Positive Nucleic Acid Amplification Test Research Articles

Spontaneous clearance of urogenital, anorectal and oropharyngeal Chlamydia trachomatis and Neisseria gonorrhoeae in women, MSM and heterosexual men visiting the STI clinic: a prospective cohort study

ObjectiveChlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections can clear without treatment. Despite high prevalence of anorectal infections in men who have sex with men (MSM) and women, studies on...

Antibody Testing in Estimating Past Exposure to Chlamydia trachomatis in the Netherlands Chlamydia Cohort Study.

The asymptomatic course of Chlamydia trachomatis (CT) infections can result in underestimated CT lifetime prevalence. Antibody testing might improve this estimate. We assessed CT antibody positivity and predictive factors thereof in the Netherlands Chlamydia Cohort Study. Women who had ≥1 CT Nucleic Acid Amplification Test (NAAT) in the study (2008–2011) and who provided self-reported information on NAATs were tested for CT major outer membrane protein specific IgG in serum (2016). CT antibody positivity was assessed and predictive factors were identified using multivariable logistic regressions, separately for CT-positive women (≥1 positive NAAT or ≥1 self-reported positive CT test) and CT-negative women (negative by study NAAT and self-report). Of the 3,613 women studied, 833 (23.1%) were CT -positive. Among the CT-negative women, 208 (7.5%, 95% CI 6.5–8.5) tested positive for CT antibodies. This increased CT lifetime prevalence with 5.8% (95% CI 5.0–6.5). Among women with a CT-positive history, 338 (40.6%, 95% CI 38.5–44.1) tested positive. Predictive factors for antibody positivity related to lower social economic status, sexual risk behavior, multiple infections, higher body mass index, and non-smoking. CT antibody testing significantly increased the lifetime prevalence. Combining NAAT outcomes, self-reported positive tests, and antibody testing reduced misclassification in CT prevalence estimates.

Community-wide Screening for Tuberculosis in a High-Prevalence Setting

BackgroundThe World Health Organization has set ambitious targets for the global elimination of tuberculosis. However, these targets will not be achieved at the current rate of progress.MethodsWe performed a cluster-randomized, controlled trial in Ca Mau Province, Vietnam, to evaluate the effectiveness of active community-wide screening, as compared with standard passive case detection alone, for reducing the prevalence of tuberculosis. Persons 15 years of age or older who resided in 60 intervention clusters (subcommunes) were screened for pulmonary tuberculosis, regardless of symptoms, annually for 3 years, beginning in 2014, by means of rapid nucleic acid amplification testing of spontaneously expectorated sputum samples. Active screening was not performed in the 60 control clusters in the first 3 years. The primary outcome, measured in the fourth year, was the prevalence of microbiologically confirmed pulmonary tuberculosis among persons 15 years of age or older. The secondary outcome was the prevalence of tuberculosis infection, as assessed by an interferon gamma release assay in the fourth year, among children born in 2012.ResultsIn the fourth-year prevalence survey, we tested 42,150 participants in the intervention group and 41,680 participants in the control group. A total of 53 participants in the intervention group (126 per 100,000 population) and 94 participants in the control group (226 per 100,000) had pulmonary tuberculosis, as confirmed by a positive nucleic acid amplification test for Mycobacterium tuberculosis (prevalence ratio, 0.56; 95% confidence interval [CI], 0.40 to 0.78; P<0.001). The prevalence of tuberculosis infection in children born in 2012 was 3.3% in the intervention group and 2.6% in the control group (prevalence ratio, 1.29; 95% CI, 0.70 to 2.36; P=0.42).ConclusionsThree years of community-wide screening in persons 15 years of age or older who resided in Ca Mau Province, Vietnam, resulted in a lower prevalence of pulmonary tuberculosis in the fourth year than standard passive case detection alone. (Funded by the Australian National Health and Medical Research Council; ACT3 Australian New Zealand Clinical Trials Registry number, ACTRN12614000372684.)

381 Diagnostic Accuracy of Point-of-Care Lung Ultrasound Among Patients Suspected of Having Pulmonary Tuberculosis

Pulmonary tuberculosis (PTB) is one of the leading causes of morbidity in the Philippines. Its prevalence is 438/100,000 population. The key to stopping the spread of the disease is accurate diagnosis and consistency of treatment. Diagnosis is based on clinical findings and confirmation of infection by chest x-ray, sputum analysis and molecular testing. This standard work-up is hampered by its cost, availability of diagnostic centers and the tediousness of testing especially in resource-limited areas. Recently, lung ultrasound (LUS) has become a valuable modality in diagnosing pulmonary diseases because of its portability, accuracy and cost-effectiveness. PTB is one of the few diseases that have not been extensively studied with regards to sonographic diagnosis. It is our intention to determine the diagnostic accuracy of LUS in patients with suspected PTB using chest radiography, sputum microscopy and nucleic acid amplification testing as the reference standard. If proven accurate, LUS can potentially simplify the detection of PTB in patients, facilitating quick diagnosis and dispensing of treatment. We conducted a cross-sectional, single-center, prospective observational study of 131 consecutive adult patients with presumptive PTB in a tertiary hospital outpatient clinic from September to November 2018. After securing consent, LUS was performed on all subjects to detect previously observed findings suggestive of PTB, namely: subpleural nodules, pleural effusion, consolidation and C-lines. A single emergency physician trained in LUS performed all the scans and a senior emergency medicine consultant with formal training in point-of-care ultrasound (POCUS) interpreted the clips. All patients subsequently underwent x-ray studies of the chest, direct sputum microscopy and nucleic acid amplification testing using a commercially available assay to confirm presence of tuberculosis infection. The sonographers were blinded to the results of the diagnostic work-up. Out of 131 patients, 102 patients had positive LUS findings of PTB. LUS compared to standard work-up had a specificity of 92.59% (75.71% to 99.09%), sensitivity of 55.77% (45.70% to 65.50%) and accuracy of 63.36% (54.50% to 71.60%) at 95% confidence interval (CI). Positive and Negative Likelihood ratios were 7.53 (1.96 to 28.88) and 0.48 (0.38 to 0.61), respectively. Furthermore, LUS had a positive predictive value of 96.67% and a negative predictive value of 25.21%. Our study demonstrated that LUS has robust specificity and can be an acceptable, simplified diagnostic test to detect PTB infection. This is compared to a reference standard consisting of positive chest x-ray findings, sputum microscopy and nucleic acid amplification testing. Follow-up studies comparing LUS to the current gold standard of TB diagnosis - the sputum culture, should be done in various stages of the disease to further validate the accuracy of LUS in PTB diagnosis.

Optimal Timing for Trichomonas vaginalis Test of Cure Using Nucleic Acid Amplification Testing.

The optimal timing for nucleic acid amplification testing (NAAT) posttreatment for Trichomonas vaginalis has not been fully established. Testing too soon posttreatment may detect remnant nucleic acid that is not from viable organisms, falsely misclassifying person as infected. The purpose of this study was to examine how long T. vaginalis nucleic acid is detectable postmetronidazole (MTZ) treatment. Women diagnosed with T. vaginalis treated with MTZ (2 g single-dose or 500 mg twice daily for 7 days multidose) self-collected a vaginal swab for NAAT at baseline and each week postcompletion of treatment through test of cure (TOC) at week 4, when a culture was also performed. Women who reported interim sexual exposure or who were culture positive at 4 weeks were excluded. Time to first negative NAAT was examined using Kaplan Meier analysis. All women receiving multidose metronidazole were NAAT-negative by 21 days and those receiving single dose by 28 days postcompletion of treatment. Though over half (60.7%) of the cohort reinitiated sex during follow-up¸ all reported using condoms during sex or that they and their partner were treated before sex. Six (6.7%) of 89 had a positive NAAT following their first negative NAAT. The optimal timing for T. vaginalis retesting after completion of treatment is 3 weeks for those receiving multidose MTZ and 4 weeks for those receiving single-dose, though sexual reexposure and false negatives should be considered.

Host Immune Markers Distinguish Clostridioides difficile Infection From Asymptomatic Carriage and Non-C. difficile Diarrhea.

Recent data indicate that Clostridioides difficile toxin concentrations in stool do not differentiate between C. difficile infection (CDI) and asymptomatic carriage. Thus, we lack a method to distinguish a symptomatic patient with CDI from a colonized patient with diarrhea from another cause. To address this, we evaluated markers of innate and adaptive immunity in adult inpatients with CDI (diagnosed per US guidelines), asymptomatic carriage, or non-CDI diarrhea. CDI-NAAT patients had clinically significant diarrhea and positive nucleic acid amplification testing (NAAT) and received CDI treatment. Carrier-NAAT patients had positive stool NAAT but no diarrhea. NAAT-negative patients (with and without diarrhea) were also enrolled. A panel of cytokines and anti-toxin A and B immunoglobulin (Ig) were measured in serum; calprotectin and anti-toxin B Ig A/G were measured in stool. NAAT-positive stool samples were tested by an ultrasensitive toxin assay (clinical cutoff, 20 pg/mL). Median values for interleukin (IL)-4, IL-6, IL-8, IL-10, IL-15, granulocyte colony-stimulating factor (GCSF), MCP-1, tumor necrosis factor α (TNF-α), and IgG anti-toxin A in blood and IgA/G anti-toxin B in stool were significantly higher in CDI patients compared with all other groups (P < .05). Concentration distributions for IL-6, GCSF, TNF-α, and IgG anti-toxin A in blood, as well as IgA and IgG anti-toxin B in stool, separated CDI patients from all other groups. Specific markers of innate and adaptive immunity distinguish CDI from all other groups, suggesting potential clinical utility for identifying which NAAT- and toxin-positive patients with diarrhea truly have CDI.

Predictive factors of Clostridioides difficile infection in hospitalized patients with new diarrhea: A retrospective cohort study.

Introduction and objectiveDiagnostic testing for Clostridioides difficile infection (CDI) by nucleic acid amplification test (NAAT) cannot distinguish between colonization and infection. A positive NAAT may therefore represent a false positive for infection, since diarrhea due to various aetiologies may occur in hospitalized patients. Our objective was to help answer the question: “does this medical inpatient with diarrhea have CDI?”DesignWe conducted a retrospective cohort study (n = 248) on the Clinical Teaching Units of the Royal Victoria Hospital (Montréal, Canada). Patients were included if they had a NAAT between January 2014 and September 2015 and their admission diagnosis was not CDI. CDI cases and non-CDI cases were compared, and independent predictors of CDI were determined by logistic regression.ResultsSeveral factors were independently associated with CDI, including: hemodialysis (OR: 13.5, 95% CI: 2.85–63.8), atrial fibrillation (OR: 3.70, 95% CI: 1.52–9.01), whether the patient received empiric treatment (OR: 3.01, 95% CI: 1.04–8.68), systemic antibiotic therapy prior to testing (OR: 4.23, 95% CI: 1.71–10.5), previous positive NAAT (OR: 3.70, 95% CI: 1.41–9.72), and a leukocyte count of 11x109/L or higher (OR: 3.43, 95% CI: 1.42–8.26). The area under the curve was 0.80.ConclusionFor patients presenting with hospital-onset diarrhea, various parameters can help differentiate between CDI and other causes. A clinical prediction calculator derived from our cohort (http://individual.utoronto.ca/leet/cdiff.html) might assist clinicians in estimating the risk of CDI for inpatients; those with low pre-test probability may not require immediate testing, treatment, nor prolonged isolation.

1100. Characterization of Enteropathogenic Escherichia coli (EPEC) in Cancer Patients With Diarrhea

BackgroundBiofire FilmArray multiplexed nucleic acid amplification tests (NAAT) for bacterial diarrhea include probes specific for EPEC. However, the platform does not differentiate typical EPEC (tEPEC, defined as carrying eaeA and bfp) which have strong epidemiologic associations with diarrhea from atypical EPEC (aEPEC, carrying eaeA but not bfp) for which there is a weaker association. Nevertheless, emerging data suggest that aEPEC subsets carrying efa1/lifA which encodes for adherence factor 1/lymphocyte inhibitory factor A, are associated with diarrhea. The role of EPEC and its subtypes as agents of bacterial diarrhea have not been well defined in immunosuppressed and cancer patients.MethodsWe characterized EPEC subtypes in stools from healthy individuals with no diarrhea (HI, N = 21), cancer patients with diarrhea and negative NAAT (DN, N = 25) and patients with diarrhea positive NAAT for EPEC (DP, N = 54). EPEC isolated from stool cultures were tested for eaeA and bfp, stx and other E. coli pathotypes. We estimated the number of fecal EPEC using a qPCR for eaeA, efa1/lifA that detected 5.6 × 101 to 5 × 107 cfu/mg of stool.ResultsDemographic characteristics and underlying malignancy were similar between DN and DP groups. DP were more likely to have diarrhea on admission than DN [46/52 (88%) vs. 13/25 (52%), P < 0.01]. Stool cultures confirmed EPEC in 24/52 (60%) DP of which 23/24 (96%) were aEPEC. Fecal qPCR for eaeA confirmed EPEC in 43/52 (83%) of DP, 0/25 DN and in 3/21 (14%) of HI (P < 0.001). DP excreted a higher number of EPEC cfu/mg of stool than HI (median 168 vs. 1.18 cfu/mg, P < 0.001) and only DP excreted EPEC efa1/lifA (+) [14/52 DP (27%) vs. 0/25 DN and 0/21 HI; P < 0.001]. When compared with DP EPEC efa1/lifA (-), DP EPEC efa1/lifA (+) had a longer median duration of illness (3 days vs. 1 days, P < 0.05); more likely to be hematopoietic stem cell transplant recipients [7/14 (50%) vs. 7/38 (18%), P < 0.05] and had a higher EPEC eaeA fecal burden (median 3885 vs. 84 cfu/mg, P < 0.05). Co-infections with other pathogens were equally represented in efa1/lifA (−) and efa1/lifA (+) DP subgroups [8/14 (57%) vs. 21/38 (55%) P = NS].ConclusionMost EPEC in cancer patients with diarrhea are aEPEC acquired in the community and when carrying efa1/lifA (+), are associated with more severe disease.Disclosures All authors: No reported disclosures.

Use of a Rapid Diagnostic for Chlamydia trachomatis and Neisseria gonorrhoeae for Women in the Emergency Department Can Improve Clinical Management: Report of a Randomized Clinical Trial

In emergency departments (EDs), diagnosis and treatment of Chlamydia trachomatis and Neisseria gonorrhoeae are challenging. We conducted a randomized clinical trial to assess rapid C trachomatis and N gonorrhoeae testing on overtreatment and undertreatment of women evaluated for C trachomatis and N gonorrhoeae. Women undergoing pelvic examinations and C trachomatis and N gonorrhoeae testing (n=254) were randomized to control or rapid test groups. The control group received standard-of-care C trachomatis and N gonorrhoeae nucleic acid amplification tests of endocervical specimens, with 2- to 3-day turnaround times. For the rapid test group, clinicians collected an extra endocervical swab for GeneXpert C trachomatis and N gonorrhoeae rapid testing, in addition to the standard-of-care nucleic acid amplification testswab. Rapid results were immediately provided, and all patients were treated according to providers' clinical judgment. In the rapid test group, 7.9% of patients had positive test results for C trachomatis; 3.9% had positive test results for N gonorrhoeae. In the control standard-of-care group, 10.2% of patients had positive nucleic acid amplification test results for C trachomatis; 5.5% had positive results for N gonorrhoeae. Undertreatment for both C trachomatis and N gonorrhoeae in the ED was 0% for the rapid test group and 43.8% for the control standard-of-care group. Clinicians overtreated 46.5% of uninfected standard-of-care control patients for C trachomatis compared with 23.1% of uninfected rapid test patients. For patients uninfected with N gonorrhoeae, clinicians overtreated 46.7% of standard-of-care control patients compared with 25.4% of rapid test patients. The length of stay did not differ significantly between groups. Rapid C trachomatis and N gonorrhoeae testing in the ED led to a significant reduction in overtreatment for women without infections compared with the standard-of-care control group. Additionally, in the rapid test group there was significant improvement in appropriate treatment for patients with infections.

The Role of Polymorphonuclear Leukocyte Counts from Urethra, Cervix, and Vaginal Wet Mount in Diagnosis of Nongonococcal Lower Genital Tract Infection.

Objective The aim of this study was to evaluate whether the polymorphonuclear leukocyte (PMNL) inflammatory response in women with nongonococcal lower genital tract infection (LGTI) can be used to optimize criteria for syndromic treatment. Methods A cross-sectional study of 375 women attending the STI clinic in Oslo. Urethral, cervical, and vaginal specimens underwent microscopy for PMNLs. Chlamydia trachomatis (Ct) and other STIs were detected in the cervical/vaginal swabs and urine, using nucleic acid amplification test (NAAT). After excluding vulvovaginal candidiasis, genital herpes, and trichomoniasis, we correlated clinical and microscopic signs of inflammation with positive NAAT for Ct, mycoplasma genitalium (Mg), and Ureaplasma urealyticum (Uu) in a subgroup of 293 women. Results To predict a positive Ct, the combination of high cut-off urethritis (≥10 PMNLs/HPF) and microscopic cervicitis had a high specificity of 0.93, a PPV of 0.37, and a sensitivity of 0.35. LGTI criteria had low predicting values for Mg and Uu. Conclusion Including microscopic criteria for the diagnosis of LGTI gives better indication for presumptive antibiotic treatment than anamnestic and clinical diagnosis alone.

Comparison of Clostridioides difficile Stool Toxin Concentrations in Adults With Symptomatic Infection and Asymptomatic Carriage Using an Ultrasensitive Quantitative Immunoassay.

We used an ultrasensitive, quantitative single molecule array (Simoa) immunoassay to test whether concentrations of Clostridioides (formerly Clostridium) difficile toxins A and/or B in the stool of adult inpatients with C. difficile infection (CDI) were higher than in asymptomatic carriers of toxinogenic C. difficile. Patients enrolled as CDI-NAAT had clinically significant diarrhea and a positive nucleic acid amplification test (NAAT), per US guidelines, and received CDI treatment. Potential carriers had recently received antibiotics and did not have diarrhea; positive NAAT confirmed carriage. Baseline stool samples were tested by Simoa for toxin A and B. Stool toxin concentrations in both CDI-NAAT (n = 122) and carrier-NAAT (n = 44) cohorts spanned 5 logs (0 pg/mL to >100000 pg/mL). Seventy-nine of 122 (65%) CDI-NAAT and 34 of 44 (77%) carrier-NAAT had toxin A + B concentration ≥20 pg/mL (clinical cutoff). Median toxin A, toxin B, toxin A + B, and NAAT cycle threshold (Ct) values in CDI-NAAT and carrier-NAAT cohorts were similar (toxin A, 50.6 vs 60.0 pg/mL, P = .958; toxin B, 89.5 vs 42.3 pg/mL, P = .788; toxin A + B, 197.2 vs 137.3 pg/mL, P = .766; Ct, 28.1 vs 28.6, P = .354). However, when CDI/carrier cohorts were limited to those with detectable toxin, respective medians were significantly different (A: 874.0 vs 129.7, P = .021; B: 1317.0 vs 81.7, P = .003, A + B, 4180.7 vs 349.6, P = .004; Ct, 25.8 vs 27.7, P = .015). Toxin concentration did not differentiate an individual with CDI from one with asymptomatic carriage. Median stool toxin concentrations in groups with CDI vs carriage differed, but only when groups were defined by detectable stool toxin (vs positive NAAT).

Indicators for prediction of Mycobacterium tuberculosis positivity detected with bronchoalveolar lavage fluid

BackgroundThe diagnosis of active pulmonary tuberculosis (TB) remains a challenge in clinic, especially for sputum negative pulmonary TB. Bronchoalveolar lavage fluid (BALF) has higher sensitivity than sputum for detection of Mycobacterium tuberculosis (Mtb). However, bronchoscopy is invasive and costly, and not suitable for all patients. In order to make TB patients get more benefit from BALF for diagnosis, we explore which indicator might be used to optimize the choice of bronchoscopy.MethodsA total of 1539 sputum-smear-negative pulmonary TB suspects who underwent bronchoscopy were recruited for evaluation. The sensitivity, specificity and accuracy of Mtb detection in sputum and BALF were compared. Odds ratios and 95% confidence intervals were used to assess variables that associated with positive acid-fast bacilli (AFB) smear, Mtb culture and nucleic acid amplification test (NAAT) of BALF in sputum-negative and non-sputum-producing pulmonary TB suspects.ResultsBALF has significantly higher sensitivity (63.4%) than sputum (43.5%) for Mtb detection by culture and NAAT. 19.7% (122/620) sputum-negative and 40.0% (163/408) non-sputum-producing suspects had positive bacteriological results in BALF. Among sputum-negative and non-sputum-producing pulmonary TB suspects, the positivity of Mtb detection in BALF is associated with a younger age, the presence of pulmonary cavities and a positive result of interferon-gamma release assay (IGRA). Sputum-negative patients under 35 years old with positive IGRA and pulmonary cavity had 84.8% positivity of Mtb in BALF.ConclusionsOur study indicated that combination of age, the presence of pulmonary cavity, and the result of IGRA is useful to predict the positivity of Mtb detection in BALF among sputum-negative and non-sputum producing pulmonary TB suspects. Those who are under 35 years old, positive for the presence of pulmonary cavity and IGRA, should undergo bronchoscopy to collect BAFL for Mtb tests, as they have the highest possibility to get bacteriologically confirmation of TB.

Enzyme Immunoassay for C. difficile Toxin Reduces Lab ID Events but Fails to Detect Clinically Significant C. difficile Infection

BackgroundThe National Health Safety Network (NHSN) requires reporting of Lab ID events for C. difficile infection (CDI) including all positive clinical tests after day three of hospitalization. Nucleic acid amplification tests (NAAT) that detect genes for toxins A and/or B may be overly sensitive, in some cases detecting C. difficile colonization. Some have advocated for two-stage testing, with positive NAAT tests followed by confirmatory enzyme immunoassay (EIA) to detect the presence of toxin and minimize the downside of false positives (i.e. additional NHSN reports or overuse of antibiotics). We aimed to better understand clinical characteristics of patients with positive NAAT and/or EIA tests.MethodsOur hospital uses Xpert C. difficile assay (Cepheid), a NAAT method utilizing polymerase chain reaction (PCR), to diagnose CDI on unformed stool only. As part of a 6 month quality initiative, we pilot tested the C.DIFF QUIK CHEK COMPLETE® test (Alere), an EIA that tests for C. difficileantigen (Ag) and toxin, on all specimens that tested positive by NAAT. We abstracted clinical data from the medical record for a subset of patients who underwent EIA testing.ResultsOver 6 months, 294 patients had a positive test by NAAT. Of these, 258 (87.8%) underwent EIA testing. 67 (26.0%) were Ag+/toxin+, 173 (67.1%) were Ag+/toxin-, and 18 (6.8%) were Ag-/toxin-. Mortality rates were as follows: Ag+/toxin+, 17.9% (12/67); Ag+/toxin-, 13.9% (24/173); Ag-/toxin-, 27.8% (5/18), P = 0.27. Among the EIA toxin negative patients who underwent chart review, 81% had 3 or more loose stools within 24 hours, 62% had abdominal pain, nausea, or vomiting, and 27% had a WBC > 15.ConclusionThe majority of patients testing positive for CDI by NAAT had a negative EIA test for toxin. There was no significant difference in mortality between EIA toxin positive and negative. Those with negative EIA toxin tests often had clinically significant symptoms of CDI. A two-stage CDI testing algorithm with NAAT followed by EIA for toxin may exclude patients with clinically significant CDI but would have resulted in a 75% reduction in reported NHSN LabID events.Disclosures All authors: No reported disclosures.

Line of Service-Specific Performance and Antibiotic Prescribing Habits Following Introduction of a Two-Step Diagnostic Approach Using NAAT Followed by Enzyme Immunoassay in Cancer Patients with Suspected Clostridium difficile Infection

BackgroundPatients with cancer are at an increased risk for C. difficile infection (CDI). A two-step approach with a Nucleic Acid Amplification Test (NAAT) followed by enzyme immunoassay (EIA) increases diagnostic sensitivity and specificity and can be used to guide antibiotic therapy. We retrospectively investigated the relative performance of the two-step approach in cancer patients with solid tumors (ST), hematologic malignancies (HS), and hematopoietic stem cell transplant recipients (HSCT).MethodsWe identified 204 patients with a positive NAAT test for CDI as determined by GI multiplex (Biofire) or by Illumigene (Meridian, Bioscience) in whom a reflex EIA was performed for C. difficile A/B toxins between November 2015 and February 2017. Patients were stratified into ST, HM, HSCT groups. We compared the proportion of discordant NAAT+, EIA- results among the three groups. We then compared the clinical presentation and antibiotic use for patients in the NAAT+/EIA- to those with NAAT+/EIA+ results.ResultsOverall an EIA+ result was found in 53 (26%) patients. The proportion of patients with NAAT+/EIA+ results was significantly different between the three lines of service; ST 31/86 (36%), HM 16/62 (26%), and HSCT 6/56 (11%) P < 0.01. A trend towards a higher proportion of positive results was observed for ST compared with the HM group (P = 0.06). Results were similar between the HM and HSCT group. However, patients in the ST were more likely to have a positive EIA when compared with HSCT patients (36% vs. 11% P < 0.01). Clinical presentation and healthcare-association were similar in all three groups regardless of the EIA result. Despite the low proportion of EIA+ confirmatory results, the majority of patients (196/204 96%) received antibiotic therapy targeting CDI. Discontinuation of CDI antibiotics prior to 10 days of therapy was similar in the EIA+ (12%) vs. EIA- (10%).ConclusionThe relevance of discordant results needs to be interpreted in the context of the line of service/patient care unit. The presence of CDI as determined by NAAT/EIA is low in patients with other potential causes of diarrhea such as in HSCT recipients. A substantial proportion of cancer patients are treated unnecessarily for CDI.Disclosures All authors: No reported disclosures.

Staff, associate specialist and specialty doctors' national audit on the management of gonorrhoea in the United Kingdom, 2015.

The British Association for Sexual Health and HIV (BASHH) revised United Kingdom national guideline for the management of gonorrhoea in adults, 2011, identified five auditable outcome measures, namely, that all patients should receive first-line treatment, be screened or treated for chlamydial infection, have a test of cure (TOC), be offered written information and have partner notification carried out. The UK National Guideline for Gonorrhoea Testing, Clinical Effectiveness Group, BASHH, 2012, recommended in addition that all reactive nucleic acid amplification tests (NAATs) from pharynx and rectum should be confirmed by supplementary testing, using a second NAAT which detects a different nucleic acid target, all those with a positive NAAT for gonorrhoea should have culture and antimicrobial susceptibility testing and that TOC should be done by two weeks. Staff, associate specialist and specialty doctors performed a national audit against these standards. Data from 3233 cases were submitted; 8% of cases of gonorrhoea diagnosed in England, Scotland and Wales over this period. We found that 83% patients received first-line treatment with a reason for not doing so provided for 11%. TOC was documented for 62% and written information was offered to 41%. Results about supplementary testing were inconsistent. The results for the other outcomes were satisfactory.

Diagnosis and outcome of Clostridium difficile infection by toxin enzyme immunoassay and polymerase chain reaction in an island population.

Clostridium difficile infection (CDI) is a potentially life-threatening cause of diarrhea. Correct laboratory diagnosis is essential to differentiate CDI from other causes of diarrhea. A positive fecal C. difficile toxin (CDT) is the best indicator of CDI, but the significance of a positive fecal nucleic acid amplification test (NAAT) remains unclear. Our aim was to elucidate the significance of CDI diagnostics in patients in Jersey. A retrospective, 5-year study was conducted at an island district general hospital of patients who developed CDI. Patients were grouped according to CDT and NAAT status and their association with outcome (indicators of severity and 30-day case-fatality rate) compared. A total of 207 specimens were toxin positive, 92 NAAT positive and toxin negative, and 39 had a stool sample negative by both toxin and NAAT testing. A positive toxin stool sample was associated with both significantly higher white cell count (14.5 × 109 /L vs 11.3 × 109 /L, P = 0.003) and C-reactive protein (114.7 mg/dL vs 82.9 mg/dL, P = 0.001), but NAAT positivity was not (P = 0.269, 0.728). A positive CDT assay was a significant independent predictor of death (odds ratio [OR]: 1.89 [95% CI: 1.04-3.43], P = 0.046), but a positive NAAT in CDT negative samples was not (OR: 1.02 [95% CI: 0.34-3.12], P = 1.0). The findings of this study, derived from evolving clinical practice, provide greater clarity in the interpretation of CDI diagnostics. In CDT-negative disease, a positive NAAT neither predicts disease severity nor mortality. NAAT-positive and toxin-negative patients require instigation of infection control measures, but the need for specific treatment remains unclear.

The validation and evaluation of anti-HIV testing algorithm used in mobile clinic setting for men who have sex with men in metropolitan Bangkok, Thailand

Same-day anti-HIV testing algorithm is recommended by Thai National Guidelines. We compared performance characteristics of algorithms used in a mobile clinic and a facility-based clinic for men who have sex with men (MSM) in Bangkok. Mobile clinic samples collected from 4 saunas and 2 spa venues were tested by Alere DetermineTM HIV 1/2, followed by DoubleCheck GoldTM Ultra HIV 1/2 and SD Bioline HIV 1/2 3.0. All samples were re-tested at the Thai Red Cross Anonymous Clinic (TRCAC) by Architect HIV Ag/Ab or Elecsys HIV combi PT, followed by Alere DetermineTM HIV 1/2 and Serodia HIV 1/2. Non-reactive samples were tested by Aptima nucleic acid amplification test (NAAT) and reactive/inconclusive samples were tested by less-sensitive immunoassays (IA) and HIV-1 RNA to detect acute HIV infection (positive NAAT or non-reactive IA/positive HIV-1 RNA). Of 233 MSM, 36 (15.5%) had HIV infection diagnosed using mobile clinic algorithm. Two additional acute HIV cases (1 positive NAAT and 1 reactive Architect with detectable HIV-1 RNA) were diagnosed using TRCAC algorithm. The mobile clinic algorithm had a sensitivity of 94.9% (95% CI: 82.7, 99.4) and a specificity of 100% (95% CI: 98.1, 100). Use of whole blood on rapid test kits demonstrated satisfactory performance and allowed same-day HIV test result through a mobile clinic model. For populations with high HIV incidence, careful history taking to define the window period is crucial and repeat testing must be encouraged if the testing algorithm does not include 4th generation anti-HIV assay or NAAT.

Excluding Anti-cytomegalovirus Immunoglobulin M-Positive Cord Blood Units Has a Minimal Impact on the Korean Public Cord Blood Bank Inventory

Cord blood units (CBUs) for transplantation should be free of communicable disease and must contain a specific amount of total nucleated cells and CD34+ cells. Although posttransplantation cytomegalovirus (CMV) infections are from latent infection in patients, ensuring CMV-free CBUs by performing CMV-specific IgM and nucleic acid amplification testing (NAT) is one of the mandatory procedures for the safety of CBUs. However, the exclusion policies (based on these test results) vary among nations and institutions. We tested 28,000 processed CBUs between May 2006 and June 2014. The cord blood leukocytes from CMV IgM-positive samples were then subjected to NAT. The total nucleated cell and CD34+ cell counts were measured for each CBU, and the results were compared to the CMV IgM and IgG results. The seroprevalence of CMV among pregnant women was 98.1% (18,459/18,818) for IgG and 1.7% (441/25,293) for IgM. The concentration and the total number of CD34+ cells were significantly higher in CBUs from IgM-negative mothers compared to those from IgM-positive mothers (72.4/μl vs. 57.2/μl, respectively, p < 0.0001; 1.45 × 106/unit vs. 1.15 × 106/unit, respectively, p < 0.0001). Among CBUs with positive CMV IgM in their mothers' plasma or cord blood plasma, only 0.58% of the samples (3/517) had a positive NAT. The number of excluded CBUs from inventory due to positive CMV IgM in the cord blood was 54 of 18,326 (0.3%). For inventory purposes, it is appropriate to remove CBUs with positive cord blood CMV IgM findings irrespective of the NAT status as well as positive maternal CMV IgM in South Korea.

P202 The acceptability of self-sampling at home forChlamydia trachomatisandNeisseria gonorrhoeaein men and women; results from the feasibility study to determine the time taken for NAATs tests to become negative following treatment forChlamydia trachomatisandNeisseria gonorrhoeaein men and women

Background/introduction Self-sampling with nucleic acid amplification tests(NAATs) for detection of chlamydia(CT) and gonorrhoea(NG) is increasingly being used in clinics, with much success. There is some data to suggest that it is acceptable to patients. Aim(s)/objectives To assess symptoms, sexual behaviour and the acceptability of self-taken swabs for CT and NG, among participants in the ‘Time to test of cure study for CT and NG’. Methods Individuals who had a positive NAAT test for CT and/or NG were eligible. Self-taken specimens from the site of infection were collected at home. Data about sexual behaviour, symptoms and acceptability of home testing with self-taken samples was collected from questionnaires. Results 102 men (87 MSM) and 52 women were recruited to the study, 84 had NG infection and 71 had CT infection. The median age was 28 years. Unprotected sexual intercourse in the last month was reported by 68% of MSM, 56% of heterosexual men and 51% of women. Symptoms were reported by 25% of MSMs, 50% of heterosexual men and 51% of women. 86% of participants found the information clear and easily understandable. 85% felt confident taking their own samples. 58% found the samples easy to take, 75% were happy to take their own swabs and 78% were happy to take samples at home. Discussion/conclusion This data highlights the need for screening of asymptomatic patients and provides data to support that self-taken sampling is acceptable to patients. It also provides evidence to support home testing for CT and NG. Therefore allowing for greater access to testing and treatment and reducing the burden of infection in the community.

O023 Feasibility study to determine the time taken for NAATs tests to become negative following treatment forChlamydia trachomatisandNeisseria gonorrhoeaein men and women

Background/introduction Few data are available to guide the best time to perform a test of cure using nucleic acid amplification tests (NAATs) following treatment for chlamydia (CT) and gonorrhoea (NG). Aim(s)/objectives The association between the type of infection, organism load, site of infection and treatment were compared to the time for the NAAT to become negative after treatment. Methods Individuals who had a positive NAAT test for CT and/or NG were eligible. Self-taken specimens from the site of infection were collected at 8 time points.The time to first negative test following treatment was examined using survival analysis techniques. Results 102 men (87 MSM) and 52 women were recruited to the study (84 NG, 71 CT infections). 28 participants with NG and 16 with CT were lost to follow up. On day 0, 20 participants diagnosed with NG and 8 diagnosed with CT had negative tests. Median time to negativity for NG infection was 2 days (IQR 1–5) and for CT infection was 4 days (IQR 2–5). At day 14 after treatment 92% of participants were CT negative, and 84% NG negative.All tests were negative by day 35 for both infections. Discussion/conclusion This study provides valuable data in determining the time to test of cure for CT and NG infections. Site of infection may have an effect on time to clearance of infection, with pharyngeal NG infections and vaginal CT infections taking longer to clear than other sites.The results of this study will help guide clinicians to the timing for test of cure.