Management of Gram-Negative Bloodstream Infections in the Era of Rapid Diagnostic Testing: Impact With and Without Antibiotic Stewardship

Background

Verigene Blood-Culture Gram-Negative is a rapid diagnostic test (RDT) that detects gram-negatives (GNs) and resistance within hours from gram stain. The majority of the data support the use of RDTs with antimicrobial stewardship (AMS) intervention in gram-positive bloodstream infection (BSI). Less is known about GN BSI.

Methods

This was a retrospective quasi-experimental (nonrandomized) study of adult patients with RDT-target GN BSI comparing patients pre-RDT/AMS vs post-RDT/pre-AMS vs post-RDT/AMS. Optimal therapy was defined as appropriate coverage with the narrowest spectrum, accounting for source and co-infecting organisms. Time to optimal therapy was analyzed using Kaplan-Meier and multivariable Cox proportional hazards regression.

Results

Eight-hundred thirty-two patients were included; 237 pre-RDT/AMS vs 308 post-RDT/pre-AMS vs 237 post-RDT/AMS, respectively. The proportion of patients on optimal antibiotic therapy increased with each intervention (66.5% vs 78.9% vs 83.2%; P < .0001). Time to optimal therapy (interquartile range) decreased with introduction of RDT: 47 (7.9–67.7) hours vs 24.9 (12.4–55.2) hours vs 26.5 (10.3–66.5) hours (P = .09). Using multivariable modeling, infectious diseases (ID) consult was an effect modifier. Within the ID consult stratum, controlling for source and ICU stay, compared with the pre-RDT/AMS group, both post-RDT/pre-AMS (adjusted hazard ratio [aHR], 1.34; 95% CI, 1.04–1.72) and post-RDT/AMS (aHR, 1.28; 95% CI, 1.01–1.64), improved time to optimal therapy. This effect was not seen in the stratum without ID consult.

Conclusions

With the introduction of RDT and AMS, both proportion and time to optimal antibiotic therapy improved, especially among those with an existing ID consult. This study highlights the beneficial role of RDTs in GN BSI.

Epidemiologic and Microbiologic Characteristics of Hospitalized Patients Co-colonized With Multiple Species of Carbapenem-Resistant Enterobacteriaceae in the United States

We describe the epidemiologic and microbiologic characteristics of patients co-colonized with different species of carbapenem-resistant Enterobacteriaceae (CRE) from 5 hospitals in 4 states. Twenty-eight of 313 patients (8.9%) were co-colonized with at least 2 different CRE species. Different species within the same patient showed identical mechanism resistance in 18/28 (64%) cases.

Gastrointestinal Microbiota Disruption and Risk of Colonization With Carbapenem-resistant Pseudomonas aeruginosa in Intensive Care Unit Patients

BACKGROUND

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) colonizes the gastrointestinal tract of intensive care unit (ICU) patients, and CRPA colonization puts patients at increased risk of CRPA infection. Prior studies have not examined relationships between the microbiota, medications, and CRPA colonization acquisition.

METHODS

Data and perirectal swabs were obtained from a cohort of ICU patients at the University of Maryland Medical Center. Patients (N = 109) were classified into 3 groups by CRPA colonization-acquisition status and antimicrobial exposure. We conducted 16S ribosomal RNA gene sequencing of an ICU admission swab and ≥1 additional swab and evaluated associations between patient characteristics, medications, the gastrointestinal microbiota, and CRPA colonization acquisition.

RESULTS

ICU patients had low levels of diversity and high relative abundances of pathobionts. Piperacillin-tazobactam was prescribed more frequently to patients with CRPA colonization acquisition than those without. Piperacillin-tazobactam was associated with low abundance of potentially protective taxa (eg, Lactobacillus and Clostridiales) and increased risk of Enterococcus domination (odds ratio [OR], 5.50; 95% confidence interval [CI], 2.03-14.92). Opioids were associated with dysbiosis in patients who did not receive antibiotics; potentially protective Blautia and Lactobacillus were higher in patients who did not receive opioids. Several correlated taxa, identified at ICU admission, were associated with lower risk of CRPA colonization acquisition (OR, 0.58; 95% CI, .38-.87).

CONCLUSIONS

Antibiotics differed in their impact on the microbiota, with piperacillin-tazobactam being particularly damaging. Certain bacterial taxa (eg, Clostridiales) were negatively associated with CRPA colonization acquisition. These taxa may be markers of risk for CRPA colonization acquisition and/or serve a protective role.

The Diversity of Lipopolysaccharide (O) and Capsular Polysaccharide (K) Antigens of Invasive Klebsiella pneumoniae in a Multi-Country Collection

Klebsiella pneumoniae is a common cause of sepsis and is particularly associated with healthcare-associated infections. New strategies are needed to prevent or treat infections due to the emergence of multi-drug resistant K. pneumoniae. The goal of this study was to determine the diversity and distribution of O (lipopolysaccharide) and K (capsular polysaccharide) antigens on a large (>500) global collection of K. pneumoniae strains isolated from blood to inform vaccine development efforts. A total of 645 K. pneumoniae isolates were collected from the blood of patients in 13 countries during 2005-2017. Antibiotic susceptibility was determined using the Kirby-Bauer disk diffusion method. O antigen types including the presence of modified O galactan types were determined by PCR. K types were determined by multiplex PCR and wzi capsular typing. Sequence types of isolates were determined by multilocus sequence typing (MLST) targeting seven housekeeping genes. Among 591 isolates tested for antimicrobial resistance, we observed that 19.3% of isolates were non-susceptible to carbapenems and 62.1% of isolates were multidrug resistant (from as low as 16% in Sweden to 94% in Pakistan). Among 645 isolates, four serotypes, O1, O2, O3, and O5, accounted for 90.1% of K. pneumoniae strains. Serotype O1 was associated with multidrug resistance. Fifty percent of 199 tested O1 and O2 strains were gmlABC-positive, indicating the presence of the modified polysaccharide subunit D-galactan III. The most common K type was K2 by both multiplex PCR and wzi capsular typing. Of 39 strains tested by MLST, 36 strains were assigned to 26 known sequence types of which ST14, ST25, and ST258 were the most common. Given the limited number of O antigen types, diverse K antigen types and the high multidrug resistance, we believe that an O antigen-based vaccine would offer an excellent prophylactic strategy to prevent K. pneumoniae invasive infection.

2433. Oral Vancomycin Plus Intravenous Metronidazole for Severe Clostridioides difficile Infection in Critically Ill Patients

Background

Molecular strain 027/NAP1/BI (NAP1) is a common cause of Clostridioides difficile infections (CDI). Despite high morbidity and mortality, optimal therapy remains elusive. There is also a paucity of data regarding optimal treatment of critically ill patients with severe CDI. We aimed to determine the impact of combination therapy (intravenous metronidazole [IV MTZ] plus oral vancomycin [PO VAN]) on clinical outcomes in critically ill patients with severe CDI, including those with NAP1 CDI.

Methods

Retrospective cohort of adult patients admitted to an intensive care unit (ICU) from April 2016 to October 2018 with a positive C. difficile PCR and an order for PO VAN. Patients with an order for IV MTZ for at least 72 hours formed the combination therapy group. A subset of patients had stool samples collected for NAP1 identification via GeneXpert C. difficile Epi molecular assay. The primary outcome was 30-day in-hospital mortality. A subgroup was matched using Acute Physiology and Chronic Health Evaluation (APACHE) II Scores. Cox regression was conducted to identify variables associated with time to mortality.

Results

138 patients were included; 60 (43.5%) received IV MTZ. Patients with IV MTZ had a higher median WBC count at diagnosis (20.9 vs 15.9, P = 0.0002) and were more likely to receive a higher dose of PO VAN (31.7% vs 12.9%, P = 0.008). 42 patients had NAP1 testing, 11 were positive (26.2%). There was no difference in probability of receiving IV MTZ based on APACHE II, however, NAP1+ were more likely to receive IV MTZ (50% vs 16.7%, P = 0.049). Clinical success was higher in the monotherapy group (46.8% vs 16.7%, P = 0.002). There was no difference in mortality (20% vs 14.1%, P = 0.368). In a subgroup of patients matched by APACHE II (n = 96), mortality remained non-significantly different (18.8% vs 14.6%, P = 0.785). Adjusted for IV MTZ, APACHE II (aHR = 1.06, 95% CI 1–1.12) and number of severity criteria (aHR = 2.08, 95% CI 1.40 – 2.97) were associated with mortality. There was no difference in mortality (9.1% vs 3.2% P = 0.459) or clinical success (18.2% vs 33.7%, P = 0.283) among NAP1+ vs. NAP- patients.

Conclusion

Our data questions the utility of IV MTZ with PO VAN for ICU patients with severe CDI, including NAP1 infections. There remains a possibility for confounding by indication in our analysis.

Disclosures

All authors: No reported disclosures.

151. Comparing the Clinical Utility of Rapid Diagnostic Tests for Gram-Negative Bloodstream Infection Using a Desirability of Outcomes Ranking

Background

Rapid diagnostic testing (RDT) technology in bloodstream infections (BSI) has outpaced provider understanding of how to effectively use it. To optimize the use of RDT platforms and antibiotic therapy, decision makers must determine which RDTs to implement at their institutions. A thorough understanding of which platform to choose extends beyond simple analytic measures of sensitivities and specificities and should include a robust analysis of how these RDTs could impact clinical decisions.

Methods

Retrospective study of adult patients with Gram-negative (GN) BSI from at University of Maryland Medical Center. The clinical microbiology laboratory used Verigene® BC-GN in clinical practice. Discarded blood samples were run on BioFire® FilmArray BCID. Final organism identification/susceptibility, antibiotic exposures, and clinical outcomes were reviewed. DOOR was applied to theoretical therapy decisions based on both actual prescribing adherence to institutional algorithm recommendations; 1 being most and 6 being least desirable (Table 1). A partial credit scoring system was applied to DOOR from most (100) to least desirable (0) outcome. Comparisons were made in a paired manner.

Results

77 patients met inclusion. The median age was 58 (IQR 47, 68), 44.2% were in the ICU, and 75.3% had ID consult within 24 hours of BSI. Organism identification included: E. coli (35.1%), K. pneumoniae (23.4%), P. mirabilis (10.4%), S. marcescens (10.4%), Enterobacter spp. (9.4%), P. aeruginosa (3.9%). The only resistance determinant was CTX-M (11.6%). An antibiotic change occurred in 26.2% of cases, divided between antibiotic escalation and de-escalation. Based on the actual utilization of RDT results, median DOOR was not different between BC-GN and BCID (3 [IQR 3.4] vs. 4 [IQR 3.4], P = 0.44). Using a partial credit scoring system, the mean score was not different between platforms (49.8 [SD 26.8] vs. 47.7 [SD 20.3], P = 0.44). Through pairwise comparisons, BC-GN would have resulted in an optimal outcome of 15.3% (95% CI 4.7% to 19.3%) more often than BCID.

Conclusion

Based on the actual use of RDTs for GN BSI there was no difference in potential clinical outcomes between platforms in this relatively small sample. DOOR is a novel mechanism to quantitate clinical utility and compare RDTs.

Disclosures

All authors: No reported disclosures.

2362. Back to the Future: The Impact of Multi-Step Algorithm C. difficile Testing at a Large Tertiary Medical Center

Background

Antibiotic stewardship and infection control programs rely on C. difficile infection (CDI) test results to measure CDI incidence in the hospital setting. C. difficile carriage is common and distinguishing infection from colonization is difficult with the highly sensitive nucleic acid amplification testing (NAAT) commonly used. Current guidelines recommend a multi-step algorithm for testing. The impact on patient outcomes and CDI metrics are largely unknown.

Methods

This was a pre-post study at the University of Maryland Medical Center, evaluating the impact of a CDI testing strategy (introduced October 2018) that simultaneously reported NAAT and confirmatory enzyme immunoassay (EIA) when used with existing best practice alerts for appropriate testing. Pre-intervention (November 2017–September 2018) and post intervention (October 2018–March 2019) periods were compared for mean CDI incidence (CDI per 10,000 admissions) defined by: (1) positive NAAT, (2) reported CDI (last positive test), and (3) treated CDI (receiving oral vancomycin). Both community and hospital-onset cases were included. The NAAT CDI incidence was used as the pre-intervention comparison for all 3 measures. In addition, oral vancomycin days of therapy (DOT) per 1,000 patient-days (PD) was compared. Pre–post comparisons of mean CDI incidence and mean DOT rates were done using Student t-test.

Results

There were 3,237 samples tested (2,269 pre and 968 post-intervention) with 376 NAAT positive (262 pre and 114 post-intervention). Of the 99 tests with reflex EIA, there were 74 discordant tests (NAAT +/EIA -) with 35 (47%) treated for CDI. Mean NAAT CDI incidence pre-intervention was 54 per 10,000 admissions. Post-intervention mean CDI incidence decreased as follows: 45 NAAT CDI per 10,000 admissions (P = 0.13), 15 reported CDI per 1000 admissions (P < 0.0001), and 28 treated CDI per 10,000 admissions (P = 0.0007). Oral vancomycin DOT per 1,000 PD decreased from 16 to 9 (P = 0.0002).

Conclusion

C. difficile NAAT testing with confirmatory EIA, in combination with best practice alert, decreased reported and treated cases of CDI, which may distinguish infection vs. colonization and avoid unnecessary treatment, beyond that achieved with alerts that improve appropriate patient selection for testing.

Disclosures

All authors: No reported disclosures.

2174. Comparison of the Verigene® and the ePlex® Blood Culture Identification Panels for Gram-Positive and Gram-Negative Bloodstream Infections

Background

Rapid diagnostic testing for the management of bloodstream infections has become paramount to improving patient outcomes. The primary objective of this study was to assess the differences between 2 FDA approved instruments.

Methods

Retrospective study from August 2018 to April 2019 at the University of Maryland Medical Center. One positive blood culture from each patient was tested using the Verigene® blood culture Gram-positive (BC-GP) or Gram-negative (BC-GN) panels based on the Gram stain and then analyzed using the ePlex® Blood Culture Identification (BCID) Gram-positive (BCID-GP) or Gram-negative (BCID-GN) research-use-only panels and compared with culture results.

Results

The study consisted of 140 positive blood culture bottles. 14 bottles were excluded for a total of 55 GN and 71 GP bottles. Of the 55 GN bottles, 3 had 2 GN rods for a total of 58 GNRs. BCID-GN missed 1 P. aeruginosa, 2 S. maltophilia, and 1 E. coli for a 93% (53/57) positive agreement. The BCID-GN does not detect A. junii and therefore it was excluded. BC-GN did not identify 1 K. pneumoniae with a 98% (47/48) positive agreement. BC-GN does not include the detection of S. maltophilia (4), Serratia (4), Morganella (1), and B. fragilis (1)and these were excluded in the BC-GN analysis. CTX-M was the only resistant marker detected and both panels identified it correctly. 5 samples using the BCID-GN also detected Pan Gram-Positive; 3 grew GP organisms, the other 2 only grew E. coli. Of the 71 GP bottles, 3 had two GP bacteria totaling 74 GPs. BCID-GP missed 1 S. aureus, 1 invalid, and called an E. faecalis that was not identified by the reference method for a 99% (72/73) positive agreement. BC-GP does not detect Micrococcus (6) or E. gallinarum (1) and missed 1 S. mitis/oralis for a 99% (66/67) positive agreement. 18 samples were positive for mecA detected by both panels. 4 samples were vanA/B positive; 1 by BCID-GP was sensitive to vancomycin and not detected by BC-GP. BCID-GP detected 1 sample as Pan Gram-negative although a GNR was not detected.

Conclusion

BothVerigene® and ePlex® GP and GN panels have a high percent positive agreement. Laboratories should take into consideration the epidemiology of their bloodstream infections when deciding on panels for the rapid detection of bloodstream infections.

Disclosures

All authors: No reported disclosures.

141. Use of Rapid Diagnostic Testing in Gram-negative Bloodstream Infections with and without Antimicrobial Stewardship

Background

Verigene Blood Culture Gram-Negative (VBC-GN) is a rapid diagnostic test (RDT) that can detect key GNs and resistance within hours from Gram-stain. Numerous studies have shown that RDTs in BSIs improve clinical outcomes, particularly with active antimicrobial stewardship (AMS) intervention. Little is known regarding outcomes in GN BSI without vs. with AMS intervention.

Methods

A retrospective three-part quasi-experimental study of adult patients with GN BSI from December 2014 to April 2018. VBC-GN was introduced September 2015 and AMS review was implemented October 2017. Antibiotics were appropriate if active in vitro against isolated GN. Optimal antibiotics were not overly broad, accounted for resistance, source of infection, and other infecting organisms. Comparisons were made using Chi-squared for nominal variables and Kaplan–Meier with log-rank for time to event analysis.

Results

In total, 772 patients met inclusion. The most common source was urinary (30.1%) and E. coli was the most common GN (37.9%). Infectious Disease consults increased with each group (50.6% vs. 67.9% vs. 81.8%, P < 0.001). More patients pre-RDT (37.36%) and RDT+AMS (35.6%) compared with RDT only (24.6%) were critically ill, P = 0.001. Optimal therapy was achieved in more patients in RDT-only (79%) and RDT+AMS (86%) groups compared with pre-RDT (66%), P < 0.001. More patients in the pre-RDT group (44.7%) were appropriately de-escalated compared with RDT only (31.6%) and RDT + AMS (38.7%), P = 0.026. Appropriate escalation occurred most often in the RDT-only group (39.3%) vs. pre-RDT (15.2%) and RDT + AMS (14.2%), P = 0.019. Median post-BSI length of stay (8.2 vs. 7.1 vs. 8.5 days, P = 0.226) and inpatient mortality (10.8% vs. 14.3% vs. 11.4%, P = 0.493) were similar.

Conclusion

With the implementation of VBC-GN RDT there was a significantly decreased time to optimal therapy, mainly based on necessary antibiotic escalation. Antibiotic de-escalation remained a challenge, even with active AMS review.

Disclosures

All authors: No reported disclosures.

1837. Considerations for a Targeted Approach to Contact Precautions for Patients with MRSA in Hospitals: A Multicenter Cohort Study to Identify High-Risk Patient Characteristics and Healthcare Personnel Interactions

Background

Healthcare personnel’s (HCP) gloves and gowns are frequently contaminated with antibiotic-resistant bacteria in the intensive care unit (ICU). Guidelines recommend contact precautions for patients with methicillin-resistant Staphylococcus aureus (MRSA); however, this approach remains controversial. This study aimed to identify which patients are more likely to transfer MRSA to HCP gloves or gowns and to identify HCP interactions more likely to lead to glove or gown contamination.

Methods

In a multicenter cohort study of MRSA colonized patients, we observed HCP–patient interactions and cultured HCP’s gloves and gowns before doffing. We also assessed the association between bacterial burden and contamination by sampling patients’ anterior nares, perianal area, chest, and arm.

Results

We enrolled 402 MRSA-colonized patients and observed 3,982 HCP interactions. MRSA contamination of HCP gloves and gown occurred in 14.3% and 5.9% of interactions, respectively. Contamination of either gloves or gown occurred in 16.2% of interactions. Occupational/physical therapists had the highest rates of contamination (OR: 6.96 [95% CI: 3.51–13.79]), followed by respiratory therapists (OR: 5.34 [95% CI: 3.04–9.39]) when compared with the “Other” category. Touching the patient was associated with higher contamination (OR: 2.59 [95% CI: 1.04–6.51]) when compared with touching nothing in the room. Touching only the environment was not associated with glove or gown contamination (OR: 1.13 [95% CI: 0.43, 3.00]) when compared with touching nothing. Touching the endotracheal tube (OR: 1.75 [95% CI: 1.38–2.19]), bedding (OR: 1.43 [95% CI: 1.20–1.70]) and bathing a patient (OR: 1.32 [95% CI: 1.01–1.75]) increased odds of contamination when compared with not having such contacts (Figures 1 and 2). We found an association between increasing bacterial burden in the patient’s nares, perianal area, and chest skin and glove or gown contamination.

Conclusion

Contamination of HCP gloves and gowns with MRSA occurs frequently when caring for ICU patients. We identified interactions that are high-risk for transmission. Hospitals may consider optimizing contact precautions by using less precautions for low-risk interactions and more precautions for high-risk interactions.

Disclosures

All Authors: No reported Disclosures.

2168. Comparison of Rapid Diagnostic Tests for Bloodstream Infections Using Desirability of Outcome Ranking Management of Antimicrobial Therapy (DOOR-MAT)

Background

Rapid diagnostic tests (RDTs) for bloodstream infection (BSIs) are increasingly common. Decisions regarding which RDT to implement remains a clinical challenge given the diversity of organisms and resistance mechanisms detected by different platforms. The desirability of Outcome Ranking Management of Antimicrobial Therapy (DOOR-MAT) has been proposed as a framework to compare RDT platforms but reports of clinical application are lacking. This study compared potential antibiotic decisions based on results of two different RDTs for BSI using DOOR-MAT.

Methods

Retrospective study at University of Maryland Medical Center from August 2018 to April 2019 comparing Verigene® BC (VBC) to GenMark Dx ePlex® BCID for clinical blood cultures. VBC was part of standard of care, ePlex was run on discarded fresh or frozen blood samples. In this theoretical analysis, RDT result and local susceptibility data were applied by two Infectious Diseases pharmacists to make decisions regarding antibiotic selection in a blinded manner. Cohen’s Kappa statistic summarized overall agreement. DOOR-MAT, a partial credit scoring system, was applied to decisions based on final organism/susceptibility results (Figure 1). Scores were averaged between reviewers and mean scores compared between RDT systems using the t-test. Additionally, a sensitivity analysis with varied point assignment among Gram-negatives (AmpC-producers) was conducted.

Results

110 clinical isolates were included; 41 Gram-negative, 69 Gram-positive organisms. Overall agreement was 82% for VBC and 83% for ePlex. The average score for VBC was 86.1 (SD 31.3) compared with ePlex 92.9 (SD 22.9), P = 0.004. Among Gram-negatives, the average score for VBC was 79.9 (SD 32.1) compared with ePlex 88.1 (SD 28.8), P = 0.032. Among GPs the average score for VBC was 89.9 (SD 30.4) compared with ePlex 95.8 (SD 18.3), P = 0.048. Sensitivity analysis demonstrated an average score for of 89.9 (SD 30.4) for VBC compared with 95.8 (SD 18.3) for ePlex, P = 0.27.

Conclusion

The use of a partial credit scoring system such as the DOOR-MAT allows for comparisons between RDT systems beyond sensitivity and specificity allowing for enhanced clinical interpretation. In this theoretical comparison, the Genmark ePlex BCID scored higher among both GP and GN organisms.

Disclosures

All authors: No reported disclosures.

563. Association Between Chlorhexidine Gluconate Concentrations and Resistant Bacterial Bioburden on Skin

Background

Little research exists to guide optimal Chlorhexidine gluconate (CHG) bathing practices. We examined the association between CHG concentrations and methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Enterobacteriaceae (CRE), and vancomycin-resistant Enterococcus (VRE) on the skin. Also, we studied whether bioburden is affected by bathing method (2% CHG cloth vs. 4% liquid CHG soap) and time since last CHG bath.

Methods

Patients with MRSA, CRE and VRE at 4 US hospitals were enrolled. Skin swabs (arm, chest) were collected to quantify bioburden and CHG concentrations. Information on bathing method and time since last CHG bath was collected. χ ² test, Spearman’s correlation, and linear regression were performed.

Results

253 patients were enrolled. On arm skin, MRSA was detected in 17 (19%), CRE on 16 (12%), and VRE on 12 (21%) patients. Detectable CHG levels were observed in 82 (93%) MRSA, 81 (79%) CRE, and 44 (79%) VRE patients. A negative correlation was observed between bioburden and CHG concentration for MRSA (r_s = −0.11, P = 0.28) and CRE (r_s = −0.02, P = 0.82) while a positive correlation was observed for VRE (r_s = 0.15, P = 0.28). On chest skin, MRSA was detected in 25 (28%), CRE on 18 (12%), and VRE on 7 (13%) patients. Detectable CHG levels were observed in 83 (95.4%) MRSA, 78 (72%) CRE, and 43 (77%) VRE patients. MRSA bioburden was negatively correlated with CHG concentration (r_s = −0.16, P = 0.12), while a positive correlation was noted for CRE (r_s = 0.18, P = 0.06) and VRE (r_s =0.24, P = 0.06). There was no significant difference in bacterial bioburden between CHG concentrations (>20 ppm vs. ≤20 ppm) at both skin sites (Table 1). The bioburden did not differ by method of CHG bath. The mean estimates of bacterial bioburden on both skin sites did not show a significant decrease with increase in CHG concentrations and were not affected by time since last bath (Table 2).

Conclusion

Detection of MRSA, CRE and VRE was infrequent irrespective of CHG bathing method and time since last bath. We found inconsistent associations between increasing CHG concentrations and bacterial bioburden. CHG bathing frequency may be optimized for individual patient populations to augment the reduction of bacteria. Additional research to understand the association of CHG skin concentrations and resistant bacterial burden is required.

Disclosures

All authors: No reported disclosures.

Bacterial burden is associated with increased transmission to health care workers from patients colonized with vancomycin-resistant Enterococcus

BACKGROUND

Health care workers (HCWs) are significant vectors for transmission of multidrug-resistant organisms among patients in intensive care units (ICUs). We studied ICU patients on contact precautions, colonized with vancomycin-resistant Enterococcus (VRE), to assess whether bacterial burden is associated with transmission to HCWs' gloves or gowns, a surrogate outcome for transmission to subsequent patients.

METHODS

From this prospective cohort study, we analyzed 96 VRE-colonized ICU patients and 5 HCWs per patient. We obtained samples from patients' perianal area, skin, and stool to assess bacterial burden and cultured HCWs' gloves and gowns for VRE after patient care.

RESULTS

Seventy-one of 479 (15%) HCW-patient interactions led to contamination of HCWs' gloves or gowns with VRE. HCW contamination was associated with VRE burden on the perianal swab (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.19, 1.57), skin swabs (OR, 2.14; 95% CI, 1.51, 3.02), and in stool (OR, 1.95; 95% CI, 1.39, 2.72). Compared with colonization with Enterococcus faecalis, colonization with Enterococcus faecium was associated with higher bacterial burden and higher odds of transmission to HCWs.

CONCLUSIONS

We show that ICU patients with higher bacterial burden are more likely to transmit VRE to HCWs. These findings have implications for VRE decolonization and other infection control interventions.

Rapid Diagnostics for Blood Cultures: Supporting Decisions for Antimicrobial Therapy and Value-Based Care

Bacteremia and sepsis are critically important syndromes with high mortality, morbidity, and associated costs. Bloodstream infections and sepsis are among the top causes of mortality in the US, with >600 deaths each day. Most septic patients can be found in emergency medicine departments or critical care units, settings in which rapid administration of targeted antibiotic therapy can reduce mortality. Unfortunately, routine blood cultures are not rapid enough to aid in the decision of therapeutic intervention at the onset of bacteremia. As a result, empiric, broad-spectrum treatment is common-a costly approach that may fail to target the correct microbe effectively, may inadvertently harm patients via antimicrobial toxicity, and may contribute to the evolution of drug-resistant microbes. To overcome these challenges, laboratorians must understand the complexity of diagnosing and treating septic patients, focus on creating algorithms that rapidly support decisions for targeted antibiotic therapy, and synergize with existing emergency department and critical care clinical practices put forth in the Surviving Sepsis Guidelines.

1729. Effect of Glove Disinfection on Bacterial Contamination of Healthcare Worker Hands

Background

Disinfection of gloves and gowns was recommended to decrease healthcare worker (HCW) self-contamination during doffing of gloves and gowns in the Ebola epidemic. To understand the potential role of this practice in preventing bacterial transmission, we examined the effect of disinfectants on bacterial contamination of HCW hands following glove removal.

Methods

A laboratory simulation study was conducted using methicillin-susceptible Staphylococcus aureus and antibiotic-sensitive Klebsiella pneumoniae among volunteer HCWs (n = 10 per organism). For each experiment, the volunteer donned 2 pairs of gloves with the “under glove” simulating HCW hands and “top glove” simulating actual glove use in the clinical setting. The top-glove was inoculated with 10⁸ CFU bacteria for each step. Top gloves were sampled directly after inoculation (Arm A), and after disinfection with alcohol gel, bleach wipes, and quaternary ammonium (quat) wipes, in separate steps (Arm B). Under gloves were sampled after top glove removal without disinfection (Arm C), and top glove removal post disinfection (Arm D). Quantitative bacterial load reduction was compared for glove use (Arm C − Arm A), and for disinfectant use in addition to glove use (Arm D − Arm C). Qualitative detection of any bacterial load (present/absent) on under glove in the setting of disinfection prior to top glove removal was also assessed.

Results

Of 10⁸ CFU inoculated, the median recovery was 1.2 × 10⁴ CFU (both bacteria combined). After glove removal (no disinfection), the median recovery from the under glove was 2.7 × 10² CFU, for a reduction of 98% (1.6 log) in bacterial load. After top glove disinfection and removal, the median bacterial recovery from the under glove was 1.4 × 10², 0, and 0 CFU for alcohol, quat, and bleach (47% or 0.3 log reduction for alcohol; 99% or 2 log reduction for quat and bleach) (Figure 1). Regardless of quantity, bacteria were recovered from under gloves even after top glove disinfection in 70%, 40%, and 35% cases for alcohol, quat, and bleach, respectively (Figure 2).

Conclusion

Glove disinfection prior to glove removal is effective at reducing bacterial contamination of HCW hands. However, despite disinfection, some level of hand contamination occurs frequently.

Disclosures

J. K. Johnson, Q-Linea: Investigator, Research grant. Applied Biocode: Investigator, Research grant

451. High-Frequency of Multi-Drug-Resistant Organisms (MDRO) at University Teaching Hospital (UTH), Lusaka, Zambia

Background

Methods

Results

Conclusion

Disclosures

Validation of an Antimicrobial Stewardship-Driven Verigene Blood-Culture Gram-Negative Treatment Algorithm to Improve Appropriateness of Antibiotics

Rapid diagnostic testing (RDT) allows for early adjustment of antibiotic therapy. This study examined the potential impact of a stewardship-driven antibiotic treatment algorithm, incorporating RDT into the management of Gram-negative bacteremia. The proposed algorithm would have resulted in 88.4% of cases receiving appropriate antibiotic therapy versus 78.1% by standard of care (P = .014).

The Use of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for the Identification of Pathogens Causing Sepsis

BACKGROUND

Sepsis is a life-threatening condition with high rates of morbidity and mortality; effective and appropriate antibiotic therapy is essential for ensuring patient improvement. To aid in the diagnosis of sepsis, blood cultures are drawn and sent to the microbiology laboratory for pathogen growth, identification, and susceptibility testing. The clinical microbiology laboratory can assist the medical team by providing timely identification of the pathogen(s) causing the bloodstream infection through the use of rapid diagnostic technology. One of these rapid diagnostic technologies, MALDI-TOF MS, has been proven to reduce the time required for appropriate antibiotic therapy when used to identify pathogens grown in culture. This technology has also been used to identify pathogens directly from the positive blood cultures with great success.

CONTENT

In this minireview, we summarize the different methods that have been developed to directly identify pathogens from positive blood cultures by use of MALDI-TOF MS and the effect of this technology on patient outcomes. Additionally, we touch on current research in the field, including the identification of antimicrobial resistance directly from positive blood cultures by MALDI-TOF MS.

SUMMARY

Rapid identification of pathogens is important in the survival of patients undergoing a septic event. MALDI-TOF MS technology has played an important role in rapid identification, which has led to a reduction in the time to appropriate antibiotic therapy and contributed to the improvement of patient outcomes. The high sensitivity and specificity of MALDI-TOF MS identification, in combination with MALDI-TOF's rapid function and reduced labor costs, make this technology an attractive choice for clinical laboratories.

Comparison of Two Glove-Sampling Methods to Discriminate Between Study Arms of a Hand Hygiene and Glove-Use Study

In the absence of a gold standard, we compared two glove-sampling methodologies, direct imprint and the sponge stick, to detect a difference between two arms in our study relative to total amount and presence of bacteria.