at James Madison University Health Center were used to test the effectiveness of our Chelex 100-based rapid DNA extraction method, followed by a fast protocol developed for the Open qPCR machine to accurately detect ST. RESULTS: Our final saliva processing and qPCR protocol required no specialized training to perform and was able to detect ST with 100 % sensitivity and 100 % specificity (n=102) in 22-26 min, costing only $1.12 per sample. CONCLUSIONS: Saliva can be rapidly analyzed via qPCR for the accurate and inexpensive detection of ST.

Global patterns of necrotizing soft tissue infections: A systematic review and meta-analysis.

BACKGROUND: Frequency, microbiology, and outcomes of necrotizing soft tissue infections vary based on locoregional and environmental factors; however, there has been no global survey of these patterns. We performed a systematic review/meta-analysis on published reports of necrotizing soft tissue infections from across the globe. METHODS: Peer-reviewed empirical studies examining rates of polymicrobial and monomicrobial necrotizing soft tissue infections with microbial isolation and overall mortality rate were extracted along with geographic location using PubMed, Scopus, ProQuest, and Web of Science. Random-effects meta-analyses and sensitivity analyses were performed, adjusting for publication bias. Meta-regression analyses examined moderator effects of risk factors. RESULTS: One hundred and five studies (8,718 total patients) were included. Pooled prevalence of polymicrobial and monomicrobial infections were 53% and 37.9%, respectively. Truncal necrotizing soft tissue infections were commonly polymicrobial (P < .001), whereas monomicrobial infections prevailed in extremities (P = .008). Global prevalence of monomicrobial necrotizing soft tissue infections was observed to increase by 1.1% annually (P = .003). Staphylococcus aureus was the most common organism globally and in North America, Asia, the Middle East, and Africa, followed by Streptococcus pyogenes and Escherichia coli. Methicillin-resistant S. aureus accounted for 16% of necrotizing soft tissue infections globally. Overall mortality was 23.1%, observed to decline globally over the last decade (P = .020). No regional differences were noted for mortality. CONCLUSION: Although polymicrobial infections remain predominant worldwide, the incidence of monomicrobial infections is increasing. The observed decline in necrotizing soft tissue infection-related mortality is encouraging and may reflect advances in management, despite major variations in available healthcare resources globally.

ENT involvement and orobuccal movements' disorders in Pandas patients: assessment and rehabilitations tools.

OBJECTIVE: PANDAS are known as the spectrum of autoimmune pathologies related to a previous or current infection by group A beta-hemolytic streptococcus (SBEGA), dealing with several neuropsychiatric manifestations that mainly affect pediatric age. The main features consist of behavioral disease or movement disease characterized by acute-onset, presenting especially through infant period or adolescence. Specific manifestations, occurring during the progression of the disease, are the presence of otorhinolaryngologic symptoms (ENT) and orofacial movement disorders associated with temporomandibular joint pain. PATIENTS AND METHODS: We enrolled 130 children (5-15 years) with a clinical diagnosis of PANDAS between 2012 and 2018. Participants were assessed using ENT specific parameters, PSG to examine respiratory disorders and conventional audiological evaluation. Descriptive and comparative statistical analyses were performed with a control group of 51 healthy patients. RESULTS: The prevalence of ENT symptoms associated was significantly detected in 88 patients of 130 in Group A (relative frequency (%) 67.6; p=0.041) and in 51 patients of 130 in the control Group B (relative frequency (%) 39.2; p=0.063). In relation to prevalence of SDB, 54 subjects have presented nocturnal respiratory obstructive symptoms from mild to severe (relative frequency (%) 61.3; p=0.033) vs. 20 patients of Group B (relative frequency (%) 39.2; p=0.055). The obstructive severity average type was correlated to the consensual adenotonsillar development (size 3-4), (relative frequency (%) 45.4; p=0.047). The audiological deficits found were mostly of transmissive type with OME correlated and linked to the presence of occasional episodes of AOM. The four PANDAS patients who presented orobuccal dystonia (relative frequency (%) 4.54; p=0.091) achieved an improvement of the algic symptoms through the exercises of self-rehabilitation. CONCLUSIONS: Findings from our study show that respiratory diseases, characterizing a group of patients with pandas, are the direct consequences of the malformed or hypertrophic condition and suggesting in these conditions surgical therapy as an approaching tool.

Assessment of Test Performance and Potential for Environmental Contamination Associated with a Point-of-Care Molecular Assay for Group A Streptococcus in an End User Setting.

Although U.S. Food and Drug Administration-approved and CLIA-waived point-of-care (POC) molecular systems are being implemented in routine clinical practice, instrument reliability, test performance in the hands of end users, and the potential for environmental contamination resulting from use of POC molecular systems have not been extensively evaluated. We performed a prospective evaluation of the Roche cobas Liat group A streptococcus (GAS) assay compared to routine real-time PCR. We evaluated test accuracy, instrument failure rate, and monitored for environmental contamination when testing was performed by minimally trained end users in an Express Care Clinic environment. The overall concordance of the Liat GAS assay with routine testing was 97.2% (455/468). The average Liat failure rate across three analyzers was 6.6% (33/501) (range, 3.7 to 11.6%), and no environmental contamination was detected during the course of the study. The cobas Liat platform and GAS assay demonstrated reliable performance in the end user setting and may serve as a rapid, POC option for routine diagnostic testing for certain infectious diseases, including GAS.

Evaluation of Simplexa Group A Strep Direct Kit Compared to Hologic Group A Streptococcal Direct Assay for Detection of Group A Streptococcus in Throat Swabs.

Diagnosis of bacterial pharyngitis is confirmed by detection of group A Streptococcus (GAS) in patient throat samples. Testing of throat samples has historically relied on culture, but new molecular methods allow much faster test turnaround time (i.e., same day versus 48 to 72 h for culture). Our laboratory uses the Hologic GAS Direct (GASD) assay for screening more than 125,000 throat samples per year. Simplexa GAS Direct is a new real-time quantitative PCR (qPCR) assay that does not require initial DNA extraction. Performance of Simplexa qPCR was compared to GASD. A total of 289 throat swabs were collected from patients attending ambulatory clinics in Calgary, Alberta, Canada. A total of 60 (20.8%) of the samples were initially GAS positive by either method: 54 by both methods, 4 by Simplex qPCR alone, and 2 by GASD alone. An in-house PCR using a unique GAS primer set was used to resolve the 6 discrepant results. Overall, GASD compared to Simplexa qPCR had a sensitivity, specificity, positive predictive value, and negative predictive value of 93.1% versus 100%, 100% versus 100%, 100% versus 100%, and 98.31% versus 100%, respectively. Implementation of Simplexa qPCR in our laboratory setting would cost more but allow the high sample volume to be reported in half the time and save 0.62 medical laboratory technician (MLT) full-time equivalent (FTE). In comparison to culture, the implementation of Simplexa qPCR would save 2.79 medical laboratory assistant (MLA) FTE plus 0.94 MLT FTE. Simplexa qPCR has improved performance and diagnostic efficiency in a high-volume laboratory compared to GASD for GAS detection in throat swabs.

Klassisk barnsängsfeber existerar fortfarande - 9 fall bland anmälningar till LÖF under 2010­2014.

Puerpural fever still exist. A rare condition that must be kept in mind All 33 claims to the Swedish National Patient Insurance (LÖF) in 2010-2014 related to obstetric infections, of which 14 were due to endometritis, were examined. Nine women suffered from fulminant infections consistent with classical puerperal fever (childbed fever), 2 of which were life-threatening. They occurred unexpectedly, mainly after uncomplicated deliveries, and were usually caused by Group A streptococci. Five women suffered from endometritis with a mild or moderate clinical course. All occurred after early birth-related complications and were caused by low-virulent bacteria. In order for an infection to occur in a healthy woman who undergoes normal delivery, more virulent bacteria appear to be required. Since these bacteria may exist in the hospital environment, improved hygiene routines are a prerequisite for reducing the number of nosocomial infections.

Assessment of Cpa, Scl1 and Scl2 in clinical group A streptococcus isolates and patients from north India: an evaluation of the host pathogen interaction.

Group A streptococcus (GAS) infection remains a major concern due to multiple diseases including pharyngitis, impetigo, acute rheumatic fever (ARF) and rheumatic heart disease (RHD). It uses different adhesins and virulence factors like Cpa (collagen binding protein) and Scl (collagen-like protein) in its pathogenicity. Scl having similarities with human collagen may contribute to inducing autoimmunity in the host. Here we assessed gene expression, antibody titer of Cpa, Scl1 and Scl2 in both clinical GAS isolates (n = 45) and blood (n = 45) obtained from pharyngitis, ARF (acute rheumatic fever) and RHD respectively. Skin isolates (n = 30) were obtained from impetigo patients. The study revealed a total of 27 GAS emm types. Frequency of cpa, scl1, scl2 was high in ARF isolates. The antibody titer of these proteins was high in all isolates, and also in patients with pharyngitis and ARF. All isolates showed high binding affinity toward collagen I and IV, which further indicates a potential host pathogen interaction. Our study reflects a strong association of Cpa and Scls in early and post-GAS pathogenicity. However, the increased antibody titer of Scl1 and Scl2 during ARF may be attributed to a cogent immune response in the host.

Importance of whole genome sequencing for the assessment of outbreaks in diagnostic laboratories: analysis of a case series of invasive Streptococcus pyogenes infections.

Outbreaks of Streptococcus pyogenes hypervirulent clones are constant public health threats. In western Switzerland, an increase of severe cases of S. pyogenes invasive infections was observed between December 2015 and March 2016. Our aim was (i) to investigate these cases by the use of Whole Genome Sequencing (WGS) and (ii) to determine the specific virulome and resistome of each isolate in order to undertake adequate public health measures. Eleven Streptococcus pyogenes strains isolated from 11 patients with severe invasive infections between December 13, 2015 and March 12, 2016 were included in our study. Practically, emm-typing, MLST and WGS were used to investigate the relatedness between the isolates. The presence of virulence and antibiotic resistance genes as well as mutations in transcriptional regulators of virulence and in genes encoding for antibiotic targets were assessed. Three and two groups of isolates shared the same emm-type and ST type, respectively. Single Nucleotide Polymorphism (SNP) analysis revealed 14 to 32 SNPs between the strains of the same emm-type group, ruling out the possibility of a clonal outbreak. Mutations found in covS and rocA could partially explain an increased virulence. As these reassuring results were obtained in less than 10 days, no specific hospital hygiene and no dedicated public health measures had to be undertaken. WGS is a powerful technique to discriminate between closely related strains, excluding an outbreak in less than 10 days. Moreover, WGS provided extensive data on the virulome and resistome of all these strains.

Highly sensitive label-free dual sensor array for rapid detection of wound bacteria.

Wound infections are a critical healthcare concern worldwide. Rapid and effective antibiotic treatments that can mitigate infection severity and prevent the spread of antibiotic resistance are contingent upon timely infection detection. In this work, dual electrochemical pH and cell-attachment sensor arrays were developed for the real-time spatial and temporal monitoring of potential wound infections. Biocompatible polymeric device coatings were integrated to stabilize the sensors and promote bacteria attachment while preventing non-specific cell and protein fouling. High sensitivity (bacteria concentration of 102 colony forming units (CFU)/mL and -88.1±6.3mV/pH over a pH range of 1-13) and stability over 14 days were achieved without the addition of biological recognition elements. The dual sensor array was demonstrated to successfully monitor the growth of both gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) over time through lag and log growth phases and following antibiotic administration and in simulated shallow wounds conditions. The versatile fabrication methods utilized in sensor development, superior sensitivity, prolonged stability, and lack of non-specific sensor fouling may enable long-term in situ sensor array operation in low resource settings.

Development of a fast and low-cost qPCR assay for diagnosis of acute gas pharyngitis.

BACKGROUND: Group A streptococci (GAS) are the most common bacterial cause of acute pharyngitis and account for 15-30 % of cases of acute pharyngitis in children and 5-10 % of cases in adults. In this study, a real-time quantitative PCR (qPCR) based GAS detection assay in pharyngeal swab specimens was developed. METHODS: The qPCR assay was compared with the gold standard bacterial culture and a rapid antigen detection test (RADT) to evaluate its clinical performance in 687 patients. The analytical sensitivity of the assay was 240 cfu/swab. Forty-five different potential cross-reacting organisms did not react with the test. Four different laboratories for the reproducibility studies were in 100 % (60/60) agreement for the contrived GAS positive and negative swab samples. RESULTS: The relative sensitivities of the RADT and the qPCR test were 55.9 and 100 %; and the relative specificities were 100 and 96.3 %, respectively. Duration of the total assay for 24 samples including pre-analytical processing and analysis changed between 42 and 55 min depending on the type of qPCR instrument used. A simple DNA extraction method and a low qPCR volume made the developed assay an economical alternative for the GAS detection. CONCLUSION: We showed that the developed qPCR test is rapid, cheap, sensitive and specific and therefore can be used to replace both antigen detection and culture for diagnosis of acute GAS pharyngitis.

Assessment of Administrative Medical Claims Data for Public Health Surveillance of Invasive Group A Streptococcal Necrotizing Fasciitis in Tennessee.

OBJECTIVE: Necrotizing fasciitis (NF) is a severe manifestation of invasive group A streptococcal (iGAS) infection. NF is a rapidly progressive infection of the subcutaneous tissues, including the fascia, and accurate diagnosis and prompt treatment are critical. Population-based surveillance is conducted for iGAS, including the severe manifestations of NF, by the federally funded Active Bacterial Core surveillance (ABCs) program. METHODS: We used administrative claims data from a large managed care organization in Tennessee to enhance the public health surveillance for NF iGAS. For the period 2003-2012, we identified cases of NF in Tennessee by searching the claims database for diagnostic codes indicating the diagnosis of NF. We compared these cases with cases detected in selected Tennessee counties by ABCs. RESULTS: Of 356 managed care patients with a diagnostic code indicating NF, we determined that 20 (6%) patients had been hospitalized with iGAS infection and, therefore, were likely to be true NF cases. Of these 20 patients, only 11 matched with patients identified by ABCs; nine patients had not been previously identified by ABCs. During the same time period, 54 patients with NF were ascertained by ABCs. CONCLUSION: Administrative claims data have the potential to augment disease surveillance but require a large investment in resources compared with the few NF cases identified.

The Effect of Rapid Antigen Detection Test on Antibiotic Prescription Decision of Clinicians and Reducing Antibiotic Costs in Children with Acute Pharyngitis.

We aimed to investigate the effect of rapid antigen detection test (RADT) in the diagnosis of streptococcal pharyngitis, its impact on antibiotic prescription decision of pediatricians and influence on reduction of antibiotic treatment costs in children with pharyngitis. The study group consisted of 223 patients who were diagnosed with pharyngitis by pediatricians. The sensitivity and specificity of RADT were 92.1% (95% Cl: 78.6-98.3%) and 97.3% (95% Cl: 93.8-99.1%), respectively. In the first assessment, before performing RADT, pediatricians decided to prescribe antibiotics for 178 (79.8%) patients with pharyngitis. After learning RADT results, pediatricians finally decided to prescribe antibiotics for 83 (37.2%) patients with pharyngitis, and antibiotic prescription decreased by 42.6%. Antibiotic costs in non-Group A streptococcus pharyngitis, Group A streptococcus pharyngitis and all subjects groups decreased by 80.8%, 48%, and 76.4%, respectively. Performing RADT in children with pharyngitis has an important impact on treatment decision of clinicians, reduction of unnecessary antibiotic prescriptions and antibiotic costs.

Antibacterial resistance in Streptococcus pyogenes (GAS) from healthy carriers and tonsillitis patients and association with antibacterial sale in the Faroe Islands.

The aim of this study was to investigate the antibacterial resistance of Streptococcus pyogenes (GAS), and correlate the findings with the sales of erythromycin and tetracycline. General practitioners in the Faroe Islands were recruited to send oropharyngeal swabs. From an ongoing pneumococcal study, nasopharyngeal swabs were sampled from healthy children 0-7 years of age. Erythromycin susceptibility data from Iceland were obtained from the reference laboratory at the Landspitali University Hospital. Susceptibility testing in the Faroe Islands and Iceland was performed according to CLSI methods and criteria. The resistance rate to erythromycin and tetracycline found in patients in the Faroe Islands in 2009/2010 was 6% and 30% respectively. Tetracycline resistance in patients declined significantly from 2009 to 2010 (37-10%, p-value = 0.006 < 0.05) and differed significantly between age groups (p-value = 0.03 < 0.05). In Iceland, there was a peak in erythromycin resistance in 2008 (44%) and a substantial decrease in 2009 (5%). Although the prevalence of erythromycin and tetracycline resistance in the Faroe Islands and Iceland may be associated with antimicrobial use, sudden changes can occur with the introduction of new resistant clones.

Rapid antigen group A streptococcus test to diagnose pharyngitis: a systematic review and meta-analysis.

BACKGROUND: Pharyngitis management guidelines include estimates of the test characteristics of rapid antigen streptococcus tests (RAST) using a non-systematic approach. OBJECTIVE: To examine the sensitivity and specificity, and sources of variability, of RAST for diagnosing group A streptococcal (GAS) pharyngitis. DATA SOURCES: MEDLINE, Cochrane Reviews, Centre for Reviews and Dissemination, Scopus, SciELO, CINAHL, guidelines, 2000-2012. STUDY SELECTION: Culture as reference standard, all languages. DATA EXTRACTION AND SYNTHESIS: Study characteristics, quality. MAIN OUTCOME(S) AND MEASURE(S): Sensitivity, specificity. RESULTS: We included 59 studies encompassing 55,766 patients. Forty three studies (18,464 patients) fulfilled the higher quality definition (at least 50 patients, prospective data collection, and no significant biases) and 16 (35,634 patients) did not. For the higher quality immunochromatographic methods in children (10,325 patients), heterogeneity was high for sensitivity (inconsistency [I(2)] 88%) and specificity (I(2) 86%). For enzyme immunoassay in children (342 patients), the pooled sensitivity was 86% (95% CI, 79-92%) and the pooled specificity was 92% (95% CI, 88-95%). For the higher quality immunochromatographic methods in the adult population (1,216 patients), the pooled sensitivity was 91% (95% CI, 87 to 94%) and the pooled specificity was 93% (95% CI, 92 to 95%); however, heterogeneity was modest for sensitivity (I(2) 61%) and specificity (I(2) 72%). For enzyme immunoassay in the adult population (333 patients), the pooled sensitivity was 86% (95% CI, 81-91%) and the pooled specificity was 97% (95% CI, 96 to 99%); however, heterogeneity was high for sensitivity and specificity (both, I(2) 88%). CONCLUSIONS: RAST immunochromatographic methods appear to be very sensitive and highly specific to diagnose group A streptococcal pharyngitis among adults but not in children. We could not identify sources of variability among higher quality studies. The present systematic review provides the best evidence for the wide range of sensitivity included in current guidelines.

Cost-effectiveness analysis of rheumatic heart disease prevention strategies.

Rheumatic heart disease (RHD), secondary to group A streptococcal infection is endemic in the developing as well as parts of the developed world with significant costs to the patient, and to the healthcare system. We briefly review the prevalence and cost of RHD in developed and developing nations. We subsequently develop a Markov model to evaluate the cost-effectiveness of three strategies (vs standard no prevention) for preventing RHD in a developing world country: primary prophylaxis (throat swab to detect and subsequently treat group A streptococci as needed); primary prophylaxis (antibiotic prophylaxis for all) with benzathine penicillin G once monthly to all patients (ages 5-21 years) regardless of evidence of infection; and secondary prophylaxis with monthly only to those with echocardiographic evidence of early RHD. Our model suggests that echocardiographic screening and secondary prophylaxis is the best strategy although the strategies change depending on parameters used.

Burden of paediatric pyoderma and scabies in North West Queensland.

AIM: The study aims to assess the health burden of children admitted with 'scabies' to Mt Isa Hospital, the referral centre for North West Queensland, from 2006 to 2010. METHODS: This is a retrospective chart audit of admissions of children with 'scabies' including age, sex, date, residence, Indigenous status, result of skin swabs and length of stay, and the number of admissions with acute rheumatic fever (ARF) and acute post-streptococcal glomerulo-nephritis (APSGN) in that period. Financial burden was estimated from daily bed costs and transportation. RESULTS: There were 113 admissions with mean age of 23/12: 11% were <2/12 and mean stay was 4.5 days. 19 were admitted twice, 5 thrice and 2 four times. 7 individuals accounted for 25% of admissions. 'Scabies' accounted for 10.1% of medical admissions <5 years of age. Admissions increased from 10 in 2005 to 39 in 2010. The minimum cost per admission was $9584.07. Seventy-one per cent of swabs grew Group A streptococcus, all sensitive to penicillin. Sixty-three per cent of these were accompanied by Staphylococcus aureus, which was the sole organism in 18%. Sixty-four per cent of S. aureus were methicillin resistant. There were 29 admissions for ARF and 23 with APSGN. All children with 'scabies' and ARF and all but three with APSGN were Indigenous. CONCLUSION: Pyoderma and scabies are major health burdens in North West Queensland, requiring organised community-based prevention. The number of repeat admissions emphasises the futility of individual treatment.

Management of adults with acute streptococcal pharyngitis: minimal value for backup strep testing and overuse of antibiotics.

BACKGROUND: Rapid antigen detection tests (RADT) are commonly used to guide appropriate antibiotic treatment of group A beta-hemolytic streptococcal (GABHS) pharyngitis. In adults, there is controversy about the need for routine backup testing of negative RADT. OBJECTIVE: Estimate the costs and benefits in adults of routine backup testing by DNA Gen-probe of negative RADT (Acceava). DESIGN: Observational follow-up study. PARTICIPANTS: All patients aged 18 years and older visiting a Cleveland Clinic generalist physician in 2009 and 2010 with a visit diagnosis of acute pharyngitis (ICD codes 462, 034.0). MAIN MEASURES: The patients were identified using the Cleveland Clinic Epic Clarity database. We determined the proportion of false negative RADT, antibiotic prescription patterns and rate of serious suppurative complications within 30 days of the office visit. KEY RESULTS: Of 25,130 patients with acute pharyngitis, 19% had no testing and 81% were tested. Of the 15,555 patients that had a negative RADT and follow-up DNA probe, 6% had a positive DNA probe. Of the 953 patients who had a negative RADT and a positive DNA strep probe, 48% received an antibiotic prescription at the time of the visit and 51% received an antibiotic prescription after an average of 2.3 days. Only one patient with a negative RADT and no follow-up DNA probe developed a peritonsillar abscess. Overall, of the 15,555 DNA probes performed, management was altered in only 3% of the patients at a total cost of $1,757,715. Fifty-six percent received an antibiotic while only 19.5% had a confirmed strep throat diagnosis. CONCLUSIONS: The false negative rate of Acceava RADT for the diagnosis of GABHS pharyngitis was 6%. We question the benefit of routine DNA probe backup testing in adults because of its substantial cost, an average delay in antibiotic prescribing of over 2 days, and because suppurative complications are very uncommon. We found a high rate of inappropriate antibiotic prescribing.