ABSTRACT Malaria and babesiosis are significant parasitic infections, requiring timely diagnosis to avoid severe complications. This study retrospectively compared hematology thin smears (HS) with parasitology thick and thin blood smears (PS), the gold standard for diagnosis, to evaluate HS’s performance in detecting Plasmodium and Babesia infections. Of 529 cases with paired HS and PS testing, HS demonstrated 93.3% sensitivity and 99.8% specificity, with 97.7% positive and 99.4% negative predictive values. When only considering new diagnoses, HS and PS were 100% concordant. No significant difference was found in percent parasitemia between HS and PS, highlighting HS as a reliable diagnostic tool in settings where PS or other diagnostic modalities may not be readily available. IMPORTANCE This study demonstrates that hematology thin smears—often available in laboratories that may not have other means of diagnosing blood parasite infections such as parasitology thick and thin smears, rapid diagnostics tests, or polymerase chain reaction—are an accurate and reliable way to diagnose Plasmodium and Babesia infections in a low prevalence setting.

Disseminated sporotrichosis is a severe opportunistic infection that often affects immunocompromised patients after a cutaneous inoculation. Here we present a rare case of disseminated sporotrichosis discovered as a solitary intramedullary thoracic spinal cord lesion in an immunocompetent patient. A 37-year-old man presented with progressive lower limb weakness and sensory changes over 1 week. A spinal magnetic resonance imaging (MRI) revealed a contrast-enhancing intramedullary lesion centered at T10. The patient was afebrile and reported no history of trauma or cutaneous lesions. The lesion was unresponsive to a trial of corticosteroids. A thoracic laminectomy was performed and a biopsy obtained. A cutaneous lesion on the arm was concurrently discovered, which was also biopsied. Both the skin and spinal cord biopsies showed Sporothrix schenckii by macroscopic and microscopic morphology which were later confirmed by MALDI-TOF mass spectrometry. This is a rare case of intramedullary disseminated sporotrichosis affecting the central nervous system of an immunocompetent patient. This unusual presentation should be taken into consideration when such intramedullary lesions are encountered.

A patient suffered a non-fatal wet drowning in a freshwater lake and developed bacteremia several days later. Blood culture grew a Gram-negative rod that could not be identified by MALDI-TOF MS. 16S ribosomal RNA sequencing of the isolate identified the microbe as Hydrogenophaga laconesensis––an environmental microbe commonly found in freshwater. The recovery of multiple pathogenic microorganisms (although not Hydrogenophaga laconesensis) from culture of respiratory specimens prompted the initiation of antibiotic therapy with cefepime and, later, vancomycin. The patient’s clinical course gradually improved over the course of two weeks and she was ultimately discharged home with minimal sequelae. To our knowledge, this is the first evidence of human infection with bacteria in the Hydrogenophaga genus. Hydrogenophaga may be considered in cases of freshwater near-drowning, and MALDI-TOF MS databases should be updated to include Hydrogenophaga laconesensis.

This study evaluated the performance and clinical utility of performing intravascular catheter tip cultures (CTC). A retrospective chart review was conducted over a 2.5 year period on all patients who demonstrated growth of at least one organism on CTC. There were a total of 391 CTC performed. 88 (23%) grew at least one organism, while 303 (77%) had no growth. Of the positive CTC, 81 (92%) had blood cultures (BC) collected within 14 days, whereas 7 (8%) did not. Of the positive CTC with BC, 67 (83%) were BC-positive, whereas 14 (17%) were negative. For cases with growth on both CTC and BC, the organisms identified were concordant for 46 (69%) cases and discordant for 21 (31%). Of the concordant cases, 43 (93%) were clinically considered to be bacterial bloodstream infections that were secondary to a catheter infection. For all of the positive CTC cases total, there was no change in the antibiotics or management, with the exceptions of 2 out of 88 (2%) cases. Catheters were removed and cultured for an average of 38.6 h (range: -98 to 288 h) after positive BC results were available. Most CTC are negative, and for the CTC that are positive, most are concordant with BC results. CTC results are generally only available several days after positive BC results are known. The CTC results did not alter the antibiotic therapy or management, with the exceptions of rare cases. As such, this study concludes that CTC do not contribute diagnostic or therapeutic value. Therefore, current guidelines by the Infectious Diseases Society of America on catheter-related bloodstream infection diagnosis should be revised to exclude CTC collection. IMPORTANCE In patients with intravascular catheters who are febrile or have positive blood cultures and no other obvious sources of infection, catheter tip cultures are often obtained to evaluate potential catheter-related bloodstream infections. However, previous studies reported that the management of catheter-related bloodstream infection cases is entirely based on blood culture growth and susceptibilities and that catheter tip cultures have low diagnostic positive predictive value. Our study represents the largest contemporary evaluation that includes chart reviews on all positive catheter tip culture cases. We found that positive cultures led to no changes in antibiotics or management, except for in two cases. Furthermore, 92% of positive catheter tip cultures were associated with blood culture collections, and catheter cultures were generally available only several days after the blood culture results were known. Thus, our study supports the claim that positive catheter tip cultures add limited diagnostic and therapeutic value in suspected catheter-related bloodstream infections.

We reviewed the electronic health records of 1,419 inpatients with anterior nares (AN) and oropharynx (OP) MRSA PCR tests. Concordance was 96.5%. In discordant cases, AN negative-OP positive results increased detection of probable MRSA pneumonia by only 0.3%. A dual testing approach has limited utility in detecting MRSA pneumonia and increases resource utilization.

Blood cultures (BC) for bacteria and yeast have traditionally been incubated for 5 days using modern instruments. Many organisms may grow sooner, and the need for the full 5-day incubation period has been questioned. This study evaluated the clinical significance of isolates recovered beyond 96 h. A retrospective chart review was conducted on all positive BC (+BC) performed via BD Bactec FX with >96 h of incubation from 5/2019 to 1/2022 at the UW Health University Hospital clinical microbiology laboratory. A total of 59,958 BC were performed; 6,031 (10%) were +BC. Of +BC, 104 (2%) demonstrated growth >96 h. The 104 cultures were from 89 patients and included 12 (12%) Staphylococcus aureus (1 MRSA), 9 (9%) yeast (8 Candida sp.), 8 (8%) Escherichia coli and 7 (7%) Enterococcus sp. (1 VRE) isolates. Fifty-six percent (n = 50) of the 89 +BC >96 h cases were clinically significant, and 26% (n = 13) resulted in antibiotic adjustments based on the +BC; 4 of these had previous positive cultures. Of the remaining 37 clinically significant +BC >96 h for which no antibiotic changes were made, 32 patients had previous positive cultures. The majority (98%) of BC bottles were positive before 96 h. For isolates that required >96 h, most (56%) were considered clinically significant, including S. aureus and E. coli cultures. Changes to antibiotic therapy were made in a minority (26%) of clinically significant cases. Based on these findings, under routine conditions, laboratories using BD Bactec FX should maintain a 120 h incubation period.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) asymptomatic infections may play a critical role in disease transmission. We aim to determine the prevalence of asymptomatic SARS-CoV-2 infection at 2 hospital systems in 2 counties in Wisconsin. The SARS-CoV-2 prevalence was 1% or lower at both systems despite the higher incidence of coronavirus disease 2019 (COVID-19) in Milwaukee County.

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Pneumocystis jirovecii can cause severe pneumonia in immunocompromised patients, which can be life threatening if left untreated. Despite the widespread use of polymerase chain reaction (PCR) within the clinical laboratory setting, FDA-approved PCR assays are not readily available for the detection of Pneumocystis from respiratory samples. Using the Luminex ARIES system-an open-channel, automated, sample-to-answer PCR platform-the cell division cycle 2 (cdc-2) gene can be targeted for the detection of Pneumocystis. This novel TaqMan-based, real-time PCR assay offers improved sensitivity compared to staining or immunofluorescence while reducing turnaround time and eliminating the challenges surrounding microscopic identification. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Primer/probe master mix preparation Basic Protocol 2: Positive control (cdc-2) plasmid preparation Basic Protocol 3: Mucus digestion Basic Protocol 4: Cell lysis Basic Protocol 5: Carrier RNA/proteinase K preparation Basic Protocol 6: Cassette assembly Basic Protocol 7: Running the assay Basic Protocol 8: Interpreting results.

Abstract Background This study evaluated the yield of testing NP vs BAL specimens using a multiplex PCR respiratory viral panel (RVP). Methods A retrospective chart review was conducted on all patients from 10/2017-3/2021 who had both an NP swab and BAL tested by RVP within a 4-week period. Results There were 477 cases where patients had both an NP and BAL specimen tested by RVP. Results were NP-/BAL- for 361 (76%) cases, NP+/BAL+ for 58 (12%), NP-/BAL+ for 40 (8%), and NP+/BAL- for 18 (4%). For NP+/BAL+, NP-/BAL+, and NP+/BAL-, respectively, rhinovirus was detected in 23 (40%), 3 (8%), and 16 (89%) cases (p< 0.001); influenza A or B in 9 (16%), 7 (18%), and 0 (0%) (ns); adenovirus in 3 (5%), 10 (25%), and 2 (11%) (p< 0.05); metapneumovirus in 9 (16%), 8 (20%), 2 (11%) (ns); RSV in 8 (14%), 6 (15%), and 1 (6%) (ns); and, parainfluenza in 7 (12%), 6 (15%), and 1 (6%) (ns), respectively. Average ages were 48, 48, and 48 years; numbers of males were 34 (58%), 28 (70%), and 11 (61%); immunocompromised were 56 (97%), 37 (92%), and 17 (94%); and, 16 (28%), 10 (25%), and 6 (33%) had an active malignancy, respectively (all ns). Average symptom durations prior to presentation were 7.0, 13.1, and 9.6 days (ns); pulmonary exams were abnormal in 35 (60%), 24 (60%), and 5 (28%) cases (p< 0.05); shortness of breath (SOB) was present in 40 (69%), 25 (62%), and 8 (44%) (ns); lower respiratory tract infection (LRTI) symptoms were absent in 1 (2%), 12 (30%), and 8 (45%) cases (p< 0.01); when spirometry values were available, they were reduced in 28/31 (90%), 15/19 (79%), and 3/8 (37%) cases (p< 0.05); and, mean SpO2 levels were 91.5%, 93.9%, and 93.7% (ns), respectively. Mean temperatures were 99.0F, 99.0F, and 99.1F (ns); chills, sweats, and malaise were present in 27 (47%), 13 (33%), and 3 (17%) cases (p< 0.05); GI symptoms were present in 20 (34%), 5 (13%), and 10 (56%) cases (p< 0.05); and, acute kidney injury was present in 38 (66%), 13 (33%), and 6 (33%) cases (p< 0.05), respectively. Conclusion Most (88%) RVP test results were concordant between NP and BAL. There were significant differences between cases of NP+/BAL+, NP-/BAL+, and NP+/BAL-. Rhinovirus and GI symptoms were more common for NP+/BAL- vs NP-/BAL+. Conversely, pulmonary exams were more often abnormal and spirometry values reduced for NP-/BAL+ vs NP+/BAL-. Disclosures All Authors: No reported disclosures

Background Methicillin-susceptible/methicillin-resistant Staphylococcus aureus (MSSA/MRSA) can be directly identified from positive blood culture bottles using molecular methods, but discrepancies with phenotypic testing occasionally occur. We sought to determine the incidence and clinical impact of these discrepancies. Methods Positive blood culture bottles are routinely tested in the hospital laboratory for mecA via the Xpert MRSA/SA blood culture assay which uses real-time polymerase chain reaction (PCR), and antimicrobial susceptibility testing (AST) via MicroScan PC33 is performed on recovered S. aureus isolates; discrepancies between the Xpert MRSA/SA blood culture assay and AST are resolved by repeat and supplemental testing. A retrospective review of medical and laboratory data from January 2015 to June 2018 was performed on all patients that had discordant Xpert MRSA/SA blood culture assay and AST results. Results Approximately 1410 PCR assays were performed, and there were 6 (0.4%) cases with discordant AST results. Five cases were classified as MSSA by PCR but MRSA by AST, and 1 case was classified as MRSA by PCR but MSSA by AST. For the former group, antimicrobial therapy was changed in 3 patients to cover MRSA, whereas the remaining 2 patients were already being treated for MRSA; for the latter case, the patient was treated for MRSA during the initial hospitalization but was later readmitted with disseminated MSSA. Discrepancies were likely due to presence of an staphylococcal cassette chromosome mec variant (n = 2), borderline oxacillin resistance (n = 1), heterogeneous MRSA (n = 1), or undetermined (n = 2). Conclusions Rapid identification of MRSA bacteremia via PCR provides actionable information to direct empiric treatment. The PCR results are highly accurate, though are infrequently not corroborated by AST due to various reasons.

BACKGROUND:Multiple factors have led to an extremely high volume of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcription polymerase chain reaction (RT-PCR) testing. Concerns exist about sensitivity and false-negative SARS-CoV-2 RT-PCR testing results. We describe a retrospective observational study examining the utility of repeat nasopharyngeal (NP) SARS-CoV-2 RT-PCR testing at an academic center in a low-prevalence setting.METHODS:All patients within our health system with >1 NP SARS-CoV-2 RT-PCR test result were included. SARS-CoV-2 RT-PCR testing was performed according to 1 of 4 validated assays. Key clinical and demographic data were collected, including whether the patient was inpatient or outpatient at time of the test and whether the test was performed as part of a person under investigation (PUI) for possible coronavirus disease 2019 or for asymptomatic screening.RESULTS:A total of 660 patients had >1 NP SARS-CoV-2 PCR test performed. The initial test was negative in 638. There were only 6 negative-to-positive conversions (0.9%). All 6 were outpatients undergoing a PUI workup 5-17 days after an initial negative result. In >260 inpatients with repeat testing, we found no instances of negative-to-positive conversion including those undergoing PUI or asymptomatic evaluation.CONCLUSIONS:In a low-prevalence area, repeat inpatient testing after an initial negative result, using a highly analytically sensitive SARS-CoV-2 RT-PCR, failed to demonstrate negative-to-positive conversion. The clinical sensitivity of NP RT-PCR testing may be higher than previously believed. These results have helped shape diagnostic stewardship guidelines, in particular guidance to decrease repeated testing in the inpatient setting to optimize test utilization and preserve resources.

Background: Group B Streptococcal (GBS) infections in the United States are a leading cause of meningitis and sepsis in newborns. The CDC, therefore recommends GBS screening for all pregnant women at 35–37 weeks of gestation and administration of intrapartum prophylaxis (in those that tested positive) as an effective means of controlling disease transmission. Several FDA approved molecular diagnostic tests are available for rapid and accurate detection of GBS in antepartum women. Method: In this study, we report a clinical comparison of the Xpert GBS LB assay and a novel FDA-cleared test, Revogene GBS LB assay. A total of 250 vaginal-rectal swabs from women undergoing prenatal screening were submitted to the University of Wisconsin’s clinical microbiology laboratory for GBS testing. Results: We found 96.8% of samples were concordant between the two tests, while 3.2% were discordant with a positive percent agreement of 98.0% and a negative percent agreement of 96.5% between the Revogene GBS LB assay and the GeneXpert GBS LB assay. Conclusion: Overall, we report that both assays perform well for the detection of GBS colonization in pregnant women.

Abstract Background Nucleic acid amplification testing (NAAT) for influenza A virus (IAV), influenza B virus (IBV), and respiratory syncytial virus (RSV) is a standard component of diagnosis of infections with these pathogens. At our institution, current standard of practice is to collect nasopharyngeal (NP) samples for such NAAT. In an effort to provide clinicians and patients a simpler, more comfortable sample collection option, we evaluated the use of nasal samples for NAAT, compared to NP samples. Methods Both nasal and NP specimens were collected from each of 58 patients seen in our emergency department (January – March 2020). NP samples were collected using minitip FLOQswabs; nasal samples were collected using regular or minitip FLOQswabs. Nasal and NP samples were processed using the same protocol and tested for influenza viruses and RSV using the Cepheid GeneXpert (Xpress Flu/RSV) platform. Results In total, 20 NP samples tested negative for virus and 38 tested positive (16 IAV-positive, 14 IBV-positive, 8 RSV-positive). There were 3 cases (5% of total cases) in which qualitative (positive/negative) results from the corresponding nasal samples were not in agreement with results derived from NP samples. These were considered false-negative results; one such discrepancy was resolved upon re-testing the same samples. Overall positive percent agreement between nasal- and NP-derived results was 92% (35/38), and negative percent agreement was 100% (20/20). Among samples testing positive for virus by both NP and nasal sampling methods, we found that the average cycle threshold (Ct) value for IAV detection was 5.1 cycles (n = 16, SEM = 0.83) higher for nasal samples than for NP samples. The average Ct for IBV detection was 3.3 cycles (n = 12, SEM = 1.87) higher for nasal than for NP samples. The average Ct for RSV detection was 1.9 cycles (n = 7, SEM = 1.57) higher for nasal than for NP samples. Conclusion These results suggest that recovery of viral RNA from nasal samples is lower than that from nasopharyngeal samples, particularly for influenza viruses. This decreased detection of viral RNA from nasal samples may explain the false-negative results seen in our discrepant cases. These data suggest that a decrease in recovery of viral RNA by nasal sampling may translate to decreased diagnostic accuracy. Disclosures All Authors: No reported disclosures

INTRODUCTION:Early reports have raised concerns regarding the clinical sensitivity of nasopharyngeal SARS-CoV-2 reverse transcriptase-polymerase chain reaction (RT-PCR) testing for patients with COVID-19 symptoms, which has led to requests for repeat testing at our institution. However, to our knowledge, there are no reports to date of the utilization or results of repeat testing to help guide this practice.METHODS:The authors searched the institutional laboratory information system for consecutive patients who were tested for SARS-CoV-2 by RT-PCR of a nasopharyngeal specimen over a 1-month period. Characteristics and results of patients who received a single or multiple tests were documented and analyzed.RESULTS:Six thousand three (6003) tests were performed on 5757 patients; 272 (4.7%) patients were positive based on their initial test results. Two hundred thirty-six (4%) patients were tested more than once, with 226 (96%) tested twice. The largest proportion of these patients (n=160, 71%) were those who had an initial negative test followed by a repeat test for persistent symptoms. This group included all 7 patients who had discordant positive results on their second test; the result concordance rate within this group was 96%.CONCLUSION:In a population of patients with a low positive rate for SARS-CoV-2 by nasopharyngeal RT-PCR testing, repeat nasopharyngeal testing of negative patients who have persistent symptoms still yields a negative result in 96% of the cases.

Abstract Background The Abbott Laboratories SARS-CoV-2 IgG assay and the DiaSorin LIASON SARS-CoV-2 S1/S2 IgG assay are both chemiluminescent immunoassays that qualitatively detect IgG antibodies against SARS-CoV-2 antigens. The Abbott assay detects IgG against the viral nucleocapsid (N) protein, while the DiaSorin assay uses antigen derived from the viral spike (S) protein. Here we evaluate the performance of these two assays at our institution. Methods 45 patient samples (serum or plasma) were tested for anti-SARS-CoV-2 IgG by both the Abbott and DiaSorin assays. The samples were previously characterized at a national reference laboratory using the Abbott assay or by an in-house PCR-based test for SARS-CoV-2 RNA. Samples yielding discordant results across platforms were further tested using the EUROIMMUN Anti-SARS-CoV-2 ELISA (IgG) assay at the reference laboratory. Results 22 samples tested negative for SARS-CoV-2 by the reference lab Abbott assay, and 23 tested positive by the same reference lab test (n = 13) or by an in-house PCR-based test (n = 10). The 22 samples characterized as negative again tested negative by both the Abbott (in-house) and DiaSorin assays (100% NPA). Among the 23 samples characterized as positive, all 23 tested positive by the Abbott assay (100% PPA), while only 15 tested positive by the DiaSorin assay (65% PPA). For each of the 8 discordant cases, samples were further tested by EUROIMMUN assay, which targets the S protein; 7 of the 8 samples tested negative by this assay, in agreement with the DiaSorin test results. Thus, for the discordant cases, testing for IgG against N (in-house and reference lab Abbott assays) gave positive results, while testing for IgG against S (DiaSorin and EUROIMMUN assays) mostly gave negative results. Conclusion These findings highlight the importance of the differences between various SARS-CoV-2 antibody tests, and providers should be aware of the specific antigenic target(s) in each test. Selection of a specific assay may depend on the need to assess past exposure to SARS-CoV-2 (for which a nucleocapsid target may be more sensitive) or to detect neutralizing antibodies (for which a spike target may be more relevant). This also has implications for disease surveillance as reliance on anti-spike antibodies alone may underestimate infection prevalence. Disclosures All Authors: No reported disclosures

Abstract Background Plazomicin, a novel aminoglycoside, is active against carbapenem-resistant Enterobacteriaceae (EB) and is not inhibited by most aminoglycoside modifying enzymes that affect gentamicin and tobramycin. We investigated the activity of plazomicin against resistant EB clinical isolates and compared disk diffusion (DD) vs. gradient diffusion (GD) results. Methods EB isolates that were carbapenem resistant and/or resistant to both gentamicin and tobramycin were retrieved from the UW Health clinical isolate repository. Each isolate was tested against plazomicin using both DD (MAST Group Ltd. Plazomicin disk 30 µg) and GD (Liofilchem Plazomicin MIC Test Strip 0.16–256 µg/mL) methods according to manufacturer instructions and using FDA clinical breakpoints for interpretation. Results 51 isolates were tested: 21 E. coli, 9 P. mirabilis, 7 E. cloacae, 6 K. pneumoniae, 3 K. oxytoca, 3 S. marcescens, 1 K. aerogenes, and 1 C. freundii. Specimen sites included: 29 blood, 8 urine, 8 soft tissue or bone, 5 intra-abdominal, and 1 sputum. Previous phenotypic AST results demonstrated 19 (37%) were CRE, of which 5 were also gentamicin and tobramycin resistant, and 32 (63%) were tobramycin and gentamicin resistant but carbapenem susceptible. Plazomicin zone diameters and minimal inhibitory concentrations (MIC) for all isolates are shown in the figure (data jittered to show frequency). There was a significant correlation between increased MIC and smaller zone diameters (Pearson coefficient −0.443, P = 0.001). However, while all 51 isolates were susceptible by DD breakpoints, only 46 (92%) were susceptible by GD breakpoints. All 5 discordant results were P. mirabilis which had an MIC of 4 µg/mL (intermediate) but zone diameters of 20–21 mm (susceptible). Conclusion Concordance between plazomicin DD and GD susceptibility was only 92%. All 5 discordant results were P. mirabilis. Surveillance studies demonstrate >80% of P. mirabilis have MIC of 2–4 mg/L. Given the DD breakpoint is 16 mm, our data suggest DD was overly active in our sample set. Comparison of DD and GD to reference broth microdilution against a larger set of isolates is warranted to determine which method is optimal; however, our data suggest DD may result in categorical errors for P. mirabilis. Disclosures Alexander Lepak, MD, Paratek Pharmaceuticals: Research Grant; Tetraphase Pharmaceuticals: Research Grant.

Abstract Background Anterior nares (AN) MRSA PCR can help identify MRSA colonization as a risk factor for MRSA pneumonia and can be especially useful, given high NPV, in making treatment decisions when lower respiratory tract (LRT) cultures are lacking. Oropharynx (OP) MRSA carriage without AN colonization can occur suggesting the potential benefit of duel site screening, but doubles resource utilization. We evaluated concordance between the AN and OP sites and whether the addition of OP MRSA PCR testing provides clinical benefit. Methods MRSA PCR was performed using Xpert SA Nasal Complete (Cepheid; FDA-cleared and modified). Results were retrieved from January 2017 to July 2018 for adult in-patients who received both AN and OP testing within the same calendar day. Medical charts were reviewed for a clinical course, respiratory culture results, and effect of discordant PCR results. Results AN and OP MRSA PCRs were performed on 1,419 adult inpatients, concordance was 96.5% (n = 1370, see Table). In 38 of 49 discordant cases, PCR was used to evaluate the etiology of pneumonia. Of those, 22 (58%) had LRT culture results available within 48 h to direct therapy. We further evaluated the value of OP PCR by focusing on AN-/OP+ (n = 22) discordant results, of which 16 were used to evaluate pneumonia. LRT culture results were available in 7 (44%) of these cases. Three had isolation of MRSA; however, the remaining 4 were culture-negative but still received vancomycin for an average of 5 days. Of the 9 that were AN−, OP+, and without culture results, only 4 had clinical signs and symptoms consistent with MRSA pneumonia. OP MRSA PCR is $303. Conclusion OP and AN MRSA PCR screening are highly concordant in patients with pneumonia. 355 AN/OP PCRs (4/1419), at > $100,000 in additional healthcare costs, were needed to detect one potentially missed MRSA pneumonia compared with AN PCR only approach. Our results suggest addition of OP MRSA PCR: (1) has limited clinical utility for pneumonia evaluation as it is unlikely to be discordant with AN testing, which will not significantly alter the very high NPV and when discordant (AN-/OP+) has a <50% PPV, (2) is unlikely to be cost-effective, and (3) has unintended consequences such as overuse of MRSA therapy. Additionally, there is an opportunity to improve PCR ordering to include only those situations in which LRT cultures are lacking. Disclosures Alexander Lepak, MD, Paratek Pharmaceuticals: Research Grant; Tetraphase Pharmaceuticals: Research Grant.

Ureaplasma species primarily colonize in the human genitourinary tract and are a cause of nongonococcal urethritis. Rare cases of septic arthritis caused by these organisms have been reported in immunocompromised hosts; however, their pathogenic activity in hosts with competent immune status remains unclear. Here, we report a case of septic arthritis caused by Ureaplasma parvum in an adult immunocompetent male patient diagnosed by 16S rRNA gene sequencing.