Beta-lactam antibiotics administration among adult inpatients with a beta-lactam allergy label: incidence, predictors, and outcomes

Background

A beta-lactam antibiotics (BLA) allergy label is common, resulting in disadvantageous outcomes due to the usage of second-line antimicrobial agents. Noncontrolled case-series analyses report low rates of hypersensitivity reactions, following intentional/non-intentional BLA challenges among labeled inpatients. The study aims were to explore predictors and outcomes associated with hypersensitivity reactions following BLA challenge among BLA-allergic labeled inpatients.

Methods

Retrospective cohort study (2019-2020) of adult (≥18 years) inpatients (Shamir Medical Center, Israel), labeled as allergic to ≥1 BLA, who received ≥1 dose/s of BLA during their stay. Independent predictors to develop allergic reactions and the independent associations of allergic reactions with clinical outcomes were queried by logistic and Cox regressions.

Results

Of 9,670 inpatients (14,088 hospitalizations), 3,570 (37%) were labeled as allergic to ≥1 BLA. Of those, 1,171 (33%) patients received ≥1 BLA. The majority were women (67%), and the mean age was 69.3 ± 19.4 years. Only 30 patients (2.6%) developed a reaction, all mild. Independent predictors to develop an allergic reaction were documented reactions in the past, atopic background, antihistamines administration prior to the BLA challenge, and high risk for cross-reactivity, based on the BLA side chains, between the labeled and the challenged agents. Reaction upon the BLA challenge was not independently associated with any worse outcome.

Conclusions

Despite the commonality of allergy labeling, and the commonality of BLA administration to labeled inpatients, hypersensitivity reactions were mild and rare. Interventional stewardship strategies for active BLA de-labeling among low-risk patients should be promoted, to improve patients' and institutional health and fiscal outcomes.

The epidemiology of Stenotrophomonas maltophilia and Achromobacter xylosoxidans infections

Stenotrophomonas maltophilia and Achromobacter xylosoxidans are emerging nosocomial, non-glucose fermenting, Gram-negative pathogens. In this nested case-control trial, independent predictors for S. maltophilia infections were hemodialysis and recent antibiotic usage (overall), while recent usage of fluoroquinolones, was independently associated with A. xylosoxidans infections. Infections were independently associated with multiple worse outcomes.

Genomic analysis of the international high-risk clonal lineage Klebsiella pneumoniae sequence type 395

BACKGROUND

Klebsiella pneumoniae, which is frequently associated with hospital- and community-acquired infections, contains multidrug-resistant (MDR), hypervirulent (hv), non-MDR/non-hv as well as convergent representatives. It is known that mostly international high-risk clonal lineages including sequence types (ST) 11, 147, 258, and 307 drive their global spread. ST395, which was first reported in the context of a carbapenemase-associated outbreak in France in 2010, is a less well-characterized, yet emerging clonal lineage.

METHODS

We computationally analyzed a large collection of K. pneumoniae ST395 genomes (n = 297) both sequenced in this study and reported previously. By applying multiple bioinformatics tools, we investigated the core-genome phylogeny and evolution of ST395 as well as distribution of accessory genome elements associated with antibiotic resistance and virulence features.

RESULTS

Clustering of the core-SNP alignment revealed four major clades with eight smaller subclades. The subclades likely evolved through large chromosomal recombination, which involved different K. pneumoniae donors and affected, inter alia, capsule and lipopolysaccharide antigen biosynthesis regions. Most genomes contained acquired resistance genes to extended-spectrum cephalosporins, carbapenems, and other antibiotic classes carried by multiple plasmid types, and many were positive for hypervirulence markers, including the siderophore aerobactin. The detection of "hybrid" resistance and virulence plasmids suggests the occurrence of the convergent ST395 pathotype.

CONCLUSIONS

To the best of our knowledge, this is the first study that investigated a large international collection of K. pneumoniae ST395 genomes and elucidated phylogenetics and detailed genomic characteristics of this emerging high-risk clonal lineage.

The impact of bedside wipes in multi-patient rooms: a prospective, crossover trial evaluating infections and survival

BACKGROUND

Multidrug-resistant organisms (MDROs) are prevalent on high-touch surfaces in multi-patient rooms.

AIM

To quantify the impact of hanging single-use cleaning/disinfecting wipes next to each bed. Pre-specified outcomes were: (1) hospital-acquired infections (HAIs), (2) cleaning frequency, (3) MDRO room contamination, (4) new MDRO acquisitions, and (5) mortality.

METHODS

Clustered randomized crossover trial at Shamir Medical Center, Israel (October 2016 to January 2018). Clusters were randomly assigned to use for cleaning either single-use quaternary ammonium wipes (Clinell) or standard practices (reusable cloths and buckets with bleach). Six-month intervention periods were implemented in alternating sequence, separated by a washout period. Five high-touch surfaces were monitored by fluorescent markers. Study outcomes were compared between periods using generalized estimating equations, Poisson regression, and Cox proportional hazards models.

FINDINGS

Overall, 7725 patients were included (47,670 person-days), 3793 patients in rooms with intervention cleaning and 3932 patients in rooms with standard practices. During the intervention, there was no significant difference in HAI rates (incidence rate ratio: 1.6; 95% confidence interval (CI): 0.7-3.5; P = 0.3). However, in intervention rooms, the frequency of environmental cleaning was higher (odds ratio: 3.73; 95% CI: 2.0-7.1; P < 0.0001), MDRO environmental contamination rate was insignificantly lower (odds ratio: 0.7; 95% CI: 0.5-1.0; P = 0.06), new MDRO acquisition rate was lower (hazard ratio: 0.4; 95% CI: 0.2-1.0; P = 0.04), and in-hospital mortality rate was lower (incidence rate ratio: 0.8; 95% CI: 0.7-1.0; P = 0.03).

CONCLUSION

Hanging single-use cleaning/disinfecting wipes next to each bed did not affect the HAI rates but did improve the frequency of cleaning, reduce MDRO environmental contamination, and was associated with reduced incidence of new MDRO acquisitions and reduced mortality. This is a feasible, recommended practice to improve patient outcomes in multi-patient rooms.

Prolonged stay at an acute-care hospital in Israel among older adults awaiting transfer to post-acute care: retrospective study on risk factors and consequences

BACKGROUND

Older adults frequently experience deconditioning following acute illnesses and require discharge from acute-care facilities to post-acute care facilities, which are limited. Our study aimed to explore predictors and outcomes associated with elongated length of stay (LOS) among older adults awaiting discharge to skilled nursing facility (SNF).

METHODS

Retrospective cohort study was conducted at Shamir Medical Center, Israel, among adults (> 65 years) eligible for SNF. ROC curve analysis was used to determine prolonged LOS based on the risk to fall. Logistic and Cox regressions were used to analyze predictors and outcomes.

RESULTS

Among 659 older adults awaiting transfer to SNF, 127 patients (24% among survivors of the index hospitalization) had prolonged LOS (> 12 days). The median age of patients was 82 years and 51% were females. The independent predictors for prolonged LOS were lower Norton index, higher MUST score, and admission from home. Prolonged LOS was independently associated with hospital-acquired infections, device related infections, and acquisitions of multidrug-resistant organisms.

CONCLUSION

Prolonged LOS among older adults, awaiting transfer to SNF, should be suspected among non-institutionalized older adults with lower nutritional status and higher risk of pressure ulcers. The burden associated with establishing additional SNF beds, must be outweighed vs. the substantial infectious complications among awaiting older adults.

Colistin Monotherapy versus Combination Therapy for Carbapenem-Resistant Organisms

BACKGROUND

Pneumonia and bloodstream infections (BSI) due to extensively drug-resistant (XDR) Acinetobacter baumannii, XDR Pseudomonas aeruginosa, and carbapenem-resistant Enterobacterales (CRE) are associated with high mortality rates, and therapeutic options remain limited. This trial assessed whether combination therapy with colistin and meropenem was superior to colistin monotherapy for the treatment of these infections.

METHODS

The OVERCOME (Colistin Monotherapy versus Combination Therapy) trial was an international, randomized, double-blind, placebo-controlled trial. We randomly assigned participants to receive colistin (5 mg/kg once followed by 1.67 mg/kg every 8 hours) in combination with either meropenem (1000 mg every 8 hours) or matching placebo for the treatment of pneumonia and/or BSI caused by XDR A. baumannii, XDR P. aeruginosa, or CRE. The primary outcome was 28-day mortality, and secondary outcomes included clinical failure and microbiologic cure.

RESULTS

Between 2012 and 2020, a total of 464 participants were randomly assigned to treatment, and 423 eligible patients comprised the modified intention-to-treat population. A. baumannii was the predominant trial pathogen (78%) and pneumonia the most common index infection (70%). Most patients were in the intensive care unit at the time of enrollment (69%). There was no difference in mortality (43 vs. 37%; P=0.17), clinical failure (65 vs. 58%; difference, 6.8 percentage points; 95% confidence interval [CI], -3.1 to 16.6), microbiologic cure (65 vs. 60%; difference, 4.8 percentage points; 95% CI, -5.6 to 15.2), or adverse events (acute kidney injury, 52 vs. 49% [P=0.55]; hypersensitivity reaction, 1 vs. 3% [P=0.22]; and neurotoxicity, 5 vs. 2% [P=0.29]) between patients receiving monotherapy and combination therapy, respectively.

CONCLUSIONS

Combination therapy with colistin and meropenem was not superior to colistin monotherapy for the treatment of pneumonia or BSI caused by these pathogens. (Funded by the National Institute of Allergy and Infectious Diseases, Division of Microbiology and Infectious Diseases protocol 10-0065; ClinicalTrials.gov number, NCT01597973.).

The Epidemiology of Multidrug-Resistant Sepsis among Chronic Hemodialysis Patients

Sepsis is one of the leading causes of hospitalization and death among hemodialysis patients. Infections due to multidrug-resistant organisms (MDROs) are common among these patients, but empiric broad-spectrum coverage for every septic patient is associated with unfavorable outcomes. A retrospective case–control study was conducted at Shamir Medical Center, Israel (July 2016–April 2020), to determine predictors of MDRO infections among septic (per SEPSIS-3) ambulatory adult hemodialysis patients with permanent dialysis access (i.e., fistula, graft, or tunneled Perm-A-Cath). MDROs were determined according to established definitions. Least Absolute Shrinkage and Selection Operator (LASSO) regression was used to construct a prediction score and determine its performance. Of 509 patients, 225 (44%) had microbiologically confirmed infection, and 79 patients (35% of 225) had MDROs. The eventual independent predictors of MDRO infections were Perm-A-Cath access (vs. fistula or graft, aOR = 3, CI-95% = 2.1–4.2) and recent hospitalization in the previous three months (aOR = 2.3, CI-95% = 1.6–3.3). The score to predict MDRO sepsis with the highest performances contained seven parameters and displayed an area under the receiver operating characteristic curve (ROC AUC) of 0.74. This study could aid in defining a group of hemodialysis patients for which empiric broad-spectrum agents could be safely avoided.

Empiric Usage of “Anti-Pseudomonal” Agents for Hospital-Acquired Urinary Tract Infections

Hospital-acquired urinary tract infection (HAUTI) is one of the most common hospital-acquired infections, and over 80% of HAUTI are catheter-associated (CAUTI). Pseudomonas aeruginosa, as well as other non-glucose fermenting Gram negative organisms (NGFGN, e.g., Acinetobacter baumannii), are frequently covered empirically with “anti-Pseudomonals” being administered for every HAUTI (and CAUTI). However, this common practice was never trialed in controlled settings in order to quantify its efficacy and its potential impacts on hospitalization outcomes. There were 413 patients with HAUTI that were included in this retrospective cohort study (2017–2018), 239 (57.9%) had CAUTI. There were 75 NGFGN infections (18.2% of HAUTI, 22.3% of CAUTI). P. aeruginosa was the most common NGFGN (82%). Despite multiple associations per univariable analysis, recent (3 months) exposure to antibiotics was the only independent predictor for NGFGN HAUTI (OR = 2.4, CI-95% = 1.2–4.8). Patients who received empiric anti-Pseudomonals suffered from worse outcomes, but in multivariable models (one for each outcome), none were independently associated with the empiric administration of anti-Pseudomonals. To conclude, approximately one of every five HAUTI (and CAUTI) are due to NGFGN, which justifies the practice of empiric anti-Pseudomonals for patients with HAUTI (and CAUTI), particularly patients who recently received antibiotics. The practice is not associated with independent deleterious impacts on outcomes.

630. Emergence of Colistin Resistance in the OVERCOME Trial: Impact of Combination Therapy with Meropenem

Background

Colistin (COL) remains an important therapeutic option for carbapenem-resistant (CR) Gram-negative bacilli (GNB). COL is often utilized in combination with meropenem (MEM), in part due to concerns regarding the development of COL resistance with monotherapy. We recently completed a randomized controlled trial comparing outcomes in patients receiving COL + placebo to those receiving COL + MEM; herein we present data on the emergence of COL resistance in this trial.

Methods

OVERCOME was an international, multicenter, randomized, double-blind, placebo-controlled study comparing COL and COL + MEM for the treatment of bloodstream infection and/or pneumonia due to CR GNB. Subjects were included in the modified intent to treat population (mITT) if their enrollment pathogen had a COL MIC ≤2 mg/L, as determined by broth microdilution (BMD). Daily blood and/or respiratory samples were obtained in patients per protocol until two consecutive negatives were obtained or the end of study treatment. All subsequent isolates were evaluated for COL resistance via BMD, defined as MIC ≥ 4 mg/L.

Results

Of the 425 patients in the mITT population, 380 (191 COL; 189 COL + MEM) were evaluable for the endpoint of COL resistance development. The median age of the cohort was 70, 38% were female, 47% were white, and 45% were Asian. 70% had an index infection of pneumonia, 68% were in the intensive care unit at the onset of their infection, and A. baumannii was the most common pathogen (78% of patients). Baseline characteristics, infection type, severity of illness, and index pathogen were similar amongst treatment arms. No significant difference in resistance development was seen between the COL and COL + MEM groups overall (12% vs. 8%; p = 0.31), or in any subgroup (Table). In patients with A. baumannii, there was a trend towards decreased resistance development with COL + MEM (13.3% vs 7.5%; p = 0.13).

Conclusion

We were unable to identify a significant difference in resistance emergence between treatment arms, but given the low incidence of this outcome, were underpowered to do so. The impact of COL + MEM on preventing emergence of COL resistance in A. baumannii warrants further clinical study.

Disclosures

Jason M Pogue, PharmD, BCPS, BCIDP, Merck (Consultant)QPex (Consultant)Shionogi (Consultant)Utility Therapeutics (Consultant)VenatoRX (Consultant) Michael J. Rybak, PharmD, MPH, PhD, Paratek Pharmaceuticals (Research Grant or Support) Emmanuel Roilides, MD, PhD, FIDSA, FAAM, FESCMID, Merck Sharp & Dohme Corp. (Consultant, Grant/Research Support) Matthew Sims, MD, PhD, Astra Zeneca (Independent Contractor)Diasorin Molecular (Independent Contractor)Epigenomics Inc (Independent Contractor)Finch (Independent Contractor)Genentech (Independent Contractor)Janssen Pharmaceuticals NV (Independent Contractor)Kinevant Sciences gmBH (Independent Contractor)Leonard-Meron Biosciences (Independent Contractor)Merck and Co (Independent Contractor)OpGen (Independent Contractor)Prenosis (Independent Contractor)Regeneron Pharmaceuticals Inc (Independent Contractor)Seres Therapeutics Inc (Independent Contractor)Shire (Independent Contractor)Summit Therapeutics (Independent Contractor)

638. The Impact of in vitro Synergy Between Colistin and Meropenem on Clinical Outcomes in Invasive Carbapenem-resistant Gram-negative Infections: A Report from the OVERCOME Trial

Background

Consensus guidelines caution against colistin (COL) monotherapy due to efficacy and resistance development concerns. The COL + meropenem (MEM) combination often displays in vitro synergy against carbapenem-resistant (CR) Gram-negative bacilli (GNB). We recently completed a clinical trial comparing outcomes in patients receiving COL vs. COL + MEM. Herein we assess if, amongst patients receiving COL + MEM, outcomes differed as a function of the presence (or absence) of in vitro synergy against the index pathogen.

Methods

OVERCOME was an international, multicenter, randomized, double-blind, placebo-controlled study comparing COL + placebo and COL + MEM for the treatment of pneumonia and/or bloodstream infection (BSI) due to CR GNB. Baseline isolates were COL susceptible (MIC ≤ 2 mg/L) and underwent synergy testing to COL + MEM in 24-hour time kill experiments (TKE). Synergy was defined as a &gt;2-log CFU/ml reduction with combination therapy compared to the most active single agent. Outcomes assessed included 28-day mortality, clinical failure, and the development of COL resistance (MIC ≥ 4 mg/L) for both the overall cohort and the subgroup with A. baumannii.

Results

Of the 211 patients who received COL + MEM in OVERCOME, 186 had baseline synergy testing performed and were eligible for this analysis. The median age of the cohort was 70 years, 35% were female, 48% were white, and 44% Asian. Sixty-eight percent were in the intensive care unit (ICU) at infection onset. A. baumannii was the most common pathogen (78%) and pneumonia was the most common infection (68%). Synergy was demonstrated in most isolates (76%). Baseline characteristics, clinical, and microbiological outcomes were similar amongst patients infected with isolates against which COL + MEM demonstrated synergy and those where no synergy was demonstrated (Table 1). In patients with A. baumannii infections, the presence of in vitro synergy was associated with a decrease in clinical failure (53% vs. 79%; p = 0.04). No significant impact of synergy on 28-day mortality or development of COL resistance was demonstrated (Table 2).

Conclusion

The presence of in vitro synergy via TKE was associated with a decrease in clinical failure in patients treated with COL + MEM for invasive infections due to CR A. baumannii.

Disclosures

Jason M Pogue, PharmD, BCPS, BCIDP, Merck (Consultant)QPex (Consultant)Shionogi (Consultant)Utility Therapeutics (Consultant)VenatoRX (Consultant) Michael J. Rybak, PharmD, MPH, PhD, Paratek Pharmaceuticals (Research Grant or Support) Emmanuel Roilides, MD, PhD, FIDSA, FAAM, FESCMID, Merck Sharp & Dohme Corp. (Consultant, Grant/Research Support) Matthew Sims, MD, PhD, Astra Zeneca (Independent Contractor)Diasorin Molecular (Independent Contractor)Epigenomics Inc (Independent Contractor)Finch (Independent Contractor)Genentech (Independent Contractor)Janssen Pharmaceuticals NV (Independent Contractor)Kinevant Sciences gmBH (Independent Contractor)Leonard-Meron Biosciences (Independent Contractor)Merck and Co (Independent Contractor)OpGen (Independent Contractor)Prenosis (Independent Contractor)Regeneron Pharmaceuticals Inc (Independent Contractor)Seres Therapeutics Inc (Independent Contractor)Shire (Independent Contractor)Summit Therapeutics (Independent Contractor)

Multidrug-Resistant Gram-Negative Bacteria: Infection Prevention and Control Update

Multidrug-resistant gram-negative bacteria (MDR-GNB) pose one of the greatest challenges to health care today because of their propensity for human-to-human transmission and lack of therapeutic options. Containing the spread of MDR-GNB is challenging, and the application of multifaceted infection control bundles during an evolving outbreak makes it difficult to measure the relative impact of each measure. This article will review the utility of various infection control measures in containing the spread of various MDR-GNB and will provide the supporting evidence for these interventions.

The Impact of Differences in Surveillance Definitions of Hospital Acquired Urinary Tract Infections (HAUTI)

Hospital-acquired urinary tract infections (HAUTI) are common and most cases are related to catheters (CAUTI). HAUTI and CAUTI surveillance is mandatory in many countries as a measure to reduce the incidence of infections and appropriately direct the allocation of preventable resources. The surveillance criteria issued by the Israeli Ministry of Health (IMOH), differ somewhat from that of the U.S. Centers for Disease Control and Prevention (CDC). Our study aims were to query and quantify the impact of these differences. In a retrospective cohort study conducted at Shamir Medical Center, for calendar year 2017, the surveillance criteria of both IMOH and CDC were applied on 644 patient-unique adults with “positive” urine cultures (per similar definitions). The incidence of HAUTI per IMOH was significantly higher compared to CDC (1.24/1000 vs. 1.02/1000 patient-days, p = 0.02), with no impact on hospitalization’s outcomes. The agreement rate between methods was high for CAUTI (92%), but much lower for all HAUTI (83%). The major error rate, i.e., patients diagnosed with HAUTI per IMOH but had no UTI per CDC, was 31%. To conclude, in order for surveillance to reflect the relative situation and direct allocation of preventable resources based on scientific literature, the process should be uniform worldwide.

Sero-Prevalence and Sero-Incidence of Antibodies to SARS-CoV-2 in Health Care Workers in Israel, Prior to Mass COVID-19 Vaccination

Objectives: This study aims to examine the prevalence and risk factors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sero-positivity in health care workers (HCWs), a main risk group, and assess the sero-incidence of SARS-CoV-2 infection between the first and second waves of coronavirus disease 2019 (COVID-19) in Israel. Methods: A longitudinal study was conducted among 874 HCWs from nine hospitals. Demographics, health information, and blood samples were obtained at baseline (first wave-April-May 2020) and at follow-up (n = 373) (second wave-September-November 2020). Sero-positivity was determined based on the detection of total antibodies to the nucleocapsid antigen of SARS-CoV-2, using electro-chemiluminescence immunoassay (Elecsys® Anti-SARS-CoV-2, Roche Diagnostics, Rotkreuz, Switzerland). Results: The sero-prevalence of SARS-CoV-2 antibodies was 1.1% [95% confidence intervals (CI) 0.6-2.1] at baseline and 8.3% (95% CI 5.9-11.6) at follow-up. The sero-conversion of SARS-CoV-2 serum antibody was 6.9% (95% CI 4.7-9.9) during the study period. The increase in SARS-CoV-2 sero-prevalence paralleled the rise in PCR-confirmed SARS-CoV-2 infections among the HCWs across the country. The likelihood of SARS-CoV-2 sero-prevalence was higher in males vs. females [odds ratio (OR) 2.52 (95% CI 1.05-6.06)] and in nurses vs. physicians [OR 4.26 (95% CI 1.08-16.77)] and was associated with being quarantined due to exposure to COVID-19 patients [OR 3.54 (95% CI 1.58-7.89)] and having a positive PCR result [OR 109.5 (95% CI 23.88-502.12)]. Conclusions: A significant increase in the risk of SARS-CoV-2 infection was found among HCWs between the first and second waves of COVID-19 in Israel. Nonetheless, the sero-prevalence of SARS-CoV-2 antibodies remains low, similar to the general population. Our findings reinforce the rigorous infection control policy, including quarantine, and utilization of personal protective equipment that should be continued together with COVID-19 immunization in HCWs and the general population.

The association of diabetes and hyperglycemia with sepsis outcomes: a population-based cohort analysis

The independent association of diabetes and hyperglycemia on the outcomes of sepsis remains unclear. We conducted retrospective cohort analyses of outcomes among patients with community-onset sepsis admitted to Shamir Medical Center, Israel (08-12/2016). Statistical associations were queried by Cox and logistic regressions, controlled for by matched propensity score analyses. Among 1527 patients with community-onset sepsis, 469 (30.7%) were diabetic. Diabetic patients were significantly older, with advanced complexity of comorbidities, and were more often exposed to healthcare environments. Despite statistically significant univariable associations with in-hospital and 90-day mortality, the adjusted Hazard Ratios (aHR) were 1.21 95% CI 0.8-1.71, p = 0.29 and 1.13 95% CI 0.86-1.49, p = 0.37, respectively. However, hyperglycemia at admission (i.e., above 200 mg/dl (was independently associated with: increased in-hospital mortality, aHR 1.48 95% CI 1.02-2.16, p = 0.037, 30-day mortality, aHR 1.8 95% CI 1.12-2.58, p = 0.001), and 90-day mortality, aHR 1.68 95% CI 1.24-2.27, p = 0.001. This association was more robust among diabetic patients than those without diabetes. In this study, diabetes was not associated with worse clinical outcomes in community-onset sepsis. However, high glucose levels at sepsis onset are independently associated with a worse prognosis, particularly among diabetic patients. Future trials should explore whether glycemic control could impact the outcomes and should be part of the management of sepsis, among the general adult septic population.

The Continuing Plague of Extended-Spectrum β-Lactamase Producing Enterbacterales Infections: An Update

Antimicrobial resistance is a common iatrogenic complication of modern life and medical care. One of the most demonstrative examples is the exponential increase in the incidence of extended-spectrum β-lactamases (ESBLs) production among Enterobacteriaceae, that is, the most common human pathogens outside of the hospital setting. Infections resulting from ESBL-producing bacteria are associated with devastating outcomes, now affecting even previously healthy individuals. This poses an enormous burden and threat to public health. This article aims to narrate the evolving epidemiology of ESBL infections and highlights current challenges in terms of management and prevention of these common infections.

The Clinical and Molecular Epidemiology of Noncarbapenemase-Producing Carbapenem-Resistant Enterobacteriaceae: A Case-Case-Control Matched Analysis

Background

Risk factors and outcomes associated with carbapenem-resistant Enterobacteriaceae (CRE) acquisitions are derived primarily from cohorts consisting of carbapenemase-producing (CP) strains. Worldwide epidemiology of non-CP-CRE is evolving, but controlled epidemiological analyses are lacking.

Methods

A matched case-case-control investigation was conducted at Shamir (Assaf Harofeh) Medical Center, Israel, on November 2014–December 2016. Noncarbapenemase-producing CRE (as defined by the US Clinical and Laboratory Standards Institute Standards) carriers were matched to patients with non-CRE Enterobacterales and to uninfected controls (1:1:1 ratio). Matched and nonmatched multivariable regression models were constructed to analyze predictors for acquisition and the independent impact of carriage on multiple outcomes, respectively. Representative isolates were whole genome sequenced and analyzed for resistome and phylogeny.

Results

Noncarbapenemase-producing CRE carriers (n = 109) were matched to the 2 comparative groups (overall n = 327). Recent exposure to antibiotics (but not specifically to carbapenems), prior intensive care unit admission, and chronic skin ulcers were all independent predictors for non-CP-CRE acquisition. Acquisitions were almost exclusively associated with asymptomatic carriage (n = 104), and despite strong associations per univariable analyses, none were independently associated with worse outcomes. Genomic analyses of 13 representative isolates revealed polyclonality, confirmed the absence of carbapenemases, but confirmed the coexistence of multiple other genes contributing to carbapenem-resistance phenotype (multiple beta-lactamases and efflux pumps).

Conclusions

Noncarbapenemase-producing CRE acquisitions are primarily associated with asymptomatic carriage, specifically among prone populations with extensive recent exposures to antibiotics. The prevalent mode of acquisition is “emergence of resistance” (not “patient-to-patient transmission”), and therefore the role of stewardship interventions in reducing the spread of these therapeutically challenging pathogens should be further explored.

Potential impact of removing metronidazole from treatment armamentarium of mild acute Clostridioides difficile infection

Aim: Recent guidelines recommended removing metronidazole as a therapeutic option for Clostridioides difficile infections (CDI). However, superiority of vancomycin over metronidazole in mild CDI is not established and use of vancomycin might lead to emergence of vancomycin-resistant enterococci (VRE). Patients & methods: A retrospective cohort study and efficacy analyses were conducted at Shamir Medical Center, Israel (2010-2015), among adults with acute CDI. Results: A total of 409 patients were enrolled. In multivariable analyses, metronidazole was noninferior to vancomycin for mild CDI, but vancomycin was an independent predictor for post-CDI VRE acquisition. Conclusion: A significant independent association was evident between treatment with vancomycin and, later, acquisition of VRE. In first episodes of mild acute CDI, metronidazole should be considered a valid therapeutic option.

496. Carbapenem-resistant Enterobacter: A Case-Case–Control Investigation

Background. Background

The World Health Organization has declared carbapenem-resistant Enterobacteriaceae (CRE) as a worldwide public health threat. Analyzing the epidemiology of CRE was derived from cohorts consisting primarily of Klebsiella pneumoniae isolates. The second most frequent CRE is Enterobacter (CREn), but its molecular and clinical epidemiology differ from that of K. pneumoniae, and it has not been analyzed while implementing updated methodological tools and design.

Methods

A matched case-case–control investigation was conducted at Shamir (Assaf Harofeh) Medical Center, Israel, for calendar years 2007–2017. Each CREn case was matched to a carbapenem-susceptible Enterobacter (CSEn) case and to an uninfected control (1:1:1 ratio). Logistic and Cox regression-matched analyses were conducted in order to study predictors and outcomes of CREn colonization and/or infection, respectively.

Results

The study included 216 cases (72 in each group). Numerous predictors were significantly associated with CREn as per bivariable analyses, but the only independent significant predictors were: (1) recent (3 months) exposure to fluoroquinolones (aOR=2.94, P = 0.04), (2) intensive care unit stay in current hospitalization prior to culture (aOR=3.56, P = 0.003), and (3) a rapidly fatal McCabe score (aOR=0.471, P = 0.01). Patients with CREn suffered from significant delays in instituting appropriate antimicrobials (P = 0.03), and for those who survived the hospitalization, were more frequently discharged to a long-term care facility after being admitted to the index hospitalization from home (aOR=3.3, P = 0.02).

Conclusion

This case-case–control-matched investigation of CREn epidemiology, revealed a unique modifiable predictor, i.e., recent fluoroquinolone exposure, which could represent a target for stewardship intervention. The case-case–control-matched design allowed for the control of numerous confounders previously reported to be associated with CREn but may represent a risk factor for Enterobacter infection in general. As with other CRE, CREn carriers suffer from significant delays in initiation of appropriate antimicrobials and from worse outcomes.

Disclosures

All authors: No reported disclosures.

2043. The “Resistance Calculator”: Refining Empiric Practices of Antimicrobials Prescription in the Era of Widespread Resistance

Background

In the era of widespread resistance, there are two events in the course of a hospitalized septic patient where the majority of empiric prescription errors occur: (1) infections upon admission (UA) due to multi-drug-resistant organisms (MDRO) and (2) nosocomial infections due to extensively drug-resistant organisms (XDRO). These errors seriously impact patient outcomes and the ecological burden of resistance. Our objective was to develop a tool, to calculate the probability of MDRO UA, and nosocomial XDRO infections, in order to reduce delays in initiating appropriate therapy to the “right population,” i.e., with “resistant pathogens,” while avoiding overuse of broader (frequently more toxicת less efficacious) therapeutics to the “wrong population,” i.e., with “susceptible pathogens.”

Methods

Retrospective case–control analyses were conducted for septic adults at Shamir Medical Center, Israel (2016). Logistic regression was used to develop models of risk factors. All parameters incorporated into the models were readily accessible at the point of care. The performances of the development cohorts, and on 8 other validation cohorts, were assessed by the area under the receiver operating characteristic curve (ROC AUC). A web calculator (mobile modifiable) was generated.

Results

A total of 4,199 patients were enrolled: 2,472 with sepsis UA, and 1,727 with nosocomial sepsis. The “MDR UA score” included 10 parameters and with a cutoff of ≥22 points, had a ROC AUC of 0.85 (sensitivity 86%, NPV 98%). The “Nosocomial XDR score” included 7 parameters and with a cutoff of ≥36 points, had a ROC AUC of 0.88 (sensitivity 90%, NPV 96%). The median ROC AUC was 0.75 among the validation cohorts of the “MDR UA score,” and 0.66 among the “Nosocomial XDR score.” A free web tool was generated: https://assafharofe.azurewebsites.net/.

Conclusion

A simple electronic calculator was generated to aid in bedside empiric prescription practices. The tool is composed of two scores to assist in common scenarios where the majority of errors occur. Prospective interventional investigations, should trial the performances of this tool in improving patient outcomes and the ecological burden in the facility.

Disclosures

All authors: No reported disclosures.

Use of Colistin in Critically Ill Patients

Due to lack of better therapeutic options, colistin use for extensively drug-resistant Gram-negative organisms was revived in the past two decades, including in patients in intensive-care units (ICU). There are multiple knowledge gaps pertaining to the clinical use and utility of colistin in critically-ill patients, but due to lack of options, it is used in these high risk patients. In this chapter, we critically review the various topics pertaining to colistin use in critically-ill patients, while highlighting the (lack of) controlled evidence supporting common current practices pertaining to colistin use by clinicians.

1204. The MDR Upon Admission Score for Shortening Time to Initiation of Appropriate Antimicrobial Therapy in the Era of Widespread Resistance to Antimicrobials

Background

Multi-drug-resistant organisms (MDRO) pose a growing burden, including in non-hospital settings. Delay in initiation of appropriate antimicrobial therapy (DAAT) upon admission to an acute care hospital is common and is associated with worse outcomes. The aim of this study was to develop a prediction score for MDRO infection upon admission, in order to improve patients’ outcomes and avoid misuse of broad-spectrum antimicrobials.

Methods

A retrospective case–control analysis was conducted at Assaf Harofeh Medical Center, Israel, comparing adult patients with MDRO infections diagnosed in the first 48 hours of hospitalization to patients presenting with non-MDRO sepsis (i.e., patients with microbiologically confirmed non-MDRO infection, or patients with non-microbiologically confirmed sepsis). MDROs were determined by clinical laboratory testing. Patients were identified over four consecutive months (August–December 2016). A multivariable logistic regression of predictors for MDRO infection upon admission was used to develop the prediction score.

Results

Ninety-five of 818 total patients (11.6%) had MDRO infection. The final score included 10 parameters: (1) home therapy (IV therapy, wound care, or specialized nursing care, 16 points), (2) routine (at least weekly) outpatient clinic visits in the past 3 months (15 points), (3) history (2 years) of past MDRO colonization (14 points), (4) any antibiotics in the preceding 3 months (12 points), (5) invasive procedure in the past 6 months (11 points), (6) elderly (≥65 years old, 10 points), (7) hemiplegia or paraplegia (8 points), (8) resident of long-term care facility (7 points), (9) severe sepsis (i.e., severe sepsis, septic shock, or multi-organ failure, 6 points), and (10) acute kidney injury (5 points). A cutoff of ≥24 points had a sensitivity of 90%, a specificity of 73% and an ROC AUC = 0.88 (figure).

Conclusion

This study presents the development of a new prediction score for MDRO infection upon admission, based on parameters that could easily be extracted at bedside for patients admitted with sepsis. A future prospective interventional study is needed in order to validate the score, captured at bedside electronically, in terms of improving patients’ outcomes.

Disclosures

All authors: No reported disclosures.

1150. Cleaning High Touch Surfaces of Patients’ Rooms: Make It Easier, and It Simply Gets Cleaner

Background

The healthcare environment has been established as a reservoir for human pathogens and specifically multidrug-resistant organisms (MDRO). High touch surfaces and fomites in a patient’s room mediate transmission between infected and uninfected patients and personnel. Efforts to reduce hospital-associated infections due to MDROs often focus on room cleaning; however, adherence to and thoroughness of cleaning pose significant challenges.

Methods

A crossover trial was implemented in January 2016 (for 15 months) at Assaf Harofeh Medical Center (Israel) in four identical medical units. Single-use wipes (Clinell®; universal wipes and sporicidal wipes for rooms of patients with C. difficile), were compared with common practices which consisted of reusable cloths and bleach (1,000–5,000 ppm). Six-month cleaning and intervention periods were used on units in alternating sequences, separated by washout periods. Cleaning was monitored twice a week (bedrail, bedside table, clinical binder, call button, and lamp switch), by a fluorescent marker system (Clinell®). Comparisons used GEE with clustering for room. Staff were surveyed on intervention feasibility, acceptability, and satisfaction.

Results

Complete cleaning in all five test locations was found in 23% of 400 total assessments and was more common in the intervention group (34% vs. 12%; OR = 3.7; P < 0.001). Cleaning adherence was highest for the bed rail (71%) and lowest for the call button (38%). The use of wipes had the largest effect on adherence for the light switch (59% vs. 26%; OR = 4.2; P < 0.001). Intervention timing was not associated with overall adherence (P = 0.10). 94% of staff reported overall satisfaction of “very good” or “excellent,” and 90% of staff reported that use of the wipes shortened the cleaning process.

Conclusion

The use of cleaning wipes resulted in greater adherence to room cleaning and the method was reported to be acceptable to staff. Future aims of this large study (over 10,000 patients were enrolled and data collection not yet completed) are to determine the impact of this intervention on rates of hospital-acquired infections, MDRO acquisitions, and mortality.

Disclosures

E. T. Martin, Clinell: Grant Investigator, Research grant. D. Marchaim, Clinell: Grant Investigator, Grant recipient.

Towards a Definition for Health Care-Associated Infection

BACKGROUND

Health care-associated infection (HcAI) is a term frequently used to describe community-onset infections likely to be caused by multidrug-resistant organisms (MDROs). The most frequently used definition was developed at Duke University Medical Center in 2002 (Duke-2002). Although some professional societies have based management recommendations on Duke-2002 (or modifications thereof), neither Duke-2002 nor other variations have had their performance measured.

METHODS

A case-control study was conducted at Assaf Harofeh Medical Center (AHMC) of consecutive adult bloodstream infections (BSIs). A multivariable model was used to develop a prediction score for HcAI, measured by the presence of MDRO infection on admission. The performances of this new score and previously developed definitions at predicting MDRO infection on admission were measured.

RESULTS

Of the 504 BSI patients enrolled, 315 had a BSI on admission and 189 had a nosocomial BSI. Patients with MDRO-BSI on admission (n = 100) resembled patients with nosocomial infections (n = 189) in terms of epidemiological characteristics, illness acuity, and outcomes more than patients with non-MDRO-BSI on admission (n = 215). The performances of both the newly developed score and the Duke-2002 definition to predict MDRO infection on admission were suboptimal (area under the receiver operating characteric curve, 0.76 and 0.68, respectively).

CONCLUSIONS

Although the term HcAI is frequently used, its definition does not perform well at predicting MDRO infection present on admission to the hospital. A validated score that calculates the risk of MDRO infection on admission is still needed to guide daily practice and improve patient outcomes.

[THE EPIDEMIOLOGY OF CLOSTRIDIUM DIFFICILE INFECTIONS AND ASPECTS PERTAINING TO TREATMENT WITH VANCOMYCIN AT ASSAF HAROFEH MEDICAL CENTER]

BACKGROUND

The epidemiology of Clostridium difficile infections (CDI) have evolved dramatically in the past decade. Vancomycin is the treatment of choice for moderate to severe CDI. However, controlled comparative data pertaining to mild CDI is lacking. Furthermore, the potential impact of vancomycin treatment on subsequent vancomycin-resistant Enterococcus (VRE) isolation remains unknown.

METHODS

A retrospective cohort analysis was executed at the Assaf Harofeh Medical Center, from 2013 to 2015. Adult patients (>18 years) with a first episode of acute CDI, determined per pre-established criteria, were enrolled. The efficacy of vancomycin vs. metronidazole among patients with mild CDI, and the independent association of oral vancomycin treatment during the acute CDI and later (up to 18 months) VRE isolation, was analyzed by logistic regression.

RESULTS

A total of 260 patients with CDI were enrolled. The majority were elderly (75%), and 56% had moderate to severe disease. Among 75 patients with mild disease, no differences were observed in terms of clinical outcomes between vancomycin or metronidazole treatment. Metronidazole remained non-inferior even after incorporating a prediction score to control for confounders associated with being a "vancomycin case". In multivariable analysis, oral vancomycin treatment during the acute CDI was the strongest independent predictor for later isolation of VRE (aOR=74, p=0.004).

CONCLUSIONS

Our study suggests that metronidazole should remain the recommended treatment of choice for mild CDI, due to clinical non-inferiority and an apparent association between vancomycin therapy and subsequent VRE isolation on an individual patient level analysis.

Therapeutic Management of Pseudomonas aeruginosa Bloodstream Infection Non-Susceptible to Carbapenems but Susceptible to "Old" Cephalosporins and/or to Penicillins

It is unknown as to whether other beta-lactams can be used for bloodstream infections (BSI) resulting from Pseudomonas aeruginosa (PA) which are non-susceptible to one or more carbapenem. We conducted a retrospective cohort study at the Assaf Harofeh Medical Center (AHMC) from January 2010 to August 2014. Adult patients with PA-BSI non-susceptible to a group 2 carbapenem but susceptible to ceftazidime or piperacillin (with or without tazobactam), were enrolled. We compared the outcomes of patients who received an appropriate beta-lactam antibiotic (“cases”) to those who received an appropriate non-beta-lactam antibiotic (“controls”). Whole genome sequencing was performed for one of the isolates. Twenty-six patients with PA-BSI met inclusion criteria: 18 received a beta-lactam and 8 a non-beta-lactam (three a fluoroquinolone, two colistin, one a fluoroquinolone and an aminoglycoside, one a fluoroquinolone and colistin, and one colistin and an aminoglycoside). All clinical outcomes were similar between the groups. There were large variations in the phenotypic susceptibilities of the strains. A detailed molecular investigation of one isolate revealed a strain that belonged to MLST-137, with the presence of multiple efflux pumps, OXA-50, and a chromosomally mediated Pseudomonas-derived cephalosporinase (PDC). The oprD gene was intact. Non-carbapenem-β-lactams may still be effective alternatives for short duration therapy (up to 14 days) for BSI caused by a carbapenem non-susceptible (but susceptible to ceftazidime, piperacillin, and/or piperacillin-tazobactam) PA strain. This observation requires further confirmatory analyses. Future molecular investigations should be performed, in order to further analyze additional potential mechanisms for this prevalent phenotype.

Serum Procalcitonin as a Marker for Infection in Patients with Acute Myocardial Infarction

Background

Significant proportion of patients with acute myocardial infarction (AMI) also present with systemic inflammatory response syndrome (SIRS). Thus it is difficult to determine in certain situations, whether empiric antibiotic treatment is warranted. Serum procalcitonin (PCT) is known to be elevated in bacterial infections, but its performances in predicting bacterial infection among patients with AMI, who might benefit from appropriate empiric management, is unknown.

Methods

A prospective observational study was conducted at Assaf Harofeh Medical Center, Israel. Serum PCT was collected within 48 hours from patients presenting with AMI. Demographic, clinical, and laboratory data, were collected prospectively. Two experienced Infectious Diseases (ID) specialists who were blinded to the PCT results, independently determined the gold standard for infection in every patient. By utilizing sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and the area under the ROC curve (AUC), the performance of PCT, fever, white-blood cells (WBC) count and C-reactive protein (CRP) for infection diagnosis was calculated.

Results

The analysis included 230 AMI patients (age 63.0 ± 13.0 years), of which 36 (15.6%) were determined to be infected. The best cutoff for PCT as a differentiating marker between infected and non-infected patients was achieved at 0.09ng/dl (sensitivity 94.4%, specificity 85.1%, AUC ROC 0.94). This test outperformed CRP, WBC, and fever, for infection diagnosis (figure).

Conclusion

PCT should be utilized for ruling out infection in AMI patients by utilizing serum PCT>0.09ng/dl (i.e., ≥0.1ng/dl) as a cutoff.

Disclosures

All authors: No reported disclosures.

Comparative Effectiveness of Vancomycin vs. Metronidazole in Mild Clostridium difficile Infections, and Potential Impact on Subsequent Vancomycin-Resistant Enterococcus (VRE) Isolation

Background

The epidemiology and clinical characteristics of Clostridium difficile infections (CDI) have evolved dramatically in the past decade. Vancomycin is the treatment of choice for moderate to severe CDI, with superior cure rates observed in comparative trials. However, controlled comparative efficacy data pertaining to mild CDI is lacking. Furthermore, the potential impact of vancomycin treatment on subsequent Vancomycin-Resistant Enterococcus (VRE) isolation rates remains unknown at the individual patient level.

Methods

A Retrospective cohort analysis was executed at the Assaf Harofeh Medical Center, Israel, from 2010 to 2015. Adult patients (>18 years) with a first episode of acute CDI, determined per pre-established criteria, were enrolled. The efficacy of vancomycin vs..metronidazole was evaluated in the subset of patients with mild CDI. The outcomes of patients, who received vancomycin or metronidazole (but not both), were compared by Cox regression. A prediction score was used to control for possible confounders associated with being treated with vancomycin. The independent association of oral vancomycin treatment during the acute CDI and later (up to 18 months) VRE isolation was analyzed using Cox regression.

Results

A total of 413 patients with CDI were included in the study. The majority were elderly (median age 75 years, range 19–120), and had extensive comorbidities (mean Charlson’s combined condition score 6.7 ± 3.4) and significant acute illness indices (35% with severe to fulminant Horn index). Among 126 patients with mild disease, no differences were observed in terms of clinical outcomes between vancomycin or metronidazole treatment. Metronidazole remained non-inferior even after incorporating a prediction score to control for confounders associated with being a “vancomycin case”. Ten patients had new post-CDI VRE isolation. In multivariable analysis, oral vancomycin treatment during the acute CDI was the strongest independent predictor for later isolation of VRE (aOR=6.7, P = 0.04).

Conclusion

Our study suggests that metronidazole should remain the recommended treatment of choice for mild CDI, due to clinical non-inferiority and an apparent association between vancomycin therapy and subsequent VRE isolation on an individual patient level analysis.

Disclosures

All authors: No reported disclosures.

Bathing hospitalized dependent patients with prepackaged disposable washcloths instead of traditional bath basins: A case-crossover study

BACKGROUND

Basins used for patient bathing have been shown to be contaminated with multidrug-resistant organisms (MDROs) and have prompted the evaluation of alternatives to soap and water bathing methods.

METHODS

We conducted a prospective, randomized, open-label interventional crossover study to assess the impact of replacing traditional bath basins with prepackaged washcloths on the incidence of hospital-associated infections (HAIs), MDROs, and secondarily, rates of skin deterioration. Unit-wide use of disposable washcloths over an 8-month period was compared with an 8-month period of standard care using basins.

RESULTS

A total of 2,637 patients were included from 2 medical-surgical units at a single tertiary medical center, contributing 16,034 patient days. During the study period, there were a total of 33 unit-acquired infections, the rates of which were not statistically different between study phases (incidence rate ratio, 1.05; 95% confidence interval [CI], 0.50-2.23; P = .88). However, occurrence of skin integrity deterioration was significantly less in the intervention group (odds ratio, 0.44; 95% CI, 0.22-0.88; P = .02).

CONCLUSIONS

Although we were unable to demonstrate a significant reduction in HAI or MDRO acquisition, we found a decrease in skin deterioration with the use of disposable washcloths and confirmed earlier findings of MDRO contamination of wash basins.

The Continuing Plague of Extended-spectrum β-lactamase-producing Enterobacteriaceae Infections

Antimicrobial resistance is a common iatrogenic complication of modern life and medical care. One of the most demonstrative examples is the exponential increase in the incidence of extended-spectrum β-lactamases (ESBLs) production among Enterobacteriaceae, which is the most common human pathogens outside of the hospital settings. Infections resulting from ESBL-producing bacteria are associated with devastating outcomes, now affecting even previously healthy individuals. This development poses an enormous burden and threat to public health. This paper aims to narrate the evolving epidemiology of ESBL infections, and highlight current challenges in terms of management and prevention of these common infections.

Clinical and molecular epidemiology of Acinetobacter baumannii bloodstream infections in an endemic setting

AIM

The transmission dynamics of Acinetobacter baumannii in endemic settings, and the relation between microbial properties and patients' clinical outcomes, are yet obscure and hampered by insufficient metadata.

METHODS & RESULTS

Of 20 consecutive patients with A. baumannii bloodstream infection that were thoroughly analyzed at a single center, at least one transmission opportunity was evident for 85% of patients. This implies that patient-to-patient transmission is the major mode of A. baumannii acquisitions in health facilities. Moreover, all patients who died immediately (<24 h of admission) were infected with a single clone (ST457; relative risk = 1.6; p = 0.05).

CONCLUSION

This preliminary analysis should prompt further investigation by mapping genomic virulence determinants among A. baumannii ST457 lineage compared with other strains.

A Comparison of Molecular Typing Methods Applied to Enterobacter cloacae complex: hsp60 Sequencing, Rep-PCR, and MLST

Molecular typing using repetitive sequenced-based PCR (rep-PCR) and hsp60 sequencing were applied to a collection of diverse Enterobacter cloacae complex isolates. To determine the most practical method for reference laboratories, we analyzed 71 E. cloacae complex isolates from sporadic and outbreak occurrences originating from 4 geographic areas. While rep-PCR was more discriminating, hsp60 sequencing provided a broader and a more objective geographical tracking method similar to multilocus sequence typing (MLST). In addition, we suggest that MLST may have higher discriminative power compared to hsp60 sequencing, although rep-PCR remains the most discriminative method for local outbreak investigations. In addition, rep-PCR can be an effective and inexpensive method for local outbreak investigation.

A Comparison of Molecular Typing Methods Applied to Enterobacter cloacae complex: hsp60 Sequencing, Rep-PCR, and MLST

Molecular typing using repetitive sequenced-based PCR (rep-PCR) and hsp60 sequencing were applied to a collection of diverse Enterobacter cloacae complex isolates. To determine the most practical method for reference laboratories, we analyzed 71 E. cloacae complex isolates from sporadic and outbreak occurrences originating from 4 geographic areas. While rep-PCR was more discriminating, hsp60 sequencing provided a broader and a more objective geographical tracking method similar to multilocus sequence typing (MLST). In addition, we suggest that MLST may have higher discriminative power compared to hsp60 sequencing, although rep-PCR remains the most discriminative method for local outbreak investigations. In addition, rep-PCR can be an effective and inexpensive method for local outbreak investigation.

Antibiotic Resistance of Non-pneumococcal Streptococci and Its Clinical Impact

The taxonomy of streptococci has undergone major changes during the last two decades. The present classification is based on both phenotypic and genotypic data. Phylogenetic classification of streptococci is based on 16S rRNA sequences [1], and it forms the backbone of the overall classification system of streptococci. Phenotypic properties are also important, especially for clinical microbiologists. The type of hemolysis on blood agar, reaction with Lancefield grouping antisera, resistance to optochin, and bile solubility remain important for grouping of clinical Streptococcus isolates and therefore treatment options [2]. In the following chapter, two phenotypic classification groups, viridans group streptococci (VGS) and beta-hemolytic streptococci, will be discussed.

Intra-abdominal Infections: The Role of Anaerobes, Enterococci, Fungi, and Multidrug-Resistant Organisms

Background.

Intra-abdominal infections (IAI) constitute a common reason for hospitalization. However, there is lack of standardization in empiric management of (1) anaerobes, (2) enterococci, (3) fungi, and (4) multidrug-resistant organisms (MDRO). The recommendation is to institute empiric coverage for some of these organisms in “high-risk community-acquired” or in “healthcare-associated” infections (HCAI), but exact definitions are not provided.

Methods.

Epidemiological study of IAI was conducted at Assaf Harofeh Medical Center (May–November 2013). Logistic and Cox regressions were used to analyze predictors and outcomes of IAI, respectively. The performances of established HCAI definitions to predict MDRO-IAI upon admission were calculated by receiver operating characteristic (ROC) curve analyses.

Results.

After reviewing 8219 discharge notes, 253 consecutive patients were enrolled (43 [17%] children). There were 116 patients with appendicitis, 93 biliary infections, and 17 with diverticulitis. Cultures were obtained from 88 patients (35%), and 44 of them (50%) yielded a microbiologically confirmed IAI: 9% fungal, 11% enterococcal, 25% anaerobic, and 34% MDRO. Eighty percent of MDRO-IAIs were present upon admission, but the area under the ROC curve of predicting MDRO-IAI upon admission by the commonly used HCAI definitions were low (0.73 and 0.69). Independent predictors for MDRO-IAI were advanced age and active malignancy.

Conclusions.

Multidrug-resistant organism-IAIs are common, and empiric broad-spectrum coverage is important among elderly patients with active malignancy, even if the infection onset was outside the hospital setting, regardless of current HCAI definitions. Outcomes analyses suggest that empiric regimens should routinely contain antianaerobes (except for biliary IAI); however, empiric antienterococcal or antifungals regimens are seldom needed.

Screening for carbapenem-resistant Enterobacteriaceae: Who, When, and How?

The global spread of carbapenem-resistant Enterobacteriaceae (CRE) has been fostered by the lack of preemptive screening of patients in healthcare facilities that could prevent patient-to-patient transmission. Outbreaks of CRE infections have led some institutions to implement rigorous screening programs, although controlled comparative data are frequently lacking. Resource limitations and uncertainty regarding the optimal approach has kept many facilities from enacting more active routine surveillance policies that could reduce the prevalence of CRE. The ideal population to target for screening, the frequency of testing, and the preferred test method are components of surveillance programs that remain open to debate. This review discusses the rationale for different screening policies in use and the performance characteristics of laboratory methods available to detect CRE carriage.

Predictors of Clostridium difficile infection-related mortality among older adults

BACKGROUND

Over 90% of annual deaths caused by Clostridium difficile infection (CDI) occur in persons aged ≥65 years. However, no large-scale studies have been conducted to investigate predictors of CDI-related mortality among older adults.

METHODS

This case-control study included 540 CDI patients aged ≥60 years admitted to a tertiary care hospital in Detroit, Michigan, between January 2005 and December 2012. Cases were CDI patients who died within 30 days of CDI date. Controls were CDI patients who survived >30 days after CDI date. Cases were matched to controls on a 1:3 ratio based on age and hospital acquisition of CDI.

RESULTS

One-hundred and thirty cases (25%) were compared with 405 controls (75%). Independent predictors of CDI-related mortality included admission from another acute hospital (odds ratio [OR], 8.25; P = .001) or a long-term care facility (OR, 13.12; P = .012), McCabe score ≥2 (OR, 12.19; P < .001), and high serum creatinine (≥1.7 mg/dL) (OR, 3.43; P = .021). The regression model was adjusted for the confounding effect of limited activity of daily living score, total number of antibiotic days prior to CDI, ileus on abdominal radiograph, low albumin (≤2.5 g/dL), elevated white blood cell count (>15 × 1,000/mm³), and admission to intensive care unit because of CDI.

CONCLUSIONS

Predictors of CDI-related mortality reported in this study could be applied to the development of a bedside scoring system for older adults with CDI.

Multidrug-Resistant Gram-Negative Bacilli: Infection Control Implications

Antimicrobial resistance is a common iatrogenic complication of both modern life and medical care. Certain multidrug resistant and extensively drug resistant Gram-negative organisms pose the biggest challenges to health care today, predominantly owing to a lack of therapeutic options. Containing the spread of these organisms is challenging, and in reality, the application of multiple control measures during an evolving outbreak makes it difficult to measure the relative impact of each measure. This article reviews the usefulness of various infection control measures in containing the spread of multidrug-resistant Gram-negative bacilli.

Ten years with colistin: a retrospective case series

OBJECTIVE

At the Shaare Zedek Medical Center, we have been using colistimethate sodium (CMS) for empiric as well as pathogen-directed treatment. We present our 10-year experience.

METHODS

We conducted a retrospective case-series analysis of patients admitted from 1 January 2004 through 1 May 2014 who received at least one dose of CMS. Patient characteristics analysed for all admission for which patients received CMS, included: age, number of re-admissions, admission ward, renal function, disposition and microbiology results. Overall trend in defined daily dose (DDD) for CMS and resistant isolates was analysed.

RESULTS

A total of 5603 admissions met inclusion criteria. Patients' mean (±SD) age was 80 ± 14 years, 1162 (48%) of the admissions were from a healthcare facility and 4367 (78%) of the admissions were to general Internal Medicine wards. The median number of hospital admissions per patient was 5, median admission and discharge creatinine (mg/dl) were 1.05 and 1.01, respectively; 2.3% of admissions required first-time dialysis. The discharge rate from the hospital was 58.4%. Excluding intrinsically CMS-resistant gram-negative organisms, bloodstream and urine isolates were 98% and 100% susceptible, respectively. CMS use (DDDs) increased during the study (p for trend = 0.04) without significant increase in incidence of multidrug-resistant organisms.

CONCLUSIONS

Colistimethate sodium use at our institution has increased during this 10-year period. Nevertheless, there is no increasing trend in CMS-resistant organisms, 58% of the patients were discharged alive, and we did not observe significant nephrotoxicity in patients prescribed CMS. CMS should be reserved for microbiologically confirmed extensively drug-resistant gram-negative infections.

Contact Precautions More Is Not Necessarily Better

Objective.

To determine whether increases in contact isolation precautions are associated with decreased adherence to isolation practices among healthcare workers (HCWs).

Design.

Prospective cohort study from February 2009 to October 2009.

Setting.

Eleven teaching hospitals.

Participants.

HCWs.

Methods.

One thousand thirteen observations conducted on HCWs. Additional data included the number of persons in isolation, types of HCWs, and hospital-specific contact precaution practices. Main outcome measures included compliance with individual components of contact isolation precautions (hand hygiene before and after patient encounter, donning of gown and glove upon entering a patient room, and doffing upon exiting) and overall compliance (all 5 measures together) during varying burdens of isolation.

Results.

Compliance with hand hygiene was as follows: prior to donning gowns/gloves, 37.2%; gowning, 74.3%; gloving, 80.1%; doffing of gowns/gloves, 80.1%; after gown/glove removal, 61%. Compliance with all components was 28.9%. As the burden of isolation increased (20% or less to greater than 60%), a decrease in compliance with hand hygiene (43.6%—4.9%) and with all 5 components (31.5%—6.5%) was observed. In multivariable analysis, there was an increase in noncompliance with all 5 components of the contact isolation precautions bundle (odds ratio [OR], 6.6 [95% confidence interval (CI), 1.15-37.44];P= .03) and in noncompliance with hand hygiene prior to donning gowns and gloves (OR, 10.1 [95% CI, 1.84—55.54];P= .008) associated with increasing burden of isolation.

Conclusions.

As the proportion of patients in contact isolation increases, compliance with contact isolation precautions decreases. Placing 40% of patients under contact precautions represents a tipping point for noncompliance with contact isolation precautions measures.

Risk factors and acute in-hospital costs for infected pressure ulcers among gunshot-spinal cord injury victims in southeastern Michigan

BACKGROUND

Management of pressure ulcers (PrUs) in patients with gunshot-spinal cord injuries (SCIs) presents unique medical and economic challenges for practitioners.

METHODS

A retrospective chart review was conducted at 3 acute care hospitals in metropolitan Detroit for patients admitted with PrUs due to gunshot-SCIs between January 2004 and December 2008. Multivariate analysis using logistic regression was conducted to choose for the independent predictors of infected PrUs. Mean adjusted in-hospital costs per patient and per hospitalization were calculated and compared between infected and noninfected PrUs.

RESULTS

The study cohort included 201 gunshot-SCI patients with PrUs contributing to 395 admissions, including readmissions, between 2004 and 2008. Seventy-six patients (38%) had infected PrUs at time of the index admission. Independent predictors of infected PrUs on index admission included Charlson Comorbidity Index ≥2 (odds ratio, 2.18, P = .026) and stage III/IV PrU (odds ratio, 4.82; P <.0001). During the study period, the cumulative median duration of hospitalization per patient was 12 days (interquartile range, 6-24 days), resulting in a mean adjusted cost of $19,969 ± $6639 per patient. The mean adjusted cost per hospitalization for patients with infected PrUs was significantly higher than that for patients with noninfected PrUs ($16,735 ± $8310 vs $12,356 ± $7007; P <.001).

CONCLUSIONS

A multidisciplinary approach including home-based rehabilitation programs and SCI wound clinics might help prevent PrUs and their complications and reduce associated costs.

Risk Factors and Outcomes for Carbapenem-Resistant Klebsiella pneumoniae Isolation, Stratified by Its Multilocus Sequence Typing: ST258 Versus Non-ST258

A “high risk” clone of carbapenem-resistant Klebsiella pneumoniae (CRKP) identified by multilocus sequence typing (MLST) as sequence type (ST) 258 has disseminated worldwide. As the molecular epidemiology of the CRE pandemic continues to evolve, the clinical impact of non-ST258 strains is less well defined. We conducted an epidemiological investigation of CRKP based on strains MLST. Among 68 CRKP patients, 61 were ST258 and 7 belonged to non-ST258. Klebsiella pneumoniae ST258 strains were significantly associated with bla_KPC production and with resistance to an increased number of antimicrobials. Clinical outcomes were not different. Based on this analysis, one cannot rely solely on the presence of bla_KPC in order to diagnose CRKP.

Diabetic foot infection in hospitalized adults

BACKGROUND

Acute infections of the diabetic foot (DFI) are a common and complex condition. Patients are generally managed in the ambulatory setting and epidemiological data pertaining to hospitalized patients is lacking. The aim of this study was to analyze the epidemiology, microbiology and outcomes of hospitalized patients with DFI, who are managed at a referral center equipped with hyperbaric oxygen (HBO) therapy.

METHODS

A retrospective cohort study of adult patients admitted to a tertiary referral center with DFI over a six-month period in 2013 was undertaken. Predictors of clinical outcomes and efficacy of treatment modalities were analyzed by Cox regression.

RESULTS

Sixty-one patients with DFI were identified. Most patients were elderly (67 ± 13 years), with long-standing (17 ± 9 years), poorly controlled (HbA1c 9 ± 3%) diabetes. Most patients had polymicrobial infection (80%); specifically, anaerobic (39%) and multi or extensively-drug resistant organisms (61%). Administration of appropriate antimicrobials was delayed for >48 h in 83%. Advanced age was associated with worse outcomes. Sicker patients with severe peripheral vascular disease were managed with HBO. The use of HBO was associated with higher costs and increased functional deterioration, and did not prevent future limb amputation.

CONCLUSIONS

Our study illustrates the descriptive epidemiology of hospitalized adults with DFI predominantly of polymicrobial etiology. MDROs and anaerobic organisms are common causative pathogens, and appropriate antibiotics were frequently delayed. HBO treatment may delay the need for limb amputation, but not obviate this eventual outcome.

Epidemiology of CTX-M-type extended-spectrum β-lactamase-producing Escherichia coli among older adults

To identify independent predictors for isolation of CTX-M-type extended-spectrum β-lactamase-producing Escherichia coli (CTX-M E coli) in older adults (>65 years old), 87 cases with CTX-M E coli isolation were compared with matched controls without E coli isolation. Institutionalized residence, multiple comorbidities, and urinary catheter were independent predictors of CTX-M E coli among older adults.

Risk factors for bloodstream infection caused by extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae: A focus on antimicrobials including cefepime

BACKGROUND

Extended-spectrum β-lactamase (ESBL)-producing pathogens represent increasing challenges to physicians because of rising prevalence, high mortality, and challenging treatment. Identifying high risks and early appropriate therapy is critical to favorable outcomes.

METHODS

This is a 5-year retrospective case-case-control study performed at the Detroit Medical Center on adult patients with bloodstream infection (BSI) caused by ESBL-producing and non-ESBL-producing Escherichia coli or Klebsiella pneumoniae, each compared with uninfected controls. Data were collected from December 2004-August 2009. Multivariate analysis was performed using logistic regression.

RESULTS

Participants included 103 patients with BSI caused by ESBL-producing pathogens and 79 patients with BSI caused by pathogens that did not produce ESBLs. The mean age of patients in the ESBL group was 67 years; of the patients, 51% were men, 77% were black, and 38% (n = 39) died in hospital. The mean age of patients in the non-ESBL group was 58 years; of the patients, 51% were men, 92% were black, and 22% (n = 17) died in hospital. On multivariate analysis, predictors of BSI caused by ESBL-producing pathogens included central venous catheter (odds ratio [OR], 29.4; 95% confidence interval [CI], 3.0-288.3), prior β-lactam-/β-lactamase-inhibitor therapy (OR, 28.1; 95% CI, 1.99-396.5), and prior cefepime therapy (OR, 22.7; 95% CI, 2.7-192.4). The only risk factor for BSI caused by non-ESBL-producing pathogens was urinary catheter insertion (OR, 18.2; 95% CI, 3.3-100.3).

CONCLUSION

Prior antimicrobial therapy, particularly with β-lactam, was the strongest unique risk factor for BSI caused by ESBL-producing E coli or K pneumoniae.

Simple bedside score to optimize the time and the decision to initiate appropriate therapy for carbapenem-resistant Enterobacteriaceae

BACKGROUND

Epidemiological characteristics of patients with bloodstream infections (BSI) due to extended-spectrum β-lactamase producing (ESBL) and carbapenem-resistant (CRE) strains are often similar. Mortality rates for CRE BSI are 70%, and mean time to initiation of appropriate therapy is ~5 days. A bedside score was developed to differentiate CRE-BSIs from ESBL-BSIs, in order to help decrease the time to initiation of appropriate therapy for CRE and mortality rates.

FINDINGS

Score was developed based of data (2007-2010) abstracted from charts of adult patients from Assaf Harofeh Medical Center (AHMC, Zeriffin, Israel), and validated on a cohort of patients from Detroit Medical Center (DMC, MI, USA). A multivariate model for presence of CRE was generated. A clinical prediction score and ROC curve was derived. 451 patients with ESBL BSIs (285 from AHMC and 166 from DMC) and 74 patients with CRE BSIs (58 from AHMC and 16 from DMC) were included. The prediction score included chemotherapy in the past 3 months (19 points), presence of foreign invasive devices (10 points), no peripheral vascular disease (10 points), reduced consciousness or cognition at time of acute illness (9 points), time in hospital prior to BSI ≥ 3 days (7 points), and age younger than 65 years (6 points). A score of ≥32 to define "high CRE risk" had sensitivity of 59%, specificity of 76%, PPV of 34% and NPV of 90%.

CONCLUSIONS

The score's 90% NPV implies it could reduce un-necessary (and toxic) empiric use of anti-CRE therapeutics, but this should be studied prospectively and on broader populations in order to test its potential role in reducing mortality.

The complex epidemiology of extended-spectrum β-lactamase-producing Enterobacteriaceae

ABSTRACT 

Antimicrobial resistance is a growing worldwide iatrogenic complication of modern medical care. Extended-spectrum β-lactamases have emerged as one of the most successful resistance mechanisms, limiting our therapeutic options to treat various human infections. The dissemination of these enzymes to the community probably signifies an irreversible step. This paper will review the evolution of human infections associated with extended-spectrum β-lactamase-producing organisms in the past 20 years, and will present and discuss the current challenges, controversies, debates and knowledge gaps in this research field.