Laboratory approaches to determining blood culture contamination rates: an ASM Laboratory Practices Subcommittee report.

Blood culture contamination (BCC) is the presence of specific commensal and environmental organisms cultivated from a single blood culture set out of a blood culture series and that do not represent true bacteremia. BCC can impact quality of care and lead to negative outcomes, unnecessary antibiotic exposure, prolonged hospital stays, and substantial costs. As part of the laboratory's quality management plan, microbiology laboratory personnel are tasked with monitoring BCC rates, preparing BCC rate reports, and providing feedback to the appropriate committees within their healthcare system. The BCC rate is calculated by the laboratory using pre-set criteria. However, pre-set criteria are not universally defined and depend on the individual institution's patient population and practices. This mini-review provides practical recommendations on elaborating BCC rate reports, the parameters to define for the pre-set criteria, how to collect and interpret the data, and additional analysis to include in a BCC report.

High Number of Positive Rapid Plasma Reagin With Low Titers Using the Automated AIX 1000 RPR System.

ABSTRACT: This study evaluated the performance of manual rapid plasma reagin (RPR) and automated AIX1000 RPR tests for the diagnosis of syphilis. Manual RPR showed a 3% reactive result compared with 5.8% for the automated test mainly because of RPR reactive results with low titers not confirmed by Treponema pallidum particle agglutination.

Implementation and Evaluation of Gradient Strip Antimicrobial Susceptibility Testing in US Public Health Laboratories to Respond to Resistant Gonorrhea.

BACKGROUND: Gradient strip antimicrobial susceptibility testing using Etest is conducted by local public health jurisdictions participating in the Strengthening the US Response to Resistant Gonorrhea (SURRG) program to inform public health responses to resistant gonorrhea. Proficiency testing results across the participating laboratories were analyzed and a comparison of Etest with the agar dilution method was conducted. METHODS: Laboratories participating in SURRG performed Etest for azithromycin (AZM), cefixime (CFX), and ceftriaxone (CRO). Concurrence between minimum inhibitory concentrations (MICs) obtained with Etest versus the agar dilution method using corresponding isolates was defined as ±1 double dilution. Specific levels of reduced susceptibility were termed "alerts" and included isolates with the following MICs: ≥2.0 µg/mL (AZM), ≥0.25 µg/mL (CFX), and ≥0.125 µg/mL (CRO). Categorical (alert/nonalert) agreement was calculated for MICs determined using Etest and agar dilution methods. RESULTS: Strengthening the US Response to Resistant Gonorrhea laboratories had high proficiency testing scores (≥98%) and low levels of interlaboratory variations in MICs. The overall concurrence of MICs (essential agreement) determined using agar dilution, and Etest was 96% (CRO), 96% (CFX), and 95% (AZM). Depending on the antibiotic tested, between 27% and 66% of isolates with alert MICs determined by Etest also had alert MICs using the reference agar dilution methodology; however, most of these alert MICs were detected at threshold levels. CONCLUSIONS: This study demonstrates that MICs produced by SURRG laboratories using Etest have a high level of concurrence with agar dilution. Although confirmation of specific alert MICs varied, Etest facilities rapid detection and response to emerging resistant gonorrhea.

A case report of Nocardia spp. infective endocarditis in an injection drug user.

BACKGROUND: Nocardia-related endocarditis is rare. Intravenous drug use with nonsterile injection practices is a potential risk factor for nocardia infection. Disseminated nocardiosis with endovascular involvement is rarely reported in immunocompetent individuals. CASE PRESENTATION: A 54-year-old male was diagnosed with infective endocarditis due to Nocardia asteroides with septic emboli in the brain and spleen. The use of a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) rapid diagnostic system was beneficial in identifying the causative organism. He was empirically treated with combination therapy consisting of three antibiotics. Antimicrobial susceptibility testing indicated that all three antibiotics had favorable minimum inhibitory concentrations (MICs). Due to his clinical status, he was not a surgical candidate. Patient passed away after discharge to hospice. CONCLUSIONS: This case demonstrates unique challenges in the identification, diagnosis, and management of Nocardia-related infective endocarditis. A detailed history of injection practices should guide clinicians in assessing the risk for environmental pathogens. Valvular surgery and combination antibiotic therapy should be recommended for all eligible patients to improve the chances of survival.

Cutaneous infection caused by paraconiothyrium cyclothyrioides in a renal transplant recipient.

Infections because of Coelomycetes are being diagnosed more frequently, ranging from superficial cutaneous to disseminated infections. An increasing incidence of infections because of emerging environmental fungi are being reported in immunocompromised patients because of exposure to soil, plants, and water. We report a case of cutaneous infection because of Paraconiothyrium cyclothyrioides, a Coelomycetous fungi, including literature review on reported cases and discuss suggested treatment options.

First Case of High-Level Azithromycin-Resistant Neisseria gonorrhoeae in North Carolina.

We report on the first high-level azithromycin-resistant Neisseria gonorrhoeae isolate (minimum inhibitory concentration, ≥256 µg/mL) in North Carolina isolated from a pharyngeal swab of a 33-year-old HIV-negative man who has sex with men. In addition, the isolate was found to be susceptible to cefixime, ceftriaxone, and penicillin and resistant to tetracycline. By whole-genome sequencing, the strain was assigned as MLST ST9363, NG-MAST ST5035, and a novel NG-STAR sequence type, ST1993.

Neisseria gonorrhoeae Septic Arthritis With Contiguous Infection Consistent With Acute Osteomyelitis.

Neisseria gonorrhoeae osteomyelitis is a rare complication of disseminated gonococcal infection. As the rates of N. gonorrhoeae continue to increase in the United States, clinicians may encounter patients with disseminated gonococcal infection complicated by gonococcal osteomyelitis. Screening and appropriate treatment of N. gonorrhoeae remains paramount, especially with growing antibiotic resistance.

False daptomycin-nonsusceptible MIC results by Microscan panel PC 29 relative to Etest results for Staphylococcus aureus and enterococci.

This study correlated the daptomycin MIC results obtained by Microscan and by Etest in Staphylococcus aureus and enterococci and found that the Microscan panel GP 29 had a high rate of false nonsusceptible results. Of the isolates interpreted as nonsusceptible by Microscan, 87% of Staphylococcus aureus, 90% of Enterococcus faecalis, and 88% of Enterococcus faecium isolates were interpreted as susceptible by Etest. In turn, Etest also has false nonsusceptible results compared to reference methods.

Four-year experience with simultaneous culture and Shiga toxin testing for detection of Shiga toxin-producing Escherichia coli in stool samples.

We report our experience with universal Shiga toxin-producing Escherichia coli (STEC) screening using culture and Shiga toxin antigen testing over 4 years. Twelve cases were detected-8 detected by both culture and Shiga toxin immunochromatographic assay (IA), 3 by culture, and 1 by IA only. The addition of Shiga toxin testing is of questionable benefit over culture alone for detection of STEC in areas of low prevalence.

Analytical evaluation of the cobas® 6800 system for the detection and quantification of BK Virus (BKV) and Epstein Barr Virus (EBV) at a US solid organ and hematopoietic stem cell transplant center.

The cobas® EBV and BKV assays are the first FDA-approved, quantitative assays for monitoring posttransplant reactivation of these viruses. In this study, we assessed performance of the fully-automated cobas® assays, compared with Diasorin Molecular ASR, our laboratory developed test, and demonstrated a strong interassay correlation for BK and EBV monitoring.

In Vitro Activity of Omadacycline and Comparator Antibiotics against Extended-Spectrum Beta-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Urinary Isolates.

Limited oral antibiotic options exist for urinary tract infections (UTI) caused by ESBL-producing Enterobacterales. The aim of the study was to evaluate in vitro activity of omadacycline and comparator antibiotics against clinical ESBL-producing and non-ESBL-producing E. coli and K. pneumoniae urinary isolates. 102 isolates each of E. coli and K. pneumoniae were collected from clinical urine specimens in 2019. By design, an equal number of each species were included that tested positive and negative for ESBL production. Omadacycline MICs were determined using gradient test strips and compared to MICs of comparator antibiotics as determined by an automated broth microdilution system. Isolates were considered susceptible to omadacycline if the MIC was ≤4 µg/mL for each species. 54.9% of all ESBL-producing isolates were susceptible to omadacycline, but better susceptibility was observed for ESBL-producing E. coli (74.5%). Omadacycline MICs were 2-4 fold lower for E. coli and K. pneumoniae strains not producing ESBL. The omadacycline MIC 50 and 90 values were 4 and 16 µg/mL, respectively, for all isolates studied. 74.5% of all isolates were considered susceptible to omadacycline. MICs were generally lower for E. coli strains with MIC 50 and 90 values of 4 and 8 µg/mL, respectively (87.3% susceptible), compared with K. pneumoniae. Overall, the most active agents were omadacycline and nitrofurantoin, while other comparator antibiotics were less active. Omadacycline represents a promising oral antibiotic for treating UTI caused by ESBL-producing E. coli, particularly when resistance limits other oral options. Prospective, controlled clinical trials are needed to validate these in vitro results.

Clinical impact of a multiplex rapid diagnostic pneumonia panel in critically ill patients.

Objective: To evaluate the clinical impact of the BioFire FilmArray Pneumonia Panel (PNA panel) in critically ill patients. Design: Single-center, preintervention and postintervention retrospective cohort study. Setting: Tertiary-care academic medical center. Patients: Adult ICU patients. Methods: Patients with quantitative bacterial cultures obtained by bronchoalveolar lavage or tracheal aspirate either before (January-March 2021, preintervention period) or after (January-March 2022, postintervention period) implementation of the PNA panel were randomly screened until 25 patients per study month (75 in each cohort) who met the study criteria were included. Antibiotic use from the day of culture collection through day 5 was compared. Results: The primary outcome of median time to first antibiotic change based on microbiologic data was 50 hours before the intervention versus 21 hours after the intervention (P = .0006). Also, 56 postintervention regimens (75%) were eligible for change based on PNA panel results; actual change occurred in 30 regimens (54%). Median antibiotic days of therapy (DOTs) were 8 before the intervention versus 6 after the intervention (P = .07). For the patients with antibiotic changes made based on PNA panel results, the median time to first antibiotic change was 10 hours. For patients who were initially on inadequate therapy, time to adequate therapy was 67 hours before the intervention versus 37 hours after the intervention (P = .27). Conclusions: The PNA panel was associated with decreased time to first antibiotic change and fewer antibiotic DOTs. Its impact may have been larger if a higher percentage of potential antibiotic changes had been implemented. The PNA panel is a promising tool to enhance antibiotic stewardship.

Impact of the AACC Global Laboratory Quality Initiative in Partnership with Professional Societies and Universities in Latin America and the Caribbean.

The Global Lab Quality Initiative (GLQI), formerly known as the Emerging Countries program, was funded through a generous endowment from the Wallace H. Coulter Foundation. The aims of GLQI are to develop and implement innovative programs to promote education and training in laboratory medicine for low- or lower middle-income countries worldwide. From its inception in 2010, the GLQI was focused solely on the Latin America and Caribbean (LAC) region under the purview of AACC's Latin American Working Group (LAWG), the members of which have strong ties to the region thereby facilitating the partnerships with national societies. The LAWG has provided in-person workshops in the LAC countries, at the AACC Annual Scientific Meeting, and on-demand webinars. The LAWG aims to implement the GLQI aims in the LAC region. In-person workshops are based on best-practice recommendations and sources such as Clinical Laboratory Standard Institute guidelines and supplemented with professional experiences of the LAWG's lecturers and local experts of the countries visited. In 2015, the GLQI expanded to other regions of the world. Here we report the experience of the LAWG workshops, results of participant surveys, in-person visits to laboratories post-workshop, and the lessons learned throughout the years across different geographic areas. We are hopeful this report provides insights into the challenges and successes of the LAWG in LAC to help support the expansion of the GLQI.

Screening for Bacteremia in Trauma Patients: Traditional Markers Fall Short.

BACKGROUND: Deranged physiology in trauma complicates the clinical identification of sepsis, resulting in overscreening for bacteremia. No clinical signs or biomarkers accurately diagnose sepsis in this population. Our objective was to evaluate the accuracy of the current criteria used to prompt screening for bacteremia in trauma patients and determine independent predictors of bacteremia. MATERIALS AND METHODS: Adult trauma patients admitted to our level I academic trauma center who had blood cultures (BCs) drawn were identified. Those with positive BCs were compared to those with negative or false positive BCs. False positive was defined as a BC deemed contaminated and not treated at the discretion of the attending physician. RESULTS: Over a 2-year period, 366 trauma patients had BCs drawn. After excluding surveillance cultures (those drawn to demonstrate bacteremia clearance), 492 unique BC sets were evaluated; 104 (21.1%) BC sets were positive; 30 (28.8%) of these were falsely positive, resulting in a true-positive rate of 15% in the screened population. Univariate analysis suggested temperature and heart rate were associated with positive BC, while multivariable analysis found only the presence of a central line and lactic acid to be predictive. Procalcitonin (PCT) was poorly predictive, with a positive predictive value of 18% and a negative predictive value of 91%. CONCLUSION: Current tools for identifying bacteremia in trauma patients result in overscreening. PCT may have a limited role as a negative predictor for bacteremia. Given that false-positive BCs have negative patient and economic consequences, future study should focus on development of alternative screening modalities.

Fatal Mycobacterium abscessus endocarditis misidentified as Corynebacterium spp.

The microbiological similarities of rapidly growing mycobacteria and corynebacteria impose potential for misidentification in the laboratory. This report describes a fatal case of infectious endocarditis caused by Mycobacterium abscessus, initially identified and treated as Corynebacterium spp. Acid-fast staining should be performed routinely when multiple blood cultures grow Corynebacterium spp.

Bacterial contamination of platelets.

Bacterial contamination of platelet products, both single donor apheresis platelet units and whole blood-derived platelet pools, continues to occur despite preventive measures. While some advances have been made in decreasing the rate of bacterial contamination of platelet units, particularly through diversion methods and early culture, a great deal remains to be done to eliminate the problem. Diversion methods have decreased contamination rates associated with skin commensal organisms. Culture methods are now widely used and many at-issue detection methods have been developed or are undergoing development. This article reviews the current developments and the challenges that remain to minimize and detect bacterial contamination of platelet products.

Clinical, Epidemiologic, and Laboratory Aspects of Methicillin-Resistant Staphylococcus aureus Infections.

Oxacillin-resistant Staphylococcus aureus (abbreviated MRSA for historical reasons) is a major pathogen responsible for both hospital- and community-onset disease. Resistance to oxacillin in most clinical isolates of S. aureus is mediated by PBP2a, a penicillin-binding protein with low affinity to beta-lactams, encoded primarily by the mecA gene. Rapid and accurate methods of susceptibility testing of S. aureus isolates to identify MRSA infections are important tools to limit the spread of this organism. This review focuses on the clinical significance of MRSA infections and new approaches for the laboratory diagnosis and epidemiologic typing of MRSA strains.

Rapid Methods for Detection of MRSA in Clinical Specimens.

Traditional antimicrobial susceptibility test methods for detection of S. aureus resistant to oxacillin (MRSA) such as disk diffusion, broth microdilution, and oxacillin screen plate require 18-24 h of incubation after having the organism growing in pure culture. Rapid and accurate identification of MRSA isolates is essential not only for patient care, but also for effective infection control programs to limit the spread of MRSA. In the last few years, several commercial rapid tests for detection of MRSA directly from nasal and wound swabs, as well as from positive blood cultures, have been developed for use in clinical laboratories. Chromogenic agar plates and real-time PCR and other molecular tests are gaining popularity as MRSA screening tests because they have the advantage of a lower turnaround time than that of traditional culture and susceptibility testing and they are capable of detecting MRSA directly from nasal and wound swabs, allowing rapid identification of colonized or infected patients. In addition, molecular methods able to detect and differentiate S. aureus and MRSA (SA/MRSA) directly from blood cultures are becoming a useful tool for rapid detection of bacteremia caused by MSSA and MRSA. This review focuses on the procedures for performing testing using rapid methods currently available for detection of MRSA directly from clinical specimens.

Collaborative Antimicrobial Stewardship: Working with Microbiology.

There have been tremendous advances in methodologies available for detection and identification of organisms causing infections. Providers can now obtain identification results and antimicrobial susceptibility results in a shorter period of time. However, declining health care resources highlight the importance of selecting the right test at the right time to maximize diagnostic benefits. Therefore, the role of the antimicrobial stewardship team in the clinical microbiology laboratory has expanded to include diagnostic stewardship and provision of guidance on test selection for diagnosis and management of infection. This review focuses on the experience of our group in collaborative stewardship, emphasizing successes and challenges.