444. Better Efficiency, Same Accuracy: Point-of-Care PCR for the Detection of Group A streptococcus in Noninvasive Skin Infections

Abstract

BackgroundGroup A streptococcus (GAS) is a common cause of skin and soft-tissue infections (SSTIs). Current diagnostic techniques are culture-based and time intensive, requiring the prescription of empiric antibiotics before results are available. New detection tools are needed to hasten the diagnosis and appropriate treatment of SSTIs. The Cobas® Liat® System is a point of care (POC), real-time PCR system developed by Roche Molecular Diagnostics and is used in the United States and Europe to detect GAS from throat swabs within 15 minutes. We evaluated the feasibility and performance characteristics of POC for the detection of GAS in non-severe SSTIs.MethodsWound swabs collected from patients presenting to the Whiteriver Indian Health Service Hospital with non-severe SSTIs requiring only outpatient treatment were eligible for inclusion. Two swabs were collected: one swab was cultured on sheep’s blood agar, and the other swab was tested using POC. Compared with culture, we determined the sensitivity (SN), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) for POC to detect GAS in wound samples. We performed chart reviews 30-days from eligibility to assess the potential impact of POC systems on antibiotic use and healthcare utilization for SSTIs.ResultsTo date, we have tested 100 (25%) of our target 400 samples (enrollment will be complete in August 2019). Of the 100 samples, 50 (50%) tested positive for GAS by POC, all of which were culture positive for GAS, 49 tested negative by POC (2 after a first invalid result), all of which tested culture negative for GAS (table), and 1 had an invalid POC result even after repeat testing (culture positive for MRSA only) and was excluded from further analysis. Among samples with a valid POC result, POC SN was 100%, SP was 100%, PPV was 100%, and NPV was 100%. The most common mono-infections were MRSA (22%), GAS (18%), and CoNS (6%). Among GAS cases, MSSA (32%) and MRSA (18%) co-infection was common.ConclusionPOC PCR is highly sensitive and specific for the detection of GAS in non-severe SSTIs. To our knowledge, this is the first prospective study to use this technology for wound samples. POC PCR methods have the potential to accelerate identification of SSTI pathogens and improve antibiotic prescribing. Disclosures All authors: No reported disclosures.

Sudden Cardiac Arrest in an American Indian Infant

“…18 Among 400 skin infections treated as an outpatient, > 50% were culture positive for GAS. 19 Although speculative, our patient may have been suffering from macrolideresistant GAS pharyngitis 5 weeks before his death when he presented with a febrile illness diagnosed as acute otitis media and was treated with azithromycin. No rapid test or culture for GAS was obtained.…”