Nonculture Tests Research Articles

Progress on nonculture based diagnostic tests for invasive mould infection.

This review describes the current status of diagnosing invasive mould disease and Pneumocystis pneumonia using nonconventional diagnostics methods. There has been significant development in the range of nonculture mycological tests. Lateral flow tests (LFTs) for diagnosing aspergillosis complement galactomannan ELISA testing, and LFTs for other fungal diseases are in development. Rapid and low through-put B-D-Glucan assays increase access to testing and there has been significant progress in the standardization/development of molecular tests. Despite this, no single perfect test exists and combining tests (e.g., antigen and molecular testing) is likely required for the optimal diagnosis of most fungal diseases. Based on established clinical performance few mycological tests can be used alone for optimal diagnosis of fungal disease (FD) and combining tests, including classical approaches is the preferred route for confirming and excluding disease. Next-generation sequencing will likely play an increasing role in how we diagnose disease, but optimization, standardization and validation of the entire molecular process is needed and we must consider how host biomarkers can stratify risk. Given the burden of FD in low- and medium-income countries, improved access to novel but more so existing diagnostic testing is critical along with simplification of testing processes.

Current microbiological testing approaches and documented infections at febrile neutropenia onset in patients with hematologic malignancies

ObjectivesThis study aims to identify infection etiology in febrile neutropenia (FN) is vital. This study explores different microbiological approaches and their impact on diagnosing infections in patients with hematologic malignancies and FN. MethodsThis is a retrospective analysis conducted at the Hospital Clinic of Barcelona details microbiological testing strategies used to diagnose infections at FN onset between January 2020 and July 2022. ResultsA total of 4520 microbiological tests were ordered in 462 FN episodes, achieving a 10% test positivity rate, with 200 (43.3%) episodes showing microbiological documentation of infection. Blood cultures (40.4%), non-culture blood tests (21.2%), and respiratory tract samples (16.2%) were the most requested. Blood cultures exhibited the highest (16.9%) test positivity rates, whereas non-culture blood tests showed the lowest (3.3%). Bacterial infections were present in 149 of 462 (32.3%) FN episodes. Viral infections (66 of 462, 14.3%)—notably, respiratory viruses—were also frequent. Mortality rate at 60 days was 9.1%; documented infections were associated with a higher risk (15%). ConclusionsIn the current landscape of antimicrobial diagnostics, our findings revealed the highest reported rate of microbiologically documented infections at FN onset. Bacterial infections are common; however, our data reiterate the significance of viral infections in causing fever. Optimizing FN management during respiratory viral infections remains a challenge for antimicrobial de-escalation. The low positivity rates observed in certain diagnostic tests emphasize the need for cost-effective diagnostic stewardship.

Factors associated with tracheostomy-associated infection treatment: A multicenter observational study.

To characterize factors that influence the decision to treat suspected pediatric bacterial tracheostomy-associated respiratory infections (bTRAINs; e.g., pneumonia, tracheitis). We conducted a multicenter, prospective cohort study of children with pre-existing tracheostomy hospitalized at six children's hospitals for a suspected bTRAIN (receipt of respiratory culture plus ≥1 doses of an antibiotic within 48 h). The primary predictor was respiratory culture growth categorized as Pseudomonas aeruginosa, P. aeruginosa + ≥1 other bacterium, other bacteria alone, or normal flora/no growth. Our primary outcome was bTRAIN treatment with a complete course of antibiotics as documented by the discharge team. We used logistic regression with generalized estimating equations to identify the association between our primary predictor and outcome and to identify demographic, clinical, and diagnostic testing factors associated with treatment. Of the 440 admissions among 289 patients meeting inclusion criteria, 307 (69.8%) had positive respiratory culture growth. Overall, 237 (53.9%) of admissions resulted in bTRAIN treatment. Relative to a negative culture, a culture positive for P. aeruginosa plus ≥1 other organism (adjusted odds ratio [aOR] 2.3; 95% confidence interval [CI] 1.02-5.0)] or ≥1 other organism alone (aOR: 2.8; 95% CI: 1.4-5.6)] was associated with treatment. Several clinical and diagnostic testing (respiratory Gram-stain and chest radiograph) findings were also associated with treatment. Positive respiratory viral testing was associated with reduced odds of treatment (aOR: 0.5; 95% CI: 0.2-0.9). Positive respiratory cultures as well as clinical indicators of acute illness and nonculture test results were associated with bTRAIN treatment. Clinicians may be more comfortable withholding antibiotics when a virus is identified during testing.

Stewardship-Guided T2Candida Testing Shortens Time to Antifungal Treatment and Reduces Antifungal Usage Among Medical Intensive Care Unit Patients With Septic Shock.

Diagnosis of invasive candidiasis (IC) is limited by insensitivity and slow turnaround of cultures. Our objectives were to define the performance of T2Candida, a nonculture test, under guidance of a diagnostic stewardship program, and evaluate impact on time to antifungal initiation and antifungal utilization. This was a retrospective study of adult medical intensive care unit (MICU) patients with septic shock for whom T2Candida testing was performed from March 2017 to March 2020. Patients with positive T2Candida results during this period were compared to MICU patients who did not undergo T2Candida testing but had septic shock and blood cultures positive for Candida from January 2016 through March 2020. Overall, 155 T2Candida tests from 143 patients were included. Nine percent of T2Candida tests were positive compared to 4.5% of blood cultures. Sensitivity, specificity, positive predictive value, and negative predictive value of T2Candida for proven and probable IC were 78%, 95%, 50%, and 99%, respectively. Patients who tested positive for T2Candida (n = 14) were diagnosed earlier and initiated on antifungal therapy sooner than patients with IC (n = 14) diagnosed by blood culture alone (median, 5.6 vs 60 hours; P < .0001). Median antifungal days of therapy/1000 patient-days were 23.3/month preimplementation and 15/month postimplementation (P = .007). Following a negative T2Candida result, empiric antifungals were either not administered in 58% or discontinued within 72 hours in 96% of patients. Diagnostic stewardship guided T2Candida testing resulted in reduced time to IC diagnosis, faster initiation of antifungal therapy, and lower antifungal usage among MICU patients with septic shock.

Loop-Mediated Isothermal Amplification Assay for Identifying Neisseria gonorrhoeae Nonmosaic penA-Targeting Strains Potentially Eradicable by Cefixime.

ABSTRACTTreatment regimens for gonorrhea have limited efficacy worldwide due to the rapid spread of antimicrobial resistance. Cefixime (CFM) is currently not recommended as a first-line treatment for gonorrhea due to the increasing number of resistant strains worldwide. Nonetheless, Neisseria gonorrhoeae strains can be eradicated by CFM at a 400 mg/day dose, provided that the strains are CFM responsive (MIC ≤ 0.064 mg/L). To develop a nonculture test for predicting the CFM responsiveness of N. gonorrhoeae strains, we developed an assay to detect N. gonorrhoeae nonmosaic penA using loop-mediated isothermal amplification (LAMP). To avoid false-positive reactions with commensal Neisseria spp. penA, we amplified specific regions of the N. gonorrhoeae penA (NG-penA-LAMP1) and also the nonmosaic N. gonorrhoeae penA (NG-penA-LAMP3). This assay was validated using isolated N. gonorrhoeae (n = 204) and Neisseria spp. (n = 95) strains. Clinical specimens (n = 95) with confirmed positivity in both culture and real-time PCR were evaluated to validate the system. The combination of the previously described NG-penA-LAMP1 and our new NG-penA-LAMP3 assays had high sensitivity (100%) and specificity (100%) for identifying N. gonorrhoeae carrying the nonmosaic type. To determine whether CFM could be applicable for gonorrhea treatment without culture testing, we developed a LAMP assay that targets penA allele-specific nonmosaic types for use as one of the tools for point-of-care testing of antimicrobial resistance.IMPORTANCE Neisseria gonorrhoeae is among the hot topics of “resistance guided therapy,” one of the top 5 urgent antimicrobial threats according to the Centers for Disease Control and Prevention (CDC). There is a need either to develop new agents or to make effective use of existing agents, with the current limited number of therapeutic agents available. Knowing the drug susceptibility information of the target microorganism prior to treating patients is very useful in selecting an effective antibiotic, especially in gonococcal infections where drug resistance is prominent, and is also important in preventing treatment failure. In this study, we developed a new method for obtaining drug susceptibility profiles of Neisseria gonorrhoeae using the loop-mediated isothermal amplification (LAMP) method. The LAMP assay does not require expensive devices. Therefore, this method is expected to be a tool for point-of-care testing of antimicrobial resistance for individualized treatment in the future.

Evaluation of a Newly Developed Non-Culture Test for Bacteriological Diagnosis of Ventilator-Associated Pneumonia in RMCH

Background: The diagnosis and treatment of pneumonia in patients who are receiving mechanical ventilation remain adifficult challenge. Objective: To investigate the utility of soluble triggering receptor expressed on myeloid cells1(s TREM-1) levels inEndotracheal aspirate (ETA) samples as early biomarkers for the diagnosis of VAP compared with quantitative culture result ofETA. Methods: A total of eighty patients with clinically suspected VAP cases were included in this study and were selectedpurposely. ETA was collected and level Wes TREM-1are measured. On the other hand, VAP was diagnosed by the quantitativeculture of ETA. Results: The concentration of s TREM-1 in ETA did not discriminate VAP positive from VAP negative patients whencompared to quantitative cultures of ETA as the gold standard. A cut-off value of 68.72pg/ml for human s TREM1 in ETAresulted in a sensitivity of 60.81% and specificity of 62.5%. Conclusion: It may be concluded that the proposed ELISA kit cannot be used as a rapid diagnostic test for the immediatediagnosis of VAP.

Nosocomial pneumonia diagnosis revisited.

Nosocomial pneumonia represents a significant burden even for the most resilient healthcare systems. Timely and reliable diagnosis is critical but remains a deficient field. This review critically revises the latest literature on the diagnosis of nosocomial pneumonia, including advances in imaging techniques, as well as the utility of rapid microbiological tests in establishing the etiological diagnosis. Studies on low radiation computed tomography (CT) and lung ultrasound (LUS) have shown promising results for early nosocomial pneumonia diagnosis; however, further data on their sensitivity and specificity are needed, especially for picking up subtle and nonspecific radiographic findings. Moreover, data supporting their superiority in pneumonia diagnosis is still limited. As for microbiological diagnosis, several culture-independent molecular diagnostic techniques have been developed, identifying both causative microorganisms as well as determinants of antimicrobial resistance, but more studies are needed to delineate their role in nosocomial pneumonia diagnosis. The development of nonculture dependent tests has launched a new era in microbiological nosocomial pneumonia diagnosis. These modalities along with the use of LUS and/or low radiation CT might improve the sensitivity and specificity of nosocomial pneumonia diagnosis, enhance early detection and guide the antimicrobial therapy but more studies are needed to further evaluate them and determine their role for the routine clinical practice.

Blind Spots of Traditional Microbiological Tests for Severe Community-Acquired Pneumonia in Adults and Availability of Nonculture Techniques: A Nationwide Survey of Physicians in China

In China, no national survey has been conducted to evaluate physicians' attitudes and compliance with guidelines in the management of adult patients with community-acquired pneumonia (CAP). Therefore, this study aimed to evaluate physicians' awareness of the use of microbiological tests in the management of severe CAP (SCAP) and to investigate the availability of nonculture tests in China. A nationwide electronic questionnaire survey was conducted among Chinese physicians between March and July 2018, which assessed their viewpoints concerning the issues in the management of SCAP. A total of 6333 physicians completed this survey, evenly covering all career stages. Among these, 3208 (50.6%) and 1936 (30.6%) had blind spots in the application of blood and sputum cultures in the management of SCAP, respectively. Nonteaching hospital, nonrespirologists, and junior career stage were independently associated with misunderstandings. Regarding nonculture methods, 52.7% of the facilities had no access to polymerase chain reaction-based pathogen detection tests. The accessibility of urinary antigen tests for Streptococcus pneumoniae (42.5%) and Legionella pneumophila (38.5%) was also low. The main barriers were inland and remote region, lower hospital level, and nonteaching hospital. Insufficient use of sputum and blood cultures, together with low accessibility of major nonculture techniques, were noticeable barriers to achieving microbiological diagnosis of SCAP in China. To help curb the overuse of broad-spectrum antibiotics, further measures should be taken to raise awareness among nonspecialists and promote rapid nonculture tests, especially in nonteaching hospitals and developing regions.

Role of Non-Culture Tests for the Diagnosis of Invasive Fungal Infections

Invasive fungal infection (IFI) is a condition that develops among immunosupressed patients particularly and requires the prompt diagnosis and treatment. Histopathological examination and culture are the gold standards for the diagnosis, but difficulties in sampling and shortcomings of culture mandate use of easier and faster methods. Nowadays, molecular tests such as polymerase chain reaction are […]

Assessment of Diagnostic Yield of Nonculture Infection Testing on Cerebrospinal Fluid in Immune-Competent Children

Nonculture infection tests of cerebrospinal fluid (CSF) samples using polymerase chain reaction and antigen or antibody assays are frequently ordered on lumbar puncture specimens concurrently with routine CSF cell counts, but the value of CSF infection testing in otherwise healthy children is unknown. To determine the value of nonculture CSF infection testing in immune-competent children with normal CSF cell counts. This cross-sectional study reviewed screening and diagnostic tests in the electronic medical record system of a large academic tertiary care children's hospital. Records of children aged 0.5 to 18.9 years (n = 4083) who underwent lumbar puncture (n = 4811 procedures) in an inpatient or outpatient facility of Children's Hospital of Philadelphia between July 1, 2007, and December 31, 2016, were reviewed. Those with indwelling CSF shunts or catheters; those with active or past oncologic, immunologic, or rheumatologic conditions; or those taking immune-suppressing medications were excluded from analysis. This study was conducted from July 20, 2017, to March 13, 2019. Outcome variables included frequency of nonculture CSF infection testing and frequency of positive results in the entire cohort, and among those with normal cell counts. Normal cell counts were defined as CSF white blood cell counts lower than 5 cells/μL and CSF red blood cell counts lower than 500 cells/μL. In total, 4811 lumbar puncture procedures were performed on 4083 unique children, with a median (range) age of 7.4 (0.5-18.9) years, 2537 boys (52.7%), and 3331 (69.2%) with normal CSF cell counts. At least 1 nonculture CSF infection test was performed on 1270 lumbar puncture specimens with normal cell counts (38.1%; 95% CI, 36%-40%), and more tests were performed in the summer months. Only 18 (1.4%; 95% CI, 0.9%-2.2%) of 1270 lumbar puncture specimens with normal cell counts had at least 1 nonculture infection test with a positive result; 2 of these 18 children required clinical intervention for their positive results, but each also had other clear clinical signs of infection. Nonculture CSF infection testing appeared to be common in immune-competent children with normal CSF cell counts, but positive results were uncommon and were not independently associated with clinical care; delaying the decision to send nonculture infection tests until CSF cell counts are available could reduce unnecessary diagnostic testing and medical costs, which may improve value-based care.

Performance of the T2Bacteria Panel for Diagnosing Bloodstream Infections: A Diagnostic Accuracy Study.

Blood cultures, the gold standard for diagnosing bloodstream infections (BSIs), are insensitive and limited by prolonged time to results. The T2Bacteria Panel (T2 Biosystems) is a direct-from-blood, nonculture test that identifies the most common ESKAPE bacteria (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli). To assess performance of the T2Bacteria Panel in diagnosing suspected BSIs in adults. Prospective patient enrollment (8 December 2015 through 4 August 2017). Eleven U.S. hospitals. 1427 patients for whom blood cultures were ordered as standard of care. Paired blood culture and T2Bacteria testing. Performance of T2Bacteria compared with a single set of blood cultures in diagnosing proven, probable, and possible BSIs caused by T2Bacteria-targeted organisms. Blood culture and T2Bacteria results were positive for targeted bacteria in 3% (39 of 1427) and 13% (181 of 1427) of patients, respectively. Mean times from start of blood culture incubation to positivity and species identification were 38.5 (SD, 32.8) and 71.7 (SD, 39.3) hours, respectively. Mean times to species identification with T2Bacteria were 3.61 (SD, 0.2) to 7.70 (SD, 1.38) hours, depending on the number of samples tested. Per-patient sensitivity and specificity of T2Bacteria for proven BSIs were 90% (95% CI, 76% to 96%) and 90% (CI, 88% to 91%), respectively; the negative predictive value was 99.7% (1242 of 1246). The rate of negative blood cultures with a positive T2Bacteria result was 10% (146 of 1427); 60% (88 of 146) of such results were associated with probable (n= 62) or possible (n= 26) BSIs. If probable BSIs and both probable and possible BSIs were assumed to be true positives missed by blood culture, per-patient specificity of T2Bacteria was 94% and 96%, respectively. Low prevalence of positive blood cultures, collection of a single set of culture specimens, and inability of T2Bacteria to detect nontargeted pathogens. The T2Bacteria Panel rapidly and accurately diagnoses BSIs caused by 5 common bacteria. T2 Biosystems.

Evaluation of an overnight non-culture test for detection of viable Gram-negative bacteria in endoscope channels.

Background and study aims Prevention of infection transmission from contaminated endoscopes would benefit from a rapid test that could detect low levels of viable bacteria after high level disinfection. The aim of this study was to evaluate the rapid NOW! (RN) test’s ability to detect endoscope contamination. Materials and methods The RN test kit and the accompanying fluorometer were evaluated. The manufacturer states that a fluorometer signal > 300 units is indicative of viable Gram-negative bacteria. Suspension testing of varying concentrations of Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis were used to determine the RN test limit of detection. Simulated-use testing was done using a duodenoscope inoculated with 10 % blood containing approximately 35 CFU E. coli per channel. Samples were extracted from the duodenoscope instrument channel and tested using the manufacturer’s instructions. Results The RN test could consistently detect 10 CFU of E. coli and P. aeruginosa (fluorescent signal of 9,000 to 11,000 units) but not E. faecalis. Sensitivity and specificity for Gram-negative bacteria were 93 % and 90 %, respectively, using all of the suspensions in the study. Extraction of E. coli from an inoculated duodenoscope instrument channel repeatedly provided a positive signal (i. e. > 2,000 units). Conclusions The RN test can reliably detect low levels of Gram-negative bacteria in suspension as well as from samples extracted from endoscope channels. These preliminary findings are encouraging but further assessment of extraction efficacy, impact of organic residuals and clinical workflow are still needed.

Diagnosing Invasive Candidiasis.

Cultures are negative in ∼50% of invasive candidiasis. Data are emerging for the performance of nonculture tests such as mannan/antimannan, Candida albicans germ tube antibody, 1,3-β-d-glucan, PCR, and the T2Candida panel in diagnosing both candidemia and deep-seated candidiasis. In most settings, positive predictive values of nonculture test are low, and negative predictive values are high. For tests to be useful, clinicians must understand the pretest likelihood of invasive candidiasis and test performance for the most common disease manifestation in a given patient. This paper reviews nonculture Candida diagnostics and discusses how they might be used effectively in patient care.

Non-Culture Diagnostics for Invasive Candidiasis: Promise and Unintended Consequences.

Blood cultures are positive for Candida species in < 50% and < 20% of hematogenously disseminated and intra-abdominal candidiasis, respectively. Non-culture tests such as mannan, anti-mannan antibody, Candida albicans germ tube antibody (CAGTA), 1,3-β-d-glucan (BDG), the T2Candida nanodiagnostic panel, and polymerase chain reaction (PCR) are available for clinical use, but their roles in patient care are uncertain. Sensitivity/specificity of combined mannan/anti-mannan, BDG, T2Candida and PCR for candidemia are ~80%/80%, ~80%/80%, ~90%/98%, and ~90%/90%, respectively. Limited data for intra-abdominal candidiasis suggest CAGTA, BDG sensitivity/specificity of ~65%/75% and PCR sensitivity of ~85–90%. PCR specificity has varied widely for intra-abdominal candidiasis (33–97%), and T2Candida data are lacking. Tests will be useful if restricted to cases in which positive and negative predictive values (PPVs, NPVs) differ in a clinically meaningful way from the pre-test likelihood of invasive candidiasis. In some patients, PPVs are sufficient to justify antifungal treatment, even if blood cultures are negative. In most patients, NPVs of each test are excellent, which may support decisions to withhold antifungal therapy. If test results are not interpreted judiciously, non-culture diagnostics may have unintended consequences for stewardship and infection prevention programs. In particular, discrepant non-culture test-positive/culture-negative results may promote inappropriate antifungal treatment of patients who are unlikely to have candidiasis, and lead to spurious reporting of hospital-acquired infections. In conclusion, non-culture Candida diagnostics have potential to advance patient care, but this promise will be realized only if users understand tests’ strengths and limitations, and plan proactively for how best to employ them at their hospitals.

Effects of biocide exposure on P. Aeruginosa, E. coli and A. Baumannii complex isolates from hospital and household environments

Background: Bacterial responses to biocide exposure and its effects on survival and persistence remain to be studied in greater detail.Aim: To analyse the viability and survival of environmental isolates from household and hospital settings after biocide exposure.Methods: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of chlorhexidine (CHxG), benzalkonium chloride (BAC) and triclosan (TC) were determined in isolates of Pseudomonas aeruginosa, Acinetobacter baumannii complex and Escherichia coli collected from hospital and households environments. Viability was monitored after exposure and removal of biocides using agar cultures and flow cytometry.Findings: P. aeruginosa isolates showed greater tolerance for all biocides tested whereas A. baumannii complex and E. coli were less tolerant.When compared with reference strains, biocide tolerance was up to 8 to 13-fold higher for TC and BAC respectively. Flow cytometry showed that biocide exposure may induce viable but non-growing states in P. aeruginosa and E. coli isolates before becoming fully replicative. Changes in the susceptibility profile in one isolate of A. baumannii complex were observed after biocide exposure.Discussion: Bacteria isolates from hospital and households were able to recover after biocide exposure at bactericidal concentrations favouring persistence and spread of biocide-tolerant strains. This study reinforces that cleaning compliance should be monitored by non-culture based tests. Novel formulations in cleaning and disinfection protocols should be revisited in hospitals harbouring P. aeruginosa and A. baumannii multidrug resistant isolates.

Culture-Positive Pulmonary Aspergillosis Infection: Clinical and Laboratory Features of Solid-Organ Transplant Recipients.

Aspergillosis is a common fungal infection among solid-organ transplant recipients. Even after awareness of this infection occurs, there are still gaps in nonculture diagnostic tests, which can delay treatment initiation. Here, we aimed to define the common traits of pulmonary aspergillosis infection among solid-organ transplant recipients, thus shedding light on prevention and early diagnosis. We conducted a database search of patients at Baskent University who had a positive aspergillosis culture between January 2010 and March 2016. Among 20 patients identified, 15 (mean age of 50.93 ± 11.17 y, 2 female and 13 male patients) with solid-organ transplant were included in the study. Of the 15 study patients, 7 were heart transplant, 6 were kidney transplant, and 2 were liver transplant recipients. Three patients had positive aspergillosis cultures from extrapulmonary specimens (1 brain biopsy and 2 wound swap cultures). Other patients with positive cultures were from bronchoalveolar lavage (6 patients), sputum (4 patients), both bronchoalveolar lavage and sputum (1 patient), and deep tracheal aspiration specimen (1 patient). Aspergillus fumigatus was the most common species. Mean hospitalization duration was 31.53 days (range, 2-135 d). Although all patients had positive culture results, 7 patients (46.7%) had negative galactomannan test results at the time of culture specimen collection. Positive galactomannan test results were statistically higher in 6 heart transplant patients (P = .045). All patients had fever at presentation, and 13 patients had been referred to the pulmonary disease department before positive culture results were obtained. Risk factors for pulmonary aspergillosis and its clinical presentation in solid-organ transplant recipients are still unclear. Although the expected time for aspergillosis infection in solid-organ transplant recipients is 6 months after transplant, clinicians must remember the nonspecific presentation of infections in these patients and be aware of the reliability of diagnostic tools.

Invasive Candidiasis in Various Patient Populations: Incorporating Non-Culture Diagnostic Tests into Rational Management Strategies.

Mortality rates due to invasive candidiasis remain unacceptably high, in part because the poor sensitivity and slow turn-around time of cultures delay the initiation of antifungal treatment. β-d-glucan (Fungitell) and polymerase chain reaction (PCR)-based (T2Candida) assays are FDA-approved adjuncts to cultures for diagnosing invasive candidiasis, but their clinical roles are unclear. We propose a Bayesian framework for interpreting non-culture test results and developing rational patient management strategies, which considers test performance and types of invasive candidiasis that are most common in various patient populations. β-d-glucan sensitivity/specificity for candidemia and intra-abdominal candidiasis is ~80%/80% and ~60%/75%, respectively. In settings with 1%–10% likelihood of candidemia, anticipated β-d-glucan positive and negative predictive values are ~4%–31% and ≥97%, respectively. Corresponding values in settings with 3%–30% likelihood of intra-abdominal candidiasis are ~7%–51% and ~78%–98%. β-d-glucan is predicted to be useful in guiding antifungal treatment for wide ranges of populations at-risk for candidemia (incidence ~5%–40%) or intra-abdominal candidiasis (~7%–20%). Validated PCR-based assays should broaden windows to include populations at lower-risk for candidemia (incidence ≥~2%) and higher-risk for intra-abdominal candidiasis (up to ~40%). In the management of individual patients, non-culture tests may also have value outside of these windows. The proposals we put forth are not definitive treatment guidelines, but rather represent starting points for clinical trial design and debate by the infectious diseases community. The principles presented here will be applicable to other assays as they enter the clinic, and to existing assays as more data become available from different populations.

Prevalence of Ocular Chlamydial Infections in South Florida

Ocular chlamydia in the US is a sexually transmitted disease. The true public health burden is unknown. We used a combination of culture and culture independent tests to document disease prevalence over a 28-year (1986–2014) period.Methods:Laboratory records of patient’s samples (n=3,112) submitted to rule out chlamydia were reviewed. Data were extracted for patient’s demographics (age, sex), age and positivity rates for historical methods (1986–2004), direct fluorescent antibody (DFA; n=1,774), culture (n=1,619), nucleic acid amplification tests (NAAT; n=274) and enzyme immunoassay tests (EIA; n=609) from historical data (1986–2014) versus the most recent 10 years, (DFA: n=845) and culture (n=523) (2005–2014). A multiplex polymerase chain reaction assay was used to determine species diversity among 128 random samples (1994–2014). Results: Chlamydial positivity rates ranged from 6.0% to 13.4%, with an average of 10.2%. The highest rates were documented for neonates (33.5%) and the age group 15–29 (14.6%, 24.5%). Culture positivity was highest for nonculture tests (historical): NAAT (43.4%), EIA (23.5%), DFA (13.4%) followed culture (8.5%) and current DFA 7.6% versus 3% for culture. Mixed chlamydial infections were observed in 3.1% of samples. A high prevalence and diversity of ocular chlamydia were evident in patients presenting with ocular surface infections in South Florida.

Comparison of Direct Immunofluorescence and Giemsa Staining in Chlamydia trachomatis Follicular Conjunctivitis

Background: Chlamydia trachomatis is the most common sexually transmitted bacterial infection and can cause various types of human eye disease. There are two general methods for diagnosis of chlamydial infection; cell culture and non-culture tests. Objectives: In this study we evaluated the prevalence of C. trachomatis in follicular conjunctivitis and compared the two rapid direct methods [direct immunofluorescence (DIF) and Giemsa staining] used in diagnosis of chlamydial conjunctivitis. Patients and Methods: In this descriptive and comparative study, 285 patients with follicular conjunctivitis were recruited and admitted to the referral laboratory unit of Farabi Eye Hospital of Tehran and 570 conjunctival scrapings from their right and left eyes were collected and subsequently stained via DIF and Giemsa staining. Results: In this study, 109 (50 males and 59 females) patients (38.24%) had positive results with DIF technique and most of these patients aged 21 - 30 and 11 - 20 years respectively. A number of 47 patients (27 males and 20 females) (16.49%) had positive results with Giemsa staining and in compared to DIF, sensitivity and specificity of Giemsa method was 38.53% and 97.16% respectively. Conclusions: Compared with Giemsa staining, DIF is a suitable test with high sensitivity and specificity and the choice test for rapid diagnosis of chlamydial conjunctivitis for routine purposes.

The microbiological diagnosis of tuberculous meningitis of Haydarpasa-1 study

We aimed to provide data on the diagnosis of tuberculous meningitis (TBM) in this largest case series ever reported. The Haydarpasa-1 study involved patients with microbiologically confirmed TBM in Albania, Croatia, Denmark, Egypt, France, Hungary, Iraq, Italy, Macedonia, Romania, Serbia, Slovenia, Syria and Turkey between 2000 and 2012. A positive culture, PCR or Ehrlich-Ziehl-Neelsen staining (EZNs) from the cerebrospinal fluid (CSF) was mandatory for inclusion of meningitis patients. A total of 506 TBM patients were included. The sensitivities of the tests were as follows: interferon-γ release assay (Quantiferon TB gold in tube) 90.2%, automated culture systems (ACS) 81.8%, LÖwenstein Jensen medium (L-J) 72.7%, adenosine deaminase (ADA) 29.9% and EZNs 27.3%. CSF-ACS was superior to CSF L-J culture and CSF-PCR (p <0.05 for both). Accordingly, CSF L-J culture was superior to CSF-PCR (p <0.05). Combination of L-J and ACS was superior to using these tests alone (p <0.05). There were poor and inverse agreements between EZNs and L-J culture (Κ = −0.189); ACS and L-J culture (Κ = −0.172) (p <0.05 for both). Fair and inverse agreement was detected for CSF-ADA and CSF-PCR (Κ = −0.299, p <0.05). Diagnostic accuracy of TBM was increased when both ACS and L-J cultures were used together. Non-culture tests contributed to TBM diagnosis to a degree. However, due to the delays in the diagnosis with any of the cultures, combined use of non-culture tests appears to contribute early diagnosis. Hence, the diagnostic approach to TBM should be individualized according to the technical capacities of medical institutions particularly in those with poor resources.