Bacillus licheniformis is a Gram-positive bacterium commonly found in soil and water. There have been very few reports on the pathogenicity of B. licheniformis in humans. In this prospective study, the emergence of cases affected by B. licheniformis during a period of 38 days was reported together with investigations into the sources of spread to hospitalized patients in a tertiary hospital.

Blood cultures of 45 patients grew Bacillus spp. in October and November, 2021. To identify the source and prevent further dissemination of the pathogen, all commonly used materials were examined. Samples obtained from alcohol/water solutions yielded positive results for Bacillus spp., which pointed to the main distilled water tank of the hospital, subsequently found to be the main source. All isolates were sent for molecular analysis by arbitrarily-primed polymerase chain reaction (AP-PCR).

Molecular analysis with AP-PCR of 29 positive cultures showed a closely related clone of B. licheniformis in 25 specimens, including 23 blood samples and two distilled water samples. Considering the rarity of true infections with B. licheniformis and the mild clinical picture of the affected patients, the dissemination was considered to be a pseudo-outbreak.

Prompt detection and elimination of any pathogenic spread and differentiation of a pseudo-outbreak from a true outbreak are of utmost importance in preventing unnecessary antibiotic prescriptions, diagnostic procedures, and interventions.

To evaluate potential modifications to the Centers for Disease Control and Prevention (CDC)’s Adult Sepsis Event (ASE) definition aimed at mitigating variable blood culturing practices, better-capturing cases where timely care may have prevented deterioration, and improving clinical credibility.

Retrospective observational study

5 US hospitals

Hospitalized adults, 2015–2022

We assessed the impact of potential ASE modifications on community-onset sepsis incidence and mortality and reviewed 280 charts to assess positive predictive value (PPV) for clinical sepsis.

Among 1,101,252 hospitalized adults, 51,712 (4.7%) met community-onset ASE criteria (16.1% mortality). Expanding infection criteria to include present-on-admission infection codes when blood cultures were not drawn, non-blood clinical cultures, and discharge alive on antibiotic day three increased incidence by 15.0%, 12.2%, and 4.9%, respectively; all led to mild decreases in mortality rates. Expanding organ dysfunction criteria to include hypotension increased ASE incidence by 32.3% and decreased mortality by 18.5%. Broadening respiratory failure criteria to include noninvasive ventilation and high-flow oxygen had minimal impact. On chart review, original ASE criteria had 80% PPV for clinical sepsis. PPV was similar when identifying infection using present-on-admission infection codes instead of blood cultures and when including patients discharged alive on antibiotic day three. PPV decreased to 50% when using non-blood clinical cultures to identify infection, 17% when using single hypotension values alone to indicate organ dysfunction, and 30% when all ASE components occurred exactly 2 days vs within +/-1 day from the blood culture day.

Our findings inform modifications to ASE to optimize its utility for national epidemiologic monitoring and quality measurement.

During the COVID-19 pandemic, the United States Centers for Disease Control and Prevention provided strategies, such as extended use and reuse, to preserve N95 filtering facepiece respirators (FFR). We aimed to assess the prevalence of N95 FFR contamination with SARS-CoV-2 among healthcare personnel (HCP) in the Emergency Department (ED).

Real-world, prospective, multicenter cohort study. N95 FFR contamination (primary outcome) was measured by real-time quantitative polymerase chain reaction. Multiple logistic regression was used to assess factors associated with contamination.

Six academic medical centers.

ED HCP who practiced N95 FFR reuse and extended use during the COVID-19 pandemic between April 2021 and July 2022.

Total number of COVID-19-positive patients treated.

Two-hundred forty-five N95 FFRs were tested. Forty-four N95 FFRs (18.0%, 95% CI 13.4, 23.3) were contaminated with SARS-CoV-2 RNA. The number of patients seen with COVID-19 was associated with N95 FFR contamination (adjusted odds ratio, 2.3 [95% CI 1.5, 3.6]). Wearing either surgical masks or face shields over FFRs was not associated with FFR contamination, and FFR contamination prevalence was high when using these adjuncts [face shields: 25% (16/64), surgical masks: 22% (23/107)].

Exposure to patients with known COVID-19 was independently associated with N95 FFR contamination. Face shields and overlying surgical masks were not associated with N95 FFR contamination. N95 FFR reuse and extended use should be avoided due to the increased risk of contact exposure from contaminated FFRs.

Sponge-Sticks (SS) and ESwabs are frequently utilized for detection of multidrug-resistant organisms (MDROs) in the environment. Head-to-head comparisons of SS and ESwabs across recovery endpoints are limited.

We compared MDRO culture and non-culture-based recovery from (1) ESwabs, (2) cellulose-containing SS (CS), and (3) polyurethane-containing SS (PCS).

Known quantities of each MDRO were pipetted on a stainless-steel surface and swabbed by each method. Samples were processed, cultured, and underwent colony counting. DNA was extracted from sample eluates, quantified, and underwent metagenomic next-generation sequencing (mNGS). MDROs underwent whole genome sequencing (WGS). MDRO recovery from paired patient perirectal and PCS-collected environmental samples from clinical studies was determined.

Laboratory experiment, tertiary medical center, and long-term acute care facility.

Culture-based recovery varied across MDRO taxa, it was highest for vancomycin-resistant Enterococcus and lowest for carbapenem-resistant Pseudomonas aeruginosa (CRPA). Culture-based recovery was significantly higher for SS compared to ESwabs except for CRPA, where all methods performed poorly. Nucleic acid recovery varied across methods and MDRO taxa. Integrated WGS and mNGS analysis resulted in successful detection of antimicrobial resistance genes, construction of high-quality metagenome-assembled genomes, and detection of MDRO genomes in environmental metagenomes across methods. In paired patient and environmental samples, multidrug-resistant Pseudomonas aeruginosa (MDRP) environmental recovery was notably poor (0/123), despite detection of MDRP in patient samples (20/123).

Our findings support the use of SS for the recovery of MDROs. Pitfalls of each method should be noted. Method selection should be driven by MDRO target and desired endpoint.

To assess whether universal masking during the COVID-19 pandemic reduced neonatal acquisition of S. aureus.

We performed a retrospective cohort study of neonates admitted to a level three regional NICU for three years before and after implementation of universal masking for the COVID-19 pandemic. Multivariable proportional hazards regression models evaluated the effect of masking on time-to-acquisition of methicillin-resistant and methicillin-sensitive S. aureus (MRSA and MSSA) while adjusting for fixed and time-varying neonatal characteristics.

We analyzed 2,728 neonates, 1,446 pre-pandemic and 1,282 post-pandemic; 84.9% were inborn, with mean gestational age of 34 weeks and 6 days (SD = 4.2) and mean birthweight of 2,500 grams (SD = 975). The mean number of screening cultures per neonate was 3.07 (SD = 3.31). When adjusting for covariates, universal masking was associated with decreased acquisition of MRSA (hazard ratio =0.43 (95% CI: 0.19–0.99), p = 0.04) but not MSSA (HR = 1.27 (95% CI: 00.87–1.85), p = 0.21). Among covariates, airway devices and maternal S. aureus status were associated with S. aureus acquisition.

Universal masking decreased the rate of NICU MRSA acquisition by 60% while MSSA acquisition was unchanged. Masking may reduce MRSA spread via colonized healthcare personnel while MSSA may be more likely to be acquired from parental skin-to-skin contact and was thus unaffected by masking.

To understand the scenarios where health care worker (HCW) masking is most impactful for preventing nosocomial transmission.

A mathematical agent-based model of nosocomial spread with masking interventions. Masking adherence, community prevalence, disease transmissibility, masking effectiveness, and proportion of breakroom (unmasked) interactions were varied. The main outcome measure is the total number of nosocomial infections in patients and HCW populations over a simulated three-month period.

HCW masking around patients and universal HCW masking reduces median patient nosocomial infections by 15% and 18%, respectively. HCW-HCW interactions are the dominant source of HCW infections and universal HCW masking reduces HCW nosocomial infections by 55%. Increasing adherence shows a roughly linear reduction in infections. Even in scenarios where a high proportion of interactions are unmasked “breakroom” interactions, masking is still an effective tool assuming adherence is high outside of these areas. The optimal scenarios where masking is most impactful are those where community prevalence is at a medium level (around 2%) and transmissibility is high.

Masking by HCWs is an effective way to reduce nosocomial transmission at all levels of mask effectiveness and adherence. Increases in adherence to a masking policy can provide a small but important impact. Universal HCW masking policies are most impactful should policymakers wish to target HCW infections. The more transmissible a variant in circulation is, the more impactful HCW masking is for reducing infections. Policymakers should consider implementing masking at the point when community prevalence is optimum for maximum impact.

To describe the mitigation strategies for a Candida auris outbreak in a cardiothoracic transplant intensive care unit (CTICU) and its implications for infection prevention practices.

Retrospective cohort study from July 2023 to February 2024.

A large academic medical center.

A multidisciplinary team convened to conduct the outbreak investigation and develop mitigation strategies in the CTICU.

From July 2023 to February 2024, 34 possible hospital-onset cases of C. auris were identified in our CTICU. Whole-genome sequencing and phylogenetic analysis based on pairwise single nucleotide polymorphism (WG-SNP) distance revealed two distinct outbreak clusters. Of the 34 patients, 11 (32.3%) were solid organ transplant recipients and 12 (35.3%) had a mechanical circulatory support device. Of the cohort, only 11/34 (32.3%) had prior exposure to high-risk healthcare facilities within six months prior to admission, as follows: acute inpatient rehabilitation facilities (AIRs) (n = 5, 14.7%), skilled nursing facilities (SNFs) (n = 3, 8.8%), and long-term acute care hospitals (LTACHs) (n = 3, 8.8%). The cohort had a median of 22.0 antibiotic-days prior to their positive results. Five (14.7%) patients had C. auris candidemia, three of whom expired likely due to infection. Infection Prevention (IP) interventions addressed several modes of transmission, including healthcare personnel hands, shared patient equipment, and the environment.

Our experience suggests that the epidemiology of C. auris may be changing, pointing towards a rising prevalence in acute care settings. IP interventions targeting hand hygiene behavior and promoting centralizing cleaning and disinfection of shared patient equipment may have contributed to outbreak resolution.

The antibiotic spectrum index (ASI) outcome quantifies antibiotic exposure based on spectrum of activity. Our objective was to examine ASI as an exploratory outcome in the context of a recent stewardship-focused, clinical trial in childhood pneumonia that originally used a binary guideline-concordant outcome.

Secondary analysis of a randomized clinical trial.

Two tertiary pediatric hospitals.

Encounters were randomly assigned to clinical decision support (CDS) or usual care treatment arm. The ASI was calculated by summing daily ASI scores for each unique antibiotic administered. It was evaluated as a continuous and ordinal measure: No Antibiotics (ASI = 0), Narrow (1-2), Intermediate (3-4), Broad (5-7), and Very Broad (≥8). Proportional odds regression modeled the ordinal ASI outcome in the first 24 hours by treatment arm and compared to the guideline-concordance outcome. Results were stratified by emergency department (ED) disposition. We also conducted a longitudinal, descriptive analysis of day-to-day ASI for those with in-hospital dispositions.

We included 1027 encounters, 549 (53%) were randomized to CDS and 478 (47%) usual care respectively. ASI Category did not differ by treatment arm overall (Odds Ratio: 0.88[95% Confidence Interval: 0.70,1.09]), which mirrored binary guideline-concordance. Mean ASI was lower for concordant encounters (2.1 vs 8.4, P < 0.001) and across all ED dispositions. In the longitudinal analysis, there were 1137 day-to-day ASI comparisons, with only 7% representing spectrum escalations.

The ASI outcome yielded similar results to a dichotomous concordance outcome. However, ASI provided more granular insights into antibiotic prescribing, suggesting ASI may be a useful outcome measure in future stewardship-focused trials.

Interfacility patient transfers contribute to the regional spread of multidrug-resistant organisms (MDROs). We evaluated whether transfer patterns of inpatients with similar characteristics to carbapenem-resistant Enterobacterales (CRE) case-patients (CRE surrogates) better reflect hospital-level CRE burden than traditionally used populations.

We determined the risk factors for subsequent hospital admission using demographic and clinical information from Tennessee Department of Health tracked CRE case-patients from July 2015 to September 2019. Risk factors were used to identify CRE surrogates among inpatients in the 2018 Tennessee Hospital Discharge Data System (HDDS). Transfer networks of CRE surrogates, Medicare/TennCare beneficiaries, and all-inpatients with ≤365 days of intervening community stays were compared with the transfer networks of CRE case-patients in 2019. The associations between hospital-level CRE prevalence and hospitals’ incoming transfer volumes from each network were assessed using negative binomial regression models.

Eight risk factors for subsequent hospital admission were identified from 2,518 CRE case-patients, which were used to match CRE case-patients with HDDS inpatients, resulting in 10,069 surrogate patients. CRE surrogate network showed more structural similarities with the CRE case-patient network than with the all-inpatient and Medicare/TennCare networks. A 33% increase in hospitals’ CRE prevalence in 2019 was associated with each doubling of incoming transfer of CRE surrogates in 2018 (adjusted Risk Ratio [aRR] 1.33, 95%CI: 1.1, 1.59), higher than all-inpatient (aRR 1.27, 95% CI: 1.08, 1.51) and Medicare/TennCare networks (aRR 1.21, 95% CI: 1.02, 1.44).

Surrogate transfer patterns were associated with hospital-level CRE prevalence, highlighting their value in MDRO containment and prevention.

Vancomycin-resistant enterococci (VRE) can cause serious healthcare-associated infections. Patients can become colonized and infected through contact with healthcare workers, hospital surfaces, equipment, and other patients. We evaluated the utility of broadly applied whole-genome sequencing (WGS) surveillance of vancomycin-resistant Enterococcus faecium (VREfm) for detection of hospital-based transmission.

Retrospective genomic and epidemiologic analysis of clinical VREfm isolates

Brigham and Women’s Hospital, an 800-bed tertiary care center in Boston, MA, USA

VREfm was isolated from patient screening and diagnostic specimens. We sequenced the genomes of 156 VREfm isolates, 12 at the request of infection control and 144 as a convenience sample, and used single nucleotide polymorphism (SNP) differences to assess relatedness. For isolate pairs separated by 15 or fewer SNPs by two orthogonal comparison methods, we mapped epidemiologic connections to identify putative transmission clusters.

We found evidence for 16 putative transmission clusters comprising between two and four isolates each and involving 41/156 isolates (26.3%). Our analysis discovered 14 clusters that were missed by traditional surveillance methods and additional members of two clusters that were detected by traditional methods. Patients in four transmission clusters were linked only by exposure to the postanesthesia care unit.

We show that WGS surveillance for VREfm can support infection control investigations and detect transmission events missed by routine surveillance methods. We identify the postanesthesia care unit as a locus for VREfm transmission, which demonstrates how WGS surveillance could inform targeted interventions to prevent the spread of VREfm.