A conceptual framework for nomenclatural stability and validity of medically important fungi: a proposed global consensus guideline for fungal name changes supported by ABP, ASM, CLSI, ECMM, ESCMID-EFISG, EUCAST-AFST, FDLC, IDSA, ISHAM, MMSA, and MSGERC

The rapid pace of name changes of medically important fungi is creating challenges for clinical laboratories and clinicians involved in patient care. We describe two sources of name change which have different drivers, at the species versus the genus level. Some suggestions are made here to reduce the number of name changes. We urge taxonomists to provide diagnostic markers of taxonomic novelties. Given the instability of phylogenetic trees due to variable taxon sampling, we advocate to maintain genera at the largest possible size. Reporting of identified species in complexes or series should where possible comprise both the name of the overarching species and that of the molecular sibling, often cryptic species. Because the use of different names for the same species will be unavoidable for many years to come, an open access online database of the names of all medically important fungi, with proper nomenclatural designation and synonymy, is essential. We further recommend that while taxonomic discovery continues, the adaptation of new name changes by clinical laboratories and clinicians be reviewed routinely by a standing committee for validation and stability over time, with reference to an open access database, wherein reasons for changes are listed in a transparent way.

Analysis of infections among patients with historical culture positive for extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli or Klebsiella pneumoniae: Is ESBL-targeted therapy always needed?

Objective

Among patients with a history of ESBL infection, uncertainty remains regarding whether all of these patients require ESBL-targeted therapy when presenting with a subsequent infection. We sought to determine the risks associated with a subsequent ESBL infection to help inform empiric antibiotic decisions.

Methods

A retrospective cohort study of adult patients with positive index culture for Escherichia coli or Klebsiella pneumoniae (EC/KP) receiving medical care during 2017 was conducted. Risk assessments were performed to identify factors associated with subsequent infection caused by ESBL-producing EC/KP.

Results

In total, 200 patients were included in the cohort, 100 with ESBL-producing EC/KP and 100 with ESBL-negative EC/KP. Of 100 patients (50%) who developed a subsequent infection, 22 infections were ESBL-producing EC/KP, 43 were other bacteria, and 35 had no or negative cultures. Subsequent infection caused by ESBL-producing EC/KP only occurred when the index culture was also ESBL-producing (22 vs 0). Among those with ESBL-producing index culture, the incidences of subsequent infection caused by ESBL-producing EC/KP versus other bacterial subsequent infection were similar (22 vs 18; P = .428). Factors associated with subsequent infection caused by ESBL-producing EC/KP include history of ESBL-producing index culture, time ≤180 days between index culture and subsequent infection, male sex, and Charlson comorbidity index score >3.

Conclusions

History of ESBL-producing EC/KP culture is associated with subsequent infection caused by ESBL-producing EC/KP, particularly within 180 days after the historical culture. Among patients presenting with infection and a history of ESBL-producing EC/KP, other factors should be considered in making empiric antibiotic decisions, and ESBL-targeted therapy may not always be warranted.

Rare, Atypical Mycobacterium Infection of the Hand in Immunocompetent Individuals

We present two cases of immunocompetent individuals diagnosed with nontuberculous infections of the hand caused by organisms rarely seen in the clinical setting: Mycobacterium heckeshornense and Mycobacterium chelonae. In the first case, a 50-year-old male presented with tenosynovitis of left long finger. He was subsequently found to have a Mycobacterium heckeshornense infection that was resolved with multiple surgeries and a long-term regimen of several antibiotics. The second case was a 29-year-old female with a history of a trivial hand injury infected with Mycobacterium chelonae. She was successfully treated with surgical debridement and antibiotics over the course of eight months. It is important to recognize the increasing prevalence of these two species of bacteria as human pathogens that can result in infections of the extremities even in immunocompetent individuals. (Journal of Surgical Orthopaedic Advances 32(1):055-058, 2023).

877. Synovial Fluid Testing Using the BioFire® Joint Infection (JI) Panel Potentially Decreases Time to Antibiotic Optimization for Acute Joint Infections

Background

Traditional synovial fluid culture for acute joint infection (AJI) is time-consuming, potentially delaying initiation of targeted antimicrobial therapy. The BioFire® Joint Infection (JI) panel, a multiplex PCR for synovial fluid, has been shown to have 90.2% sensitivity and 99.8% specificity for diagnosis of AJI. We sought to determine the potential impact of the JI panel on antimicrobial use for AJI at our institution.

Methods

Antimicrobial use was retrospectively reviewed in a cohort of adult inpatients who underwent synovial fluid culture and were diagnosed with septic arthritis or periprosthetic joint infection from Sept 2021-Apr 2022. Patients were excluded if there was an alternative source of infection or septic shock. Synovial fluid specimens were tested using the JI panel, and results were compared to those of traditional culture methods. Patients who were initially treated with broad-spectrum antimicrobials for AJI were included in a review of antimicrobial prescribing. Records were reviewed to determine the time at which a transition to targeted therapy was made when using culture. This was compared to the time at which panel results could be available and acted upon, in this study presumed to be 12 hours after culture collection.

Results

42 inpatients met study criteria for comparison of culture and JI panel results. The panel identified the organism that was grown in culture in 21 cases while detecting an organism in 5/16 culture-negative cases (table 1). In 5 cases, culture identified an organism not included on the JI panel. 29 patients met criteria for review of antimicrobial prescribing. Of these, therapy in 14/16 with positive cultures could have been changed earlier (table 2), resulting in an average reduction of time to targeted therapy of 57 hours (range 27–107 h, median 50.5 h) per patient. Targeted therapy could have occurred in 5/13 culture-negative cases.

Summary of comparison of culture and BJI panel results.

*Organisms identified by culture: Coagulase-negative staphylococci (n=4), Pasteurella multocida (n=1)

**Organisms detected by JI panel: Streptococcus pyogenes (n=2), Streptococcus agalactiae (n=1), Finegoldia magna (n=1), Enterobacter cloacae (n=1)

Proportion of patients eligible for a change in antimicrobial therapy.

Conclusion

Use of the JI panel could have prompted earlier optimized therapy in approximately two-thirds of patients. In 5 instances where cultures were negative, important AJI pathogens were identified. Another potential benefit includes reduced exposure to unnecessary broad-spectrum antimicrobials. Future study should evaluate the actual impact of the JI panel in practice.

Disclosures

All Authors: No reported disclosures.

184. Impact of the BioFire® FilmArray® Blood Culture Identification 2 Panel on Antimicrobial Treatment of Enterobacterales Blood Stream Infections

Background

The BioFire® FilmArray® Blood Culture Identification 2 (BCID2) panel is a rapid diagnostic tool that uses multiplex polymerase chain reaction technology to identify 43 different genetic targets. BCID2 detects 13 additional targets, including 7 resistance markers, not detected by the original BCID panel. For this reason, our institution changed panels from BCID to BCID2 in August 2020. The purpose of this study was to assess the time to antibiotic change for Enterobacterales bloodstream infections before and after switch to BCID2.

Methods

This was a retrospective, observational, before-and-after study conducted at an 885-bed academic medical center. Adult patients with blood cultures positive for E. coli or K. pneumoniae (EC/KP) who received broad spectrum beta-lactam therapy were included. Patients with a polymicrobial or concurrent infection, hemodynamic instability, lack of source control by day 5, or death within 72 hours (hrs) of cultures being collected were excluded. The primary outcome was time to antibiotic change in the BCID group compared to the BCID2 group. Secondary outcomes included time to de-escalation or escalation and the number of opportunities for de-escalation or escalation.

Results

88 patients were included, 55 in the BCID-group and 33 in the BCID2-group. Baseline characteristics are reported in Table 1. Median time to first antibiotic change was 65.3 hrs in the BCID-group vs 69.6 hrs in the BCID2-group (p=0.53). Times to first de-escalation and escalation and number of opportunities for de-escalation and escalation are presented in Table 2. Proportion of missed de-escalation opportunities based on panel results was greater in the BCID2 group (63.6% vs 0%, p< 0.05).

Conclusion

Opportunities to make timely antibiotic modifications with the use of the BCID2 panel exist for EC/KP blood stream infections. While no difference in time to first antibiotic change was present between groups, this highlights the importance of having an active stewardship team member available to respond to rapid diagnostic test results.

Disclosures

All Authors: No reported disclosures.

333. Clinical Impact of a Multiplex Rapid Diagnostic Panel in Critically Ill Patients

Background

The BioFire FilmArray® Pneumonia Panel® (PP) is a rapid diagnostic test that detects select bacterial and viral respiratory pathogens and the presence of certain antimicrobial resistance genes within 75 min of testing. Starting Nov 2021 respiratory specimens from all adult ICU patients (pts) with quantitative cultures (cx) obtained by bronchoalveolar lavage (BAL) or tracheal aspirate (TA) were automatically tested with PP. The purpose of this study was to evaluate the clinical impact of the PP.

Methods

This single-center, retrospective cohort study compared patients prior to (PRE) (Jan - Mar 2021) and after (POST) (Jan - Mar 2022) implementation of the PP. Adult ICU pts with a quantitative cx obtained by BAL or TA during the study periods were reviewed in random order until 25 pts from each study month meeting study criteria were identified (75 pts in each cohort). Pts with another infection other than bacteremia with the same causative pathogen requiring antibiotics (ABX) in the previous 14 days through 5 days after specimen collection or pts who died within 5 days after specimen collection were excluded. ABX therapy for the 5 days after cx collection was evaluated. The primary outcome was time to first ABX change based on microbiologic test results. Secondary outcomes included ABX days of therapy (DOTs), time to adequate therapy, and potential vs actual ABX changes made based on the PP in POST cohort.

Results

PRE pts were a median of 54 yrs old and 56% female compared to 59 yrs and 32% female in POST cohort. Median time to first ABX change based on microbiologic data was 50.3 hrs PRE vs 21.2 hrs POST (p=0.0006). 56 (75%) of POST ABX regimens were eligible for change based on PP results; actual change occurred in 30 (54%) of these regimens (ABX de-escalation in 23 and escalation in 7). Median ABX DOTs were 8 PRE vs 6 POST (p = 0.07). For the pts with ABX changes made based on PP results, median time to first ABX change was 10 hrs. For pts who were initially on inadequate therapy, time to adequate therapy was 67 hrs PRE vs 37 hrs POST.

Conclusion

The PP was associated with decreased time to first ABX change and fewer ABX DOTs. The PP may have had a larger impact if a higher percentage of potential ABX changes were implemented. The PP may be a useful ABX stewardship tool.

Disclosures

All Authors: No reported disclosures.

Treatment of Candida nivariensis Blood Stream Infection With Oral Isavuconazole

Candida nivariensis is a rarely isolated yeast that is now considered a species within the Candida glabrata complex. Anti-fungal susceptibilities and treatments of Candida nivariensis are often assessed on a case-by-case basis. In this case, a 70-year-old male with a complex medical history presented to a large academic medical center in the United States for vascular surgery. After surgery, the patient's white blood cell count increased prompting an infectious workup. The patient was found to have a Candida nivariensis bloodstream infection of unknown origin. Given the patient's clinical stability and QTc prolongation, he was treated with a 14-day course of oral isavuconazole. The patient experienced resolution of symptoms and clearance of subsequent blood cultures. At the time of writing this case report (11 months later), he has had no relapse of his fungal infection. Based on a search of the medical literature, this appears to be the first published case of Candida nivariensis fungemia successfully treated with oral isavuconazole.

A comparison of active versus passive methods of responding to rapid diagnostic blood culture results

OBJECTIVE

To compare 2 methods of communicating polymerase chain reaction (PCR) blood-culture results: active approach utilizing on-call personnel versus passive approach utilizing notifications in the electronic health record (EHR).

DESIGN

Retrospective observational study.

SETTING

A tertiary-care academic medical center.

PATIENTS

Adult patients hospitalized with ≥1 positive blood culture containing a gram-positive organism identified by PCR between October 2014 and January 2018.

METHODS

The standard protocol for reporting PCR results at baseline included a laboratory technician calling the patient's nurse, who would report the critical result to the medical provider. The active intervention group consisted of an on-call pager system utilizing trained pharmacy residents, whereas the passive intervention group combined standard protocol with real-time in-basket notifications to pharmacists in the EHR.

RESULTS

Of 209 patients, 105, 61, and 43 patients were in the control, active, and passive groups, respectively. Median time to optimal therapy was shorter in the active group compared to the passive group and control (23.4 hours vs 42.2 hours vs 45.9 hours, respectively; P = .028). De-escalation occurred 12 hours sooner in the active group. In the contaminant group, empiric antibiotics were discontinued faster in the active group (0 hours) than in the control group and the passive group (17.7 vs 7.2 hours; P = .007). Time to active therapy and days of therapy were similar.

CONCLUSIONS

A passive, electronic method of reporting PCR results to pharmacists was not as effective in optimizing stewardship metrics as an active, real-time method utilizing pharmacy residents. Further studies are needed to determine the optimal method of communicating time-sensitive information.

Evaluation of the Potential Impact of a Multiplex Rapid Diagnostic Panel in Critically Ill Patients With Hospital-Acquired Pneumonia

Background Rapid diagnostic tools have emerged as valuable assets assisting clinicians in decision-making regarding patient management in the hospital setting. Our study sought to identify the potential impact of the BioFire® FilmArray® Pneumonia Panel (FP Panel) (BioFire Diagnostics, Salt Lake City, UT, USA) in patients with hospital-acquired pneumonia (HAP). Methods Respiratory samples obtained by bronchoalveolar lavage (BAL) or tracheal aspiration (TA) from ICU patients with a diagnosis of HAP were tested by the FP panel in addition to routine bacterial cultures. In addition, the electronic health records of these patients were reviewed to determine what potential changes in antimicrobial therapy could have been implemented if the panel results were known to the treatment team in real-time. A cost analysis was also performed incorporating the cost of the pneumonia panel and the savings associated with the potential decrease of antibiotic use and avoidance of the rapid viral diagnostic panel.  Results Fifty-six patients met the study criteria. The FP panel results could have prompted a change in therapy in 36 (64.3%) patients, with an anticipated mean reduction in time to optimized therapy of approximately 51 hours. In addition, the panel identified three cases where antimicrobials should have been altered because patients were not receiving empiric therapy with activity against the causative pathogen and 34 opportunities for antibiotic de-escalation. The cost analysis calculated an additional cost of $10 per patient associated with using the FP panel.  Conclusions The FP panel could have prompted a change in therapy in about two-thirds of patients studied. Its potential benefits include a more rapid time to optimized therapy, reduced exposure to and cost of broad-spectrum antimicrobials, and reduced cost of other rapid diagnostic tests.

1032. Evaluation of a Multiplex Rapid Diagnostic Panel in Respiratory Specimens from Critically Ill Patients with Hospital-Acquired Pneumonia

Background

Rapid diagnostic tests can be a valuable aide in clinical decision-making but often cost more than traditional cultures. Prior to its implementation at our institution, we sought to evaluate the potential clinical and financial impact of using the FilmArray® Pneumonia Panel® (FP panel) in patients with hospital-acquired pneumonia (HAP).

Methods

This was a retrospective, observational, comparative study conducted at an 885-bed academic medical center. Respiratory samples obtained by bronchoalveolar lavage or tracheal aspiration from adult intensive care unit (ICU) patients with a diagnosis of HAP from Nov 2019 – Feb 2020 were tested by the FP panel in addition to routine cultures. Medical records were reviewed to determine potential changes in antimicrobial therapy if FP panel results were known by the treatment team in real time. A cost analysis was also performed incorporating the cost of the FP panel and the savings associated with the potential avoidance of antibiotics and other rapid diagnostic tests normalized per patient.

Results

56 patients met study criteria. FP panel results could have prompted a change in therapy in 36 (64.3%) patients, with a mean reduction in time to optimized therapy of approximately 51 hours. The panel identified 3 cases where the causative pathogen was not treated by empiric therapy and 34 opportunities for antibiotic de-escalation, the most common being the discontinuation of empiric vancomycin. 36 patients had been tested with a Respiratory Virus Panel, which could have been avoided if the FP panel was used. The potential therapy impact based on specific ICU and respiratory culture results is summarized in Table 1. The cost analysis calculated an additional cost of &10 per patient associated with using the FP panel.

Table 1. Potential Changes in Therapy Based on Patient Location and Culture Result

Conclusion

The FP panel could have prompted a change in therapy in about two-thirds of patients studied. Its potential benefits include quicker time to optimized therapy, reduced exposure to and cost of broad-spectrum antimicrobials, and reduced cost of other rapid diagnostic tests.

Disclosures

James Johnson, PharmD, FLGT (Shareholder) Vera Luther, MD, Nothing to disclose

A two-transcript biomarker of host classifier genes for discrimination of bacterial from viral infection in acute febrile illness: a multicentre discovery and validation study

BACKGROUND

Acute febrile illness is one of the main reasons for outpatient hospital visits worldwide. However, differential diagnosis between bacterial and viral causes is challenging and misdiagnosis can result in antimicrobial overuse and hinder prompt treatment. We aimed to build and validate a diagnostic model to discriminate bacterial from viral infection in acute febrile illness by evaluating the expression of potential classifier host genes.

METHODS

In this multicentre discovery and validation study, we included patients aged 14-85 years with acute febrile illness (fever for ≤14 days, axillary temperature of ≥38°C, and confirmed bacterial infection, viral infection, or non-infectious inflammatory disease), and healthy control participants (no significant medical history and no fever within the past 90 days) from four hospitals in Shandong province, China. Patients from the first hospital were divided into the screening, discovery, and internal validation groups, and patients from the three other hospitals comprised the external validation group. We measured expression of candidate genes in peripheral blood by RT-PCR, and patients for whom a successful RT-PCT result was recorded were included in the next-step analysis. For patients from the first hospital, those enrolled during the early phase of the study were assigned to the screening group, which was used to identify the optimal transcripts (IFI44L and PI3) for discrimination between bacterial and viral infections by screening four candidate genes (FAM89A, IFI44L, PI3, and ITGB2) by RT-PCR. The remaining patients were then randomly assigned (1:1) to discovery and internal validation groups by time of admission and blood drawing via the equidistant random sampling method. A logistic regression model integrating the mRNA levels of IFI44L and PI3 was built by use of the discovery group, and the diagnostic performance of the model was evaluated in the internal and external validation groups using area under the receiver operating curve (AUC), sensitivity, and specificity.

FINDINGS

Between March 1, 2018, and Aug 31, 2019, we assessed 1658 individuals for inclusion in the study. After exclusion of ineligible participants, 458 participants were enrolled (178 patients with acute febrile illness caused by bacterial infection, 212 with acute febrile illness caused by viral infection, 38 with non-infectious inflammatory diseases, and 30 healthy controls). The 390 patients with bacterial or viral infections were assigned to one of four groups: screening (n=64, 33 with bacterial infections and 31 with viral infections), discovery (n=124, 55 with bacterial infections and 69 with viral infections), internal validation (n=124, 55 with bacterial infections and 69 with viral infections), and external validation (n=78, 35 with bacterial infections and 43 with viral infections). Of the four candidate host genes (FAM89A, IFI44L, PI3, and ITGB2), IFI44L and PI3 showed the most discriminative expression pattern and were used to build the logistic regression model. We established the optimal cutoff of the bacterial infection likelihood score to be 0·547598. With the diagnostic result from the gold standard tests (culture and PCR) as the reference, the two-transcript classifier model had an AUC of 0·969 (95% CI 0·937-1·000), sensitivity of 0·891 (0·782-0·949), and specificity of 0·971 (0·900-0·992) to discriminate bacterial and viral infections in the internal validation group. The model showed similar results in the external validation group (AUC 0·986, 95% CI 0·968-1·000; sensitivity 0·857, 0·706-0·937; and specificity 0·954, 0·845-0·987).

INTERPRETATION

IFI44L and PI3 transcripts, measured by RT-PCR, are robust classifiers to discriminate bacterial from viral infection in acute febrile illness. This two-transcript biomarker has the potential to be transformed into a commercial panel and applied universally.

FUNDING

None.

1267. Comparative activity of omadacycline against extended-spectrum beta-lactamase positive and negative Escherichia coli and Klebsiella pneumoniae strains recovered from urine specimens

Background

Omadacycline (OMC) is a novel tetracycline (TET) derivative antibiotic with activity against TET-resistant Enterobacterales. OMC is available in both oral and intravenous formulations and is has been studied as a treatment of uncomplicated urinary tract infection (UTI) and acute pyelonephritis. The purpose of this study was to evaluate OMC activity against extended-spectrum beta-lactamase (ESBL) positive and negative Enterobacterales strains recovered from urine specimens.

Methods

Urine samples from patients with suspected UTI were quantitatively plated onto blood agar and MacConkey agar plates in the microbiology lab of Wake Forest Baptist Medical Center. After overnight incubation, colonies were identified to the species level by MALDI-TOF system. Susceptibility testing was performed for isolates of E. coli and K. pneumoniae. OMC and TET susceptibility testing was performed by disk diffusion and gradient strip methodologies. Results were interpreted in accordance with the Clinical and Laboratory Standards Institute (CLSI) or Food and Drug Administration breakpoints. Isolates were tested in triplicate. ESBL screening and susceptibility testing to oral antibiotics commonly prescribed for UTI were performed by the MicroScan WalkAway System. Susceptibility rates and MIC₅₀/₉₀ were calculated and subsets of isolates were analyzed using descriptive statistics.

Results

A total of 204 isolates, including 102 E. coli and 102 K. pneumoniae, were tested. All but 1 isolate (99.5%) exhibited categorical agreement in results generated by the strip (Table 1) and disk (data not shown) methods and this was considered a minor error involving an intermediate result. OMC MIC₉₀ for E. coli and K. pneumoniae were 6 µg/mL and >32 µg/mL, respectively. OMC displayed increased susceptibility rates compared to TET regardless of isolate species or ESBL positivity (Table 2).

Table 1. Omadacycline Minimum Inhibitory Concentrations (MICs, µg/mL)

Table 2. Susceptibilities of Oral Antibiotics Used to Treat UTI (% S)

Conclusion

OMC exhibits promising antimicrobial activity against TET-resistant and ESBL-positive E. coli and K. pneumoniae. OMC displays superior activity to ESBL positive E. coli when compared to ESBL positive K. pneumoniae. These data support the development of OMC as a much needed option in the treatment of UTI caused by resistant Enterobacterales.

Disclosures

Tyler J. Stone, PharmD, Paratek (Research Grant or Support) Abdullah Kilic, MD, Paratek (Grant/Research Support) John Williamson, PharmD, Paratek (Research Grant or Support) Elizabeth Palavecino, MD, Paratek (Grant/Research Support)Paratek (Grant/Research Support)

118. Optimizing the management of coagulase-negative staphylococci (CoNS) contaminants by reporting the species name

Background

CoNS are common isolates in blood cultures (BCx), but many are contaminants contributing to unnecessary antibiotic use. When CoNS are isolated from multiple BCx, different species and/or different susceptibility patterns may suggest contamination. Species reporting of CoNS is not performed at all hospitals. The purpose of this study was to characterize antibiotic use attributable to CoNS positive (pos) BCx and determine if reporting CoNS species could help reduce unnecessary antibiotics.

Methods

A retrospective chart review was conducted of inpatients at an academic medical center before (Jan-June 2017) and after (Sept 2019-Feb 2020) implementation of CoNS species reporting. CoNS species were hidden to providers in the before group. Patients (pts) ≥18 years old with ≥1 BCx pos for CoNS were included. Pts who were neutropenic, treated with anti-staphylococcal antibiotics (SAbx) for a non-CoNS infection, or treated for CoNS with non-SAbx were excluded. Pts were categorized by number of pos BCx (1 vs ≥2). In each period, a random sample of pts was screened until 50 pts with 1 CoNS pos BCx were included. Additional data were collected until at least 50 pts with ≥2 pos BCx were included in each period. The primary outcome was use of SAbx among pts in each group before and after species reporting. Additional analyses were performed to compare the use of SAbx among subsets with same/different species and/or susceptibilities.

Results

203 pts were included, 102 before and 101 after. 51% and 50% had ≥2 pos BCx in the before and after groups, respectively. S. epidermidis was isolated more frequently in pts with ≥2 pos BCx (75% vs 50%, p< 0.001). 77% of pts received at least 1 SAbx (97% vancomycin). Median SAbx days of therapy per pt (DOTs) was greater among pts with ≥2 pos BCx (1 vs 5, p< 0.001). There was no difference in overall DOTs between the two periods (3 vs 2, p=0.25). However, among pts with ≥2 pos BCx, median DOTs was less in the after period (6.5 vs 3, p=0.016). Among pts with 1 pos BCx, median DOTs was 1 in both periods.

Median Anti-Staphylococcal Antibiotic Days of Therapy per Patient (≥ 2 positive cultures)

Conclusion

CoNS species reporting was associated with decreased SAbx use for pts with ≥2 pos BCx, suggesting that knowing the species helps in determining likelihood of true infection. Institutions may realize improved stewardship metrics of SAbx by implementing CoNS species reporting for pos BCx.

Disclosures

Tyler J. Stone, PharmD, Paratek (Research Grant or Support) Elizabeth Palavecino, MD, Paratek (Grant/Research Support)Paratek (Grant/Research Support) John Williamson, PharmD, Paratek (Research Grant or Support)

1600. Closing the gap on moxifloxacin breakpoints for Stenotrophomonas maltophilia

Background

Moxifloxacin (MOX) has in vitro activity against Enterobacterales and Stenotrophomonas maltophilia (SM). Although MOX commonly displays lower minimum inhibitory concentration (MIC)_50/90 values against SM when compared to levofloxacin, there are currently no established MOX breakpoints for treatment of SM. The Clinical and Laboratory Standards Institute (CLSI) has established interpretive categories and MIC breakpoints for levofloxacin (S ≤2µg/ml) against SM. The US Food and Drug Administration and European Committee on Antimicrobial Susceptibility Testing provide MOX breakpoints for Enterobacterales with susceptible MICs represented at ≤ 2 µg/mL and ≤ 0.25 µg/mL, respectively. The purpose of this study was to evaluate MOX MIC distribution against SM strains recovered from clinical specimens.

Methods

Clinical samples from patients with suspected infection during calendar year 2018 and 2019 were processed in the microbiology lab of Wake Forest Baptist Medical Center. After incubation, SM colonies were identified by MALDI-TOF system. MOX susceptibility testing was performed for these clinical isolates by gradient diffusion strip methodologies. Results were displayed as MIC (µg/mL) without interpretation. MIC_50/90 and susceptibility rates at potential breakpoints were calculated.

Results

A total of 211 isolates were tested, 112 from 2018 and 99 from 2019. MOX MIC₅₀ and MIC₉₀ for all isolates was 0.25 µg/mL and 2 µg/mL, respectively. The range of MIC distribution was ≤ 0.006 µg/mL to ≥ 64 µg/mL. Percent susceptibilities at incremental MICs, including established MOX breakpoints against Enterobacterales and established levofloxacin breakpoints against SM, are represented in Table 1. MIC distribution was plotted in Figure 1.

Table 1. Susceptibility rates of S. maltophilia to moxifloxacin at theoretical breakpoints

Figure 1. Moxifloxacin MIC Distribution against All S. maltophilia Isolates

Conclusion

With no established breakpoint, these data represent one of the largest samples of MOX MICs against SM in the United States. Using the CLSI breakpoint for levofloxacin in SM (MIC of ≤2ug/ml) the overall susceptibility rate is 93%. This finding highlights the importance of performing susceptibility testing to this agent by the microbiology laboratory and the critical need for MOX breakpoints in SM.

Disclosures

Tyler J. Stone, PharmD, Paratek (Research Grant or Support) John Williamson, PharmD, Paratek (Research Grant or Support) Elizabeth Palavecino, MD, Paratek (Grant/Research Support)Paratek (Grant/Research Support)

838. Drivers of empiric carbapenem use: How important is history of extended-spectrum beta-lactamase (ESBL) infection?

Background

CARs are first line agents for serious infections caused by ESBL producers. Likelihood of developing subsequent ESBL infection is unknown. In patients (pts) with a history (hx) of ESBL positive (ESBLP) culture, empiric therapy with a CAR has become common in hospitals. The purpose of this study was to evaluate the microbiology of subsequent infections (SI) among pts with hx of ESBLP culture and determine risk factors associated with ESBLP SI that may justify an empiric CAR.

Methods

This retrospective observational study was conducted at a multicenter health system. The electronic medical record (EMR) was used to generate a report of all E. coli (EC) or K. pneumoniae (KP) ESBLP cultures during 2017, an analogous report was generated for ESBL-negative (ESBLN) EC or KP. These were termed index cultures (IC). Pts were randomly selected from each report until 200 total pts were enrolled. Inpatients, outpatients, and all culture specimens were included. Pts with an ESBLP culture prior to 2017 were excluded. The EMR was reviewed up to 1 year after the IC. Pt and culture characteristics were recorded. The primary outcome was proportion of pts who developed an ESBLP SI. Risk factors associated with ESBLP SI were determined. Relapsed infection (same site, same bacteria) that occurred within 2 weeks of the IC was excluded.

Results

200 pts were included, 100 with ESBLP IC and 100 with ESBLN IC. The mean age was 58 years, 84% were female, and 69% were outpatients. 86% of IC were EC and 86% were urine specimens. Within 1 year of IC, 100 pts (50%) developed a SI. 22 of these were ESBLP, 43 were ESBLN, and 35 had no or negative culture. The mean time since IC for ESBLP SI and ESBLN SI was 85 (26-226) days and 140 (15-363) days, respectively (p=0.014). When comparing time to SI, 21 (96%) ESBLP and 26 (61%) ESBLN occurred < 6 months after IC (p=0.003). Among SI with culture data (n= 65), the number of ESBLP SI was higher if the IC was ESBLP (22 vs 0, p< 0.001). Incidence of ESBLP or ESBLN SI in all pts with an ESBLP IC was similar (22 vs 18, p=0.428). Factors associated with ESBLP SI were hx of ESBLP IC, male gender, and time between IC and SI.

Table 1. Index Culture Characteristics of Culture Positive Subsequent Infections

Figure 1. Cumulative rate of ESBL-positive SI in 180 days (6 months) following IC

Table 2. Univariate Analysis of Patient Characteristics Comparing ESBL-positive and ESBL-negative Culture Positive Subsequent Infections

Conclusion

Hx of positive culture for ESBL-producing EC or KP is associated with SI caused by ESBLP EC or KP. Pts presenting < 6 months after ESBLP IC are at increased risk for ESBLP SI, justifying empiric CAR therapy.

Disclosures

Tyler J. Stone, PharmD, Paratek (Research Grant or Support) Elizabeth Palavecino, MD, Paratek (Grant/Research Support)Paratek (Grant/Research Support) John Williamson, PharmD, Paratek (Research Grant or Support)

Application, Verification, and Implementation of SARS-CoV-2 Serologic Assays with Emergency Use Authorization

Interest continues to grow regarding the role of serologic assays for the detection of prior infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The U.S. Food and Drug Administration (FDA) has granted emergency use authorization (EUA) status to many SARS-CoV-2 serologic assays. In this document, expert recommendations from clinical microbiologist members of the American Society for Microbiology (ASM) concerning detailed verification strategies for SARS-CoV-2 serologic assays with FDA EUA are provided, as are insights into assay limitations and reporting considerations for laboratories. Assessments concerning single-antibody and multiantibody isotype detection assays, which may provide either differentiated or nondifferentiated (i.e., total antibody) antibody class results, are addressed. Additional considerations prior to assay implementation are also discussed, including biosafety, quality control, and proficiency testing strategies. As the landscape of SARS-CoV-2 serologic testing is rapidly changing, this document provides updated guidance for laboratorians on application of these assays.

Fatal sepsis associated with a storage container leak permitting platelet contamination with environmental bacteria after pathogen reduction

BACKGROUND

Pathogen reduction technology and enhanced bacterial culture screening promise to significantly reduce the risk of transfusion-associated septic reactions due to contaminated platelets. Recent reports suggest that these interventions lack efficacy for post-collection and processing contamination with environmental organisms if the storage bag integrity is compromised.

CASE REPORT

We report a fatal septic transfusion reaction in a 63-year-old patient with chronic kidney and liver disease who received a pathogen reduced platelet transfusion in anticipation of surgery.

METHODS

The residual platelet concentrate was cultured, with the detected microorganisms undergoing 16S genotype sequencing. Separate pathogen reduction studies were performed on the recovered bacteria, including assessment for amotosalen photoproducts. The storage container was subjected to pressure testing and microscopic examination. Environmental culture screening was performed at the hospital.

RESULTS

Gram negative rods were detected in the platelet unit and cultures of both platelet component and the patient's blood grew Acinetobacter baumannii complex, Leclercia adecarboxylata and Staphylococcus saprophyticus. These strains were effectively inactivated with >7.2, 7.7, and >7.1 log₁₀ kill, respectively. The platelet storage container revealed a leak visible only on pressure testing. Hospital environmental cultures were negative and the contamination source is unknown. A. baumannii complex and S. saprophyticus 16S genotyping sequences were identical to those implicated in a previously reported septic reaction.

CONCLUSION

Findings are compatible with post-processing environmental contamination of a pathogen reduced platelet concentrate via a non-visible, acquired storage container leak. Efforts are warranted to actively prevent damage to, and detect defects in, platelet storage containers, and to store and transport components in clean environments.

Secondary syphilis mimicking sarcoidosis

Secondary syphilis may mimic sarcoidosis due to atypical clinical and pathological presentations. Differential diagnosis of these two is critical since the clinical courses and treatments are different. Highly clinical suspicion and utilization of confirmatory tests in high-risk patients are the key for the differential diagnosis.

Naegleria Fowleri Diagnosed with Hospital Autopsy in a Toddler: A Case Study

Casestudy

Naegleria fowleri, an amoeba, is typically found in warm freshwater lakes, ponds, rivers and hot springs. It is responsible for causing the incredibly rare and lethal central nervous system infection called Primary Amoebic Meningoencephalitis (PAM). In the United States, 145 confirmed cases have been documented since 1962. Most cases are associated with freshwater lakes, ponds and reservoirs, while only a handful have been linked to artificial recreational venues such as pools, interactive water play-grounds, and spas. In addition to highlighting a rare amoebic disease, this case illustrates the continued importance of hospital autopsies especially given recent ruling to eliminate the autopsy requirement by the Centers for Medicare and Medicaid Services.

Results

An otherwise healthy toddler had upper respiratory symptoms and otitis media days after returning from an artificial recreational water venue, becoming increasingly lethargic and febrile over the next few days. At the hospital, cerebrospinal fluid (CSF) abnormalities were suggestive but not consistent with bacterial meningitis. A meningoencephalitis panel, a Computed Tomograph (CT) scan of the head, and chest-x-ray were negative for abnormalities. Appropriate antimicrobial therapy was initiated. Three days after hospital admission, his symptoms worsened including development of dysconjugate gaze and signs of cerebellitis. He became increasingly hemodynamically unstable, suffered an arrest, and passed away days later.

Conclusion

Since this death did not fall under the state’s statutes mandating medicolegal autopsy, a hospital- requested autopsy was performed. Cerebral edema and a light gray to light green exudate was along the inferior and lateral left temporal lobe, brain stem, and cerebellum. An exuberant lymphoplasmacytic infiltrate with scattered polymorphonuclear leukocytes expanded the meninges. Small histiocyte-like cells with distinct eccentric nuclei and granular, vacuolated cytoplasm, confirmed by Centers for Disease Control and Prevention (CDC) to be Naegleria fowleri, were best visualized in the Virchow-Robin spaces and deeper parenchyma.

Evaluation of the performance of DiaSorin molecular Pneumocystis jirovecii-CMV multiplex real-time PCR assay from bronchoalveolar lavage samples

The aim of this study was to evaluate the performance of the DiaSorin Molecular PJ-CMV multiplex real-time PCR (PJ-CMV PCR) assay (DiaSorin Molecular LLC, USA) in bronchoalveolar lavage (BAL) samples compared to direct immunofluorescence assay (IFA) for the detection of Pneumocystis jirovecii and assess CMV and P. jirovecii co-infection rate in immunosuppressed patients with suspected pneumonia. A total of 125 BAL samples from immunosuppressed patients submitted for PJP-IFA were tested. Surplus samples were saved and further tested by using the PJ-CMV PCR assay. Among the 125 samples, P. jirovecii was detected in 31.2% (39/125) and in 40% (50/125) of the specimens using IFA and PJ-CMV PCR respectively. Eleven of the PJ-CMV PCR positive samples were negative by direct IFA for P. jirovecii. All samples positive by direct IFA were also positive by PJ-CMV PCR. Using the direct IFA as a gold standard, the PJ-CMV PCR sensitivity, specificity, positive predictive value and negative predictive value for detection of P. jirovecii were 100%, 87.2%, 78% and 100%, respectively. However, after reviewing the clinical diagnosis, the specificity and PPV increased to 100%. Of the 50 P. jirovecii samples positive by PJ-CMV PCR, 18 (36%) were also positive for CMV by the PJ-CMV PCR. The co-infection rate was found to be 37.5% (6/16) and 35.2% (12/34) in HIV infected and non-HIV infected patients. This study indicated that the DiaSorin Molecular PJ-CMV multiplex real-time PCR assay has higher sensitivity than direct IFA for detection of P. jirovecii and provides rapid detection of PJ and CMV infection in BAL samples.

Intermittent occurrence of health care-onset influenza cases in a tertiary care facility during the 2017-2018 flu season

Health care-onset influenza (HOI) poses a major risk for hospitalized patients. During the 2017-2018 season, 37 HOI cases out of 382 inpatients (9.7%) with influenza were detected in a tertiary care hospital. HOI and community-onset influenza cases peaked simultaneously, and employee absenteeism was delayed by 1 month. A HOI to community-onset influenza case-comparison revealed associations with placement in rehabilitation, leukocytosis, health care-associated infections, and elevated mortality rates. Interventions should be selected based on the epidemiology of influenza occurrence.

2249. Impact of Minimum Inhibitory Concentration on Clinical Outcomes of Daptomycin for VRE Bloodstream Infection Among Neutropenic Oncology Patients

Background

Vancomycin-resistant Enterococcus (VRE) bloodstream infection (BSI) is a significant cause of morbidity and mortality in immunocompromised patients. This study aimed to assess the impact of daptomycin (DAP) MIC on outcomes of treatment for VRE BSI in neutropenic oncology patients.

Methods

This was a retrospective, observational, single-center, cohort study at an academic medical center. Included: age ≥ 18, neutropenia, admitted to oncology unit, and DAP for VRE BSI. Excluded: death within 24 hours after initiation of DAP, polymicrobial BSI, and linezolid use for > 48 hours before DAP initiation. Patients with VRE BSI 2008–2018 were identified using a report from the micro lab. Data were collected by electronic medical record review. The primary outcome of the study was clinical success, defined as culture sterilization, hypotension resolution, defervescence, and no need to change DAP due to persistent signs/symptoms of infection. Patients were analyzed according to DAP MIC ≤ 2 vs. ≥ 4 mg/L. Multivariable logistic regression analysis was performed to identify factors associated with clinical success.

Results

44 patients met study criteria (MIC ≤ 2, n = 26; MIC ≥ 4, n = 18). Mean age was 58 years, 59% were male, and median ANC was 0. Median Charlson Comorbidity Index Score and Pitt Bacteremia Score (Pitt) were 5 and 1, respectively. 34% required ICU admission. More patients achieved clinical success with MIC ≤ 2 (88% vs. 56%; P = 0.03). Time to success (2.4 vs. 4 days, P = 0.02) and time to culture sterilization (2.2 vs. 2.9 days, P = 0.24) were shorter with MIC ≤ 2. Mortality was similar between groups (31% vs. 33%). Time to culture sterilization (P = 0.008), neutropenia resolution (P = 0.02), MIC group (P = 0.096), and Pitt (P = 0.52) were included in the multivariable model.

Conclusion

DAP MIC should be considered when choosing therapy for VRE BSI among neutropenic oncology patients, particularly those expected to have prolonged neutropenia and those with persistently positive cultures.

Disclosures

All authors: No reported disclosures.

Multilab evaluation of delafloxacin MIC Test Strip against Gram-negative and Gram-positive organisms

The performance of the delafloxacin MIC Test Strip (MTS) was evaluated. Three testing sites collected/tested clinical isolates, and 1 site tested challenge isolates that together total 224 S. aureus, 36 S. haemolyticus, 23 S. lugdunensis, 105 E. faecalis, 308 Enterobacteriales, and 140 P. aeruginosa. MIC testing was performed by broth microdilution (BMD) and MTS. Each site also tested 20 common isolates in triplicate on 3 days by MTS and 20 replicates of 4 QC strains by MTS and BMD. MTS results for consolidated clinical/challenge isolates were within 1 doubling dilution of the BMD MIC for 96.9% of S. aureus; 100% of S. haemolyticus, S. lugdunensis, and E. faecalis; 98.4% of Enterobacteriales; and 97.9% of P. aeruginosa. All reproducibility results were within 1 dilution of the modal MIC. All BMD and MTS results for the QC strains were within expected ranges. Overall, the delafloxacin MTS performed similar to BMD.

Microbial stability of syringes of anesthetic drugs prepared in the operating room

STUDY OBJECTIVE

To determine whether microbial contamination of anesthesia syringes prepared in the operating room (OR) become contaminated in a time-dependent fashion.

DESIGN

Observational.

SETTING

Operating suite in a major university hospital.

PATIENTS

None (in vitro study). 400 syringes were studied for microbial contamination.

INTERVENTIONS

Syringes prepared in the OR by anesthesia personnel were sampled at 1, 2, 3, or 4 h in a sterile fashion and sent to the microbiology laboratory for quantitative culture of any bacteria.

MEASUREMENTS

Colony forming units (CFU) per mL of drug were calculated and any identified positive cultures were identified by Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry. Logistic regression was used to test the effect of time since preparation on prevalence of positive culture, as was the effect of number of accesses of the syringe and identity of the drug.

MAIN RESULTS

Overall, 9/400 (2.25%) syringes were positive for bacteria. The median (interquartile range [IQR]) concentration of bacteria among positive cultures was 100 (100,100) CFU. All cultured species were generally nonpathogenic common contaminants. There was no effect of time since preparation, number of accesses of the syringe at the time of sampling, or drug identity (propofol vs. other).

CONCLUSIONS

Contamination of anesthesia syringes is uncommon and occurs at a low overall concentration of bacteria. Contamination does not appear to be time related, and thus calls into question the reasonableness of USP Chapter 797's one-hour requirement.

1799. Impact of Real-Time Electronic Notifications to Pharmacists of Rapid Diagnostic Blood Culture Results

Background

Rapid diagnostic tests that utilize multiplex PCR technology provide faster time to pathogen identification, but maximizing the impact on outcomes is dependent upon who is available to respond to test results. In June 2017, pharmacists began receiving in-basket notifications of positive results from the institution’s FilmArray BCID assay. The objective of this study was to determine the impact on antibiotic utilization associated with this method of communicating results.

Methods

This was a retrospective, observational, before-and-after study at an academic medical center with an established stewardship program. Inclusion criteria: Adult patients age ≥18 admitted to an ICU or oncology unit with ≥1 positive blood culture containing a gram-positive organism identified by FilmArray BCID. Patients with polymicrobial infection, concomitant infection caused by a different organism, antibiotics started before admission, or death prior to organism identification were excluded. Data were collected during a 4-month period before (PRE) and a 4-month period after (POST) implementation of in-basket notifications. Stewardship metrics and other outcome measures were compared between the two groups. Pharmacists received no targeted stewardship training on how to respond to results.

Results

Ninety-two patients met study criteria (49 PRE and 43 POST). Patients were age 62 ± 16, male (55%), and 77 (84%) were located in an ICU. Median Charlson Comorbidity Index was 4 and Pitt Bacteremia Score was 1. Sixty-seven patients were considered to have noncontaminant bloodstream infection. Median results for these patients are listed in the table. Patients with contaminants (n = 25) had 3.5 and 7 antibiotic-free days in the PRE and POST groups, respectively (P = 0.34).

Conclusion

In-basket notifications did not significantly improve antibiotic utilization or clinical outcomes. Active interventions and antimicrobial stewardship initiatives are needed in combination with rapid diagnostic tests.

Disclosures

All authors: No reported disclosures.

1877. Discrepant Susceptibilities Have Minimal Impact on Antibiotic Prescribing for Patients With Two or More Blood Cultures Positive for Coagulase-Negative Staphylococci

Background

CoNS are common blood culture (BCx) contaminants resulting in unnecessary antibiotic therapy. Species reporting of CoNS is now possible in many medical centers due to new technology. When CoNS are isolated from multiple BCx, factors such as different susceptibility patterns and/or different species might suggest contamination. The purpose of this study was to characterize antibiotic usage attributable to CoNS positive BCx and to determine whether reporting of CoNS species could help reduce unnecessary antibiotics.

Methods

Inpatients from January to June 2017 at our institution were screened retrospectively. During the study period, CoNS species were not reported (except S. lugdunensis). Patients (patients) ≥18 years old with ≥1 BCx positive for CoNS were included. Patients who were neutropenic, treated with staphylococcal antibiotics (SAbx) for a non-CoNS infection, or treated for CoNS with an antibiotic other than the defined SAbx were excluded. Patients were categorized into pre-defined groups: single positive BCx(Group 1), ≥2 positive BCx with different (Group 2) or same (Group 3) susceptibilities. A random sample of patients was screened until 50 Group 1 patients met study criteria. Additional data were collected on all remaining Group 2 and 3 patients in the study period, including species name obtained from laboratory database. The primary outcome was attributable use of SAbx among patients in each group. Additional analyses were performed to compare the use of SAbx among Groups 2 and 3.

Results

One hundred two patients were included. In the random sample (n = 76), 34% had ≥2 positive BCx. S. epidermidis was isolated more frequently in Groups 2 and 3 than in Group 1 (69% vs. 52%, P = 0.03). 74% of patients received at least 1 SAbx (97% vancomycin). Attributable use of SAbx was greater among Groups 2 and 3 (P < 0.001, figure). Differing susceptibilities occurred in 24/52 (46%) patients but did not impact SAbx use (P = 0.57 for DOTs, P = 0.35 for DDDs). Seventeen (33%) of patients with ≥2 positive BCxhad different species.

Conclusion

Significantly more SAbx were prescribed when ≥2 BCx were positive for CoNS. Since differences in susceptibilities has little effect, future studies should evaluate the impact of reporting CoNS species on appropriate antibiotic prescribing.

*P < 0.001 for Group 1 vs. 2 and Group 1 vs. 3 (DOTs and DDDs). P = NS for Group 2 vs. 3.

Disclosures

All authors: No reported disclosures.

Double invasive fungal infection due to dematiaceous moulds in a renal transplant patient

Alternaria and Verruconis are two dematiaceous moulds that occasionally cause disease in immunocompromised hosts. We present the case of a 58-year-old man with history of deceased donor renal transplantation 14 months prior, who presented with fevers and cough. He was found to have right upper lobe pneumonia and a non-healing eschar of his right knee. Dematiaceous fungi grew from bronchoalveolar lavage (BAL) and was sent to reference lab for identification. Meanwhile, the eschar on his right knee was biopsied and grew Alternaria spp. Pathology was consistent with invasive mould infection and he was treated as having disseminated Alternaria infection with voriconazole and amphotericin B lipid complex. Later on, the dematiaceous mould from a BAL specimen was identified as Verruconis gallopava The patient was discharged on voriconazole awaiting minimal inhibitory concentrations for V. gallopava but was readmitted 2 days later with high fevers and died from acute respiratory failure.

Case Report: Strongyloides stercoralis Hyperinfection in a Patient with Chronic Lymphocytic Leukemia

Strongyloides stercoralis is an intestinal nematode that can cause disseminated infection in an immunocompromised host. It is most commonly acquired in developing countries. It was previously a common infection in many parts of the United States, particularly in the Appalachian region, but is rarely identified currently. Here, we describe a patient born and raised in Appalachia, with no history of travel outside the United States, who presented with chronic lymphocytic leukemia and S. stercoralis hyperinfection characterized by acute respiratory failure, altered mental status, and extended-spectrum-beta-lactamase Klebsiella pneumoniae bacteremia. Despite prompt identification of the parasite on sputum microscopy and initiation of therapy with oral ivermectin and meropenem, the patient subsequently died. This case highlights the continued possibility of S. stercoralis infection in patients from Appalachia.

The Impact of Diagnostic Stewardship on Clostridium difficile Infections

Background

Clostridium difficile infections (CDI) pose a growing threat to hospitalized patients. This study assesses the impact of changing from a nucleic acid amplification test (NAAT) to a stepwise testing algorithm (STA) by using an enzyme immunoassay (GDH and toxin A/B) and confirmatory NAAT confirmation in specific cases.

Methods

In an 885 bed academic medical center a 24 month pre-/post design was used to assess the effect of the STA for the following parameters: rates of enterocolitis due to C.diff (CDE), NHSN C.diff LabID events, CDI complications, mortality, antimicrobial prescription patterns, cluster occurrences; and testing, treatment, and isolation costs. Inpatient data were extracted from ICD-9/10 diagnosis codes, infection prevention, and laboratory databases.

Results

The STA significantly decreased the number of CDE ICD9/10 codes, HO, CO, and CO-HCFA C.diff LabID event rates by 65%, 78%, 75%, and 75%, respectively. Similar reductions were noted for associated complications such as NHSN defined colon surgeries (-61%), megacolon (-64%), and acute kidney failure (-55%). CDE unrelated complication rates for colon surgeries and acute kidney failure remained constant while the diagnosis of megacolon decreased but not significantly (-71%; P > 0.05). Inpatient mortality did not change with or without CDE. Significant reductions were observed in the use of oral metronidazole (total: -32%; CDE specific: -70%) and vancomycin (total: -58%; CDE specific: -61%). There were no clusters detected pre-/post STA introduction. The need for isolation decreased from 748 to 181 patients post-intervention (-76%; P < 0.05). Annual cost savings were over $175,000 due to decreases in laboratory testing followed by isolation, and antibiotic use.

Conclusion

The switch to an STA from NAAT did not affect the diagnosis, treatment, or control of clinically relevant CDI in our institution. Benefits included avoidance of unnecessary antibiotic treatment, reduction in isolation, achieving publicly reported objectives, and costs savings. Selection of clinically relevant tests can help to improve hospitalization and treatment of patients and should be considered as part of diagnostic stewardship.

Disclosures

All authors: No reported disclosures.

Candida pararugosa: First Reported Bloodstream Infection in an Adult

Candida pararugosa is a yeast that has been previously isolated in various human specimens. The first reported isolation was from human feces in 1998, with subsequent reports of positive cultures from the oral cavity where it was thought to represent colonization rather than true infection. Though it has been isolated from other human sites, its clinical significance and manifestations are poorly characterized. We report the case of a 39-year-old woman on parenteral hyperalimentation who developed post abdominal surgery sepsis and surgical wound necrotizing fasciitis. Candida pararugosa was isolated from two different blood cultures and the patient's clinical status improved after initiation of therapy with micafungin. Though it was not clear whether sepsis was driven by the candidemia or the necrotizing fasciitis or both, this report appears to be the first case of Candida pararugosa bloodstream infection described in an adult.

Estimating the Burden of Pandemic Infectious Disease: The Case of the Second Wave of Pandemic Influenza H1N1 in Forsyth County, North Carolina

BACKGROUND

Understanding the burden of influenza A(H1N1)pdm09 virus during the second wave of 2009-2010 is important for future pandemic planning.

METHODS

Persons who presented to the emergency department (ED) or were hospitalized with fever and/or acute respiratory symptoms at the academic medical center in Forsyth County, North Carolina were prospectively enrolled and underwent nasal/throat swab testing for influenza A(H1N1)pdm09. Laboratory-confirmed cases of influenza A(H1N1)pdm09 virus identified through active surveillance were compared by capture-recapture analysis to those identified through independent, passive surveillance (physician-ordered influenza testing). This approach estimated the number of total cases, including those not captured by either surveillance method. A second analysis estimated the total number of influenza A(H1N1)pdm09 cases by multiplying weekly influenza percentages determined via active surveillance by weekly counts of influenza-associated discharge diagnoses from administrative data. Market share adjustments were used to estimate influenza A(H1N1)pdm09 virus ED visits or hospitalizations per 1,000 residents.

RESULTS

Capture-recapture analysis estimated that 753 residents (95% confidence interval [CI], 424-2,735) with influenza A(H1N1)pdm09 virus were seen in the academic medical center from September 2009 through mid-April 2010; this result yielded an estimated 4.7 (95% CI, 2.6-16.9) influenza A(H1N1)pdm09 virus ED visits or hospitalizations per 1,000 residents. Similarly, 708 visits were estimated using weekly influenza percentages and influenza-associated discharge diagnoses, yielding an estimated 4.4 influenza A(H1N1)pdm09 virus ED visits or hospitalizations per 1,000 residents.

CONCLUSION

This study demonstrates that the burden of influenza A(H1N1)pdm09 virus in ED and inpatient settings by capture-recapture analysis was 4-5 per 1,000 residents; this rate was approximately 8-fold higher than that detected by physician-ordered influenza testing.

Prevalence of Community-Acquired Methicillin-Resistant Staphylococcus aureus Nasal Colonization Among Children

BACKGROUND

Invasive infections from community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are increasingly being encountered in healthy children. Nasal colonization of MRSA is associated with increased risk for acquiring invasive disease. The objective of this study was to determine prevalence and risk factors for CA-MRSA nasal colonization among a healthy paediatric population and to determine antibiotic susceptibilities of S. aureus isolates.

MATERIALS AND METHODS

Using a cross-sectional study design, children aged 1mnth-17y attending well-child clinic at an academic hospital and a local public school in Mangalore, India were screened for S. aureus colonization via nasal swabs. A questionnaire was administered and data on risk factors for nasal colonization was collected. Samples were obtained from the anterior nares and cultured quantitatively. S. aureus isolates were confirmed by growth on selective media and coagulase testing. Disk diffusion antibiotic susceptibility tests were performed according to Clinical and Laboratory Standard Institute guidelines.

RESULTS

Of the 500 children included in the study, S. aureus was isolated from the anterior nares in 126 (25%) children; four (3%) isolates were classified as CA-MRSA. Factors associated with S. aureus nasal colonization were children <6 y old (p=0.030) and members of joint families (p=0.044). Resistance to many classes of antibiotics were noted among S. aureus isolates including trimethoprim-sulfamethoxazole (39%), ciprofloxacin (16%), erythromycin (19%) and clindamycin (5%). Inducible clindamycin resistance (positive D test) was detected in 11 of the erythromycin-resistant strains not already classified as resistant to clindamycin. No resistance to vancomycin was observed.

CONCLUSION

Children in India have a high rate of nasal colonization of S. aureus. Nasal colonization of community-associated methicillin-resistant S. aureus exists but is still low among healthy children. The high rate of resistance to many classes of antibiotics among S. aureus strains is of great concern warranting continued surveillance and antimicrobial stewardship.

The effect on peritoneal dialysis pathogens of changing topical antibiotic prophylaxis

BACKGROUND

Prophylactic gentamicin 0.1% cream has demonstrated efficacy in preventing both exit-site infection (ESI) and peritonitis attributable to gram-positive and gram-negative organisms; however, the effect of this practice on the gentamicin susceptibility patterns of bacterial pathogens isolated from such infections is unknown. We therefore examined the effect of a change in our prophylactic topical antibiotic exit-site protocol (from mupirocin 2% cream to gentamicin 0.1% cream) on infection rates and susceptibility patterns.

METHODS

This retrospective observational cohort study examined two periods of time: before and after the change in exit-site protocol. Each period was 30 months in duration, with a 2-month implementation period between, during which patient data were excluded. Demographic, clinical, and microbiology data were collected for each patient and episode of infection.

RESULTS

Overall, 377 patients were evaluated. In the mupirocin period (MUP), 145 infections occurred in 79 patients, and in the gentamicin period, 145 infections occurred in 93 patients. No significant effect was found either in overall episodes of infection (0.53 per year) or in episodes of peritonitis (0.429 vs 0.375 per year), but episodes of ESI increased significantly (0.098 vs 0.153 per year; p = 0.024; odds ratio: 1.55; 95% confidence interval: 1.05 to 2.28). Episodes of Staphylococcus aureus peritonitis increased by 38% (0.018 vs 0.025 per year), and episodes of S. aureus ESI increased significantly by 150% (0.022 vs 0.055 per year; p = 0.03; hazard ratio: 3.00; 95% confidence interval: 1.09 to 8.26). Episodes of pseudomonal peritonitis declined by 68% (0.022 vs 0.007 per year), and episodes of pseudomonal ESI increased by 150% (0.007 vs 0.018 per year). The gentamicin susceptibility for gram-positive isolates demonstrated no significant change; however, the gentamicin susceptibility for Enterobacteriaceae decreased by 12% and for Pseudomonas, by 14%.

CONCLUSIONS

The significant increase in episodes of ESI and the decrease in susceptibility for both Enterobacteriaceae and Pseudomonas isolates represent a concerning trend. Centers should examine trends in infection rates and in bacterial susceptibilities to determine the most appropriate agent for ESI prophylaxis.

Blood drawn through valved catheter hub connectors carries a significant risk of contamination

Infection Control became concerned when bloodstream infection (BSI) rates increased after implementing a needleless valved hub connector. During a 21-month period three different needleless catheter hub connectors were evaluated by quantitatively culturing blood drawn through hub connectors that would have ordinarily been discarded (DBC). DBC drawn through Clearlink™ catheter hub connectors were found to be twice as likely to be positive as DBC drawn through Clave® or Q-syte™ hub connectors (P < 0.04). DBC grew pathogens 46% of the time and skin organisms 54% of the time. Patients with positive DBC were three times more likely to meet Centers for Disease Control (CDC) BSI criteria by DBC cultures than by physician-ordered blood cultures (CBC; P < 0.001). For patients growing pathogens in DBC, 64% had no CBC drawn, the average temperature was lower than for patients with pathogens in CBC (99.3 ± 1.5 ve 100.6 ± 1.9, P = 0.015), and 92% of discharged patients (11 out of 12) were not treated with an antibiotic active against the DBC pathogen. Drawing BC through a catheter hub connector carries a risk of false-positives that could increase BSI rates by up to 3-fold. Further work is necessary to evaluate this concern.

Effects of antibiotic-impregnated external ventricular drains on bacterial culture results: an in vitro analysis

OBJECT

Treatment of ventriculoperitoneal shunt infections frequently requires placement of an external ventricular drain (EVD). Surveillance specimens obtained from antibiotic-impregnated (AI) EVDs may be less likely to demonstrate bacterial growth, potentially resulting in undertreatment of an infection. The purpose of this study was to assess whether AI EVDs had any significant effect on bacterial culture results compared with nonantibiotic-impregnated (NAI) EVDs.

METHODS

In vitro assays were performed using AI EVDs containing minocycline and rifampin (VentriClear II, Medtronic) and NAI EVD controls (Bioglide, Medtronic). The presence of antibiotics was evaluated via capillary electrophoresis of sterile saline drawn from AI and NAI EVDs after predefined incubation intervals. Antimicrobial activity was assessed by evaluating zones of inhibition created by the catheter aspirates on plates inoculated with a quality control strain of Staphylococcus epidermidis (American Type Culture Collection strain 12228). To determine the effects of cultures drawn through AI compared with NAI EVDs, the quality control strain was then incubated within 4 new AI and 4 new NAI EVDs for predefined intervals before being plated on culture media. Spread and streak plate culture results from each type of catheter were compared at each time interval.

RESULTS

Capillary electrophoresis showed that more minocycline than rifampin was eluted from the AI EVDs. Sterile saline samples incubated within the AI EVDs demonstrated zones of growth inhibition when placed on plates of S. epidermidis at all time intervals tested. No zones of inhibition were noted on NAI EVD control plates. When a standardized inoculum of S. epidermidis was drawn through AI and NAI EVDs, antimicrobial effects were observed after incubation in the AI EVD group only. Colony counting demonstrated that significantly fewer colonies resulted from samples drawn through AI compared with NAI EVDs at the multiple time intervals. Similarly, streak plating yielded a statistically significant number of false-negative results from AI compared with NAI EVDs at 2 time intervals.

CONCLUSIONS

The findings in the current study indicate that the risk of a false-negative culture result may be increased when a CSF sample is drawn through an AI catheter. In the management of a known shunt infection, a false-negative result from an EVD culture specimen may lead to an inappropriately short duration of antibiotic therapy. These data have significant clinical implications, particularly given the widespread use of AI drains and the current high rates of shunt reinfection after EVD use worldwide.

Epidemiology of respiratory syncytial virus in various regions within North Carolina during multiple seasons

BACKGROUND

The Centers for Disease Control and Prevention (CDC) monitors the occurrence of respiratory syncytial virus (RSV) in the United States and has historically reported on activity at the regional level. Prior to the 2007-2008 RSVseason, the CDC did not report seasonal RSV data for cities within North Carolina or for the state. The purpose of the present study is to characterize RSV seasonal activity within North Carolina and to determine the appropriate months in which at-risk children should receive prophylaxis.

METHODS

We prospectively collected RSV test data monthly over three seasons (fall through spring), from September 2003 through July 2006, from a diverse group of hospitals and a community pediatric practice located within five regions throughout North Carolina.

RESULTS

Approximately 14,000 laboratory tests, including 23.7% that were RSV positive, were evaluated over the three seasons, and RSV was detected within the state during all but three months of the study. Seasonal variation in the onset (October-November) of RSV activity and duration (six to seven months) of the RSV season according to the specified definition of seasonality was noted yearly within individual regions and among regions. On average over the study period, the greatest percentage of positive tests (33.8%) statewide occurred during January.

CONCLUSIONS

Our data suggest the RSV season in North Carolina is longer than the national average, and RSV epidemics persist during months that fall outside of those in which RSV prophylaxis is given to high-risk children. Guidelines on the administration of RSV prophylaxis should ideally be based on results of local RSV test data.

Clinical, epidemiological, and laboratory aspects of methicillin-resistant Staphylococcus aureus (MRSA) infections

Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen responsible for both hospital- and community-onset disease. Resistance to methicillin in S. aureus is mediated by PBP2a, a penicillin-binding protein with low affinity to beta-lactams, encoded by the mecA gene. Accurate susceptibility testing of S. aureus isolates and screening of patients for colonization with MRSA 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 epidemiological typing of MRSA strains.

[Presence of Bartonella henselae in cats: natural reservoir quantification and human exposition risk of this zoonoses in Chile]

BACKGROUND

The availability of a serologic test for cat scratch disease in humans has allowed the diagnosis of an increasing number of cases of this disease in Chile.

AIM

To perform a serological survey for Bartonella henselae among cats in Chile.

MATERIAL AND METHODS

Blood samples from 187 cats living in three Chilean cities were obtained. IgG antibodies against Bartonella henselae were measured using indirect immunofluorescence. Blood cultures were done in 60 samples. The presence of Bartonella henselae in positive cultures was confirmed by restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR).

RESULTS

The general prevalence of IgG antibodies against Bartonella henselae was 85.6%. No differences in this prevalence were found among cats younger or older than 1 year, or those infested or not infested with fleas. However domestic cats had a lower prevalence when compared with stray cats (73 and 90% respectively, p <0.01). Bartonella henselae was isolated in 41% of blood cultures. All the isolated were confirmed as Bartonella henselae by RFLP-PCR.

CONCLUSIONS

This study found an important reservoir of Bartonella henselae in Chilean cats and therefore a high risk of exposure in humans who have contact with them.

Bacterial contamination of blood products

The occurrence of a septic reaction resulting from bacterial contamination of blood products, particularly with room-temperature stored platelets, is the most common transfusion-associated infectious risk in the United States. Bacterial contamination of blood products was first identified more than 60 years ago; yet, strategies to resolve this problem have proved daunting despite ongoing awareness and increasing concern especially in the last few years. With the recent US Food and Drug Administration (FDA) approval of culture methods for quality control testing of platelet units and the promulgation of accreditation standards by the College of American Pathologists and American Association of Blood Banks to detect bacterially contaminated platelet units and to prevent transfusion of these units, blood banks and transfusion services have finally started to address this problem, in a more standardized manner. Furthermore, as new methods of interdicting, inactivating and detecting bacterially contaminated blood products emerge, it is hoped that the problem of bacterial contamination of blood products will be overcome.